O hepatoblastoma é uma neoplasia embrionária hepática que ocorre na faixa pediátrica, rara, sendo bastante heterogênea devido aos seus diferentes componentes epiteliais e mesenquimais. Pouco ainda se sabe a respeito de sua patogênese. Utilizando um microscópio de captura a laser foram dissecadas áreas de componente epitelial do hepatoblastoma e áreas de tecido hepático adjacente não acometido. Destas amostras obtidas de pacientes não submetidos ao tratamento prévio, foram extraídos RNA e confeccionados cDNA microarrays, para análise comparativa da expressão gênica, seguida de validação por método imunohistoquímico de alguns genes selecionados. Comparando neoplasia e tecido hepático em duas amostras criopreservadas foram identificados 70 genes diferencialmente expressos, sendo 19 hiperexpressos e 51 hipoexpressos no tumor. A maioria dos genes encontrados foi mapeada nos cromossomos 1 e 2. Dos genes selecionados para validação por método imuno-histoquímico, destacaram-se o receptor de Insulina e o TFE3 (genes hipoexpressos no cDNA microarray). A imunomarcação para o receptor de insulina foi positiva tanto no tecido hepático não acometido quanto no componente epitelial fetal do hepatoblastoma , mas foi consistentemente negativa nas amostras de componente embrionário (9/9). A imunomarcação para o TFE3 foi positiva no tecido hepático não acometido, e nos componentes epitelial fetal e embrionário, em proporção variável das células com expressão mais intensa no componente embrionário. As reações imuno-histoquímicas para os outros genes selecionados não permitiram interpretação conclusiva. A alta proporção dos genes diferencialmente expressos localizados nos cromossomos 1 e 2 reflete os achados citogenéticos relatados na literatura relacionada ao hepatoblastoma . Achados de imunoexpressão de proteínas relacionadas aos genes TFE3 e receptor de insulina no tecido hepático e nos diferentes componentes do hepatoblastoma são inéditos e sugerem participação da via sinalizadora da insulina na patogênese destes tumores / Hepatoblastoma is a rare tumor, and little is known about its pathogenesis and genetic alterations. Using a laser capture microdissection microscope we sampled areas of epithelial component of hepatoblastoma prior chemotherapy and their normal liver counterpart in order to perform the comparative gene expression analysis followed by the validation of selected genes by immunohistochemistry. Comparing tumor and non-diseased liver in two frozen samples, 70 differentially expressed genes were found, 19 overexpressed and 51 underexpressed in the tumor. Most of the genes were located at chromosomes 1 and 2. Of the genes selected for validation by immunohistochemistry, the most interesting findings came from Insulin receptor and TFE3 (both underexpressed genes). Insulin receptor was positive in non diseased liver and in the fetal component of the Hepatoblastoma but was consistently negative in the embryonal component (9/9 cases). The TFE3 staining was positive in the normal liver and fetal and embryonal components of the tumor in variable proportion of the cells, more marked in the embryonal component. The higher proportion of genes located at chromosomes 1 and 2 corroborates the cytogenetics findings reported in the literature related to Hepatoblastoma . The immunohistochemistry findings of different expression of insulin receptor in the fetal and embryonal components of Hepatoblastoma and the positivity of TFE3 in normal liver and in the tumors epithelial components deserves further investigation regarding the role of these genes to the pathogenesis of Hepatoblastoma

Orientadores: Ricardo Barini, Lourenço Sbragia Neto / Tese (doutorado) - Universidade Estadual de Campinas. Faculdade de Ciencias Medicas / Made available in DSpace on 2018-11-27T12:29:22Z (GMT). No. of bitstreams: 1 Bueno_MarciaPereira_D.pdf: 2898828 bytes, checksum: 2c6dcaa4a20ec185bea4b47114c30a0e (MD5) Previous issue date: 2010 / Resumo: A restrição do crescimento intrauterino (RCIU) limita o desenvolvimento fetal adequado aumentando a morbidade e mortalidades perinatais. Os mecanismos fetais adaptativos na RCIU podem desencadear alterações endócrinas e metabólicas que explicariam a ocorrência de doenças na idade adulta. O objetivo do estudo foi avaliar na RCIU experimental pela ligadura da artéria uterina se existem alterações na morfometria e histologia do fígado, intesti no e rins e se existem diferenças na expressão dos receptores de insulina, IR-(3, IRS-1, IRS-2, IGF-IR(3 no grupo de fetos submetidos à RCIU. O presente experimento foi submetido ao Comitê de Ética e Experimentação Animal da Universidade Estadual de Campinas (CEEA-UNICAMP) e aprovado como projeto de pesquisa N° 1644-1. Para realização do estudo utilizamos fetos de ratas Sprague Dawley divididos em 3 grupos. Grupo I (RCIU) - 40 fetos submetidos à ligadura da artéria uterina unilateral com 18,5 dias de gestação, Grupo II (Controle-RCIU) - 40 fetos do corno oposto ao da ligadura da artéria uterina e Grupo III (Controle Externo) - 40 fetos sem procedimento cirúrgico ou alimentar. Os resultados mostraram no modelo experimental de RCIU uma diminuição do peso corporal (PC), hepático (PH) e intestinal (PI) (p<0,01) no grupo RCIU, as relações entre PH/PC, PI/PC, PR/PC foram mantidas, fetos RC IU tem diminuição das camadas submucosas e mucosas intestinais (p<0,05); diminuição da camada cortical renal e do número de glomérulos, com aumento do volume glomerular (p<0,05). Na RCIU encontramos menor expressão hepática do IR-(3, IRS-1 e IRS-2, menor expressão do IRS-2 no intestino e rins e maior expressão do IGF-IR(3 em todos os tecidos. O modelo experimental estudado causou uma RCIU simétrica com alterações morfométricas e do metabolismo da glicose que poderiam justificar no futuro um maior risco de doenças metabólicas / Abstract: Intrauterine growth restriction (IUGR) limits appropriate fetal development increasing morbidity and perinatal mortality. Adaptive mechanisms in fetal IUGR may leave to endocrine and metabolic alterations that could explain the occurrence of diseases in adulthood. The aim of this study was to evaluate whether experimental IUGR by uterine artery ligation causes changes in morphology and histology of the liver, intestines and kidneys. We also evaluated if there were differences in the expression of insulin receptors, IR-(3, IRS-1, IRS-2, IGF-IR(3 of fetuses subjected to IUGR. This experiment was submitted to the Ethics and Animal Experimentation of the Campinas State University (UNICAMP CEEA) and was approved as a research project No. 1644-1. The study used fetuses Sprague-Dawley rats divided into 3 groups. Group I (IUGR) - 40 fetuses who underwent uterine artery ligation sided with 18.5 days of pregnancy Group II (Control-IUGR) - 40 fetuses of the horn opposite to the uterine artery ligation, and Group III (External Control) - 40 fetuses without surgery or food The results showed the experimental model of IUGR, a reduction in body weight (BW), liver (PH) and intestine (PI) (p <0.01) in IUGR, the relationship between PH/PC, PI/PC, PR/PC have been retai ned, IUGR fetuses have reduced layers of the intestinal mucosa and submucosa (p<0,05), decreased renal cortical layer and the glomerular number and increased volume rate (p<0,05). In IUGR found lower hepatic expression of IR-(3, IRS-1 and IRS-2, reduced expression of IRS-2 in the intestine and kidney and increased expression of IGF-IR(3 in all tissues. The experimental model studied caused a symmetrical IUGR with histological changes and glucose metabolism that could justify a greater risk of metabolic diseasesin the future / Doutorado / Ciencias Biomedicas / Doutor em Tocoginecologia

Migraine is a common, debilitating neurovascular disease charactensed by severe recurrent headache, nausea and vomiting, photophobia and phonophobia. It is clinically diagnosed based on criteria specified by the International Headache Society (IHS), defining two major classes of migraine: migraine with aura (MA) and migraine without aura (MO) MA sufferers experience neurovascular disturbances that precede the headache phase of an attack. Although migraine is partly influenced by environmental determinants, there is a significant genetic component, with disease heritability estimated to be up to 60% and mode of transmission multifactorial. The disorder is common with a large Dutch study reporting lifetime prevalence estimates of 33% in women and 13.3% in men, with an earlier study estimating 24% of women and 12% of men in the overall population. Mutations in various ion channel genes are responsible for neuromuscular and other neurological disorders. Inherited ion channel mutations or 'channelopathies' are increasingly found to be the cause of various neurological disorders in humans. In familial hemiplegic migraine (FHM), a rare subtype of migraine with aura, mutations in the CACNA1A gene (localised at C19p13) have been fbund (FHM1). This gene codes for the alphalA subunit of the neuronal voltage-dependent P/Q-type calcium channel. Recently a second gene, ATP1A2 (FHM2) (localised at C1q23), was implicated in some EHM families. The ATP1A2 ion channel gene, codes for the alpha2 subunit of the Na+, K+ ion ATPase pump. These findings of mutations in these genes have focused attention on central nervous system ionic channels and helped to better understand EHM pathophysiology, where the best genetic evidence providing molecular insight into migraine still comes flom the mutations detected in the rare form of migraine with aura; FHM. Migraine family studies, at the Genomic Research Centre (GRC), have utilised linkage analysis methods in providing results that have indicated suggestive linkage to the FHM1-CACNA1A region on l9p13, in a large multigenerational family (Migraine Family 1; MEl) affected with typical migraine. Also linkage studies conducted within the GRC have implicated an additional susceptibility region on chromosome 1q31, but still not ruling out a second susceptibility region on C1q23, with the possibility of there being two distinct loci, on the chromosome lq region. The focus of research in this thesis is on two main chromosomal regions, which were tested for migraine susceptibility on chromosome 1 and chromosome 19. The research involved a cross-disciplinary approach utilising association, linkage and mutation screening approaches. Allelic candidate gene studies can provide a suitable method for locating genes of small effect that contribute to complex genetic disorders, such as migraine. Family linkage studies are useful for detection of chromosomal susceptibility regions and association studies are powerful when a plausible candidate gene and a sequence variant with potential functional relevance is examined. Mutation screening studies can indicate a direct cause of disorders such as migraine, where possible sequence variants may alter the translation of proteins in genes, causing the disease. The first gene exanted on chromosome 19 was that of the Low Density Lipoprotein Receptor (LDLR) gene. The LDLR gene is a cell surface receptor that plays an important role in cholesterol homeostasis. We investigated the (TA)n polymorphism in exon 18 of the LDLR gene on chromosome l9pl3.2 performing an association analysis in 244 typical migraine affected patients, 151 suffering from migraine with aura, 96 with migraine without aura and 244 unaffected controls. The populations consisted of Caucasians only and controls were age and sex matched. The results showed no significant difference between groups for allele frequency distributions of the (TA)n polymorphism even after separation of the migraine affected individuals into subgroups of MA and MO affected patients. This is in contradiction to Mochi et al, 2003 who found a positive association of this variant with MO. Our study discusses possible differences between the two studies and extends this research by investigating circulating cholesterol levels in a migraine affected genetically-isolated population. Another gene examined on chromosome l9pl3 was the insulin receptor gene (1NSR). The aim of this study was to investigate through direct sequencing the INSR gene in DNA samples from a migraine affected family previously showing linkage to chromosome l9pl3 in an attempt to detect disease associated mutations. The insulin receptor gene (INSR) on chromosome 19pl3.3-13.2 is a gene of interest since a number of SNPs located within the gene have been implicated in migraine with (MA) and without aura (MO). Six DNA samples obtained from non-founding migraine affected members of migraine family one (MF 1) were used in this study. Genomic DNA was sequenced for the 1NSR gene in exons 1-22 and the promoter region. In the six migraine family member samples, previously reported single nucleotide polymorphisms (SNP5) were detected within two exonic DNA coding regions of the INSR gene. These SNPs, in exon 13 and 17, do not alter the normal INSR polypeptide sequence. In addition, intron 7 also revealed a DNA base sequence variation. For the 5' untranslated promoter region of the gene, no mutations were detected. In conclusion, this study detected no INSR mutations in affected members of a chromosome 19 linked migraine pedigree. Hence, migraine linkage to this chromosomal region may involve other candidate genes. The NOTCH3 gene on C19p13.2-p13.l has previously been shown to be a gene involved in cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) and may also be implicated in migraine as there are some symptom similarities between the two disorders. The TNFSF7 gene localised on Cl9pl3 is homologous to the ligands of the TNF receptor family, including TNF-alpha and TNF-beta, genes that have both been previously associated with migraine. This study investigated the migraine susceptibility locus at Cl9p13 studying two genes that may be involved in the disorder. The NOTCH3 gene was analysed by sequencing all exons with known CADASIL mutations in a family (MF1) that has previously been shown to be linked to Cl9pl3. The sequencing results for affected members of this pedigree proved to be negative for all known sequence variants giving rise to mutation causing amino acid changes for CADASIL. The direct sequencing results displayed that of a normal coding sequence for the NOTCH3 gene F or the TNFSF7 gene, this was investigated through SNP association analysis using a matched case-control migraine diagnosed population. Chi-square results showed non-significant P values across all populations tested against controls except for the MO subgroup which displayed a weak association with the TNFSF7 SNP (genotype, allele analysis P = 0.036, P = 0 017 respectively). Our results suggest that common migraine is not caused by any known CADASIL mutations in the NOTCH3 gene of interest however, the TNFSF7 gene displayed signs of involvement in a MO affected population, but, further studies are needed to confirm these results and to further explore a TNF receptor - migraine potential interaction. A final examination on chromosome 19 involved a case report of an extremely rare and severe form of migraine. As stated earlier Familial Hemiplegic Migraine (FHM) is a severe rare sub-type of migraine and gene mutations on chromosome 19 have been identified in the calcium channel gene CACNA1A (Cl9pl3) fOr FHM. Recently a gene mutation (S218L) for a dramatic syndrome originating from FHM, commonly named 'migraine coma', has implicated exon 5 of the CACNA1A gene. The occurrence of trivial head trauma, in FHM patients, may also be complicated by severe, sometimes even fatal, cerebral edema and coma occurring after a lucid interval. Hemiplegic migraine has also been found to be sporadic in which both forms share a similar spectrum of clinical presentations and genetic heterogeneity. The case report presented in this study enhances the involvement of the S218L CACNA1A mutation in the extremely rare disorder of minor head trauma induced migraine coma. It not only proves to be a powerful diagnostic tool in detecting cases of FHM head trauma induced coma but also for sporadic hemiplegic migraine (SHM) coma subjects. We conclude from this case study that the S218L mutation, in the CACNA1A calcium channel subunit gene, is involved in sporadic hemiplegic migraine (SHM), delayed cerebral edema and coma after minor head trauma. This thesis also involved analysis of chromosome 1 for migraine susceptibility, where FHM studies provided a foundation fOr common migraine research on chromosome 1. Studies have suggested that mutations in the CACNA1A gene on chromosome l9p cause FHM in only approximately 50% of affected pedigrees. The CACNAIA gene has previously been tested, within the Genomics Research Centre, in the common forms of migraine; however no new mutations or the FHM mutations were detected in these MA/MO affected samples. A second FHM susceptibility locus maps to chromosome 1q23 and mutations in the ATP1A2 gene have recently been implicated in two Cl-linked FHM pedigrees. As FHM is considered a rare and severe form of MA, it is possible that the chromosome 1q23 locus, and the ATP1A2 gene, may be involved in the common forms of migraine with (MA) and possibly without aura (MO). Also, we have previously reported evidence of linkage to microsatellite markers on chromosome 1q31 in a large pedigree affected predominately with MA, which suggests the possibility that there are two distinct loci for migraine susceptibility on chromosome 1. The objectives of this study were to extend our linkage analysis of chromosome lq microsatellite markers in predominantly migraine with aura pedigrees. Also, our aim was to test the novel FHM-2 ATP1A2 gene for involvement in these migraine affected pedigrees and a previous pedigree (Migraine Family 14; MF 14) showing evidence of linkage of markers to Clq31. This was performed by a chromosome 1 scan (31 markers) in 21 multiplex pedigrees affected mainly with MA. Also, the known FHM-2 ATP1A2 gene mutations were tested, by sequencing, fOr involvement in MA and MO in these pedigrees. Mutation screening by direct sequencing was also performed throughout the coding areas of the ATP1A2 gene in 3 MA individuals fiom MF14. The results of this study detected evidence for linkage in our migraine pedigrees at chromosome 1q23, to microsatellite markers spanning the ATP1A2 (FHM-2) gene. However testing of the known ATP1A2 gene mutations (for FHM) in migraine probands of pedigrees showing excess allele sharing was negative, with no mutations detected in these migraineurs. Sequencing of the entire coding areas of the gene through 3 MA affecteds from MF14, a pedigree showing significant linkage to this region, was also negative for mutations. In conclusion, this study reported that microsatellite markers on chromosome 1q23 show evidence of excess allele sharing in MA and some MO pedigrees, suggesting linkage to the common forms of migraine and the presence of a susceptibility gene in this region. The new FHM-2 (ATPIA2 gene) mutations reported by Fusco et al, 2003 do not cause migraine in probands of affected pedigrees showing excess allele sharing to markers in this genomic region. Also no mutations were detected in all exons of the ATP1A2 gene in 3 MA affected individuals from a large pedigree (MF14) showing linkage to this region. Investigation in this thesis continued on chromosome 1, with other genes being examined on C1q23, as well as the C1q31 region for a migraine susceptibility locus or gene. Previously in our laboratory, evidence for linkage was shown to migraine at C1q31 in one family predominantly affected with MA, with microsatellite markers in this region. The initial Cl study (above; ATP1A2 gene) has also provided evidence for linkage to the chromosome 1 locus 1q23, with evidence for excess allele sharing of markers in predominantly MA affected pedigrees. To further investigate both chromosome I loci, an investigation with six candidate genes that lie within the C1q23 and 1q31 regions through association analysis was undertaken. The results from this study reported non-significant chi-square results, showing P values greater than 0.05 across all SNPs (and a CA rpt) tested. An exception was the rs704326 SNP from exon 43 of the CACNA1E gene on C1q31. P values significantly less than 0.001 were obtained in the total migraine population and the MA subgroup, with similar frequency comparisons ascertained in both genotype and allele analysis. Examination through contingency table analysis of the CACNA1E flequency data indicated that the risk allele (A) was over-represented in the migraine group compared to the control group. Further comparison of the genotype data indicated a difference in frequency distributions (P less than 0 0001). Stratified analyses of migraine subtypes indicated that this association was specifically attributed to the MA subtype group. Odds ratios produced an OR of 4.14 with a 95% CI of 2.36 - 7.26 (P less than 0.0001). The positive association results obtained within the CACNA1E gene are interesting in the fact that FHM is considered to be a rare and severe form of migraine with aura (MA) and FHM-1 is caused by mutations contained within the calcium channel gene CACNA1A (localized at Cl9p13). The idea that FHM and specifically an FHM gene in the C1q31 genomic region may also contribute to susceptibility to the more common forms of migraine i e. migraine with aura, strongly supports and reinforces the idea that a common defective gene may be influencing both FHM and typical migraine. In conclusion, this thesis undertook a cross-disciplinary approach to genetic research of a complex disorder. The research involved linkage, association and mutation analysis strategies of migraine. This research implicated a specific variant on chromosome 1 and further supported the heterogeneic nature of migraine. Future directions into migraine research should involve further investigation of this specific variant and this genomic region. Such studies may aid in the development of more precise diagnosis and treatment methods for this complex disorder.

Activation of the Unfolded Protein Response (UPR) following stress in the Endoplasmic Reticulum (ER) is an important mechanism by which obesity results in insulin resistance and type II diabetes. We uncovered a role for the adaptor protein Nck in modulating the UPR. In this study, we report that obese Nck1-/- mice, which show lower levels of UPR in liver and adipose tissue, present improved insulin signalling in these tissues. We established that the effect of Nck1 is cell autonomous by showing that HepG2 cells treated with Nck1 siRNA have reduced ER stress-induced UPR and Insulin Receptor Substrate-1 (IRS-1) serine phosphorylation. In these cells, we observed that the IRS-1 levels and activation of signalling components downstream of the insulin receptor were increased. This correlates with enhanced cell survival to stress and insulin stimulated glycogen synthesis. Overall, we demonstrated that Nck1 participates in ER-stress-induced insulin resistance and regulation of IRS-1-dependent signalling.

O hepatoblastoma é uma neoplasia embrionária hepática que ocorre na faixa pediátrica, rara, sendo bastante heterogênea devido aos seus diferentes componentes epiteliais e mesenquimais. Pouco ainda se sabe a respeito de sua patogênese. Utilizando um microscópio de captura a laser foram dissecadas áreas de componente epitelial do hepatoblastoma e áreas de tecido hepático adjacente não acometido. Destas amostras obtidas de pacientes não submetidos ao tratamento prévio, foram extraídos RNA e confeccionados cDNA microarrays, para análise comparativa da expressão gênica, seguida de validação por método imunohistoquímico de alguns genes selecionados. Comparando neoplasia e tecido hepático em duas amostras criopreservadas foram identificados 70 genes diferencialmente expressos, sendo 19 hiperexpressos e 51 hipoexpressos no tumor. A maioria dos genes encontrados foi mapeada nos cromossomos 1 e 2. Dos genes selecionados para validação por método imuno-histoquímico, destacaram-se o receptor de Insulina e o TFE3 (genes hipoexpressos no cDNA microarray). A imunomarcação para o receptor de insulina foi positiva tanto no tecido hepático não acometido quanto no componente epitelial fetal do hepatoblastoma , mas foi consistentemente negativa nas amostras de componente embrionário (9/9). A imunomarcação para o TFE3 foi positiva no tecido hepático não acometido, e nos componentes epitelial fetal e embrionário, em proporção variável das células com expressão mais intensa no componente embrionário. As reações imuno-histoquímicas para os outros genes selecionados não permitiram interpretação conclusiva. A alta proporção dos genes diferencialmente expressos localizados nos cromossomos 1 e 2 reflete os achados citogenéticos relatados na literatura relacionada ao hepatoblastoma . Achados de imunoexpressão de proteínas relacionadas aos genes TFE3 e receptor de insulina no tecido hepático e nos diferentes componentes do hepatoblastoma são inéditos e sugerem participação da via sinalizadora da insulina na patogênese destes tumores / Hepatoblastoma is a rare tumor, and little is known about its pathogenesis and genetic alterations. Using a laser capture microdissection microscope we sampled areas of epithelial component of hepatoblastoma prior chemotherapy and their normal liver counterpart in order to perform the comparative gene expression analysis followed by the validation of selected genes by immunohistochemistry. Comparing tumor and non-diseased liver in two frozen samples, 70 differentially expressed genes were found, 19 overexpressed and 51 underexpressed in the tumor. Most of the genes were located at chromosomes 1 and 2. Of the genes selected for validation by immunohistochemistry, the most interesting findings came from Insulin receptor and TFE3 (both underexpressed genes). Insulin receptor was positive in non diseased liver and in the fetal component of the Hepatoblastoma but was consistently negative in the embryonal component (9/9 cases). The TFE3 staining was positive in the normal liver and fetal and embryonal components of the tumor in variable proportion of the cells, more marked in the embryonal component. The higher proportion of genes located at chromosomes 1 and 2 corroborates the cytogenetics findings reported in the literature related to Hepatoblastoma . The immunohistochemistry findings of different expression of insulin receptor in the fetal and embryonal components of Hepatoblastoma and the positivity of TFE3 in normal liver and in the tumors epithelial components deserves further investigation regarding the role of these genes to the pathogenesis of Hepatoblastoma

Myotonic Dystrophy Type I (DM1) is a multi-systemic genetic neuromuscular degenerative disease, has a prevalence in most populations of about 1:8000 and is caused by the nuclear retention of pathogenically expanded DMPK mRNA. A previous DM1 RNAi-kinome screen in our lab has identified kinases that reduced both count and area of DMPK mRNA foci in vitro. One such discovered kinase is PACT, which has showed to decrease foci count and area in DM1 fibroblasts by 30-50%. This study explored PACT as well as binding partner DICER involved in cellular RNA processing machinery, to highlight potential therapeutic targets in DM1. DM1 fibroblasts treated with PACT siRNA showed a non-significant trend of upregulation in MBNL1 mRNA and protein expression. PACT knockdown also showed trend of missplicing normalization in SERCA-1, more prominently seen in DM1-2000 human fibroblasts, whereas IR (insulin receptor) splicing remained unaffected. On the other hand, DICER knockdown did not have profound affect on foci integrity as well as MBNL1 RNA and protein xpressions in DM1 fibroblasts. SERCA-1 splicing in DICER siRNA treated samples also remained unchanged. We report here our findings in pursuit of potential therapeutic targets for the treatment of DM1.

Insulin receptor is a multi-domain signalling protein acting as a dimer. It comprises an extracellular ectodomain, a transmembrane domain and intracellular tyrosine kinase domain. Upon insulin binding, conformational changes in insulin as well as in insulin receptor occur and trigger the signaling cascade via the kinase domain. Abnormalities in insulin and insulin receptor function cause diabetes mellitus, a widespread disorder which can be consequence of genetic factors as well as lifestyle and is manifested by increased level of blood glucose. A common treatment of diabetes mellitus is via insulin analogues with different molecular properties. Insulin/insulin receptor interactions in the binding pocket are divided into two groups, so-called "site1" and "site2". The molecular details of the interactions in site1 are well known, while site2 residues are still not completely elucidated. It is important to shed light on the binding properties of insulin and insulin receptor, especially site2 interactions, because it could contribute to improved design of new insulin analogues. In this work, we used the very recent breakthroughs in the structural biology of insulin receptor to study the interactions by computational chemistry methods. It was thus possible to assess the noncovalent interactions and...

Die Mitglieder der Insulinrezeptorfamilie spielen eine wichtige Rolle in der Funktion von Zellen. Die Hauptangriffspunkte liegen hierbei im Bereich der Glucosehomöostase, sowie weiterhin bei der Proteinbiosynthese, dem Fettstoffwechsel, Elektrolyttransport, Zellwachstum, Differenzierung und Apoptose. Die beiden Hauptvertreter der Insulinrezeptorfamilie, Insulinrezeptor (InsR) und Insulin-like Growth Factor 1 Rezeptor (IGF1R) sind am besten untersucht und viele ihrer Funktionen aufgeklärt. Ein weiteres Mitglied der Familie stellt hier noch eine Ausnahme dar, der Insulin receptor-related receptor (IRR). Obwohl er hohe Sequenzhomologien zum InsR und IGF1R aufweist und in Untersuchungen gezeigt werden konnte, dass er die Möglichkeit besitzt wichtige Punkte der Insulinsignalkaskade zu aktivieren, bleibt seine Funktion unverstanden. Auch ein Ligand wurde bisher nicht identifiziert. Untersuchungen an aktivierbaren IRR-Rezeptorkonstrukten zeigten einen möglichen Einfluss auf Differenzierung, Proliferation und Apoptose von Zellen. Der IRR wird gewebespezifisch exprimiert und v.a. in neuronalen Zellen und β-Zellen des Pankreas nachgewiesen. In der vorliegenden Doktorarbeit wurde der mögliche Einfluss eines stimulierbaren IRR-Rezeptorkonstruktes auf die Proliferation und Apoptose von β-Zellen untersucht. Weiterhin wurde ermittelt, in wie fern dabei zwei Hauptsignalwege der Insulinrezeptorkaskade, der AKT/PKB und der MAPK/ERK Signalweg, aktiviert werden. Hierzu wurde ein bereits beschriebenes Colony stimulating factor 1 receptor/Insulin receptor-related receptor- (CSF1R/IRR-) Konstrukt (Dandekar et al.1998) in INS-1E Zellen überexprimiert und anschließend mit Macrophage colony stimulating factor (MCSF), dem Liganden des CSF1R, stimuliert. Dieses CSF1R/IRR-Konstrukt besteht aus dem extrazellulären Teil des CSF1R, der Transmembrandomäne des InsR und dem intrazellulären Teil des IRR. Es zeigte sich, dass das Konstrukt zu einer transienten Aktivierung des ERK-Signalweges fähig ist, ein Einfluss auf den AKT-Weg allerdings ausblieb. Ferner konnte kein Einfluss auf Proliferation oder Apoptose gezeigt werden. Dies lässt vermuten, dass die mögliche Funktion über alternative Wege verwirklicht wird, wie z.Bsp. eine Hybridrezeptorbildung zwischen IRR und IGF1R. Die angefertigte Arbeit liefert somit einen weiteren Beitrag zum Verständnis der Rolle des IRR in der Zelle.:Bibliographische Beschreibung I. Abkürzungen i 1. Einleitung 1 1.1. Beschreibung von Rezeptor Tyrosin Kinasen 1 1.2. Die Insulinsignalkaskade 2 1.2.1. Der Rezeptor und die Insulinrezeptorsubstrate 3 1.2.2. Die Phosphatidylinositol-3-Kinase (PI3K) 3 1.2.3. Die Proteinkinase B/AKT 4 1.2.4. Der MAPK/ERK Signalweg 5 1.3. Der Insulin-receptor related receptor 6 1.3.1. Vorkommen 7 1.3.2. Mögliche Funktionen 8 2. Das Promotionsprojekt 10 2.1. Hintergrund und Fragestellung 10 2.2. Methoden 11 2.3. Ergebnisse 12 3. Publikation – Druckversion 15 4. Zusammenfassung und Diskussion 25 5. Literatur 28 II. Erklärung über die Eigenständigkeit der Arbeit iv III. Lebenslauf v IV. Danksagung vi

In the late 90’s, emerging evidence revealed that the brain is insulin-sensitive, highlighted by broad expression of brain-specific insulin receptors and reports of circulating brain insulin. Contemporary literature robustly supports the role of insulin signaling in normal brain function and suggests that insulin-related processes diminish with aging, evidenced by decreased signaling markers, reduced insulin receptor density, and lower levels of insulin transport across the blood-brain barrier. In the context of pathological cognitive decline, clinical trials using intranasal insulin delivery have reported positive outcomes on memory and learning in patients with mild cognitive decline or early-stage Alzheimer’s disease. However, while the importance of insulin and its related actions in the brain are robustly supported, the distinct mechanisms and pathways that mediate these effects remain unclear. To address this, I conducted a series of experiments exploring the impact of insulin on memory and learning in two models: primary hippocampal cell cultures and the Fisher 344 animal model of aging. These studies attempted to identify relationships between insulin receptor signaling, neuronal gene expression, glucose metabolism, and calcium homeostasis in the hippocampus using either expression of a constitutively active human insulin receptor or administration of intranasal insulin. The following dissertation summarizes this work and provides valuable insights into the potential pathways mediating these relationships. Of note, intranasal studies reported that insulin is able to significantly alter gene expression patterns in the hippocampus of both young and aged rats following chronic, repeated exposure to the ligand. In cell culture, constitutive insulin signaling correlated with significantly elevated neuronal glucose uptake and utilization, as well as with significant alterations in the overall expression and localization of the neuron-specific glucose transporter 3. Interestingly, continued activity of the insulin receptor did not appear to alter voltage-gated calcium channels in hippocampal neurons despite prior evidence of the ligand’s role in other calcium-related processes. The results reported in this manuscript suggest that in the brain, insulin may be involved in a myriad of complex and dynamic events dependent on numerous variables, such as age, length of the exposure, and/or the insulin formulation used. Nevertheless, this work highlights the validity of using insulin to ameliorate age-related cognitive decline and supports the need for further studies exploring alternative approaches to enhance insulin receptor signaling in the brain.

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