TNP [N2-(m-Trifluorobenzyl), N6-(p-nitrobenzyl)purine] ameliorates diet induced obesity and insulin resistance via inhibition of the IP6K1 pathway.
OBJECTIVE
Obesity and type 2 diabetes (T2D) lead to various life-threatening diseases such as coronary heart disease, stroke, osteoarthritis, asthma, and neurodegeneration. Therefore, extensive research is ongoing to identify novel pathways that can be targeted in obesity/T2D. Deletion of the inositol pyrophosphate (5-IP7) biosynthetic enzyme, inositol hexakisphosphate kinase-1 (IP6K1), protects mice from high fat diet (HFD) induced obesity (DIO) and insulin resistance. Yet, whether this pathway is a valid pharmacologic target in obesity/T2D is not known. Here, we demonstrate that TNP [N2-(m-Trifluorobenzyl), N6-(p-nitrobenzyl)purine], a pan-IP6K inhibitor, has strong anti-obesity and anti-diabetic effects in DIO mice.


METHODS
Q-NMR, GTT, ITT, food intake, energy expenditure, QRT-PCR, ELISA, histology, and immunoblot studies were conducted in short (2.5-week)- and long (10-week)-term TNP treated DIO C57/BL6 WT and IP6K1-KO mice, under various diet and temperature conditions.


RESULTS
TNP, when injected at the onset of HFD-feeding, decelerates initiation of DIO and insulin resistance. Moreover, TNP facilitates weight loss and restores metabolic parameters, when given to DIO mice. However, TNP does not reduce weight gain in HFD-fed IP6K1-KO mice. TNP specifically enhances insulin sensitivity in DIO mice via Akt activation. TNP decelerates weight gain primarily by enhancing thermogenic energy expenditure in the adipose tissue. Accordingly, TNP's effect on body weight is partly abolished whereas its impact on glucose homeostasis is preserved at thermoneutral temperature.


CONCLUSIONS
Pharmacologic inhibition of the inositol pyrophosphate pathway has strong therapeutic potential in obesity, T2D, and other metabolic diseases.
Department of Metabolism and Aging, The Scripps Research Institute, Jupiter, FL 33458, USA.
Sarbani
S
Ghoshal
Department of Metabolism and Aging, The Scripps Research Institute, Jupiter, FL 33458, USA.
Qingzhang
Q
Zhu
Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, FL 33458, USA.
Alice
A
Asteian
Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, FL 33458, USA.
Hua
H
Lin
Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA.
Haifei
H
Xu
Drug Discovery Division, Lieber Institute for Brain Development, Baltimore, MD 21205, USA.
Glen
G
Ernst
Drug Discovery Division, Lieber Institute for Brain Development, Baltimore, MD 21205, USA.
James C
JC
Barrow
Department of Neuroscience, The Scripps Research Institute, Jupiter, FL 33458, USA.
Baoji
B
Xu
Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, FL 33458, USA.
Michael D
MD
Cameron
Department of Molecular Therapeutics, The Scripps Research Institute, Jupiter, FL 33458, USA.
Theodore M
TM
Kamenecka
Department of Metabolism and Aging, The Scripps Research Institute, Jupiter, FL 33458, USA. Electronic address: achakrab@scripps.edu.
Anutosh
A
Chakraborty
5-IP7, diphosphoinositol pentakisphosphate; ALT, alanine aminotransferase; AST, aspartate transaminase; AUC, area under curve; Akt; BAT, brown adipose tissue; CD, chow-diet; CPT1a, carnitine palmitoyltransferase I; Cidea, cell death activator-A; DIO, diet-induced obesity; Diabetes; EE, energy expenditure; EWAT, epididymal adipose tissue; Energy expenditure; GSK3, glycogen synthase kinase; GTT, glucose tolerance test; H&E, hematoxylin and eosin; HFD, high-fat diet; HPLC, high performance liquid chromatography; IP6K; IP6K, Inositol hexakisphosphate kinase; IP6K1-KO, IP6K1 knockout; ITT, insulin tolerance test; IWAT, inguinal adipose tissue; Inositol pyrophosphate; Obesity; PCR, polymerase chain reaction; PGC1α, PPAR coactivator 1 alpha; PKA, protein kinase A; PPARγ, peroxisome proliferator-activated receptor gamma; PRDM16, PR domain containing 16; Pro-TNP, TNP treatment for protection against DIO; Q-NMR, quantitative nuclear magnetic resonance; QRT-PCR, quantitative reverse transcription polymerase chain reaction; RER, Respiratory exchange ratio; RWAT, retroperitoneal adipose tissue; Rev-TNP, long-term TNP treatment for reversal of DIO; RevT-TNP, Long-term TNP treatment for reversal of DIO at thermoneutral temperature; S473, serine 473; S9, serine 9; SREV-TNP, short-term TNP treatment for reversal of DIO; T2D, type-2 diabetes; T308, threonine 308; TNP, [N2-(m-Trifluorobenzyl), N6-(p-nitrobenzyl)purine]; UCP-1/3, uncoupling protein 1/3; VO2, volume of oxygen consumption; WAT, white adipose tissue
J Mol Signal. 2010 May 26;5:5
20504366
Biochem Biophys Res Commun. 2014 Jul 18;450(1):255-60
24944017
Curr Opin Lipidol. 2009 Apr;20(2):98-105
19276888
Curr Opin Endocrinol Diabetes Obes. 2010 Apr;17(2):143-9
20160646
J Neurosci. 2015 Aug 5;35(31):11056-67
26245967
Proc Natl Acad Sci U S A. 2008 Feb 19;105(7):2349-53
18268345
PLoS One. 2012;7(2):e32386
22384237
Nat Methods. 2011 Dec 28;9(1):57-63
22205519
Nat Rev Drug Discov. 2010 Dec;9(12 ):929-39
21119731
Biochem Soc Trans. 1997 Aug;25(3):981-8
9388586
Biochem J. 2014 Aug 15;462(1):173-84
24865181
Physiol Behav. 2004 Apr;81(2):243-8
15159170
Proc Natl Acad Sci U S A. 2015 Feb 10;112(6):1773-8
25617365
J Hum Genet. 2004;49(7):360-5
15221640
J Clin Invest. 2000 Aug;106(4):473-81
10953022
Nat Rev Endocrinol. 2014 Mar;10(3):157-63
24296515
J Biol Chem. 2003 Mar 21;278(12 ):10221-31
12525499
Obes Rev. 2014 Feb;15(2):92-106
24165204
JAMA. 2014 Jan 1;311(1):74-86
24231879
Stem Cell Res Ther. 2014 Mar 26;5(2):33
24670364
N Engl J Med. 2009 Apr 9;360(15):1509-17
19357406
Blood. 2013 Aug 22;122(8):1478-86
23782934
Cell Metab. 2008 Feb;7(2):159-72
18249175
Science. 2001 Jun 1;292(5522):1728-31
11387480
J Biol Chem. 2001 Oct 19;276(42):39179-85
11502751
Trends Mol Med. 2015 Sep;21(9):571-9
26271143
Science. 2005 Feb 18;307(5712):1098-101
15718470
Nat Immunol. 2011 Jun 19;12(8):752-60
21685907
Mol Cell. 2014 Apr 10;54(1):119-32
24657168
Science. 2002 Aug 2;297(5582):843-5
12161655
Proc Natl Acad Sci U S A. 2008 Jan 29;105(4):1134-9
18195352
Dis Model Mech. 2012 Sep;5(5):621-6
22915024
Chem Sci. 2013 Jan;4(1):405-410
23378892
ACS Chem Biol. 2013 Jan 18;8(1):96-104
23276252
Mol Pharmacol. 2006 Sep;70(3):779-85
16760360
Science. 2007 Nov 23;318(5854):1299-302
18033884
Diabetes. 2005 Jun;54(6):1692-7
15919790
Cell Mol Life Sci. 2009 Dec;66(24):3851-71
19714294
J Microsc. 1989 Jul;155(Pt 1):113-21
2769747
Science. 2011 Nov 11;334(6057):802-5
22076377
Biochem Soc Trans. 2016 Feb;44(1):191-6
26862205
Int J Obes (Lond). 2008 Dec;32 Suppl 7:S32-8
19136989
Nature. 2010 Jul 22;466(7305):451-6
20651683
Cell. 2003 Sep 5;114(5):559-72
13678580
Cell. 2014 Jan 16;156(1-2):20-44
24439368
Biochem J. 2013 Jun 15;452(3):369-79
23725456
Cell Metab. 2015 Jan 6;21(1):33-8
25565203
Proc Natl Acad Sci U S A. 2013 May 7;110(19):7726-31
23610437
Curr Med Chem. 2004 Jun;11(12):1595-615
15180566
Curr Opin Endocrinol Diabetes Obes. 2012 Apr;19(2):81-7
22327367
J Neurosci. 2013 Feb 20;33(8):3363-9
23426664
Cell Metab. 2015 Dec 1;22(6):997-1008
26525534
Curr Biol. 1999 Nov 18;9(22):1323-6
10574768
Nature. 2012 Jan 11;481(7382):463-8
22237023
Chembiochem. 2002 Sep 2;3(9):897-901
12210991
Obesity (Silver Spring). 2007 Apr;15(4):798-808
17426312
Diabetes. 1998 Aug;47(8):1281-6
9703329
Trends Pharmacol Sci. 2013 Jun;34(6):347-55
23648356
Cell Metab. 2015 Aug 4;22(2):279-90
26166748
Obesity (Silver Spring). 2013 Feb;21(2):218-28
23404923
Cell. 2007 Jun 29;129(7):1261-74
17604717
Clin Pharmacol Ther. 2014 Jan;95(1):53-66
24105257
Obes Res. 1997 Nov;5(6):650-6
9449154
Sci Signal. 2011 Aug 23;4(188):re1
21878680
J Biol Chem. 2009 Apr 17;284(16):10571-82
19208622
J Cell Mol Med. 2015 Jun;19(6):1296-307
25752217
Exp Biol Med (Maywood). 2005 Oct;230(9):593-605
16179727
Nat Commun. 2016 Feb 04;7:10622
26842801
EMBO Rep. 2015 Oct;16(10 ):1378-93
26303948
Am J Med Sci. 2013 Apr;345(4):284-8
23531960
Nat Med. 2014 Aug;20(8):911-8
25038826
Nat Chem Biol. 2011 Nov 27;8(1):111-6
22119861
Neth J Med. 2007 May;65(5):157-9
17519510
Pharm Res. 2011 Aug;28(8):1792-818
21181547
Pharmacol Rev. 2012 Jan;64(1):16-64
22039149
J Clin Invest. 2013 Aug;123(8):3404-8
23867622
Mol Psychiatry. 2014 Mar;19(3):284-93
23439485
Trends Endocrinol Metab. 2014 Jun;25(6):303-11
24709036
J Biosci. 2015 Sep;40(3):593-605
26333405
Nat Rev Drug Discov. 2010 Jun;9(6):465-82
20514071
Curr Biol. 1997 Apr 1;7(4):261-9
9094314
Biochem J. 2016 Oct 1;473(19):3031-47
27474409
Nat Med. 2013 Oct;19(10 ):1252-63
24100998
Acta Pharmacol Sin. 2012 Feb;33(2):173-81
22301857
Neuron. 2001 Aug 16;31(3):439-51
11516400
PLoS One. 2009;4(5):e5580
19440344
Cell. 2010 Dec 10;143(6):897-910
21145457
Circ Res. 1997 Aug;81(2):274-81
9242189
Diabetes Metab Syndr Obes. 2014 Feb 13;7:55-64
24611020
Proc Natl Acad Sci U S A. 2010 Nov 16;107(46):19921-6
20980661
Diabetes Metab Res Rev. 2012 Dec;28 Suppl 2:8-20
23280861
Nat Cell Biol. 2011 Apr;13(4):434-46
21441927
Int J Biochem Cell Biol. 2016 Sep;78:149-55
27373682
J Pharm Sci Pharmacol. 2014 Jun 1;1(2):160-164
26213696