The highly sophisticated identity of pancreatic β-cells is geared to accomplish its unique feat of providing insulin for organismal glucose and lipid homeostasis. This requires a particular and streamlined fuel metabolism which defines mature β-cells as glucose sensors linked to an insulin exocytosis machinery. The establishment of an appropriate β-cell mass and function during development as well as the maintenance of their identity throughout life are necessary for energy homeostasis. The small non-coding RNAs, microRNAs (miRNAs), are now wellrecognized regulators of gene transcripts, which in general are negatively affected by them.Convincing evidence exists to view miRNAs as major actors in β-cell development and function, suggesting an important role for them in the distinctive β-cell 'identity card'. Here, we summarize key features that associate miRNAs and the establishment of the appropriate β-cell identity and its necessary maintenance during their 'long life'.
K E Y W O R D Sβ-cell development, β-cell identity, insulin secretion, microRNAs, type 2 diabetes
| INTRODUCTIONThe identity of cells is defined by the expression of a particular set of genes and the resulting production of specific proteins and constituents depending on them. These expression patterns follow a complex scenario during cell development, where timing and quantity of the proteins produced are essential and finely regulated. The maintenance of these distinctive cell identities throughout life is required for normal physiology and health of the organism.In mammals, β-cells are the major cell type within the pancreatic islets. In humans, they represent nearly 60% of the islet cells.1 They are the unique source of circulating insulin, the chief anabolic hormone. Indeed, insulin is critically important for fuel homeostasis and energy storage. Concerning glucose homeostasis, β-cells serve as a glucostat in a highly sophisticated homeostatic feedback system.