title: Characterization of FKGK18 as inhibitor of group VIA Ca2+-independent phospholipase A2 (iPLA2β): candidate drug for preventing beta-cell apoptosis and diabetes.
abstract: Ongoing studies suggest an important role for iPLA2β in a multitude of biological processes and it has been implicated in neurodegenerative, skeletal and vascular smooth muscle disorders, bone formation, and cardiac arrhythmias. Thus, identifying an iPLA2βinhibitor that can be reliably and safely used in vivo is warranted. Currently, the mechanism-based inhibitor bromoenol lactone (BEL) is the most widely used to discern the role of iPLA2β in biological processes. While BEL is recognized as a more potent inhibitor of iPLA2 than of cPLA2 or sPLA2, leading to its designation as a "specific" inhibitor of iPLA2, it has been shown to also inhibit non-PLA2 enzymes. A potential complication of its use is that while the S and R enantiomers of BEL exhibit preference for cytosol-associated iPLA2β and membrane-associated iPLA2γ, respectively, the selectivity is only 10-fold for both. In addition, BEL is unstable in solution, promotes irreversible inhibition, and may be cytotoxic, making BEL not amenable for in vivo use. Recently, a fluoroketone (FK)-based compound (FKGK18) was described as a potent inhibitor of iPLA2β. Here we characterized its inhibitory profile in beta-cells and find that FKGK18: (a) inhibits iPLA2β with a greater potency (100-fold) than iPLA2γ, (b) inhibition of iPLA2β is reversible, (c) is an ineffective inhibitor of α-chymotrypsin, and (d) inhibits previously described outcomes of iPLA2β activation including (i) glucose-stimulated insulin secretion, (ii) arachidonic acid hydrolysis; as reflected by PGE2 release from human islets, (iii) ER stress-induced neutral sphingomyelinase 2 expression, and (iv) ER stress-induced beta-cell apoptosis. These findings suggest that FKGK18 is similar to BEL in its ability to inhibit iPLA2β. Because, in contrast to BEL, it is reversible and not a non-specific inhibitor of proteases, it is suggested that FKGK18 is more ideal for ex vivo and in vivo assessments of iPLA2β role in biological functions.
authors: Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America.
authors: Tomader
authors: T
authors: Ali
authors: George
authors: G
authors: Kokotos
authors: Victoria
authors: V
authors: Magrioti
authors: Robert N
authors: RN
authors: Bone
authors: James A
authors: JA
authors: Mobley
authors: William
authors: W
authors: Hancock
authors: Sasanka
authors: S
authors: Ramanadham
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D002918:Chymotrypsin / Q000037:antagonists & inhibitors / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects / Q000201:enzymology; D003920:Diabetes Mellitus / Q000188:drug therapy* / Q000473:pathology / Q000517:prevention & control*; D015232:Dinoprostone / Q000096:biosynthesis; D004353:Drug Evaluation, Preclinical; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology / Q000627:therapeutic use; D005947:Glucose / Q000494:pharmacology; D054522:Group VI Phospholipases A2 / Q000037:antagonists & inhibitors* / Q000378:metabolism; D006801:Humans; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D007659:Ketones / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D051379:Mice; D009206:Myocardium / Q000378:metabolism; D009281:Naphthalenes / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D011753:Pyrones / Q000494:pharmacology; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism; D013997:Time Factors
chemical_list: C587596:1,1,1-trifluoro-6-(naphthalen-2-yl)hexan-2-one; D004791:Enzyme Inhibitors; D007328:Insulin; D007659:Ketones; D009281:Naphthalenes; D011753:Pyrones; C068314:6-(bromomethylene)tetrahydro-3-(1-naphthaleneyl)-2H-pyran-2-one; D054522:Group VI Phospholipases A2; C516476:Pla2g6 protein, mouse; D013108:Sphingomyelin Phosphodiesterase; D002918:Chymotrypsin; D005947:Glucose; D015232:Dinoprostone; D002118:Calcium
references: Biochemistry. 2006 May 23;45(20):6392-406
references: 16700550
references: Brain. 2009 May;132(Pt 5):1221-35
references: 19218359
references: Cell Signal. 2005 Sep;17(9):1052-62
references: 15993747
references: J Biol Chem. 1991 Apr 15;266(11):7227-32
references: 2016324
references: J Biol Chem. 1983 Dec 25;258(24):15046-53
references: 6654902
references: Am J Physiol Endocrinol Metab. 2002 Apr;282(4):E820-33
references: 11882502
references: J Biol Chem. 1994 Mar 25;269(12):9227-33
references: 8132660
references: Chem Rev. 2011 Oct 12;111(10):6130-85
references: 21910409
references: J Biol Chem. 2006 Jul 28;281(30):20958-20973
references: 16732058
references: Biochim Biophys Acta. 1992 May 8;1125(3):280-91
references: 1596516
references: Biochemistry. 2004 Feb 3;43(4):918-30
references: 14744135
references: J Biol Chem. 1999 Apr 2;274(14):9607-16
references: 10092647
references: J Biol Chem. 2004 Sep 10;279(37):38194-200
references: 15252026
references: Biochemistry. 1993 May 25;32(20):5339-51
references: 8499439
references: Diabetes Obes Metab. 2010 Oct;12 Suppl 2:93-8
references: 21029305
references: Diabetes. 1993 Mar;42(3):367-74
references: 8432406
references: J Biol Chem. 2003 Nov 7;278(45):44683-90
references: 12952946
references: Biochim Biophys Acta. 2006 Nov;1761(11):1246-59
references: 16973413
references: J Biol Chem. 1995 Jan 6;270(1):445-50
references: 7814408
references: Biochemistry. 1991 Jul 2;30(26):6372-9
references: 1905151
references: Biochemistry. 1986 Mar 25;25(6):1436-44
references: 3964685
references: J Biol Chem. 2010 Feb 26;285(9):6693-705
references: 20032468
references: J Med Chem. 2010 May 13;53(9):3602-10
references: 20369880
references: Curr Drug Targets. 2008 Aug;9(8):683-97
references: 18691015
references: J Biol Chem. 1982 Jan 25;257(2):610-2
references: 7054169
references: Expert Opin Ther Pat. 2013 Mar;23(3):333-44
references: 23294257
references: J Immunol. 2010 Feb 1;184(3):1507-15
references: 20053941
references: Biochemistry. 2006 Jan 24;45(3):1061-73
references: 16411783
references: Psychopharmacology (Berl). 2005 Sep;181(2):392-400
references: 15830227
references: J Biol Chem. 1996 Dec 13;271(50):31937-41
references: 8943239
references: Biochemistry. 1993 Jan 12;32(1):327-36
references: 8418853
references: J Biol Chem. 2010 Mar 19;285(12):8628-38
references: 20086008
references: J Med Chem. 2006 May 4;49(9):2821-8
references: 16640343
references: J Biol Chem. 2000 Apr 7;275(14):9937-45
references: 10744668
references: Biochimie. 2010 Jun;92(6):627-37
references: 20083151
references: J Pediatr Surg. 2001 Jan;36(1):43-50
references: 11150436
references: Biochem Pharmacol. 2008 Oct 30;76(9):1059-67
references: 18775417
references: Biochemistry. 1990 May 8;29(18):4305-11
references: 2350538
references: Semin Cell Dev Biol. 1997 Jun;8(3):297-303
references: 10024493
references: J Biol Chem. 2004 Nov 19;279(47):48968-75
references: 15364929
references: Biochemistry. 1993 Jan 12;32(1):337-46
references: 8418854
references: J Biol Chem. 1997 Apr 25;272(17):11118-27
references: 9111008
references: J Biol Chem. 1997 Mar 28;272(13):8576-80
references: 9079688
references: Am J Physiol Endocrinol Metab. 2008 Feb;294(2):E217-29
references: 17895289
references: Am J Physiol Heart Circ Physiol. 2011 Jan;300(1):H326-34
references: 21037228
references: J Biol Chem. 1999 May 14;274(20):13915-27
references: 10318801
references: Biochim Biophys Acta. 1998 Apr 22;1391(3):384-400
references: 9555100
references: Biochemistry. 1993 Dec 14;32(49):13499-509
references: 8257685
references: Am J Physiol Endocrinol Metab. 2012 Dec 1;303(11):E1386-95
references: 23074238
references: J Biol Chem. 2002 Sep 6;277(36):32807-14
references: 12089145
references: J Am Chem Soc. 2013 Jan 30;135(4):1330-7
references: 23256506
references: Biochemistry. 2007 Sep 4;46(35):10170-85
references: 17685585
references: Islets. 2013 Jan-Feb;5(1):29-44
references: 23411472
references: J Biol Chem. 2002 Jun 7;277(23):20942-8
references: 11927584
references: J Biol Chem. 2008 Dec 12;283(50):34819-32
references: 18936091