High impact information on Mos

• In vertebrates, unfertilized eggs are arrested at second meiotic metaphase by a cytostatic factor (CSF), an essential component of which is the product of the c-mos proto-oncogene [1].
• We now report that transcripts of c-rasK and c-myc genes are significantly elevated after partial hepatectomy, whereas transcripts of c-abl and c-src are essentially unchanged and transcripts of c-mos are undetectable in either normal or regenerating rat liver [2].
• Surprisingly, when the three cell types are growing at similar rates only, one protooncogene (c-mos) is not expressed at detectable levels in L6 alpha 1, two others (c-fos, c-erbA) are not expressed in M4 or in RMS4, and three additional ones (c-erbB, c-sis, c-src) are expressed in M4 but not in RMS4 [3].
• When the MAP kinase of G2-arrested starfish or Xenopus oocytes was prematurely activated by microinjection of c-mos or Ste-11 delta N fusion proteins, the rate and extent of MPF inactivation was much reduced [4].
• The presence of Mos was initially demonstrated at 6 h after meiosis reinitiation and was associated with its mRNA polyadenylation [5].

Biological context of Mos

• Activation of members of the MAPK family, Erk 1 and 2, in oocytes resuming meiosis is regulated by Mos [5].
• Rat myogenic c-mos cDNA: cloning sequence analysis and regulation during muscle development [6].
• We have isolated and sequenced a cDNA clone, homologous to the rat c-mos gene, from a cDNA library of rat skeletal muscles [6].
• Some facts render c-mos unique among the oncogenes : a) it does not contain intervening sequences and b) its expression was never detected in a large number of normal mouse tissues examined [7].
• Complete c-mos (rat) nucleotide sequence: presence of conserved domains in c-mos proteins [7].

Anatomical context of Mos

• We found that meiotically arrested rat oocytes express the c-mos mRNA with no detectable Mos protein [5].
• These results suggest that the phosphorylation of the 34 kDa protein by the c-mos signal may play a crucial role in the meiotic division of rat spermatocytes [8].
• Identification of the testis c-mos promoter: specific activity in a seminiferous tubule-derived extract and binding of a testis-specific nuclear factor [9].
• The c-mos proto-oncogene is predominantly expressed in male and female germ cells and is involved in the regulation of meiosis [9].
• Footprinting analyses showed that nuclear proteins from L6 alpha 1 myoblasts protected a DNA fragment located at position nt -979 to nt -938 relative to the first ATG of the rat c-mos ORF while nuclear proteins from myotubes protected the DNA between nt -998 to nt -928 [10].

Associations of Mos with chemical compounds

• The treatment with proteasome inhibitor, MG132 or Ca(2+)-chelator, BAPTA-AM, overcame the spontaneous degradation of both Mos and cyclin B1 in a dose-dependent manner in Wistar oocytes [11].
• Polyadenylation of c-mos mRNA was also prevented by roscovitine, which is a potent inhibitor of p34cdc2 [5].
• In vitro phosphorylation of the c-mos immune complexes revealed a 34 kDa protein that was phosphorylated at serine and threonine residues as a target of the c-mos signal [8].
• Hence, it might be suggested that in C6 cells c-mos is down-regulated from other factors and/or genes, or requires for its activation overexpression of other genes [12].
• The 43K c-mos protein had a pI value of around 9.0-9.6 having a hydrophobic nature, and was phosphorylated in vitro on serine [13].

Other interactions of Mos

• The 43K c-mos protein was partially purified from rat testes and the protein band was identified [13].

Analytical, diagnostic and therapeutic context of Mos

• By Northern blot analysis, we detected two c-mos transcripts, one major of about 3.6 Kb long, and one minor of about 1.7 Kb long [6].
• Gel filtration and crosslinking experiments show that a 170 kDa complex contains c-mos and p34cdc2 proteins [14].
• We have used fractionation of subcellular components of the skeletal muscle followed by Western blot analyses to study the localization of the c-mos protein in adult rat muscle [14].
• This was achieved by characterization of the rat testis c-mos transcription start site by primer extension and sequence analysis of cDNAs obtained by polymerase chain reaction amplification of 5' ends of c-mos RNA [9].
• DNAase I footprint analysis and gel-retardation assays showed binding of a novel testis-specific nuclear factor to the rat testis c-mos promoter at a site homologous to the testis-specific cis-acting element identified in the promoter of the RT7 gene, which is specifically expressed in haploid male germ cells [9].

References