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Oocyte specific transcription factor, Lhx8 regulates the target genes through its specific DNA binding element
- 언어ENG
- URLhttps://db.koreascholar.com/Article/Detail/354637
Lhx8 is a member of the LIM-homeobox transcription factor family expressed in the mouse ovary. We discovered that Lhx8 knockout females lose oocytes within 7 days after birth. Lhx8–/–ovaries fail to maintain the primordial follicles and growing follicles. Lhx8–/–ovaries misexpress numerous oocyte-specific genes such as H1foo and Nlrp14. The molecular mechanism of there gulation of Lhx8 in the oocyte has not been described. We examined to characterize Lhx8 DNA binding elements and to identify its direct target genes in the oocyte. CAST was performed using glutathione transferase Lhx8 homeodomain fusion protein (GST-LHX8HD). A 15-bp random sequence flanked by 20-bp of fixed sequences were incubated with purified GST-LHX8HD protein. Unbound DNA was washed with binding reaction buffer. Bound DNA was eluted and re-amplified by PCR for the next round of CAST. Final PCR products were cloned and sequenced to derive consensus binding sequence. EMSA was performed using 32P-labeled oligomers. Binding reactions were conducted by incubating 32P-labeled probes with purified protein. Dual luciferase assays were carried out with extracts of total HEK293 cell which was transfected by the pGL4-promoter vector containing three artificial repeats of LBE(3xLBE-Luc) and overexpression vector carrying the Lhx8 homeodomain as recommended by Promega. We identified several cis-acting sites, TGATTG as Lhx8 DNA binding elements (LBE) using a library of randomly generated oligonucleotides by CAST. EMSA reslut shows that Lhx8 preferentially binds to the oligomer including Lhx8 binding element (TGATTG) with high affinity. In addition, we found that the relative luciferase activity of reporter construct containing three copies of TGATTG was increased by 2.3-fold with Lhx8 overexpression. These results suggest that Lhx8 preferentially binds Lhx8 DNA binding element, TGATTG, and can transactivate reporter genes through the LBE. The transcription of Lhx8 target gene in oocytes directly might be regulated by its during early folliculogenesis.
