CtBP proteins transactivate matrix metalloproteinases and proinflammatory cytokines to mediate the pathogenesis of abdominal aortic aneurysm.

Abdominal aortic aneurysm (AAA) is a life-threatening disorder that occurs in the aorta. The inflammatory thickness of the aneurysm wall and perianeurysmal fibrosis are two main causes of AAA pathogenesis; however, the molecular mechanisms involved in these two processes are still unclear. We discovered that C-terminal binding protein 1 (CtBP1) and CtBP2 were overexpressed in the aortas of AAA-model mice created by treatment with CaCl and elastase. Molecular analyses revealed that the CtBP heterodimer couples with histone acetyltransferase p300 and transcription factor AP1 (activator protein 1) to transactivate a set of matrix metalloproteinases (MMPs, including MMP1a, 3, 7, 9, and 12) and proinflammatory cytokines, including interleukin-1 β (IL-1β), IL-6, and tumor necrosis factor-alpha (TNF-α). Knockdown of CtBPs or AP1 subunits or blockage of CtBPs with specific small molecule inhibitors significantly suppressed the in vitro expression of MMPs and proinflammatory cytokines. The administration of CtBP inhibitors in AAA-model mice also inhibited MMPs and proinflammatory cytokines, thereby improving the AAA outcome. Taken together, our results revealed a new regulatory mechanism involving MMPs and proinflammatory cytokines in the pathogenesis of AAA. This discovery suggests that targeting CtBPs may be a therapeutic strategy for AAA by attenuating the inflammatory response and matrix destruction.