Selected Publications

Academic Article

Year Title Altmetric
2022 Targeting Acid Ceramidase Inhibits Glioblastoma Cell Migration through Decreased AKT SignalingCells.  11. 2022
2022 Deletion of Gdf15 Reduces ER Stress-induced Beta-cell Apoptosis and Diabetes 2022
2022 Ca2+-independent phospholipase A2β-derived PGE2 contributes to osteogenesisProstaglandins and Other Lipid Mediators.  158. 2022
2021 Alterations in β-cell sphingolipid profile associated with er stress and ipla2 β: Another contributor to β-cell apoptosis in type 1 diabetesMolecules.  26. 2021
2021 The impact of the ca2+-independent phospholipase a2 β (Ipla2 β) on immune cellsBiomolecules.  11. 2021
2020 Saturated Hydroxy Fatty Acids Exhibit a Cell Growth Inhibitory Activity and Suppress the Cytokine-Induced β-Cell ApoptosisJournal of Medicinal Chemistry.  63:12666-12681. 2020
2020 Metabolic effects of selective deletion of group via phospholipase a2 from macrophages or pancreatic islet beta-cellsBiomolecules.  10:1-23. 2020
2020 Sphingolipid metabolism in glioblastoma and metastatic brain tumors: A review of sphingomyelinases and sphingosine-1-phosphateBiomolecules.  10:1-23. 2020
2020 Lipid mediators and biomarkers associated with type 1 diabetes developmentJCI Insight.  5. 2020
2020 Macrophage polarization is linked to Ca2+-independent phospholipase A2β-derived lipids and cross-cell signaling in miceJournal of Lipid Research.  61:143-148. 2020
2019 Promiscuity of the catalytic Sec7 domain within the guanine nucleotide exchange factor GBF1 in ARF activation, Golgi homeostasis, and effector recruitmentMolecular Biology of the Cell.  30:1523-1535. 2019
2019 iPLA 2 β and its role in male fertility, neurological disorders, metabolic disorders, and inflammation 2019
2019 β-Lactones: A Novel Class of Ca 2+ -Independent Phospholipase A 2 (Group VIA iPLA 2 ) Inhibitors with the Ability To Inhibit β-Cell ApoptosisJournal of Medicinal Chemistry.  62:2916-2927. 2019
2017 Analyses of Calcium-Independent Phospholipase A2beta (iPLA2β) in Biological SystemsMethods in Enzymology.  583:119-141. 2017
2016 Polarization of macrophages toward M2 phenotype is favored by reduction in iPLA2β Group VIA phospholipase a2Journal of Biological Chemistry.  291:23268-23281. 2016
2016 Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)Autophagy.  12:1-222. 2016
2016 Erratum to: Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition) (Autophagy, 12, 1, 1-222, 10.1080/15548627.2015.1100356Autophagy.  12:443. 2016
2015 Calcium-independent phospholipases A2 and their roles in biological processes and diseasesJournal of Lipid Research.  56:1643-1668. 2015
2015 Group VIA phospholipase a2 (iPLA2β) modulates Bcl-x 5′-splice site selection and suppresses anti-apoptotic Bcl-x(L) in β-cellsJournal of Biological Chemistry.  290:11021-11031. 2015
2015 Inhibition of Ca2+-independent phospholipase A2β (iPLA2β) ameliorates islet infiltration and incidence of diabetes in NOD miceDiabetes.  64:541-554. 2015
2014 Evidence of contribution of iPLA2β-mediated events during islet β-cell apoptosis due to proinflammatory cytokines suggests a role for iPLA2β in T1D development 2014
2014 High glucose exposure promotes activation of protein phosphatase 2A in rodent islets and INS-1 832/13 β-cells by increasing the posttranslational carboxylmethylation of its catalytic subunit 2014
2014 Novel effects of Brefeldin A (BFA) in signaling through the insulin receptor (IR) pathway and regulating FoxO1-mediated transcription.Cellular Logistics.  4:e27732. 2014
2013 Vitamin D and calcium-sensing receptor polymorphisms differentially associate with resting energy expenditure in peripubertal childrenJournal of Bone and Mineral Metabolism.  31:695-702. 2013
2013 Dysfunctional mitochondrial bioenergetics and oxidative stress in Akita+/Ins2-derived β-cells 2013
2013 Characterization of FKGK18 as Inhibitor of Group VIA Ca2+-Independent Phospholipase A2 (iPLA2β): Candidate Drug for Preventing Beta-Cell Apoptosis and DiabetesPLoS One.  8. 2013
2013 Genetic modulation of islet β-cell iPLA2β expression provides evidence for its impact on β-cell apoptosis and autophagyIslets.  5:29-44. 2013
2012 Role of calcium-independent phospholipase A2β in human pancreatic islet β-cell apoptosis 2012
2012 Carbonylation induces heterogeneity in cardiac ryanodine receptor function in diabetes mellitusMolecular Pharmacology.  82:383-399. 2012
2010 Group VIA Ca2+-independent phospholipase A2 (iPLA2β) and its role in β-cell programmed cell deathBiochimie.  92:627-637. 2010
2010 Evidence for proteolytic processing and stimulated organelle redistribution of iPLA2β 2010
2010 HIV-protease inhibitors suppress skeletal muscle fatty acid oxidation by reducing CD36 and CPT1 fatty acid transporters 2010
2010 Spontaneous development of endoplasmic reticulum stress that can lead to diabetes mellitus is associated with higher calcium-independent phospholipase A2 expression: A role for regulation by SREBP-1Journal of Biological Chemistry.  285:6693-6705. 2010
2010 A link between endoplasmic reticulum stress-induced β-cell apoptosis and the group VIA Ca2+-independent phospholipase A2 (iPLA2β) 2010
2009 Protease inhibitors used in the treatment of HIV+ induce β-cell apoptosis via the mitochondrial pathway and compromise insulin secretion 2009
2008 Calcium-independent phospholipase A2 (iPLA2β)- mediated ceramide generation plays a key role in the cross-talk between the endoplasmic reticulum (ER) and mitochondria during ER stress-induced insulin-secreting cell apoptosisJournal of Biological Chemistry.  283:34819-34832. 2008
2008 Skeletal muscle group VIA phospholipase A2 (iPLA 2β): Expression and role in fatty acid oxidationBiochemistry.  47:12241-12249. 2008
2008 HIV-protease inhibitors induce expression of suppressor of cytokine signaling-1 in insulin-sensitive tissues and promote insulin resistance and type 2 diabetes mellitus 2008
2008 Age-related changes in bone morphology are accelerated in group VIA Phospholipase A2 (iPLA2β)-null miceAmerican Journal of Pathology.  172:868-881. 2008
2007 Attenuated free cholesterol loading-induced apoptosis but preserved phospholipid composition of peritoneal macrophages from mice that do not express group VIA phospholipase A2Journal of Biological Chemistry.  282:27100-27114. 2007
2007 The group VIA calcium-independent phospholipase A2 participates in ER stress-induced INS-1 insulinoma cell apoptosis by promoting ceramide generation via hydrolysis of sphingomyelins by neutral sphingomyelinaseBiochemistry.  46:10170-10185. 2007
2006 Insulin secretory responses and phospholipid composition of pancreatic islets from mice that do not express Group VIA phospholipase A2 and effects of metabolic stress on glucose homeostasisJournal of Biological Chemistry.  281:20958-20973. 2006
2006 Effects of biological oxidants on the catalytic activity and structure of group VIA phospholipase A2Biochemistry.  45:6392-6406. 2006
2006 A bromoenol lactone suicide substrate inactivates group VIA phospholipase A2 by generating a diffiusible bromomethyl keto acid that alkylates cysteine thiolsBiochemistry.  45:1061-1073. 2006
2006 Effects of stable suppression of group VIA phospholipase A2 expression on phospholipid content and composition, insulin secretion, and proliferation of INS-1 insulinoma cellsJournal of Biological Chemistry.  281:187-198. 2006
2005 Group VIA phospholipase A2 forms a signaling complex with the calcium/calmodulin-dependent protein kinase IIβ expressed in pancreatic islet β-cellsJournal of Biological Chemistry.  280:6840-6849. 2005
2004 Characterization of N-Terminal processing of group VIA phospholipase A 2 and of potential cleavage sites of amyloid precursor protein constructs by automated identification of signature peptides in LC/MS/MS analyses of proteolytic digestsJournal of the American Society for Mass Spectrometry.  15:1780-1793. 2004
2004 The expression and function of a group VIA calcium-independent phospholipase A2 (iPLA2β) in β-cellsCanadian Journal of Physiology and Pharmacology.  82:824-832. 2004
2004 Male mice that do not express Group VIA Phospholipase A2 produce spermatozoa with impaired motility and have greatly reduced fertilityJournal of Biological Chemistry.  279:38194-38200. 2004
2004 Apoptosis of Insulin-Secreting Cells Induced by Endoplasmic Reticulum Stress Is Amplified by Overexpression of Group VIA Calcium-Independent Phospholipase A2 (iPLA2β) and Suppressed by Inhibition of iPLA2βBiochemistry.  43:918-930. 2004
2004 Beta-cell calcium-independent group VIA phospholipase A(2) (iPLA(2)beta): tracking iPLA(2)beta movements in response to stimulation with insulin secretagogues in INS-1 cells.Diabetes.  53 Suppl 1:S186-S189. 2004
2004 Islet Complex Lipids: Involvement in the Actions of Group VIA Calcium-Independent Phospholipase A2 in β-CellsDiabetes.  53. 2004
2003 Pancreatic Islets and Insulinoma Cells Express a Novel Isoform of Group VIA Phospholipase A2 (iPLA2β) that Participates in Glucose-Stimulated Insulin Secretion and Is Not Produced by Alternate Splicing of the iPLA2β TranscriptBiochemistry.  42:13929-13940. 2003
2002 Delta6-, Stearoyl CoA-, and Delta5-desaturase enzymes are expressed in beta-cells and are altered by increases in exogenous PUFA concentrations. 2002
2001 Studies of Insulin Secretory Responses and of Arachidonic Acid Incorporation into Phospholipids of Stably Transfected Insulinoma Cells That Overexpress Group VIA Phospholipase A2 (iPLA2β) Indicate a Signaling Rather Than a Housekeeping Role for iPLA2βJournal of Biological Chemistry.  276:13198-13208. 2001
2001 Studies of phospholipid metabolism, proliferation, and secretion of stably transfected insulinoma cells that overexpress group VIA phospholipase A2Lipids.  36:689-700. 2001
2000 Electrospray ionization/mass spectrometric analyses of human promonocytic U937 cell glycerolipids and evidence that differentiation is associated with membrane lipid composition changes that facilitate phospholipase A2 activationJournal of Biological Chemistry.  275:16579-16589. 2000
2000 Electrospray ionization mass spectrometric analyses of phospholipids from INS-1 insulinoma cells: Comparison to pancreatic islets and effects of fatty acid supplementation on phospholipid composition and insulin secretion 2000
2000 Electrospray ionization mass spectrometric analyses of changes in tissue phospholipid molecular species during the evolution of hyperlipidemia and hyperglycemia in Zucker diabetic fatty ratsLipids.  35:839-852. 2000
1999 Studies of the role of group VI phospholipase A2 in fatty acid incorporation, phospholipid remodeling, lysophosphatidylcholine generation, and secretagogue-induced arachidonic acid release in pancreatic islets and insulinoma cellsJournal of Biological Chemistry.  274:13915-13927. 1999
1999 Human pancreatic islets express mRNA species encoding two distinct catalytically active isoforms of group VI phospholipase A2 (iPLA2) that arise from an exon-skipping mechanism of alternative splicing of the transcript from the iPLA2 gene on chromosome 22q13.1Journal of Biological Chemistry.  274:9607-9616. 1999
1998 Isolation of human skeletal muscle myosin heavy chain and actin for measurement of fractional synthesis rates.American Journal of Physiology.  275:E1092-E1099. 1998
1998 Reconstitution of membrane fusion between pancreatic islet secretory granules and plasma membranes: Catalysis by a protein constituent recognized by monoclonal antibodies directed against glyceraldehyde-3-phosphate dehydrogenase 1998
1998 Mass Spectrometric Evidence That Agents That Cause Loss of Ca2+ from Intracellular Compartments Induce Hydrolysis of Arachidonic Acid from Pancreatic Islet Membrane Phospholipids by a Mechanism That Does Not Require a Rise in Cytosolic Ca2+ Concentration* * This work was supported by U.S. Public Health Service grants PO1-HL57278, P41-RR-00954, and S10-RR-11260 and by an American Diabetes Association Career Development Award (S.R.).Endocrinology.  139:4073-4085. 1998
1998 Cloning and expression of a group IV cytosolic Ca2+-dependent phospholipase A2 from rat pancreatic islets. Comparison of the expressed activity with that of an islet group VI cytosolic Ca2+-independent phospholipase A2 1998
1998 Electrospray ionization mass spectrometric analyses of phospholipids from rat and human pancreatic islets and subcellular membranes: Comparison to other tissues and implications for membrane fusion in insulin exocytosisBiochemistry.  37:4553-4567. 1998
1998 Type IB secretory phospholipase A2 is contained in insulin secretory granules of pancreatic islet β-cells and is co-secreted with insulin from glucose-stimulated islets 1998
1998 Mass spectrometric evidence that agents that cause loss of Ca2+ from intracellular compartments induce hydrolysis of arachidonic acid from pancreatic islet membrane phospholipids by a mechanism that does not require a rise in cytosolic Ca2+ concentration 1998
1997 Effects of arachidonyltrifluoromethyl ketone on cytosolic [Ca2+] in HIT insulinoma cellsJournal of lipid mediators and cell signalling.  17:65-70. 1997
1997 Interleukin-1 reduces the glycolytic utilization of glucose by pancreatic islets and reduces glucokinase mRNA content and protein synthesis by a nitric oxide-dependent mechanismJournal of Biological Chemistry.  272:17827-17835. 1997
1997 Pancreatic islets express a Ca2+-independent phospholipase A2 enzyme that contains a repeated structural motif homologous to the integral membrane protein binding domain of ankyrinJournal of Biological Chemistry.  272:11118-11127. 1997
1997 Glucose-responsitivity and expression of an ATP-stimulatable, Ca2+-independent phospholipase A2 enzyme in clonal insulinoma cell lines 1997
1996 Characterization of expression of phosphofructokinase isoforms in isolated rat pancreatic islets and purified beta cells and cloning and expression of the rat phosphofructokinase-A isoform 1996
1996 Evidence for association of an ATP-stimulatable Ca2+-independent phospholipase A2 from pancreatic islets and HIT insulinoma cells with a phosphofructokinase-like proteinBiochemistry.  35:5464-5471. 1996
1996 Interleukin-1 enhances pancreatic islet arachidonic acid 12-lipoxygenase product generation by increasing substrate availability through a nitric oxide-dependent mechanism*Journal of Biological Chemistry.  271:1029-1042. 1996
1995 Pancreatic islet cells express a family of inwardly rectifying K+ channel subunits which interact to form G-protein-activated channelsJournal of Biological Chemistry.  270:26086-26091. 1995
1994 Characterization of an ATP-Stimulatable Ca2+-Independent Phospholipase A2 from Clonal Insulin-Secreting HIT Cells and Rat Pancreatic Islets: A Possible Molecular Component of the β-Cell Fuel SensorBiochemistry.  33:7442-7452. 1994
1994 omega-Conotoxin inhibits glucose- and arachidonic acid-induced rises in intracellular [Ca2+] in rat pancreatic islet beta-cells.Cell Calcium.  15:259-264. 1994
1993 Biochemical evidence for nitric oxide formation from streptozotocin in isolated pancreatic isletsBiochemical and Biophysical Research Communications.  197:1458-1464. 1993
1993 Amplification of insulin secretion by lipid messengersDiabetes.  42:367-374. 1993
1993 Arachidonic acid release from aortic smooth muscle cells induced by [Arg8]vasopressin is largely mediated by calcium-independent phospholipase A2Journal of Biological Chemistry.  268:20713-20716. 1993
1993 Inhibition of Arachidonate Release by Secretagogue-Stimulated Pancreatic Islets Suppresses both Insulin Secretion and the Rise in β-Cell Cytosolic Calcium Ion ConcentrationBiochemistry.  32:337-346. 1993
1993 Mass Spectrometric Characterization of Arachidonate-Containing Plasmalogens in Human Pancreatic Islets and in Rat Islet β-Cells and Subcellular MembranesBiochemistry.  32:13499-13509. 1993
1993 Mass Spectrometric Identification and Quantitation of Arachidonate-Containing Phospholipids in Pancreatic Islets: Prominence of Plasmenylethanolamine Molecular SpeciesBiochemistry.  32:5339-5351. 1993
1993 Rat and Human Pancreatic Islet Cells Contain a Calcium Ion Independent Phospholipase A2 Activity Selective for Hydrolysis of Arachidonate Which Is Stimulated by Adenosine Triphosphate and Is Specifically Localized to Islet β-CellsBiochemistry.  32:327-336. 1993
1992 Selective expression of an arachidonate 12-lipoxygenase by pancreatic islet beta-cells.American Journal of Physiology.  263:E828-E836. 1992
1992 Arachidonic acid metabolism in isolated pancreatic islets VI. Carbohydrate insulin secretagogues must be metabolized to induce eicosanoid release 1992
1992 Arachidonic acid induces an increase in the cytosolic calcium concentration in single pancreatic islet beta cellsBiochemical and Biophysical Research Communications.  184:647-653. 1992
1992 Quantification of distinct molecular species of the 2-lyso metabolite of platelet-activating factor by gas chromatography-negative-ion chemical ionization mass spectrometryJournal of Chromatography - Biomedical Applications.  575:183-196. 1992


Year Title Altmetric
1996 Phospholipid hydrolysis in pancreatic islet beta cells and the regulation of insulin secretion.  Ed. 1.  1996

Research Overview

  • Our lab studies Diabetes mellitus (DM), the most prevalent human metabolic disease; it results from loss and/or dysfunction of b-cells in pancreatic islets. Accumulating evidence suggests that ß-cell apoptosis contributes to the pathophysiology in both types 1 and 2 diabetes mellitus. We identified the participation of a Ca2+-independent phospholipase A2 in ß-cell apoptosis and the goals of this project are to understand the mechanism by which lipid mediators contribute to ß-cell death. Recent studies suggest an interplay between pancreatic islets and osteoblasts and our goal is to elucidate the signaling pathways that link these two “endocrine” organs. Bioactive arachidonic acid (AA) metabolites (eicosanoids) generated by the actions of 5-lipoxygenase (5-LO) and cyclooxygenase (COX) are important mediators of bone remodeling. The introduction of PIs in 1995 has resulted in marked decreases in mortality among HIV+ patients from 30% achieved with RTs combination therapy alone to 8% with the addition of a PI. However, inclusion of PIs in the therapeutic regimen is also associated with peripheral lipoatrophy, visceral adiposity, hyperlipidemia, insulin resistance, hyperglycemia, and overt type 2 diabetes mellitus. Our studies indicate the involvement of a novel signaling cascade in PI-Induced insulin resistance and diabetes and the goals of this project are to describe the mechanism(s) by which chronic PI treatments induce metabolic abnormalities.
  • Principal Investigator On

  • Calcium-Independent Pla2beta in Beta-Cell Apoptosis  awarded by National Institute of Diabetes and Digestive and Kidney Diseases/NIH/DHHS
  • Contribution of ß-Cell- & Immune Cell-Derived Lipids to ß-Cell Death and Diabetes  awarded by National Institute of Diabetes and Digestive and Kidney Diseases/NIH/DHHS
  • Countering Lipid-Mediated Immune Response to Prevent Beta-Cell Death and TIDM  awarded by Iacocca Foundation
  • Exploiting CRISPR Strategy to Modify T-Cell Lipid Signaling and Mitigate T1D Development  awarded by JUVENILE DIABETES RESEARCH FOUNDATION, USA
  • Exploiting iPLA2ß-Modified Macrophages as Immunotherapy for T1D  awarded by National Institute of Allergy and Infectious Diseases/NIH/DHHS
  • Importance Of Immune-Cell Lipid Signaling In Events Leading To Type 1 Diabetes  awarded by National Institute of Allergy and Infectious Diseases/NIH/DHHS
  • Novel Combination Regimen Therapy to Modulate Pro- and Anti-Inflammatory Lipid Signaling to Counter T1D  awarded by JUVENILE DIABETES RESEARCH FOUNDATION, USA
  • Targeting Prostaglandin F-series Lipids to Counter Beta-Cell-Death and T1D Development  awarded by JUVENILE DIABETES RESEARCH FOUNDATION, USA
  • The Integrated Stress Response in Human Islets During Early T1D  awarded by University of Chicago ^
  • The Involvement of iPLA2b-Derived Lipid Signaling in Endoplasmic Reticulum Ca2+ Leak Via Translocon in ß-cells  awarded by CAYMAN BIOMEDICAL RESEARCH INSTITUTE
  • iPLA2beta-Dependent Ceramide Generation & Mitochondrial Activation in Beta-Cell Apoptosis  awarded by American Diabetes Association, Inc.
  • iPLA2beta-Mediated Alternative Splicing and Cell Death in Type 1 Diabetes  awarded by University of Virginia ^
  • iPLA2beta-Mediated Alternative Splicing and ß-cell Death in Type 1 Diabetes  awarded by UNIVERSITY OF SOUTH FLORIDA
  • Full Name

  • Sasanka Ramanadham