Indiana University-Purdue University Indianapolis (IUPUI) / Patients with the genetic disorder tuberous sclerosis complex (TSC) suffer from neoplastic growths in multiple organ systems. These growths are the result of inactivating mutations in either the TSC1 or TSC2 tumor suppressor genes, which negatively regulate the activity of mammalian target of rapamycin complex 1(mTORC1). There is currently no cure for this disease; however, my research has found that cells harboring TSC2-inactivating mutations derived from a rat model of TSC are sensitive to apoptosis induced by the clinically approved proteasome inhibitor, bortezomib, in a manner dependent on their high levels of mTORC1 activation. We see that bortezomib induces the unfolded protein response (UPR) in our cell model of TSC, resulting in cell death via apoptosis. The UPR is induced by accumulation of unfolded protein in the endoplasmic reticulum (ER) which activates the three branches of this pathway: Activating transcription factor 6 (ATF6) cleavage, phosphorylation of eukaryotic initiation factor 2α (eIF2α), and the splicing of X-box binding protein1 (XBP1) mRNA. Phosphorylation of eIF2α leads to global inhibition of protein synthesis, preventing more unfolded protein from accumulating in the ER. This phosphorylation also induces the transcription and translation of ATF4 and CCAAT-enhancer binding protein homologous protein (CHOP). Blocking mTORC1 activity in these cells using the mTORC1 inhibitor, rapamycin, prevented the expression of ATF4 and CHOP at both the mRNA and protein level during bortezomib treatment. Rapamycin treatment also reduced apoptosis induced by bortezomib; however, it did not affect bortezomib-induced eIF2α phosphorylation or ATF6 cleavage. These data indicate that rapamycin can repress the induction of UPR-dependent apoptosis by suppressing the transcription of ATF4 and CHOP mRNAs. In addition to these findings, we find that a TSC2-null angiomyolipoma cell line forms vacuoles when treated with the proteasome inhibitor MG-132. We found these vacuoles to be derived from the ER and that rapamycin blocked their formation. Rapamycin also enhanced expansion of the ER during MG-132 stress and restored its degradation by autophagy. Taken together these findings suggest that bortezomib might be used to treat neoplastic growths associated with TSC. However, they also caution against combining specific cell death inducing agents with rapamycin during chemotherapy.

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Indiana University-Purdue University Indianapolis (IUPUI) / Sequestration at the aggresome and degradation through autophagy are two approaches by which a cell can counteract the toxic effect of misfolded proteins. Tuberous sclerosis (TS) and cancer cells can become dependent on autophagy for survival due to the high demand for protein synthesis, thus making protein clearance a potential therapeutic target. Because of its histone deacetylase (HDAC) inhibitory activity, we hypothesized that 4-phenylbutyrate (4-PBA) inhibits HDAC6 and aggresome formation to induce TS cell death. We found that 4-PBA treatment increases cell death and reduces bortezomib-induced aggresome formation. To link these results with HDAC inhibition we used two other HDAC inhibitors, trichostatin A (TSA) and tubastatin, and found that they also reduce bortezomib-induced protein aggregation. Because tubulin is a target of HDAC6, we next measured the effect of the HDAC inhibitors and 4-PBA treatment on tubulin acetylation. As expected, tubastatin increased tubulin acetylation but surprisingly TSA and 4-PBA did not. Because 4-PBA did not significantly inhibit HDAC6, we next hypothesized that 4-PBA was alternatively inducing autophagy and increasing aggresome clearance. Surprisingly, autophagy inhibition did not prevent the 4-PBA-induced reduction in protein aggregation. In conclusion, we found 4-PBA to induce cell death and reduce aggresome levels in TS cells, but we found no link between these phenomena. We next hypothesized that loss of the Ral guanine nucleotide exchange factor Rgl2 induces cell death via autophagy inhibition in pancreatic adenocarcinoma (PDAC) cells. KRas is mutationally activated in over 90% of PDACs and directly activates Rgl2. Rgl2 activates RalB, a known regulator of autophagy, and Rgl2 has been shown to promote PDAC cell survival. We first confirmed that loss of Rgl2 does increase cell death in PDAC cells. Initial experiments using doubly tagged fluorescent p62 and LC3 (autophagy markers) suggested that loss of Rgl2 inhibited autophagosome accumulation, but after developing a more sophisticated quantitation method we found loss of Rgl2 to have no effect. We also measured endogenous LC3 levels, and these experiments confirmed loss of Rgl2 to have no effect on autophagy levels. Therefore, loss of Rgl2 increases cell death in PDAC cells, but does not have a significant effect on autophagy.

O complexo esclerose tuberosa (CET) e as doenças renais policísticas autossômica dominante (DRPAD) e autossômica recessiva (DRPAR) são doenças monogênicas associadas a cistogênese renal. Os produtos dos genes mutados nessas enfermidades, respectivamente tuberina e hamartina para CET, policistina-1 (PC1) e policistina-2 para DRPAD, e poliductina/fibrocistina para DRPAR, modulam proliferação, diferenciação, apoptose, crescimento e/ou migração celular. Neste estudo empregamos um sistema tridimensional de cultura de células IMCD para caracterizar os perfis de expressão dessas proteínas durante a tubulogênese. Usando uma matriz de colágeno tipo I/Matrigel e fator de crescimento de hepatócito (HGF), a formação de estruturas alongadas se iniciou dois dias após o plaqueamento in vitro (2 DIV), ao passo que o desenvolvimento de lúmen ocorreu entre 10-14 DIV. A marcação para caspase-3 ativa foi mais intensa nas fases iniciais da tubulogênese, enquanto a marcação para Ki-67 foi uniformemente pronunciada em estágios mais tardios. A tuberina e a hamartina apresentaram expressão citoplasmática e co-localização acentuada em 6 e 12 DIV. A PC1 apresentou maior expressão nas porções ramificadas dos túbulos que nas não ramificadas no 12 DIV, um padrão não verificado para a PC2. Estas proteínas exibiram expressão citoplasmática, assim como expressão ocasional e pontual na membrana plasmática. PD1 também apresentou expressão citoplasmática. Nossos dados sugerem que a apoptose e a ciclagem celular sincrônica durante a tubulogênese in vitro são mais acentuadas, respectivamente, em fases mais precoces e mais tardias da formação tubular. Nossos achados demonstram, além disso, que as proteínas relacionadas ao CET e às DRPs são expressas in vitro durante a tubulogênese, apoiando um papel importante para a interação tuberina-hamartina na formação tubular, e são consistentes com o padrão de expressão diferencial da PC1 observado durante a nefrogênese / Tuberous sclerosis complex (TSC) and autosomal dominant and recessive polycystic kidney diseases (ADPKD and ARPKD) are monogenic diseases associated with renal cystogenesis. The products of the genes mutated in these disorders, respectively tuberin and hamartin for TSC, and polycystin-1 (PC1), polycystin-2 (PC2) and polyductin/fibrocystin (PD1) for PKD, modulate cell proliferation, differentiation, apoptosis, growth and/or migration. We have employed an IMCD tridimensional cell culture system to characterize their expression profiles along tubulogenesis. Using a type I collagen/Matrigel matrix and hepatocyte growth factor (HGF), the formation of elongated structures initiated 2 days after in vitro plating (2 DIV) while lumen developed between 10-14 DIV. Active caspase-3 labeling was more intense in initial phases of tubulogenesis while Ki-67 staining was uniformly pronounced in later stages. Tuberin and hamartin showed cytoplasmic expression and marked co- localization at 6 and 12 DIV. PC1 displayed higher expression in branching than non- branching portions of the tubules at 12 DIV, a pattern not verified for PC2. These proteins presented cytoplasmic and occasional, punctate membrane expression. PD1 also showed cytoplasmic expression. Our data suggest that apoptosis and synchronous cell cycling during in vitro tubulogenesis are more remarkable, respectively, in early and later steps of tubule formation. In addition, our findings demonstrate that the TSC and PKD proteins are expressed in vitro during tubulogenesis, supporting an important role for tuberin-hamartin interaction in tubular formation, and are consistent with the differential PC1 expression pattern observed during nephrogenesis

O complexo esclerose tuberosa (CET) e as doenças renais policísticas autossômica dominante (DRPAD) e autossômica recessiva (DRPAR) são doenças monogênicas associadas a cistogênese renal. Os produtos dos genes mutados nessas enfermidades, respectivamente tuberina e hamartina para CET, policistina-1 (PC1) e policistina-2 para DRPAD, e poliductina/fibrocistina para DRPAR, modulam proliferação, diferenciação, apoptose, crescimento e/ou migração celular. Neste estudo empregamos um sistema tridimensional de cultura de células IMCD para caracterizar os perfis de expressão dessas proteínas durante a tubulogênese. Usando uma matriz de colágeno tipo I/Matrigel e fator de crescimento de hepatócito (HGF), a formação de estruturas alongadas se iniciou dois dias após o plaqueamento in vitro (2 DIV), ao passo que o desenvolvimento de lúmen ocorreu entre 10-14 DIV. A marcação para caspase-3 ativa foi mais intensa nas fases iniciais da tubulogênese, enquanto a marcação para Ki-67 foi uniformemente pronunciada em estágios mais tardios. A tuberina e a hamartina apresentaram expressão citoplasmática e co-localização acentuada em 6 e 12 DIV. A PC1 apresentou maior expressão nas porções ramificadas dos túbulos que nas não ramificadas no 12 DIV, um padrão não verificado para a PC2. Estas proteínas exibiram expressão citoplasmática, assim como expressão ocasional e pontual na membrana plasmática. PD1 também apresentou expressão citoplasmática. Nossos dados sugerem que a apoptose e a ciclagem celular sincrônica durante a tubulogênese in vitro são mais acentuadas, respectivamente, em fases mais precoces e mais tardias da formação tubular. Nossos achados demonstram, além disso, que as proteínas relacionadas ao CET e às DRPs são expressas in vitro durante a tubulogênese, apoiando um papel importante para a interação tuberina-hamartina na formação tubular, e são consistentes com o padrão de expressão diferencial da PC1 observado durante a nefrogênese / Tuberous sclerosis complex (TSC) and autosomal dominant and recessive polycystic kidney diseases (ADPKD and ARPKD) are monogenic diseases associated with renal cystogenesis. The products of the genes mutated in these disorders, respectively tuberin and hamartin for TSC, and polycystin-1 (PC1), polycystin-2 (PC2) and polyductin/fibrocystin (PD1) for PKD, modulate cell proliferation, differentiation, apoptosis, growth and/or migration. We have employed an IMCD tridimensional cell culture system to characterize their expression profiles along tubulogenesis. Using a type I collagen/Matrigel matrix and hepatocyte growth factor (HGF), the formation of elongated structures initiated 2 days after in vitro plating (2 DIV) while lumen developed between 10-14 DIV. Active caspase-3 labeling was more intense in initial phases of tubulogenesis while Ki-67 staining was uniformly pronounced in later stages. Tuberin and hamartin showed cytoplasmic expression and marked co- localization at 6 and 12 DIV. PC1 displayed higher expression in branching than non- branching portions of the tubules at 12 DIV, a pattern not verified for PC2. These proteins presented cytoplasmic and occasional, punctate membrane expression. PD1 also showed cytoplasmic expression. Our data suggest that apoptosis and synchronous cell cycling during in vitro tubulogenesis are more remarkable, respectively, in early and later steps of tubule formation. In addition, our findings demonstrate that the TSC and PKD proteins are expressed in vitro during tubulogenesis, supporting an important role for tuberin-hamartin interaction in tubular formation, and are consistent with the differential PC1 expression pattern observed during nephrogenesis

Since the discovery of cell-free fetal DNA in peripheral blood of pregnant women, cell-free nucleic acids in maternal plasma are explored in relation to non-invasive prenatal diagnosis of various fetal conditions and pregnancy complications. Non-invasive prenatal diagnosis of monogenic diseases represented by TSC1-linked tuberous sclerosis could be achieved by detection of paternally-inherited mutant allele in the pool of maternal alleles in plasma. Reliability of detection of mutant allele could be improved by simultaneous mutation haplotype analysis or detection of universal fetal marker. None of the 3 methods (allele- specific real-time PCR, SNaPshot minisequencing and quantitative fluorescent PCR) evaluated using artificial mixtures and maternal plasma samples reliably and accurately detected low-frequency allele distinguished by point mutation, SNP or microsatellite in TSC1 gene or in its close proximity. We developed a strategy for prediction of proportion of informative couples for panel of SNPs of interest that can be applied to any monogenic disease. Exploiting differential methylation of promoters of genes RASSF1A, HLCS and OLIG2 in maternal and fetal genome, we failed to establish functional fetal marker. MicroRNAs of placental origin released into plasma could serve as biomarkers of...

La trisomie 21 (T21), le Syndrome X Fragile (SXF), la Sclérose tubéreuse de Bourneville (STB) et les mutations SYNGAP1 sont causés par des dysfonctionnements des voies moléculaires qui entraînent notamment un déséquilibre dans l’excitation et l’inhibition de l’activité neuronale qui aurait des impacts sur le développement et le fonctionnement du cerveau. Toutefois, il est difficile de faire le pont entre les déséquilibres moléculaires observés dans les modèles animaux et les particularités structurelles, fonctionnelles et cognitives observées dans ces syndromes chez l’humain. À notre connaissance, peu d’études ont comparé différents syndromes génétiques sur les processus sensoriels, l’apprentissage de base ou encore leurs caractéristiques comportementales en utilisant des paradigmes similaires et translationnels, permettant de mieux comprendre leurs particularités. Le premier volet de cette thèse vise à identifier si l’activité électroencéphalographique serait un biomarqueur adéquat représentant les altérations neurobiologiques tant des processus sensoriels que d’apprentissage chez les humains présentant ces syndromes. L’étude #1 avait comme objectif de décrire le traitement sensoriel auditif, comme il s’agit d’un processus élémentaire, et ce, chez les mutations SYNGAP1 qui représentent une condition génétique encore peu étudiée chez l’humain. Les résultats ont d’ailleurs permis d’identifier une diminution de la synchronisation de phase et une augmentation de la puissance dans la bande gamma qui distinguent cette condition génétique tant des participants sans DI que de la T21. Toujours dans l’esprit d’identifier des biomarqueurs électroencéphalographiques, mais cette fois au niveau d’un processus cognitif de base, l’étude #2 avait pour objectif de comparer tous ces syndromes dans un paradigme de suppression neuronale (SN) afin de vérifier la présence de SN et de comparer l’apprentissage de base chez ces populations. Les résultats ont identifiés que la T21 et le SXF présentaient tous les deux un patron de SN et que le SXF présentait relativement une plus forte habituation indiquant des particularités spécifiques selon les syndromes. Le deuxième volet, davantage clinique, permet de comparer les profils comportementaux associés au fonctionnement adaptatif entre les syndromes et à décrire les pistes d’intervention existantes. L’étude #3 a notamment mis en évidence que le QI et les symptômes de TDAH sont associés au fonctionnement adaptatif auprès de ces différents syndromes dont le SXF et la STB. Cet article a aussi permis de décrire les profils comportementaux de ces mêmes conditions en révélant davantage de difficultés rapportées chez les individus présentant un SXF, alors que la T21 présentait moins de particularités cliniques au niveau comportemental. Enfin, l’article #4 a mis en lumière diverses interventions utilisées auprès de la population présentant une DI notamment des stratégies cognitivo-comportementales et compensatoires. Cette thèse permet donc de dresser un portrait spécifique de ces syndromes génétiques concernant leur signature électrophysiologique lors du traitement sensoriel et de l’apprentissage ainsi que sur le plan des comorbidités comportementales et de leur relation avec le fonctionnement adaptatif, pour ensuite aborder les interventions actuelles en DI. Les diverses particularités identifiées à plusieurs niveaux ont permis de générer des suggestions pouvant guider certaines interventions futures. / Down syndrome (DS), Fragile X syndrome (FXS), Tuberous sclerosis complex (TSC) and SYNGAP1 mutations are caused by dysfunctions of the molecular pathways which lead among others to an imbalance in excitation and inhibition of the neuronal activity that would impact the brain development and its functioning. However, it is difficult to directly bridge the gap between the molecular imbalances observed in animal models with the structural, functional and cognitive characteristics observed in human with these syndromes. To our knowledge, few studies have compared those different genetic syndromes on sensory processing, basic learning or on their behavioural issues using similar and translational paradigms then allowing a better understanding of their specificities. The first part of this thesis aims to identify whether electroencephalographic activity would be an adequate biomarker representing neurobiological alterations both in sensory processing and learning in humans with these syndromes. The goal of study #1 was to describe auditory sensory processing, as a very first basic process, in SYNGAP1 mutations being a genetic condition still little studied in humans. Results showed a decrease in phase synchronization and an increase in the power of gamma band which distinguish this genetic condition both from participants without ID and from DS. Still in order to identify electroencephalographic biomarkers, but this time at a basic cognitive level, study #2 aimed to compare all these syndromes in a repetition suppression (RS) paradigm in order to observe the presence of RS and compare basic learning in these populations. The results identified a RS pattern in both DS and FXS. FXS also exhibited relatively higher habituation then indicating specific features according to the syndrome. The second part, addressing clinical aspects, permits to compare the behavioural profiles associated with adaptive functioning between syndromes and to describe existing interventions on ID population. Study #3 notably highlighted that IQ and ADHD symptoms are associated with adaptive functioning especially in FXS and TSC. This article also made it possible to describe the behavioural profiles of these syndromes, revealing more difficulties reported in individuals with FXS, while DS presented fewer behavioural issues. Finally, article #4 highlighted various interventions used with ID population, notably cognitive-behavioural and compensatory strategies. This thesis therefore makes it possible to gain a better understanding of these genetic syndromes concerning their electrophysiological signature during sensory processing and learning as well as in terms of behavioural comorbidities and their relationship with adaptive functioning, to then address current ID interventions. These different syndromic particularities identified at several levels made it possible to generate suggestions that could guide future interventions in this field.