BMP4 induces HO-1 via a Smad-independent, p38MAPK-dependent pathway in pulmonary artery myocytes.

Journal Article (Journal Article)

Bone morphogenetic proteins (BMPs) are multifunctional cytokines, which play a key role in vascular development and remodeling. Heme oxygenase-1 (HO-1), the rate-limiting enzyme in heme catabolism, has been shown to be protective against vascular and lung injury. In a microarray study, we identified HO-1 as a major target of BMP4 signaling in human pulmonary artery smooth muscle cells (PASMCs), and confirmed the induction of HO-1 mRNA and protein by RT-PCR and Western blotting, respectively. Immunoblotting demonstrated that incubation of PASMCs with BMP4 rapidly phosphorylated Smad1/5 and activated the mitogen-activated protein kinases, p38(MAPK) and ERK1/2, in PASMCs, but not JNK. Using pathway selective inhibitors, the induction of HO-1 mRNA and protein was shown to be dependent on activation of p38(MAPK). Induction was independent of Smad1/5 signaling, since HO-1 mRNA and protein induction was intact in PASMCs harboring mutations in the kinase domain of BMP type II receptor, with disrupted Smad signaling. In addition, adenoviral transfection of kinase-deficient BMPR-II also failed to inhibit BMP4-induced HO-1 expression. In functional studies, the HO-1 inhibitor, ZnPP-IX, partly reversed the growth-inhibitory effects of BMP4, and overexpression of HO-1 in PASMCs inhibited serum-stimulated [3H]-thymidine incorporation. Taken together, these findings show that HO-1 is an important Smad-independent target of BMP signaling in vascular smooth muscle. Inhibition of HO-1 function or expression will further increase the proproliferative capacity of BMPR-II-deficient PASMCs and may thus represent a potential "second hit" necessary for disease manifestation.

Full Text

Duke Authors

Cited Authors

  • Yang, X; Lee, PJ; Long, L; Trembath, RC; Morrell, NW

Published Date

  • November 2007

Published In

Volume / Issue

  • 37 / 5

Start / End Page

  • 598 - 605

PubMed ID

  • 17600318

Electronic International Standard Serial Number (EISSN)

  • 1535-4989

Digital Object Identifier (DOI)

  • 10.1165/rcmb.2006-0360OC

Language

  • eng

Conference Location

  • United States