Sitapara R, Lam TT, Gandjeva A, Tuder RM, Zisman LS. Phosphoproteomic analysis of lung tissue from patients with pulmonary arterial hypertension.
Pulm Circ 2021;
11:20458940211031109. [PMID:
34966541 PMCID:
PMC8711668 DOI:
10.1177/20458940211031109]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Accepted: 06/18/2021] [Indexed: 11/29/2022] Open
Abstract
Pulmonary arterial hypertension (PAH) is a rare disorder associated with high
morbidity and mortality despite currently available treatments. We compared the
phosphoproteome of lung tissue from subjects with idiopathic PAH (iPAH) obtained
at the time of lung transplant with control lung tissue. The mass
spectrometry-based analysis found 60,428 phosphopeptide features from which 6622
proteins were identified. Within the subset of identified proteins there were
1234 phosphopeptides with q < 0.05, many of which are
involved in immune regulation, angiogenesis, and cell proliferation. Most
notably there was a marked relative increase in phosphorylated (S378) IKZF3
(Aiolos), a zinc finger transcription factor that plays a key role in lymphocyte
regulation. In vitro phosphorylation assays indicated that GSK3 alpha and/or
GSK3 beta could phosphorylate IKZF3 at S378. Western blot analysis demonstrated
increased pIKZF3 in iPAH lungs compared to controls. Immunohistochemistry
demonstrated phosphorylated IKZF3 in lymphocytes surrounding severely
hypertrophied pulmonary arterioles. In situ hybrization showed gene expression
in lymphocyte aggregates in PAH samples. A BCL2 reporter assay showed that IKZF3
increased BCL2 promoter activity and demonstrated the potential role of
phosphorylation of IKZF3 in the regulation of BCL mediated transcription. Kinase
network analysis demonstrated potentially important regulatory roles of casein
kinase 2, cyclin-dependent kinase 1 (CDK1), mitogen-associated protein kinases
(MAPKs), and protein kinases (PRKs) in iPAH. Bioinformatic analysis demonstrated
enrichment of RhoGTPase signaling and the potential importance of cGMP-dependent
protein kinase 1 (PRKG). In conclusion, this unbiased phosphoproteomic analysis
demonstrated several novel targets regulated by kinase networks in iPAH, and
reinforced the potential role of immune regulation in the pathogenesis of iPAH.
The identified up- and down-regulated phosphoproteins have potential to serve as
biomarkers for PAH and to provide new insights for therapeutic strategies.
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