A repressor protein, Mnt, is a novel negative regulator of vascular smooth muscle cell hypertrophy by angiotensin II and neointimal hyperplasia by arterial injury.

OBJECTIVE: The Max-interacting protein Mnt is a transcriptional repressor that can antagonize the transcriptional and proliferation-related activities of Myc. Here, we tested the hypothesis that Mnt is a negative regulator of pathological vascular remodeling.
METHODS: Adenovirus encoding Mnt or control GFP was infected to cultured rat vascular smooth muscle cells (VSMC) and carotid arteries after a balloon angioplasty.
RESULTS: In VSMC, adenoviral gene transfer of Mnt suppressed angiotensin II-induced protein expression of early growth response protein-1 (Egr1) and its promoter activation. Mnt adenovirus did not interfere with upstream signaling of angiotensin II. Angiotensin II-induced protein accumulation in VSMC was inhibited by Mnt adenovirus. Mnt adenovirus also inhibited platelet-derived growth factor-induced VSMC proliferation. Moreover, Mnt adenovirus prevented neointima formation in response to arterial injury. The adenoviral Mnt gene transfer also prevented Egr1 induction in neointima.
CONCLUSION: These data identify Mnt as a previously unrecognized negative regulator of pathological vascular remodeling.