Prostaglandin receptor

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Prostaglandin receptors or Prostanoid receptors represent a sub-class of cell surface membrane receptors that are regarded as the primary receptors for one or more of the classical, naturally occurring prostanoids viz., prostaglandin D2, (i.e. PGD2), PGE2, PGF2alpha, prostacyclin (PGI2), thromboxane A2 (TXA2), and PGH2.[1] They are named based on the prostanoid to which they preferentially bind and respond, e.g. the receptor responsive to PGI2 at lower concentrations than any other prostanoid is named the Prostacyclin receptor (IP). One exception to this rule is the receptor for thromboxane A2 (TP) which binds and responds to PGH2 and TXA2 equally well.

All of the prostanoid receptors are G-protein-coupled receptors belonging to the Subfamily A14 of the rhodopsin-like receptor family except for the Prostaglandin DP2 receptor which is more closely related in amino acid sequence and functionality to chemotactic factor receptors such as the receptors for C5a and leukotriene B4.[2]

Prostanoid receptors bind and respond principally to metabolites of the straight chain polyunsaturated fatty acid (PUFA), arachidonic acid. These metabolites contain two double bonds and are named series 2 prostanoids, i.e. PGD2, PGE2, PGF2α, PGI2, TXA2 and PGH2. However, the same enzymes that metabolize arachidonic acid to series 2 prostanoids similarly metabolize two other straight chain PUFAs: they metabolize gamma-Linolenic acid, which has one less double bond than arachidonic acid, to series 1 prostanoids (PGD1, PGE1, etc.), which have one less double bond than the series 2 prostanoids, and they metabolize eicosapentaenoic acid, which has one more double bond than arachidonic acid, to series 3 prostanoids (PGD3, PGE3, etc.), which have one more double bond than the series 2 prostanoids. In general, receptors for the series 2 prostaonids also bind with and respond to the series 1 and 3 prostanoids. Typically, prosanoid receptors show somewhat less affinity and responsiveness to the 1 and 3 series prostanoids.[3]

There are 9 established prostanoid receptors. The following table gives these receptors': a) full name; b) shortened names; c) activating prostanoids (presented in order of decreasing potencies);[4] d) time-honored classification as contractile (i.e. conracting smooth muscle), relaxant (i.e. relaxing smooth muscle), or inhibitory (i.e. inhibiting adenyl cyclase (AC) production of cyclic AMP [cAMP]);[5] e) G proteins types to which they link and activate, i.e. those containing the Gs alpha subunit, Gi alpha subunit, Gq alpha subunit and/or G12 subunit;[2][4] and f) signaling pathways which they regulate including Adenyl cyclase which when activated increases cellular cAMP and when inhibited reduces the cellular levels of this secondary messenger; Phosphoinositide 3-kinase which when activated is responsible for forming phosphatidylinositol 3-phosphate, phosphatidylinositol (3,4)-bisphosphate, and phosphatidylinositol (3,4,5)-trisphosphate secondary messengers; Phospholipase C (PLC) which when activated is responsible for forming Inositol trisphosphate (IP3) and diacylglycerol secondary messengers that are, respectively, responsible for raising the levels of Ca2+ in the cellular cytosol to control the activity of Ca2+-cell signaling agents and for activating protein kinase C (PKC) secondary messengers; and Extracellular signal–regulated kinases (ERK), p38 mitogen-activated protein kinases (p38 Mpk), and cAMP response element-binding protein (CREB) which when activated phosphorylate and thereby influence the activity of key proteins that govern cell function.[2]

Full name shortened name activating prostanoids classification[5] G protein linkage[2] pathways[2]
Prostaglandin DP1 receptor DP1 PGD2>>PGE2>PGF2α>PGI2=TXA2[6] relaxant Gs alpha subunit activates AC, increases cAMP, raises Ca2+
Prostaglandin DP2 receptor DP2 PGD2>>PGF2α=PGE2>PGI2=TXA2[7]  ? Gi alpha subunit inhibits AC to depress cAMP levels
Prostaglandin EP1 receptor EP1 PGE2>PGF2α=PGI2>PGD2=TXA2[8] contractile Gq alpha subunit stimulates PLC, IP3, PKC, ERK, p38 Mpk, and CREB
Prostaglandin EP2 receptor EP2 PGE2>PGF2α=PGI2>PGD2=TXA2[9] relaxant Gs alpha subunit stimulates AC, raises cAMP, stimulates beta catenin and Glycogen synthase kinase 3
Prostaglandin EP3 receptor EP3 PGE2>PGF2α,PGI2>PGD2=TXA2[10] inhibitory Gi & G12 subunit inhibits AC, decreases cAMP, stimulates PLC & IP3, raises Ca2+
Prostaglandin EP4 receptor EP4 PGE2>PGF2α=PGI2>PGD2=TXA2[11] relaxant Gs alpha subunit stimulates AC, PKA, PI3K, AKT, ERK, p38 Mpk, & CREB; raises cAMP
Prostaglandin F2α receptor FP PGF2α>PGD2>PGE2>PGI2=TXA2[12] contractile Gq alpha subunit stimulates PLC, IP3, & PKC; raises Ca2+
Prostacyclin I2 receptor IP PGI2>>PGD2=PGE2=PGF2α>TXA2[13] relaxant Gs alpha subunit stimulates AC & PKA; raises cAMP
Thromboxane A2 receptor TP TXA=PGH2>>PGD2=PGE2=PGF2α=PGI2[14] contractile Gq alpha subunit stimulates PLC & IP3; raises Ca2+

There is indirect evidence for a second PGI2 receptor in BEAS-2B human airway epithelial cells but this finding has not been collaborated and the putative receptor has not been otherwise defined.[15]

See also[edit]

References[edit]

  1. ^ Tsuboi K, Sugimoto Y, Ichikawa A (2002). "Prostanoid receptor subtypes". Prostaglandins Other Lipid Mediat. 68-69: 535–56. doi:10.1016/S0090-6980(02)00054-0. PMID 12432942. 
  2. ^ a b c d e Moreno JJ (2016). "Eicosanoid receptors: Targets for the treatment of disrupted intestinal epithelial homeostasis". European Journal of Pharmacology. 796: 7–19. doi:10.1016/j.ejphar.2016.12.004. PMID 27940058. 
  3. ^ Narumiya S, Sugimoto Y, Ushikubi F (1999). "Prostanoid receptors: structures, properties, and functions". Physiological Reviews. 79 (4): 1193–226. PMID 10508233. 
  4. ^ a b http://www.guidetopharmacology.org/GRAC/FamilyDisplayForward?familyId=58
  5. ^ a b Matsuoka T, Narumiya S (2008). "The roles of prostanoids in infection and sickness behaviors". Journal of Infection and Chemotherapy : Official Journal of the Japan Society of Chemotherapy. 14 (4): 270–8. doi:10.1007/s10156-008-0622-3. PMID 18709530. 
  6. ^ http://www.guidetopharmacology.org/GRAC/ObjectDisplayForward?objectId=338&familyId=58&familyType=GPCR
  7. ^ http://www.guidetopharmacology.org/GRAC/ObjectDisplayForward?objectId=339&familyId=58&familyType=GPCR
  8. ^ http://www.guidetopharmacology.org/GRAC/ObjectDisplayForward?objectId=340&familyId=58&familyType=GPCR
  9. ^ http://www.guidetopharmacology.org/GRAC/ObjectDisplayForward?objectId=341&familyId=58&familyType=GPCR
  10. ^ http://www.guidetopharmacology.org/GRAC/ObjectDisplayForward?objectId=342&familyId=58&familyType=GPCR
  11. ^ http://www.guidetopharmacology.org/GRAC/ObjectDisplayForward?objectId=343&familyId=58&familyType=GPCR
  12. ^ http://www.guidetopharmacology.org/GRAC/ObjectDisplayForward?objectId=344&familyId=58&familyType=GPCR
  13. ^ http://www.guidetopharmacology.org/GRAC/ObjectDisplayForward?objectId=345&familyId=58&familyType=GPCR
  14. ^ http://www.guidetopharmacology.org/GRAC/ObjectDisplayForward?objectId=346&familyId=58&familyType=GPCR
  15. ^ Wilson SM, Sheddan NA, Newton R, Giembycz MA (2011). "Evidence for a second receptor for prostacyclin on human airway epithelial cells that mediates inhibition of CXCL9 and CXCL10 release". Molecular Pharmacology. 79 (3): 586–95. doi:10.1124/mol.110.069674. PMID 21173040. 

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