Heterozygous knockout of neuregulin-1 gene in mice exacerbates doxorubicin-induced heart failure

Abstract

Neuregulins and their erbB receptors are essential for cardiac development and postulated to be cardioprotective in the presence of injury in the postnatal heart. We tested the hypothesis that the development of doxorubicin-induced cardiotoxicity in vivo is more severe in mice with heterozygous knockout of the neuregulin-1 gene (NRG-1(+/-)) compared with wild-type mice (WT). Three-month old NRG-1(+/-) and WT mice were injected with a single dose of doxorubicin (20 mg/kg ip). Survival was analyzed by the Kaplan-Meier approach. Left ventricular (LV) function and signaling pathways were analyzed 4 days after treatment. Fifteen days after treatment, survival was significantly lower in doxorubicin-treated NRG-1(+/-) mice (NRG-1(+/-)-Dox) compared with doxorubicin-treated WT mice (WT-Dox) (15% vs. 33%, P < 0.01). LV mass was significantly lower in NRG-1(+/-)-Dox but not in WT-Dox compared with nontreated animals. LV systolic pressure and LV midwall fractional shortening were significantly lower in NRG-1(+/-)-Dox compared with WT-Dox mice. LV protein levels of NRG-1, erbB2, and erbB4 receptors were similar in WT-Dox and NRG-1(+/-)-Dox mice. However, levels of phosphorylated erbB2, Akt, and ERK-1/2 were significantly decreased in NRG-1(+/-)-Dox compared with WT-Dox mice. A significant decrease in phosphorylated P70S6K levels was also observed in NRG-1(+/-)-Dox compared with nontreated NRG-1(+/-) mice. These results demonstrate that heterozygous knockout of the neuregulin-1 gene worsens survival and LV function in the presence of doxorubicin-induced cardiac injury in vivo. This is associated with the depression of activation of the erbB2 receptor as well as Akt, p70S6K, and ERK-1/2 pathways.

erbB2 is required for G protein-coupled receptor signaling in the heart

“…Heterozygous NRG1 (NRG1ϩ͞Ϫ) mutant mice are more susceptible to doxorubicin-induced heart failure. Doxorubicin treatment results in decreased phosphorylated Erk1͞2 levels in NRG1ϩ͞Ϫ mice compared with controls (14). Finally, GPCR agonists are important in cardiac homeostasis (15).…”

Neuregulin1-ErbB Signaling in Doxorubicin-Induced Cardiotoxicity

“…However, decreased activation of the Neuregulin-ErbB signaling does not further increase anthracycline drug doxorubicin or daunorubicin-induced apoptosis as measured by TUNEL staining. In mice with heterozygous knockout of the Neuregulin1 EGF-like domain, the number of TUNELpositive cardiomyocytes was increased in doxorubicin-treated mouse hearts; however, there were no significant differences between doxorubicin-treated wild type and knockout mice (Liu et al, 2005). Similarly, in neonatal and adult rat cardiomyocytes, neither the anti-ErbB2 antibody nor the ErbB2 inhibitor further increased doxorubicin or daunorubicin-induced TUNEL staining (Fukazawa et al, 2003;).…”

“…Studies have been conducted to investigate doxorubicin-induced cardiomyocyte apoptosis in H9c2 rat embryonic cardiomyocytes, neonatal and adult rat cardiomyocytes, as well as in hearts from rats and mice treated with doxorubicin (Childs et al, 2002a;Fukazawa et al, 2003;Liu et al, 2005;Youn et al, 2005;Fu and Arcasoy, 2007;Bian et al, 2009). …”

“…Studies from our laboratory show that doxorubicin induces a worsened cardiac dysfunction in Neuregulin1 knockout mice (Liu et al, 2005). We used heterozygous mice with Neuregulin1 EGF-like domain deletion (Meyer and Birchmeier, 1995).…”

“…Neuregulin1 proteins improve cardiac function in doxorubicin-treated animals (Liu et al, 2005;Liu et al, 2006;Bian et al, 2009). Comparing the two studies, we used recombinant human glial growth factor 2 (GGF2), and a subacute doxorubicin cardiotoxicity mouse model (doxorubicin, 20 mg/kg, i.p.…”