Is a β cell a β cell

Purpose of review This report examines recent publications identifying phenotypic and functional heterogeneity among pancreatic beta cells and investigating their potential roles in normal and abnormal islet function. The development of new methods and tools for the study of individual islet cells has produced a surge of interest in this topic. Recent findings Studies of beta cell maturation and pregnancy-induced proliferation have identified changes in serotonin and transcription factors SIX2/3 expression as markers of temporal heterogeneity. Structural and functional heterogeneity in the form of functionally distinct 'hub' and 'follower' beta cells was found in mouse islets. Heterogeneous expression of Fltp ( in mouse beta cells) and ST8SIA1 and CD9 ( in human beta cells) were associated with distinct functional potential. Several impressive reports describing the transcriptomes of individual beta cells were also published in recent months. Some of these reveal previously unknown beta cell subpopulations. Summary A wealth of information on functional and phenotypic heterogeneity has been collected recently, including the transcriptomes of individual beta cells and the identities of functionally distinct beta cell subpopulations. Several studies suggest the existence of two broad categories: a more proliferative but less functional and a less proliferative but more functional beta cell type. The identification of functionally distinct subpopulations and their association with type 2 diabetes underlines the potential clinical importance of these investigations.