Abstract
As one of the non-classical major histocompatibility complex(MHC)-1 antigens, Human Leukocyte Antigen G (HLA-G), has been suggested as a prognostic marker to identify the embryo developmental potential. In the present study, we investigated the potential roles of HLA-G in human spermatogenesis and early embryonic development. Quantitative real-time PCR analysis revealed that HLA-G's expression was increased with increased Johnsen score in testicular tissues. There was no significant difference in HLA-G mRNA expression between testicular tissues with Johnsen score of 8–9 and normal sperm from ejaculated semen. HLA-G mRNA expression was detected in human zygotes, embryos and blastocysts but not in unfertilized oocytes. In testicular tissues where sperm was obtained by testicular sperm extraction (Johnsen score was 8 to 9), there were no correlations between HLA-G mRNA expression and fertilization, cleavage and high-quality embryo rates. At 48–72 h post-fertilization, HLA-G expression was higher in fast growing embryos. HLA-G specific siRNA injection into zygotes not only slowed down embryonic cleavage rate at 48 h post-fertilization, but also down-regulated the expression of embryo metabolism related gene (SLC2A1) and cell cycle-regulated gene (CCND2). Taken together, our findings suggested that HLA-G plays significant roles in human spermatogenesis and early embryonic development.
Highlights
Human leukocyte antigen G (HLA-G) is a non-classical major histocompatibility complex (MHC) class I antigen characterized by specific tissue distribution and gene variation
Except for testicular tissues from azoospermia patients, two testicular tissues retrieved from normospermic patients due to difficulty in semen collection on the day of oocyte retrieval were examined for HLA-G mRNA expression (Fig. 2A and B)
Our results demonstrated that HLA-G mRNA levels in testicular tissues with spermatocytes were significantly higher than those with only sertoli cells and/or spermatogonia
Summary
Human leukocyte antigen G (HLA-G) is a non-classical major histocompatibility complex (MHC) class I antigen characterized by specific tissue distribution and gene variation. HLA-G proteins can be expressed as seven distinct isoforms, by means of an alternative splicing from a single primary transcript. Membrane-bound HLA-G can be modified into soluble isoforms [1,2]. As an important immunomodulatory molecule, HLA-G inhibits cytotoxic activity of T cell, natural killer (NK) cell lysis and cell proliferation. HLA-G regulates the maturation, migration, transportation of dendritic cells and cross talk between T cell and NK cell. The functions of HLA-G are fulfilled by inhibitory receptors expressed on the cell surface, such as ILT-2 (immunoglobulin-like transcript2/LILRB1), ILT-4 (Ig-like transcript-4/LILRB2) and KIR2DL4 (killer inhibitory receptor) [4,5,6]. Except for its immune function, the non-immune function of HLA-G in reproduction has been discovered in recent years [2,7,8,9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
