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Gene Review

CDC42SE1  -  CDC42 small effector 1

Homo sapiens

Synonyms: CDC42 small effector protein 1, CDC42-binding protein SCIP1, SCIP1, SPEC1, Small effector of CDC42 protein 1
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Disease relevance of CDC42SE1

  • Immunofluorescence experiments in NIH-3T3 fibroblasts demonstrated that both SPEC1 and SPEC2 showed a cortical localization and induced the formation of cell surface membrane blebs, which was not dependent on Cdc42 activity [1].
  • The other phage contain only partial homology to pSpec1 and pSpec2, 150 to 200 base pairs of the 3' untranslated region of the Spec1 and Spec2 mRNAs [2].
  • In both media, human oligodendroglioma cells expressed the A2B5 membrane marker as well as the SCIP transcription factor specific of 0-2 A cells, further confirming their oligodendrocytic origin [3].
  • The cell line SPEC-1, derived from a human serous papillary endometrial carcinoma (SPEC), has been established and repetitively subcultured for over 18 months [4].
  • We present the Israeli experience in the treatment of infertility in a large series of SCIP [5].

High impact information on CDC42SE1

  • We have previously shown that these mRNAs (termed Spec for Strongylocentrotus purpuratus ectoderm) accumulate in the presumptive dorsal ectoderm of post-cleavage stage embryos and code for a group of 10 to 12 low molecular weight acidic proteins [6].
  • Comparison of the translational reading frames of the Spec mRNAs with known protein sequences shows a significant homology with troponin C-related proteins, especially in the calcium-binding domains [6].
  • Our understanding of the transcriptional control of Schwann cell development, particularly by the POU protein SCIP and the zinc-finger protein Krox-20, has been advanced by transgenic, knockout, and expression studies [7].
  • CyIIIa is expressed only in aboral ectoderm lineages; the other genes studied were Spec1, also expressed in aboral ectoderm; CyI, expressed in many different cell types; and SM50, expressed only in skeletogenic mesenchyme [8].
  • As observed for Egr2, Nab proteins are necessary for Schwann cells to exit the cell cycle, downregulate suppressed cAMP-inducible protein (SCIP) expression and upregulate expression of critical myelination genes [9].

Chemical compound and disease context of CDC42SE1


Biological context of CDC42SE1

  • Cotransfection experiments demonstrated that SPEC1 altered Cdc42-induced cell shape changes both in COS1 cells and in NIH-3T3 fibroblasts and that this alteration required an intact CRIB domain [1].
  • This sequence also contains a 40 nucleotide region that is related to several tRNA sequences (containing the B box), and a 79 nucleotide sequence which is homologous to a repeated sequence previously shown to be present within the 3' untranslated portions of the Spec1 and Spec2 mRNAs of this species (1) [11].
  • These promoter analyses suggest that although SPEC1 and AF1q genes share the same promoter region, they are not coordinately regulated [12].
  • Identification and sequencing of different sized SPEC1 cDNA clones revealed that the transcript size heterogeneity was due to alternative splicing in the 3'-untranslated region [12].
  • This intergenic sequence containing the putative promoter region for both SPEC1 and AF1q genes did not contain a TATA box or CAAT box [12].

Anatomical context of CDC42SE1

  • The Spec1 and Spec2 genes are expressed specifically in aboral ectoderm cells of the developing embryo; however, the function of the Spec proteins in these cells is unknown [13].
  • Although the small Cdc42-binding proteins SPEC1 and SPEC2 play a role in F-actin accumulation in activated T lymphocytes, little is known about their precise activities in other cell types [14].
  • Biochemical studies revealed that SPEC1 did not interact with a Rac1 switch-of-function mutant capable of inducing Cdc42-like filopodia, potentially eliminating a role for SPECs in this process [14].
  • Spec 1, Spec 2c, and Spec 2d genes all appeared to be transcriptionally activated at the late cleavage-early blastula stage of S. purpuratus [15].
  • Estimations of the absolute rate constants for Spec 1 transcription were made at the late cleavage, mesenchyme blastula, and midgastrula stages [15].

Associations of CDC42SE1 with chemical compounds

  • Mutational analysis revealed that localization of SPEC1 to the TCR required two N-terminal cysteine residues [16].
  • A phosphoinositide-binding region was identified within a basic region N-terminal to the CRIB sequence of SPEC1 [14].
  • Repression of gonadotropin-releasing hormone promoter activity by the POU homeodomain transcription factor SCIP/Oct-6/Tst-1: a regulatory mechanism of phenotype expression [17]?
  • Phase and modulation spectra (PM Spec) were used to recover the emission spectra associated with the two decay times of tryptophan at pH = 7 (0.54 and 3.44 ns) [18].
  • Propoxyphene and norpropoxyphene quantitation in the same solid-phase extraction using Toxi-Lab Spec VC MP3 system [19].

Physical interactions of CDC42SE1

  • Although a Cdc42-binding mutant of SPEC1 still caused macrophage contraction, mutations within the N-terminal cysteines and phosphoinositide-binding region reversed macrophage contraction but still resulted in impaired phagocytosis [14].

Regulatory relationships of CDC42SE1


Other interactions of CDC42SE1

  • Examination of the 5'-end of the SPEC1 genomic sequence revealed that AF1q, a previously identified gene involved in translocations with the MLL (mixed-lineage leukemia) gene, was 631 bp away in a head-to-head orientation [12].
  • SCIP-1 shows antigenic and functional similarities to the human 18kDa complement inhibitor CD59 [21].

Analytical, diagnostic and therapeutic context of CDC42SE1

  • Using Northern blot analysis, three major SPEC1 mRNA transcripts of 1.6, 3.3, and 6.3 kb were detected [12].
  • We have examined this issue by studying SCIP expression in developing, degenerating, and regenerating rat peripheral nerves, and in Schwann cell-neuron cocultures [22].
  • High levels of SCIP mRNA were detected in developing and regenerating nerves, and axotomy at these times caused the level of SCIP mRNA to plummet [22].
  • Like SCIP-1, purified native paramyosin reacts with a polyclonal rabbit anti-human CD59 antiserum, as shown by Western blot analysis [23].
  • Fast protein liquid chromatography (FPLC) and affinity purification procedures for this sheep complement-inhibiting protein (SCIP) both yielded a pure protein with an apparent M(r) of 19,000 under reducing and non-reducing conditions [24].


  1. SPECs, small binding proteins for Cdc42. Pirone, D.M., Fukuhara, S., Gutkind, J.S., Burbelo, P.D. J. Biol. Chem. (2000) [Pubmed]
  2. The 3' untranslated regions of two related mRNAs contain an element highly repeated in the sea urchin genome. Carpenter, C.D., Bruskin, A.M., Spain, L.M., Eldon, E.D., Klein, W.H. Nucleic Acids Res. (1982) [Pubmed]
  3. Plastic phenotype of human oligodendroglial tumour cells in vitro. Tenenbaum, L., Teugels, E., Dogusan, Z., Avellana-Adalid, V., Hooghe-Peters, E.L. Neuropathol. Appl. Neurobiol. (1996) [Pubmed]
  4. Establishment and characterization of a human cell line from a serous papillary endometrial carcinoma. Boyd, J.A., Siegal, G.P., Kaufman, D.G. Gynecol. Oncol. (1989) [Pubmed]
  5. Treatment of male infertility due to spinal cord injury using rectal probe electroejaculation: the Israeli experience. Heruti, R.J., Katz, H., Menashe, Y., Weissenberg, R., Raviv, G., Madjar, I., Ohry, A. Spinal Cord (2001) [Pubmed]
  6. Novel proteins belonging to the troponin C superfamily are encoded by a set of mRNAs in sea urchin embryos. Carpenter, C.D., Bruskin, A.M., Hardin, P.E., Keast, M.J., Anstrom, J., Tyner, A.L., Brandhorst, B.P., Klein, W.H. Cell (1984) [Pubmed]
  7. Schwann cell differentiation. Zorick, T.S., Lemke, G. Curr. Opin. Cell Biol. (1996) [Pubmed]
  8. Intersecting batteries of differentially expressed genes in the early sea urchin embryo. Thiebaud, P., Goodstein, M., Calzone, F.J., Thézé, N., Britten, R.J., Davidson, E.H. Genes Dev. (1990) [Pubmed]
  9. Nab proteins are essential for peripheral nervous system myelination. Le, N., Nagarajan, R., Wang, J.Y., Svaren, J., LaPash, C., Araki, T., Schmidt, R.E., Milbrandt, J. Nat. Neurosci. (2005) [Pubmed]
  10. Frequency of the allelic variant (Trp8Arg/Ile15Thr) of the luteinizing hormone gene in a Brazilian cohort of healthy subjects and in patients with hypogonadotropic hypogonadism. Berger, K., Billerbeck, A.E., Costa, E.M., Carvalho, L.S., Arnhold, I.J., Mendonca, B.B. Clinics (São Paulo, Brazil) (2005) [Pubmed]
  11. Identification of a repeated sequence in the genome of the sea urchin which is transcribed by RNA polymerase III and contains the features of a retroposon. Nisson, P.E., Hickey, R.J., Boshar, M.F., Crain, W.R. Nucleic Acids Res. (1988) [Pubmed]
  12. The genomic structure of the human SPEC1 gene reveals complex splicing and close promoter proximity to the AF1q translocation gene. Pirone, D.M., Oberst, M.D., Stylianou, D., Burbelo, P.D. Gene (2001) [Pubmed]
  13. Tandem duplication and divergence of a sea urchin protein belonging to the troponin C superfamily. Xiang, M.Q., Bédard, P.A., Wessel, G., Filion, M., Brandhorst, B.P., Klein, W.H. J. Biol. Chem. (1988) [Pubmed]
  14. Biochemical characterization of distinct regions of SPEC molecules and their role in phagocytosis. Ching, K.H., Kisailus, A.E., Burbelo, P.D. Exp. Cell Res. (2007) [Pubmed]
  15. Temporal and spatial transcriptional regulation of the aboral ectoderm-specific Spec genes during sea urchin embryogenesis. Tomlinson, C.R., Klein, W.H. Mol. Reprod. Dev. (1990) [Pubmed]
  16. The role of SPECs, small Cdc42-binding proteins, in F-actin accumulation at the immunological synapse. Ching, K.H., Kisailus, A.E., Burbelo, P.D. J. Biol. Chem. (2005) [Pubmed]
  17. Repression of gonadotropin-releasing hormone promoter activity by the POU homeodomain transcription factor SCIP/Oct-6/Tst-1: a regulatory mechanism of phenotype expression? Wierman, M.E., Xiong, X., Kepa, J.K., Spaulding, A.J., Jacobsen, B.M., Fang, Z., Nilaver, G., Ojeda, S.R. Mol. Cell. Biol. (1997) [Pubmed]
  18. Resolution of two emission spectra for tryptophan using frequency-domain phase-modulation spectra. Lakowicz, J.R., Jayaweera, R., Szmacinski, H., Wiczk, W. Photochem. Photobiol. (1989) [Pubmed]
  19. Propoxyphene and norpropoxyphene quantitation in the same solid-phase extraction using Toxi-Lab Spec VC MP3 system. King, J.W., King, L.J. Journal of analytical toxicology. (1994) [Pubmed]
  20. Transcription of the Spec 1-like gene of Lytechinus is selectively inhibited in response to disruption of the extracellular matrix. Wessel, G.M., Zhang, W., Tomlinson, C.R., Lennarz, W.J., Klein, W.H. Development (1989) [Pubmed]
  21. Novel mechanisms of immune evasion by Schistosoma mansoni. Fishelson, Z. Mem. Inst. Oswaldo Cruz (1995) [Pubmed]
  22. Axons regulate Schwann cell expression of the POU transcription factor SCIP. Scherer, S.S., Wang, D.Y., Kuhn, R., Lemke, G., Wrabetz, L., Kamholz, J. J. Neurosci. (1994) [Pubmed]
  23. Inhibition of the complement membrane attack complex by Schistosoma mansoni paramyosin. Deng, J., Gold, D., LoVerde, P.T., Fishelson, Z. Infect. Immun. (2003) [Pubmed]
  24. The sheep analogue of human CD59: purification and characterization of its complement inhibitory activity. van den Berg, C.W., Harrison, R.A., Morgan, B.P. Immunology (1993) [Pubmed]
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