Cardiac-Specific Overexpression of Catalytically Inactive Corin Reduces Edema, Contractile Dysfunction, and Death in Mice with Dilated Cardiomyopathy

Abstract

Humans with dilated cardiomyopathy (DCM) and heart failure (HF) develop low levels of corin, a multi-domain, cardiac-selective serine protease involved in natriuretic peptide cleavage and sodium and water regulation. However, experimental restoration of corin levels markedly attenuates HF progression. To determine whether the beneficial effects of corin in HF require catalytic activity, we engineered cardiac overexpression of an enzymatically inactive corin transgene (corin-Tg(i)). On a wild-type (WT) background, corin-Tg(i) had no evident phenotypic effects. However, in a well-established genetic model of DCM, corin-Tg(i)/DCM mice had increased survival (p < 0.01 to 0.001) vs. littermate corin-WT/DCM controls. Pleural effusion (p < 0.01), lung edema (p < 0.05), systemic extracellular free water (p < 0.01), and heart weight were decreased (p < 0.01) in corin-Tg(i)/DCM vs. corin-WT/DCM mice. Cardiac ejection fraction and fractional shortening improved (p < 0.01), while ventricular dilation decreased (p < 0.0001) in corin-Tg(i)/DCM mice. Plasma atrial natriuretic peptide, cyclic guanosine monophosphate, and neprilysin were significantly decreased. Cardiac phosphorylated glycogen synthase kinase-3β (pSer9-GSK3β) levels were increased in corin(i)-Tg/DCM mice (p < 0.01). In summary, catalytically inactive corin-Tg(i) decreased fluid retention, improved contractile function, decreased HF biomarkers, and diminished cardiac GSK3β activity. Thus, the protective effects of cardiac corin on HF progression and survival in experimental DCM do not require the serine protease activity of the molecule.

In Experimental Dilated Cardiomyopathy Heart Failure and Survival Are Adversely Affected by a Lack of Sexual Interactions

“…Male and female (only experimentally used for socialization/breeding) C57BL/6J littermate mice with or without DCM genetic phenotype were used. DCM mice develop progressive HF, in the setting of preserved kidney function, through the action of a transgene containing the CREB S133A transcription factor that is targeted to cardiomyocytes via the alpha myosin heavy chain promoter [13,[16][17][18][19][20][21]. Mice were randomly assigned to groups and housed in one of five lifestyle housing configurations: (1) male DCM + two female wild-type (WT) breeders in one box (DCM+S with access to sexual activity, BD); (2) male DCM cohoused with additional 2-4 male littermates in one box (DCM-S, ND); (3) male DCM cohoused with additional 2-4 males in one box (DCM-S, BD); (4) male DCM housed in boxes with commercially available longitudinal tactile and sensory social hole divider (hole diameter = 0.25" and there are 30/each divider; Unimice Cage Divider Kit w/Social Holes, Animal Care Systems, Centennial, CO) + two WT females on opposite side (DCM+S without access to sexual activity, BD); (5) A subset of male DCM+S mice, breeder diet was shifted to non-breeding cages at 13 weeks of age.…”

“…Transthoracic images in two-dimensional and M-mode parasternal long-axis and short-axis acoustic windows were performed by an echocardiographer blinded to mouse genotype using a Vevo 2100 Imaging System (Visual Sonic Inc., Toronto, Canada) as we have described previously [16,17,19,21]. The ejection fraction (EF, %) from eight of 41 mice has been reported [21].…”

“…Lung edema was assessed by the lung weight-to-body weight ratio (LW/BW, %). The LW/BW was calculated as right lung plus left lung wet weight divided by body weight as described previously [16,17,19,21].…”

“…qRT-PCR reactions were performed in triplicate as described previously [16,17,19,21]. Total RNA was extracted from snap-frozen heart tissue using the RNeasy ® Mini Kit (Qiagen, Germantown, MD, USA).…”

“…In this study we examined the effect of deprivation from sexual activity on pathophysiological outcomes in translationally relevant mouse model of DCM-HF that recapitulates the progressive stages of human HF [13][14][15][16][17][18][19][20][21]. We used human clinical diagnostic modalities (echocardiography and magnetic resonance imaging) to monitor progression of HF [23].…”