PMID- 10068474
OWN - NLM
STAT- MEDLINE
DCOM- 19990503
LR  - 20190423
IS  - 0012-1606 (Print)
IS  - 0012-1606 (Linking)
VI  - 207
IP  - 2
DP  - 1999 Mar 15
TI  - Involvement of Chk1 kinase in prophase I arrest of Xenopus oocytes.
PG  - 432-44
AB  - Chk1 kinase, a DNA damage/replication G2 checkpoint kinase, has recently been
      shown to phosphorylate and inhibit Cdc25C, a Cdc2 Tyr-15 phosphatase, thereby
      directly linking the G2 checkpoint to negative regulation of Cdc2. Immature
      Xenopus oocytes are arrested naturally at the first meiotic prophase (prophase I)
      or the late G2 phase, with sustained Cdc2 Tyr-15 phosphorylation. Here we have
      cloned a Xenopus homolog of Chk1, determined its developmental expression, and
      examined its possible role in prophase I arrest of oocytes. Xenopus Chk1 protein 
      is expressed at approximately constant levels throughout oocyte maturation and
      early embryogenesis. Overexpression of wild-type Chk1 in oocytes prevents the
      release from prophase I arrest by progesterone. Conversely, specific inhibition
      of endogenous Chk1 either by overexpression of a dominant-negative Chk1 mutant or
      by injection of a neutralizing anti-Chk1 antibody facilitates prophase I release 
      by progesterone. Moreover, when ectopically expressed in oocytes, a
      Chk1-nonphosphorylatable Cdc25C mutant alone can induce prophase I release much
      more efficiently than wild-type Cdc25C; if endogenous Chk1 function is inhibited,
      however, even wild-type Cdc25C can induce the release very efficiently. These
      results suggest strongly that Chk1 is involved in physiological prophase I arrest
      of Xenopus oocytes via the direct phosphorylation and inhibition of Cdc25C. We
      discuss the possibility that Chk1 might function either as a G2 checkpoint kinase
      or as an ordinary cell cycle regulator in prophase-I-arrested oocytes.
CI  - Copyright 1999 Academic Press.
FAU - Nakajo, N
AU  - Nakajo N
AD  - Faculty of Science, Kyushu University, Hakozaki 6-10-1, Fukuoka, 812-8581, Japan.
FAU - Oe, T
AU  - Oe T
FAU - Uto, K
AU  - Uto K
FAU - Sagata, N
AU  - Sagata N
LA  - eng
SI  - GENBANK/AB019218
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - United States
TA  - Dev Biol
JT  - Developmental biology
JID - 0372762
RN  - 0 (Cell Cycle Proteins)
RN  - 0 (RNA, Messenger)
RN  - 0 (Xenopus Proteins)
RN  - 4G7DS2Q64Y (Progesterone)
RN  - EC 2.7.- (Protein Kinases)
RN  - EC 2.7.11.1 (Checkpoint Kinase 1)
RN  - EC 2.7.11.1 (Chek1 protein, Xenopus)
RN  - EC 3.1.3.16 (Phosphoprotein Phosphatases)
RN  - EC 3.1.3.48 (cdc25 Phosphatases)
SB  - IM
MH  - Amino Acid Sequence
MH  - Animals
MH  - Base Sequence
MH  - Cell Cycle Proteins/antagonists & inhibitors/metabolism
MH  - Checkpoint Kinase 1
MH  - Cloning, Molecular
MH  - Embryonic Development
MH  - Gene Expression Regulation, Developmental
MH  - Meiosis/genetics
MH  - Microinjections
MH  - Molecular Sequence Data
MH  - Mutation
MH  - Oocytes/*enzymology/metabolism
MH  - Phosphoprotein Phosphatases/antagonists & inhibitors/metabolism
MH  - Phosphorylation
MH  - Progesterone/pharmacology
MH  - Prophase/genetics
MH  - Protein Kinases/*genetics/metabolism
MH  - RNA, Messenger/metabolism
MH  - Sequence Alignment
MH  - Time Factors
MH  - Xenopus/*embryology
MH  - Xenopus Proteins
MH  - *cdc25 Phosphatases
EDAT- 1999/03/09 00:00
MHDA- 1999/03/09 00:01
CRDT- 1999/03/09 00:00
PHST- 1999/03/09 00:00 [pubmed]
PHST- 1999/03/09 00:01 [medline]
PHST- 1999/03/09 00:00 [entrez]
AID - S0012-1606(98)99178-3 [pii]
AID - 10.1006/dbio.1998.9178 [doi]
PST - ppublish
SO  - Dev Biol. 1999 Mar 15;207(2):432-44. doi: 10.1006/dbio.1998.9178.