HspB8 protein expression in pregnant rat myometrium throughout pregnancy

Marsh, Noelle Lillian (2014) HspB8 protein expression in pregnant rat myometrium throughout pregnancy. Masters thesis, Memorial University of Newfoundland.

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Abstract

Heat shock protein (Hsp) B8 is highly expressed in smooth muscle, but the expression and function in uterine smooth muscle, or myometrium, during pregnancy remains unknown. The goal of this project was to characterize the myometrial expression of HspB8 protein in pregnant rats during myometrial programming. Immunoblot analysis determined that HspB8 and the co-chaperone Bcl2- associated athanogene (Bag) 3 protein expression was elevated at mid-gestation at day (d)15 and d17 (p<0.05; n=4). The intracellular localization of HspB8 and Bag3 has not been well characterized; therefore, spatiotemporal expression in pregnant rat myometrium was also determined by immunofluorescence analysis. HspB8 and Bag3 were predominantly localized to the cytoplasm of myometrial cells and were not found in nuclei. To determine whether an HspB8-Bag3 complex existed in myometrial cells during pregnancy, co-immunoprecipitation assays were performed. The results demonstrated that an HspB8-Bag3 complex was present in vitro and in vivo, at nonpregnant, d15 and d23. This investigation provides valuable insights into the spatiotemporal expression of HspB8 and Bag3 and evidence of formation of a heteromeric signaling complex, HspB8-Bag3, in uterine musculature during pregnancy. With known roles of these proteins in macroautophagy activation, these results suggest that HspB8 and Bag3 could have similar function(s) during myometrial hypertrophy.

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