Expression of isoforms of NADPH oxidase components in rat pancreatic islets.
Increased oxidative stress plays a role in the pathogenesis of beta-cell dysfunction and death. We studied isoforms of NADPH oxidase components in islets of Langerhans isolated from rat pancreas and tumoral rat beta-cell line RINm5F cells by RT-PCR and sequencing of its products. RT-PCR revealed that isolated islets constitutively expressed mRNA of NADPH oxidase components, Nox1, Nox2, Nox4 and p22(phox) as membrane-associated components and p47(phox), Noxo1 (homologue of p47(phox)), Noxa1 (homologue of p67(phox)), and p40(phox) as cytosolic components. RINm5F cells showed a similar pattern of expression but Nox2 mRNA was not detected. Expression of Nox1, Nox4, Noxo1 and Noxa1 was confirmed by sequencing the PCR products. Immunohistochemistry revealed the expression of NADPH oxidase component in beta-cells of rat pancreatic islets. Glucose-stimulated insulin secretion from isolated islets was suppressed by diphenyleneiodonium, a flavocytochrome inhibitor, but not by apocynin, an inhibitor of p47(phox) translocation to membranes. Our results suggest that the functional significance of NADPH oxidase in insulin secretion may merit further investigation.
Uchizono
Yuji
Y
Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan.
Takeya
Ryu
R
Iwase
Masanori
M
Sasaki
Nobuhiro
N
Oku
Miwako
M
Imoto
Hirofumi
H
Iida
Mitsuo
M
Sumimoto
Hideki
H
D000818:Animals; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000201:enzymology / Q000378:metabolism; D003600:Cytosol / Q000201:enzymology / Q000378:metabolism; D015870:Gene Expression; D007150:Immunohistochemistry; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000201:enzymology* / Q000378:metabolism; D007527:Isoenzymes; D008297:Male; D019255:NADPH Oxidases / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction
D007328:Insulin; D007527:Isoenzymes; D012333:RNA, Messenger; D019255:NADPH Oxidases