Role of heterogeneous nuclear ribonucleoprotein A1 in proteomic remodeling before and after plexiform lesion formation in the Sugen/hypoxia rat model

Abstract Background Although plexiform lesions (PLs) formation in severe pulmonary hypertension (PH) are therapeutic targets, the mechanisms of PLs formation have not been fully elucidated. To find candidate proteins involved in PLs formation by comprehensively examining differentially expressed proteins in PH lesions, this study focused on proteomic remodeling before and after the formation of PLs in the SU5416 combined with hypoxia (SuHx) rat model of severe PH using laser capture microdissection coupled with mass spectrometry (LCM–MS). We also determined the mechanisms of PL formation based on the results of proteome analysis. Methods Unobstructed pulmonary arteries with medial hypertrophy (UMPAs) and PLs were morphologically microdissected in SuHx rats and subjected to qualitative and quantitative proteomic analyses, which identified differentially expressed proteins (DEPs) between these structures. In addition, DEPs that may be strongly associated with PLs formation were identified, and functional analysis of one of DEPs was performed using cellular and animal experiments. Results This method identified 718 proteins with 58 DEPs, of which 31 were upregulated in UMPAs and 27 were upregulated in PLs. Immunostaining reconfirmed that DEPs detected in our proteomic analysis were differentially expressed between UMPAs and PLs. Among them, we focused on heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1) as a candidate protein that may be strongly associated with PLs formation. Notably, siRNA knockdown of hnRNPA1 in hypoxia-induced PA smooth muscle cells reduced pyruvate kinase M2 expression and resulted in a significant decrease in proliferative capacity. The treatment of SuHx rats with hnRNPA1 inhibitors also suppressed PA remodeling in PH. and PLs formation. Conclusions We report for the first time, several DEPs that may be associated with the PLs formation, whose relevance to PA remodeling in PH. is unclear. Among these DEPs, hnRNPA1 may play a significant role in PLs formation. The prognosis for PH with PLs is poor and further research is needed on hnRNPA1, which is expected to inhibit PLs formation.