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Gene Review

HAP1  -  huntingtin-associated protein 1

Homo sapiens

Synonyms: HAP-1, HAP2, HIP5, HLP, HLP1, ...
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Disease relevance of HAP1


Psychiatry related information on HAP1


High impact information on HAP1


Chemical compound and disease context of HAP1

  • HAP1 [methyl 4-(2-chloro-4-fluorophenyl)-6-methyl-2-(pyridin-2-yl)-1,4-dihydropyrimidine-5-carboxylate], a heteroaryldihydropyrimidine, is a potent HBV capsid assembly activator and misdirector [5].

Biological context of HAP1

  • HAP1 (Human AP endonuclease 1), the major enzyme in human cells initiating repair of AP sites, shows strong sequence homology to DNA repair enzymes from bacteria, Drosophila and other mammalian species [11].
  • Ten promoter polymorphisms (9 previously unreported) displayed strong linkage disequilibrium, yielding identification of three frequently observed haplotypes [HAP1 (43%), HAP2 (36%), and HAP3 (8%)] [12].
  • However, other rare or common apoE phenotypes have been observed in patients with type III HLP [13].
  • Identification of a putative active site cysteine residue should facilitate analysis of the mechanism by which the HAP1 protein may alter the redox state of a wide range of transcription factors [3].
  • It is concluded that the HAP1 protein has evolved a novel redox activation domain capable of regulating the DNA binding activity of a proto-oncogene product which is not essential for its DNA repair functions [3].

Anatomical context of HAP1

  • Our study also demonstrates that mitochondrial genetic status plays a key role in regulation of a multifunctional protein APE1 (also known as Ref1 or HAP1) involved in transcription and DNA repair in the nucleus and the mitochondria [14].
  • Jun protein inactivated by oxidation of this residue can be efficiently reactivated by a factor from human cell nuclei, recently identified as a DNA repair enzyme (termed HAP1 or Ref-1) [3].
  • Stable HeLa cell transfectants expressing HAP1 antisense RNA were found to express greatly reduced levels of the HAP1 protein compared to equivalent sense orientation and vector-only control transfectants [4].
  • No tissue localisation of HAP1-like immunoreactivity was observed in normal ovarian surface epithelium [15].
  • Immunohistochemical localisation of HAP1-like activity was present in malignant ovarian epithelium and stroma but strong immunostaining was present in blood vessels, areas with myxomatous stroma and vascular spaces [15].

Associations of HAP1 with chemical compounds

  • Basal HAP3 reporter activity was significantly elevated (1.8-fold) but decreased to the same levels as HAP2 and HAP1 with increasing concentrations of sulforaphane, benzyl isothiocyanate (BITC), and epigallocatechin gallate (EGCG) [12].
  • The antisense HAP1 transfectants exhibited a normal growth rate, cell morphology and plating efficiency, but were hypersensitive to killing by a wide range of DNA damaging agents, including methyl methanesulphonate, hydrogen peroxide, menadione, and paraquat [4].
  • The ability of lucanthone to inhibit the normal repair of abasic sites might reflect inhibition of apurinic/apyrimidinic endonuclease (HAP1) by the drug, thereby preventing an early step in the base excision repair pathway [16].
  • Surprisingly, the NF-kappa B and HLP-1 binding activities were substantially inhibited in acyclovir-treated cells [17].
  • Of the male subjects with HLP 1/3-1/2 had a diabetic or borderline i.v. glucose tolerance [18].

Other interactions of HAP1


Analytical, diagnostic and therapeutic context of HAP1


  1. Nuclear localization of human AP endonuclease 1 (HAP1/Ref-1) associates with prognosis in early operable non-small cell lung cancer (NSCLC). Kakolyris, S., Giatromanolaki, A., Koukourakis, M., Kaklamanis, L., Kanavaros, P., Hickson, I.D., Barzilay, G., Georgoulias, V., Gatter, K.C., Harris, A.L. J. Pathol. (1999) [Pubmed]
  2. Human AP endonuclease 1 (HAP1) protein expression in breast cancer correlates with lymph node status and angiogenesis. Kakolyris, S., Kaklamanis, L., Engels, K., Fox, S.B., Taylor, M., Hickson, I.D., Gatter, K.C., Harris, A.L. Br. J. Cancer (1998) [Pubmed]
  3. Identification of residues in the human DNA repair enzyme HAP1 (Ref-1) that are essential for redox regulation of Jun DNA binding. Walker, L.J., Robson, C.N., Black, E., Gillespie, D., Hickson, I.D. Mol. Cell. Biol. (1993) [Pubmed]
  4. A role for the human DNA repair enzyme HAP1 in cellular protection against DNA damaging agents and hypoxic stress. Walker, L.J., Craig, R.B., Harris, A.L., Hickson, I.D. Nucleic Acids Res. (1994) [Pubmed]
  5. Global Structural Changes in Hepatitis B Virus Capsids Induced by the Assembly Effector HAP1. Bourne, C.R., Finn, M.G., Zlotnick, A. J. Virol. (2006) [Pubmed]
  6. Hypothalamic huntingtin-associated protein 1 as a mediator of feeding behavior. Sheng, G., Chang, G.Q., Lin, J.Y., Yu, Z.X., Fang, Z.H., Rong, J., Lipton, S.A., Li, S.H., Tong, G., Leibowitz, S.F., Li, X.J. Nat. Med. (2006) [Pubmed]
  7. Lithostathine quadruple-helical filaments form proteinase K-resistant deposits in Creutzfeldt-Jakob disease. Laurine, E., Grégoire, C., Fändrich, M., Engemann, S., Marchal, S., Thion, L., Mohr, M., Monsarrat, B., Michel, B., Dobson, C.M., Wanker, E., Erard, M., Verdier, J.M. J. Biol. Chem. (2003) [Pubmed]
  8. Heme binds to a short sequence that serves a regulatory function in diverse proteins. Zhang, L., Guarente, L. EMBO J. (1995) [Pubmed]
  9. Huntingtin-associated protein 1 regulates inhibitory synaptic transmission by modulating gamma-aminobutyric acid type A receptor membrane trafficking. Kittler, J.T., Thomas, P., Tretter, V., Bogdanov, Y.D., Haucke, V., Smart, T.G., Moss, S.J. Proc. Natl. Acad. Sci. U.S.A. (2004) [Pubmed]
  10. Huntingtin-associated protein 1 (HAP1) interacts with androgen receptor (AR) and suppresses SBMA-mutant-AR-induced apoptosis. Takeshita, Y., Fujinaga, R., Zhao, C., Yanai, A., Shinoda, K. Hum. Mol. Genet. (2006) [Pubmed]
  11. Structure of the human DNA repair gene HAP1 and its localisation to chromosome 14q 11.2-12. Robson, C.N., Hochhauser, D., Craig, R., Rack, K., Buckle, V.J., Hickson, I.D. Nucleic Acids Res. (1992) [Pubmed]
  12. Haplotype-environment interactions that regulate the human glutathione S-transferase P1 promoter. Cauchi, S., Han, W., Kumar, S.V., Spivack, S.D. Cancer Res. (2006) [Pubmed]
  13. Genetic polymorphism in human apolipoprotein E. Zannis, V.I. Meth. Enzymol. (1986) [Pubmed]
  14. Inter-genomic cross talk between mitochondria and the nucleus plays an important role in tumorigenesis. Singh, K.K., Kulawiec, M., Still, I., Desouki, M.M., Geradts, J., Matsui, S. Gene (2005) [Pubmed]
  15. Proteomic-based identification of haptoglobin-1 precursor as a novel circulating biomarker of ovarian cancer. Ahmed, N., Barker, G., Oliva, K.T., Hoffmann, P., Riley, C., Reeve, S., Smith, A.I., Kemp, B.E., Quinn, M.A., Rice, G.E. Br. J. Cancer (2004) [Pubmed]
  16. Abasic sites in DNA of HeLa cells induced by lucanthone. Mendez, F., Goldman, J.D., Bases, R.E. Cancer Invest. (2002) [Pubmed]
  17. Differential contribution of herpes simplex virus type 1 gene products and cellular factors to the activation of human immunodeficiency virus type 1 provirus. Vlach, J., Pitha, P.M. J. Virol. (1993) [Pubmed]
  18. Studies in asymptomatic primary hyperlipidaemia II. Clinical findings. Olsson, A.G. Acta medica Scandinavica. (1975) [Pubmed]
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