Hiroshi Harayama


Affiliation: Kobe University
Country: Japan


  1. Arai Y, Sakase M, Fukushima M, Harayama H. Identification of isoforms of calyculin A-sensitive protein phosphatases which suppress full-type hyperactivation in bull ejaculated spermatozoa. Theriogenology. 2019;129:46-53 pubmed publisher
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    Harayama H, Sasaki K, Miyake M. A unique mechanism for cyclic adenosine 3',5'-monophosphate-induced increase of 32-kDa tyrosine-phosphorylated protein in boar spermatozoa. Mol Reprod Dev. 2004;69:194-204 pubmed
    ..Based on these results, we conclude that the cAMP-induced increase of TyrP32 is regulated by a unique mechanism that may be linked to the calcium-dependent change and loss of acrosomes. ..
  3. Harayama H, Nishijima K, Murase T, Sakase M, Fukushima M. Relationship of protein tyrosine phosphorylation state with tolerance to frozen storage and the potential to undergo cyclic AMP-dependent hyperactivation in the spermatozoa of Japanese Black bulls. Mol Reprod Dev. 2010;77:910-21 pubmed publisher
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    Harayama H, Murase T, Miyake M. A cyclic adenosine 3',5'-monophosphate stimulates phospholipase Cgamma1-calcium signaling via the activation of tyrosine kinase in boar spermatozoa. J Androl. 2005;26:732-40 pubmed
  5. Isono A, Tate S, Nakamura Mori K, Noda T, Ishikawa S, Harayama H. Involvement of cAMP-dependent unique signaling cascades in the decrease of serine/threonine-phosphorylated proteins in boar sperm head. Theriogenology. 2016;85:1152-60 pubmed publisher
  6. Ogura Y, Takagishi Y, Harayama H. Changes in the distribution and molecular mass of boar sperm acrosome-associated 1 proteins during the acrosome reaction; their validity as indicators for occurrence of the true acrosome reaction. Anim Reprod Sci. 2016;172:94-104 pubmed publisher
    ..Moreover, we suggest the increase of small types of SPACA1 proteins is a valid indicator for occurrence of the acrosomal disintegration arising from the true and false acrosome reactions. ..
  7. Fukuda M, Sakase M, Fukushima M, Harayama H. Changes of IZUMO1 in bull spermatozoa during the maturation, acrosome reaction, and cryopreservation. Theriogenology. 2016;86:2179-2188.e3 pubmed publisher
    ..These findings indicate that impaired fertilizing ability of bull cryopreserved spermatozoa with damaged acrosomes is related partially to the aberrant translocation of IZUMO1 which may be followed by the loss of intact IZUMO1. ..
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    Harayama H, Muroga M, Miyake M. A cyclic adenosine 3',5'-monophosphate-induced tyrosine phosphorylation of Syk protein tyrosine kinase in the flagella of boar spermatozoa. Mol Reprod Dev. 2004;69:436-47 pubmed
    ..Based on these findings, we have concluded that the cAMP-PKA signaling is linked to the Ca2+-independent tyrosine phosphorylation of Syk in the connecting and principal pieces of boar spermatozoa...
  9. Harayama H, Nakamura K. Changes of PKA and PDK1 in the principal piece of boar spermatozoa treated with a cell-permeable cAMP analog to induce flagellar hyperactivation. Mol Reprod Dev. 2008;75:1396-407 pubmed publisher
    ..These findings suggest that dephosphorylation of PDK1 may be a molecular switch for enhancement of protein tyrosine phosphorylation and flagellar hyperactivation in boar spermatozoa. ..

More Information


  1. Harayama H, Noda T, Ishikawa S, Shidara O. Relationship between cyclic AMP-dependent protein tyrosine phosphorylation and extracellular calcium during hyperactivation of boar spermatozoa. Mol Reprod Dev. 2012;79:727-39 pubmed publisher