The control of male fertility by spermatid-specific factors: searching for contraceptive targets from spermatozoon's head to tail.
Male infertility due to abnormal spermatozoa has been reported in both animals and humans, but its pathogenic causes, including genetic abnormalities, remain largely unknown. On the other hand, contraceptive options for men are limited, and a specific, reversible and safe method of male contraception has been a long-standing quest in medicine. Some progress has recently been made in exploring the effects of spermatid-specifical genetic factors in controlling male fertility. A comprehensive search of PubMed for articles and reviews published in English before July 2016 was carried out using the search terms 'spermiogenesis failure', 'globozoospermia', 'spermatid-specific', 'acrosome', 'infertile', 'manchette', 'sperm connecting piece', 'sperm annulus', 'sperm ADAMs', 'flagellar abnormalities', 'sperm motility loss', 'sperm ion exchanger' and 'contraceptive targets'. Importantly, we have opted to focus on articles regarding spermatid-specific factors. Genetic studies to define the structure and physiology of sperm have shown that spermatozoa appear to be one of the most promising contraceptive targets. Here we summarize how these spermatid-specific factors regulate spermiogenesis and categorize them according to their localization and function from spermatid head to tail (e.g., acrosome, manchette, head-tail conjunction, annulus, principal piece of tail). In addition, we emphatically introduce small-molecule contraceptives, such as BRDT and PPP3CC/PPP3R2, which are currently being developed to target spermatogenic-specific proteins. We suggest that blocking the differentiation of haploid germ cells, which rarely affects early spermatogenic cell types and the testicular microenvironment, is a better choice than spermatogenic-specific proteins. The studies described here provide valuable information regarding the genetic and molecular defects causing male mouse infertility to improve our understanding of the importance of spermatid-specific factors in controlling fertility. Although a male contraceptive 'pill' is still many years away, research into the production of new small-molecule contraceptives targeting spermatid-specific proteins is the right avenue.
State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
Su-Ren
SR
Chen
State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.|University of the Chinese Academy of Sciences, Beijing, China.
Aalia
A
Batool
State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.|University of the Chinese Academy of Sciences, Beijing, China.
Yu-Qian
YQ
Wang
State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.|University of the Chinese Academy of Sciences, Beijing, China.
Xiao-Xia
XX
Hao
George Whipple Lab for Cancer Research, University of Rochester Medical Center, Rochester, MN, USA.
Chawn-Shang
CS
Chang
The Mary M. Wohlford Laboratory for Male Contraceptive Research, Population Council, New York, NY, USA.
C Yan
CY
Cheng
State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
Yi-Xun
YX
Liu
D003270:Contraceptive Agents / Q000494:pharmacology*; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D005298:Fertility / Q000502:physiology*; D006801:Humans; D008297:Male; D013077:Sperm Head / Q000187:drug effects / Q000502:physiology*; D013082:Sperm Tail / Q000187:drug effects / Q000502:physiology*; D013087:Spermatids / Q000187:drug effects / Q000378:metabolism*
D003270:Contraceptive Agents