ANKRD1 Acts as a Transcriptional Repressor of MMP13 via the AP-1 Site

The transcriptional cofactor ANKRD1 is sharply induced during wound repair, and its overexpression enhances healing. We recently found that global deletion of murineAnkrd1 impairs wound contraction and enhances necrosis of ischemic wounds. A quantitative PCR array ofAnkrd1 −/− (KO) fibroblasts indicated that ANKRD1 regulates MMP genes. Yeast two-hybrid and coimmunoprecipitation analyses associated ANKRD1 with nucleolin, which represses AP-1 activation ofMMP13. Ankrd1 deletion enhanced both basal and phorbol 12-myristate 13-acetate (PMA)-inducedMMP13 promoter activity; conversely,Ankrd1 overexpression in control cells decreased PMA-inducedMMP13 promoter activity.Ankrd1 reconstitution in KO fibroblasts decreasedMMP13 mRNA, whileAnkrd1 knockdown increased these levels.MMP13 mRNA and protein were elevated in intact skin and wounds of KO versusAnkrd1 fl/fl (FLOX) mice. Electrophoretic mobility shift assay gel shift patterns suggested that additional transcription factors bind to theMMP13 AP-1 site in the absence ofAnkrd1 , and this concept was reinforced by chromatin immunoprecipitation analysis as greater binding of c-Jun to the AP-1 site in extracts from FLOX versus KO fibroblasts. We propose that ANKRD1, in association with factors such as nucleolin, repressesMMP13 transcription.Ankrd1 deletion additionally relievedMMP10 transcriptional repression. Nuclear ANKRD1 appears to modulate extracellular matrix remodeling by MMPs.