Age-dependent expression of protein kinase C isoforms in rat islets.
The appearance of the biphasic insulin secretory response several days after birth suggests that maturation of a critical step in stimulus-secretion coupling occurs during the early neonatal period. To clarify the role of protein kinase C (PKC) during this time, we examined the pancreatic islets of adult, 3-day neonatal, and 19-day fetal rats for the presence of different PKC isoenzymes. Western-blot analysis of islet extracts showed the presence of PKC isoforms in both adult and neonatal tissues. Immunocytochemistry of adult islets revealed a differential expression in islet cell types. PKC-alpha was found only in beta-cells, PKC-gamma in alpha-cells, and PKC-epsilon in delta-cells and vascular walls. Immunoreactivity for PKC-beta was not detected in any cell type. All three isoenzymes were also present in neonatal islets; however, in contrast to adult tissue, immunoreactivity for either PKC-alpha or PKC-gamma was present in relatively few cells. There was no apparent immunoreactivity for PKC-alpha or PKC-gamma in fetal islets, although these tissues contained strong staining for insulin and glucagon. These data show that three of the PKC isoforms are restricted to a particular islet cell type, where they may play a unique role in the secretion of a specific hormone. Moreover, our results demonstrate that these enzymes, especially PKC-alpha, appear during the early neonatal period. This age-dependent expression may be linked to the development of the biphasic insulin release response.
Fletcher
D J
DJ
Department of Anatomy and Cell Biology, School of Medicine, East Carolina University, Greenville, North Carolina 27858-4354.
Ways
D K
DK
D000375:Aging / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D005260:Female; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics / Q000502:physiology*; D005934:Glucagon / Q000032:analysis; D007106:Immune Sera; D007150:Immunohistochemistry; D007328:Insulin / Q000032:analysis / Q000378:metabolism; D007515:Islets of Langerhans / Q000196:embryology / Q000201:enzymology* / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D008297:Male; D008969:Molecular Sequence Data; D011247:Pregnancy; D011493:Protein Kinase C / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains
D007106:Immune Sera; D007328:Insulin; D007527:Isoenzymes; D005934:Glucagon; D011493:Protein Kinase C