TY - JOUR
T1 - Nucleoprotein transitions during spermiogenesis in mice with transition nuclear protein Tnp1 and Tnp2 mutations
AU - Zhao, Ming
AU - Shirley, Cynthia R.
AU - Mounsey, Suzanne
AU - Meistrich, Marvin L.
PY - 2004/9
Y1 - 2004/9
N2 - Chromatin remodeling during spermiogenesis is characterized by a series of nuclear protein replacements. Histories are replaced by transition nuclear proteins, which are in turn replaced by protamines. The transition nuclear proteins, TP1 and TP2, and the protamines, PRM1 and PRM2, are the major nuclear proteins involved in this process. Biochemical studies of mice with null mutations in one of the Tnp genes showed that the absence of one TP led to an apparent elevation in the amount of the remaining TP in the testis. To investigate the mechanism of changes of protein levels and effects of one Tnp mutation on other nuclear proteins, we used immunohistochemistry techniques to determine the distribution of these nuclear proteins. In contrast to previous biochemical analyses, which indicated that nuclear protein replacement was sequential with little overlap between the protein types, we found considerable overlap in the nucleoprotein types during spermiogenesis. The TPs, which appear in the nucleus before histone displacement is complete, were shared among genetically inequivalent spermatids. The absence of one TP did not affect the time of appearance of the other TP or of the protamines, but it did affect the displacement of the other TP, leading to its abnormal retention in the nucleus. The elevated levels of the remaining TP in Tnp-mutant mice appeared to be a consequence of the prolonged retention, rather than increased synthesis. Thus the absence of one of the TPs did not significantly affect transcription or translation of the other basic proteins, but it did affect posttranslational events.
AB - Chromatin remodeling during spermiogenesis is characterized by a series of nuclear protein replacements. Histories are replaced by transition nuclear proteins, which are in turn replaced by protamines. The transition nuclear proteins, TP1 and TP2, and the protamines, PRM1 and PRM2, are the major nuclear proteins involved in this process. Biochemical studies of mice with null mutations in one of the Tnp genes showed that the absence of one TP led to an apparent elevation in the amount of the remaining TP in the testis. To investigate the mechanism of changes of protein levels and effects of one Tnp mutation on other nuclear proteins, we used immunohistochemistry techniques to determine the distribution of these nuclear proteins. In contrast to previous biochemical analyses, which indicated that nuclear protein replacement was sequential with little overlap between the protein types, we found considerable overlap in the nucleoprotein types during spermiogenesis. The TPs, which appear in the nucleus before histone displacement is complete, were shared among genetically inequivalent spermatids. The absence of one TP did not affect the time of appearance of the other TP or of the protamines, but it did affect the displacement of the other TP, leading to its abnormal retention in the nucleus. The elevated levels of the remaining TP in Tnp-mutant mice appeared to be a consequence of the prolonged retention, rather than increased synthesis. Thus the absence of one of the TPs did not significantly affect transcription or translation of the other basic proteins, but it did affect posttranslational events.
KW - Sperm
KW - Sperm maturation
KW - Spermatid
KW - Spermatogenesis
KW - Testis
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U2 - 10.1095/biolreprod.104.028191
DO - 10.1095/biolreprod.104.028191
M3 - Article
C2 - 15163613
AN - SCOPUS:4243175916
SN - 0006-3363
VL - 71
SP - 1016
EP - 1025
JO - Biology of reproduction
JF - Biology of reproduction
IS - 3
ER -