Protein kinase C activity in rat renal proximal tubule cells.
The presence of protein kinase C (PKC) in proximal tubule cells of the rat kidney is established by means of immunodetection and by the demonstration of calcium- and phospholipid-dependent, staurosporine-inhibitable histone phosphorylation. The calcium-dependence of renal PKC is described. Maximal activation of the enzyme (178.2 and 258.8 pmol P1 mg-1 min-1 for cytosol and membrane respectively) was achieved with 5 microM of Ca2+. Phorbol 12, 13 dibutyrate (PDBu) translocated PKC from cytosol to membrane in a dose- and time-dependent fashion, while 4 alpha-phorbol 12,13-didecanoate produced no significant effect on translocation. Cytosolic PKC activity was compared in immature and mature tissues (10- and 40-day-old kidneys). Basal activity was found to be significantly higher (P less than 0.05) in immature cells (272.8 vs. 157.5 pmol Pi mg-1 min-1). PDBu at 10(-6) M for 15 min reduced immunoreactivity in the soluble fraction of both groups, which was accompanied by a significant decrease in kinase activity. We speculate that the high PKC activity in the infant kidney plays a role in cell growth.
Mendez
C F
CF
Department of Pediatrics, St Göran's Children's Hospital, Karolinska Institute, Stockholm, Sweden.
Hansson
A
A
Skoglund
G
G
Ingelman-Sundberg
M
M
Aperia
A
A
D000375:Aging / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D015151:Immunoblotting; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D007668:Kidney / Q000254:growth & development; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000201:enzymology*; D008297:Male; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013347:Subcellular Fractions / Q000187:drug effects / Q000201:enzymology
D007202:Indicators and Reagents; D015240:Phorbol 12,13-Dibutyrate; D011493:Protein Kinase C; D002118:Calcium