TY - JOUR
T1 - Phosphorylation protects sperm-specific histones H1 and H2B from proteolysis after fertilization
AU - Morin, Violeta
AU - Acuña, Pamela
AU - Díaz, Freddy
AU - Inostroza, Diana
AU - Martinez, Jose
AU - Montecino, Martin
AU - Puchi, Marcia
AU - Imschenetzky, Maria
PY - 1999
Y1 - 1999
N2 - At intermediate stages of male pronucleus formation, sperm- derived chromatin is composed of hybrid nucleoprotein particles formed by sperm H1 (SpH1), dimers of sperm H2A-H2B (SpH2A-SpH2B), and a subset of maternal cleavage stage (CS) histone variants. At this stage in vivo, the CS histone variants are poly(ADP- ribosylated), while SpH2B and SpH1 are phosphorylated. We have postulated previously that the final steps of sperm chromatin remodeling involve a cysteine-protease (SpH-protease) that degrades sperm histones in a specific manner, leaving the maternal CS histone variants unaffected. More recently we have reported that the protection of CS histones from degradation is determined by the poly(ADP-ribose) moiety of these proteins. Because of the selectivity displayed by the SpH-protease, the coexistence of a subset of SpH together with CS histone variants at intermediate stages of male pronucleus remodeling remains intriguing. Consequently, we have investigated the phosphorylation state of SpH1 and SpH2B in relation to the possible protection of these proteins from proteolytic degradation. Histones H1 and H2B were purified from sperm, phosphorylated in vitro using the recombinant α-subunit of casein kinase 2, and then used as substrates in the standard assay of the SpH-protease. The phosphorylated forms of SpH1 and SpH2B were found to remain unaltered, while the nonphosphorylated forms were degraded. On the basis of this result, we postulate a novel role for the phosphorylation of SpH1 and SpH2B that occurs in vivo after fertilization, namely to protect these histones against degradation at intermediate stages of male chromatin remodeling.
AB - At intermediate stages of male pronucleus formation, sperm- derived chromatin is composed of hybrid nucleoprotein particles formed by sperm H1 (SpH1), dimers of sperm H2A-H2B (SpH2A-SpH2B), and a subset of maternal cleavage stage (CS) histone variants. At this stage in vivo, the CS histone variants are poly(ADP- ribosylated), while SpH2B and SpH1 are phosphorylated. We have postulated previously that the final steps of sperm chromatin remodeling involve a cysteine-protease (SpH-protease) that degrades sperm histones in a specific manner, leaving the maternal CS histone variants unaffected. More recently we have reported that the protection of CS histones from degradation is determined by the poly(ADP-ribose) moiety of these proteins. Because of the selectivity displayed by the SpH-protease, the coexistence of a subset of SpH together with CS histone variants at intermediate stages of male pronucleus remodeling remains intriguing. Consequently, we have investigated the phosphorylation state of SpH1 and SpH2B in relation to the possible protection of these proteins from proteolytic degradation. Histones H1 and H2B were purified from sperm, phosphorylated in vitro using the recombinant α-subunit of casein kinase 2, and then used as substrates in the standard assay of the SpH-protease. The phosphorylated forms of SpH1 and SpH2B were found to remain unaltered, while the nonphosphorylated forms were degraded. On the basis of this result, we postulate a novel role for the phosphorylation of SpH1 and SpH2B that occurs in vivo after fertilization, namely to protect these histones against degradation at intermediate stages of male chromatin remodeling.
KW - Chromatin
KW - Histone phosphorylation
KW - Male pronucleus
KW - Protease
UR - http://www.scopus.com/inward/record.url?scp=0033427738&partnerID=8YFLogxK
U2 - 10.1002/(SICI)1097-4644(20000201)76:2<173::AID-JCB1>3.0.CO;2-7
DO - 10.1002/(SICI)1097-4644(20000201)76:2<173::AID-JCB1>3.0.CO;2-7
M3 - Article
C2 - 10618634
VL - 76
SP - 173
EP - 180
JO - Journal of supramolecular structure and cellular biochemistry
JF - Journal of supramolecular structure and cellular biochemistry
SN - 0730-2312
IS - 2
ER -