PMID- 10439036
OWN - NLM
STAT- MEDLINE
DCOM- 19990813
LR  - 20131121
IS  - 0950-9232 (Print)
IS  - 0950-9232 (Linking)
VI  - 18
IP  - 30
DP  - 1999 Jul 29
TI  - Evidence for an important role of serine 16 and its phosphorylation in the
      stabilization of c-Mos.
PG  - 4287-94
AB  - The c-Mos serine/threonine protein kinase is an essential component of cytostatic
      factor (CSF), which is required for metaphase II arrest of eggs in vertebrates.
      Previously, we showed that c-Mos residue Ser-16 is phosphorylated in the ts110
      Mo-MuSV-encoded Gag-Mos fusion protein. Here we provide evidence that Mos is
      phosphorylated at Ser-16 in transfected COS-1 cells. To investigate the role of
      this phosphorylation, Ser-16 was substituted with alanine or glutamic acid in
      full-length v-Mos (an Env-Mos fusion protein that contains 31 additional amino
      acids at the amino terminus of c-Mos), its mouse c-Mos equivalent version (v-Mos 
      residues 32-374, hereafter referred to as Mos), and mouse c-Mos. Constructs
      expressing mutant versions of Mos were transfected into COS-1 and NIH3T3 cells in
      a transient and stable manner, respectively. Synthesis and proteolysis of Mos
      were evaluated by pulse-chase analysis of 35S-methionine-labeled proteins. Our
      findings indicate that the S16A mutant of Mos was highly unstable. It accumulated
      to approximately 10% of the level of wild-type Mos or its S16E mutant. In
      addition, the S16A mutation but not the S16E mutation inhibited Mos interaction
      with a cellular protein, p35, suggesting that phosphorylation at Ser-16 may
      promote Mos interaction with p35. As expected from its destabilizing effect, the 
      S16A mutation caused a dramatic decrease in the cellular transforming activity of
      Mos (determined by soft-agar colony-formation assay with the stably transfected
      NIH3T3 cells), which is known to correlate with its CSF function. Efficient
      ubiquitin-mediated proteolysis of c-Mos requires proline as the second residue
      from the amino-terminus. In contrast to Mos, neither the stability nor protein
      kinase activity of v-Mos (in which c-Mos residue Pro-2 becomes Pro-33) was
      affected by the S16A mutation. To provide further proof that, similar to c-Mos,
      the S16A mutant is recognized by the proteolysis system through Pro-2, we show
      that the effect of the S16A mutation is reversed by the Pro-2-Ala mutation. Thus,
      our results indicate that Ser-16 has an important role in the regulation of c-Mos
      and that phosphorylation at Ser-16 may inhibit proteolysis of c-Mos.
FAU - Pham, C D
AU  - Pham CD
AD  - Department of Molecular Pathology, University of Texas MD Anderson Cancer Center,
      Houston 77030, USA.
FAU - Vuyyuru, V B
AU  - Vuyyuru VB
FAU - Yang, Y
AU  - Yang Y
FAU - Bai, W
AU  - Bai W
FAU - Singh, B
AU  - Singh B
LA  - eng
GR  - CA16672/CA/NCI NIH HHS/United States
GR  - R01 CA45125/CA/NCI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - England
TA  - Oncogene
JT  - Oncogene
JID - 8711562
RN  - 452VLY9402 (Serine)
RN  - EC 2.7.11.1 (Proto-Oncogene Proteins c-mos)
RN  - EC 2.7.11.17 (Calcium-Calmodulin-Dependent Protein Kinases)
RN  - EC 2.7.11.24 (Mitogen-Activated Protein Kinase 1)
RN  - EC 2.7.11.24 (Mitogen-Activated Protein Kinase 3)
RN  - EC 2.7.11.24 (Mitogen-Activated Protein Kinases)
SB  - IM
MH  - 3T3 Cells
MH  - Animals
MH  - COS Cells
MH  - Calcium-Calmodulin-Dependent Protein Kinases/metabolism
MH  - Chromatography
MH  - Electrophoresis, Gel, Pulsed-Field
MH  - Gene Expression Regulation, Enzymologic
MH  - Mice
MH  - Mitogen-Activated Protein Kinase 1
MH  - Mitogen-Activated Protein Kinase 3
MH  - *Mitogen-Activated Protein Kinases
MH  - Mutagenesis, Site-Directed
MH  - Phosphorylation
MH  - Precipitin Tests
MH  - Proto-Oncogene Proteins c-mos/metabolism/*physiology
MH  - Serine/*physiology
MH  - Time Factors
MH  - Transfection
MH  - Tumor Stem Cell Assay
EDAT- 1999/08/10 00:00
MHDA- 1999/08/10 00:01
CRDT- 1999/08/10 00:00
PHST- 1999/08/10 00:00 [pubmed]
PHST- 1999/08/10 00:01 [medline]
PHST- 1999/08/10 00:00 [entrez]
AID - 10.1038/sj.onc.1202804 [doi]
PST - ppublish
SO  - Oncogene. 1999 Jul 29;18(30):4287-94. doi: 10.1038/sj.onc.1202804.