Identificación de nuevas vías de señalización de la ciclinaD3 implicadas en la viabilidad y funcionalidad de la célula beta pancreática en la diabetes autoinmune

La diabetis tipus 1 és una malaltia autoimmune caracteritzada per la destrucció de les cèl·lules beta productores d'insulina en els illots pancreàtics per l'activació de limfòcits autorreactivos. Estudis previs del nostre laboratori van demostrar que la infiltració leucocitària dels illots causa una disminució significativa de l'expressió tant de ciclinaD3 com de Cdk11 en el model murí NOD (Non Obese Diabetic), evidenciant un possible paper d'aquestes proteïnes en la diabetis autoimmune. Per això, els objectius d'aquest projecte han estat trobar vies de senyalització que impliquin la ciclinaD3 en la viabilitat i supervivència de les cèl·lules beta i estudiar la funció de la Cdk11 en la precipitació de la diabetis autoimmune. Com a resultat, observem que la ciclinaD3 interacciona amb proteïnes independents de cicle cel·lular implicades en processos fisiològics com la resposta UPR i el trànsit vesicular, i que la hemideficiencia de Cdk11 protegeix a les cèl·lules beta de l'apoptosi. Es pot concloure que ciclinaD3 i Cdk11 duen a terme papers antagònics, i tots dos desenvolupen una funció independent de cicle cel·lular en la viabilitat de les cèl·lules beta. Aquests descobriments ofereixen noves perspectives pel que fa a Cdk11 i ciclinaD3 com a potencials noves dianes d'intervenció en la diabetis autoimmune.La diabetes tipo 1 es una enfermedad autoinmune caracterizada por la destrucción de las células beta productoras de insulina en los islotes pancreáticos por la activación de linfocitos autorreactivos. Estudios previos de nuestro laboratorio demostraron que la infiltración leucocitaria de los islotes causa una disminución significativa de la expresión tanto de ciclinaD3 como de Cdk11 en el modelo murino NOD (Non Obese Diabetic), evidenciando un posible papel de estas proteínas en la diabetes autoinmune. Por ello, los objetivos de este proyecto han sido hallar vías de señalización que impliquen a la ciclinaD3 en la viabilidad y supervivencia de las células beta y estudiar la función de la Cdk11 en la precipitación de la diabetes autoinmune. Como resultado, observamos que la ciclinaD3 interacciona con proteínas independientes de ciclo celular implicadas en procesos fisiológicos como la respuesta UPR y el tráfico vesicular, y que la hemideficiencia de Cdk11 protege a las células beta de la apoptosis. Se puede concluir que ciclinaD3 y Cdk11 llevan a cabo papeles antagónicos, y ambos desarrollan una función independiente de ciclo celular en la viabilidad de las células beta. Estos descubrimientos ofrecen nuevas perspectivas con respecto a Cdk11 y ciclinaD3 como potenciales nuevas dianas de intervención en la diabetes autoinmune.Type 1 diabetes is an autoimmune disease characterized by the destruction of insulin-producing beta cells in the pancreatic islets by the activation of autoreactive lymphocytes. Previous studies in our laboratory showed that leukocyte infiltration of the islets causes a significant decrease in the expression of both cyclinD3 and Cdk11 in the NOD (Non Obese Diabetic) murine model, evidencing a possible role of these proteins in autoimmune diabetes. For this reason, the objectives of this project have been to find signaling pathways that involve cyclinD3 in the viability and survival of beta cells and to study the role of Cdk11 in the precipitation of autoimmune diabetes. As a result, we observed that cyclin D3 interacts with cell cycle independent proteins involved in physiological processes such as the UPR response and vesicular trafficking, and that Cdk11 hemideficiency protects beta cells from apoptosis. It can be concluded that cyclinD3 and Cdk11 perform antagonistic roles, and both play a cell cycle independent function in beta cell viability. These discoveries offer new insights regarding Cdk11 and cyclinD3 as potential new intervention targets in autoimmune diabetes

Impaired PLP-dependent metabolism in brain samples from Huntington disease patients and transgenic R6/1 mice

Oxidative stress has been described as important to Huntington disease (HD) progression. In a previous HD study, we identified several carbonylated proteins, including pyridoxal kinase and antiquitin, both of which are involved in the metabolism of pyridoxal 5´-phosphate (PLP), the active form of vitamin B6. In the present study, pyridoxal kinase levels were quantified and showed to be decreased both in HD patients and a R6/1 mouse model, compared to control samples. A metabolomic analysis was used to analyze metabolites in brain samples of HD patients and R6/1 mice, compared to control samples using mass spectrometry. This technique allowed detection of increased concentrations of pyridoxal, the substrate of pyridoxal kinase. In addition, PLP, the product of the reaction, was decreased in striatum from R6/1 mice. Furthermore, glutamate and cystathionine, both substrates of PLP-dependent enzymes were increased in HD. This reinforces the hypothesis that PLP synthesis is impaired, and could explain some alterations observed in the disease. Together, these results identify PLP as a potential therapeutic agent

CDK11 Promotes Cytokine-Induced Apoptosis in Pancreatic Beta Cells Independently of Glucose Concentration and Is Regulated by Inflammation in the NOD Mouse Model

Background: Pancreatic islets are exposed to strong pro-apoptotic stimuli: inflammation and hyperglycemia, during the progression of the autoimmune diabetes (T1D). We found that the Cdk11(Cyclin Dependent Kinase 11) is downregulated by inflammation in the T1D prone NOD (non-obese diabetic) mouse model. The aim of this study is to determine the role of CDK11 in the pathogenesis of T1D and to assess the hierarchical relationship between CDK11 and Cyclin D3 in beta cell viability, since Cyclin D3, a natural ligand for CDK11, promotes beta cell viability and fitness in front of glucose. Methods: We studied T1D pathogenesis in NOD mice hemideficient for CDK11 (N-HTZ), and, in N-HTZ deficient for Cyclin D3 (K11HTZ-D3KO), in comparison to their respective controls (N-WT and K11WT-D3KO). Moreover, we exposed pancreatic islets to either pro-inflammatory cytokines in the presence of increasing glucose concentrations, or Thapsigargin, an Endoplasmic Reticulum (ER)-stress inducing agent, and assessed apoptotic events. The expression of key ER-stress markers (Chop, Atf4 and Bip) was also determined. Results: N-HTZ mice were significantly protected against T1D, and NS-HTZ pancreatic islets exhibited an impaired sensitivity to cytokine-induced apoptosis, regardless of glucose concentration. However, thapsigargin-induced apoptosis was not altered. Furthermore, CDK11 hemideficiency did not attenuate the exacerbation of T1D caused by Cyclin D3 deficiency. Conclusions: This study is the first to report that CDK11 is repressed in T1D as a protection mechanism against inflammation-induced apoptosis and suggests that CDK11 lies upstream Cyclin D3 signaling. We unveil the CDK11/Cyclin D3 tandem as a new potential intervention target in T1D

Impaired PLP-dependent metabolism in brain samples from Huntington disease patients and transgenic R6/1 mice

Oxidative stress has been described as important to Huntington disease (HD) progression. In a previous HD study, we identified several carbonylated proteins, including pyridoxal kinase and antiquitin, both of which are involved in the metabolism of pyridoxal 5´-phosphate (PLP), the active form of vitamin B6. In the present study, pyridoxal kinase levels were quantified and showed to be decreased both in HD patients and a R6/1 mouse model, compared to control samples. A metabolomic analysis was used to analyze metabolites in brain samples of HD patients and R6/1 mice, compared to control samples using mass spectrometry. This technique allowed detection of increased concentrations of pyridoxal, the substrate of pyridoxal kinase. In addition, PLP, the product of the reaction, was decreased in striatum from R6/1 mice. Furthermore, glutamate and cystathionine, both substrates of PLP-dependent enzymes were increased in HD. This reinforces the hypothesis that PLP synthesis is impaired, and could explain some alterations observed in the disease. Together, these results identify PLP as a potential therapeutic agent

Impaired PLP-dependent metabolism in brain samples from Huntington disease patients and transgenic R6/1 mice

Oxidative stress has been described as important to Huntington disease (HD) progression. In a previous HD study, we identified several carbonylated proteins, including pyridoxal kinase and antiquitin, both of which are involved in the metabolism of pyridoxal 5´-phosphate (PLP), the active form of vitamin B6. In the present study, pyridoxal kinase levels were quantified and showed to be decreased both in HD patients and a R6/1 mouse model, compared to control samples. A metabolomic analysis was used to analyze metabolites in brain samples of HD patients and R6/1 mice, compared to control samples using mass spectrometry. This technique allowed detection of increased concentrations of pyridoxal, the substrate of pyridoxal kinase. In addition, PLP, the product of the reaction, was decreased in striatum from R6/1 mice. Furthermore, glutamate and cystathionine, both substrates of PLP-dependent enzymes were increased in HD. This reinforces the hypothesis that PLP synthesis is impaired, and could explain some alterations observed in the disease. Together, these results identify PLP as a potential therapeutic agent