title: Genome-wide promoter methylation profile of human testis and epididymis: identified from cell-free seminal DNA.
abstract: BACKGROUND
  DNA methylation analysis is useful for investigation of male fertility in mammals, whereas the reliance on tissues limits the research on human. We have previously found the presence of high concentration of cell-free seminal DNA (cfsDNA) in human semen. We proposed that some testis and epididymis-specific methylated promoters could be detected in human cfsDNA, and thus hold promise as noninvasive epigenetic biomarkers for male infertility, of which most cases are caused by defects in testicular sperm production or epididymal sperm maturation.
  
  
  RESULTS
  The ejaculate of successfully vasectomized men does not contain any secretion from testis and epididymis. Here we compared genome-wide promoter methylation profiles in cfsDNA between health donors and post-vasectomy men. Promoters of 367 testis and epididymis-specific hypomethylated genes and 134 hypermethylated genes were identified. Subsequent validation by Methyl-DNA immunoprecipitation and MethyLight analysis confirmed the result of promoter microarray. Gene Ontology analysis revealed many genes involved in male reproduction.
  
  
  CONCLUSIONS
  We detected the testis and epididymis-specific methylated promoters in human cfsDNA, which may be used for noninvasive epigenetic biomarkers for the study and diagnosis of male infertility.
authors.affiliation: Family Planning Research Institute/Center of Reproductive Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
authors.forename: Chunlin
authors.initials: C
authors.lastname: Wu
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Ding
authors.forename: Honggang
authors.initials: H
authors.lastname: Li
authors.forename: Changhong
authors.initials: C
authors.lastname: Zhu
authors.forename: Chengliang
authors.initials: C
authors.lastname: Xiong
mesh_terms: D015415:Biomarkers / Q000032:analysis; D004247:DNA / Q000378:metabolism; D019175:DNA Methylation; D004822:Epididymis / Q000378:metabolism*; D044127:Epigenesis, Genetic; D055106:Genome-Wide Association Study; D006801:Humans; D007248:Infertility, Male / Q000175:diagnosis*; D008297:Male; D058977:Molecular Sequence Annotation; D011401:Promoter Regions, Genetic / Q000235:genetics / Q000502:physiology*; D012661:Semen / Q000737:chemistry*; D013079:Sperm Maturation; D013737:Testis / Q000378:metabolism*; D014659:Vasectomy
chemical_list: D015415:Biomarkers; D004247:DNA