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Published on: February 6, 2018
Lyzl4, a novel mouse sperm-related protein, is involved in fertilization
Ruilin Sun1, Ruling Shen, Jun Li
1Laboratory of Molecular Cell Biology, Institute of Biochemistry and Cell biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
Abstract:
The role of Chicken-type (c-type) lysozyme, a prototype lysozyme, in immunity has been characterized in many organisms. In this study, we cloned a novel c-type lysozyme-like gene, Lyzl4, which was located on mouse chromosome 9F4 and encoded 145 amino acids with a putative signal peptide and a protease cleavage site. The mature recombinant Lyzl4 protein expressed in yeast did not show the bacteriolytic activity. Sequence alignment analysis demonstrated that 3 of the 20 invariant residues in c-type lysozymes were changed in Lyzl4. One of the 'changed' amino acids (D52G) is located in the catalytic domain. Lyzl4 mRNA was selectively expressed in testis and epididymis in adult mice, with varying expression level across different developmental stages. High level of Lyzl4 protein was found on the spermatozoa of acrosomal region and principal piece of tail. Immuno-neutralization of Lyzl4 protein in spermatozoa with its specific antibody significantly decreased in vitro fertilization percentage in a dose-dependent manner, suggesting that Lyzl4 might be important for fertilization.
Insights
A novel gene, Lyzl4, was identified in mice. Lyzl4 protein is crucial for sperm function and significantly impacts in vitro fertilization success.
Area of Science:
- Immunology
- Reproductive Biology
- Molecular Biology
Background:
- Chicken-type (c-type) lysozyme plays a key role in immunity across various species.
- The specific functions of lysozyme-like proteins, such as Lyzl4, are not fully understood.
Purpose of the Study:
- To clone and characterize a novel c-type lysozyme-like gene, Lyzl4, in mice.
- To investigate the expression pattern and potential function of Lyzl4 in mammalian reproduction.
Main Methods:
- Cloning of the Lyzl4 gene from mouse chromosome 9F4.
- Expression of recombinant Lyzl4 protein in yeast and assessment of bacteriolytic activity.
- Sequence alignment analysis to compare Lyzl4 with known c-type lysozymes.
- Analysis of Lyzl4 mRNA expression in adult mouse tissues and developmental stages.
- Immunohistochemical localization of Lyzl4 protein on spermatozoa.
- In vitro fertilization assays using Lyzl4-specific antibodies for immuno-neutralization.
Main Results:
- Lyzl4 encodes a 145-amino acid protein with a signal peptide and protease cleavage site.
- Recombinant Lyzl4 protein lacks bacteriolytic activity, differing from typical c-type lysozymes due to altered invariant residues.
- Lyzl4 mRNA is selectively expressed in the testis and epididymis.
- Lyzl4 protein is highly localized on mouse spermatozoa, particularly in the acrosomal region and principal piece of the tail.
- Immuno-neutralization of Lyzl4 significantly reduces in vitro fertilization rates in a dose-dependent manner.
Conclusions:
- Lyzl4 is a divergent c-type lysozyme-like protein with a distinct function.
- Lyzl4 plays a significant role in mammalian fertilization, likely by influencing sperm function.
- Further research into Lyzl4's specific mechanism in fertilization is warranted.
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