Abstract
Slo3 is a pH-sensitive and weakly voltage-sensitive potassium channel that is essential for male fertility in mouse and whose expression is regarded as sperm-specific. These properties have proposed Slo3 as a candidate target for male contraceptive drugs. Nonetheless, the tissue distribution of Slo3 expression has not been rigorously studied yet. Applying computational and RT-PCR approaches, we identified expression of two short Slo3 isoforms in somatic mouse tissues such as brain, kidney and eye. These isoforms, which seem to result of transcription starting sites between exons 20 and 21, have an identical open reading frame, both encoding the terminal 381 amino acids of the cytosolic Slo3 domain. We corroborated the expression of these isoforms in mouse brain and testis by Western-blot. The complete isoform encoding the Slo3 ion channel was uniquely detected in testis, both at transcript and protein level. Although the functional role of the cytosolic Slo3 isoforms remains to be established, we propose that they may have a functional effect by modulating Slo channels trafficking and/or activity. This study confirms that expression of full-length Slo3 is sperm-specific but warns against developing contraceptive drugs targeting the C-terminal tail of Slo3 channels.
Abbreviations
- cDNA:
-
Complementary DNA
- EST:
-
Expressed Sequence Tag
- K+ :
-
Potassium ion
- RCK:
-
Regulator of K+ conductance
- Slo3-CT:
-
Slo3 carboxyl terminal
References
Salkoff L, Butler A, Ferreira G, Santi C, Wei A (2006) High-conductance potassium channels of the SLO family. Nat Rev Neurosci 7:921–931. https://doi.org/10.1038/nrn1992
Xia X, Zhang X, Lingle CJ (2004) Ligand-dependent activation of Slo family channels is defined by interchangeable cytosolic domains. J Neurosci 24:5585–5591. https://doi.org/10.1523/JNEUROSCI.1296-04.2004
Barret JN, Magleby KL, Pallotta B (1982) Properties of single calcium-activated potassium channels in cultured rat muscle. J Physiol 331:211–230
Magleby KL (2003) Gating mechanism of BK (Slo1) channels: so near, yet so far. J Gen Physiol 121:81–96. https://doi.org/10.1085/jgp.20028721
Yuan A, Santi CM, Wei A, Wang ZW, Pollak K, Nonet M et al (2003) The sodium-activated potassium channel is encoded by a member of the Slo gene family. Neuron 37:765–773. https://doi.org/10.1016/S0896-6273(03)00096-5
Bhattacharjee A, Joiner WJ, Wu M, Yang Y, Sigworth FJ, Kaczmarek LK (2003) Slick (Slo2.1), a rapidly-gating sodium-activated potassium channel inhibited by ATP. J Neurosci 23:11681–11691
Zhang X, Zeng X, Xia X, Lingle CJ (2006) pH-regulated Slo3 K + channels: properties of unitary currents. Currents 128:301–315. https://doi.org/10.1085/jgp.200609551
Zhang X, Zeng X, Lingle CJ (2006) Slo3 K + channels: voltage and pH dependence of macroscopic currents. J Gen Physiol 128:317–336. https://doi.org/10.1085/jgp.200609552
Schreiber M, Wei A, Yuan A, Gaut J, Saito M, Salkoff L (1998) Slo3, a novel pH-sensitive K+ Channel from mammalian spermatocytes. J Biol Chem 273:3509–3516
Santi CM, Martínez-lópez P, Luis J, Vega-beltrán D, Butler A, Alisio A et al (2010) The SLO3 sperm-specific potassium channel plays a vital role in male fertility. FEBS Lett 584:1041–1046. https://doi.org/10.1016/j.febslet.2010.02.005
Zeng X-H, Yang C, Kim ST, Lingle CJ, Xia X-M (2011) Deletion of the Slo3 gene abolishes alkalization-activated K+ current in mouse spermatozoa. Proc Natl Acad Sci USA 108:5879–5884. https://doi.org/10.1073/pnas.1100240108
Vicens A, Andrade K, Cortez D, Gutiérrez RM, Treviño C (2016) Pre-mammalian origin of the sperm-specific Slo3 channel. FEBS Open Bio 7:382–390. https://doi.org/10.1002/2211-5463.12186
Maeda N, Kawasaki T, Nakade S, Yokota N, Taguchi T, Kasai M et al (1991) Structural and functional characterization of inositol 1,4,5-trisphosphate receptor channel from mouse cerebellum. J Biol Chem 266:1109–1116
Yuan P, Leonetti MD, Pico AR, Hsiung Y, MacKinnon R (2010) Structure of the human BK channel Ca2+-activation apparatus at 3.0 A resolution. Science 329:182–186. https://doi.org/10.1126/science.1190414
López-González I, Torres-Rodríguez P, Sánchez-Carranza O, Solís-López A, Santi CM, Darszon A et al (2014) Membrane hyperpolarization during human sperm capacitation. Mol Hum Reprod 20:619–629. https://doi.org/10.1093/molehr/gau029
Swensen AM, Bean BP (2003) Ionic mechanisms of burst firing in dissociated Purkinje neurons. J Neurosci 23:9650–9663
Singh H, Li M, Hall L, Chen S, Sukur S, Lu R et al (2016) MaxiK channel interactome reveals its interaction with GABA transporter 3 and heat shock protein 60 in the mammalian brain. Neuroscience 317:76–107. https://doi.org/10.1016/j.neuroscience.2015.12.058
Chen L, Tian L, MacDonald SHF, McClafferty H, Hammond MSL, Huibant JM et al (2005) Functionally diverse complement of large conductance calcium- and voltage-activated potassium channel (BK) α-subunits generated from a single site of splicing. J Biol Chem 280:33599–33609. https://doi.org/10.1074/jbc.M505383200
Zarei MM, Eghbali M, Alioua A, Song M, Knaus H-G, Stefani E et al (2004) An endoplasmic reticulum trafficking signal prevents surface expression of a voltage- and Ca2+-activated K+ channel splice variant. Proc Natl Acad Sci USA 101:10072–10077. https://doi.org/10.1073/pnas.0302919101
Wang SX, Ikeda M, Guggino WB (2003) The cytoplasmic tail of large conductance, voltage- and Ca2+-activated K+ (MaxiK) channel is necessary for its cell surface expression. J Biol Chem 278:2713–2722. https://doi.org/10.1074/jbc.M208411200
Kwon S-H, Guggino WB (2004) Multiple sequences in the C terminus of MaxiK channels are involved in expression, movement to the cell surface, and apical localization. Proc Natl Acad Sci USA 101:15237–15242. https://doi.org/10.1073/pnas.0404877101
Gong XD, Li JCH, Leung GPH, Cheung KH, Wong PYD (2002) A BKCa to Kv switch during spermatogenesis in the rat seminiferous tubules. Biol Reprod 67:46–54. https://doi.org/10.1095/biolreprod67.1.46
Acknowledgements
The authors thank Jose Luis De la Vega, Paulina Torres-Rodríguez, Yoloxóchitl Sánchez, Gabriela Cabeza, Sergio González, Timothy Munsey, and Elizabeth Mata for technical support. We also thank Juan Manuel Hurtado, Roberto Rodríguez, David Castañeda, Arturo Ocádiz and Shirley Ainsworth for computer and library services.
Funding
Dirección General de Asuntos de Personal Académico/Universidad Nacional Autónoma de México; Grant Number: IN202519 to CT; IN215519 to CB; IA200419 to JCC. DCW was supported by a BBSRC PhD studentship.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflict of interest
The co-authors of this manuscript declare that they have no conflict of interests
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Electronic supplementary material
Below is the link to the electronic supplementary material.
Rights and permissions
About this article
Cite this article
Chávez, J.C., Vicens, A., Wrighton, D.C. et al. A cytoplasmic Slo3 isoform is expressed in somatic tissues. Mol Biol Rep 46, 5561–5567 (2019). https://doi.org/10.1007/s11033-019-04943-z
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11033-019-04943-z