Increase in Elastin Gene Expression and Protein Synthesis in Arterial Smooth Muscle Cells Derived From Patients with Moyamoya Disease

Abstract

Background and Purpose Moyamoya disease is a progressive cerebrovascular occlusive disease that is rare in all ages but frequently presents in children. The etiology of the disease is unknown. We examined elastin gene transcripts and elastin synthesis in cultured arterial smooth muscle cells (SMCs) derived from moyamoya patients and compared them with those in SMCs from age-matched control subjects. Methods We used six cell strains from moyamoya patients and four from controls. The expression of elastin protein was observed by Western blot analysis and metabolic labeling with 3 H-valine. Elastin gene transcripts were identified by Northern blot analysis. Results Elastin mRNA and protein levels were elevated in all SMCs from moyamoya patients compared with control SMCs. Although transforming growth factor-β1 (TGF-β1), a potent enhancer of the expression of elastin in arterial SMCs, upregulated elastin mRNA and protein levels in SMCs from both moyamoya patients and control subjects, the maximum levels of elastin synthesis and elastin gene transcripts in response to exogenous TGF-β1 were significantly greater in moyamoya SMCs than control SMCs. In addition, quiescent moyamoya SMCs secreted significantly more TGF-β1 into the culture medium than quiescent control SMCs ( P <.01). Conclusions Our findings suggest that moyamoya disease may result, at least in part, from an abnormal regulation of extracellular matrix metabolism that leads to increased steady state levels of elastin mRNA and elastin accumulation in the intimal thickening and that increased elastin accumulation is a stable marker of SMCs from patients with moyamoya disease.