Deficient LRRC8A-dependent volume-regulated anion channel activity is associated with male infertility in mice
Jianqiang Bao, … , Qinghua Shi, Fernando Benavides
Jianqiang Bao, … , Qinghua Shi, Fernando Benavides
Published August 23, 2018
Citation Information: JCI Insight. 2018;3(16):e99767. https://doi.org/10.1172/jci.insight.99767.
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Research Article Genetics Reproductive biology

Deficient LRRC8A-dependent volume-regulated anion channel activity is associated with male infertility in mice

Abstract

Ion channel-controlled cell volume regulation is of fundamental significance to the physiological function of sperm. In addition to volume regulation, LRRC8A-dependent volume-regulated anion channel (VRAC) activity is involved in cell cycle progression, insulin signaling, and cisplatin resistance. Nevertheless, the contribution of LRRC8A and its dependent VRAC activity in the germ cell lineage remain unknown. By utilizing a spontaneous Lrrc8a mouse mutation (c.1325delTG, p.F443*) and genetically engineered mouse models, we demonstrate that LRRC8A-dependent VRAC activity is essential for male germ cell development and fertility. Lrrc8a-null male germ cells undergo progressive degeneration independent of the apoptotic pathway during postnatal testicular development. Lrrc8a-deficient mouse sperm exhibit multiple morphological abnormalities of the flagella (MMAF), a feature commonly observed in the sperm of infertile human patients. Importantly, we identified a human patient with a rare LRRC8A hypomorphic mutation (c.1634G>A, p.Arg545His) possibly linked to Sertoli cell–only syndrome (SCOS), a male sterility disorder characterized by the loss of germ cells. Thus, LRRC8A is a critical factor required for germ cell development and volume regulation in the mouse, and it might serve as a novel diagnostic and therapeutic target for SCOS patients.

Authors

Jianqiang Bao, Carlos J. Perez, Jeesun Kim, Huan Zhang, Caitlin J. Murphy, Tewfik Hamidi, Jean Jaubert, Craig D. Platt, Janet Chou, Meichun Deng, Meng-Hua Zhou, Yuying Huang, Héctor Gaitán-Peñas, Jean-Louis Guénet, Kevin Lin, Yue Lu, Taiping Chen, Mark T. Bedford, Sharon Y.R. Dent, John H. Richburg, Raúl Estévez, Hui-Lin Pan, Raif S. Geha, Qinghua Shi, Fernando Benavides

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Figure 4

Diminished activity of VRAC in germ cells of Lrrc8aF443*/F443* males.

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Diminished activity of VRAC in germ cells of Lrrc8aF443*/F443* males. (A...
(A and B) Changes in current densities over time recorded at +80 mV (A) or −80 mV (B) in spermatocytes obtained from WT controls and Lrrc8aF443*/F443* mice after switching to a hypotonic solution (n = 9 in each group). Data represent mean ± SEM. (C) Representative current traces in spermatocytes from WT (upper panel) and Lrrc8aF443*/F443* testis (lower panel). Inset, voltage step protocol. (D) Quantification of current densities elicited at +140 mV in spermatocytes from WT and Lrrc8aF443*/F443* mice (n = 13 in each group). Data are shown as mean ± SEM. *P < 0.001 (Student’s t test). (E) Original current traces recorded in different extracellular Cl– concentrations in spermatocytes from WT (left panel) and Lrrc8aF443*/F443* (right panel) testes. The voltage was changed from –80 mV to +80 mV with 10 mV increments, each lasting 200 ms with an interval of 1 second. The holding potential was –70 mV. Dashed lines indicate zero current. (F) Current-voltage (I-V) relationships of maximally activated currents. The I-V relationship shows a reversal potential near 0 at equimolar intra- and extracellular Cl– of 100 mM. There is a progressive shift to more positive potentials with reduced extracellular Cl– from 100 mM to 50 mM and then to 4 mM in spermatocytes from WT testes (n = 10). This shift is absent in spermatocytes from Lrrc8aF443*/F443* testis (MUT, n = 11). Data are presented as mean ± SEM.