Publications by authors named "Sandra Yassine"
Article Synopsis
- - In mammals, sperm-oocyte fusion triggers calcium (Ca(2+)) oscillations that are essential for oocyte activation, a crucial step for embryo development, primarily mediated by sperm-specific proteins like PLCZ1 and potentially PAWP.
- - A study of two infertile brothers revealed a harmful mutation in PLCZ1 that disrupted its function in sperm, leading to fertilization failure by causing abnormal Ca(2+) activity and early embryonic development issues.
- - The findings underscore that the absence of PLCZ1 is enough to impede oocyte activation, highlighting its critical role in fertilization, and indicate opportunities for further research on the protein’s structure and function relating to fertility.
Article Synopsis
- The study investigates the roles of different phospholipase A2 (PLA2) isoforms in the sperm acrosome reaction (AR), particularly in spontaneous and progesterone (P4)-induced reactions.
- It finds that iPLA2β is essential for spontaneous AR, while both iPLA2β and secreted group X PLA2 contribute to P4-induced AR; cytosolic PLA2α is not necessary for either.
- Additionally, sperm utilize distinct PLA2 pathways depending on the timing and concentration of P4, with lower concentrations showing different reliance on iPLA2β and group X PLA2 during early and late stages of the reaction.
Article Synopsis
- The acrosome is crucial for sperm function, and defects in its development can lead to globozoospermia, a serious form of male infertility.
- Research has identified the DPY19L2 gene as a significant factor in this process, affecting how the acrosome attaches to the nuclear envelope.
- The study further explores the role of the Sun5 protein in this attachment, revealing that it does not interact with the acrosome directly and suggesting that the acrosome's attachment mechanism may not rely on SUN complexes as previously thought.
Article Synopsis
- The DPY19L2 gene has been identified as a key cause of globozoospermia, contributing to 70% of cases, and knockout mice serve as effective models for studying its biological effects.
- Recent findings indicate that PLCζ, crucial for initiating Ca(2+) oscillations during fertilization, is absent or significantly reduced in sperm from individuals with DPY19L2-related globozoospermia, leading to their poor fertilization capacity.
- The research also reveals the localization of PLCζ in normal human sperm, emphasizing its role in oocyte activation, while defects in sperm chromatin compaction in DPY19L2 knockout mice are linked to sperm DNA damage, further explaining infertility challenges.
We recently identified the DPY19L2 gene as the main genetic cause of human globozoospermia. Non-genetically characterized cases of globozoospermia were associated with DNA alterations, suggesting that DPY19L2-dependent globozoospermia may be associated with poor DNA quality. However the origins of such defects have not yet been characterized and the consequences on the quality of embryos generated with globozoospermic sperm remain to be determined.
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- * In a study of 20 North African men facing primary infertility due to sperm motility issues, 28% had a specific genetic mutation in the DNAH1 gene, which is important for sperm flagella function.
- * Testing confirmed that the DNAH1 mutation led to the absence of both the mRNA and protein in one subject, causing significant structural defects in sperm, while infertility was the only notable symptom, indicating a less critical role of DNAH1 in other ciliated cells.
Article Synopsis
- - The processes of sperm-head elongation and acrosome formation during the final stages of spermatogenesis are crucial for the development of functional sperm capable of fertilization.
- - A study identified the gene DPY19L2 as a key factor in type I globozoospermia, a form of male infertility, linking its deletion to the production of abnormal sperm with round heads and no acrosomes.
- - Using knockout mice, researchers found that the Dpy19l2 protein is specifically localized in the inner nuclear membrane and is essential for the structural stability of sperm, facilitating proper nuclear and acrosome attachment, which is vital for sperm development.