Study On The Mechanism Of Male Infertility Caused By Mutations Of DPY19L2 Or KATNAL2

The increasing incidence of infertility has brought severe challenges to the society and family.Men are responsible for about half of all couples’ infertility,and genetic factors are especially important in male infertility.Teratozoospermia is a male infertility phenotype caused by the percentage of normal sperm in semen less than 4%.Globozoospermia is a rare but severe form of teratozoospermia,which is characterized by most or all of the sperm with round head,absence or nonfunction of the acrosomal body,abnormal nuclear membrane and midsegment defects.In our study,we found a case of male infertility in which the normal sperm count ratio on semen examination was 0%and the sperm head was obviously round,so the patient was clinically diagnosed with globozoospermia.To verify whether the patient has genetic defects,we performed CNV sequencing on the whole blood DNA of the patient and found that the homozygous deletion on chromosome 12(12q14.2)was about 180kb(g.6395000164130000).These include complete loss of the DPY19L2.Through the verification of copy number variation in the whole blood DNA of the patient and his family members,homozygous deletions in exons 1,11 and 22 of DPY19L2 were found in the genome of the patient and his mother.After further analysis of the patient’s sperm by papaniclaoll staining and transmission electron microscopy,it was found that there were obvious round defects in the head.These results indicate that the lack of DPY19L2 can lead to typical globozoospermia.Oligo-astheno-teratozoospermia(OAT)is a highly severe complex teratozoospermia,which is characterized by a high degree of abnormal sperm parameters:low sperm count,low motility and abnormal sperm morphology.In this study,whole blood DNA of Patient 1 and Patient 2 from two OAT families were sequenced by Whole exon genome sequencing and Sanger sequencing.Homozygous mutation of KATNAL2 c.328C>T:p.Arg110*was found in the genome of P1,and complex heterozygous mutations of KATNAL2 c.55A>G:p.Lys19Glu and KATNAL2 c.169C>T:p.Arg57Trp were found in the genome of P2.Katnal2 was further knocked out in mice to establish knockout mouse model,and it was found that Katnal2KO/KO mice were infertile,sperm morphology was deformed and sperm number was severely reduced,showing typical OAT phenotype.Our data suggest that KATNAL2 may modulate δ-and ε-tubulin rather than the classical α-and β-tubulin microtubule polymers.At the same time,we also verified again that KATNAL2 can bind with the regulatory protein KATNB1.These results suggest that KATNAL2 may be involved in the pathogenesis of human OAT.