Smad3-dependent signaling underlies the TGF-β1-mediated enhancement in astrocytic iNOS expression

Mary E. Hamby, James Hewett, Sandra Hewett

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

We previously demonstrated that transforming growth factor-β1 (TGF-β1), while having no effect alone, enhances nitric oxide (NO) production in primary, purified mouse astrocytes induced by lipopolysaccharide (LPS) plus interferon-γ (IFN-γ), by recruiting a latent population of astrocytes to respond, thereby enhancing the total number of cells that express Nos2. In this investigation, we evaluated the molecular signaling pathway by which this occurs. We found that purified murine primary astrocytes express mRNA for TGFbRII as well as the TGFβRI subunit activin-like kinase 5 (ALK5), but not ALK1. Immunofluorescence microscopy confirmed the expression of TGFβRII and ALK5 protein in astrocytes. Consistent with ALK5 signaling, Smad3 accumulated in the nucleus of astrocytes as early as 30 min after TGF-β1 (3 ng/mL) treatment and persisted upto 32 hr after TGF-β1 administration. Addition of ALK5 inhibitors prevented TGF-β1-mediated Smad3 nuclear accumulation and NO production when given prior to the Nos2 induction stimuli, but not after. Finally, astrocyte cultures derived from Smad3 null mutant mice did not exhibit a TGF-β1-mediated increase in iNOS expression. Overall, this data suggests that ALK5 signaling and Smad3 nuclear accumulation is required for optimal enhancement of LPS plus IFNγ-induced NO production in astrocytes by TGF-β1.

Original languageEnglish (US)
Pages (from-to)1282-1291
Number of pages10
JournalGLIA
Volume58
Issue number11
DOIs
StatePublished - Aug 15 2010
Externally publishedYes

    Fingerprint

Keywords

  • ALK5
  • Heterogeneous
  • IFNγ
  • LPS
  • Nitric oxide
  • Primary astrocytes
  • TGFβRI

ASJC Scopus subject areas

  • Cellular and Molecular Neuroscience
  • Neurology

Cite this