Biology:OGFr

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Short description: Protein


A representation of the 3D structure of the protein myoglobin showing turquoise α-helices.
Generic protein structure example
Opioid growth factor receptor (OGFr) conserved region
Identifiers
SymbolOGFr_N
PfamPF04664
InterProIPR006757
Opioid growth factor receptor repeat
Identifiers
SymbolOGFr_III
PfamPF04680
InterProIPR006770

Opioid growth factor receptor, also known as OGFr or the ζ-opioid receptor, is a protein which in humans is encoded by the OGFR gene.[1][2] The protein encoded by this gene is a receptor for opioid growth factor (OGF), also known as [Met(5)]-enkephalin. The endogenous ligand is thus a known opioid peptide, and OGFr was originally discovered and named as a new opioid receptor zeta (ζ). However it was subsequently found that it shares little sequence similarity with the other opioid receptors, and has quite different function.

Function

The natural function of this receptor appears to be in regulation of tissue growth,[3][4][5][6] and it has been shown to be important in embryonic development,[7] wound repair,[8] and certain forms of cancer.[9][10][11][12]

OGF is a negative regulator of cell proliferation and tissue organization in a variety of processes. The encoded unbound receptor for OGF has been localized to the outer nuclear envelope, where it binds OGF and is translocated into the nucleus. The coding sequence of this gene contains a polymorphic region of 60 nt tandem imperfect repeat units. Several transcripts containing between zero and eight repeat units have been reported.[1]

Mechanism of activation

The opioid growth factor receptor consists of a chain of 677 amino acids, which includes a nuclear localization sequence region. When OGF binds to the receptor, an OGF-OGFr complex is formed, which leads to the increase in the synthesis of the selective cyclin-dependent kinase (CDK) inhibitor proteins, p12 and p16. Retinoblastoma protein becomes inactivated through phosphorylation by CDKs, and leads to the progression of the cell cycle from the G1 phase to the S phase. Because the activation of the OGF receptor, blocks the phosphorylation of retinoblastoma proteins, retardation of the G1 phase occurs, which prevents the cell from further dividing.[13][14]

Therapeutic applications

Upregulation of OGFr and consequent stimulation of the OGF-OGFr system are important for the anti-proliferative effects of imidazoquinoline drugs like imiquimod and resiquimod, which are immune response modifiers with potent antiviral and antitumour effects, used as topical creams for the treatment of skin cancers and warts.[15]

Structure

OGF contains a conserved N-terminal domain followed by a series of imperfect repeats.[4]

References

  1. 1.0 1.1 "Entrez Gene: OGFR opioid growth factor receptor". https://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=11054. 
  2. "Cloning, sequencing, chromosomal location, and function of cDNAs encoding an opioid growth factor receptor (OGFr) in humans". Brain Res. 856 (1–2): 75–83. February 2000. doi:10.1016/S0006-8993(99)02330-6. PMID 10677613. 
  3. "Ontogeny of the opioid growth factor, Met5-enkephalin, preproenkephalin gene expression, and the zeta opioid receptor in the developing and adult aorta of rat". Dev. Dyn. 211 (4): 327–37. April 1998. doi:10.1002/(SICI)1097-0177(199804)211:4<327::AID-AJA4>3.0.CO;2-J. PMID 9566952. 
  4. 4.0 4.1 "The biology of the opioid growth factor receptor (OGFr)". Brain Res. Brain Res. Rev. 38 (3): 351–76. February 2002. doi:10.1016/S0165-0173(01)00160-6. PMID 11890982. 
  5. "Effects of met-enkephalin on cell proliferation in different models of adrenocortical-cell growth". Int. J. Mol. Med. 15 (5): 841–5. May 2005. doi:10.3892/ijmm.15.5.841. PMID 15806307. 
  6. "The OGF-OGFr axis utilizes the p16INK4a and p21WAF1/CIP1 pathways to restrict normal cell proliferation". Molecular Biology of the Cell 20 (1): 319–27. January 2009. doi:10.1091/mbc.E08-07-0681. PMID 18923142. 
  7. "Opioid growth factor and organ development in rat and human embryos". Brain Res. 839 (2): 313–22. August 1999. doi:10.1016/S0006-8993(99)01753-9. PMID 10519055. 
  8. "Opioid growth factor modulation of corneal epithelium: uppers and downers". Curr. Eye Res. 26 (5): 249–62. May 2003. doi:10.1076/ceyr.26.4.249.15427. PMID 12854052. 
  9. "Human pancreatic cancer cell proliferation in tissue culture is tonically inhibited by opioid growth factor". Int. J. Oncol. 14 (3): 577–84. March 1999. doi:10.3892/ijo.14.3.577. PMID 10024694. 
  10. "Regulation of human head and neck squamous cell carcinoma growth in tissue culture by opioid growth factor". Int. J. Oncol. 14 (5): 991–8. May 1999. doi:10.3892/ijo.14.5.991. PMID 10200353. 
  11. "The opioid growth factor (OGF)-OGF receptor axis uses the p16 pathway to inhibit head and neck cancer". Cancer Research 67 (21): 10511–8. November 2007. doi:10.1158/0008-5472.CAN-07-1922. PMID 17974995. 
  12. "Cell Proliferation of Human Ovarian Cancer is Regulated by the Opioid Growth Factor - Opioid Growth Factor Receptor Axis". American Journal of Physiology. Regulatory, Integrative and Comparative Physiology 296 (6): R1716–25. March 2009. doi:10.1152/ajpregu.00075.2009. PMID 19297547. 
  13. "Opioid growth factor-opioid growth factor receptor axis is a physiological determinant of cell proliferation in diverse human cancers". American Journal of Physiology. Regulatory, Integrative and Comparative Physiology 297 (4): R1154–61. 2009. doi:10.1152/ajpregu.00414.2009. PMID 19675283. 
  14. "The opioid growth factor-opioid growth factor receptor axis regulates cell proliferation of human hepatocellular cancer". American Journal of Physiology. Regulatory, Integrative and Comparative Physiology 298 (2): R459–66. 2010. doi:10.1152/ajpregu.00646.2009. PMID 19923357. 
  15. "Imiquimod upregulates the opioid growth factor receptor to inhibit cell proliferation independent of immune function". Experimental Biology and Medicine 233 (8): 968–79. August 2008. doi:10.3181/0802-RM-58. PMID 18480416. 

Further reading

This article incorporates text from the public domain Pfam and InterPro: IPR006757
This article incorporates text from the public domain Pfam and InterPro: IPR006770