Phosphorylation of Shc proteins in human sperm in response to capacitation and progesterone treatment

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 (ie, phosphorylated) proteins were tested with anti‐Shc antibodies. The intensity of p52Shc was clearly increased in capacitated/progesterone‐stimulated cells. Mol. Reprod. Dev. 50:113–120, 1998. © 1998 Wiley‐Liss, Inc.

Untitled

“…The MAPK isoform ERK2 [71], the adaptor protein Shc [74] and Ras [56] have been localized in human sperm head indicating that this pathway may be required for regulating protein phosphorylation in sperm. It has been speculated that MAP kinase may phosphorylate proteins that influence protein tyrosine phosphorylation indirectly.…”

Signaling via Shc family adapter proteins

“…The 66 kDa isoform of ShcA is expressed in most cells except in the hematopoietic lineage and contains an additional amino-terminal CH-like region (denoted CH2) Pelicci et al, 1992; Figure 1). The tyrosine phosphorylation of Shc has been noticed upon engagement of numerous cell surface receptors such as growth factor receptors (Gelderloos et al, 1998;Pelicci et al, 1992;Pronk et al, 1994;Rozakis-Adcock et al, 1992;Sasaoka et al, 1994;Stephens et al, 1994;Yokote et al, 1994); antigen receptors (Ravichandran et al, 1993;Saxton et al, 1994); cytokine receptors (Burns et al, 1993;Damen et al, 1993;Lioubin et al, 1994;Matsuguchi et al, 1994;Pratt et al, 1996;Ravichandran and Burako , 1994;Velazquez et al, 2000); G-protein coupled receptors and hormone receptors (Erwin et al, 1995;Kousteni et al, 2001;Migliaccio et al, 1996;Morte et al, 1998). In addition, a role for Shc has been ascribed in transformation by the polyoma middle T antigen and BCR ± ABL (Campbell et al, 1994;Goga et al, 1995;Mullane et al, 1998;Puil et al, 1994;Zhu et al, 1998).…”

Nongenomic Effects of Progesterone on Spermatozoa: Mechanisms of Signal Transduction and Clinical Implications

“…P hosphorylation of ER K -2 m ay occu r through activ ation of ras/ER K cascade, since both ras [ 57] and M EK-1 ( the upstream kinase responsible of ER K phosphorylation) [ 56] have been show n to be present in human sperm. Another sperm protein that undergoes tyrosin e phosphorylation in response to P and during capacitation is p52Shc [ 58] , a classical cytoplasm ic substrate of activ ated tyrosine kinases in som atic cells. The role of p52shc in P-mediated eÚ ects in hum an sperm has not yet been de ned [ 58] .…”

“…Another sperm protein that undergoes tyrosin e phosphorylation in response to P and during capacitation is p52Shc [ 58] , a classical cytoplasm ic substrate of activ ated tyrosine kinases in som atic cells. The role of p52shc in P-mediated eÚ ects in hum an sperm has not yet been de ned [ 58] .…”