ERβ targets ZAK and attenuates cellular hypertrophy via SUMO‐1 modification in H9c2 cells

Abstract

Aberrant expression of leucine zipper- and sterile ɑ motif-containing kinase (ZAK) observed in pathological human myocardial tissue is associated with the progression and elevation of hypertrophy. Our previous reports have correlated high levels of estrogen (E2) and abundant estrogen receptor (ER) α with a low incidence of pathological cardiac-hypertrophy and heart failure in the premenopause female population. However, the effect of elevated ERβ expression is not well known yet. Therefore, in this study, we have analyzed the cardioprotective effects and mechanisms of E2 and/or ERβ against ZAK overexpression-induced cellular hypertrophy. We have used transient transfection to overexpress ERβ into the ZAK tet-on H9c2 cells that harbor the doxycycline-inducible ZAK plasmid. The results show that ZAK overexpression in H9c2 cells resulted in hypertrophic effects, which was correlated with the upregulation of p-JNK and p-p38 MAPKs and their downstream transcription factors c-Jun and GATA-4. However, ERβ and E2 with ERβ overexpressions totally suppressed the effects of ZAK overexpression and inhibited the levels of p-JNK, p-p38, c-Jun, and GATA-4 effectively. Our results further reveal that ERβ directly binds with ZAK under normal conditions; however, ZAK overexpression reduced the association of ZAK-ERβ. Interestingly, increase in ERβ and E2 along with ERβ overexpression both enhanced the binding strengths of ERβ and ZAK and reduced the ZAK protein level. ERβ overexpression also suppressed the E3 ligase-casitas B-lineage lymphoma (CBL) and attenuated CBL-phosphoinositide 3-kinase (PI3K) protein association to prevent PI3K protein degradation. Moreover, ERβ and/or E2 blocked ZAK nuclear translocation via the inhibition of small ubiquitin-like modifier (SUMO)-1 modification. Taken together, our results further suggest that ERβ overexpression strongly suppresses ZAK-induced cellular hypertrophy and myocardial damage.

Regulation of Mitogen-Activated Protein Kinase Signaling Pathways by the Ubiquitin-Proteasome System and Its Pharmacological Potential

“…No study has specifically addressed the regulation of ZAK by the UPS. However, it has been reported that ZAK protein abundance can be modulated by treatment with high concentrations of doxorubicin or by expression of estrogen receptor b in a proteasome-independent manner (Sauter et al, 2010;Pai et al, 2018). In these studies, pharmacological inhibition of the proteasome with MG132 showed no effect on ZAK protein levels.…”

Oestrogen Receptor β Activation Protects Against Myocardial Infarction via Notch1 Signalling

“…In addition, it has been proven that the PI3K/Akt signalling pathway is activated in response to the chronic upregulation of oestrogen receptor β [42]. Furthermore, Notch1 has been demonstrated to modulate the PI3K/Akt axis by regulating PTEN expression in various tissues [43]. These observations prompted us to investigate the relationship between Notch1, PI3K/Akt signalling and oestrogen receptor β activation in damaged cardiac tissue.…”

The Function of SUMOylation and Its Critical Roles in Cardiovascular Diseases and Potential Clinical Implications

“…SUMO1 was also found to improve the oxidative stress response during increased cardiac hypertrophy [ 37 ]. SUMO1 transfection with adenovirus after TAC, a model of heart failure induced by stress overload, prevented the occurrence of cardiac hypertrophy, blocked the negative effect of hydrogen peroxide on SERCA2a, and decreased the oxidative stress index in mice [ 38 ].…”