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Yerushalmi GM, Shuraki B, Yung Y, Maman E, Baum M, Hennebold JD, Adashi EY, Hourvitz A. ABCC4 is a PGE2 efflux transporter in the ovarian follicle: A mediator of ovulation and a potential non-hormonal contraceptive target. FASEB J 2023; 37:e22858. [PMID: 36943419 DOI: 10.1096/fj.202101931rr] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 01/12/2023] [Accepted: 02/22/2023] [Indexed: 03/23/2023]
Abstract
The role of prostaglandins (PGs) in the ovulatory process is known. However, the role of the ATP binding cassette subfamily C member 4 (ABCC4), transmembrane PG carrier protein, in ovulation remains unknown. We report herein that ABCC4 expression is significantly upregulated in preovulatory human granulosa cells (GCs). We found that PGE2 efflux in cultured human GCs is mediated by ABCC4 thus regulating its extracellular concentration. The ABCC4 inhibitor probenecid demonstrated effective blocking of ovulation and affects key ovulatory genes in female mice in vivo. We postulate that the reduction in PGE2 efflux caused by the inhibition of ABCC4 activity in GCs decreases the extracellular concentration of PGE2 and its ovulatory effect. Treatment of female mice with low dose of probenecid as well as with the PTGS inhibitor indomethacin or Meloxicam synergistically blocks ovulation. These results support the hypothesis that ABCC4 has an important role in ovulation and might be a potential target for non-hormonal contraception, especially in combination with PGE2 synthesis inhibitors. These findings may fill the gap in understanding the role of ABCC4 in PGE2 signaling, enhance the understanding of ovulatory disorders, and facilitate the treatment and control of fertility.
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Affiliation(s)
- Gil M Yerushalmi
- Reproduction Laboratory and IVF Unit, Department of Obstetrics and Gynecology, Chaim Sheba Medical Center (affiliated with the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv), Tel Hashomer, Israel
- IVF Unit, Department of Obstetrics and Gynecology, The Yitzhak Shamir Medical Center (formerly Assaf Harofeh Medical Center) (affiliated with the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv), Zerifin, Israel
| | - Batel Shuraki
- Reproduction Laboratory and IVF Unit, Department of Obstetrics and Gynecology, Chaim Sheba Medical Center (affiliated with the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv), Tel Hashomer, Israel
| | - Yuval Yung
- Reproduction Laboratory and IVF Unit, Department of Obstetrics and Gynecology, Chaim Sheba Medical Center (affiliated with the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv), Tel Hashomer, Israel
| | - Ettie Maman
- Reproduction Laboratory and IVF Unit, Department of Obstetrics and Gynecology, Chaim Sheba Medical Center (affiliated with the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv), Tel Hashomer, Israel
| | - Micha Baum
- Reproduction Laboratory and IVF Unit, Department of Obstetrics and Gynecology, Chaim Sheba Medical Center (affiliated with the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv), Tel Hashomer, Israel
| | - Jon D Hennebold
- Division of Reproductive & Developmental Sciences, Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, Oregon, USA
| | - Eli Y Adashi
- Department of Medical Science and Obstetrics and Gynecology, the Warren Alpert Medical School, Brown University, Providence, Rhode Island, USA
- Department of Obstetrics and Gynecology, the Warren Alpert Medical School, Brown University, Providence, Rhode Island, USA
| | - Ariel Hourvitz
- Reproduction Laboratory and IVF Unit, Department of Obstetrics and Gynecology, Chaim Sheba Medical Center (affiliated with the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv), Tel Hashomer, Israel
- IVF Unit, Department of Obstetrics and Gynecology, The Yitzhak Shamir Medical Center (formerly Assaf Harofeh Medical Center) (affiliated with the Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv), Zerifin, Israel
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Auranofin: Past to Present, and repurposing. Int Immunopharmacol 2021; 101:108272. [PMID: 34731781 DOI: 10.1016/j.intimp.2021.108272] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Revised: 10/09/2021] [Accepted: 10/12/2021] [Indexed: 01/15/2023]
Abstract
Auranofin (AF), a gold compound, has been used to treat rheumatoid arthritis (RA) for more than 40 years; however, its mechanism of action remains unknown. We revealed that AF inhibited the induction of proinflammatory proteins and their mRNAs by the inflammatory stimulants, cyclooxygenase-2 and inducible nitric oxide synthase, and their upstream regulator, NF-κB. AF also activated the proteins peroxyredoxin-1, Kelch-like ECH-associated protein 1, and NF-E2-related factor 2, and inhibited thioredoxin reductase, all of which are involved in oxidative or electrophilic stress under physiological conditions. Although the cell membrane was previously considered to be permeable to AF because of its hydrophobicity, the mechanisms responsible for transporting AF into and out of cells as well as its effects on the uptake and excretion of other drugs have not yet been elucidated. Antibodies for cytokines have recently been employed in the treatment of RA, which has had an impact on the use of AF. Trials to repurpose AF as a risk-controlled agent to treat cancers or infectious diseases, including severe acute respiratory syndrome coronavirus 2/coronavirus disease 2019, are ongoing. Novel gold compounds are also under development as anti-cancer and anti-infection agents.
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Nakanishi T, Nakamura Y, Umeno J. Recent advances in studies of SLCO2A1 as a key regulator of the delivery of prostaglandins to their sites of action. Pharmacol Ther 2021; 223:107803. [PMID: 33465398 DOI: 10.1016/j.pharmthera.2021.107803] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 12/18/2020] [Indexed: 02/08/2023]
Abstract
Solute carrier organic anion transporter family member 2A1 (SLCO2A1, also known as PGT, OATP2A1, PHOAR2, or SLC21A2) is a plasma membrane transporter consisting of 12 transmembrane domains. It is ubiquitously expressed in tissues, and mediates the membrane transport of prostaglandins (PGs, mainly PGE2, PGF2α, PGD2) and thromboxanes (e.g., TxB2). SLCO2A1-mediated transport is electrogenic and is facilitated by an outwardly directed gradient of lactate. PGs imported by SLCO2A1 are rapidly oxidized by cytoplasmic 15-hydroxyprostaglandin dehydrogenase (15-PGDH, encoded by HPGD). Accumulated evidence suggests that SLCO2A1 plays critical roles in many physiological processes in mammals, and it is considered a potential pharmacological target for diabetic foot ulcer treatment, antipyresis, and non-hormonal contraception. Furthermore, whole-exome analyses suggest that recessive inheritance of SLCO2A1 mutations is associated with two refractory diseases, primary hypertrophic osteoarthropathy (PHO) and chronic enteropathy associated with SLCO2A1 (CEAS). Intriguingly, SLCO2A1 is also a key component of the Maxi-Cl channel, which regulates fluxes of inorganic and organic anions, including ATP. Further study of the bimodal function of SLCO2A1 as a transporter and ion channel is expected to throw new light on the complex pathology of human diseases. Here, we review and summarize recent information on the molecular functions of SLCO2A1, and we discuss its pathophysiological significance.
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Affiliation(s)
- Takeo Nakanishi
- Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki, Gunma 370-0033, Japan.
| | - Yoshinobu Nakamura
- Faculty of Pharmacy, Takasaki University of Health and Welfare, Takasaki, Gunma 370-0033, Japan
| | - Junji Umeno
- Department of Medicine and Clinical Science, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Fukuoka 812-8582, Japan
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Seo MJ, Oh DK. Prostaglandin synthases: Molecular characterization and involvement in prostaglandin biosynthesis. Prog Lipid Res 2017; 66:50-68. [DOI: 10.1016/j.plipres.2017.04.003] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 03/30/2017] [Accepted: 04/01/2017] [Indexed: 01/30/2023]
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Two novel mutations in the SLCO2A1 gene in a Chinese patient with primary hypertrophic osteoarthropathy. Gene 2013; 534:421-3. [PMID: 24185079 DOI: 10.1016/j.gene.2013.10.051] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2013] [Revised: 09/19/2013] [Accepted: 10/24/2013] [Indexed: 11/23/2022]
Abstract
Primary hypertrophic osteoarthropathy (PHO) is a rare monogenetic disease characterized by digital clubbing, periostosis and pachydermia. Mutations in the 15-hydroxy-prostaglandin dehydrogenase (HPGD) gene and solute carrier organic anion transporter family member 2A1 (SLCO2A1) gene have been shown to be associated with PHO. Here, we described clinical characteristics in a Chinese patient with PHO, and identified two novel mutations in SLCO2A1: a heterozygous guanine-to-thymidine transition at the invariant -1 position of the acceptor site of intron 2 (c.235-1G>T) and a heterozygous missense mutation p.Pro219Leu (c.656C>T) in exon 5.
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Zhang Z, He JW, Fu WZ, Zhang CQ, Zhang ZL. A novel mutation in the SLCO2A1 gene in a Chinese family with primary hypertrophic osteoarthropathy. Gene 2013; 521:191-4. [PMID: 23531451 DOI: 10.1016/j.gene.2013.03.047] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2013] [Revised: 02/26/2013] [Accepted: 03/02/2013] [Indexed: 11/25/2022]
Abstract
Primary hypertrophic osteoarthropathy (PHO) is a rare monogenetic disease that closely mimics hypertrophic osteoarthropathy secondary to pulmonary or other pathology. The study of PHO provides an opportunity to understand both the pathogenesis of hypertrophic osteoarthropathy and the functions of the underlying genes. PHO is characterized by digital clubbing, periostosis and pachydermia. Two genes are known to be related to PHO: SLCO2A1 and HPGD. Here, we identified a recurrent heterozygous guanine-to-adenine transition at the invariant +1 position of the donor site of intron 7 (c.940+1G>A) and a novel heterozygous missense mutation p.Asn534Lys (c.1602C>A) in exon 11 of SLCO2A1 in a Chinese young man with PHO. Identification of a novel genotype in PHO will provide clues to the phenotype-genotype relations and may assist not only in the clinical diagnosis of PHO but also in the interpretation of genetic information used for prenatal diagnosis and genetic counseling.
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Affiliation(s)
- Zeng Zhang
- Metabolic Bone Disease and Genetic Research Unit, Department of Osteoporosis and Bone Diseases, Shanghai Jiao Tong University Affliated the Sixth People's Hospital, Shanghai 200233, 600 Yi-Shan Rd., PR China
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Mutations in the prostaglandin transporter SLCO2A1 cause primary hypertrophic osteoarthropathy with digital clubbing. J Invest Dermatol 2012; 132:2473-2476. [PMID: 22696055 DOI: 10.1038/jid.2012.146] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Diggle CP, Parry DA, Logan CV, Laissue P, Rivera C, Restrepo CM, Fonseca DJ, Morgan JE, Allanore Y, Fontenay M, Wipff J, Varret M, Gibault L, Dalantaeva N, Korbonits M, Zhou B, Yuan G, Harifi G, Cefle K, Palanduz S, Akoglu H, Zwijnenburg PJ, Lichtenbelt KD, Aubry-Rozier B, Superti-Furga A, Dallapiccola B, Accadia M, Brancati F, Sheridan EG, Taylor GR, Carr IM, Johnson CA, Markham AF, Bonthron DT. Prostaglandin transporter mutations cause pachydermoperiostosis with myelofibrosis. Hum Mutat 2012; 33:1175-81. [PMID: 22553128 DOI: 10.1002/humu.22111] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 04/23/2012] [Indexed: 11/07/2022]
Abstract
Pachydermoperiostosis, or primary hypertrophic osteoarthropathy (PHO), is an inherited multisystem disorder, whose features closely mimic the reactive osteoarthropathy that commonly accompanies neoplastic and inflammatory pathologies. We previously described deficiency of the prostaglandin-degrading enzyme 15-hydroxyprostaglandin dehydrogenase (HPGD) as a cause of this condition, implicating elevated circulating prostaglandin E(2) (PGE(2)) as causative of PHO, and perhaps also as the principal mediator of secondary HO. However, PHO is genetically heterogeneous. Here, we use whole-exome sequencing to identify recessive mutations of the prostaglandin transporter SLCO2A1, in individuals lacking HPGD mutations. We performed exome sequencing of four probands with severe PHO, followed by conventional mutation analysis of SLCO2A1 in nine others. Biallelic SLCO2A1 mutations were identified in 12 of the 13 families. Affected individuals had elevated urinary PGE(2), but unlike HPGD-deficient patients, also excreted considerable quantities of the PGE(2) metabolite, PGE-M. Clinical differences between the two groups were also identified, notably that SLCO2A1-deficient individuals have a high frequency of severe anemia due to myelofibrosis. These findings reinforce the key role of systemic or local prostaglandin excess as the stimulus to HO. They also suggest that the induction or maintenance of hematopoietic stem cells by prostaglandin may depend upon transporter activity.
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Syeda MM, Jing X, Mirza RH, Yu H, Sellers RS, Chi Y. Prostaglandin transporter modulates wound healing in diabetes by regulating prostaglandin-induced angiogenesis. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 181:334-46. [PMID: 22609345 DOI: 10.1016/j.ajpath.2012.03.012] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2011] [Revised: 03/13/2012] [Accepted: 03/15/2012] [Indexed: 01/22/2023]
Abstract
Prostaglandin transporter (PGT) mediates prostaglandin (PG) catabolism and PG signal termination. The prostanoid PGE(2), which induces angiogenesis and vasodilation, is diminished in diabetic skin, suggesting that PGT up-regulation could be important in wound healing deficiency, typified by diabetic foot ulcer. We hypothesized that up-regulation of PGT in hyperglycemia could contribute to weakened PGE(2) signaling, leading to impaired angiogenesis and wound healing. In human dermal microvascular endothelial cells (HDMECs), exposure to hyperglycemia increased PGT expression and activity up to threefold, accompanied by reduced levels of PGE(2). Hyperglycemia reduced HDMEC migration by 50% and abolished tube formation. Deficits in PGE(2) expression, HDMEC migration, and tube formation could be corrected by treatment with the PGT inhibitor T26A, consistent with the idea that PGT hyperactivity is responsible for impairments in angiogenesis mediated by PG signaling. In vivo, PGT expression was profoundly induced in diabetes and by wounding, correlating with diminished levels of proangiogenic factors PGE(2) and VEGF in cutaneous wounds of diabetic mice. Pharmacological inhibition of PGT corrected these deficits. PGT inhibition shortened cutaneous wound closure time in diabetic mice from 22 to 16 days. This effect was associated with increased proliferation, re-epithelialization, neovascularization, and blood flow. These data provide evidence that hyperglycemia enhances PGT expression and activity, leading to diminished angiogenic signaling, a possible key mechanism underlying defective wound healing in diabetes.
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Affiliation(s)
- Mahrukh M Syeda
- Department of Medicine, Albert Einstein College of Medicine, New York City, NY 10461, USA
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Van Poucke M, Melkebeek V, Erkens T, Van Zeveren A, Cox E, Peelman LJ. Molecular cloning and characterization of the porcine prostaglandin transporter (SLCO2A1): evaluation of its role in F4 mediated neonatal diarrhoea. BMC Genet 2009; 10:64. [PMID: 19807916 PMCID: PMC2763009 DOI: 10.1186/1471-2156-10-64] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2009] [Accepted: 10/06/2009] [Indexed: 01/22/2023] Open
Abstract
Background Because prostaglandins are involved in many (patho)physiological processes, SLCO2A1 was already characterized in several species in an attempt to unravel specific processes/deficiencies. Here, we describe the molecular cloning and characterization of the porcine ortholog in order to evaluate its possible involvement in F4 enterotoxigenic E. coli mediated neonatal diarrhoea, based on a positional candidate gene approach study. Results Porcine SLCO2A1 is organized in 14 exons, containing an open reading frame of 1935 bp, encoding a 12-transmembrane organic anion cell surface transporter of 644 aa. The -388 to -5 upstream region comprises a (CpG)48 island containing a number of conserved promoter elements, including a TATA box. A potential alternative promoter region was found in the conserved -973 to -700 upstream region. No consensus polyadenylation signal was discovered in the 3' UTR. Repeat sequences were found in 15% of all the non coding sequences. As expected for a multifunctional protein, a wide tissue distribution was observed. mRNA expression was found in the adrenal gland, bladder, caecum, colon (centripetal coil/centrifugal coil), diaphragm, duodenum, gallbladder, heart, ileum, jejunum, kidney, liver, longissimus dorsi muscle, lung, lymph node, mesenterium, rectum, spleen, stomach, tongue and ureter, but not in the aorta, oesophagus and pancreas. The promoter region and the exons (including the splice sites) of SLCO2A1 were resequenced in 5 F4ab/ac receptor positive and 5 F4ab/ac receptor negative pigs. Two silent and 2 missense (both S → L at position 360 and 633) mutations were found, but none was associated with the F4ab/ac receptor phenotype. In addition, no phenotype associated differential mRNA expression or alternative/abberant splicing/polyadenylation was found in the jejunum. Conclusion The molecular cloning and characterization of porcine SLCO2A1 not only contributes to the already existing knowledge about the transporter in general, but enables studies on porcine prostaglandin related processes/deficiencies as patient and/or model. Here we examined its possible involvement as receptor in F4 enterotoxigenic E. coli mediated neonatal diarrhoea. Because no phenotype associated differences could be found in the gene sequence nor in its jejunal transcription profile of F4ab/ac receptor positive/negative pigs, SLCO2A1 can most likely be excluded as receptor for F4 bacteria.
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Affiliation(s)
- Mario Van Poucke
- Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium.
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Ivanov AI, Scheck AC, Romanovsky AA. Expression of genes controlling transport and catabolism of prostaglandin E2 in lipopolysaccharide fever. Am J Physiol Regul Integr Comp Physiol 2003; 284:R698-706. [PMID: 12399253 DOI: 10.1152/ajpregu.00570.2002] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Prostaglandin (PG) E(2) is a principal downstream mediator of fever and other symptoms of systemic inflammation. Its inactivation occurs in peripheral tissues, primarily the lungs and liver, via carrier-mediated cellular uptake and enzymatic oxidation. We hypothesized that inactivation of PGE(2) is suppressed during LPS fever and that transcriptional downregulation of PGE(2) carriers and catabolizing enzymes contributes to this suppression. Fever was induced in inbred Wistar-Kyoto rats by intravenous LPS (50 microg/kg); the controls received saline. Samples of the liver, lungs, and hypothalamus were harvested 0, 0.5, 1.5, and 5 h postinjection. The expression of the two principal transmembrane PGE(2) carriers (PG transporter and multispecific organic anion transporter) and the two key PGE(2)-inactivating enzymes [15-hydroxy-PG dehydrogenase (15-PGDH) and carbonyl reductase] was quantified by RT-PCR. All four genes of interest were downregulated in peripheral tissues (but not the brain) during fever. Most remarkably, the expression of hepatic 15-PGDH was decreased 26-fold 5 h post-LPS, whereas expression of pulmonary 15-PGDH was downregulated (as much as 18-fold) throughout the entire febrile course. The transcriptional downregulation of several proteins involved in PGE(2) inactivation, first reported here, is an unrecognized mechanism of systemic inflammation. By increasing the blood-brain gradient of PGE(2), this mechanism likely facilitates penetration of PGE(2) into the brain and prevents its elimination from the brain.
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Affiliation(s)
- Andrei I Ivanov
- Trauma Research and Neurology Research, Barrow Neurological Institute, St. Joseph's Hospital and Medical Center, Phoenix, Arizona 85013, USA
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Abstract
Newly synthesized prostaglandins (PGs) efflux from cells by simple diffusion, driven by pH and the membrane potential. Metabolic clearance requires energy-dependent uptake across the plasma membrane, followed by cytoplasmic oxidation. Several PG carriers have been cloned and characterized. PGT is broadly expressed in cyclooxygenase (COX)-positive cells, appears to be a lactate/PG exchanger, and is coordinately regulated with COX. By analogy with neurotransmitter release and re-uptake, PGT may regulate pericellular PG levels via re-uptake. PGT may also direct PGs towards and/or away from specific sets of PG receptors. Other members of the OATP transporter family also catalyze PG uptake; these are variably expressed and have variable affinities for PGs. The OATs are alpha-ketoglutarate/organic anion exchangers that accept PGs; these probably represent the uptake step in renal and hepatic PG degradation and excretion. Finally, certain glutathione-conjugated leukotrienes and PGs are actively extruded from cells by the MRPs; these may also play a role in metabolic clearance of PGs.
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Affiliation(s)
- Victor L Schuster
- Departments of Medicine and Physiology & Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
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Bao Y, Pucci ML, Chan BS, Lu R, Ito S, Schuster VL. Prostaglandin transporter PGT is expressed in cell types that synthesize and release prostanoids. Am J Physiol Renal Physiol 2002; 282:F1103-10. [PMID: 11997327 DOI: 10.1152/ajprenal.00152.2001] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
PGT is a broadly expressed transporter of prostaglandins (PGs) and thromboxane that is energetically poised to take up prostanoids across the plasma membrane. To gain insight into the function of PGT, we generated mouse monoclonal antibody 20 against a portion of putative extracellular loop 5 of rat PGT. Immunoblots of endogenous PGT in rat kidney revealed a 65-kDa protein in a zonal pattern corresponding to PG synthesis rates (papilla congruent with medulla > cortex). Immunocytochemically, PGT in rat kidneys was expressed in glomerular endothelial and mesangial cells, arteriolar endothelial and muscularis cells, principal cells of the collecting duct, medullary interstitial cells, medullary vasa rectae endothelia, and papillary surface epithelium. Proximal tubules, which are known to take up and metabolize PGs, were negative. Immunoblotting and immunocytochemistry revealed that rat platelets also express abundant PGT. Coexpression of the PG synthesis apparatus (cyclooxygenase) and PGT by the same cell suggests that prostanoids may undergo release and reuptake.
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Affiliation(s)
- Yi Bao
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Guo GL, Staudinger J, Ogura K, Klaassen CD. Induction of rat organic anion transporting polypeptide 2 by pregnenolone-16alpha-carbonitrile is via interaction with pregnane X receptor. Mol Pharmacol 2002; 61:832-9. [PMID: 11901222 DOI: 10.1124/mol.61.4.832] [Citation(s) in RCA: 103] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The rat organic anion transporting polypeptide 2 (oatp2; Slc21a5) is a liver transporter that mediates the uptake of a variety of structurally diverse compounds, and has a high affinity for cardiac glycosides. Treatment of rats with pregnenolone-16alpha-carbonitrile (PCN), a ligand for the rodent pregnane X receptor (PXR), significantly enhances the rat oatp2 gene expression. To understand the molecular mechanism of oatp2 induction by PCN, rat oatp2 gene was cloned. The rat oatp2 gene consists of 16 exons; alternative splicing of the second noncoding exon gives rise to the two published rat oatp2 cDNAs. Approximately 8700 base pairs (bp) of the 5'-flanking region of the rat oatp2 gene were linked to the luciferase reporter gene and used in transient transfection assays in H4IIE cells. Treatment of PCN induced the expression of the reporter gene in a dose-dependent manner. Four potential PXR response elements (PXREs) were identified in the 5'-flanking region of the rat oatp2 gene. One element (DR3-1) is located approximately -5000 bp with three more (DR3-2, DR3-3, and DR3-4) clustered at about -8000 bp. Results from electrophoretic mobility shift assays showed that the PXR-retinoid X receptor alpha heterodimer binds to the DR3-2 with the highest affinity, to the DR3-4 and DR3-1 with a lower affinity, and weakly or not at all to the DR3-3. Furthermore, a series of partial deletions of the 5'-flanking region illustrated that both the proximal and distal clusters of PXREs are required for maximal induction of rat oatp2 by PCN. In conclusion, these data elucidate the molecular mechanism by which PCN treatment induces rat oatp2 gene expression. In addition, this study identifies rat oatp2 as a direct PXR-targeted gene and further supports the hypothesis that activation of PXR affects a network of genes that is involved in either metabolism or transport of drugs, steroids, and bile acids.
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Affiliation(s)
- Grace L Guo
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas 66045-7417, USA
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Vezza R, Rokach J, FitzGerald GA. Prostaglandin F(2alpha) receptor-dependent regulation of prostaglandin transport. Mol Pharmacol 2001; 59:1506-13. [PMID: 11353812 DOI: 10.1124/mol.59.6.1506] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Prostaglandin (PG) F(2alpha) may act on its G protein-coupled receptor (FP) or be imported intracellularly via a transporter, which has high affinity for PGF(2alpha) and PGE(2), but not prostacyclin (PGI(2)). In cells overexpressing the epitope-tagged FP together with the human prostaglandin transporter (hPGT), stimulation of the FP with PGF(2alpha) (1 nM-1 microM), or the less potent FP agonist, the isoprostane 8,12-iso-iPF(2alpha)-III, inhibited prostaglandin uptake via the hPGT. This effect was abolished by pretreatment of the cells with cholera toxin, but not with pertussis toxin. Furthermore, two dominant negative constructs directed against Galpha(s) partially blocked FP-mediated regulation of hPGT function, also suggesting Galpha(s) involvement in this phenomenon. Surprisingly, neither an activator (dibutyryl cyclic AMP) nor an inhibitor (H89) of cyclic AMP-dependent protein kinase had any effect on FP-mediated inhibition of hPGT activity. Furthermore, although PGF(2alpha) increases intracellular cyclic AMP via Galpha(s) activation, it does not induce phosphorylation of the transporter, excluding a role of cyclic AMP-dependent protein kinase in hPGT regulation. Activation of the PGI(2) receptor, which is also coupled to Galpha(s), does not regulate hPGT activity, despite markedly augmenting adenylate cyclase activation. In conclusion, activation of the FP reduces intracellular import of prostaglandins for metabolic inactivation, increasing prostanoid availability for membrane receptor activation. This effect seems to be mediated via Galpha(s), independent of adenylate cyclase and cyclic AMP-dependent protein kinase activation.
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Affiliation(s)
- R Vezza
- Center for Experimental Therapeutics, University of Pennsylvania, 153 Johnson Pavilion, 3600 Hamilton Walk, Philadelphia, PA 19104, USA
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Ogura K, Choudhuri S, Klaassen CD. Genomic organization and tissue-specific expression of splice variants of mouse organic anion transporting polypeptide 2. Biochem Biophys Res Commun 2001; 281:431-9. [PMID: 11181066 DOI: 10.1006/bbrc.2001.4387] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
cDNAs that code for mouse organic anion transporting polypeptide 2 (oatp2) have been cloned. At least three forms of mouse oatp2 cDNAs containing the same coding sequence were isolated. The common coding sequence is for a protein of 670 amino acids with 12 putative transmembrane domains. The deduced amino acid sequence of the mouse oatp2 shares 89% identity with the reported rat oatp2. Cloning and analysis of mouse oatp2 gene indicates that these isoforms are alternatively spliced products from the same gene. Heterogeneity was observed in the 5'-untranslated region of the cDNAs. Two of the three isoforms lacked the noncoding exon 3 sequence. Northern-blot hybridization analysis using the exon 3-specific probes demonstrated that mouse oatp2 mRNA containing exon 3 sequence is expressed in heart and lung, whereas exon 1-, 2-, and 17-specific probes detected mRNA only in brain and liver. The mouse oatp2 gene consists of 17 exons, including three noncoding exons, and 16 introns. All of the introns are flanked by GT-AG splice sequences except for intron 10 that is flanked by GC-AG splice sequence.
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MESH Headings
- Alternative Splicing
- Amino Acid Sequence
- Animals
- Anion Transport Proteins
- Base Sequence
- Blotting, Northern
- Carrier Proteins/genetics
- Cloning, Molecular
- DNA/chemistry
- DNA/genetics
- DNA, Complementary/chemistry
- DNA, Complementary/genetics
- Exons
- Gene Expression Regulation
- Genes/genetics
- Introns
- Mice
- Mice, Inbred BALB C
- Mice, Inbred Strains
- Molecular Sequence Data
- Phylogeny
- Promoter Regions, Genetic
- RNA, Messenger/genetics
- RNA, Messenger/metabolism
- Sequence Alignment
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- Tissue Distribution
- Transcription, Genetic
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Affiliation(s)
- K Ogura
- Department of Pharmacology, Toxicology and Therapeutics, University of Kansas Medical Center, Kansas City, Kansas 66160-7417, USA
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18
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Haller K, Ruckes T, Schmitt I, Saul D, Derow E, Grassmann R. Tax-dependent stimulation of G1 phase-specific cyclin-dependent kinases and increased expression of signal transduction genes characterize HTLV type 1-transformed T cells. AIDS Res Hum Retroviruses 2000; 16:1683-8. [PMID: 11080810 DOI: 10.1089/08892220050193146] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Human T cell leukemia virus protein induces T cells to permanent IL-2-dependent growth. These cells occasionally convert to factor independence. The viral oncoprotein Tax acts as an essential growth factor of transformed lymphocytes and stimulates the cell cycle in the G(1) phase. In T cells and fibroblasts Tax enhances the activity of the cyclin-dependent kinases (CDK) CDK4 and CDK6. These kinases, which require binding to cyclin D isotypes for their activity, control the G(1) phase. Coimmunoprecipitation from these cells revealed that Tax associates with cyclin D3/CDK6, suggesting a direct activation of this kinase. The CDK stimulation may account in part for the mitogenic Tax effect, which causes IL-2-dependent T cell growth by Tax. To address the conversion to IL-2-independent proliferation and to identify overexpressed genes, which contribute to the transformed growth, the gene expression patterns of HTLV-1-transformed T cells were compared with that of peripheral blood lymphocytes. Potentially overexpressed cDNAs were cloned, sequenced, and used to determine the RNA expression. Genes found to be up-regulated are involved in signal transduction (STAT5a, cyclin G(1), c-fgr, hPGT) and also glycoprotein synthesis (LDLC, ribophorin). Many of these are also activated during T cell activation and implicated in the regulation of growth and apoptosis. The transcription factor STAT5a, which is involved in IL-2 signaling, was strongly up-regulated only in IL-2-independent cells, thus suggesting that it contributes to factor-independent growth. Thus, the differentially expressed genes could cooperate with the Tax-induced cell cycle stimulation in the maintenance of IL-2-dependent and IL-2-independent growth of HTLV-transformed lymphocytes.
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Affiliation(s)
- K Haller
- Institut für Klinische und Molekulare Virologie, D-91054 Erlangen, Germany
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19
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Li L, Meier PJ, Ballatori N. Oatp2 mediates bidirectional organic solute transport: a role for intracellular glutathione. Mol Pharmacol 2000; 58:335-40. [PMID: 10908301 DOI: 10.1124/mol.58.2.335] [Citation(s) in RCA: 175] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
One member of the OATP family of transporters, rat Oatp1, functions as an anion exchanger that is driven in part by the glutathione (GSH) electrochemical gradient, indicating that other OATP-related transporters may also be energized by this mechanism. The present study examined whether rat Oatp2 is also an anion exchanger, and, if so, whether it is energized by the GSH electrochemical gradient. As with Oatp1, uptake of 10 microM [(3)H]taurocholate in Oatp2-expressing Xenopus laevis oocytes was trans-stimulated by intracellular 0.2 mM unlabeled taurocholate, indicating bidirectional transport. Interestingly, [(3)H]taurocholate uptake in Oatp2-expressing oocytes was also trans-stimulated when oocytes were preloaded with GSH, S-methylglutathione, S-sulfobromophthalein-glutathione, S-dinitrophenyl glutathione, or ophthalmic acid (a GSH analog) but not by glutarate or N-acetylcysteine, suggesting that GSH derivatives and conjugates may function as intracellular substrates for Oatp2. Support for this hypothesis was provided by the demonstration of enhanced [(3)H]GSH and [(3)H]S-(2,4-dinitrophenyl)-glutathione efflux in Oatp2-expressing oocytes. However, in contrast to Oatp1, extracellular GSH failed to cis-inhibit uptake of [(3)H]taurocholate or [(3)H]digoxin in Oatp2-expressing oocytes, indicating that the stimulatory effect of high intracellular GSH concentrations is not due to a coupled exchange mechanism. Taken together, the results indicate that Oatp2 mediates bidirectional transport of organic anions by a GSH-sensitive facilitative diffusion mechanism and suggest that this transporter may play a role in cellular export of specific organic molecules.
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Affiliation(s)
- L Li
- Department of Environmental Medicine, University of Rochester School of Medicine, Rochester, New York 14642, USA
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20
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Bennett CN, Horrobin DF. Gene targets related to phospholipid and fatty acid metabolism in schizophrenia and other psychiatric disorders: an update. Prostaglandins Leukot Essent Fatty Acids 2000; 63:47-59. [PMID: 10970713 DOI: 10.1054/plef.2000.0191] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Phospholipids make up about 60% of the brain's dry weight and play key roles in many brain signal tranduction mechanisms. A recent review(1)identified the increasing evidence that abnormal phospholipid and related fatty acid metabolism may contribute to illnesses such as schizophrenia, bipolar disorder, depression and attention deficit hyperactivity disorder. This current paper reviews the main pathways of phospholipid metabolism, emphasizing the role of phospholipases of the A2 in signal tranduction processes. It also updates the chromosomal locations of regions likely to be involved in these disorders, and relates these to the known locations of genes directly or indirectly involved in phospholipid and fatty acid metabolism.
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21
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Tamai I, Nezu J, Uchino H, Sai Y, Oku A, Shimane M, Tsuji A. Molecular identification and characterization of novel members of the human organic anion transporter (OATP) family. Biochem Biophys Res Commun 2000; 273:251-60. [PMID: 10873595 DOI: 10.1006/bbrc.2000.2922] [Citation(s) in RCA: 496] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We identified three novel transporters structurally belonging to the organic anion transporting polypeptide (OATP) family in humans. Since previously known rat oatp1 to 3 do not necessarily correspond to the human OATPs in terms of either tissue distribution or function, here we designate the newly identified human OATPs as OATP-B, -D and -E, and we rename the previously known human OATP as OATP-A. OATP-C proved to be identical with the recently reported LST1/OATP-2. Expression profiles of the five OATPs and the prostaglandin transporter PGT (a member of OATP family) in human tissues showed that OATP-C is exclusively localized in liver, OATP-A and PGT are expressed in restricted ranges of tissues, and OATP-B, -D and -E show broad expression profiles. OATP-B, -C, -D and -E exhibited transport activity for [(3)H]estrone-3-sulfate as a common substrate. OATP-C has a high transport activity with broad substrate specificity.
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Affiliation(s)
- I Tamai
- Faculty of Pharmaceutical Sciences, Kanazawa University, Kanazawa, 920-0934, Japan
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22
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Ogura K, Choudhuri S, Klaassen CD. Full-length cDNA cloning and genomic organization of the mouse liver-specific organic anion transporter-1 (lst-1). Biochem Biophys Res Commun 2000; 272:563-70. [PMID: 10833452 DOI: 10.1006/bbrc.2000.2830] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We have cloned a cDNA that codes for mouse liver-specific transporter-1, mouse lst-1. The cDNA is comprised of 3296 base pairs and it contains a coding sequence for a protein of 689 amino acids with 12 putative transmembrane domains. The deduced amino acid sequence of the mouse lst-1 shares 64 and 77% identities with the reported human and rat lsts, respectively. Northern blot analysis demonstrates that mouse lst-1 mRNA is expressed exclusively in liver. We also report here the structural organization of the mouse lst-1 gene as the first evidence for the structure of a gene encoding an lst. The mouse lst-1 gene spans approximately 60 kbp in length and consists of 16 exons, including two noncoding exons. All the introns are flanked by GT-AG consensus splice sequences. 5'-Rapid Amplification of cDNA Ends (RACE) analyses demonstrate three splice variant mRNAs involving the noncoding exon 2 and exon 3. The 5'-flanking region of the gene contains consensus CAAT and TATA boxes and several potential binding sites for transcription factors for CAAT enhancer binding protein (C/EBP) and hepatocyte nuclear factors (HNF-3beta, HFH-1, and HFH-2), transcription factors important for liver-specific gene expression.
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Affiliation(s)
- K Ogura
- Department of Pharmacology, Toxicology, and Therapeutics, University of Kansas Medical Center, Kansas City 66160-7417, USA
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23
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König J, Cui Y, Nies AT, Keppler D. A novel human organic anion transporting polypeptide localized to the basolateral hepatocyte membrane. Am J Physiol Gastrointest Liver Physiol 2000; 278:G156-64. [PMID: 10644574 DOI: 10.1152/ajpgi.2000.278.1.g156] [Citation(s) in RCA: 382] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We cloned and expressed a new organic anion transporting polypeptide (OATP), termed human OATP2, (OATP-C, LST-1; symbol SLC21A6), involved in the uptake of various lipophilic anions into human liver. The cDNA encoding OATP2 comprised 2073 base pairs, corresponding to a protein of 691 amino acids, which were 44% identical to the known human OATP. An antibody directed against the carboxy terminus localized OATP2 to the basolateral membrane of human hepatocytes. Northern blot analysis indicated a strong expression of OATP2 only in human liver. Transport mediated by recombinant OATP2 and its localization were studied in stably transfected Madin-Darby canine kidney strain II (MDCKII) and HEK293 cells. Confocal microscopy localized recombinant OATP2 protein to the lateral membrane of MDCKII cells. Substrates included 17beta-glucuronosyl estradiol, monoglucuronosyl bilirubin, dehydroepiandrosterone sulfate, and cholyltaurine. 17beta-Glucuronosyl estradiol was a preferred substrate, with a Michaelis-Menten constant value of 8.2 microM; its uptake was Na(+) independent and was inhibited by sulfobromophthalein, with a inhibition constant value of 44 nM. Our results indicate that OATP2 is important for the uptake of organic anions, including bilirubin conjugates and sulfobromophthalein, in human liver.
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Affiliation(s)
- J König
- Division of Tumor Biochemistry, Deutsches Krebsforschungszentrum, D-69120 Heidelberg, Germany.
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24
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Pucci ML, Bao Y, Chan B, Itoh S, Lu R, Copeland NG, Gilbert DJ, Jenkins NA, Schuster VL. Cloning of mouse prostaglandin transporter PGT cDNA: species-specific substrate affinities. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 277:R734-41. [PMID: 10484490 DOI: 10.1152/ajpregu.1999.277.3.r734] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We recently identified and/or cloned the PG transporter PGT in the rat (rPGT) (Kanai, N., R. Lu, J. A. Satriano, Y. Bao, A. W. Wolkoff, and V. L. Schuster, Science 268: 866-869, 1995) and the human (hPGT) (Lu, R., and V. L. Schuster, J. Clin. Invest. 98: 1142-1149, 1996). Here we have cloned and expressed the mouse PGT (mPGT) cDNA. The tissue distribution of mPGT mRNA expression is significantly more restricted than that of rPGT and hPGT mRNA. Although the deduced amino acid sequence of mPGT is similar to the rat (91% identity) and human (82% identity) homologues, it has three regions of dissimilarity: amino acids 128-163 and 283-298, and valine 610 and isoleucine 611 (predicted to lie within putative transmembrane span 12). Affinities of hPGT, rPGT, and mPGT for several PG substrates differed, with hPGT having the highest [low Michaelis constant (K(m))] and mPGT the lowest affinity. A chimeric protein, linking the N-terminal domain of mPGT with the C-terminal domain of hPGT, had affinity for PGE2 indistinguishable from that of hPGT, indicating that the C-terminal domain dictates K(m). We mutagenized mouse valine 610 and isoleucine 611 to their corresponding human residues (methionine and glycine, respectively); however, these changes did not convert the inhibition constant of mPGT to that of hPGT. The mouse gene was localized to chromosome 9 in a region syntenic with the region of human chromosome 3 containing the hPGT gene. These studies highlight the species-dependence of tissue expression and function of PGT and lay the groundwork for the use of the mouse as a model system for the study of PGT function.
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Affiliation(s)
- M L Pucci
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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25
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Horrobin DF, Bennett CN. New gene targets related to schizophrenia and other psychiatric disorders: enzymes, binding proteins and transport proteins involved in phospholipid and fatty acid metabolism. Prostaglandins Leukot Essent Fatty Acids 1999; 60:141-67. [PMID: 10359017 DOI: 10.1054/plef.1999.0027] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Phospholipids make up about 60% of the brain's dry weight. In spite of this, phospholipid metabolism has received relatively little attention from those seeking genetic factors involved in psychiatric and neurological disorders. However, there is now increasing evidence from many quarters that abnormal phospholipid and related fatty acid metabolism may contribute to illnesses such as schizophrenia, bipolar disorder, depression and attention deficit hyperactivity disorder. To date the possible specific proteins and genes involved have been relatively ill-defined. This paper reviews the main pathways of phospholipid metabolism, emphasizing the roles of phospholipases of the A2 and C series in signal transduction processes. It identifies some likely protein candidates for involvement in psychiatric and neurological disorders. It also reviews the chromosomal locations of regions likely to be involved in these disorders, and relates these to the known locations of genes directly or indirectly involved in phospholipid and fatty acid metabolism.
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Affiliation(s)
- D F Horrobin
- Laxdale Research, Kings Park House, Laurelhill Business Park, Stirling, UK
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