Long non-coding RNAs in Islet Cell Biology

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A large number of research efforts are currently underway to understand and prevent diabetes. Towards this goal, studies in mice have significantly advanced our understanding of the conserved signaling pathways and regulatory factors required for the development and maintenance of functional β cells. However, it is evident from the current challenges associated with predicting and treating diabetes, and generating alternative sources of endocrine cells, that we are still missing key molecular components that are required to generate, mature and preserve fully functional β cells. Recently, advances in genome biology have revealed that a large part of the mammalian genome is transcribed and includes a large number of long non-coding RNAs (lncRNAs), many which are conserved between mouse and human. LncRNAs are a diverse group of transcripts longer than 200 nucleotides that resemble mRNAs, but do not encode proteins. There is emerging evidence to suggest lncRNAs may be involved in β cell function and diabetes. In support of this data, it has been determined that the majority of diabetes-associated SNPs map to non-coding regions of the genome, many that are specifically located in lncRNAs. Therefore, the identification and characterization of conserved islet-specific lncRNAs will significantly further our understanding of the regulatory networks that control β cell development and function, and how disruption of these mechanisms may lead to diabetes. For this study, we have used comparative gene expression analyses and novel computational algorithms to identify and rank potentially relevant lncRNAs expressed in the human and mouse pancreas. We have selected two of these lncRNAs for further functional analysis based on a defined set of criteria, including their stage and level of expression, islet specificity, synteny and conservation between mouse and human, proximity to pancreas-related coding genes, and proximity to SNPs associated with diabetes. The overall goal of this proposal is to reveal the functional roles of selected lncRNAs in islet and β cell biology. We hypothesize that long non-coding RNAs (lncRNAs) represent a missing component of the islet transcriptional regulatory pathways and play essential roles in β cell development and function. To test this hypothesis, we will characterize the function and molecular activity of βlinc1, a novel lncRNA expressed in mouse and human islets. We have generated mice that are deleted for βlinc1 and will characterize the βlinc1 KO phenotype and determine the molecular activity of βlinc1. We have also identified Paupar as a conserved lncRNA that is highly expressed in adult glucagon-expressing α cells. In addition, Paupar regulates Pax6 expression and a number of Pax6-independent and dependent transcriptional activities. We have generated a null allele of Paupar by inserting an H2B-GFP cassette into the Paupar locus. We propose to characterize the expression, functional role and molecular mechanism of Paupar in the pancreatic islet.