Evidence for the activation of PAR-2 by the sperm protease, acrosin: expression of the receptor on oocytes.
Proteinase-activated receptor-2 (PAR-2) is a member of a family of G-protein-coupled, seven-transmembrane domain receptors that are activated by proteolytic cleavage. The receptor is expressed in a number of different tissues and potential physiological activators identified thus far include trypsin and mast cell tryptase. Acrosin, a trypsin-like serine proteinase found in spermatozoa of all mammals, was found to cleave a model peptide fluorescent quenched substrate representing the cleavage site of PAR-2. This substrate was cleaved with kinetics similar to those of the known PAR-2 activators, trypsin and mast cell tryptase. Acrosin was also shown to induce significant intracellular calcium responses in Chinese hamster ovary cells stably expressing intact human PAR-2, most probably due to activation of the receptor. Immunohistochemical studies using PAR-2 specific antibodies indicated that the receptor is expressed by mouse oocytes, which suggests that acrosin may play additional role(s) in the fertilization process via the activation of PAR-2 on oocytes.
Smith
R
R
Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia.
Jenkins
A
A
Lourbakos
A
A
Thompson
P
P
Ramakrishnan
V
V
Tomlinson
J
J
Deshpande
U
U
Johnson
D A
DA
Jones
R
R
Mackie
E J
EJ
Pike
R N
RN
D000176:Acrosin / Q000378:metabolism*; D000818:Animals; D016466:CHO Cells; D002118:Calcium / Q000378:metabolism*; D006224:Cricetinae; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D051379:Mice; D009865:Oocytes / Q000502:physiology*; D044464:Receptor, PAR-2; D018179:Receptors, Thrombin / Q000235:genetics / Q000502:physiology*; D011994:Recombinant Proteins / Q000378:metabolism; D013094:Spermatozoa / Q000201:enzymology*; D014162:Transfection; D014357:Trypsin / Q000378:metabolism
D044464:Receptor, PAR-2; D018179:Receptors, Thrombin; D011994:Recombinant Proteins; D000176:Acrosin; D014357:Trypsin; D002118:Calcium