title: State-Dependent Allosteric Inhibition of the Human SLC13A5 Citrate Transporter by Hydroxysuccinic Acids, PF-06649298 and PF-06761281.
abstract: In the liver, citrate is a key metabolic intermediate involved in the regulation of glycolysis and lipid synthesis and reduced expression of the hepatic citrate SLC13A5 transporter has been shown to improve metabolic outcomes in various animal models. Although inhibition of hepatic extracellular citrate uptake through SLC13A5 has been suggested as a potential therapeutic approach for Type-2 diabetes and/or fatty liver disease, so far, only a few SLC13A5 inhibitors have been identified. Moreover, their mechanism of action still remains unclear, potentially limiting their utility for in vivo proof-of-concept studies. In this study, we characterized the pharmacology of the recently identified hydroxysuccinic acid SLC13A5 inhibitors, PF-06649298 and PF-06761281, using a combination of14C-citrate uptake, a membrane potential assay and electrophysiology. In contrast to their previously proposed mechanism of action, our data suggest that both PF-06649298 and PF-06761281 are allosteric, state-dependent SLC13A5 inhibitors, with low-affinity substrate activity in the absence of citrate. As allosteric state-dependent modulators, the inhibitory potency of both compounds is highly dependent on the ambient citrate concentration and our detailed mechanism of action studies therefore, may be of value in interpreting the in vivo effects of these compounds.
authors.affiliation: Molecular and Cellular Pharmacology, Discovery Sciences, Janssen R&D, LLC., San Diego, California (M.-L.R., M.S., A.D.W.) and Cardiovascular and Metabolism Discovery, Janssen R&D, LLC., Springhouse, Pennsylvania, (B.Z., S.A.H.).
authors.forename: Marie-Laure
authors.initials: ML
authors.lastname: Rives
authors.affiliation: Molecular and Cellular Pharmacology, Discovery Sciences, Janssen R&D, LLC., San Diego, California (M.-L.R., M.S., A.D.W.) and Cardiovascular and Metabolism Discovery, Janssen R&D, LLC., Springhouse, Pennsylvania, (B.Z., S.A.H.).
authors.forename: Morena
authors.initials: M
authors.lastname: Shaw
authors.affiliation: Molecular and Cellular Pharmacology, Discovery Sciences, Janssen R&D, LLC., San Diego, California (M.-L.R., M.S., A.D.W.) and Cardiovascular and Metabolism Discovery, Janssen R&D, LLC., Springhouse, Pennsylvania, (B.Z., S.A.H.).
authors.forename: Bin
authors.initials: B
authors.lastname: Zhu
authors.affiliation: Molecular and Cellular Pharmacology, Discovery Sciences, Janssen R&D, LLC., San Diego, California (M.-L.R., M.S., A.D.W.) and Cardiovascular and Metabolism Discovery, Janssen R&D, LLC., Springhouse, Pennsylvania, (B.Z., S.A.H.).
authors.forename: Simon A
authors.initials: SA
authors.lastname: Hinke
authors.affiliation: Molecular and Cellular Pharmacology, Discovery Sciences, Janssen R&D, LLC., San Diego, California (M.-L.R., M.S., A.D.W.) and Cardiovascular and Metabolism Discovery, Janssen R&D, LLC., Springhouse, Pennsylvania, (B.Z., S.A.H.) awickend@its.jnj.com.
authors.forename: Alan D
authors.initials: AD
authors.lastname: Wickenden
mesh_terms: D000494:Allosteric Regulation / Q000187:drug effects; D002250:Carbon Radioisotopes; D019343:Citric Acid / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D008293:Malates / Q000737:chemistry / Q000494:pharmacology*; D008954:Models, Biological; D018408:Patch-Clamp Techniques; D010654:Phenylbutyrates / Q000737:chemistry / Q000494:pharmacology*; D011725:Pyridines / Q000737:chemistry / Q000494:pharmacology*; D013379:Substrate Specificity / Q000187:drug effects; D013386:Succinates / Q000737:chemistry / Q000494:pharmacology*; D027981:Symporters / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D002250:Carbon Radioisotopes; D008293:Malates; C000618269:PF-06649298; C000609014:PF-06761281; D010654:Phenylbutyrates; D011725:Pyridines; C470492:SLC13A5 protein, human; D013386:Succinates; D027981:Symporters; D019343:Citric Acid