Zinc-Induced PKCδ-dependent Phosphorylation of MTF-1 Promotes Pulmonary Vascular Remodeling in Hypoxic Pulmonary Hypertension

Pulmonary hypertension (PH) is driven by pulmonary vascular remodeling, in which the zinc-sensing transcription factor metal-responsive transcription factor 1 (MTF-1) may play a pivotal regulatory role.Rodent models of hypoxia-induced PH and cultured pulmonary arterial smooth muscle cells (PASMCs) were used to investigate zinc-mediated MTF-1 activation.Phos-tag SDS-PAGE, site-directed mutagenesis, Cleavage Under Targets and Tagmentation (CUT&Tag), and pharmacological inhibitors were employed to dissect the PKCδ/MTF-1/placental growth factor (PlGF) pathway.CUT&Tag profiling revealed prominent MTF-1 enrichment at promoter regions under hypoxia, with significant occupancy at the Plgf locus and enrichment of angiogenesis-related genes.Hypoxia increased intracellular zinc levels, activated PKCδ, and triggered phosphorylation of MTF-1 at Ser 304 .This modification was essential for MTF-1 nuclear translocation and PlGF transcription.Mutation of Ser 304 or MTF-1 knockdown suppressed PASMCs proliferation and migration under hypoxia and zinc exposure.Gö 6983 abrogated MTF-1 phosphorylation and downstream responses, and selective knockdown of PKCδ reproduced these effects, confirming PKCδ as the predominant isoform mediating MTF-1 activation.In vivo, MTF-1 and PlGF were upregulated in pulmonary vessels of Su/Hx-PH rats, while APTO-253 treatment attenuated pulmonary vascular remodeling and improved cardiopulmonary hemodynamics in hypoxic mice.This study identified PKCδ-dependent phosphorylation of MTF-1 at Ser 304 as a critical mechanism linking zinc accumulation to PlGF-driven PASMCs proliferation.Targeting the zinc/PKCδ/MTF-1/PlGF axis represented a novel therapeutic strategy for hypoxic PH.