Numerous experimental studies have demonstrated the role of
cytochrome P450 1B1 (CYP1B1) and its associated mid-chain
hydroxyeicosatetraenoic acids (mid-chain HETEs) metabolite in the pathogenesis of
cardiac hypertrophy. However, the ability of
isoproterenol (ISO) to induce
cardiac hypertrophy through mid-chain HETEs has not been investigated yet. Therefore, we hypothesized that ISO induces
cardiac hypertrophy through the induction of CYP1B1 and its associated mid-chain
HETE metabolites. To test our hypothesis, Sprague-Dawley rats were treated with ISO (5 mg/kg i.p.) for 12 and 72 h whereas, human ventricular cardiomyocytes RL-14 cells were exposed to 100 μM ISO in the presence and absence of 0.5 μM tetramethoxystilbene (TMS) a selective CYP1B1 inhibitor, or 25 nM CYP1B1-siRNA. Moreover, RL-14 cells were transiently transfected with the CRISPR-CYP1B1 plasmid. Thereafter, real-time PCR, western blot analysis, and liquid chromatography-electrospray ionization mass spectroscopy were used to determine the level of gene expression,
protein expression, and mid-chain HETEs, respectively. Our results showed that ISO induced CYP1B1
protein expression and the level of cardiac mid-chain HETEs in vivo at pre-hypertrophic and hypertrophic stage. In vitro, inhibition of CYP1B1 using TMS or CYP1B1-siRNA significantly attenuates ISO-induced
hypertrophy. Furthermore, overexpression of CYP1B1 significantly induced cellular
hypertrophy and mid-chain HETEs metabolite. Mechanistically, the protective effect of TMS against
cardiac hypertrophy was mediated through the modulation of
superoxide anion,
mitogen-activated protein kinases (MAPKs), and nuclear factor-κB (NF-κB). In conclusion, our study provides the first evidence that CYP1B1 and its associated mid-chain
HETE metabolites are directly involved in the ISO-induced
cardiac hypertrophy.