Reproduction Abstracts

Introduction: Deleted in azoospermia-like (DAZL ) is an RNA-binding protein essential for germ cell entry into meiosis and later stages of germ cell maturation, and its absence is associated with infertility in vertebrates. Efforts to identify in vivo mRNA targets of DAZL have mainly been restricted to mouse, thus human-specific investigations are required.

Materials and methods: RT-qPCR and western blotting were used to profile DAZL isoform expression in human fetal ovary and testis. Human DAZL protein was immunoprecipitated from 17-week ovarian lysate; bound RNAs were analysed by RT-qPCR.

Results and discussion: Two isoforms of DAZL differing in the 5′UTR and N-terminus coding sequence are reported in NCBI. mRNA for DAZL isoform 2 (the original isoform) was predominant over DAZL isoform 1 in fetal gonads of both sexes, and its expression increased across gestation in the ovary but not testis. DAZL isoform 1 protein was detected in both fetal gonads, whilst isoform 2 was absent in the testis. RT-qPCR of DAZL-immunoprecipitated ovarian RNA demonstrated enrichment of murine DAZL targets VASA, TEX14, and SOX17.

We have identified the expression of a DAZL isoform not previously reported in human gonads. The selective expression of DAZL isoform 2 in fetal ovary may suggest it is this isoform that is involved in meiotic control of ovarian gametogenesis. Specific functional roles of DAZL isoform 1 remain unknown. Preliminary data confirm VASA, TEX14, and SOX17 mRNAs as targets of human DAZL, as in mouse.