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Titolo:
EXPRESSION AND PHORBOL ESTER-INDUCED DOWN-REGULATION OF PROTEIN-KINASE-C ISOZYMES IN OSTEOBLASTS
Autore:
SANDERS JL; STERN PH;
Indirizzi:
NORTHWESTERN UNIV,SCH MED,DEPT MOL PHARMACOL & BIOL CHEM,303 E CHICAGO AVE CHICAGO IL 60611
Titolo Testata:
Journal of bone and mineral research
fascicolo: 12, volume: 11, anno: 1996,
pagine: 1862 - 1872
SICI:
0884-0431(1996)11:12<1862:EAPEDO>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
OSTEO-SARCOMA CELLS; T-LYMPHOMA CELLS; PARATHYROID-HORMONE; BONE-RESORPTION; LINE SAOS-2; PKC-ZETA; ISOFORM; CALCIUM; MEMBER; FAMILY;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
48
Recensione:
Indirizzi per estratti:
Citazione:
J.L. Sanders e P.H. Stern, "EXPRESSION AND PHORBOL ESTER-INDUCED DOWN-REGULATION OF PROTEIN-KINASE-C ISOZYMES IN OSTEOBLASTS", Journal of bone and mineral research, 11(12), 1996, pp. 1862-1872

Abstract

The protein kinase C (PKC) enzyme family consists of at least 11 isozymes in three classes, with characteristic tissue distributions. Phorbol esters activate and ultimately down-regulate phorbol-sensitive isozymes. PKC is a signal transducer in bane, and phorbol esters influencebone resorption. Little is known about specific PKC isozymes in this tissue, however. We describe here the expression and phorbol ester-induced down-regulation of PKC isozymes in osteoblasts. Normal mouse osteoblasts and seven osteoblastic cell lines (rat UMR-106, ROS 17/2.8, ROS 24/1, and human MG-63, G-292, SaOS-2, HOS-TE85) were screened for isozyme expression by Western immunoblotting using isozyme-specific anti-PKC antibodies. The conventional alpha and beta(1) isozymes, but not gamma, were present in each of the osteoblasts examined; PKC-beta(II) was detectable in all but the ROS 24/1 line. PKC-epsilon was expressedin all osteoblasts screened, but other novel PKCs, delta, eta, and theta, were detectable only in select lines. The atypical zeta and i/lambda PKCs were in all osteoblasts examined. To determine the sensitivity of the isozymes to prolonged phorbol ester treatment, normal osteoblasts and the UMR-106 cell line were treated with vehicle or 1 mu M phorbol 12, 13-dibutyrate (PDB) for 1, 3, 6, 12, 24, or 48 h, and Westernblot analysis was performed. Normal and UMR-106 cells showed similar phorbol sensitivities; conventional (alpha, beta(I)) and novel (delta,epsilon, eta) isozymes were down-regulated by prolonged phorbol treatment but atypical isozymes were not. Down-regulation of all sensitive PKCs was detectable within 6 h of phorbol treatment; the novel delta and epsilon isozymes, however, showed more rapid and dramatic down-regulation than conventional isozymes. The observed down-regulation was dose-dependent (0.3-3 mu M) and specific; 48 h treatment with the inactive phorbol, 4 alpha-phorbol 12,13-didecanoate (4 alpha-PDD), failed todown-regulate PDB-sensitive isozymes. The phorbol-induced down-regulation was also reversible; 24 h after withdrawing PDB, all phorbol-sensitive isozymes, except PKC-eta, had recovered at least partially. These studies, the first to characterize thoroughly PKC isozyme expressionin osteoblastic cells from several species, demonstrate that osteoblasts have a characteristic PKC isozyme profile, including both phorbol ester-sensitive and -insensitive isozymes. The time course of down-regulation and the presence of phorbol-insensitive PKCs must be considered in interpreting the effects of phorbol esters on bone remodeling.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 15/07/20 alle ore 13:03:18