FIG. 9.

PEX1 regulates the endogenous ANF gene in cardiomyocytes. (A) Schematic representation of adenovirus constructs expressing LacZ, a PEX1 antisense containing 366 bp of the 5′UTR (AS-PEX1), and another PEX1 antisense containing 442 bp of the 5′UTR and the N-terminal (N-term) coding sequence (HA-AS-PEX1). All adenovirus constructs are driven by the cytomegalovirus (CMV) promoter and have a simian virus 40 (SV40) poly(A) sequence to stabilize the RNA. (B) PEX1 protein levels in cardiomyocytes infected with the AS-PEX1 or the control LacZ adenoviruses as detected by Western blotting. The anti-PEX1 antibody was used with nuclear extracts prepared 4 days postinfection. (C) ANF expression was determined in ventricular cardiomyocytes by using immunohistochemistry, and secreted ANF levels were determined by radioimmunoassay and represent accumulations over 24 h. (D) The level of secreted ANF in the media was determined by radioimmunoassay at 48 and 72 h postinfection with LacZ or AS-PEX1 adenoviruses and chronic treatment with vehicle or 0.1 mM PE. (E) Actin filament organization was examined by using phalloidin-fluorescein isothiocyanate staining in cardiomyocytes infected with LacZ or AS-PEX1 adenoviruses and treated for 48 h with 0.1 mM PE. Note how the cells infected with AS-PEX1 fail to reorganize the myofibrils in response to PE.