Cullin-associated and neddylation-dissociated 1 protein (CAND1) governs cardiac hypertrophy and heart failure partially through regulating calcineurin degradation

Pathological cardiac hypertrophy is a process characterized by significant disturbance of protein turnover. Cullin-associated and Neddylation-dissociated 1 (CAND1) acts as a coordinator to modulate substrate protein degradation by promoting the formation of specific cullin-based ubiquitin ligase 3 complex in response to the accumulation of specific proteins, which thereby maintains the normal protein homeostasis. However, whether CAND1 titrates the degradation of hypertrophic related proteins and manipulates cardiac hypertrophy remains unknown. In this study, we found that the protein level of CAND1 was increased in the heart tissues from heart failure (HF) patients and TAC mice. CAND1-KO+/- aggravated TAC-induced cardiac hypertrophic phenotypes; in contrast, CAND1-Tg attenuated the maladaptive cardiac remodeling. At the protein level, CAND1 overexpression downregulated, whereas CAND1-KO+/- or knockdown upregulated the expression of calcineurin, a critical pro-hypertrophic protein at both in vivo and in vitro conditions. Mechanistically, CAND1 overexpression favored, whilst CAND1 knockdown blocked the assembly of Cul1/atrogin1/calcineurin complex, an E3 that renders the ubiquitination and degradation of calcineurin. It turned out that calcineurin ubiquitination was suppressed by CAND1 knockdown, but enhanced by CAND1 overexpression. In addition, overexpression of truncated calcineurin that cannot be recognized by atrogin1 abrogated the antihypertrophic effects of CAND1. Notably, CAND1 deficiency-induced hypertrophic phenotypes were partially rescued by knockdown of calcineurin, and application of exogenous CAND1 prevented TAC-induced cardiac hypertrophy and heart failure. In conclusion, CAND1 exerts a protective effect against cardiac hypertrophy and heart failure partially by inducing the degradation of calcineurin. CAND1 represents a novel, promising therapeutic target for cardiac hypertrophy and heart failure. Keywords: CAND1; heart failure; calcineurin; ubiquitination; cullin1