Small heat shock protein 27 (Hsp27) expression is highly induced in rat myometrium during late pregnancy and labour

Abstract

The underlying mechanisms that regulate uterine contractions during labour are still poorly understood. A candidate regulatory protein is heat shock protein 27 (Hsp27). It belongs to the small heat shock protein family and can regulate actin cytoskeleton dynamics, act as a chaperone, and may regulate contractile protein activation. As a result, we hypothesized that Hsp27 expression would be highly induced during late pregnancy and labour. Hsp27 mRNA expression was significantly elevated (P < 0.05) on days 17 to 22 of gestation. In addition, immunoblot analysis demonstrated that detection of total Hsp27 increased (P < 0.05) between day 21 and 1 day post-partum (PP) inclusive. Since phosphorylation of Hsp27 has been reported to be a prerequisite for smooth muscle contraction, we examined the temporal and spatial expression of Ser-15 phosphorylated Hsp27. Immunoblot analysis showed that the detection of Ser-15 phosphorylated Hsp27 significantly increased (P < 0.05) between days 19 and 23 (active labour) inclusive, in parallel with detection of total Hsp27. Immunocytochemical analysis of Ser-15 phosphorylated Hsp27 expression in situ demonstrated that phosphorylated Hsp27 in circular muscle became detectable in peri-nuclear and membrane regions on days 19 to 22, but was primarily restricted to the cytoplasm on days 23 to PP. In contrast, phosphorylated Hsp27 in longitudinal muscle was primarily detected in myocyte membranes on days 15 to 22, and then also became detectable in the cytoplasm of myocytes on days 23 and PP. Our results demonstrate that Hsp27 expression is highly upregulated during late pregnancy and labour and suggest that Hsp27 is a potential candidate contraction-associated protein.

Differential expression of alphaB-crystallin and Hsp27-1 in anaplastic thyroid carcinomas because of tumor-specific alphaB-crystallin gene (CRYAB) silencing

“…AlphaB-crystallin expression has also been demonstrated to varying extent in numerous epithelial tumors (Pinder et al 1994). Similarly, Hsp27-1 expression was found in various benign and malignant tissues, eg, in retinal neurons (Whitlock et al 2005a(Whitlock et al , 2005b, in reproductive tissues (White et al 2005), in normal and neoplastic renal tissue (Neuhofer et al 2005;Tremolada et al 2005), and in malignant thyroid tissue (Akslen and Varhaug 1995).…”

Distension of the uterus induces HspB1 expression in rat uterine smooth muscle

“…We previously reported that HspB1 gene expression is highly upregulated in the rat myometrium during late pregnancy and labor (49); this finding parallels the increase in mechanical stress or distension exerted on the myometrium due to growing fetuses. It was also reported that, during late pregnancy, Ser 15 -phosphorylated HspB1 (pSer 15 HspB1) had a predominantly membrane-associated localization in situ within cells of the circular and longitudinal muscle layers.…”

“…Uterine horn samples to be used for immunocytochemical analysis were fixed in 4% paraformaldehyde in 1ϫ PBS overnight with agitation and then washed in 1ϫ PBS for 24 h. Tissue samples were subjected to a graded ethanol series and xylene penetration and then embedded in paraffin wax. In other cases, excised uterine tissue was placed in ice-cold PBS (pH 7.4) and opened longitudinally for collection of the myometrium, as previously described (49). The endometrial layer was removed from all samples by gentle scraping with a scalpel blade prior to flash-freezing in liquid nitrogen and storage at Ϫ80°C.…”

“…Northern blot preparation and hybridization were performed as previously described (49). Briefly, RNA (10 g) was prepared, separated on a 1% agarose-formaldehyde-MOPS gel, transferred to a nylon membrane (Hybond-XL nylon membrane, GE Healthcare, Little Chalfont, Buckinghamshire, UK), and stored at Ϫ20 C. Prehybridization of membranes for 1-2 h at 42°C was followed by hybridization with radiolabeled ([ 32 P]dCTP) probes overnight at 42°C.…”

Uterine Smooth MuscleS-Nitrosylproteome in Pregnancy

“…HSP27 has also been shown to be S-nitrosylated under various conditions, leading to the possibility that regulation of HSP27 could be dependent on its nitrosylated state (Shi et al, 2008). HSP27 has also been shown to be highly induced in the myometrium during pregnancy and labor (White et al, 2005). Therefore, we consider HSP27 to be a prime candidate for future studies regarding the possible role of S-nitrosylation as a regulatory mechanism for HSP27 action.…”