Lhx8 (LIM homeobox 8) gene encodes a LIM homeodomain transcriptional regulator that is preferentially expressed in germ cells and critical for mammalian folliculogenesis. However, Lhx8 DNA binding sequences are not characterized yet. We aimed to identify and characterize a cis-acting sequence of germ-cell specific transcriptional factor, Lhx8. To identify Lhx8 DNA binding element, Cyclic Amplification of Sequence Target (CAST) Analysis was performed. Electrophoretic Mobility Shift Assay (EMSA) was processed for the binding specificity of Lhx8. Luciferase assay was for the transcriptional activity of Lhx8 through identified DNA binding site. We identified a putative cis-acting sequence, TGATTG as Lhx8 DNA binding element (LBE). In addition, Lhx8 binds to the LBE with high affinity and augments transcriptional activity of luciferase reporter driven by artificial promoter containing the Lhx8 binding element. These findings indicate that Lhx8 directly regulates the transcription of genes containing Lhx8 binding element in oocytes during early folliculogenesis.

SOHLH2 is a novel germ cell-specific transcription factor that is crucial for folliculogenesis in the ovary and spermatogenesis in the testis. SOHLH2 represents a candidate gene for infertility with premature ovarian failure. We analyzed whether mutations in the SOHLH2 gene in 98 Korean women with premature ovarian failure. The sequence analysis identified six novel SNPs (c.431-41G>C, c.656A>T, c.1000+27C>T, c.1000+33G>T, c1258-106G>A, and c.2094+ 11T>C) from Korean patients with premature ovarian failure. The c.656A>T found in exon 7 results in change of an amino acid, tyrosine to phenylalanine. Functional mutations in SOHLH2 gene are rare in Korean women with premature ovarian failure.