Osteopontin plays important roles in pulmonary arterial hypertension induced by systemic‐to‐pulmonary shunt

Abstract

Recent studies indicated that osteopontin (OPN) was involved in the genesis and progression of pulmonary arterial hypertension (PAH); however, its role in congenital heart disease–associated PAH (CHD/PAH) remains unknown. Our results showed that OPN was increased in lungs and plasma of patients with Eisenmenger syndrome; moreover, OPN and αvβ3‐integrin expression levels were augmented in rat lungs exposed to systemic‐to‐pulmonary shunt. Cell culture assay demonstrated that distal pulmonary arterial smooth muscle cells (PASMCs) from rat lungs suffering from volume and pressure overload exhibited enhanced proliferation compared with those from healthy rats. Mechanical stretch (20% at 1 Hz) increased OPN expression and activated ERK1/2 and protein kinase B (Akt) signal pathway in distal PASMCs from healthy rats. Interestingly, OPN enhanced the proliferation and migration of PASMCs while blocking αvβ3‐integrin with neutralizing antibody LM609 or Arg‐Gly‐Asp peptidomimetic antagonist cyclo(Ala‐Arg‐Gly‐Asp‐3‐aminomethylbenzoyl) (XJ735), rectified the proliferative and migratory effects of OPN, which were partially mediated via ERK1/2 and Akt signaling pathways. Furthermore, surgical correction of systemic‐to‐pulmonary shunt, particularly XJ735 supplementation after surgical correction of systemic‐to‐pulmonary shunt, significantly alleviated the pulmonary hypertensive status in terms of pulmonary hemodynamic indices, pulmonary vasculopathy, and right ventricular hypertrophy. In summary, OPN alteration in lungs exposed to systemic‐to‐pulmonary shunt exerts a deteriorative role in pulmonary vascular remodeling through modulating the proliferation and migration of PASMCs, at least in part, via αvβ3‐ERKl/2 and αvβ3‐Akt signaling pathways. Antagonizing OPN receptor αvβ3‐integrin accelerated the regression of pulmonary vasculopathy after surgical correction of systemic‐to‐pulmonary shunt, indicating a potential therapeutic strategy for patients with CHD/PAH.—Meng, L., Liu, X., Teng, X., Gu, H., Yuan, W., Meng, J., Li, J., Zheng, Z., Wei, Y., Hu, S. Osteopontin plays important roles in pulmonary arterial hypertension induced by systemic‐to‐pulmonary shunt. FASEB J. 33, 7236–7251 (2019). http://www.fasebj.org

Post-translational regulation and proteolytic activity of the metalloproteinase ADAMTS8

“…From N-terminus to Cterminus, these include the arginine-glycine-aspartic acid (RGD) cell-binding sequence, a serinevaline-valine-tyrosine-glycine-leucine-arginine (SVVYGLR) domain, mediating the interaction between OPN and integrin receptors α4β1 and α9β1, a calcium-binding site and a heparin-binding site. Our LC-MS analysis of OPN digests by ADAMTS8 identified cleavage sites at Tyr 33 -Asn 34 , Asn 53 -Leu 54 , Asp 217 -Asp 218 , Ser 225 -His 226 , His 226 -Lys 227 , Gln 228 -Ser 229 , Ser 229 -Arg 230 , Glu 251 -Leu 252 , Glu 263 -Phe 264 , and Phe 264 -His 265 . Three of these, Asn 53 -Leu 54 , Asp 217 -Asp 218 and Gln 228 -Ser 229 , were significant already after 2 h digestion.…”

“…The gene found to be most consistently upregulated was Spp1 , coding for secreted phosphoprotein 1 or osteopontin (OPN) ( Table S2 ). OPN stimulates growth and migration of PAH SMCs ( 33 , 34 ) and contributes to the highly proliferative, migratory and proinvasive phenotype exhibited by adventitial fibroblasts in PAH ( 35 ). OPN plasma levels increase in patients with PAH ( 33 , 35 , 36 , 37 ) and correlate with disease severity ( 37 ) and mortality ( 36 , 38 ).…”

“…7B). These included semi-tryptic C-terminal peptides indicating proteolysis at Tyr 33 -Asn 34 , Ser 225 -His 226 , His 226 -Lys 227 , Ser 229 -Arg 230 , and Glu 251 -Leu 252 , and the N-terminal semi.tryptic peptides indicating proteolysis at Glu 263 -Phe 264 , and Phe 264 -His 265 . Two peptides indicating proteolysis at Phe 264 -His 265 were found, one unmodified and another with an oxidized methionine residue at position 270.…”

“…-Asn34 , Asn53 -Leu54 , Asp 217 -Asp 218 , Ser 225 -His 226 , His 226 -Lys 227 , Gln 228 -Ser 229 , Ser 229 -Arg 230 , Glu 251 -Leu 252 , Glu 263 -Phe 264 , and Phe 264 -His 265 are likely sites of ADAMTS8 cleavage of OPN (Fig.…”

Screening of Hub Genes Associated with Pulmonary Arterial Hypertension by Integrated Bioinformatic Analysis

“…The comprehensive analysis showed that the high expression of SPP1 should be a driver of PAH. It has been reported that SPP1 plays a role in PAH via enhancing pulmonary vascular smooth muscle cell (PVSMC) proliferation [50,51]. The expression level of SPP1 was related to the severity of PAH [52,53].…”