Failure of spermatogenesis in mouse lines deficient in the Na+-K+-2Cl– cotransporter

Abstract

The Na(+)-K(+)-2Cl(-) cotransporter (NKCC1) carries 1 molecule of Na(+) and K(+) along with 2 molecules of Cl(-) across the cell membrane. It is expressed in a broad spectrum of tissues and has been implicated in cell volume regulation and in ion transport by secretory epithelial tissue. However, the specific contribution of NKCC1 to the physiology of the various organ systems is largely undefined. We have generated mouse lines carrying either of 2 mutant alleles of the Slc12a2 gene, which encodes this cotransporter: a null allele and a mutation that results in deletion of 72 amino acids of the cytoplasmic domain. Both NKCC1-deficient mouse lines show behavioral abnormalities characteristic of mice with inner ear defects. Male NKCC1-deficient mice are infertile because of defective spermatogenesis, as shown by the absence of spermatozoa in histological sections of their epididymides and the small number of spermatids in their testes. Consistent with this observation, we show that Slc12a2 is expressed in Sertoli cells, pachytene spermatocytes, and round spermatids isolated from wild-type animals. Our results indicate a critical role for NKCC1-mediated ion transport in spermatogenesis and suggest that the cytoplasmic domain of NKCC1 is essential in the normal functioning of this protein.

NKCC1-Dependent GABAergic Excitation Drives Synaptic Network Maturation during Early Hippocampal Development

“…Ϫ/Ϫ and Ae3 Ϫ/Ϫ mice used in this study has been described previously (Pace et al, 2000;Hentschke et al, 2006). Studies were performed on a C57BL/6 (NKCC1) or a mixed 129-SVJ/ C57BL/6 (AE3) background, respectively, using littermates as controls.…”

“…We used Nkcc1-knock-out (KO) (Nkcc1 Ϫ/Ϫ ) mice (Pace et al, 2000) to examine the role of NKCC1 in the regulation of [Cl Ϫ ] i and the developing neuronal network in the immature hippocampus. Diminished GABAergic excitation in Nkcc1 Ϫ/Ϫ mice resulted in reduced and less correlated spontaneous network activity.…”

CIB1 Is Essential for Mouse Spermatogenesis

“…Although genes expressed only in the testis such as Gapdhs (glyceraldehyde 3-phosphate dehydrogenase-S) (22) and genes that are more widely expressed such as Cdk2 (cyclin-dependent kinase 2) (32) have been implicated in spermatogenesis, the regulation of this process is not fully understood due to the complex involvement and regulation of multiple gene products (21,46). Interestingly, several genes not previously implicated in spermatogenesis were found to be essential for male mouse reproduction when specific knockout mice were generated, including Ppp1cc, which encodes the protein phosphatase 1c␥ subunit (PP1c␥) (41), and NKcc2, which encodes Na ϩ -K ϩ -2Cl Ϫ cotransporter (34). Here, we describe another gene, Cib1, which is essential for male mouse fertility.…”

Cl− Channels and Transporters in Sperm Physiology

“…It is worth noting that the ZP-induced AR depended on the presence of the three ions and was inhibited at much lower concentrations of bumetanide, suggesting that NKCC might have a role in the preparation of the sperm for the physiologically induced AR. NKCC1 transcripts were detected in spermatids, and male mouse null mutants of this protein have defects in spermatogenesis and are infertile (Pace et al 2000 ). Thiazide, a specifi c NCC inhibitor, did not interfere with capacitation-associated processes.…”