LncRNA ARGI Contributes to Virus-Induced Pancreatic ß Cell Inflammation Through Transcriptional Activation of IFN-Stimulated Genes.

Type 1 diabetes (T1D) is a complex autoimmune disease that develops in genetically susceptible individuals. Most T1D-associated single nucleotide polymorphisms (SNPs) are located in non-coding regions of the human genome. Interestingly, SNPs in long non-coding RNAs (lncRNAs) may result in the disruption of their secondary structure, affecting their function, and in turn, the expression of potentially pathogenic pathways. In the present work, the function of a virus-induced T1D-associated lncRNA named ARGI (Antiviral Response Gene Inducer) is characterized. Upon a viral insult, ARGI is upregulated in the nuclei of pancreatic ß cells and binds to CTCF to interact with the promoter and enhancer regions of IFNß and interferon-stimulated genes, promoting their transcriptional activation in an allele-specific manner. The presence of the T1D risk allele in ARGI induces a change in its secondary structure. Interestingly, the T1D risk genotype induces hyperactivation of type I IFN response in pancreatic ß cells, an expression signature that is present in the pancreas of T1D patients. These data shed light on the molecular mechanisms by which T1D-related SNPs in lncRNAs influence pathogenesis at the pancreatic ß cell level and opens the door for the development of therapeutic strategies based on lncRNA modulation to delay or avoid pancreatic ß cell inflammation in T1D.

Molecular mechanisms of ß-cell dysfunction and death in monogenic forms of diabetes.

Monogenetic forms of diabetes represent 1%-5% of all diabetes cases and are caused by mutations in a single gene. These mutations, that affect genes involved in pancreatic ß-cell development, function and survival, or insulin regulation, may be dominant or recessive, inherited or de novo. Most patients with monogenic diabetes are very commonly misdiagnosed as having type 1 or type 2 diabetes. The severity of their symptoms depends on the nature of the mutation, the function of the affected gene and, in some cases, the influence of additional genetic or environmental factors that modulate severity and penetrance. In some patients, diabetes is accompanied by other syndromic features such as deafness, blindness, microcephaly, liver and intestinal defects, among others. The age of diabetes onset may also vary from neonatal until early adulthood manifestations. Since the different mutations result in diverse clinical presentations, patients usually need different treatments that range from just diet and exercise, to the requirement of exogenous insulin or other hypoglycemic drugs, e.g., sulfonylureas or glucagon-like peptide 1 analogs to control their glycemia. As a consequence, awareness and correct diagnosis are crucial for the proper management and treatment of monogenic diabetes patients. In this chapter, we describe mutations causing different monogenic forms of diabetes associated with inadequate pancreas development or impaired ß-cell function and survival, and discuss the molecular mechanisms involved in ß-cell demise.

tRNA Biology in the Pathogenesis of Diabetes: Role of Genetic and Environmental Factors.

The global rise in type 2 diabetes results from a combination of genetic predisposition with environmental assaults that negatively affect insulin action in peripheral tissues and impair pancreatic ß-cell function and survival. Nongenetic heritability of metabolic traits may be an important contributor to the diabetes epidemic. Transfer RNAs (tRNAs) are noncoding RNA molecules that play a crucial role in protein synthesis. tRNAs also have noncanonical functions through which they control a variety of biological processes. Genetic and environmental effects on tRNAs have emerged as novel contributors to the pathogenesis of diabetes. Indeed, altered tRNA aminoacylation, modification, and fragmentation are associated with ß-cell failure, obesity, and insulin resistance. Moreover, diet-induced tRNA fragments have been linked with intergenerational inheritance of metabolic traits. Here, we provide a comprehensive review of how perturbations in tRNA biology play a role in the pathogenesis of monogenic and type 2 diabetes.

Expression of zebrafish cpsf6 in embryogenesis and role of protein domains on subcellular localization.

CPSF6 is a component of the CFIm complex, involved in mRNA 3'end processing. Despite increasing interest on this protein as a consequence of proposed roles in cancer and HIV infection, several aspects of CPSF6 biological function are poorly understood. In this work we studied the expression of the zebrafish ortholog cpsf6 in early stages of embryo development. Quantitative RT-PCR studies showed that zebrafish cpsf6 mRNA is maternally inherited and that its concentration markedly decreases during early development. We found a generalized distribution of cpsf6 mRNA in early stages through whole mount hybridization experiments. By performing Western blot, we also found a decrease in zebrafish Cpsf6 levels during development. Our analysis of the subcellular localization of this protein using a heterologous system showed a distinct pattern characterized by the presence of nuclear foci. We also studied the relevance of different protein domains on subcellular localization, showing that the C-terminal domain is critical for nuclear localization. Collectively, our results showed that cpsf6 expression changes during early development and that the subcellular localization of the protein is similar to that of the human ortholog.