Pancreatic β-Cells Express Phagocyte-Like NAD(P)H Oxidase
- Henriette R. Oliveira,
- Rozangela Verlengia,
- Carla R.O. Carvalho,
- Luiz R.G. Britto,
- Rui Curi and
- Angelo R. Carpinelli
- From the Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil
The presence of a phagocyte-like NAD(P)H oxidase in pancreatic β-cells was investigated. Three NAD(P)H oxidase components were found in pancreatic islets by RT-PCR: gp91PHOX, p22PHOX, and p47PHOX. The components p67PHOX and p47PHOX were also demonstrated by Western blotting. Through immunohistochemistry, p47PHOX was mainly found in the central area of the islet, confirming the expression of this component by insulin-producing cells. Activation of NAD(P)H oxidase complex in the β-cells was also examined by immunohistochemistry. The pancreatic islets presented slower kinetics of superoxide production than HIT-T15 cells, neutrophils, and macrophages, but they reached 66% that of the neutrophil nitroblue tetrazolium (NBT) reduction after 2 h of incubation. Glucose (5.6 mmol/l) increased NBT reduction by 75% when compared with control. The involvement of protein kinase C (PKC) in the stimulatory effect of glucose was confirmed by incubation of islets with phorbol myristate acetate (a PKC activator) and bysindoylmaleimide (GF109203X) (a PKC-specific inhibitor). Diphenylene iodonium [an NAD(P)H oxidase inhibitor] abolished the increase of NBT reduction induced by glucose, confirming the NAD(P)H oxidase activity in pancreatic islets. Because reactive oxygen species are involved in intracellular signaling, the phagocyte-like NAD(P)H oxidase activation by glucose may play an important role for β-cell functioning.
Address correspondence and reprint requests to Dr. Angelo R. Carpinelli, Department of Physiology and Biophysics, Institute of Biomedical Sciences, University of Sao Paulo, Av. Prof. Lineu Prestes, 1524, CEP: 05508-900, Sao Paulo, Brazil. E-mail:.
Received for publication 9 December 2002 and accepted in revised form 24 February 2003.
ABC, avidin-biotin complex; DPI, diphenylene iodonium; KH, Krebs-Henseleit; PB, phosphate buffer; PKC, protein kinase C; PMA, phorbol myristate acetate; NBT, nitroblue tetrazolium; ROS, reactive oxygen species; VSMC, vascular smooth muscle cell.