@article {775, title = {microRNAs-mediated regulation of insulin signaling in white adipose tissue during aging: Role of caloric restriction.}, journal = {Aging Cell}, year = {2023}, month = {2023 Jul 04}, pages = {e13919}, abstract = {

Caloric restriction is a non-pharmacological intervention known to ameliorate the metabolic defects associated with aging, including insulin resistance. The levels of miRNA expression may represent a predictive tool for aging-related alterations. In order to investigate the role of miRNAs underlying insulin resistance in adipose tissue during the early stages of aging, 3- and 12-month-old male animals fed ad libitum, and 12-month-old male animals fed with a 20\% caloric restricted diet were used. In this work we demonstrate that specific miRNAs may contribute to the impaired insulin-stimulated glucose metabolism specifically in the subcutaneous white adipose tissue, through the regulation of target genes implicated in the insulin signaling cascade. Moreover, the expression of these miRNAs is modified by caloric restriction in middle-aged animals, in accordance with the improvement of the metabolic state. Overall, our work demonstrates that alterations in posttranscriptional gene expression because of miRNAs dysregulation might represent an endogenous mechanism by which insulin response in the subcutaneous fat depot is already affected at middle age. Importantly, caloric restriction could prevent this modulation, demonstrating that certain miRNAs could constitute potential biomarkers of age-related metabolic alterations.

}, issn = {1474-9726}, doi = {10.1111/acel.13919}, author = {Corrales, Patricia and Martin-Taboada, Marina and Vivas-Garc{\'\i}a, Yurena and Torres, Lucia and Ramirez-Jimenez, Laura and Lopez, Yamila and Horrillo, Daniel and Vila-Bedmar, Rocio and Barber-Cano, Eloisa and Izquierdo-Lahuerta, Adriana and Pe{\~n}a-Chilet, Maria and Mart{\'\i}nez, Carmen and Dopazo, Joaquin and Ros, Manuel and Medina-Gomez, Gema} } @article {531, title = {Early peroxisome proliferator-activated receptor gamma regulated genes involved in expansion of pancreatic beta cell mass.}, journal = {BMC Med Genomics}, volume = {4}, year = {2011}, month = {2011 Dec 30}, pages = {86}, abstract = {

BACKGROUND: The progression towards type 2 diabetes depends on the allostatic response of pancreatic beta cells to synthesise and secrete enough insulin to compensate for insulin resistance. The endocrine pancreas is a plastic tissue able to expand or regress in response to the requirements imposed by physiological and pathophysiological states associated to insulin resistance such as pregnancy, obesity or ageing, but the mechanisms mediating beta cell mass expansion in these scenarios are not well defined. We have recently shown that ob/ob mice with genetic ablation of PPARγ2, a mouse model known as the POKO mouse failed to expand its beta cell mass. This phenotype contrasted with the appropriate expansion of the beta cell mass observed in their obese littermate ob/ob mice. Thus, comparison of these models islets particularly at early ages could provide some new insights on early PPARγ dependent transcriptional responses involved in the process of beta cell mass expansion

RESULTS: Here we have investigated PPARγ dependent transcriptional responses occurring during the early stages of beta cell adaptation to insulin resistance in wild type, ob/ob, PPARγ2 KO and POKO mice. We have identified genes known to regulate both the rate of proliferation and the survival signals of beta cells. Moreover we have also identified new pathways induced in ob/ob islets that remained unchanged in POKO islets, suggesting an important role for PPARγ in maintenance/activation of mechanisms essential for the continued function of the beta cell.

CONCLUSIONS: Our data suggest that the expansion of beta cell mass observed in ob/ob islets is associated with the activation of an immune response that fails to occur in POKO islets. We have also indentified other PPARγ dependent differentially regulated pathways including cholesterol biosynthesis, apoptosis through TGF-β signaling and decreased oxidative phosphorylation.

}, keywords = {Animals, Cell Proliferation, Cell Survival, Cholesterol, Down-Regulation, Female, Gene Expression Regulation, Gene Knockout Techniques, Insulin Resistance, Insulin-Secreting Cells, Mice, obesity, Oxidation-Reduction, Phosphorylation, PPAR gamma, Signal Transduction, Transcription, Genetic, Transforming Growth Factor beta}, issn = {1755-8794}, doi = {10.1186/1755-8794-4-86}, author = {Vivas, Yurena and Martinez-Garcia, Cristina and Izquierdo, Adriana and Garcia-Garcia, Francisco and Callejas, Sergio and Velasco, Ismael and Campbell, Mark and Ros, Manuel and Dopazo, Ana and Dopazo, Joaquin and Vidal-Puig, Antonio and Medina-Gomez, Gema} }