The goal of this experiment is to identify genes differentially expressed in FACS-sorted Alpha and Beta cells.

Determine the mRNA transcriptome of human alpha and beta cells. In combination with studies 3446 and 3687, identify the cell type-specific distribution of transcription factors, signaling ligands and their receptors.

Islet samples from human donors were enzymatically dispersed to single cells and labeled with cell type-specific surface-reactive antibodies. A pan-islet antibody HPi2 was used in combination with an alpha-selective antibody, HPa1 for live isolation by FACS. Gene expression analyses were performed using the Agilent Whole Human Genome Microarray 4x44K microarray. qRT-PCR was used to validate cell type purity and expression of selected genes. Computational tools including the Human Plasma Membrane Receptome database and the Human Protein Reference Database were used to evaluate receptor-ligand representation in these populations.

Combined analysis of the transcriptomes of alpha, beta, large duct, small duct, and acinar cells revealed previously unrecognized gene expression patterns in these cell types, including HOPX (pan-islet), HDAC9 (beta cell), CDX2 (duct) and BATF2 (acinar). Furthermore, the expression of some regulatory proteins was different from that reported in mouse tissue; MAFB, for example, was expressed at equal levels in adult human alpha and beta cells but is absent from adult mouse beta cells. IRX-2 was found in adult alpha cells whereas in prior work it had been confined to fetal tissue. Analysis of ligand-receptor interactions suggested that Eph-ephrin communication between exocrine and endocrine cells as a contributor to pancreatic function.

This study in combination with studies 3687 and 3446 provides the first detailed analysis of the transcriptomes of human endocrine and exocrine cell types. These results provide insight into paracrine signaling in the pancreas and should help to guide efforts to specify human beta cell fate by ES/iPS differentiation or in situ reprogramming.

• comparison of endocrine and/or exocrine cell populations: 3446, 3687, 3834, 4114, 4135, 4395,