Primary,Study On The Role Of GGNBP1 During Spermatogenesis

Multiple morphological abnormalities of the flagella(MMAF)is a polymorphic abnormal sperm syndrome which was officially named in 2014,MMAF is mainly manifested in the abnormalities of sperm flagella,such as bending,fracture,shorten and so on.It has been reported that the defects of AKAP4?CCDC39?DNAH1?CEP 135?CFAP43 and CFAP44 are associated with MMAF,but the pathogenesis of a lot of MMAF patients are still unknown.In mouse,we found that there are some correlations between gametogenetin-binding protein 1(GGNBP1)and spermatogenesis.GGNBP1 is a testis specific gene,and it is located on the inner membrane of the mitochondria,but its functional role in spermatogenesis remain unknown.Therefore,we constructed a knockout mouse of GGNBP1 by CRISPR/Cas9 technology.A deletion of 46 base pair(bp)in GGNBP1 gene was detected in their offspring.And the GGNBP1 knockout mice show some abnormalities during spermatoogenesis.About 30%seminiferous tubules had vacuoles in the seminiferous tubules,and the cell loss in the lumen of GGNBP1 knockout mouse maybe caused by apoptosis,because the TUNEL stanning was positive on spermatogenic cells,even on the elongated sperms.While in the epididymis,the sperm number was decreased,and their motility was decreased,either.In addition,various deformed sperm were found,such as malformed head,flexed tail,separation between sperm and head,and the proportion of malformed sperms increased.Further studies demonstrated that the abnormality of sperm occurred in 8th stage during spermatogenesis,the density of sperm head was decreased,and the acrosome was detached from the nucleus after GGNBP1 was knocked out in the testis.Further study with the TEM analysis,we found that acrosome was abnormal and fractured,and the elongated sperm head was bent and more unremoved cytoplasm still could be detected in GGNBP1 knockout mouse.So,we concluded that the phenotype of GGNBP1 knockout mouse is similar to the MMAF syndrome.Then,we used GGNBP1 knockout mouse at 3 month,and found that the morphology of the seminiferous tubules in the testis of GGNBP1 knockout mice had no more obvious change compared with wild type mouse,indicating that GGNBP1 have a little affect at the early stage of the spermatogenesis,but the later process is seriously affected,more abnormal sperm was observed,especially the tail.From these data,we knew that GGNBP1 mainly act in the later stage of the spermatogenesis process,especially in the shape stage.In summary,we demonstrated that there was a close relationship between the loss of function GGNBP1 and the development of MMAF,and our study provided a potential etiology of MMAF.