CLIC4 regulates apical exocytosis and renal tube luminogenesis through retromer- and actin-mediated endocytic trafficking.

Chloride intracellular channel 4 (CLIC4) is a mammalian homologue of EXC-4 whose mutation is associated with cystic excretory canals in nematodes. Here we show that CLIC4-null mouse embryos exhibit impaired renal tubulogenesis. In both developing and developed kidneys, CLIC4 is specifically enriched in the proximal tubule epithelial cells, in which CLIC4 is important for luminal delivery, microvillus morphogenesis, and endolysosomal biogenesis. Adult CLIC4-null proximal tubules display aberrant dilation. In MDCK 3D cultures, CLIC4 is expressed on early endosome, recycling endosome and apical transport carriers before reaching its steady-state apical membrane localization in mature lumen. CLIC4 suppression causes impaired apical vesicle coalescence and central lumen formation, a phenotype that can be rescued by Rab8 and Cdc42. Furthermore, we show that retromer- and branched actin-mediated trafficking on early endosome regulates apical delivery during early luminogenesis. CLIC4 selectively modulates retromer-mediated apical transport by negatively regulating the formation of branched actin on early endosomes.

Diagnosis of the gr/gr Y chromosome microdeletion does not help in the treatment of infertile American men.

PURPOSE: The phenotypic effects of the gr/gr partial azoospermia factor c deletion vary geographically and to our knowledge have not been reported in the American population. We evaluated the clinical characteristics of infertile American men with the gr/gr deletion. MATERIALS AND METHODS: We retrospectively reviewed clinical data on 1,410 infertile men tested for the gr/gr deletion. We analyzed sperm concentration and the outcome of microdissection testicular sperm extraction with respect to gr/gr status. RESULTS: We identified 73 men with gr/gr deletions, including 43 of 989 (4.3%) with azoospermia, 18 of 317 (5.7%) with severe oligospermia (less than 5 million sperm per ml), 6 of 61 (9.8%) with oligospermia (5 to less than 20 million sperm per ml) and 6 of 43 (14%) infertile men with normospermia (greater than 20 million sperm per ml). A gr/gr deletion correlated with higher sperm production. The gr/gr deletion rate was higher in men with normospermia than in those with a sperm concentration of less than 20 million and less than 5 million per ml (p = 0.021 and 0.006, respectively). Microdissection testicular sperm extraction was done in 22 azoospermic men with gr/gr deletions and sperm were retrieved in 14 (64%). This retrieval rate was similar to that at our center in men with idiopathic nonobstructive azoospermia (p = 0.13). CONCLUSIONS: Diagnosis of the gr/gr deletion did not predict impaired sperm production in our patient population and did not appear to alter the prognosis for surgical sperm retrieval. Despite the established modulatory impact of the gr/gr deletion on sperm production in some populations at this time the clinical value of testing infertile American men for the gr/gr deletion is not clear.

A decade of experience emphasizes that testing for Y microdeletions is essential in American men with azoospermia and severe oligozoospermia.

OBJECTIVE: To evaluate the benefit of Y microdeletion testing. DESIGN: Retrospective analysis. SETTING: University-based male fertility clinic and genetics laboratory. PATIENT(S): A total of 1,591 men with sperm concentrations less than 5 million sperm/mL. INTERVENTION(S): Semen analysis, Y microdeletion testing, microdissection testicular sperm extraction (TESE). MAIN OUTCOME MEASURE(S): Sperm concentration, incidence and nature of Y microdeletions, microdissection TESE outcome. RESULT(S): We identified 149 microdeletions (9.4%). 10.4% of azoospermic men and 10.1% of men with sperm concentrations >0-1 million sperm/mL harbored microdeletions. Two-thirds of microdeletions in azoospermic men were AZFa, AZFb, AZFb+c, or complete Yq deletions. Virtually all microdeletions in oligozoospermic patients were AZFc deletions. Seven hundred eighteen patients underwent microdissection TESE, including 41 with microdeletions. Microdissection TESE failed in all patients with AZFa, AZFb, AZFb+c, and complete Yq deletions. Sperm were retrieved in 15/21 AZFc deleted patients (71.4%). The presence of an AZFc deletion was associated with increased likelihood of sperm retrieval when compared with the 48.8% retrieval rate in 385 idiopathically azoospermic men who consecutively underwent microdissection TESE at our institution during the study period. Clinical pregnancy was achieved in 10/15 azoospermic AZFc deleted patients for whom sperm were successfully retrieved. CONCLUSION(S): Of azoospermic and severely oligozoospermic American men, 10% harbor Y microdeletions that alter prognosis for surgical sperm retrieval and are vertically transmissible. Y microdeletion testing is essential for genetic and preoperative counseling in these patients.