Proteasome-dependent degradation of ERalpha but not ERbeta in cultured mouse aorta smooth muscle cells.

• Here we investigate ERα and ERβ expression and regulation in vascular smooth muscle cells from mouse aorta. Immunocytochemistry showed nuclear staining for both ERα and ERβ. Double stainings revealed co-expression of ERα and ERβ in vascular smooth muscle cells. ERα (66 kDa) and ERβ (54 kDa) expression determined by Western blotting was unchanged within 7 h after inhibition of protein synthesis with cycloheximide in the absence of 17β-estradiol (E2), showing that both proteins are stable without ligand-binding. Treatment with 10 nM E2 for 7 h in the presence of cycloheximide increased ERα, suggesting that E2 causes a conformational change in the ERα protein. The ERβ was not affected by E2. Treatment with the proteasome inhibitor epoxomicin (100 nM) for 3 days caused a prominent upregulation of ERα both in the absence and in the presence of E2, while ERβ was unaffected, suggesting that ERα but not ERβ is degraded by ubiquitin–proteasome system in vascular smooth muscle cells. In summary, we disclose a short-term regulation of ERα protein by estrogen and that ERα but not ERβ is degraded via the ubiquitin–proteasome pathway in vascular smooth muscle cells.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Endokrinologi och diabetes (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- Endocrinology and Diabetes (hsv//eng)

Nyckelord

Immunocytochemistry

Estrogen receptor α and β

Estrogen

Vascular smooth muscle cells

Western blotting

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