Cumulus-specific genes are transcriptionally silent following somatic cell nuclear transfer in a mouse model

Abstract

This study investigated whether four cumulus-specific genes: follicular stimulating hormone receptor (FSHr), hyaluronan synthase 2 (Has2), prostaglandin synthase 2 (Ptgs2) and steroidogenic acute regulator protein (Star), were correctly reprogrammed to be transcriptionally silent following somatic cell nuclear transfer (SCNT) in a murine model. Cumulus cells of C57xCBA F1 female mouse were injected into enucleated oocytes, followed by activation in 10 micromol/L strontium chloride for 5 h and subsequent in vitro culture up to the blastocyst stage. Expression of cumulus-specific genes in SCNT-derived embryos at 2-cell, 4-cell and day 4.5 blastocyst stages was compared with corresponding in vivo fertilized embryos by real-time PCR. It was demonstrated that immediately after the first cell cycle, SCNT-derived 2-cell stage embryos did not express all four cumulus-specific genes, which continually remained silent at the 4-cell and blastocyst stages. It is therefore concluded that all four cumulus-specific genes were correctly reprogrammed to be silent following nuclear transfer with cumulus donor cells in the mouse model. This would imply that the poor preimplantation developmental competence of SCNT embryos derived from cumulus cells is due to incomplete reprogramming of other embryonic genes, rather than cumulus-specific genes.

Comparative Analysis of Nuclear Transfer Embryo-Derived Mouse Embryonic Stem Cells. Part I: Cellular Characterization

“…A comparison of the two NT methods, using cumulus nuclear donor origin cell lines, revealed very similar results in flow cytometry and ICC experiment that might indicate a smaller distance between the two cell lines [B6D2 CUM NT and B6D2 CUM NT (PEM)] than the same genotype ESC lines (HM1 vs. HM1 NT) (Tong et al, 2007). In one experiment 48 EBs were plated.…”

Somatic cell reprogrammed by oocyte: process and barricade

“…After somatic nuclei were synchronized to M phase, most or even all of the genes are silenced due to impressed intra-environment in the cytoplasm of matured oocytes. For example, in a mouse SCNT study, nucleus of cumulus was transferred into denucleated MII oocyte, most or even all of detected genes were silenced in cloned embryos (Tong et al 2007;Vassena et al 2007). This event facilitates the reprogramming of somatic nuclei and the expression of embryonicspecific genes.…”