Novel Methods Article Detection of protein aggregation and proteotoxicity induced by angiotensin II in vascular smooth muscle cells.

Disruption of protein quality control occurs with aging and cardiovascular pathologies including arterial stiffness and hypertension. Angiotensin II (Ang II) is believed to induce endoplasmic reticulum stress in vascular smooth muscle cells (VSMC), thus contributing to vascular remodeling and dysfunction. However, whether Ang II increases formation of protein aggregates and mediates proteotoxicity in VSMCs remain obscure. Accordingly, the present study aimed to establish a quantitative method of protein aggregate detection induced by Ang II, and to investigate their potential involvement in inflammatory and senescence responses. Proteostat staining showed increased aggregate numbers per cell upon Ang II exposure. Immunoblot analysis further showed an increase in pre-amyloid oligomer presence in a detergent insoluble protein fraction purified from VSMC stimulated with Ang II. Moreover, these responses were attenuated by treatment with chemical chaperone, 4-phenylbutyrate. 4-phenylbutyrate further blocked Ang II induced senescence associated â-galactosidase activity and THP-1 monocyte adhesion in VSMCs. These data suggest that Ang II induces proteotoxicity in VSMCs which likely contributes to aging and inflammation in the vasculature.