Chronic TPA treatment inhibits expression of proximal tubule-specific properties by LLC-PK1 cells.
Confluent LLC-PK1 cell populations expressed progressively proximal tubule-specific properties, including gamma-glutamyl transpeptidase activity, sodium hexose symport activity, alkaline phosphatase activity, and villin protein. This was paralleled by an increase in villin protein manifested at the single cell level. Chronic treatment with 12-O-tetradecanoylphorbol 13-acetate (TPA) inhibited expression of proximal tubule-specific properties at the levels of enzyme activity, protein content, and mRNA content. Inhibition occurred in all cells of the population. TPA treatment induced a decrease in total protein kinase C (PKC)-alpha protein content and a change in subcellular localization from predominantly soluble to predominantly particulate. PKC-epsilon protein content was unchanged by TPA treatment. PKC-epsilon was localized in both soluble and particulate fractions of control cells but was localized predominantly in particulate fractions after TPA treatment. PKC-delta was barely detectable in control cells, but content was markedly increased by TPA. These results suggest that TPA-induced inhibition of expression of proximal tubule-specific properties is mediated through modulation of content and/or subcellular localization of one or more PKC isozymes, likely PKC-alpha.
Amsler
K
K
Department of Physiology and Biophysics, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway 08854, USA.
Murray
J
J
Cruz
R
R
Chen
J L
JL
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism; D002999:Clone Cells; D007527:Isoenzymes / Q000378:metabolism; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018374:LLC-PK1 Cells; D008840:Microfilament Proteins / Q000378:metabolism; D011493:Protein Kinase C / Q000378:metabolism; D011506:Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D013552:Swine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013997:Time Factors; D014018:Tissue Distribution; D005723:gamma-Glutamyltransferase / Q000378:metabolism
D002352:Carrier Proteins; D007527:Isoenzymes; D008840:Microfilament Proteins; D011506:Proteins; D012333:RNA, Messenger; C026615:villin; D005723:gamma-Glutamyltransferase; D011493:Protein Kinase C; D000469:Alkaline Phosphatase; D013755:Tetradecanoylphorbol Acetate