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Almeida MGMD, Arêdes DS, Majerowicz D, Færgeman NJ, Knudsen J, Gondim KC. Expression of acyl-CoA-binding protein 5 from Rhodnius prolixus and its inhibition by RNA interference. PLoS One 2020; 15:e0227685. [PMID: 31935250 PMCID: PMC6959561 DOI: 10.1371/journal.pone.0227685] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 12/24/2019] [Indexed: 12/03/2022] Open
Abstract
The acyl-CoA-binding proteins (ACBP) act by regulating the availability of acyl-CoA in the cytoplasm and must have essential functions in lipid metabolism. The genome of the kissing-bug Rhodnius prolixus encodes five proteins of this family, but little is known about them. In this study we investigated the expression and function of RpACBP-5. Feeding induced RpACBP-5 gene expression in the posterior midgut, and an increase of about four times was observed two days after the blood meal. However, the amount of protein, which was only detected in this organ, did not change during digestion. The RpACBP-5 gene was also highly expressed in pre-vitellogenic and vitellogenic oocytes. Recombinant RpACBP-5 was shown to bind to acyl-CoA of different lengths, and it exhibited nanomolar affinity to lauroyl-CoA in an isothermal titration assay, indicating that RpACBP-5 is a functional ACBP. RpACBP-5 knockdown by RNA interference did not affect digestion, egg laying and hatching, survival, or accumulation of triacylglycerol in the fat body and oocytes. Similarly, double knockdown of RpACBP-1 and RpACBP-5 did not alter egg laying and hatching, survival, accumulation of triacylglycerol in the fat body and oocytes, or the neutral lipid composition of the posterior midgut or hemolymph. These results show that RpACBP-5 is a functional ACBP but indicate that the lack of a detectable phenotype in the knockdown insects may be a consequence of functional overlap of the proteins of the ACBP family found in the insect.
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Affiliation(s)
- Muriel G. M. D. Almeida
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Daniela S. Arêdes
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - David Majerowicz
- Institut for Biokemi og Molekylær Biologi, Syddansk Universitet, Odense, Denmark
- Faculdade de Farmácia, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
| | - Nils J. Færgeman
- Institut for Biokemi og Molekylær Biologi, Syddansk Universitet, Odense, Denmark
| | - Jens Knudsen
- Institut for Biokemi og Molekylær Biologi, Syddansk Universitet, Odense, Denmark
| | - Katia C. Gondim
- Instituto de Bioquímica Médica Leopoldo de Meis, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
- * E-mail:
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Inhibitors of Fatty Acid Synthesis Induce PPAR α -Regulated Fatty Acid β -Oxidative Genes: Synergistic Roles of L-FABP and Glucose. PPAR Res 2013; 2013:865604. [PMID: 23533380 PMCID: PMC3600304 DOI: 10.1155/2013/865604] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Accepted: 12/21/2012] [Indexed: 12/21/2022] Open
Abstract
While TOFA (acetyl CoA carboxylase inhibitor) and C75 (fatty acid synthase inhibitor) prevent lipid accumulation by inhibiting fatty acid synthesis, the mechanism of action is not simply accounted for by inhibition of the enzymes alone.
Liver fatty acid binding protein (L-FABP), a mediator of long chain fatty acid signaling to peroxisome
proliferator-activated receptor-α (PPARα) in the nucleus, was found to bind
TOFA and its activated CoA thioester, TOFyl-CoA, with high affinity while binding C75 and C75-CoA
with lower affinity. Binding of TOFA and C75-CoA significantly altered L-FABP secondary structure. High (20 mM) but not physiological
(6 mM) glucose conferred on both TOFA and C75 the ability to induce PPARα transcription of the fatty
acid β-oxidative enzymes CPT1A, CPT2, and ACOX1 in cultured primary hepatocytes from wild-type (WT) mice.
However, L-FABP gene ablation abolished the effects of TOFA and C75 in the context of high glucose. These effects were not associated
with an increased cellular level of unesterified fatty acids but rather by increased intracellular glucose. These findings suggested that L-FABP may function as an intracellular fatty acid synthesis inhibitor binding protein
facilitating TOFA and C75-mediated induction of PPARα in the context of high glucose at levels similar to those in uncontrolled diabetes.
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Hostetler HA, Balanarasimha M, Huang H, Kelzer MS, Kaliappan A, Kier AB, Schroeder F. Glucose regulates fatty acid binding protein interaction with lipids and peroxisome proliferator-activated receptor α. J Lipid Res 2010; 51:3103-16. [PMID: 20628144 DOI: 10.1194/jlr.m005041] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Although the pathophysiology of diabetes is characterized by elevated levels of glucose and long-chain fatty acids (LCFA), nuclear mechanisms linking glucose and LCFA metabolism are poorly understood. As the liver fatty acid binding protein (L-FABP) shuttles LCFA to the nucleus, where L-FABP directly interacts with peroxisome proliferator-activated receptor-α (PPARα), the effect of glucose on these processes was examined. In vitro studies showed that L-FABP strongly bound glucose and glucose-1-phosphate (K(d) = 103 ± 19 nM and K(d) = 20 ± 3 nM, respectively), resulting in altered L-FABP conformation, increased affinity for lipid ligands, and enhanced interaction with PPARα. In living cells, glucose stimulated cellular uptake and nuclear localization of a nonmetabolizable fluorescent fatty acid analog (BODIPY C-16), particularly in the presence of L-FABP. These data suggest for the first time a direct role of glucose in facilitating L-FABP-mediated uptake and distribution of lipidic ligands to the nucleus for regulation of PPARα transcriptional activity.
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Affiliation(s)
- Heather A Hostetler
- Departments of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX, USA
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Li C, Reddy TRK, Fischer PM, Dekker LV. A Cy5-labeled S100A10 tracer used to identify inhibitors of the protein interaction with annexin A2. Assay Drug Dev Technol 2010; 8:85-95. [PMID: 20085458 DOI: 10.1089/adt.2009.0218] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Protein-protein interactions are increasingly of interest as targets in small-molecule drug discovery. The interaction between the Ca2+- and phospholipid-binding protein Annexin A2 and its binding partner S100A10 has been implicated in angiogenesis and cancer metastasis. Here, we present a methodology to screen for inhibitors of this protein interaction. We developed a Cy5-labeled S100A10 tracer and showed by circular dichroism spectroscopy that the secondary structure is indistinguishable from that of non-labeled S100A10. This tracer was used to develop a binding assay based upon fluorescence resonance energy transfer to a Cy3-labeled Annexin A2 peptide ligand. The binding parameters matched those for unlabeled components as observed by equilibrium dialysis, which we determined separately, as well as those determined by isothermal titration calorimetry. Binding of labeled and unlabeled peptide was specific and mutually competitive. We used this assay for screening a small compound library derived by computational interrogation of the S100A10-binding pocket. Hits were obtained with IC(50) values in range of the IC(50) of the cognate Annexin A2 peptide ligand. Hits were subjected to an exact parallel assay measuring an unrelated protein-protein interaction (antigen-antibody). In this way, we identified genuine hits that inhibited the interaction between S100A10 and Annexin A2 but do not affect the fluorescence readout. These compounds are potentially of interest as candidates for further analysis and medical chemistry exploration. The simple assay format described here can be employed in early-stage exploration of other protein-protein interaction targets.
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Affiliation(s)
- Chan Li
- School of Pharmacy, Centre for Biomolecular Sciences, University of Nottingham, United Kingdom
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Hostetler HA, McIntosh AL, Atshaves BP, Storey SM, Payne HR, Kier AB, Schroeder F. L-FABP directly interacts with PPARalpha in cultured primary hepatocytes. J Lipid Res 2009; 50:1663-75. [PMID: 19289416 DOI: 10.1194/jlr.m900058-jlr200] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although studies with liver type fatty acid binding protein (L-FABP) gene ablated mice demonstrate a physiological role for L-FABP in hepatic fatty acid metabolism, little is known about the mechanisms whereby L-FABP elicits these effects. Studies indicate that L-FABP may function to shuttle lipids to the nucleus, thereby increasing the availability of ligands of nuclear receptors, such as peroxisome proliferator-activated receptor-alpha (PPARalpha). The data herein suggest that such mechanisms involve direct interaction of L-FABP with PPARalpha. L-FABP was shown to directly interact with PPARalpha in vitro through co-immunoprecipitation (co-IP) of pure proteins, altered circular dichroic (CD) spectra, and altered fluorescence spectra. In vitro fluorescence resonance energy transfer (FRET) between Cy3-labeled PPARalpha and Cy5-labeled L-FABP proteins showed that these proteins bound with high affinity (Kd approximately 156 nM) and in close proximity (intermolecular distance of 52A). This interaction was further substantiated by co-IP of both proteins from liver homogenates of wild-type mice. Moreover, double immunogold electron microscopy and FRET confocal microscopy of cultured primary hepatocytes showed that L-FABP was in close proximity to PPARalpha (intermolecular distance 40-49A) in vivo. Taken together, these studies were consistent with L-FABP regulating PPARalpha transcriptional activity in hepatocytes through direct interaction with PPARalpha. Our in vitro and imaging experiments demonstrate high affinity, structural molecular interaction of L-FABP with PPARalpha and suggest a functional role for L-FABP interaction with PPARalpha in long chain fatty acid (LCFA) metabolism.
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Affiliation(s)
- Heather A Hostetler
- Department of Physiology and Pharmacology, Texas A&M University, College of Veterinary Medicine and Biomedical Sciences, College Station, TX 77843, USA
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Petrescu AD, Vespa A, Huang H, McIntosh AL, Schroeder F, Kier AB. Fluorescent sterols monitor cell penetrating peptide Pep-1 mediated uptake and intracellular targeting of cargo protein in living cells. BIOCHIMICA ET BIOPHYSICA ACTA 2009; 1788:425-41. [PMID: 18992218 PMCID: PMC2680736 DOI: 10.1016/j.bbamem.2008.09.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2008] [Revised: 08/25/2008] [Accepted: 09/24/2008] [Indexed: 12/15/2022]
Abstract
Although cell-penetrating peptides (CPP) facilitate endocytic uptake of proteins, little is known regarding the extent to which CPPs facilitate protein cargo exit from endocytic vesicles for targeting to other intracellular sites. Since the plasma membrane and less so intracellular membranes contain cholesterol, the fluorescent sterol analogues dansyl-cholestanol (DChol) and dehydroergosterol (DHE) were used to monitor the uptake and intracellular distribution of fluorescent-tagged acyl coenzyme A binding protein (ACBP) into COS-7 cells and rat hepatoma cells. Confocal microscopy colocalized DChol and Texas Red-ACBP (TR-ACBP) with markers for the major endocytosis pathways, especially fluorescent-labeled cholera toxin (marker of ganglioside GM1 in plasma membrane lipid rafts) and dextran (macropinocytosis marker), but less so with transferrin (clathrin-mediated endocytosis marker). These findings were confirmed by multiphoton laser scanning microscopy colocalization of TR-ACBP with DHE (naturally-fluorescent sterol) and by double immunofluorescence labeling of native endogenous ACBP. Serum greatly and Pep-1 further 2.4-fold facilitated uptake of TR-ACBP, but neither altered the relative proportion of TR-ACBP colocalized with membranes/organelles (nearly 80%) vs cytoplasm and/or nucleoplasm (20%). Interestingly, Pep-1 selectively increased TR-ACBP associated with mitochondria while concomitantly decreasing that in endoplasmic reticulum. In summary, fluorescent sterols (DChol, DHE) were useful markers for comparing the distributions of both transported and endogenous proteins. Pep-1 modestly enhanced the translocation and altered the intracellular targeting of exogenous-delivered (TR-ACBP) in living cells.
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Affiliation(s)
- Anca D. Petrescu
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843-4467
| | - Aude Vespa
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843-4467
| | - Huan Huang
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843-4467
| | - Avery L. McIntosh
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843-4467
| | - Friedhelm Schroeder
- Department of Pathobiology, Texas A&M University, TVMC, College Station, TX 77843-4467
| | - Ann B. Kier
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4467
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Schroeder F, Petrescu AD, Huang H, Atshaves BP, McIntosh AL, Martin GG, Hostetler HA, Vespa A, Landrock D, Landrock KK, Payne HR, Kier AB. Role of fatty acid binding proteins and long chain fatty acids in modulating nuclear receptors and gene transcription. Lipids 2007; 43:1-17. [PMID: 17882463 DOI: 10.1007/s11745-007-3111-z] [Citation(s) in RCA: 171] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2007] [Accepted: 07/26/2007] [Indexed: 12/16/2022]
Abstract
Abnormal energy regulation may significantly contribute to the pathogenesis of obesity, diabetes mellitus, cardiovascular disease, and cancer. For rapid control of energy homeostasis, allosteric and posttranslational events activate or alter activity of key metabolic enzymes. For longer impact, transcriptional regulation is more effective, especially in response to nutrients such as long chain fatty acids (LCFA). Recent advances provide insights into how poorly water-soluble lipid nutrients [LCFA; retinoic acid (RA)] and their metabolites (long chain fatty acyl Coenzyme A, LCFA-CoA) reach nuclei, bind their cognate ligand-activated receptors, and regulate transcription for signaling lipid and glucose catabolism or storage: (i) while serum and cytoplasmic LCFA levels are in the 200 mircroM-mM range, real-time imaging recently revealed that LCFA and LCFA-CoA are also located within nuclei (nM range); (ii) sensitive fluorescence binding assays show that LCFA-activated nuclear receptors [peroxisome proliferator-activated receptor-alpha (PPARalpha) and hepatocyte nuclear factor 4alpha (HNF4alpha)] exhibit high affinity (low nM KdS) for LCFA (PPARalpha) and/or LCFA-CoA (PPARalpha, HNF4alpha)-in the same range as nuclear levels of these ligands; (iii) live and fixed cell immunolabeling and imaging revealed that some cytoplasmic lipid binding proteins [liver fatty acid binding protein (L-FABP), acyl CoA binding protein (ACBP), cellular retinoic acid binding protein-2 (CRABP-2)] enter nuclei, bind nuclear receptors (PPARalpha, HNF4alpha, CRABP-2), and activate transcription of genes in fatty acid and glucose metabolism; and (iv) studies with gene ablated mice provided physiological relevance of LCFA and LCFA-CoA binding proteins in nuclear signaling. This led to the hypothesis that cytoplasmic lipid binding proteins transfer and channel lipidic ligands into nuclei for initiating nuclear receptor transcriptional activity to provide new lipid nutrient signaling pathways that affect lipid and glucose catabolism and storage.
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Affiliation(s)
- Friedhelm Schroeder
- Department of Physiology and Pharmacology, Texas A&M University, TVMC, College Station, TX 77843-4466, USA.
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