P750Characterisation of the effects of sex and oestrogen receptor beta in the mouse cardiac proteome under pressure overload

Purpose: The response of the heart to pressure overload (PO) differs considerably between males and females. We and others have previously shown that oestrogen receptor (ER) β may be cardioprotective. However, the underlying mechanisms remain incompletely defined. Our aim was the analysis of the effects of sex and ERβ in PO applying a proteomic approach. Methods: Two-month-old C57BL6 male (M) and female (F) wild-type (WT) and ERβ knockout (BERKO) mice were subjected to transverse aortic constriction (TAC) or sham surgery (n = 4/group). The proteome of left ventricular samples was separated by high-resolution 2-dimensional polyacrylamide gel electrophoresis. The proteomic data were analysed with empirical Bayesian-based linear models using the R and Bioconductor software. Results: At nine weeks post operation, TAC led to a greater increase in heart-weight-to-tibia-length ratio in WT M (TAC vs. sham 128%; P < 0.05) than in WT F (TAC vs. sham 54%; P < 0.05) mice, while this difference in BERKO mice between M (TAC vs. sham 53%; P < 0.05) and F (TAC vs. sham 55%; P < 0.05) was abolished. With the present proteomic approach, we were able to identify and analyse a total of 795 left ventricular protein spots. Our comparative proteomic analysis revealed that in WT M and F mice 82 and 31 protein spots, respectively, differed between sham and TAC (P ≤ 0.05). In BERKO M and F mice we found 114 and 87 altered protein spots, respectively (P ≤ 0.05). Overall, mitochondrial bioenergetics- and oxidative stress-related proteins were modulated. We also found that trifunctional enzyme subunit family members were repressed in M-WT-TAC mice, while cytoskeletal proteins were induced in F-WT-TAC mice. On the other hand, heat shock proteins were induced in both M and F-BERKO-TAC mice. Conclusions: Our findings demonstrate that both sex and ERβ influence the proteomic response of the heart to PO. Collectively, we consider our study a useful resource for the unravelling of the effects of sex and ERβ in PO.