抄録
One up-regulated protein in cloned mouse placentae was identified as tissue inhibitor of metalloproteinase-2 (TIMP-2); this protein is involved in extracellular matrix degradation and tissue remodeling. Also, PBEF (Pre-b cell colony enhancing factor 1) was down-regulated in cloned placentae; this protein inhibits apoptosis and induces spontaneous labor. Herein, we used Western blotting to analyze the expression levels of TIMP-2 and PBEF in the cloned placentae derived from cumulus cells and TSA-treated cells; in the placentae from ICSI (Intracytoplasmic sperm injection); and in normal placentae developing after natural mating. TIMP-2 was up-regulated in cloned compared tonormal placenta. Placentae derived from cumulus cells and TSA-treated cells showed the elevated level of TIMP-2 compared with normal placent and ICSI. Notably, the extent of TIMP-2 expression and theplacental weight of cloned mouse concepti were positively associated. PBEF was significantly down-regulated in cloned and ICSI placentae compared to those produced via natural mating. Sodium bisulfite sequencing did not reveal any differences in DNA methylation in cloned placentae versus normal controls, but ChIP assays revealed that H3-K9/K14 acetylation at the TIMP-2 locus was higher in cloned placentae versus normal controls, whereas acetylation of the PBEF promoter was lower in cloned placentae and ICSI placenta versus normal controls. These results suggest that TIMP-2 and PBEF are involved in abnormal hypertrophic placental development in mouse. Thus, cloned placentae appear to suffer from failure of histone modification reprogramming in these (and potentially other)developmentally important genes, leading to aberrant expression of their protein products.
