Human sperm rheotaxis: a passive physical process

There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

Abstract

A long-standing question in natural reproduction is how mammalian sperm navigate inside female reproductive tract and finally reach the egg cell, or oocyte. Recently, fluid flow was proposed as a long–range guidance cue for sperm navigation. Coitus induces fluid flow from oviduct to uterus, and sperm align themselves against the flow direction and swim upstream, a phenomenon termed rheotaxis. Whether sperm rheotaxis is a passive process dominated by fluid mechanics, or sperm actively sense and adapt to fluid flow remains controversial. Here we report the first quantitative study of sperm flagellar motion during human sperm rheotaxis and provide direct evidence indicating that sperm rheotaxis is a passive process. Experimental results show that there is no significant difference in flagellar beating amplitude and asymmetry between rheotaxis-turning sperm and those sperm swimming freely in the absence of fluid flow. Additionally, fluorescence image tracking shows no Ca ²⁺ influx during sperm rheotaxis turning, further suggesting there is no active signal transduction during human sperm rheotaxis.

Related collections

Most cited references 40

Record: found
Abstract: found
Article: not found

Progesterone activates the principal Ca2+ channel of human sperm.

Polina V. Lishko, Inna Botchkina, Yuriy Kirichok (2011)

Steroid hormone progesterone released by cumulus cells surrounding the egg is a potent stimulator of human spermatozoa. It attracts spermatozoa towards the egg and helps them penetrate the egg's protective vestments. Progesterone induces Ca(2+) influx into spermatozoa and triggers multiple Ca(2+)-dependent physiological responses essential for successful fertilization, such as sperm hyperactivation, acrosome reaction and chemotaxis towards the egg. As an ovarian hormone, progesterone acts by regulating gene expression through a well-characterized progesterone nuclear receptor. However, the effect of progesterone upon transcriptionally silent spermatozoa remains unexplained and is believed to be mediated by a specialized, non-genomic membrane progesterone receptor. The identity of this non-genomic progesterone receptor and the mechanism by which it causes Ca(2+) entry remain fundamental unresolved questions in human reproduction. Here we elucidate the mechanism of the non-genomic action of progesterone on human spermatozoa by identifying the Ca(2+) channel activated by progesterone. By applying the patch-clamp technique to mature human spermatozoa, we found that nanomolar concentrations of progesterone dramatically potentiate CatSper, a pH-dependent Ca(2+) channel of the sperm flagellum. We demonstrate that human CatSper is synergistically activated by elevation of intracellular pH and extracellular progesterone. Interestingly, human CatSper can be further potentiated by prostaglandins, but apparently through a binding site other than that of progesterone. Because our experimental conditions did not support second messenger signalling, CatSper or a directly associated protein serves as the elusive non-genomic progesterone receptor of sperm. Given that the CatSper-associated progesterone receptor is sperm specific and structurally different from the genomic progesterone receptor, it represents a promising target for the development of a new class of non-hormonal contraceptives.

0 comments Cited 178 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

The CatSper channel mediates progesterone-induced Ca2+ influx in human sperm.

Timo Strünker, Normann Goodwin, Christoph Brenker … (2011)

In the oviduct, cumulus cells that surround the oocyte release progesterone. In human sperm, progesterone stimulates a Ca(2+) increase by a non-genomic mechanism. The Ca(2+) signal has been proposed to control chemotaxis, hyperactivation and acrosomal exocytosis of sperm. However, the underlying signalling mechanism has remained mysterious. Here we show that progesterone activates the sperm-specific, pH-sensitive CatSper Ca(2+) channel. We found that both progesterone and alkaline pH stimulate a rapid Ca(2+) influx with almost no latency, incompatible with a signalling pathway involving metabotropic receptors and second messengers. The Ca(2+) signals evoked by alkaline pH and progesterone are inhibited by the Ca(v) channel blockers NNC 55-0396 and mibefradil. Patch-clamp recordings from sperm reveal an alkaline-activated current carried by mono- and divalent ions that exhibits all the hallmarks of sperm-specific CatSper Ca(2+) channels. Progesterone substantially enhances the CatSper current. The alkaline- and progesterone-activated CatSper current is inhibited by both drugs. Our results resolve a long-standing controversy over the non-genomic progesterone signalling. In human sperm, either the CatSper channel itself or an associated protein serves as the non-genomic progesterone receptor. The identification of CatSper channel blockers will greatly facilitate the study of Ca(2+) signalling in sperm and help to define further the physiological role of progesterone and CatSper.

0 comments Cited 164 times – based on 0 reviews      Review now

Bookmark

Record: found
Abstract: found
Article: not found

Sperm guidance in mammals - an unpaved road to the egg.

Michael Eisenbach, Laura C Giojalas (2006)

Contrary to the prevalent view, there seems to be no competition in the mammalian female genital tract among large numbers of sperm cells that are racing towards the egg. Instead, small numbers of the ejaculated sperm cells enter the Fallopian tube, and these few must be guided to make the remaining long, obstructed way to the egg. Here, we review the mechanisms by which mammalian sperm cells are guided to the egg.

0 comments Cited 162 times – based on 0 reviews      Review now

Bookmark

All references

Author and article information

Journal

Journal ID (nlm-ta): Sci Rep

Journal ID (iso-abbrev): Sci Rep

Title: Scientific Reports

Publisher: Nature Publishing Group

ISSN (Electronic): 2045-2322

Publication date (Electronic): 23 March 2016

Publication date Collection: 2016

Volume: 6

Electronic Location Identifier: 23553

Affiliations

[1 ]Department of Mechanical and Industrial Engineering, University of Toronto , Toronto, ON, Canada

[2 ]LifeQuest Centre for Reproductive Medicine , Toronto, ON, Canada

[3 ]Jiangsu Provincial Key Laboratory of Advanced Robotics & Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University , China

[4 ]Department of Mechatronic Engineering, Shanghai University , China

[5 ]Institute of Biomaterials and Biomedical Engineering, University of Toronto , Toronto, ON, Canada

[6 ]Department of Electrical and Computer Engineering, University of Toronto , Toronto, ON, Canada

Author notes

[a ] srxie@ 123456shu.edu.cn

[b ] sun@ 123456mie.utoronto.ca

[*]

These authors contributed equally to this work.

Article

Publisher Item ID: srep23553

DOI: 10.1038/srep23553

PMC ID: 4804285

PubMed ID: 27005727

SO-VID: d98190a5-2461-4449-a3b1-33539dd5bb6a

License:

This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/

Human sperm rheotaxis: a passive physical process

Read this article at

Abstract

Related collections

Open Library of Humanities Super Collection

Most cited references 40

Progesterone activates the principal Ca2+ channel of human sperm.

The CatSper channel mediates progesterone-induced Ca2+ influx in human sperm.

Sperm guidance in mammals - an unpaved road to the egg.

Author and article information

Journal

Affiliations

Author notes

Article

History

Categories

Comments

Comment on this article

Similar content 584

Cited by 34

Most referenced authors 356