Mini tryptophanyl-tRNA synthetase is required for a synthetic phenotype in vascular smooth muscle cells induced by IFN-γ-mediated ß2-adrenoceptor signaling.

ABSTRACT

Phenotypic modulation of vascular smooth muscle cells (AoSMCs) between quiescent 'contractile' and active 'synthetic' states is crucial in response to normal stimuli and pathological stressors. Previous studies have revealed the ability of interferon gamma (IFN-γ) to activate and promote a synthetic phenotype in AoSMCs that parallels marked up-regulation of truncated tryptophanyl-tRNA synthetase (mini-TrpRS). Here we provide evidence to support an essential dependency of IFN-γ-induced activation and synthetic phenotype in AoSMC on mini-TrpRS. This is based upon change in AoSMC morphology from epithelioid (active synthetic) to spindle-shaped (quiescent contractile) cells and expression of proteins and genes important in mediating or regulating contractile function of AoSMCs, following blockade of mini-TrpRS induced by IFN-γ, via targeted siRNA or the decoy cognate amino acid D-Tryptophan.