Essential role for SUN5 in anchoring sperm head to the tail
- Institute of Zoology, Chinese Academy of Sciences, China
- The First Affiliated Hospital of Anhui Medical University, China
- Nanjing Medical University, China
- University of Chinese Academy of Sciences, China
Abstract
SUN (Sad1 and UNC84 domain containing)-domain proteins are reported to reside on the nuclear membrane playing distinct roles in nuclear dynamics. SUN5 is a new member of the SUN family, with little knowledge regarding its function. Here, we generated Sun5-/- mice and found that male mice were infertile. Most Sun5-null spermatozoa displayed a globozoospermia-like phenotype but they were actually acephalic spermatozoa. Additional studies revealed that SUN5 was located in the neck of the spermatozoa, anchoring sperm head to the tail, and without functional SUN5 the sperm head to tail coupling apparatus was detached from nucleus during spermatid elongation. Finally, we found that healthy heterozygous offspring could be obtained via intracytoplasmic injection of Sun5-mutated sperm heads for both male mice and patients. Our studies reveal the essential role of SUN5 in anchoring sperm head to the tail and provide a promising way to treat this kind of acephalic spermatozoa-associated male infertility.
Article and author information
Author details
Funding
National Natural Science Foundation of China (31471277)
- Wei Li
National Natural Science Foundation of China (91649202)
- Wei Li
National Key R & D program of China (2016YFA0500901)
- Wei Li
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Ethics
Animal experimentation: All of the animal experiments were performed according to approved institutional animal care and use committee (IACUC) protocols (#08-133) of the Institute of Zoology, Chinese Academy of Sciences. All surgery was performed under sodium pentobarbital anesthesia, and every effort was made to minimize suffering.
Human subjects: Consent authorisation for publication has been obtained from the two couples involved in the research.Written informed consent was provided by the couples who decided to undergo intracytoplasmic sperm injection (ICSI) at our reproductive medicine center. All the research on human subject has got ethical approval given by Biomedical Research Ethics Committee of Anhui Medical University (Reference number: 20140183)
Copyright
© 2017, Shang et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Essential role for SUN5 in anchoring sperm head to the tail
eLife 6:e28199.
https://doi.org/10.7554/eLife.28199
Further reading
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- Developmental Biology
Correct intestinal morphogenesis depends on the early embryonic process of gut rotation, an evolutionarily conserved program in which a straight gut tube elongates and forms into its first loops. However, the gut tube requires guidance to loop in a reproducible manner. The dorsal mesentery (DM) connects the gut tube to the body and directs the lengthening gut into stereotypical loops via left-right (LR) asymmetric cellular and extracellular behavior. The LR asymmetry of the DM also governs blood and lymphatic vessel formation for the digestive tract, which is essential for prenatal organ development and postnatal vital functions including nutrient absorption. Although the genetic LR asymmetry of the DM has been extensively studied, a divider between the left and right DM has yet to be identified. Setting up LR asymmetry for the entire body requires a Lefty1+ midline barrier to separate the two sides of the embryo, without it, embryos have lethal or congenital LR patterning defects. Individual organs including the brain, heart, and gut also have LR asymmetry, and while the consequences of left and right signals mixing are severe or even lethal, organ-specific mechanisms for separating these signals remain poorly understood. Here, we uncover a midline structure composed of a transient double basement membrane, which separates the left and right halves of the embryonic chick DM during the establishment of intestinal and vascular asymmetries. Unlike other basement membranes of the DM, the midline is resistant to disruption by intercalation of Netrin4 (Ntn4). We propose that this atypical midline forms the boundary between left and right sides and functions as a barrier necessary to establish and protect organ asymmetry.
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- Developmental Biology
Numerous reports showed that the epididymis plays key roles in the acquisition of sperm fertilizing ability but its contribution to embryo development remains less understood. Female mice mated with males with simultaneous mutations in Crisp1 and Crisp3 genes exhibited normal in vivo fertilization but impaired embryo development. In this work, we found that this phenotype was not due to delayed fertilization, and it was observed in eggs fertilized by epididymal sperm either in vivo or in vitro. Of note, eggs fertilized in vitro by mutant sperm displayed impaired meiotic resumption unrelated to Ca2+ oscillations defects during egg activation, supporting potential sperm DNA defects. Interestingly, cauda but not caput epididymal mutant sperm exhibited increased DNA fragmentation, revealing that DNA integrity defects appear during epididymal transit. Moreover, exposing control sperm to mutant epididymal fluid or to Ca2+-supplemented control fluid significantly increased DNA fragmentation. This, together with the higher intracellular Ca2+ levels detected in mutant sperm, supports a dysregulation in Ca2+ homeostasis within the epididymis and sperm as the main factor responsible for embryo development failure. These findings highlight the contribution of the epididymis beyond fertilization and identify CRISP1 and CRISP3 as novel factors essential for sperm DNA integrity and early embryo development.
