The etiology and pathogenesis of pulmonary fibrosis is poorly understood. We and others reported that M-CSF/CSF-1, M-CSF-R and downstream AKT activation plays an important role in lung fibrosis in mice models and in I...The etiology and pathogenesis of pulmonary fibrosis is poorly understood. We and others reported that M-CSF/CSF-1, M-CSF-R and downstream AKT activation plays an important role in lung fibrosis in mice models and in IPF patients. To understand potential molecular pathways used by M-CSF-R activation to direct lung fibrosis, we used a novel transgenic mouse model that expresses a constitutively-active form of AKT, myristoylated AKT (Myr-Akt), driven by the c-fms (M-CSF-R) promoter. We were particularly interested in the basal immune state of the lungs of these Myr-Akt mice to assess M-CSF-R-related priming for lung fibrosis. In support of a priming effect, macrophages isolated from the lungs of unchallenged Myr-Akt mice displayed an M2-tropism, enhanced co-expression of M-CSF-R and α-SMA, reduced autophagy reflected by reduced expression of the key autophagy genes Beclin-1, MAP1-Lc3a(Lc3a), and MAP1-Lc3b(Lc3b), and increased p62/STSQM1 expression compared with littermate WT mice. Furthermore, Myr-Akt mice had more basal circulating fibrocytes than WT mice. Lastly, upon bleomycin challenge, Myr-Akt mice showed enhanced collagen deposition, increased F4/80+ and CD45+ cells, reduced autophagy genes Beclin-1, Lc3a, and Lc3b expression, and a shorter life-span than WT littermates. These data provide support that M-CSF-R/AKT activation may have a priming effect which can predispose lung tissue to pulmonary fibrosis.展开更多
Previously, we reported that M-CSF induced monocyte survival through the activation of Akt, p38MAPK and Erk1/2 kinases. Here, we found that Src family kinases were upstream of these kinases and played a central role i...Previously, we reported that M-CSF induced monocyte survival through the activation of Akt, p38MAPK and Erk1/2 kinases. Here, we found that Src family kinases were upstream of these kinases and played a central role in regulating M-CSF-induced monocyte survival. We observed that M-CSF promoted c-Src activation in monocytes and MDMs in a time-dependent manner. Src inhibitors reduced M-CSF-mediated phosphorylation of the M-CSF receptor (M-CSFR), Akt, Erk1/2, and p38 MAPK. We also observed that Src directly phosphorylated the M-CSFR. Notably, the inhibitors blocked phosphorylation of specific tyrosine residues within the M-CSFR. We further demonstrated that the Src inhibitor, PP2, attenuated M-CSF-induced NF-κB activation and M-CSF-induced monocyte survival. These findings indicated that Src family kinases mediate monocyte survival through the regulation of receptor phosphorylation and modulation of downstream signaling events. Thus, we predict that targeting Src family kinases may have therapeutic implication in inflammatory diseases.展开更多
文摘The etiology and pathogenesis of pulmonary fibrosis is poorly understood. We and others reported that M-CSF/CSF-1, M-CSF-R and downstream AKT activation plays an important role in lung fibrosis in mice models and in IPF patients. To understand potential molecular pathways used by M-CSF-R activation to direct lung fibrosis, we used a novel transgenic mouse model that expresses a constitutively-active form of AKT, myristoylated AKT (Myr-Akt), driven by the c-fms (M-CSF-R) promoter. We were particularly interested in the basal immune state of the lungs of these Myr-Akt mice to assess M-CSF-R-related priming for lung fibrosis. In support of a priming effect, macrophages isolated from the lungs of unchallenged Myr-Akt mice displayed an M2-tropism, enhanced co-expression of M-CSF-R and α-SMA, reduced autophagy reflected by reduced expression of the key autophagy genes Beclin-1, MAP1-Lc3a(Lc3a), and MAP1-Lc3b(Lc3b), and increased p62/STSQM1 expression compared with littermate WT mice. Furthermore, Myr-Akt mice had more basal circulating fibrocytes than WT mice. Lastly, upon bleomycin challenge, Myr-Akt mice showed enhanced collagen deposition, increased F4/80+ and CD45+ cells, reduced autophagy genes Beclin-1, Lc3a, and Lc3b expression, and a shorter life-span than WT littermates. These data provide support that M-CSF-R/AKT activation may have a priming effect which can predispose lung tissue to pulmonary fibrosis.
文摘Previously, we reported that M-CSF induced monocyte survival through the activation of Akt, p38MAPK and Erk1/2 kinases. Here, we found that Src family kinases were upstream of these kinases and played a central role in regulating M-CSF-induced monocyte survival. We observed that M-CSF promoted c-Src activation in monocytes and MDMs in a time-dependent manner. Src inhibitors reduced M-CSF-mediated phosphorylation of the M-CSF receptor (M-CSFR), Akt, Erk1/2, and p38 MAPK. We also observed that Src directly phosphorylated the M-CSFR. Notably, the inhibitors blocked phosphorylation of specific tyrosine residues within the M-CSFR. We further demonstrated that the Src inhibitor, PP2, attenuated M-CSF-induced NF-κB activation and M-CSF-induced monocyte survival. These findings indicated that Src family kinases mediate monocyte survival through the regulation of receptor phosphorylation and modulation of downstream signaling events. Thus, we predict that targeting Src family kinases may have therapeutic implication in inflammatory diseases.
