Expression of islet-specific microRNAs during human pancreatic development.

During pancreatic islet development, sequential changes in gene expression are known to be necessary for efficient differentiation and function of the endocrine pancreas. Several studies till now have demonstrated that microRNAs (miRNAs), which regulate translation of gene transcripts, influence gene expression cascades involved in pancreas development. Some of these miRNAs; miR-7 and miR-375 have been known to be expressed at high levels in pancreas and are also known to be involved in Zebrafish pancreas development as well as insulin secretion in mice. We demonstrate here that 4 different islet-specific microRNAs (miR-7, miR-9, miR-375 and miR-376) are expressed at high levels during human pancreatic islet development. Of these, miR-375, is seen to be differentially expressed in human islet beta- as well as non-beta-cells. Though no significant difference in abundance of miR-375 was noted in either cell type, analysis of islet-specific miRNA and mRNA in single cells show that non-beta cells contain higher levels of miR-375. Our data demonstrate that miRNAs that are known to be regulated during Zebrafish pancreatic development may play similar role in human pancreatic islet development.