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Phosphorylation of Shc proteins in human sperm in response to capacitation and progesterone treatment
C Morte1, A Iborra, P Martínez
1Unitat d'Immunologia, Institut de Biologia Fonamental, Universitat Autònoma de Barcelona, Bellaterra, Spain.
Abstract:
Several authors have demonstrated the involvement of tyrosine kinases during sperm capacitation and acrosome reaction. Shc proteins (p46Shc, p52Shc, and p66Shc) are cytoplasmic substrates of activated tyrosine kinases and are widely expressed in mammalian somatic tissues. Experiments were designed to demonstrate the presence of Shc in spermatozoa and to study its involvement in the signal transduction events leading to acrosome reaction. Anti-Shc antibodies strongly reacted with the acrosomal region of methanol-fixed human sperm. Only one Shc isoform (p52Shc) was detected on Western blot. To study the degree of phosphorylation of Shc during capacitation and acrosome reaction, sperm samples were divided into two groups: noncapacitated and capacitated/progesterone treated. Lysates from both groups were immunoprecipitated with anti-phosphotyrosine antibodies and the precipitated (i.e., phosphorylated) proteins were tested with anti-Shc antibodies. The intensity of p52Shc was clearly increased in capacitated/progesterone-stimulated cells.
Insights
Shc proteins are present in human sperm and become more phosphorylated during capacitation and the acrosome reaction, suggesting their role in these crucial reproductive processes.
Area of Science:
- Reproductive Biology
- Cell Signaling
- Sperm Physiology
Background:
- Tyrosine kinases are implicated in sperm capacitation and acrosome reaction.
- Shc proteins are cytoplasmic substrates of tyrosine kinases, found in mammalian somatic cells.
Purpose of the Study:
- To investigate the presence and role of Shc proteins in human spermatozoa.
- To explore Shc protein involvement in signal transduction pathways governing the acrosome reaction.
Main Methods:
- Immunohistochemical staining of human sperm with anti-Shc antibodies.
- Western blot analysis to identify Shc isoforms in spermatozoa.
- Phosphorylation analysis of Shc proteins during sperm capacitation and progesterone stimulation.
Main Results:
- Anti-Shc antibodies showed strong reactivity in the acrosomal region of human sperm.
- The p52Shc isoform was the predominant Shc protein detected in sperm.
- Increased phosphorylation of p52Shc was observed in capacitated and progesterone-stimulated sperm cells.
Conclusions:
- Shc proteins, specifically the p52Shc isoform, are present in human spermatozoa.
- Shc protein phosphorylation increases during sperm capacitation and acrosome reaction, indicating a role in these events.