title: Inhibition of astroglia-induced endothelial differentiation by inorganic lead: a role for protein kinase C.
abstract: Microvascular endothelial function in developing brain is particularly sensitive to lead toxicity, and it has been hypothesized that this results from the modulation of protein kinase C (PKC) by lead. We examined the effects of inorganic lead on an in vitro model of central nervous system endothelial differentiation in which astroglial cells induce central nervous system endothelial cells to form capillary-like structures. Capillary-like structure formation within C6 astroglial-endothelial cocultures was inhibited by lead acetate with 50% maximal inhibition at 0.5 microM total lead. Inhibition was independent of effects on cell viability or growth. Under conditions that inhibited capillary-like structure formation, we found that lead increased membrane-associated PKC in both C6 astroglial and endothelial cells. Prolonged exposure of C6 cells to 5 microM lead for up to 16 h resulted in a time-dependent increase in membranous PKC as determined by immunoblot analysis. Membranous PKC increased after 5-h exposures to as little as 50 nM lead and was maximal at approximately 1 microM. Phorbol esters were used to determine whether PKC modulation was causally related to the inhibition of endothelial differentiation by lead. Phorbol 12-myristate 13-acetate (10 nM) inhibited capillary-like structure formation by 65 +/- 5%, whereas 4 alpha-phorbol 12,13-didecanoate was without effect. These findings suggest that inorganic lead induces cerebral microvessel dysfunction by interfering with PKC modulation in microvascular endothelial or perivascular astroglial cells.
authors.affiliation: Kennedy Krieger Research Institute, Johns Hopkins Medical Institutions, Baltimore, MD 21205.
authors.forename: J
authors.initials: J
authors.lastname: Laterra
authors.forename: J P
authors.initials: JP
authors.lastname: Bressler
authors.forename: R R
authors.initials: RR
authors.lastname: Indurti
authors.forename: L
authors.initials: L
authors.lastname: Belloni-Olivi
authors.forename: G W
authors.initials: GW
authors.lastname: Goldstein
mesh_terms: D000818:Animals; D001253:Astrocytes / Q000502:physiology*; D002196:Capillaries; D002417:Cattle; D002450:Cell Communication; D002454:Cell Differentiation / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects; D007700:Kinetics; D007854:Lead / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism*; D012160:Retina
chemical_list: D007854:Lead; D011493:Protein Kinase C