Mechanism Of Male Infertility And Abnormal Sperm Flagella Caused By PKD1 Variants

Objective: Autosomal dominant polycystic kidney disease(ADPKD)is one of the Mendlian disorders characterized by progressive bilateral renal cysts,with estimated prevalence of one in 1000 individuals.The pathogenic genes of ADPKD are PKD1 and PKD2,which encode the polycystin Polycystin-1(PC1)and Polycystin-2(PC2),respectively.In this study,we aim to genetically diagnose patients with PKD,analyze assist reproductive outcomes of preimplantation genetic testing,and explore the relationship between ADPKD and male infertility.Methods: Whole genome or exome sequencing was applied for genetic diagnosis of suspected patients and several patients resorted to preimplantation genetic testing.Semen samples from all patients and age-matched controls were obtained by masturbation.Sperm morphology was detected by sperm immunostaining and transmission electron microscopy and sperm motility were assessed by ComputerAssisted Sperm Analysis(CASA)system.In vitro,cell functions,including cell proliferation and cilia differentiation,and Hippo signaling pathway were observed and analyzed in Pkd1-depleted kidney tubule cells.Results: There was no significant difference in fertilization rate,cleavage rate,effective embryo rate and excellent embryo rate between PGT cycles of ADPKD patients and PGT cycles of DMD carriers,but a early abortion was prone to occur in the ADPKD group.Compared to controls,ADPKD patients had poorer sperm parameters and were all suffered from mild to severe asthenozoospermia,oligozoospermia or teratozoospermia.In sperm morphology,the sperm flagella of the ADPKD group were significantly coiled.Moreover,flagella lengths of the ADPKD group were shorter than that of normal control group.Transmission electron microscopy(TEM)observed defects of sperm ultrastructure in ADPKD group,including absent central microtubules,irregular peripheral doublets and disorganizations of outer dense fibers.Furthermore,the expression of acetylated α-tubulin in sperms from ADPKD was remarkably reduced.In vitro,decreased acetylated α-tubulin was also observed in Pkd1-depleted cells.Absence of PC1 also induced reduction of MST1 and LATS1,the core kinases of Hippo pathway.The reduced MST1 and LATS1 led to a decrease of phospho-YAP/TAZ,so that YAP/TAZ were prone to accumulate in nuclei increasing the expression of its transcriptional target,AURKA,which is a cilia-disassembly protein.Conclutions: Our results suggested that male ADPKD patients showed poor sperm parameters and typical microtubule structure defects in sperm flagella.In Pkd1-depleted kidney tubule cells,reduced Pkd1,combined with dysregulated Hippo pathway-YAP/TAZ-AURKA axis,enhanced the deacetylation process of acetylated α-tubulin promoting the disassembly of cell cilia,which led to the defects and abnormalities of cilia.