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Gene Review

CBX4  -  chromobox homolog 4

Homo sapiens

Synonyms: Chromobox protein homolog 4, E3 SUMO-protein ligase CBX4, NBP16, PC2, Pc2, ...
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Disease relevance of CBX4


High impact information on CBX4


Biological context of CBX4

  • Interference with the expression of a novel human polycomb protein, hPc2, results in cellular transformation and apoptosis [1].
  • Our data suggest that hPc2 is a repressor of proto-oncogene activity and that interference with hPc2 function can lead to derepression of proto-oncogene transcription and subsequently to cellular transformation [1].
  • Expression of the delta hPc2 protein, but not of the wild-type hPc2 protein, results in cellular transformation of mammalian cell lines as judged by phenotypic changes, altered marker gene expression, and anchorage-independent growth [1].
  • Inducible phosphorylation of Pc2 at threonine 495 is required for its ability to increase HIPK2 sumoylation in response to DNA damage, thereby establishing an autoregulatory feedback loop between a SUMO substrate and its cognate E3 ligase [5].
  • The PCA of the 1H NMR spectra of the aqueous fractions allowed a clear discrimination between antler samples according to their origins by the first three principal components (PC1, PC2, and PC3), which cumulatively accounted for 93.5% of the variation in all variables [8].

Anatomical context of CBX4

  • This concurs with the absence of prohormone convertase 2 (PC2) in the embryo, whereas PC2 is present later in embryonic pancreas [9].
  • In both AtT-20 cells and hEK-293 cells, the PAM/PC2 fusion molecule was able to exit the endoplasmic reticulum more rapidly than PC2 [10].
  • In this report, the regulatory role of actin dynamics on PC2 channels reconstituted from hST apical membranes was explored [11].
  • PC2 could only be detected in normal adrenal glands using the sensitive RT/PCR technique [3].
  • It has been previously shown that PMs and synthetic particles (PC10 and PC2) that have similar characteristics to PMs induced depolarizing currents and increases in intracellular calcium ([Ca2+]i) in capsaicin- and acid-sensitive sensory neurons and in TRPV1-expressing HEK 293 cells [12].

Associations of CBX4 with chemical compounds

  • Immobilized template assays in which activator-recruited preinitiation complexes were allowed to undergo one cycle of transcription revealed partial disruption of Mediator that resulted in a PC2-like complex being retained in the scaffold [13].
  • Aspartate at the oxyanion hole appears to confer k(caf) discrimination between substrates by raising the energy barrier for productive substrate binding: this may have implications for pro-insulin processing by the PC2 protease, which has an aspartate at the equivalent position [14].
  • To elucidate the mechanism of this disease, we stably expressed five vasopressin prohormones with a mutation in the neurophysin moiety (NP14G-->R, NP47E-->G, NP47DeltaE, NP57G-->S, and NP65G-->V) in the neuroendocrine cell lines Neuro-2A and PC12/PC2 [15].
  • Curiously, the mammalian protease PC2, a Kex2 homolog that is likely to be required for pro-insulin processing, has an aspartate in place of asparagine at the 'oxyanion hole'. RESULTS: We have tested the effect of making substitutions of the conserved oxyanion-hole asparagine (Asn 314) of the Kex2 protease [14].
  • Two most effective detection potentials were selected: 780 mV for the GSSG and PC2 and 680 mV for determination of Cys and GSH [16].

Other interactions of CBX4

  • The human PcG protein, Pc2, has been shown to recruit the transcriptional corepressor, CtBP, to PcG bodies [4].
  • The interactions between Ring1, hPc2, and KyoT2 were confirmed by changing vectors in two-hybrid analysis [17].
  • Interactions of KyoT2 with Ring1 and hPc2 suggested that PcG family might be involved in Notch signaling pathway [17].

Analytical, diagnostic and therapeutic context of CBX4


  1. Interference with the expression of a novel human polycomb protein, hPc2, results in cellular transformation and apoptosis. Satijn, D.P., Olson, D.J., van der Vlag, J., Hamer, K.M., Lambrechts, C., Masselink, H., Gunster, M.J., Sewalt, R.G., van Driel, R., Otte, A.P. Mol. Cell. Biol. (1997) [Pubmed]
  2. Characterization of a high copy number amplification at 6q24 in pancreatic cancer identifies c-myb as a candidate oncogene. Wallrapp, C., Müller-Pillasch, F., Solinas-Toldo, S., Lichter, P., Friess, H., Büchler, M., Fink, T., Adler, G., Gress, T.M. Cancer Res. (1997) [Pubmed]
  3. Co-expression of PC2 and proenkephalin in human tumoral adrenal medullary tissues. Konoshita, T., Gasc, J.M., Villard, E., Seidah, N.G., Corvol, P., Pinet, F. Biochimie (1994) [Pubmed]
  4. The polycomb protein Pc2 is a SUMO E3. Kagey, M.H., Melhuish, T.A., Wotton, D. Cell (2003) [Pubmed]
  5. Phosphorylation-Dependent Control of Pc2 SUMO E3 Ligase Activity by Its Substrate Protein HIPK2. Roscic, A., M??ller, A., Calzado, M.A., Renner, F., Wimmer, V.C., Gresko, E., L??di, K.S., Schmitz, M.L. Mol. Cell (2006) [Pubmed]
  6. Synaptotagmin IV is necessary for the maturation of secretory granules in PC12 cells. Ahras, M., Otto, G.P., Tooze, S.A. J. Cell Biol. (2006) [Pubmed]
  7. Multiple activities contribute to Pc2 E3 function. Kagey, M.H., Melhuish, T.A., Powers, S.E., Wotton, D. EMBO J. (2005) [Pubmed]
  8. Metabolomic differentiation of deer antlers of various origins by 1H NMR spectrometry and principal components analysis. Choi, H.K., Kim, K.H., Kim, K.H., Kim, Y.S., Lee, M.W., Whang, W.K. Journal of pharmaceutical and biomedical analysis. (2006) [Pubmed]
  9. Unprocessed proinsulin promotes cell survival during neurulation in the chick embryo. Hernández-Sánchez, C., Rubio, E., Serna, J., de la Rosa, E.J., de Pablo, F. Diabetes (2002) [Pubmed]
  10. The NH2-terminal proregion of peptidylglycine alpha-amidating monooxygenase facilitates the secretion of soluble proteins. Mains, R.E., Milgram, S.L., Keutmann, H.T., Eipper, B.A. Mol. Endocrinol. (1995) [Pubmed]
  11. Cytoskeletal regulation of calcium-permeable cation channels in the human syncytiotrophoblast: role of gelsolin. Montalbetti, N., Li, Q., Timpanaro, G.A., González-Perrett, S., Dai, X.Q., Chen, X.Z., Cantiello, H.F. J. Physiol. (Lond.) (2005) [Pubmed]
  12. Vanilloid receptor activation by 2- and 10-microm particles induces responses leading to apoptosis in human airway epithelial cells. Agopyan, N., Bhatti, T., Yu, S., Simon, S.A. Toxicol. Appl. Pharmacol. (2003) [Pubmed]
  13. Structural and functional characterization of PC2 and RNA polymerase II-associated subpopulations of metazoan Mediator. Malik, S., Baek, H.J., Wu, W., Roeder, R.G. Mol. Cell. Biol. (2005) [Pubmed]
  14. One-step site-directed mutagenesis of the Kex2 protease oxyanion hole. Brenner, C., Bevan, A., Fuller, R.S. Curr. Biol. (1993) [Pubmed]
  15. Mutations in the vasopressin prohormone involved in diabetes insipidus impair endoplasmic reticulum export but not sorting. Nijenhuis, M., Zalm, R., Burbach, J.P. J. Biol. Chem. (1999) [Pubmed]
  16. Simultaneous femtomole determination of cysteine, reduced and oxidized glutathione, and phytochelatin in maize (Zea mays L.) kernels using high-performance liquid chromatography with electrochemical detection. Potesil, D., Petrlova, J., Adam, V., Vacek, J., Klejdus, B., Zehnalek, J., Trnkova, L., Havel, L., Kizek, R. Journal of chromatography. A. (2005) [Pubmed]
  17. The interactions of LIM protein KyoT with polycomb proteins. Li, R., Zhang, R. Sheng Wu Hua Xue Yu Sheng Wu Wu Li Xue Bao (2003) [Pubmed]
  18. Interpretation of the repetitive nerve stimulation test results using principal component analysis. Cengiz, B., Kuruoğlu, H.R. Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology. (2006) [Pubmed]
  19. Robust sensor fusion improves heart rate estimation: clinical evaluation. Feldman, J.M., Ebrahim, M.H., Bar-Kana, I. Journal of clinical monitoring. (1997) [Pubmed]
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