TACE is required for fetal murine cardiac development and modeling

Tumor necrosis factor-[alpha] converting enzyme (TACE) is a membrane-anchored, Zn-dependent metalloprotease, which belongs to the ADAM (a disintegrin and metalloprotease) family. TACE functions as a membrane sheddase to release the ectodomain portions of many transmembrane proteins, including the precursors of TNF[alpha] , TGF[alpha], several other cytokines, as well as the receptors for TNF[alpha], and neuregulin (ErbB4). Mice with [TACE.sup.[delta]Zn/[delta]Zn] null mutation die at birth with phenotypic changes, including failure of eyelid fusion, hair and skin defects, and abnormalities of lung development. Abnormal fetal heart development was not previously described. Herein, we report that [TACE.sup.[delta]Zn/[delta]Zn] null mutant mice by late gestation exhibit markedly enlarged fetal hearts with increased myocardial trabeculation and reduced cell compaction, mimicking the pathological changes of noncompaction of ventricular myocardium. In addition, larger cardiomyocyte cell size and increased cell proliferation were observed in ventricles of [TACE.sup.[delta]Zn/[delta]Zn] knockout mouse hearts. At the molecular level, reduced expression of epidermal growth factor receptor, attenuated protein cleavage of ErbB4, and changes in MAPK activation were also detected in [TACE.sup.[delta]Zn/[delta]Zn] knockout heart tissues. The data suggest that TACE-mediated cell surface protein ectodomain shedding plays an essential and a novel regulatory role during cardiac development and modeling. Keywords: TACE; Heart development; Cardiomyocyte