Hinkovska-Galcheva V

References (4)

Title : Inhibition of lysosomal phospholipase A2 predicts drug-induced phospholipidosis - Hinkovska-Galcheva_2021_J.Lipid.Res_62_100089
Author(s) : Hinkovska-Galcheva V , Treadwell T , Shillingford JM , Lee A , Abe A , Tesmer JJG , Shayman JA
Ref : J Lipid Res , 62 :100089 , 2021
Abstract : Phospholipidosis, the excessive accumulation of phospholipids within lysosomes, is a pathological response observed following exposure to many drugs across multiple therapeutic groups. A clear mechanistic understanding of the causes and implications of this form of drug toxicity has remained elusive. We previously reported the discovery and characterization of a lysosome-specific phospholipase A2 (PLA2G15) and later reported that amiodarone, a known cause of drug-induced phospholipidosis, inhibits this enzyme. Here, we assayed a library of 163 drugs for inhibition of PLA2G15 to determine whether this phospholipase was the cellular target for therapeutics other than amiodarone that cause phospholipidosis. We observed that 144 compounds inhibited PLA2G15 activity. Thirty-six compounds not previously reported to cause phospholipidosis inhibited PLA2G15 with IC(50) values less than 1 mM and were confirmed to cause phospholipidosis in an in vitro assay. Within this group, fosinopril was the most potent inhibitor (IC(50) 0.18 microM). Additional characterization of the inhibition of PLA2G15 by fosinopril was consistent with interference of PLA2G15 binding to liposomes. PLA2G15 inhibition was more accurate in predicting phospholipidosis compared with in silico models based on pKa and ClogP, measures of protonation, and transport-independent distribution in the lysosome, respectively. In summary, PLA2G15 is a primary target for cationic amphiphilic drugs that cause phospholipidosis, and PLA2G15 inhibition by cationic amphiphilic compounds provides a potentially robust screening platform for potential toxicity during drug development.
ESTHER : Hinkovska-Galcheva_2021_J.Lipid.Res_62_100089
PubMedSearch : Hinkovska-Galcheva_2021_J.Lipid.Res_62_100089
PubMedID: 34087196

Title : Structural Basis of Lysosomal Phospholipase A2 Inhibition by Zn(2) - Bouley_2019_Biochemistry_58_1709
Author(s) : Bouley RA , Hinkovska-Galcheva V , Shayman JA , Tesmer JJG
Ref : Biochemistry , 58 :1709 , 2019
Abstract : Lysosomal phospholipase A2 (LPLA2/PLA2G15) is a key enzyme involved in lipid homeostasis and is characterized by both phospholipase A2 and transacylase activity and by an acidic pH optimum. Divalent cations such as Ca(2+) and Mg(2+) have previously been shown to have little effect on the activity of LPLA2, but the discovery of a novel crystal form of LPLA2 with Zn(2+) bound in the active site suggested a role for this divalent cation in regulating enzyme activity. In this complex, the cation directly coordinates the serine and histidine of the alpha/beta-hydrolase triad and stabilizes a closed conformation. This closed conformation is characterized by an inward shift of the lid loop, which extends over the active site and effectively blocks access to one of its lipid acyl chain binding tracks. Therefore, we hypothesized that Zn(2+) would inhibit LPLA2 activity at a neutral but not acidic pH because histidine would be positively charged at lower pH. Indeed, Zn(2+) was found to inhibit the esterase activity of LPLA2 in a noncompetitive manner exclusively at a neutral pH (between 6.5 and 8.0). Because lysosomes are reservoirs of Zn(2+) in cells, the pH optimum of LPLA2 might allow it to catalyze acyl transfer unimpeded within the organelle. We conjecture that Zn(2+) inhibition of LPLA2 at higher pH maintains a lower activity of the esterase in environments where its activity is not typically required.
ESTHER : Bouley_2019_Biochemistry_58_1709
PubMedSearch : Bouley_2019_Biochemistry_58_1709
PubMedID: 30830753
Gene_locus related to this paper: human-PLA2G15

Title : Determinants of pH profile and acyl chain selectivity in lysosomal phospholipase A2 - Hinkovska-Galcheva_2018_J.Lipid.Res_59_1205
Author(s) : Hinkovska-Galcheva V , Kelly R , Manthei KA , Bouley R , Yuan W , Schwendeman A , Tesmer JJG , Shayman JA
Ref : J Lipid Res , 59 :1205 , 2018
Abstract : Lysosomal phospholipase A2 (LPLA2) is characterized by broad substrate recognition, peak activity at acidic pH, and the transacylation of lipophilic alcohols, especially N-acetyl-sphingosine. Prior structural analysis of LPLA2 revealed the presence of an atypical acidic residue, Asp13, in the otherwise hydrophobic active site cleft. We hypothesized that Asp13 contributed to the pH profile and/or substrate preference of LPLA2 for unsaturated acyl chains. To test this hypothesis, we substituted Asp13 for alanine, cysteine, or phenylalanine; then, we monitored the formation of 1-O-acyl-N-acetylsphingosine to measure the hydrolysis of sn-1 versus sn-2 acyl groups on a variety of glycerophospholipids. Substitutions with Asp13 yielded significant enzyme activity at neutral pH (7.4) and perturbed the selectivity for mono- and double-unsaturated acyl chains. However, this position played no apparent role in selecting for either the acyl acceptor or the head group of the glycerophospholipid. Our modeling indicates that Asp13 and its substitutions contribute to the pH activity profile of LPLA2 and to acyl chain selectivity by forming part of a hydrophobic track occupied by the scissile acyl chain.
ESTHER : Hinkovska-Galcheva_2018_J.Lipid.Res_59_1205
PubMedSearch : Hinkovska-Galcheva_2018_J.Lipid.Res_59_1205
PubMedID: 29724779

Title : Structure and function of lysosomal phospholipase A2 and lecithin:cholesterol acyltransferase - Glukhova_2015_Nat.Commun_6_6250
Author(s) : Glukhova A , Hinkovska-Galcheva V , Kelly R , Abe A , Shayman JA , Tesmer JJ
Ref : Nat Commun , 6 :6250 , 2015
Abstract : Lysosomal phospholipase A2 (LPLA2) and lecithin:cholesterol acyltransferase (LCAT) belong to a structurally uncharacterized family of key lipid-metabolizing enzymes responsible for lung surfactant catabolism and for reverse cholesterol transport, respectively. Whereas LPLA2 is predicted to underlie the development of drug-induced phospholipidosis, somatic mutations in LCAT cause fish eye disease and familial LCAT deficiency. Here we describe several high-resolution crystal structures of human LPLA2 and a low-resolution structure of LCAT that confirms its close structural relationship to LPLA2. Insertions in the alpha/beta hydrolase core of LPLA2 form domains that are responsible for membrane interaction and binding the acyl chains and head groups of phospholipid substrates. The LCAT structure suggests the molecular basis underlying human disease for most of the known LCAT missense mutations, and paves the way for rational development of new therapeutics to treat LCAT deficiency, atherosclerosis and acute coronary syndrome.
ESTHER : Glukhova_2015_Nat.Commun_6_6250
PubMedSearch : Glukhova_2015_Nat.Commun_6_6250
PubMedID: 25727495
Gene_locus related to this paper: human-LCAT