Ubiquitin-Specific Peptidase 8 Mediates Angiotensin-II-Induced Smooth Muscle Cell Phenotypic Transformation during Hypertension via Regulating LRRC8A

BACKGROUND: Leucine-rich repeat-containing protein 8 A (LRRC8A) has been uncovered to play a role in pulmonary vascular remodeling during hypertension. The present study aims to investigate a novel mechanism involving LRRC8A in smooth muscle cell (SMC) phenotypic transformation under the hypertension context. METHODS: Angiotensin (Ang)-II-treated human aortic SMCs were established as the cell model under the hypertension context. Western blot and reverse-transcription quantitative polymerase chain reaction were used to detect the levels of target genes. Cell viability and proliferation were evaluated by cell counting kit 8 and 5-ethynyl-2'-deoxyuridine assays, and migration and invasion assays were applied to assess the abilities to migrate and invade of SMCs. The interaction between LRRC8A and ubiquitin-specific protein 8 (USP8) was predicted by the Ubibrowser database and verified by co-immunoprecipitation assay, respectively. RESULTS: LRRC8A was upregulated in Ang-II-treated SMCs, the silence of which reduced cell proliferation, migration, and invasion and increased the expression of contractile proteins (α-SMA, alpha-smooth muscle actin; SM22α, SM22 alpha). USP8 modulated the ubiquitination-modifying levels on LRRC8A protein, and USP8 promoted SMC phenotypic transformation depending on its deubiquitination function. LRRC8A overexpression reversed the repressed cell phenotypic transformation mediated by USP8 silence, and USP8 might accelerate vascular remodeling partly by activating the LRRC8A/PI3K/AKT axis during hypertension. CONCLUSION: LRRC8A upregulation involves in SMC phenotypic transformation under the hypertension context; USP8 can modulate LRRC8A expression in a deubiquitination-dependent manner to further regulate the downstream PI3K/AKT axis during hypertension, which may provide novel therapeutic targets for hypertension management.