PAWP, a sperm-specific WW domain-binding protein, promotes meiotic resumption and pronuclear development during fertilization.
We report a novel alkaline extractable protein of the sperm head that exclusively resides in the post-acrosomal sheath region of the perinuclear theca (PT) and is expressed and assembled in elongating spermatids. It is a protein that shares sequence homology to the N-terminal half of WW domain-binding protein 2, while the C-terminal half is unique and rich in proline. A functional PPXY consensus binding site for group-I WW domain-containing proteins, and numerous unique repeating motifs, YGXPPXG, are identified in the proline-rich region. Considering these molecular characteristics, we designated this protein PAWP for postacrosomal sheath WW domain-binding protein. Microinjection of recombinant PAWP or alkaline PT extract into metaphase II-arrested porcine, bovine, macaque, and Xenopus oocytes induced a high rate of pronuclear formation, which was prevented by co-injection of a competitive PPXY motif containing peptide derived from PAWP but not by co-injection of the point-mutated peptide. Intracytoplasmic sperm injection (ICSI) of porcine oocytes combined with co-injection of the competitive PPXY peptide or an anti-recombinant PAWP antiserum prevented pronuclear formation and arrested fertilization. Conversely, co-injection of the modified PPXY peptide, when the tyrosine residue of PPXY was either phosphorylated or substituted with phenylalanine, did not prevent ICSI-induced fertilization. This study uncovers a group I WW domain module signal transduction event within the fertilized egg that appears compulsory for meiotic resumption and pronuclear development during egg activation and provides compelling evidence that a PPXY motif of sperm-contributed PAWP can trigger these events.
Wu
Alexander T H
AT
Department of Anatomy and Cell Biology, Queen's University, Kingston, Ontario K7L 3N6, Canada.
Sutovsky
Peter
P
Manandhar
Gaurishankar
G
Xu
Wei
W
Katayama
Mika
M
Day
Billy N
BN
Park
Kwang-Wook
KW
Yi
Young-Joo
YJ
Xi
Yan Wei
YW
Prather
Randall S
RS
Oko
Richard
R
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology*; D002417:Cattle; D002467:Cell Nucleus / Q000378:metabolism*; D005260:Female; D005306:Fertilization; D005307:Fertilization in Vitro; D008251:Macaca; D008297:Male; D008540:Meiosis; D008969:Molecular Sequence Data; D029589:Seminal Plasma Proteins / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D013094:Spermatozoa / Q000378:metabolism*; D013552:Swine; D014981:Xenopus
D002352:Carrier Proteins; C519841:PAWP protein, mouse; D029589:Seminal Plasma Proteins; C519840:WBP2NL protein, human