Parathyroid hormone-related protein increases DNA synthesis in proximal tubule cells by cyclic AMP- and protein kinase C-dependent pathways.
The present study was performed to characterize the possible involvement of cAMP synthesis and protein kinase C (PKC) activation in the DNA synthesis-stimulating effect of parathyroid hormone-related protein (PTHrP) in proximal tubule cells. We found that DNA synthesis was stimulated by 10 microM 8BrcAMP, and 1 microM Sp-cDBIMPS, two cAMP analogs, and also by 1 microM phorbol 12-myristate 13-acetate (PMA) and 100 microM 1,2-dioctanoyl-sn-glycerol, two PKC activators, and 10 nM [Cys23] human (h)PTHrP (24-35) amide in rabbit proximal tubule cells (PTC). Both Sp-cDBIMPS and PMA, at 1 microM, also increased DNA synthesis in SV40-immortalized mouse proximal tubule cells MCT. Human PTHrP (7-34) amide [PTHrP (7-34)] dose dependently stimulated DNA synthesis in a similar manner as [34Tyr]PTHrP (1-34) amide [PTHrP (1-34)], in PTC. PMA pre-treatment for 20 h, which downregulates PKC, completely blocked the effect induced by PTHrP (7-34), but not that of PTHrP (1-34), in the latter cells. In contrast, the same PMA pre-treatment abolished the DNA synthesis stimulation by PTHrP (1-34) and PTHrP (7-34) in MCT cells, which appear to have PTH receptors mainly coupled to phospholipase C and not adenylate cyclase. Our results indicate that the stimulatory effect of PTHrP on DNA synthesis in proximal tubule cells is mediated by a cAMP- and PKC-dependent mechanism.
García-Ocaña
A
A
Research Unit, Fundación Jiménez Díaz, Madrid, Spain.
Gómez-Casero
E
E
Peñaranda
C
C
Esbrit
P
P
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D002472:Cell Transformation, Viral; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis*; D004789:Enzyme Activation; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D010281:Parathyroid Hormone / Q000494:pharmacology*; D044162:Parathyroid Hormone-Related Protein; D011493:Protein Kinase C / Q000378:metabolism*; D011506:Proteins / Q000494:pharmacology*; D011817:Rabbits; D018016:Receptors, Parathyroid Hormone / Q000378:metabolism; D013539:Simian virus 40 / Q000502:physiology*; D010738:Type C Phospholipases / Q000378:metabolism
D010281:Parathyroid Hormone; D044162:Parathyroid Hormone-Related Protein; D011506:Proteins; D018016:Receptors, Parathyroid Hormone; D004247:DNA; D011493:Protein Kinase C; D010738:Type C Phospholipases; D000262:Adenylyl Cyclases