title: Regulation of opossum kidney (OK) cell Na/Pi cotransport by Pi deprivation involves mRNA stability.
abstract: Renal proximal tubular Na-dependent phosphate transport (Na/Pi cotransport) has been studied extensively in the opossum kidney (OK) cell line. Recently, we cloned a complementary deoxyribonucleic acid (cDNA) (NaPi-4) from OK cells encoding an apical NaPi cotransport system. OK cells exposed to a low-Pi medium, as compared to high-Pi media, responded with an increase in Na/Pi cotransport, which was followed by an increase in NaPi-4 messenger ribonucleic acid (mRNA) abundance; maximal stimulation of Na/Pi cotransport was reached in 2 h, with no further increase for up to 16 h. NAPi-4 mRNA abundance was unaltered for 2 h, then increased to a maximum after 6-16 h in cells treated with low Pi medium. NaPi-4 mRNA decay rate was lowered by low-Pi media when compared to high-Pi media, with no increase in the NaPi-4 mRNA transcription rate. These data suggest that the upregulation of Na/Pi cotransport in OK cells by low-Pi media involves two regulatory mechanisms: an immediate (early) increase (after 2 h) in the expression of Na/Pi cotransport, independent of mRNA synthesis or stability, and a delayed (late) effect (after 4-6 h), resulting in an increase in NaPi-4 mRNA abundance, due to an increased stability.
mesh_terms: D000818:Animals; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D003609:Dactinomycin / Q000378:metabolism; D003720:Densitometry; D007668:Kidney / Q000378:metabolism*; D009893:Opossums / Q000378:metabolism*; D010710:Phosphates / Q000172:deficiency*; D012333:RNA, Messenger / Q000096:biosynthesis*; D050608:Sodium-Phosphate Cotransporter Proteins; D027981:Symporters; D014158:Transcription, Genetic; D015854:Up-Regulation / Q000502:physiology
chemical_list: D002352:Carrier Proteins; D018076:DNA, Complementary; D010710:Phosphates; D012333:RNA, Messenger; D050608:Sodium-Phosphate Cotransporter Proteins; D027981:Symporters; D003609:Dactinomycin