{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,16]],"date-time":"2026-10-16T03:54:10Z","timestamp":1792122850874,"version":"4.4.0"},"reference-count":44,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2025,2,5]],"date-time":"2025-02-05T00:00:00Z","timestamp":1738713600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Institutes of Health","award":["HL134610"],"award-info":[{"award-number":["HL134610"]}]},{"name":"National Institutes of Health","award":["HL146369"],"award-info":[{"award-number":["HL146369"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["IJMS"],"abstract":"<jats:p>Pulmonary arterial hypertension (PAH) is characterized by increased lung vascular stiffness and impaired vessel relaxation, primarily due to reduced nitric oxide (NO) production in endothelial cells. Recent studies indicate that chloroquine, an autophagy inhibitor, may help lower pulmonary arterial pressure and enhance lung vascular function. This study investigates the mechanisms underlying the chloroquine-mediated restoration of NO bioavailability in endothelial cells derived from aortopulmonary shunt lambs, a relevant model for congenital heart defect (CHD)-associated PAH. We found that NO production was significantly reduced in shunt pulmonary artery endothelial cells (PAECs), attributable to decreased levels of tetrahydrobiopterin (BH4) and diminished expression of GTP cyclohydrolase 1 (GCH1), despite a slight increase in endothelial nitric oxide synthase (eNOS) levels. Chloroquine robustly restored endothelial NO production, which correlated with increased BH4 levels and restored GCH1 expression. The mechanistically upregulated carboxyl terminus of Hsp70-interacting protein (CHIP) in shunt PAECs is responsible for heightened GCH1 degradation, and chloroquine disrupted the assembly of the GCH1-HSP70-CHIP complex to preserve cellular GCH1. Similarly, another autophagy inhibitor, bafilomycin A1, demonstrated comparable effects. These findings suggest that autophagy inhibition can effectively enhance NO synthesis in endothelial cells experiencing depleted NO bioavailability, presenting a potential therapeutic strategy for managing PAH.<\/jats:p>","DOI":"10.3390\/ijms26031352","type":"journal-article","created":{"date-parts":[[2025,2,6]],"date-time":"2025-02-06T04:47:31Z","timestamp":1738817251000},"page":"1352","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":6,"title":["Chloroquine Restores eNOS Signaling in Shunt Endothelial Cells via Inhibiting eNOS Uncoupling"],"prefix":"10.3390","volume":"26","author":[{"given":"Ying","family":"Liang","sequence":"first","affiliation":[{"name":"Center for Translational Science, Florida International University, Port Saint Lucie, FL 34987, USA"},{"name":"Department of Environmental Health Sciences, Florida International University, Miami, FL 33199, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Wojciech","family":"Ornatowski","sequence":"additional","affiliation":[{"name":"Center for Translational Science, Florida International University, Port Saint Lucie, FL 34987, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qing","family":"Lu","sequence":"additional","affiliation":[{"name":"Center for Translational Science, Florida International University, Port Saint Lucie, FL 34987, USA"},{"name":"Department of Environmental Health Sciences, Florida International University, Miami, FL 33199, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xutong","family":"Sun","sequence":"additional","affiliation":[{"name":"Center for Translational Science, Florida International University, Port Saint Lucie, FL 34987, USA"},{"name":"Department of Environmental Health Sciences, Florida International University, Miami, FL 33199, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4561-8608","authenticated-orcid":false,"given":"Manivannan","family":"Yegambaram","sequence":"additional","affiliation":[{"name":"Center for Translational Science, Florida International University, Port Saint Lucie, FL 34987, USA"},{"name":"Department of Environmental Health Sciences, Florida International University, Miami, FL 33199, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Anlin","family":"Feng","sequence":"additional","affiliation":[{"name":"Center for Translational Science, Florida International University, Port Saint Lucie, FL 34987, USA"},{"name":"Department of Environmental Health Sciences, Florida International University, Miami, FL 33199, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yishu","family":"Dong","sequence":"additional","affiliation":[{"name":"Center for Translational Science, Florida International University, Port Saint Lucie, FL 34987, USA"},{"name":"Department of Cellular and Molecular Medicine, Florida International University, Miami, FL 33199, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Saurabh","family":"Aggarwal","sequence":"additional","affiliation":[{"name":"Department of Cellular and Molecular Medicine, Florida International University, Miami, FL 33199, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hoshang J.","family":"Unwalla","sequence":"additional","affiliation":[{"name":"Department of Cellular and Molecular Medicine, Florida International University, Miami, FL 33199, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9740-405X","authenticated-orcid":false,"given":"Jeffrey R.","family":"Fineman","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, University of California, San Francisco, CA 94143, USA"},{"name":"Cardiovascular Research Institute, University of California, San Francisco, CA 94158, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Stephen M.","family":"Black","sequence":"additional","affiliation":[{"name":"Center for Translational Science, Florida International University, Port Saint Lucie, FL 34987, USA"},{"name":"Department of Environmental Health Sciences, Florida International University, Miami, FL 33199, USA"},{"name":"Department of Cellular and Molecular Medicine, Florida International University, Miami, FL 33199, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ting","family":"Wang","sequence":"additional","affiliation":[{"name":"Center for Translational Science, Florida International University, Port Saint Lucie, FL 34987, USA"},{"name":"Department of Environmental Health Sciences, Florida International University, Miami, FL 33199, USA"},{"name":"Department of Cellular and Molecular Medicine, Florida International University, Miami, FL 33199, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,2,5]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"528","DOI":"10.1164\/rccm.202302-0327SO","article-title":"Pulmonary Hypertension: A Contemporary Review","volume":"208","author":"Johnson","year":"2023","journal-title":"Am. 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