Diatoms are single-celled microalgae with silica-based cell walls (frustules) that are abundantly present in aquatic habitats, and form the basis of the food chain in many ecosystems. Many benthic diatoms have the remarkable ability to glide on all natural or man-made underwater surfaces using a carbohydrate- and protein-based adhesive to generate traction. Previously, three glycoproteins, termed FACs (Frustule Associated Components), have been identified from the common fouling diatom Craspedostauros australis and were implicated in surface adhesion through inhibition studies with a glycan-specific antibody. The polypeptide sequences of FACs remained unknown, and it was unresolved whether the FAC glycoproteins are indeed involved in adhesion, or whether this is achieved by different components sharing the same glycan epitope with FACs. Here we have determined the polypeptide sequences of FACs using peptide mapping by LC–MS/MS. Unexpectedly, FACs share the same polypeptide backbone (termed CaFAP1), which has a domain structure of alternating Cys-rich and Pro-Thr/Ser-rich regions reminiscent of the gel-forming mucins. By developing a genetic transformation system for C. australis, we were able to directly investigate the function of CaFAP1-based glycoproteins in vivo. GFP-tagging of CaFAP1 revealed that it constitutes a coat around all parts of the frustule and is not an integral component of the adhesive. CaFAP1-GFP producing transformants exhibited the same properties as wild type cells regarding surface adhesion and motility speed. Our results demonstrate that FAC glycoproteins are not involved in adhesion and motility, but might rather act as a lubricant to prevent fouling of the diatom surface.

During mitosis, adherent animal cells undergo a drastic shape change, from essentially flat to round, in a process known as mitotic cell rounding (MCR). The aim of this thesis was to critically examine the physical and biological basis of MCR. The experimental part of this thesis employed a combined optical microscope-atomic force microscope (AFM) setup in conjunction with flat tipless cantilevers to analyze cell mechanics, shape and volume. To this end, two AFM assays were developed: the constant force assay (CFA), which applies constant force to cells and measures the resultant height, and the constant height assay (CHA), which confines cell height and measures the resultant force. These assays were deployed to analyze the shape and mechanical properties of single cells trans-mitosis. The CFA results showed that cells progressing through mitosis could increase their height against forces as high as 50 nN, and that higher forces can delay mitosis in HeLa cells. The CHA results showed that mitotic cells confined to ~50% of their normal height can generate forces around 50-100 nN without disturbing mitotic progression. Such forces represent intracellular pressures of at least 200 Pascals and cell surface tensions of around 10 nN/µm. Using the CHA to compare mitotic cell rounding with induced cell rounding, it was observed that the intracellular pressure of mitotic cells is at least 3-fold higher than rounded interphase cells. To investigate the molecular basis of the mechanical changes inherent in mitotic cell rounding, inhibitors and toxins were used to pharmacologically dissect the role of candidate cellular processes. These results implicated the actomyosin cortex and osmolyte transporters, the most prominent of which is the Na+/H+ exchanger, in the maintenance of mechanical properties and intracellular hydrostatic pressure. Observations on blebbing cells under the cantilever supported the idea that the actomyosin cortex is required to sustain hydrostatic pressure and direct this pressure into cell shape changes. To gain further insight into the relationship between actomyosin activity and intracellular pressure, dynamic perturbation experiments were conducted. To this end, the CHA was used to evaluate the pressure and volume of mitotic cells before, during and after dynamic perturbations that included tonic shocks, influx of specific inhibitors, and exposure to pore-forming toxins. When osmotic pressure gradients were depleted, pressure and volume decreased. When the actomyosin cytoskeleton was abolished, cell volume increased while rounding pressure decreased. Conversely, stimulation of actomyosin cortex contraction triggered an increase in rounding pressure and a decrease in volume. Taken together, the dynamic perturbation results demonstrated that the actomyosin cortex contracts against an opposing intracellular pressure and that this relationship sets the surface tension, pressure and volume of the cell. The discussion section of this thesis provides a comprehensive overview of the physical basis of MCR by amalgamating the experimental results of this thesis with the literature. Additionally, the biochemal signaling pathways and proteins that drive MCR are collated and discussed. An exhaustive and unprecedented synthesis of the literature on cell rounding (approx. 750 papers as pubmed search hits on “cell rounding”, April 2012) reveals that the spread-to-round transition can be thought of in terms of a surface tension versus adhesion paradigm, and that cell rounding can be physically classified into four main modes, of which one is an MCR-like category characterized by increased actomyosin cortex tension and diminution of focal adhesions. The biochemical pathways and signaling patterns that correspond with these four rounding modes are catalogued and expounded upon in the context of the relevant physiology. This analysis reveals cell rounding as a pertinent topic that can be leveraged to yield insight into core principles of cell biophysics and tissue organization. It furthermore highlights MCR as a model problem to understand the adhesion versus cell surface tension paradigm in cells and its fundamentality to cell shape, mechanics and physiology.

Ma thèse a porté sur des complexes de polyélectrolytes en solution et en films LbL pour la transfection de cellules et le contrôle des interactions cellule-surface. Il est possible de doser un agent de transfection et de l'ADN plasmidique dans des films LbL en ajustant le nombre de couches. Les efficacités de transfection avec différentes lignées cellulaires ont été au moins aussi bonnes que celles rapportées dans la littérature, mais sont restées globalement faibles. Différents nanobags ont également été systématiquement testés menant à un protocole de transfection très efficace avec une faible cytotoxicité pour des fibroblastes humains qui sont difficiles à transfecter. Nous avons pu identifier les architectures LbL qui permettent de contrôler l'adhésion cellulaire même en présence de sérum. Cela nous a permis d'introduire une nouvelle technique pour le suivi in situ de la transfection par QCM-D en suivant la mobilité du cytosquelette qui sera poursuivie dans un futur projet. / My PhD work was focused on polyelectrolyte complexes in bulk and in LbL-films for cell transfection and for controlling cell-surface interactions. It is possible to dose transfection agent and plasmid DNA in LbL-films by adjusting the number of layers. Transfection efficiencies with different cell lines were at least as good as reported in the literature, but remained overall weak. Different nanobags were also tested systematically leading to a highly efficient transfection protocol with low cytotoxicity for human fibroblasts which are difficult to transfect. We were able to identify multilayer architectures that allow to control cell adhesion even in the presence of serum. This allowed us also to introduce a new technique for the in-situ monitoring of transfection by QCM-D through monitoring cytoskeleton mobility which will be further pursued in a future research project.

During mitosis, adherent animal cells undergo a drastic shape change, from essentially flat to round, in a process known as mitotic cell rounding (MCR). The aim of this thesis was to critically examine the physical and biological basis of MCR. The experimental part of this thesis employed a combined optical microscope-atomic force microscope (AFM) setup in conjunction with flat tipless cantilevers to analyze cell mechanics, shape and volume. To this end, two AFM assays were developed: the constant force assay (CFA), which applies constant force to cells and measures the resultant height, and the constant height assay (CHA), which confines cell height and measures the resultant force. These assays were deployed to analyze the shape and mechanical properties of single cells trans-mitosis. The CFA results showed that cells progressing through mitosis could increase their height against forces as high as 50 nN, and that higher forces can delay mitosis in HeLa cells. The CHA results showed that mitotic cells confined to ~50% of their normal height can generate forces around 50-100 nN without disturbing mitotic progression. Such forces represent intracellular pressures of at least 200 Pascals and cell surface tensions of around 10 nN/µm. Using the CHA to compare mitotic cell rounding with induced cell rounding, it was observed that the intracellular pressure of mitotic cells is at least 3-fold higher than rounded interphase cells. To investigate the molecular basis of the mechanical changes inherent in mitotic cell rounding, inhibitors and toxins were used to pharmacologically dissect the role of candidate cellular processes. These results implicated the actomyosin cortex and osmolyte transporters, the most prominent of which is the Na+/H+ exchanger, in the maintenance of mechanical properties and intracellular hydrostatic pressure. Observations on blebbing cells under the cantilever supported the idea that the actomyosin cortex is required to sustain hydrostatic pressure and direct this pressure into cell shape changes. To gain further insight into the relationship between actomyosin activity and intracellular pressure, dynamic perturbation experiments were conducted. To this end, the CHA was used to evaluate the pressure and volume of mitotic cells before, during and after dynamic perturbations that included tonic shocks, influx of specific inhibitors, and exposure to pore-forming toxins. When osmotic pressure gradients were depleted, pressure and volume decreased. When the actomyosin cytoskeleton was abolished, cell volume increased while rounding pressure decreased. Conversely, stimulation of actomyosin cortex contraction triggered an increase in rounding pressure and a decrease in volume. Taken together, the dynamic perturbation results demonstrated that the actomyosin cortex contracts against an opposing intracellular pressure and that this relationship sets the surface tension, pressure and volume of the cell. The discussion section of this thesis provides a comprehensive overview of the physical basis of MCR by amalgamating the experimental results of this thesis with the literature. Additionally, the biochemal signaling pathways and proteins that drive MCR are collated and discussed. An exhaustive and unprecedented synthesis of the literature on cell rounding (approx. 750 papers as pubmed search hits on “cell rounding”, April 2012) reveals that the spread-to-round transition can be thought of in terms of a surface tension versus adhesion paradigm, and that cell rounding can be physically classified into four main modes, of which one is an MCR-like category characterized by increased actomyosin cortex tension and diminution of focal adhesions. The biochemical pathways and signaling patterns that correspond with these four rounding modes are catalogued and expounded upon in the context of the relevant physiology. This analysis reveals cell rounding as a pertinent topic that can be leveraged to yield insight into core principles of cell biophysics and tissue organization. It furthermore highlights MCR as a model problem to understand the adhesion versus cell surface tension paradigm in cells and its fundamentality to cell shape, mechanics and physiology.

La présentation de l’antigène est un mécanisme par lequel les cellules nucléées présentent un court peptide sur la molécule de classe 1 du Complexe Majeur d’Histocompatibilité (CMH-1) codée par les gènes « antigènes d’histocompatibilité humains ». Le terme “immunopeptidomique” est utilisé pour décrire l’ensemble des peptides associés aux molécules du CMH-1. Les cellules T CD8+ patrouillent l’organisme, s’attachent à la molécule CMH-1 par leur récepteur T et détruisent les cellules affichant un peptide atypique. Ce domaine présente un grand intérêt au niveau du traitement des infections virales et dans la conception de vaccins. Compte tenu que les coronavirus ont été à l’origine de trois épidémies durant les 20 dernières années, et que de multiples souches circulent chez l’humain ainsi que dans le règne animal, il est impératif de développer des vaccins universels qui pourrait prévenir de futurs événement épidémiologiques mondiaux reliés aux coronavirus. L’immunopeptidomique souffre d'un manque de protocoles normalisés et de contrôle et d’assurance de la qualité des échantillons afin de libérer tout son potentiel dans la recherche biomédicale. Dans le cadre de cette étude, la spectrométrie de masse, la cytométrie de flux et des approches bio-informatiques ont été utilisées pour développer des protocoles de contrôle de qualité pour la caractérisation de l’immunopeptidome de cellules infectées par les coronavirus. Nous avons isolé et analysé l’immunopeptidome de cellules MRC-5 avant et après infection par le coronavirus humain OC-43. En plus d’observer une forte baisse de l’abondance des molécules HLA et de la variété des peptides présentés après l’infection, 9 peptides viraux ont été isolés à partir des molécules du CMH-1. Ces peptides pourraient être utilisés afin de contribuer à formuler un vaccin pan-coronavirus qui élicite une réponse balancée entre la réponse humorale et la réponse cytotoxique. / Antigen presentation is a mechanism by which nucleated cells present a short peptide on the Major Histocompatibility Complex (MHC-1) class 1 molecule encoded by the “human histocompatibility antigen” genes. The term "immunopeptidomics" is used to describe the set of peptides associated with MHC-1 molecules. CD8+ T cells patrol the body, attach to the MHC-1 molecule through their T receptor and destroy cells displaying an atypical peptide. This field is of great interest in the treatment of viral infections and in vaccine design. Given that coronaviruses have been responsible for three epidemics in the last 20 years, and that multiple strains circulate in humans and animals, it is imperative to develop universal vaccines that could prevent future global epidemiological events related to coronaviruses. Immunopeptidomics suffers from a lack of standardized protocols and sample quality control and assurance to unleash its full potential in biomedical research. In this study, mass spectrometry, flow cytometry, and bioinformatics approaches were used to develop quality control protocols for characterizing the immunopeptidome of coronavirusinfected cells. We isolated and analyzed the immunopeptidome of MRC-5 cells before and after infection with human coronavirus OC-43. In addition to observing a strong decrease in the abundance of HLA molecules and in the variety of peptides presented after infection, 9 viral peptides were isolated from MHC-1 molecules. These peptides could be used to help formulate a pan-coronavirus vaccine that elicits a balanced response between humoral and cytotoxic responses.

INTRODUÇÃO: A hiperplasia adrenal macronodular independente de ACTH (AIMAH) é uma doença rara, caracterizada pela presença de macronódulos funcionantes nas adrenais e por uma produção aumentada, autônoma e sustentada de cortisol. Constitui uma causa incomum de síndrome de Cushing (SC). A forma esporádica da doença parece ser a mais frequente, no entanto, se desconhece a real prevalência de sua forma familial. Apesar de ser uma entidade clínica conhecida há quase 50 anos, o processo fisiopatológico que culminaria com a AIMAH, as alterações genéticas predisponentes e aspectos clínicos, laboratoriais e radiológicos relevantes da doença ainda não foram elucidados de forma clara. O diagnóstico recente de uma grande família portadora da doença viabilizou a realização do presente trabalho. OBJETIVOS: 1) Caracterizar a evolução da AIMAH em sua forma familial, correlacionando as manifestações clínicas, os dados laboratoriais e os achados radiológicos; 2) investigar a possível associação entre a AIMAH e a ocorrência de meningiomas intracranianos; 3) avaliar a atividade metabólica das adrenais hiperplasiadas na AIMAH; 4) definir o padrão de herança genética da doença na família estudada; e 5) mapear regiões cromossômicas e loci potencialmente relacionados à etiologia genética da AIMAH familial. MÉTODOS: 96 membros da família estudada foram inicialmente submetidos a uma avaliação clínica e laboratorial pormenorizada. Em seguida, foram realizados exames de tomografia computadorizada para a caracterização radiológica das adrenais. Exames de ressonância magnética e de tomografia por emissão de pósitrons com fluordesoxiglicose marcada, acoplada à tomografia computadorizada (18F-FDGPET/CT) foram realizados em pacientes com as formas familial e esporádica da doença para, respectivamente, investigar a presença de meningiomas intracranianos e caracterizar a atividade metabólica das adrenais hiperplasiadas. Foram também realizados testes in vivo para a pesquisa de receptores hormonais aberrantes nos pacientes com a forma familial da doença. Em uma outra etapa do estudo, diferentes técnicas de biologia molecular foram empregadas para a investigação da etiologia genética da AIMAH familial. Desta forma, realizou-se: o sequenciamento do gene do receptor do ACTH (MC2R), um estudo de ligação genética utilizando microssatélites específicos, um estudo de ligação genética em escala genômica utilizando polimorfismos de nucleotídeo único (SNPs) e o sequenciamento de genes suspeitos. RESULTADOS: A avaliação dos indivíduos pertencentes à genealogia permitiu o diagnóstico de 15 casos da doença (7 mulheres e 8 homens) em três gerações consecutivas. A AIMAH era transmitida para as gerações subsequentes tanto pelo sexo masculino como feminino e acometia cerca de metade dos irmãos em alguns segmentos da família. A idade média ao diagnóstico da doença foi de 52,8 +-11,3 anos (32 a 74 anos) e cerca de 86% (12/14) desses pacientes apresentavam SC subclínica. As dosagens do cortisol salivar à meia-noite e do cortisol em urina de 24 horas demonstraram baixa sensibilidade (21% e 14%, respectivamente) para o diagnóstico da doença em sua forma familial. O valor do ACTH plasmático encontrava-se baixo ( < 10 pg/mL) em 46% (5/11) dos pacientes doentes. Em cerca de 62% (8/13) dos casos, foi demonstrada uma redução do valor sérico do sulfato de desidroepiandrosterona (SDHEA). Por regressão logística simples, foi observado que a probabilidade (odds ratio) de um indivíduo apresentar a doença na família era maior diante da presença de pletora, após o diagnóstico de diabetes ou pré-diabetes ou diante do relato de ganho ponderal progressivo. O espessamento de ambas as adrenais associado à presença de nódulos bilaterais foi o achado radiológico mais frequente na forma familial da doença. No entanto, em um terço dos pacientes (5/15) foram encontradas alterações radiológicas em somente uma das adrenais. Durante os testes in vivo para pesquisa de receptores hormonais aberrantes, foram observadas, com frequência, respostas distintas entre os indivíduos doentes pertencentes à família. Nos pacientes submetidos ao exame de ressonância magnética, foram demonstradas imagens típicas de meningiomas intracranianos em um terço (5/15) dos casos. No exame 18F-FDG-PET/CT, foi observado um aumento da atividade metabólica das adrenais hiperplasiadas, tanto nos pacientes com SC manifesta como naqueles com a forma subclínica da doença. O estudo molecular permitiu delimitar nos cromossomos 16 e 11 algumas regiões genômicas potencialmente relacionadas à etiologia genética da AIMAH familial. O sequenciamento de alguns genes suspeitos (GPR56, GPR97 e GPR114), localizados nessas regiões, não demonstrou a presença de mutações. CONCLUSÕES: Na genealogia estudada, o padrão de transmissão da AIMAH foi autossômico dominante, e a SC subclínica foi a forma mais frequente de manifestação da doença. O teste de supressão com 1 mg de dexametasona via oral à meia-noite demonstrou ser o exame laboratorial de escolha para a avaliação inicial dos pacientes suspeitos de apresentarem AIMAH familial, em função, sobretudo, da baixa sensibilidade do cortisol salivar à meia-noite e do cortisol urinário para o diagnóstico da doença. Valores normais do ACTH plasmático foram um achado laboratorial frequente na AIMAH familial e valores baixos do SDHEA sérico demonstraram ser um indício relativamente precoce da SC subclínica associada à doença. Diferentes padrões radiológicos foram demonstrados nas tomografias das adrenais dos pacientes com AIMAH familial, não sendo infrequente a presença de assimetria entre as duas glândulas. Os resultados dos testes in vivo para a pesquisa de receptores hormonais aberrantes foram mais condizentes com a hipótese de que a expressão desses receptores seria um epifenômeno do processo fisiopatológico, resultante da proliferação e desdiferenciação celular. Uma alta prevalência de meningiomas intracranianos foi observada nos pacientes com AIMAH, tanto na forma familial da doença como na forma esporádica. Demonstrou-se também, pela primeira vez, que as adrenais na AIMAH podem exibir uma captação aumentada de 18F-FDG no exame de PET/CT, de forma semelhante às metástases e aos carcinomas da glândula. Por fim, foram delimitadas no cromossomo 16 (16p12.1, 16p11.2, 16q12.1, 16q13 e 16q21) e no cromossomo 11 (11q23.1) as principais regiões do genoma suspeitas de estarem ligadas à etiologia genética da AIMAH familial (genoma de referência: NCBI36/hg18) / INTRODUCTION: ACTH-independent macronodular adrenal hyperplasia (AIMAH) is a rare disease characterized by functioning adrenal macronodules and increased, autonomous and sustained cortisol production. This condition is an uncommon cause of Cushing\'s syndrome (CS). While the sporadic form of the disease appears to be the most frequent, the true prevalence of its familial form is unknown. Despite being a known clinical entity for almost 50 years, the pathophysiological process that leads to AIMAH, the predisposing genetic alterations and important clinical, laboratory and radiological aspects of the disease have not been fully clarified. The recent identification of a large group of relatives with familial AIMAH allowed the accomplishment of the present study. OBJECTIVES: The following were the aims of this study: 1) characterize the development of familial AIMAH through correlations between clinical manifestations, laboratory data and radiological findings; 2) investigate the possible association between AIMAH and the occurrence of intracranial meningioma; 3) characterize the metabolic activity of the adrenal glands in this disease; 4) define the inheritance pattern of the disease in the family studied; and 5) map chromosomal regions and loci potentially related to the genetic etiology of familial AIMAH. METHODS: 96 members of the family studied were initially subjected to a detailed clinical and laboratory evaluation. Computed tomography (CT) scans were performed for the radiological characterization of the adrenal glands. Magnetic resonance imaging scans and 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) scans were performed on patients with both forms of the disease (familial and sporadic) to investigate the presence of intracranial meningioma and characterize the metabolic activity of the adrenal glands, respectively. In vivo studies for aberrant hormone receptors were also conducted on those patients with familial AIMAH. In another phase of the study, different molecular biology techniques were employed to investigate the genetic etiology of familial AIMAH. For such, sequencing of the ACTH receptor gene (MC2R), a linkage study using specific microsatellite markers, a single nucleotide polymorphism (SNP)-based genome-wide linkage study and the sequencing of suspect genes were performed. RESULTS: The evaluation of the family revealed the diagnosis of 15 cases of the disease (7 women and 8 men) in three consecutive generations. AIMAH was transmitted to subsequent generations by both genders and half of the siblings were affected in some segments of the family. Mean age at diagnosis was 52.8 +-11.3 years (range: 32 to 74 years) and about 86% (12/14) of the patients exhibited subclinical CS. Both midnight salivary cortisol and 24-hour urinary cortisol demonstrated low sensitivity (21% and 14%, respectively) for the diagnosis of familial AIMAH. Plasma ACTH levels were low ( < 10 pg/ml) in 46% (5/11) of patients with the disease. In about 62% (8/13) of cases, serum dehydroepiandrosterone sulphate (DHEAS) levels were below the normal range. Simple logistic regression models revealed that the probability (odds ratio) of an individual having the disease in the family was greater in the presence of plethora, progressive weight gain or after the diagnosis of diabetes or prediabetes. Adrenal thickening associated with the presence of bilateral nodules was the most common radiological finding in familial AIMAH. However, radiological abnormalities were found in only one of the adrenal glands in one third of the patients (5/15). Throughout the in vivo studies for aberrant hormone receptors, distinct responses were frequently observed among the individuals with familial AIMAH. One third (5/15) of the patients who underwent magnetic resonance imaging scans had typical images of intracranial meningiomas. The 18F-FDG-PET/CT scan revealed increased metabolic activity of the hyperplastic adrenals in patients with both overt and subclinical CS. The molecular studies delimited genomic regions on chromosomes 16 and 11 potentially related to the genetic cause of familial AIMAH. Some suspected genes (GPR56, GPR97 and GPR114), located in these genomic regions, were sequenced, but no mutations were found. CONCLUSIONS: In the extended family studied, AIMAH followed an autosomal dominant pattern of inheritance and subclinical CS was the most common presentation of the disease. The 1 mg overnight dexamethasone suppression test proved to be the screening test of choice for the initial evaluation of patients suspected to have familial AIMAH, due mainly to the low sensitivity of midnight salivary cortisol and 24-hour urinary cortisol as screening tests. A normal level of plasma ACTH was a common laboratory finding in familial AIMAH. Low serum levels of DHEAS proved to be a relatively early finding associated with the subclinical CS determined by the disease. Adrenal CT scans revealed different radiological patterns among patients with familial AIMAH, with a fairly frequent rate of asymmetry between glands. The distinct responses observed throughout the in vivo studies for aberrant hormone receptors, among family members, favor the hypothesis that these receptors may be an epiphenomenon resulting from cell proliferation and dedifferentiation. An increased prevalence of intracranial meningioma was demonstrated in both the familial and sporadic forms of AIMAH. For the first time, it was shown that AIMAH may exhibit increased 18FFDG uptake on the PET/CT scan, similarly to adrenal carcinoma and metastasis. The main genomic regions potentially associated with familial AIMAH were delimited on chromosome 16 (16p12.1, 16p11.2, 16q12.1, 16q13 and 16q21) and chromosome 11 (11q23.1) (reference genome: NCBI36/hg18)

Thesis (Ph. D.)--Uniformed Services University of the Health Sciences, 2005. / Typescript (photocopy).

Thesis (Ph. D.)--Uniformed Services University of the Health Sciences, 2005. / Typescript (photocopy).

Abstract Cellular signaling by G protein-coupled receptors (GPCRs) governs a wide array of physiological functions throughout the body. The human δ-opioid receptor (hδOR) is a GPCR that modulates the sensation of pain and mood and has great potential for the treatment of pain and a variety of neurological disorders. A common single-nucleotide polymorphism (SNP) in the extracellular N-terminal tail of hδOR changes Phe to Cys at position 27. Using various biochemical and cell biological methods, the study demonstrates that several events during receptor biosynthesis and cell surface delivery are affected by the SNP. These events participate in the multifaceted regulation of the receptor and modulate receptor behavior at the cell surface. Two distinct pathways were shown to scrutinize the quality of the synthesized hδOR in the endoplasmic reticulum (ER) and target some for degradation in N-glycan-dependent and -independent ways. The hδORCys27 that matures inefficiently required N-glycan-mediated interactions with the lectin-chaperone calnexin to be expressed in a fully functional form at the cell surface, whereas the N-glycan-independent pathway was sufficient for hδORPhe27. For both variants, the N-glycan-independent quality control, which is likely to operate as a back-up pathway, led to a more rapid export from the ER and receptors at the cell surface that were less stable. Receptor dimerization emerged as an important regulatory step for receptor cell surface delivery. In co-transfected cells, interactions between the newly-synthesized variants led to the retention and subsequent ER-associated degradation of hδORPhe27. This dominant-negative attenuation of hδORPhe27 cell surface expression by hδORCys27 may have unpredictable consequences for opioid signaling in heterozygous individuals. Finally, the study shows that N-acetylgalactosamine (GalNAc)-type O-glycosylation catalyzed in the Golgi modulates hδOR expression at the cell surface by enhancing receptor stability and inhibiting constitutive downregulation. The modification of Ser residues in the receptor N-terminus by GalNAc-transferase 2 was affected by the SNP, which presents another distinction in the cellular processing of the two variants. The findings highlight the importance of the biosynthetic pathway in the regulation of GPCR behavior and pave way for strategies for treatments targeting GPCRs at this level. / Tiivistelmä Solujenvälisellä viestinnällä on keskeinen tehtävä kehon kaikissa toiminnoissa. δ-opioidireseptori (δOR) on solusignalointiin erikoistuneen kalvoproteiiniperheen (G-proteiiniin kytketyt reseptorit) jäsen, joka ohjaa kivuntuntemusta ja mielialoja. Sitä pidetään mahdollisena lääkekehityksen kohteena paitsi kivunlievityksen, myös useiden neurologisten häiriöiden hoidossa. δOR ilmenee kahtena polymorfisena muotona sen solunulkoisessa osassa tapahtuneen aminohappomuutoksen vuoksi (Phe27Cys). Työssä tutkittiin reseptorin glykosylaatiota ja dimerisaatiota, jotka säätelevät sen prosessointia, käyttäytymistä ja toimintaa. Käyttäen useita biokemiallisia ja solubiologisia menetelmiä työssä osoitettiin polymorfian vaikuttavan useisiin prosessointivaiheisiin ja muokkaavan siten reseptorin viestintää. Proteiinien laadunvalvontakoneiston havaittiin säätelevän reseptorin siirtymistä endoplasmakalvostolta solun pinnalle kahdella eri mekanismilla ohjaten osan reseptoreista hajotukseen. Toisin kuin Phe27-variantin, tehottomasti kypsyvän Cys27-variantin laadunvalvonta on riippuvainen reseptoriin liittyvistä N-glykaaneista ja näihin sitoutuvasta kaitsijaproteiinista, kalneksiinista. Reseptorivariantit, joista N-glykaanit puuttuvat, siirtyvät nopeammin solukalvolle, mutta ne ovat epästabiileja ja häviävät nopeasti solun pinnalta. Vaihtoehtoinen N-glykaaneista riippumaton laadunvalvontamekanismi sallii myös inaktiivisen Cys27-variantin pääsyn solun pinnalle. Varianttien dimerisoitumisen osoitettiin säätelevän niiden kuljetusta soluissa. Cys27-variantin havaittiin sitoutuvan Phe27-varianttiin aikaisessa biosynteesivaiheessa ja ohjaavan osan siitä hajotukseen. Tällä voi olla suuri merkitys opioidiviestinnässä molempia alleeleja kantavilla henkilöillä. Työssä havaittiin myös GalNAc-transferaasi-2-entsyymin ohjaavan Golgin laitteessa tapahtuvaa reseptorin O-glykosylaatiota. Se glykosyloi reseptorin solunulkoisen osan seriinitähteitä (Ser6, Ser25, Ser29), stabiloiden siten solun pinnan reseptoreita ja tehostaen niiden viestintää. Lisäksi havaittiin eroja varianttien O-glykosylaatiossa, mikä voi osaltaan selittää varianttien ilmentymisessä todettuja eroja. Tutkimus luo uutta tietoa biosynteesireitin merkityksestä G-proteiiniin kytkettyjen reseptorien säätelyssä sekä antaa pohjaa keinoille, joilla tätä voitaisiin hyödyntää farmakologisesti.

INTRODUÇÃO: A hiperplasia adrenal macronodular independente de ACTH (AIMAH) é uma doença rara, caracterizada pela presença de macronódulos funcionantes nas adrenais e por uma produção aumentada, autônoma e sustentada de cortisol. Constitui uma causa incomum de síndrome de Cushing (SC). A forma esporádica da doença parece ser a mais frequente, no entanto, se desconhece a real prevalência de sua forma familial. Apesar de ser uma entidade clínica conhecida há quase 50 anos, o processo fisiopatológico que culminaria com a AIMAH, as alterações genéticas predisponentes e aspectos clínicos, laboratoriais e radiológicos relevantes da doença ainda não foram elucidados de forma clara. O diagnóstico recente de uma grande família portadora da doença viabilizou a realização do presente trabalho. OBJETIVOS: 1) Caracterizar a evolução da AIMAH em sua forma familial, correlacionando as manifestações clínicas, os dados laboratoriais e os achados radiológicos; 2) investigar a possível associação entre a AIMAH e a ocorrência de meningiomas intracranianos; 3) avaliar a atividade metabólica das adrenais hiperplasiadas na AIMAH; 4) definir o padrão de herança genética da doença na família estudada; e 5) mapear regiões cromossômicas e loci potencialmente relacionados à etiologia genética da AIMAH familial. MÉTODOS: 96 membros da família estudada foram inicialmente submetidos a uma avaliação clínica e laboratorial pormenorizada. Em seguida, foram realizados exames de tomografia computadorizada para a caracterização radiológica das adrenais. Exames de ressonância magnética e de tomografia por emissão de pósitrons com fluordesoxiglicose marcada, acoplada à tomografia computadorizada (18F-FDGPET/CT) foram realizados em pacientes com as formas familial e esporádica da doença para, respectivamente, investigar a presença de meningiomas intracranianos e caracterizar a atividade metabólica das adrenais hiperplasiadas. Foram também realizados testes in vivo para a pesquisa de receptores hormonais aberrantes nos pacientes com a forma familial da doença. Em uma outra etapa do estudo, diferentes técnicas de biologia molecular foram empregadas para a investigação da etiologia genética da AIMAH familial. Desta forma, realizou-se: o sequenciamento do gene do receptor do ACTH (MC2R), um estudo de ligação genética utilizando microssatélites específicos, um estudo de ligação genética em escala genômica utilizando polimorfismos de nucleotídeo único (SNPs) e o sequenciamento de genes suspeitos. RESULTADOS: A avaliação dos indivíduos pertencentes à genealogia permitiu o diagnóstico de 15 casos da doença (7 mulheres e 8 homens) em três gerações consecutivas. A AIMAH era transmitida para as gerações subsequentes tanto pelo sexo masculino como feminino e acometia cerca de metade dos irmãos em alguns segmentos da família. A idade média ao diagnóstico da doença foi de 52,8 +-11,3 anos (32 a 74 anos) e cerca de 86% (12/14) desses pacientes apresentavam SC subclínica. As dosagens do cortisol salivar à meia-noite e do cortisol em urina de 24 horas demonstraram baixa sensibilidade (21% e 14%, respectivamente) para o diagnóstico da doença em sua forma familial. O valor do ACTH plasmático encontrava-se baixo ( < 10 pg/mL) em 46% (5/11) dos pacientes doentes. Em cerca de 62% (8/13) dos casos, foi demonstrada uma redução do valor sérico do sulfato de desidroepiandrosterona (SDHEA). Por regressão logística simples, foi observado que a probabilidade (odds ratio) de um indivíduo apresentar a doença na família era maior diante da presença de pletora, após o diagnóstico de diabetes ou pré-diabetes ou diante do relato de ganho ponderal progressivo. O espessamento de ambas as adrenais associado à presença de nódulos bilaterais foi o achado radiológico mais frequente na forma familial da doença. No entanto, em um terço dos pacientes (5/15) foram encontradas alterações radiológicas em somente uma das adrenais. Durante os testes in vivo para pesquisa de receptores hormonais aberrantes, foram observadas, com frequência, respostas distintas entre os indivíduos doentes pertencentes à família. Nos pacientes submetidos ao exame de ressonância magnética, foram demonstradas imagens típicas de meningiomas intracranianos em um terço (5/15) dos casos. No exame 18F-FDG-PET/CT, foi observado um aumento da atividade metabólica das adrenais hiperplasiadas, tanto nos pacientes com SC manifesta como naqueles com a forma subclínica da doença. O estudo molecular permitiu delimitar nos cromossomos 16 e 11 algumas regiões genômicas potencialmente relacionadas à etiologia genética da AIMAH familial. O sequenciamento de alguns genes suspeitos (GPR56, GPR97 e GPR114), localizados nessas regiões, não demonstrou a presença de mutações. CONCLUSÕES: Na genealogia estudada, o padrão de transmissão da AIMAH foi autossômico dominante, e a SC subclínica foi a forma mais frequente de manifestação da doença. O teste de supressão com 1 mg de dexametasona via oral à meia-noite demonstrou ser o exame laboratorial de escolha para a avaliação inicial dos pacientes suspeitos de apresentarem AIMAH familial, em função, sobretudo, da baixa sensibilidade do cortisol salivar à meia-noite e do cortisol urinário para o diagnóstico da doença. Valores normais do ACTH plasmático foram um achado laboratorial frequente na AIMAH familial e valores baixos do SDHEA sérico demonstraram ser um indício relativamente precoce da SC subclínica associada à doença. Diferentes padrões radiológicos foram demonstrados nas tomografias das adrenais dos pacientes com AIMAH familial, não sendo infrequente a presença de assimetria entre as duas glândulas. Os resultados dos testes in vivo para a pesquisa de receptores hormonais aberrantes foram mais condizentes com a hipótese de que a expressão desses receptores seria um epifenômeno do processo fisiopatológico, resultante da proliferação e desdiferenciação celular. Uma alta prevalência de meningiomas intracranianos foi observada nos pacientes com AIMAH, tanto na forma familial da doença como na forma esporádica. Demonstrou-se também, pela primeira vez, que as adrenais na AIMAH podem exibir uma captação aumentada de 18F-FDG no exame de PET/CT, de forma semelhante às metástases e aos carcinomas da glândula. Por fim, foram delimitadas no cromossomo 16 (16p12.1, 16p11.2, 16q12.1, 16q13 e 16q21) e no cromossomo 11 (11q23.1) as principais regiões do genoma suspeitas de estarem ligadas à etiologia genética da AIMAH familial (genoma de referência: NCBI36/hg18) / INTRODUCTION: ACTH-independent macronodular adrenal hyperplasia (AIMAH) is a rare disease characterized by functioning adrenal macronodules and increased, autonomous and sustained cortisol production. This condition is an uncommon cause of Cushing\'s syndrome (CS). While the sporadic form of the disease appears to be the most frequent, the true prevalence of its familial form is unknown. Despite being a known clinical entity for almost 50 years, the pathophysiological process that leads to AIMAH, the predisposing genetic alterations and important clinical, laboratory and radiological aspects of the disease have not been fully clarified. The recent identification of a large group of relatives with familial AIMAH allowed the accomplishment of the present study. OBJECTIVES: The following were the aims of this study: 1) characterize the development of familial AIMAH through correlations between clinical manifestations, laboratory data and radiological findings; 2) investigate the possible association between AIMAH and the occurrence of intracranial meningioma; 3) characterize the metabolic activity of the adrenal glands in this disease; 4) define the inheritance pattern of the disease in the family studied; and 5) map chromosomal regions and loci potentially related to the genetic etiology of familial AIMAH. METHODS: 96 members of the family studied were initially subjected to a detailed clinical and laboratory evaluation. Computed tomography (CT) scans were performed for the radiological characterization of the adrenal glands. Magnetic resonance imaging scans and 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG-PET/CT) scans were performed on patients with both forms of the disease (familial and sporadic) to investigate the presence of intracranial meningioma and characterize the metabolic activity of the adrenal glands, respectively. In vivo studies for aberrant hormone receptors were also conducted on those patients with familial AIMAH. In another phase of the study, different molecular biology techniques were employed to investigate the genetic etiology of familial AIMAH. For such, sequencing of the ACTH receptor gene (MC2R), a linkage study using specific microsatellite markers, a single nucleotide polymorphism (SNP)-based genome-wide linkage study and the sequencing of suspect genes were performed. RESULTS: The evaluation of the family revealed the diagnosis of 15 cases of the disease (7 women and 8 men) in three consecutive generations. AIMAH was transmitted to subsequent generations by both genders and half of the siblings were affected in some segments of the family. Mean age at diagnosis was 52.8 +-11.3 years (range: 32 to 74 years) and about 86% (12/14) of the patients exhibited subclinical CS. Both midnight salivary cortisol and 24-hour urinary cortisol demonstrated low sensitivity (21% and 14%, respectively) for the diagnosis of familial AIMAH. Plasma ACTH levels were low ( < 10 pg/ml) in 46% (5/11) of patients with the disease. In about 62% (8/13) of cases, serum dehydroepiandrosterone sulphate (DHEAS) levels were below the normal range. Simple logistic regression models revealed that the probability (odds ratio) of an individual having the disease in the family was greater in the presence of plethora, progressive weight gain or after the diagnosis of diabetes or prediabetes. Adrenal thickening associated with the presence of bilateral nodules was the most common radiological finding in familial AIMAH. However, radiological abnormalities were found in only one of the adrenal glands in one third of the patients (5/15). Throughout the in vivo studies for aberrant hormone receptors, distinct responses were frequently observed among the individuals with familial AIMAH. One third (5/15) of the patients who underwent magnetic resonance imaging scans had typical images of intracranial meningiomas. The 18F-FDG-PET/CT scan revealed increased metabolic activity of the hyperplastic adrenals in patients with both overt and subclinical CS. The molecular studies delimited genomic regions on chromosomes 16 and 11 potentially related to the genetic cause of familial AIMAH. Some suspected genes (GPR56, GPR97 and GPR114), located in these genomic regions, were sequenced, but no mutations were found. CONCLUSIONS: In the extended family studied, AIMAH followed an autosomal dominant pattern of inheritance and subclinical CS was the most common presentation of the disease. The 1 mg overnight dexamethasone suppression test proved to be the screening test of choice for the initial evaluation of patients suspected to have familial AIMAH, due mainly to the low sensitivity of midnight salivary cortisol and 24-hour urinary cortisol as screening tests. A normal level of plasma ACTH was a common laboratory finding in familial AIMAH. Low serum levels of DHEAS proved to be a relatively early finding associated with the subclinical CS determined by the disease. Adrenal CT scans revealed different radiological patterns among patients with familial AIMAH, with a fairly frequent rate of asymmetry between glands. The distinct responses observed throughout the in vivo studies for aberrant hormone receptors, among family members, favor the hypothesis that these receptors may be an epiphenomenon resulting from cell proliferation and dedifferentiation. An increased prevalence of intracranial meningioma was demonstrated in both the familial and sporadic forms of AIMAH. For the first time, it was shown that AIMAH may exhibit increased 18FFDG uptake on the PET/CT scan, similarly to adrenal carcinoma and metastasis. The main genomic regions potentially associated with familial AIMAH were delimited on chromosome 16 (16p12.1, 16p11.2, 16q12.1, 16q13 and 16q21) and chromosome 11 (11q23.1) (reference genome: NCBI36/hg18)