Expression of arachidonate 12-lipoxygenase in rat tissues: a possible role in glucagon secretion.
There are three isoforms of arachidonate 12-lipoxygenase in mammals: platelet, leukocyte, and epidermal types. We found in this study that the leukocyte-type enzyme was present in rat pineal gland, lung, spleen, aorta, adrenal gland, spinal cord, and pancreas, as assessed by RT-PCR. Immunohistochemical analysis showed that the enzyme was localized in macrophages in lung and spleen, alpha-cells of pancreatic islet, zona glomerulosa cells of adrenal cortex, and neuronal cells of spinal cord and superior cervical ganglion. The presence of the 12-lipoxygenase in pancreatic alpha-cells was confirmed by glucagon staining in a consecutive section. We overexpressed the leukocyte-type 12-lipoxygenase cDNA in a glucagon-secreting alphaTC clone 6 cell line that had been established from a transgenic mouse. Glucagon secretion was stimulated by approximately twofold in the 12-lipoxygenase-expressing cells compared to the mock-transfected and original cells. The results suggest that the 12-lipoxygenase of the leukocyte type augments glucagon secretion from pancreatic islets.
Kawajiri
H
H
Department of Pharmacology, Kanazawa University School of Medicine, Kanazawa, Japan.
Zhuang
D
D
Qiao
N
N
Yoshimoto
T
T
Yamamoto
M
M
Iseki
S
S
Hamaguchi
K
K
D000818:Animals; D000918:Antibody Specificity; D001092:Arachidonate 12-Lipoxygenase / Q000276:immunology / Q000378:metabolism*; D015153:Blotting, Western; D002460:Cell Line; D005934:Glucagon / Q000378:metabolism*; D007150:Immunohistochemistry; D007515:Islets of Langerhans / Q000378:metabolism; D007962:Leukocytes / Q000201:enzymology; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D009928:Organ Specificity; D010870:Pineal Gland / Q000201:enzymology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction
D012333:RNA, Messenger; D005934:Glucagon; D001092:Arachidonate 12-Lipoxygenase