Heat shock protein 27 expression is spatially distributed in human placenta and selectively regulated during preeclampsia

Abstract

Placental oxidative stress is a feature of the pregnancy syndrome preeclampsia. Heat shock proteins (HSPs) can be induced in cells as a protective mechanism to cope with cellular stress. We hypothesized that expression of HSP 27, a member of the small HSP family, would change in preeclampsia and that expression would vary in different placental zones. Samples were obtained from eight sites within each placenta: four pieces equally spaced apart were sampled from 0 to 2cm from the cord insertion point and also between 2 and 4cm from the cord insertion point. Non-labor, labor, labor preeclampsia, and non-labor preeclampsia were studied. HSP 27 expression was investigated by Western blot analysis and real-time PCR. HSP 27 was significantly increased in the preeclampsia labor group compared with the control labor group at the 2- to 4-cm site (p=0.02). At this 2- to 4-cm site there was no change in the phosphorylation of HSP 27 at serine 82 or 78, but there was an increase in phosphorylated serine 15 in the preeclampsia labor group compared with the control labor group (p=0.02). No changes were found at the mRNA level between the control and preeclampsia groups. The physiological and pathological significance of these remains to be elucidated, but the results have important implications for how data obtained from studies in placental studies (and other organs) can be influenced by sampling methods.

Keywords: HSP 27; Heat shock protein; Oxidative stress; Placenta; Preeclampsia.