Expression of ciliated bronchial epithelium 1 during human spermatogenesis

Objective To define the precise cellular localization of ciliated bronchial epithelium 1 (CBE1) in the human testis and test its relationship to impaired spermatogenesis. Design Gene expression analysis, and histologic and immunohistochemical evaluation. Setting University research laboratories and andrologic outpatient clinic. Patient(s) Forty-three human testicular biopsies: 12 biopsies showing normal spermatogenesis (NSP), 8 with maturation arrest at level of spermatocytes (STA), 8 with maturation arrest at level of spermatids (SDA), 4 with scattered elongating spermatids, and 12 with Sertoli cell-only syndrome, with an additional 5 semen samples from healthy donors. Intervention(s) None. Main Outcome Measure(s) Evaluation of CBE1 expression in normal as well as impaired spermatogenesis on mRNA (quantitative reverse-transcription polymerase chain reaction and in situ hybridization) and protein level (immunohistochemistry, Western blot analysis). Result(s) In normal spermatogenesis, CBE1 mRNA was expressed in late pachytene spermatocytes, and the protein was localized within the flagellum of elongating spermatids from stage V up to the spermiation in stage II. Immunoelectron microscopy showed CBE1 clearly associated with microtubules at the manchette, the head-tail coupling apparatus, and the flagellum, but the protein was absent in spermatozoa. Compared with normal spermatogenesis, CBE1 mRNA was statistically significantly reduced in samples with a maturation arrest at the level of round spermatids and primary spermatocytes, and was absent in samples showing Sertoli cell-only syndrome. CBE1 protein was completely missing in SDA samples showing few elongating spermatids. Conclusion(s) Our data strongly suggest an influence of CBE1 in ciliogenesis in spermatids due to the localization at the microtubules of the elongating spermatids, indicating a role in the intramanchette and/or intraflagellar transport mechanism. The absence of CBE1 in spermatozoa suggests that CBE1 is important for the spermatid development but not for the maintenance of mature spermatozoa as a component of the flagellum.