title: SRC family kinases in hamster spermatozoa: evidence for the presence of LCK.
abstract: Sperm capacitation is a prerequisite for successful fertilization. Increase in tyrosine phosphorylation is considered the hallmark of capacitation and attempts to understand its regulation are ongoing. In this regard, we attempted to study the role of SRC family kinases (SFKs) in the hamster sperm functions. Interestingly, we found the presence of the lymphocyte-specific protein tyrosine kinase, LCK, in mammalian spermatozoa and further characterized it in terms of its localization and function. LCK was found in spermatozoa of several species, and its transcript was identified in the hamster testis. Autophosphorylation of LCK at the Y394 residue increased as capacitation progressed, indicating an upregulation of LCK activity during capacitation. Inhibition of LCK (and perhaps the other SFKs) with the use of a specific inhibitor showed a significant decrease in protein tyrosine phosphorylation of several proteins, implying LCK/SFKs as key tyrosine kinase(s) regulating tyrosine phosphorylation during hamster sperm capacitation. Dihydrolipoamide dehydrogenase was identified as a substrate for LCK/SFK. LCK/SFKs inhibition significantly reduced the percentage fertilization (in vitro) but had no effect on sperm motility, hyperactivation and acrosome reaction. In summary, this is the first report on the presence of LCK, an SFK of hematopoietic lineage in spermatozoa besides being the first study on the role of SFKs in the spermatozoa of Syrian hamsters.
authors.affiliation: CSIR-Centre for Cellular and Molecular BiologyHyderabad 500007, India 
  abs@ccmb.res.in
authors.forename: Durgesh Kumar
authors.initials: DK
authors.lastname: Singh
authors.affiliation: CSIR-Centre for Cellular and Molecular BiologyHyderabad 500007, India 
  abs@ccmb.res.in
authors.forename: Rohit Kumar
authors.initials: RK
authors.lastname: Deshmukh
authors.affiliation: CSIR-Centre for Cellular and Molecular BiologyHyderabad 500007, India 
  abs@ccmb.res.in
authors.forename: Praveen Kumar
authors.initials: PK
authors.lastname: Narayanan
authors.affiliation: CSIR-Centre for Cellular and Molecular BiologyHyderabad 500007, India 
  abs@ccmb.res.in
authors.forename: Sisinthy
authors.initials: S
authors.lastname: Shivaji
authors.affiliation: CSIR-Centre for Cellular and Molecular BiologyHyderabad 500007, India 
  abs@ccmb.res.in
authors.forename: Archana Bharadwaj
authors.initials: AB
authors.lastname: Siva
mesh_terms: D020101:Acrosome Reaction; D000818:Animals; D002478:Cells, Cultured; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism; D005260:Female; D005307:Fertilization in Vitro; D006801:Humans; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck) / Q000378:metabolism*; D008297:Male; D008647:Mesocricetus; D009865:Oocytes / Q000166:cytology / Q000502:physiology; D010766:Phosphorylation; D013075:Sperm Capacitation / Q000502:physiology*; D013081:Sperm Motility; D013094:Spermatozoa / Q000166:cytology / Q000502:physiology*; D013737:Testis / Q000166:cytology / Q000502:physiology*; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D014443:Tyrosine; D000242:Cyclic AMP; D019860:Lymphocyte Specific Protein Tyrosine Kinase p56(lck); D019061:src-Family Kinases