Estrogen increases the expression of uterine protein kinase C isozymes in a tissue specific manner

Abstract

The pattern of protein kinase C isozyme expression in uterine smooth muscle and ventricular cardiac muscle was examined in ovariectomized rats pretreated with estradiol-17β alone or with estradiol-17β and progesterone. Protein kinase C isozyme expression was examined in membrane and cytosolic subcellular fractions by immunoblot analysis using antisera specific for α, γ, β1, β2, δ, ε, ζ, and θ isozymes. All isozymes were detectable in positive control brain extracts. The predominant isozymes in the myometrium were δ and β2 while in the ventricle, β2 and ζ were the dominant forms. In unstimulated tissues, all isozymes except PKC-δ, were predominantly found in the cytosolic compartment. Both estrogen and progesterone increased membrane-associated isozyme expression 35–125% in uterine muscle. Neither estrogen nor progesterone treatment significantly affected protein kinase C expression in cardiac muscle. These data suggest that estradiol, which increases uterine muscle hypertrophy and contractility, may exert these effects by increasing membrane-associated protein kinase C expression in a tissue-specific manner.