Sex differences in expression and subcellular localization of heart rhythm determinant proteins

To evaluate sex differences in protein expression in the heart, we performed Western blot studies on a subset of Heart Rhythm Determinant (HRD) proteins. We examined key components of a variety of types of mechanical and electrical junctions including, connexin43, plakophilin-2, N-cadherin and plakoglobin, ankyrin-2 and actin. We describe novel findings in sex differences in cardiac protein expression and membrane localization. For most proteins examined, sex differences were significantly more pronounced in the membrane compartment than in overall expression. These studies extend our previous findings in microarray studies to demonstrate that sex differences in gene expression are likely to confer distinct functional properties on male and female myocardium.

Research highlights
► Potential sex differences in protein expression in the mouse heart were assessed by Western blotting.
► Sex differences in key cardiac proteins exist in terms of overall expression and in quantities at intercalated discs.
► Protein expression is affected by estrus cycle stage in female animals.
► Sex differences in membrane localization are not governed by caveolin-3 involvement.