Pancreatic-Derived Factor (FAM3B), a Novel Islet Cytokine, Induces Apoptosis of Insulin-Secreting β-Cells

Pancreatic-Derived Factor (FAM3B), a Novel Islet Cytokine, Induces Apoptosis of Insulin-Secreting β-Cells Xiaopei Cao 1 , Zhiyong Gao 1 , Claudia E. Robert 1 , Scott Greene 1 , Gang Xu 1 , Weizhen Xu 2 , Ewan Bell 1 , Don Campbell 2 , Yuan Zhu 3 , Robert Young 1 , Matteo Trucco 1 , James F. Markmann 4 , Ali Naji 4 and Bryan A. Wolf 1 1 Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia and University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 2 Department of Pediatrics, Children’s Hospital of Philadelphia and University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania 3 Expression Genomics, GlaxoSmithKline, King of Prussia, Pennsylvania 4 Department of Surgery, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania Address correspondence and reprint requests to Dr. Bryan A. Wolf, Department of Pathology and Laboratory Medicine, Children’s Hospital of Philadelphia, 5135 Main, 34th Street and Civic Center Boulevard, Philadelphia, PA 19104-4399. E-mail: wolfb{at}mail.med.upenn.edu Abstract PANDER (PANcreatic DERived factor, FAM3B), a newly discovered secreted cytokine, is specifically expressed at high levels in the islets of Langerhans of the endocrine pancreas. To evaluate the role of PANDER in β-cell function, we investigated the effects of PANDER on rat, mouse, and human pancreatic islets; the β-TC3 cell line; and the α-TC cell line. PANDER protein was present in α- and β-cells of pancreatic islets, insulin-secreting β-TC3 cells, and glucagon-secreting α-TC cells. PANDER induced islet cell death in rat and human islets. Culture of β-TC3 cells with recombinant PANDER had a dose-dependent inhibitory effect on cell viability. This effect was also time-dependent. PANDER caused apoptosis of β-cells as assessed by electron microscopy, annexin V fluorescent staining, and flow-cytometric terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay. PANDER did not affect cytosolic Ca 2+ levels or nitric oxide levels. However, PANDER activated caspase-3. Hence, PANDER may have a role in the process of pancreatic β-cell apoptosis. DMEM, Dulbecco’s modified Eagle’s medium FBS, fetal bovine serum FITC, fluorescein isothiocyanate [Ca2+]i, intracellular Ca2+ concentration MTT, C,N-diphenyl-N′4–5-dimethyl thiazol-2-yl tetrazolium bromide NO, nitric oxide PI, propidium iodide PS, phosphatidylserine TUNEL, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeli