1
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Basu R, Elmendorf AJ, Lorentz B, Mahler CA, Lazzaro O, App B, Zhou S, Yamamoto Y, Suber M, Wann JC, Roh HC, Sheets PL, Johnson TS, Flak JN. Ventromedial hypothalamic nucleus subset stimulates tissue thermogenesis via preoptic area outputs. Mol Metab 2024; 84:101951. [PMID: 38729241 PMCID: PMC11112375 DOI: 10.1016/j.molmet.2024.101951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 04/20/2024] [Accepted: 04/27/2024] [Indexed: 05/12/2024] Open
Abstract
OBJECTIVE Hypothalamic signals potently stimulate energy expenditure by engaging peripheral mechanisms to restore energy homeostasis. Previous studies have identified several critical hypothalamic sites (e.g. preoptic area (POA) and ventromedial hypothalamic nucleus (VMN)) that could be part of an interconnected neurocircuit that controls tissue thermogenesis and essential for body weight control. However, the key neurocircuit that can stimulate energy expenditure has not yet been established. METHODS Here, we investigated the downstream mechanisms by which VMN neurons stimulate adipose tissue thermogenesis. We manipulated subsets of VMN neurons acutely as well as chronically and studied its effect on tissue thermogenesis and body weight control, using Sf1Cre and Adcyap1Cre mice and measured physiological parameters under both high-fat diet and standard chow diet conditions. To determine the node efferent to these VMN neurons, that is involved in modulating energy expenditure, we employed electrophysiology and optogenetics experiments combined with measurements using tissue-implantable temperature microchips. RESULTS Activation of the VMN neurons that express the steroidogenic factor 1 (Sf1; VMNSf1 neurons) reduced body weight, adiposity and increased energy expenditure in diet-induced obese mice. This function is likely mediated, at least in part, by the release of the pituitary adenylate cyclase-activating polypeptide (PACAP; encoded by the Adcyap1 gene) by the VMN neurons, since we previously demonstrated that PACAP, at the VMN, plays a key role in energy expenditure control. Thus, we then shifted focus to the subpopulation of VMNSf1 neurons that contain the neuropeptide PACAP (VMNPACAP neurons). Since the VMN neurons do not directly project to the peripheral tissues, we traced the location of the VMNPACAP neurons' efferents. We identified that VMNPACAP neurons project to and activate neurons in the caudal regions of the POA whereby these projections stimulate tissue thermogenesis in brown and beige adipose tissue. We demonstrated that selective activation of caudal POA projections from VMNPACAP neurons induces tissue thermogenesis, most potently in negative energy balance and activating these projections lead to some similar, but mostly unique, patterns of gene expression in brown and beige tissue. Finally, we demonstrated that the activation of the VMNPACAP neurons' efferents that lie at the caudal POA are necessary for inducing tissue thermogenesis in brown and beige adipose tissue. CONCLUSIONS These data indicate that VMNPACAP connections with the caudal POA neurons impact adipose tissue function and are important for induction of tissue thermogenesis. Our data suggests that the VMNPACAP → caudal POA neurocircuit and its components are critical for controlling energy balance by activating energy expenditure and body weight control.
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Affiliation(s)
- Rashmita Basu
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA; Lilly Diabetes Research Center, Indiana Biosciences Research Institute, Indianapolis, IN, USA
| | - Andrew J Elmendorf
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA; Lilly Diabetes Research Center, Indiana Biosciences Research Institute, Indianapolis, IN, USA
| | - Betty Lorentz
- Lilly Diabetes Research Center, Indiana Biosciences Research Institute, Indianapolis, IN, USA
| | - Connor A Mahler
- Lilly Diabetes Research Center, Indiana Biosciences Research Institute, Indianapolis, IN, USA
| | - Olivia Lazzaro
- Lilly Diabetes Research Center, Indiana Biosciences Research Institute, Indianapolis, IN, USA
| | - Britany App
- Lilly Diabetes Research Center, Indiana Biosciences Research Institute, Indianapolis, IN, USA
| | - Shudi Zhou
- Department of Medical Neuroscience, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Yura Yamamoto
- Lilly Diabetes Research Center, Indiana Biosciences Research Institute, Indianapolis, IN, USA
| | - Mya Suber
- Lilly Diabetes Research Center, Indiana Biosciences Research Institute, Indianapolis, IN, USA
| | - Jamie C Wann
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Hyun Cheol Roh
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Patrick L Sheets
- Department of Medical Neuroscience, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Travis S Johnson
- Lilly Diabetes Research Center, Indiana Biosciences Research Institute, Indianapolis, IN, USA; Department of Biostatistics and Health Data Science, Indiana University School of Medicine, Indianapolis, IN, USA; Melvin and Bren Simon Comprehensive Cancer Centre, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Jonathan N Flak
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA; Lilly Diabetes Research Center, Indiana Biosciences Research Institute, Indianapolis, IN, USA.
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2
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Gandhi SA, Parveen S, Alduhailan M, Tripathi R, Junedi N, Saqallah M, Sanders MA, Hoffmann PM, Truex K, Granneman JG, Kelly CV. Methods for making and observing model lipid droplets. CELL REPORTS METHODS 2024; 4:100774. [PMID: 38749444 PMCID: PMC11133809 DOI: 10.1016/j.crmeth.2024.100774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 01/30/2024] [Accepted: 04/19/2024] [Indexed: 05/23/2024]
Abstract
We present methods for making and testing the membrane biophysics of model lipid droplets (LDs). Methods are described for imaging LDs ranging in size from 0.1 to 40 μm in diameter with high-resolution microscopy and spectroscopy. With known LD compositions, membrane binding, sorting, diffusion, and tension were measured via fluorescence correlation spectroscopy (FCS), fluorescence recovery after photobleaching (FRAP), fluorescence lifetime imaging microscopy (FLIM), atomic force microscopy (AFM), and imaging flow cytometry. Additionally, a custom, small-volume pendant droplet tensiometer is described and used to measure the association of phospholipids to the LD surface. These complementary, cross-validating methods of measuring LD membrane behavior reveal the interplay of biophysical processes on lipid droplet monolayers.
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Affiliation(s)
- Sonali A Gandhi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Shahnaz Parveen
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Munirah Alduhailan
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Ramesh Tripathi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Nasser Junedi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Mohammad Saqallah
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA
| | - Matthew A Sanders
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI 40201, USA; Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | - Peter M Hoffmann
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA; Physical Sciences Department, Embry-Riddle Aeronautical University, Daytona Beach, FL 32114, USA
| | - Katherine Truex
- Department of Physics, United States Naval Academy, Annapolis, MD 21402, USA
| | - James G Granneman
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI 40201, USA; Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI 48201, USA
| | - Christopher V Kelly
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48201, USA; Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI 48201, USA.
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3
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Kohlmayr JM, Grabner GF, Nusser A, Höll A, Manojlović V, Halwachs B, Masser S, Jany-Luig E, Engelke H, Zimmermann R, Stelzl U. Mutational scanning pinpoints distinct binding sites of key ATGL regulators in lipolysis. Nat Commun 2024; 15:2516. [PMID: 38514628 PMCID: PMC10958042 DOI: 10.1038/s41467-024-46937-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 03/14/2024] [Indexed: 03/23/2024] Open
Abstract
ATGL is a key enzyme in intracellular lipolysis and plays an important role in metabolic and cardiovascular diseases. ATGL is tightly regulated by a known set of protein-protein interaction partners with activating or inhibiting functions in the control of lipolysis. Here, we use deep mutational protein interaction perturbation scanning and generate comprehensive profiles of single amino acid variants that affect the interactions of ATGL with its regulatory partners: CGI-58, G0S2, PLIN1, PLIN5 and CIDEC. Twenty-three ATGL amino acid variants yield a specific interaction perturbation pattern when validated in co-immunoprecipitation experiments in mammalian cells. We identify and characterize eleven highly selective ATGL switch mutations which affect the interaction of one of the five partners without affecting the others. Switch mutations thus provide distinct interaction determinants for ATGL's key regulatory proteins at an amino acid resolution. When we test triglyceride hydrolase activity in vitro and lipolysis in cells, the activity patterns of the ATGL switch variants trace to their protein interaction profile. In the context of structural data, the integration of variant binding and activity profiles provides insights into the regulation of lipolysis and the impact of mutations in human disease.
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Affiliation(s)
- Johanna M Kohlmayr
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Gernot F Grabner
- Institute of Molecular Biosciences, Biochemistry, University of Graz, Graz, Austria
- Gottfried Schatz Research Center, Molecular Biology and Biochemistry, Medical University of Graz, Graz, Austria
| | - Anna Nusser
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Anna Höll
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Verina Manojlović
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Bettina Halwachs
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
- Field of Excellence BioHealth - University of Graz, Graz, Austria
| | - Sarah Masser
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Evelyne Jany-Luig
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
| | - Hanna Engelke
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria
- Field of Excellence BioHealth - University of Graz, Graz, Austria
| | - Robert Zimmermann
- Institute of Molecular Biosciences, Biochemistry, University of Graz, Graz, Austria
- Field of Excellence BioHealth - University of Graz, Graz, Austria
- BioTechMed-Graz, Graz, Austria
| | - Ulrich Stelzl
- Institute of Pharmaceutical Sciences, Pharmaceutical Chemistry, University of Graz, Graz, Austria.
- Field of Excellence BioHealth - University of Graz, Graz, Austria.
- BioTechMed-Graz, Graz, Austria.
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4
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Flori L, Piragine E, Calderone V, Testai L. Role of hydrogen sulfide in the regulation of lipid metabolism: Implications on cardiovascular health. Life Sci 2024; 341:122491. [PMID: 38336275 DOI: 10.1016/j.lfs.2024.122491] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 01/29/2024] [Accepted: 02/05/2024] [Indexed: 02/12/2024]
Abstract
The World Health Organization (WHO) defines obesity as an urgency for health and a social emergency. Today around 39 % of people is overweight, of these over 13 % is obese. It is well-consolidated that the adipose cells are deputy to lipid storage under caloric excess; however, despite the classical idea that adipose tissue has exclusively a passive function, now it is known to be deeply involved in the regulation of systemic metabolism in physiological as well as under obesogenic conditions, with consequences on cardiovascular health. Beside two traditional types of adipose cells (white and brown), recently the beige one has been highlighted as the consequence of the healthy remodeling of white adipocytes, confirming their metabolic adaptability. In this direction, pharmacological, nutraceutical and nutrient-based approaches are addressed to positively influence inflammation and metabolism, thus contributing to reduce the obese-associated cardiovascular risk. In this scenario, hydrogen sulfide emerges as a new mediator that may regulate crucial targets involved in the regulation of metabolism. The current evidence demonstrates that hydrogen sulfide may induce peroxisome proliferator activated receptor γ (PPARγ), a crucial mediator of adipogenesis, inhibit the phosphorylation of perlipin-1 (plin-1), a protein implicated in the lipolysis, and finally promote browning process, through the release of irisin from skeletal muscle. The results summarized in this review suggest an important role of hydrogen sulfide in the regulation of metabolism and in the prevention/treatment of obese-associated cardiovascular diseases and propose new insight on the putative mechanisms underlying the release of hydrogen sulfide or its biosynthesis, delineating a further exciting field of application.
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Affiliation(s)
- Lorenzo Flori
- Department of Pharmacy, University of Pisa, via Bonanno, 6-56120 Pisa, Italy.
| | - Eugenia Piragine
- Department of Pharmacy, University of Pisa, via Bonanno, 6-56120 Pisa, Italy.
| | - Vincenzo Calderone
- Department of Pharmacy, University of Pisa, via Bonanno, 6-56120 Pisa, Italy.
| | - Lara Testai
- Department of Pharmacy, University of Pisa, via Bonanno, 6-56120 Pisa, Italy.
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5
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Rahman AA, Butcko AJ, Songyekutu E, Granneman JG, Mottillo EP. Direct effects of adipocyte lipolysis on AMPK through intracellular long-chain acyl-CoA signaling. Sci Rep 2024; 14:19. [PMID: 38167670 PMCID: PMC10761689 DOI: 10.1038/s41598-023-50903-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 12/27/2023] [Indexed: 01/05/2024] Open
Abstract
Long-chain acyl-CoAs (LC-acyl-CoAs) are important intermediary metabolites and are also thought to function as intracellular signaling molecules; however, the direct effects of LC-acyl-CoAs have been difficult to determine in real-time and dissociate from Protein Kinase A (PKA) signaling. Here, we examined the direct role of lipolysis in generating intracellular LC-acyl-CoAs and activating AMPK in white adipocytes by pharmacological activation of ABHD5 (also known as CGI-58), a lipase co-activator. Activation of lipolysis in 3T3-L1 adipocytes independent of PKA with synthetic ABHD5 ligands, resulted in greater activation of AMPK compared to receptor-mediated activation with isoproterenol, a β-adrenergic receptor agonist. Importantly, the effect of pharmacological activation of ABHD5 on AMPK activation was blocked by inhibiting ATGL, the rate-limiting enzyme for triacylglycerol hydrolysis. Utilizing a novel FRET sensor to detect intracellular LC-acyl-CoAs, we demonstrate that stimulation of lipolysis in 3T3-L1 adipocytes increased the production of LC-acyl-CoAs, an effect which was blocked by inhibition of ATGL. Moreover, ATGL inhibition blocked AMPKβ1 S108 phosphorylation, a site required for allosteric regulation. Increasing intracellular LC-acyl-CoAs by removal of BSA in the media and pharmacological inhibition of DGAT1 and 2 resulted in greater activation of AMPK. Finally, inhibiting LC-acyl-CoA generation reduced activation of AMPK; however, did not lower energy charge. Overall, results demonstrate that lipolysis in white adipocytes directly results in allosteric activation of AMPK through the generation of LC-acyl-CoAs.
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Affiliation(s)
- Abir A Rahman
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 6135 Woodward Ave., Detroit, MI, 48202, USA
| | - Andrew J Butcko
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 6135 Woodward Ave., Detroit, MI, 48202, USA
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48202, USA
| | - Emmanuel Songyekutu
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48202, USA
| | - James G Granneman
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, 48202, USA
| | - Emilio P Mottillo
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 6135 Woodward Ave., Detroit, MI, 48202, USA.
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, 48202, USA.
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6
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Gandhi SA, Parveen S, Alduhailan M, Tripathi R, Junedi N, Saqallah M, Sanders MA, Hoffmann PM, Truex K, Granneman JG, Kelly CV. Methods for making and observing model lipid droplets. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.17.549385. [PMID: 37503132 PMCID: PMC10370146 DOI: 10.1101/2023.07.17.549385] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/29/2023]
Abstract
The mechanisms by which the lipid droplet (LD) membrane is remodeled in concert with the activation of lipolysis incorporate a complex interplay of proteins, phospholipids, and neutral lipids. Model LDs (mLDs) provide an isolated, purified system for testing the mechanisms by which the droplet composition, size, shape, and tension affects triglyceride metabolism. Described here are methods of making and testing mLDs ranging from 0.1 to 40 μm diameter with known composition. Methods are described for imaging mLDs with high-resolution microscopy during buffer exchanges for the measurement of membrane binding, diffusion, and tension via fluorescence correlation spectroscopy (FCS), fluorescence recovery after photobleaching (FRAP), fluorescence lifetime imaging microscopy (FLIM), atomic force microscopy (AFM), pendant droplet tensiometry, and imaging flow cytometry. These complementary, cross-validating methods of measuring LD membrane behavior reveal the interplay of biophysical processes in triglyceride metabolism.
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Affiliation(s)
- Sonali A. Gandhi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA 48201
| | - Shahnaz Parveen
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA 48201
| | - Munirah Alduhailan
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA 48201
| | - Ramesh Tripathi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA 48201
| | - Nasser Junedi
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA 48201
| | - Mohammad Saqallah
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA 48201
| | - Matthew A. Sanders
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI, USA 40201
- Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI USA 48201
| | - Peter M. Hoffmann
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA 48201
- Physical Sciences Department, Embry-Riddle Aeronautical University, Daytona Beach, FL, USA 32114
| | - Katherine Truex
- Department of Physics, United States Naval Academy, Annapolis, MD, USA 21402
| | - James G. Granneman
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI, USA 40201
- Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI USA 48201
| | - Christopher V Kelly
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, USA 48201
- Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI USA 48201
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7
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Mottillo EP, Mladenovic-Lucas L, Zhang H, Zhou L, Kelly CV, Ortiz PA, Granneman JG. A FRET sensor for the real-time detection of long chain acyl-CoAs and synthetic ABHD5 ligands. CELL REPORTS METHODS 2023; 3:100394. [PMID: 36936069 PMCID: PMC10014278 DOI: 10.1016/j.crmeth.2023.100394] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 12/19/2022] [Accepted: 01/05/2023] [Indexed: 01/26/2023]
Abstract
Intracellular long-chain acyl-coenzyme As (LC-acyl-CoAs) are thought to be under tight spatial and temporal controls, yet the ability to image LC-acyl-CoAs in live cells is lacking. Here, we developed a fluorescence resonance energy transfer (FRET) sensor for LC-acyl-CoAs based on the allosterically regulated interaction between α/β hydrolase domain-containing 5 (ABHD5) and Perilipin 5. The genetically encoded sensor rapidly detects intracellular LC-acyl-CoAs generated from exogenous and endogenous fatty acids (FAs), as well as synthetic ABHD5 ligands. Stimulation of lipolysis in brown adipocytes elevated intracellular LC-acyl-CoAs in a cyclic fashion, which was eliminated by inhibiting PNPLA2 (ATGL), the major triglyceride lipase. Interestingly, inhibition of LC-acyl-CoA transport into mitochondria elevated intracellular LC-acyl-CoAs and dampened their cycling. Together, these observations reveal an intimate feedback control between LC-acyl-CoA generation from lipolysis and utilization in mitochondria. We anticipate that this sensor will be an important tool to dissect intracellular LC-acyl-CoA dynamics as well to discover novel synthetic ABHD5 ligands.
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Affiliation(s)
- Emilio P. Mottillo
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 6135 Woodward Avenue, Detroit, MI 48202, USA
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
| | - Ljiljana Mladenovic-Lucas
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48202, USA
| | - Huamei Zhang
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48202, USA
| | - Li Zhou
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48202, USA
| | - Christopher V. Kelly
- Department of Physics and Astronomy, Wayne State University, Detroit, MI 48202, USA
| | - Pablo A. Ortiz
- Hypertension and Vascular Research Division, Department of Internal Medicine, Henry Ford Hospital, 6135 Woodward Avenue, Detroit, MI 48202, USA
| | - James G. Granneman
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI 48202, USA
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8
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Markussen LK, Rondini EA, Johansen OS, Madsen JGS, Sustarsic EG, Marcher AB, Hansen JB, Gerhart-Hines Z, Granneman JG, Mandrup S. Lipolysis regulates major transcriptional programs in brown adipocytes. Nat Commun 2022; 13:3956. [PMID: 35803907 PMCID: PMC9270495 DOI: 10.1038/s41467-022-31525-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 06/17/2022] [Indexed: 02/06/2023] Open
Abstract
β-Adrenergic signaling is a core regulator of brown adipocyte function stimulating both lipolysis and transcription of thermogenic genes, thereby expanding the capacity for oxidative metabolism. We have used pharmacological inhibitors and a direct activator of lipolysis to acutely modulate the activity of lipases, thereby enabling us to uncover lipolysis-dependent signaling pathways downstream of β-adrenergic signaling in cultured brown adipocytes. Here we show that induction of lipolysis leads to acute induction of several gene programs and is required for transcriptional regulation by β-adrenergic signals. Using machine-learning algorithms to infer causal transcription factors, we show that PPARs are key mediators of lipolysis-induced activation of genes involved in lipid metabolism and thermogenesis. Importantly, however, lipolysis also activates the unfolded protein response and regulates the core circadian transcriptional machinery independently of PPARs. Our results demonstrate that lipolysis generates important metabolic signals that exert profound pleiotropic effects on transcription and function of cultured brown adipocytes.
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Affiliation(s)
- Lasse K Markussen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
- Center for Adipocyte Signaling (AdipoSign), Odense, Denmark
- Center for Functional Genomics and Tissue Plasticity (ATLAS), Odense, Denmark
| | - Elizabeth A Rondini
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI, USA
| | - Olivia Sveidahl Johansen
- Center for Adipocyte Signaling (AdipoSign), Odense, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
- Embark Biotech ApS, Copenhagen, Denmark
| | - Jesper G S Madsen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
- Center for Functional Genomics and Tissue Plasticity (ATLAS), Odense, Denmark
| | - Elahu G Sustarsic
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Ann-Britt Marcher
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
- Center for Adipocyte Signaling (AdipoSign), Odense, Denmark
- Center for Functional Genomics and Tissue Plasticity (ATLAS), Odense, Denmark
| | - Jacob B Hansen
- Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Zachary Gerhart-Hines
- Center for Adipocyte Signaling (AdipoSign), Odense, Denmark
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
- Embark Biotech ApS, Copenhagen, Denmark
| | - James G Granneman
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI, USA.
| | - Susanne Mandrup
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark.
- Center for Adipocyte Signaling (AdipoSign), Odense, Denmark.
- Center for Functional Genomics and Tissue Plasticity (ATLAS), Odense, Denmark.
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9
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Shahoei R, Pangeni S, Sanders MA, Zhang H, Mladenovic-Lucas L, Roush WR, Halvorsen G, Kelly CV, Granneman JG, Huang YMM. Molecular Modeling of ABHD5 Structure and Ligand Recognition. Front Mol Biosci 2022; 9:935375. [PMID: 35836935 PMCID: PMC9274090 DOI: 10.3389/fmolb.2022.935375] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 06/10/2022] [Indexed: 02/06/2023] Open
Abstract
Alpha/beta hydrolase domain-containing 5 (ABHD5), also termed CGI-58, is the key upstream activator of adipose triglyceride lipase (ATGL), which plays an essential role in lipid metabolism and energy storage. Mutations in ABHD5 disrupt lipolysis and are known to cause the Chanarin-Dorfman syndrome. Despite its importance, the structure of ABHD5 remains unknown. In this work, we combine computational and experimental methods to build a 3D structure of ABHD5. Multiple comparative and machine learning-based homology modeling methods are used to obtain possible models of ABHD5. The results from Gaussian accelerated molecular dynamics and experimental data of the apo models and their mutants are used to select the most likely model. Moreover, ensemble docking is performed on representative conformations of ABHD5 to reveal the binding mechanism of ABHD5 and a series of synthetic ligands. Our study suggests that the ABHD5 models created by deep learning-based methods are the best candidate structures for the ABHD5 protein. The mutations of E41, R116, and G328 disturb the hydrogen bonding network with nearby residues and suppress membrane targeting or ATGL activation. The simulations also reveal that the hydrophobic interactions are responsible for binding sulfonyl piperazine ligands to ABHD5. Our work provides fundamental insight into the structure of ABHD5 and its ligand-binding mode, which can be further applied to develop ABHD5 as a therapeutic target for metabolic disease and cancer.
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Affiliation(s)
- Rezvan Shahoei
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, United States
| | - Susheel Pangeni
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, United States
| | - Matthew A. Sanders
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI, United States
| | - Huamei Zhang
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI, United States
| | - Ljiljana Mladenovic-Lucas
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI, United States
| | - William R. Roush
- Department of Chemistry, Scripps Florida, Jupiter, FL, United States
| | - Geoff Halvorsen
- Department of Chemistry, Scripps Florida, Jupiter, FL, United States
| | - Christopher V. Kelly
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, United States
| | - James G. Granneman
- Center for Molecular Medicine and Genetics, School of Medicine, Wayne State University, Detroit, MI, United States
- Center for Integrative Metabolic and Endocrine Research, School of Medicine, Wayne State University, Detroit, MI, United States
| | - Yu-ming M. Huang
- Department of Physics and Astronomy, Wayne State University, Detroit, MI, United States
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10
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Bononi G, Tuccinardi T, Rizzolio F, Granchi C. α/β-Hydrolase Domain (ABHD) Inhibitors as New Potential Therapeutic Options against Lipid-Related Diseases. J Med Chem 2021; 64:9759-9785. [PMID: 34213320 PMCID: PMC8389839 DOI: 10.1021/acs.jmedchem.1c00624] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Much of the experimental evidence in the literature has linked altered lipid metabolism to severe diseases such as cancer, obesity, cardiovascular pathologies, diabetes, and neurodegenerative diseases. Therefore, targeting key effectors of the dysregulated lipid metabolism may represent an effective strategy to counteract these pathological conditions. In this context, α/β-hydrolase domain (ABHD) enzymes represent an important and diversified family of proteins, which are involved in the complex environment of lipid signaling, metabolism, and regulation. Moreover, some members of the ABHD family play an important role in the endocannabinoid system, being designated to terminate the signaling of the key endocannabinoid regulator 2-arachidonoylglycerol. This Perspective summarizes the research progress in the development of ABHD inhibitors and modulators: design strategies, structure-activity relationships, action mechanisms, and biological studies of the main ABHD ligands will be highlighted.
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Affiliation(s)
- Giulia Bononi
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy
| | - Tiziano Tuccinardi
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy
| | - Flavio Rizzolio
- Pathology Unit, Centro di Riferimento Oncologico di Aviano (CRO) IRCCS, 33081 Aviano, Italy.,Department of Molecular Sciences and Nanosystems, Ca' Foscari University, 30123 Venezia, Italy
| | - Carlotta Granchi
- Department of Pharmacy, University of Pisa, Via Bonanno 6, 56126 Pisa, Italy
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11
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Sveidahl Johansen O, Ma T, Hansen JB, Markussen LK, Schreiber R, Reverte-Salisa L, Dong H, Christensen DP, Sun W, Gnad T, Karavaeva I, Nielsen TS, Kooijman S, Cero C, Dmytriyeva O, Shen Y, Razzoli M, O'Brien SL, Kuipers EN, Nielsen CH, Orchard W, Willemsen N, Jespersen NZ, Lundh M, Sustarsic EG, Hallgren CM, Frost M, McGonigle S, Isidor MS, Broholm C, Pedersen O, Hansen JB, Grarup N, Hansen T, Kjær A, Granneman JG, Babu MM, Calebiro D, Nielsen S, Rydén M, Soccio R, Rensen PCN, Treebak JT, Schwartz TW, Emanuelli B, Bartolomucci A, Pfeifer A, Zechner R, Scheele C, Mandrup S, Gerhart-Hines Z. Lipolysis drives expression of the constitutively active receptor GPR3 to induce adipose thermogenesis. Cell 2021; 184:3502-3518.e33. [PMID: 34048700 PMCID: PMC8238500 DOI: 10.1016/j.cell.2021.04.037] [Citation(s) in RCA: 65] [Impact Index Per Article: 21.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Revised: 02/10/2021] [Accepted: 04/23/2021] [Indexed: 12/19/2022]
Abstract
Thermogenic adipocytes possess a therapeutically appealing, energy-expending capacity, which is canonically cold-induced by ligand-dependent activation of β-adrenergic G protein-coupled receptors (GPCRs). Here, we uncover an alternate paradigm of GPCR-mediated adipose thermogenesis through the constitutively active receptor, GPR3. We show that the N terminus of GPR3 confers intrinsic signaling activity, resulting in continuous Gs-coupling and cAMP production without an exogenous ligand. Thus, transcriptional induction of Gpr3 represents the regulatory parallel to ligand-binding of conventional GPCRs. Consequently, increasing Gpr3 expression in thermogenic adipocytes is alone sufficient to drive energy expenditure and counteract metabolic disease in mice. Gpr3 transcription is cold-stimulated by a lipolytic signal, and dietary fat potentiates GPR3-dependent thermogenesis to amplify the response to caloric excess. Moreover, we find GPR3 to be an essential, adrenergic-independent regulator of human brown adipocytes. Taken together, our findings reveal a noncanonical mechanism of GPCR control and thermogenic activation through the lipolysis-induced expression of constitutively active GPR3.
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Affiliation(s)
- Olivia Sveidahl Johansen
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark; Embark Biotech ApS, Copenhagen, Denmark; Center for Adipocyte Signaling, University of Southern Denmark, Odense, Denmark
| | - Tao Ma
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark; Embark Biotech ApS, Copenhagen, Denmark
| | - Jakob Bondo Hansen
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark; Embark Biotech ApS, Copenhagen, Denmark
| | - Lasse Kruse Markussen
- Center for Adipocyte Signaling, University of Southern Denmark, Odense, Denmark; Functional Genomics and Metabolism Research Unit, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Renate Schreiber
- Institute of Molecular Biosciences, University of Graz, Graz, Austria
| | - Laia Reverte-Salisa
- Institute of Pharmacology and Toxicology, University Hospital, University of Bonn, Bonn, Germany
| | - Hua Dong
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | | | - Wenfei Sun
- Institute of Food, Nutrition and Health, ETH Zurich, Zurich, Switzerland
| | - Thorsten Gnad
- Institute of Pharmacology and Toxicology, University Hospital, University of Bonn, Bonn, Germany
| | - Iuliia Karavaeva
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Thomas Svava Nielsen
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Sander Kooijman
- Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Leiden, the Netherlands; Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | - Cheryl Cero
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Oksana Dmytriyeva
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Yachen Shen
- Institute for Diabetes, Obesity, and Metabolism, Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Maria Razzoli
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Shannon L O'Brien
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, Birmingham, UK; Institute of Pharmacology and Toxicology and Bio-Imaging Center, University of Würzburg, Würzburg, Germany
| | - Eline N Kuipers
- Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Leiden, the Netherlands; Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | - Carsten Haagen Nielsen
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Clinical Physiology, Nuclear Medicine & PET and Cluster for Molecular Imaging, Rigshospitalet, Copenhagen, Denmark
| | | | - Nienke Willemsen
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Naja Zenius Jespersen
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark; Centre of Inflammation and Metabolism and Centre for Physical Activity Research, Rigshospitalet, University Hospital of Copenhagen, Copenhagen, Denmark
| | - Morten Lundh
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Elahu Gosney Sustarsic
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Cecilie Mørch Hallgren
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Mikkel Frost
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Seth McGonigle
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Marie Sophie Isidor
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Christa Broholm
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Oluf Pedersen
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Jacob Bo Hansen
- Section for Cell Biology and Physiology, Department of Biology, University of Copenhagen, Copenhagen, Denmark
| | - Niels Grarup
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Torben Hansen
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Andreas Kjær
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark; Department of Clinical Physiology, Nuclear Medicine & PET and Cluster for Molecular Imaging, Rigshospitalet, Copenhagen, Denmark
| | - James G Granneman
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA
| | - M Madan Babu
- MRC Laboratory of Molecular Biology, Cambridge, UK; Department of Structural Biology and Center for Data Driven Discovery, St. Jude Children's Research Hospital, Memphis, TN, USA
| | - Davide Calebiro
- Institute of Metabolism and Systems Research, University of Birmingham, Birmingham, UK; Centre of Membrane Proteins and Receptors (COMPARE), Universities of Birmingham and Nottingham, Birmingham, UK; Institute of Pharmacology and Toxicology and Bio-Imaging Center, University of Würzburg, Würzburg, Germany
| | - Søren Nielsen
- Centre of Inflammation and Metabolism and Centre for Physical Activity Research, Rigshospitalet, University Hospital of Copenhagen, Copenhagen, Denmark
| | - Mikael Rydén
- Department of Medicine (H7), Karolinska Institute, Karolinska University Hospital, Stockholm, Sweden
| | - Raymond Soccio
- Institute for Diabetes, Obesity, and Metabolism, Department of Medicine, Division of Endocrinology, Diabetes, and Metabolism, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA
| | - Patrick C N Rensen
- Department of Medicine, Division of Endocrinology, Leiden University Medical Center, Leiden, the Netherlands; Einthoven Laboratory for Experimental Vascular Medicine, Leiden University Medical Center, Leiden, the Netherlands
| | - Jonas Thue Treebak
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Thue Walter Schwartz
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark; Embark Biotech ApS, Copenhagen, Denmark
| | - Brice Emanuelli
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Alessandro Bartolomucci
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, USA
| | - Alexander Pfeifer
- Institute of Pharmacology and Toxicology, University Hospital, University of Bonn, Bonn, Germany
| | - Rudolf Zechner
- Institute of Molecular Biosciences, University of Graz, Graz, Austria; BioTechMed-Graz, Graz, Austria
| | - Camilla Scheele
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark
| | - Susanne Mandrup
- Center for Adipocyte Signaling, University of Southern Denmark, Odense, Denmark; Functional Genomics and Metabolism Research Unit, Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Zachary Gerhart-Hines
- Novo Nordisk Foundation Center for Basic Metabolic Research, University of Copenhagen, Copenhagen, Denmark; Embark Biotech ApS, Copenhagen, Denmark; Center for Adipocyte Signaling, University of Southern Denmark, Odense, Denmark.
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12
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Keenan SN, De Nardo W, Lou J, Schittenhelm RB, Montgomery MK, Granneman JG, Hinde E, Watt MJ. Perilipin 5 S155 phosphorylation by PKA is required for the control of hepatic lipid metabolism and glycemic control. J Lipid Res 2021; 62:100016. [PMID: 33334871 PMCID: PMC7900760 DOI: 10.1194/jlr.ra120001126] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Revised: 12/09/2020] [Accepted: 12/17/2020] [Indexed: 12/22/2022] Open
Abstract
Perilipin 5 (PLIN5) is a lipid-droplet-associated protein that coordinates intracellular lipolysis in highly oxidative tissues and is thought to regulate lipid metabolism in response to phosphorylation by protein kinase A (PKA). We sought to identify PKA phosphorylation sites in PLIN5 and assess their functional relevance in cultured cells and the livers of mice. We detected phosphorylation on S155 and identified S155 as a functionally important site for lipid metabolism. Expression of phosphorylation-defective PLIN5 S155A in Plin5 null cells resulted in decreased rates of lipolysis and triglyceride-derived fatty acid oxidation. FLIM-FRET analysis of protein-protein interactions showed that PLIN5 S155 phosphorylation regulates PLIN5 interaction with adipose triglyceride lipase at the lipid droplet, but not with α-β hydrolase domain-containing 5. Re-expression of PLIN5 S155A in the liver of Plin5 liver-specific null mice reduced lipolysis compared with wild-type PLIN5 re-expression, but was not associated with other changes in hepatic lipid metabolism. Furthermore, glycemic control was impaired in mice with expression of PLIN5 S155A compared with mice expressing PLIN5. Together, these studies demonstrate that PLIN5 S155 is required for PKA-mediated lipolysis and builds on the body of evidence demonstrating a critical role for PLIN5 in coordinating lipid and glucose metabolism.
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Affiliation(s)
- Stacey N Keenan
- Department of Physiology, University of Melbourne, Melbourne, Victoria, Australia
| | - William De Nardo
- Department of Physiology, University of Melbourne, Melbourne, Victoria, Australia
| | - Jieqiong Lou
- School of Physics, University of Melbourne, Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Ralf B Schittenhelm
- Monash Proteomics & Metabolomics Facility and Department of Biochemistry and Molecular Biology, Monash University, Victoria, Australia
| | | | - James G Granneman
- Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI, USA
| | - Elizabeth Hinde
- School of Physics, University of Melbourne, Melbourne, Victoria, Australia; Department of Biochemistry and Molecular Biology, Bio21 Institute, University of Melbourne, Melbourne, Victoria, Australia
| | - Matthew J Watt
- Department of Physiology, University of Melbourne, Melbourne, Victoria, Australia.
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13
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Chen G, Zhou G, Lotvola A, Granneman JG, Wang J. ABHD5 suppresses cancer cell anabolism through lipolysis-dependent activation of the AMPK/mTORC1 pathway. J Biol Chem 2021; 296:100104. [PMID: 33219129 PMCID: PMC7949079 DOI: 10.1074/jbc.ra120.014682] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 11/11/2020] [Accepted: 11/20/2020] [Indexed: 12/15/2022] Open
Abstract
ABHD5 is an essential coactivator of ATGL, the rate-limiting triglyceride (TG) lipase in many cell types. Importantly, ABHD5 also functions as a tumor suppressor, and ABHD5 mRNA expression levels correlate with patient survival for several cancers. Nevertheless, the mechanisms involved in ABHD5-dependent tumor suppression are not known. We found that overexpression of ABHD5 induces cell cycle arrest at the G1 phase and causes growth retardation in a panel of prostate cancer cells. Transcriptomic profiling and biochemical analysis revealed that genetic or pharmacological activation of lipolysis by ABHD5 potently inhibits mTORC1 signaling, leading to a significant downregulation of protein synthesis. Mechanistically, we found that ABHD5 elevates intracellular AMP content, which activates AMPK, leading to inhibition of mTORC1. Interestingly, ABHD5-dependent suppression of mTORC1 was abrogated by pharmacological inhibition of DGAT1 or DGAT2, isoenzymes that re-esterify fatty acids in a process that consumes ATP. Collectively, this study maps out a novel molecular pathway crucial for limiting cancer cell proliferation, in which ABHD5-mediated lipolysis creates an energy-consuming futile cycle between TG hydrolysis and resynthesis, leading to inhibition of mTORC1 and cancer cell growth arrest.
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Affiliation(s)
- Guohua Chen
- Department of Pathology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Guoli Zhou
- Biomedical Research Informatics Core, Clinical and Translational Sciences Institute, Michigan State University, East Lansing, Michigan, USA
| | - Aaron Lotvola
- Department of Oncology, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - James G Granneman
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, Michigan, USA
| | - Jian Wang
- Department of Pathology, Wayne State University School of Medicine, Detroit, Michigan, USA.
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14
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Yu G, Yang Z, Peng T, Lv Y. Circular RNAs: Rising stars in lipid metabolism and lipid disorders. J Cell Physiol 2020; 236:4797-4806. [PMID: 33275299 DOI: 10.1002/jcp.30200] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 11/03/2020] [Accepted: 11/23/2020] [Indexed: 02/06/2023]
Abstract
The underlying mechanisms of circular RNAs (circRNAs) in lipid metabolism regulation and the pathogenesis of lipid disorder diseases are clarified in this review. circRNAs are produced from host genes by back splicing and are mainly degraded by RNase L. circRNAs act as molecular sponges or scaffolds that bind with microRNAs or proteins and thus affect the intracorporeal processes of lipid metabolism. CircRNA_11897 and circSAMD4A facilitated adipogenesis while circH19 and circRNA_26852 accelerated adipolysis in adipose tissue. CircSAMD4A promoted the differentiation of preadipocytes, but circH19 and circFUT10 inhibited this differentiation. CircFUT10 also promoted the proliferation of preadipocytes. CiRS-133 fostered the browning of white adipose tissue. CircACC1, circRNA_021412, circRNA_0046366, and circRNA_0046367 promoted the mitochondrial β-oxidation of fatty acids in hepatocytes. CircRNA_021412 suppressed the synthesis of triglycerides in hepatocytes. CircScd1 inhibited hepatic lipid droplet formation. circ_0092317, circ_0003546, circ_0028198, circ_0092317, and circACC1 probably reduced cholesterol efflux from macrophages. circ_0037251 likely promoted lipid accumulation and inhibited lipophagy in macrophages. circRNAs participate in lipid metabolism regulation and affect the development of lipid disorder diseases.
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Affiliation(s)
- Guangli Yu
- Clinical Anatomy & Reproductive Medicine Application Institute, Hengyang Medical College, University of South China, Hengyang, Hunan, China
| | - Zhou Yang
- Clinical Anatomy & Reproductive Medicine Application Institute, Hengyang Medical College, University of South China, Hengyang, Hunan, China
| | - Tianhong Peng
- Clinical Anatomy & Reproductive Medicine Application Institute, Hengyang Medical College, University of South China, Hengyang, Hunan, China
| | - Yuncheng Lv
- Clinical Anatomy & Reproductive Medicine Application Institute, Hengyang Medical College, University of South China, Hengyang, Hunan, China.,Institute of Basic Medical Sciences & Guangxi Key Laboratory of Diabetic Systems Medicine, Guilin Medical University, Guilin, Guangxi, China
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15
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Adipocyte lipolysis: from molecular mechanisms of regulation to disease and therapeutics. Biochem J 2020; 477:985-1008. [PMID: 32168372 DOI: 10.1042/bcj20190468] [Citation(s) in RCA: 114] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 02/19/2020] [Accepted: 02/26/2020] [Indexed: 12/20/2022]
Abstract
Fatty acids (FAs) are stored safely in the form of triacylglycerol (TAG) in lipid droplet (LD) organelles by professional storage cells called adipocytes. These lipids are mobilized during adipocyte lipolysis, the fundamental process of hydrolyzing TAG to FAs for internal or systemic energy use. Our understanding of adipocyte lipolysis has greatly increased over the past 50 years from a basic enzymatic process to a dynamic regulatory one, involving the assembly and disassembly of protein complexes on the surface of LDs. These dynamic interactions are regulated by hormonal signals such as catecholamines and insulin which have opposing effects on lipolysis. Upon stimulation, patatin-like phospholipase domain containing 2 (PNPLA2)/adipocyte triglyceride lipase (ATGL), the rate limiting enzyme for TAG hydrolysis, is activated by the interaction with its co-activator, alpha/beta hydrolase domain-containing protein 5 (ABHD5), which is normally bound to perilipin 1 (PLIN1). Recently identified negative regulators of lipolysis include G0/G1 switch gene 2 (G0S2) and PNPLA3 which interact with PNPLA2 and ABHD5, respectively. This review focuses on the dynamic protein-protein interactions involved in lipolysis and discusses some of the emerging concepts in the control of lipolysis that include allosteric regulation and protein turnover. Furthermore, recent research demonstrates that many of the proteins involved in adipocyte lipolysis are multifunctional enzymes and that lipolysis can mediate homeostatic metabolic signals at both the cellular and whole-body level to promote inter-organ communication. Finally, adipocyte lipolysis is involved in various diseases such as cancer, type 2 diabetes and fatty liver disease, and targeting adipocyte lipolysis is of therapeutic interest.
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16
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Lyons C, Razzoli M, Larson E, Svedberg D, Frontini A, Cinti S, Vulchanova L, Sanders M, Thomas M, Bartolomucci A. Optogenetic-induced sympathetic neuromodulation of brown adipose tissue thermogenesis. FASEB J 2020; 34:2765-2773. [PMID: 31908033 PMCID: PMC7306786 DOI: 10.1096/fj.201901361rr] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Revised: 12/09/2019] [Accepted: 12/09/2019] [Indexed: 11/11/2022]
Abstract
The brown adipose tissue (BAT) is a thermogenic organ that plays a major role in energy balance, obesity, and diabetes due to the potent glucose and lipid clearance that fuels its thermogenesis, which is largely mediated via sympathetic nervous system activation. However, thus far there has been little experimental validation of the hypothesis that selective neuromodulation of the sympathetic nerves innervating the BAT is sufficient to elicit thermogenesis in mice. We generated mice expressing blue light-activated channelrhodopsin-2 (ChR2) in the sympathetic nerves innervating the BAT using two different strategies: injecting the BAT of C57Bl/6J mice with AAV6-hSyn-ChR2 (H134R)-EYFP; crossbreeding tyrosine hydroxylase-Cre mice with floxed-stop ChR2-EYFP mice. The nerves in the BAT expressing ChR2 were selectively stimulated with a blue LED light positioned underneath the fat pad of anesthetized mice, while the BAT and core temperatures were simultaneously recorded. Using immunohistochemistry we confirmed the selective expression of EYFP in TH positive nerves fibers. In addition, local optogenetic stimulation of the sympathetic nerves induced significant increase in the BAT temperature followed by an increase in core temperature in mice expressing ChR2, but not in the respective controls. The BAT activation was also paralleled by increased levels of pre-UCP1 transcript. Our results demonstrate that local optogenetic stimulation of the sympathetic nerves is sufficient to elicit BAT and core thermogenesis, thus suggesting that peripheral neuromodulation has the potential to be exploited as an alternative to pharmacotherapies to elicit organ activation and thus ameliorate type 2 diabetes and/or obesity.
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Affiliation(s)
- Carey Lyons
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, 55455
- Graduate Program in Neuroscience, University of Minnesota, Minneapolis, MN, 55455
| | - Maria Razzoli
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, 55455
| | - Erin Larson
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, 55455
| | - Daniel Svedberg
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, 55455
| | - Andrea Frontini
- Department of Public Health, Experimental and Forensic Medicine, University of Pavia, 27100, Pavia, Italy
| | - Saverio Cinti
- Università Politecnica delle Marche, 60020 Ancona, Italy
| | - Lucy Vulchanova
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, 55455
| | - Mark Sanders
- University Imaging Center, University of Minnesota, Minneapolis, MN, 55455
| | - Mark Thomas
- Department of Neuroscience, University of Minnesota, Minneapolis, MN, 55455
| | - Alessandro Bartolomucci
- Department of Integrative Biology and Physiology, University of Minnesota, Minneapolis, MN, 55455
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17
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Mottillo EP, Zhang H, Yang A, Zhou L, Granneman JG. Genetically-encoded sensors to detect fatty acid production and trafficking. Mol Metab 2019; 29:55-64. [PMID: 31668392 PMCID: PMC6726923 DOI: 10.1016/j.molmet.2019.08.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 08/09/2019] [Accepted: 08/14/2019] [Indexed: 02/09/2023] Open
Abstract
OBJECTIVE Fatty acids are important for biological function; however, in excess, they can cause metabolic dysregulation. Methods to image and detect fatty acids in real time are lacking. Therefore, the current study examined the dynamics of fatty acid trafficking and signaling utilizing novel fluorescent and luminescent approaches. METHODS We generated fluorescent and luminescent-based genetically-encoded sensors based upon the ligand-dependent interaction between PPARα and SRC-1 to image and detect cellular dynamics of fatty acid trafficking. RESULTS The use of a fluorescent sensor demonstrates that fatty acids traffic rapidly from lipid droplets to the nucleus. Both major lipases ATGL and HSL contribute to fatty acid signaling from lipid droplet to nucleus, however, their dynamics differ. Furthermore, direct activation of lipolysis, independent of receptor-mediated signaling is sufficient to promote lipid droplet to nuclear trafficking of fatty acids. A luminescent-based sensor that reports intracellular fatty acid levels is amenable to high-throughput analysis. CONCLUSIONS Fatty acids traffic from lipid droplets to the nucleus within minutes of stimulated lipolysis. Genetically-encoded fluorescent and luminescent based sensors can be used to probe the dynamics of fatty acid trafficking and signaling.
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Affiliation(s)
- Emilio P Mottillo
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, 48201, USA.
| | - Huamei Zhang
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Alexander Yang
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - Li Zhou
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, 48201, USA
| | - James G Granneman
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, 48201, USA
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18
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Goldberg IJ, Reue K, Abumrad NA, Bickel PE, Cohen S, Fisher EA, Galis ZS, Granneman JG, Lewandowski ED, Murphy R, Olive M, Schaffer JE, Schwartz-Longacre L, Shulman GI, Walther TC, Chen J. Deciphering the Role of Lipid Droplets in Cardiovascular Disease: A Report From the 2017 National Heart, Lung, and Blood Institute Workshop. Circulation 2019; 138:305-315. [PMID: 30012703 DOI: 10.1161/circulationaha.118.033704] [Citation(s) in RCA: 76] [Impact Index Per Article: 15.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Lipid droplets (LDs) are distinct and dynamic organelles that affect the health of cells and organs. Much progress has been made in understanding how these structures are formed, how they interact with other cellular organelles, how they are used for storage of triacylglycerol in adipose tissue, and how they regulate lipolysis. Our understanding of the biology of LDs in the heart and vascular tissue is relatively primitive in comparison with LDs in adipose tissue and liver. The National Heart, Lung, and Blood Institute convened a working group to discuss how LDs affect cardiovascular diseases. The goal of the working group was to examine the current state of knowledge on the cell biology of LDs, including current methods to study them in cells and organs and reflect on how LDs influence the development and progression of cardiovascular diseases. This review summarizes the working group discussion and recommendations on research areas ripe for future investigation that will likely improve our understanding of atherosclerosis and heart function.
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Affiliation(s)
| | - Karen Reue
- University of California, Los Angeles (K.R.)
| | | | - Perry E Bickel
- University of Texas Southwestern Medical Center, Dallas (P.E.B.)
| | - Sarah Cohen
- University of North Carolina at Chapel Hill (S.C.)
| | | | - Zorina S Galis
- National Institutes of Health/National, Heart, Lung, and Blood Institute, Bethesda, MD (Z.S.G., M.O., L.S.-L., J.C.)
| | | | | | | | - Michelle Olive
- National Institutes of Health/National, Heart, Lung, and Blood Institute, Bethesda, MD (Z.S.G., M.O., L.S.-L., J.C.)
| | | | - Lisa Schwartz-Longacre
- National Institutes of Health/National, Heart, Lung, and Blood Institute, Bethesda, MD (Z.S.G., M.O., L.S.-L., J.C.)
| | - Gerald I Shulman
- Yale University, Howard Hughes Medical Institute, New Haven, CT (G.I.S.)
| | - Tobias C Walther
- Harvard University, Howard Hughes Medical Institute, Boston, MA (T.C.W.)
| | - Jue Chen
- National Institutes of Health/National, Heart, Lung, and Blood Institute, Bethesda, MD (Z.S.G., M.O., L.S.-L., J.C.).
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19
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Wang Y, Kory N, BasuRay S, Cohen JC, Hobbs HH. PNPLA3, CGI-58, and Inhibition of Hepatic Triglyceride Hydrolysis in Mice. Hepatology 2019; 69:2427-2441. [PMID: 30802989 PMCID: PMC6563103 DOI: 10.1002/hep.30583] [Citation(s) in RCA: 100] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Accepted: 02/16/2019] [Indexed: 12/12/2022]
Abstract
A variant (148M) in patatin-like phospholipase domain-containing protein 3 (PNPLA3) is a major risk factor for fatty liver disease. Despite its clinical importance, the pathogenic mechanism linking the variant to liver disease remains poorly defined. Previously, we showed that PNPLA3(148M) accumulates to high levels on hepatic lipid droplets (LDs). Here we examined the effect of that accumulation on triglyceride (TG) hydrolysis by adipose triglyceride lipase (ATGL), the major lipase in the liver. As expected, overexpression of ATGL in cultured hepatoma (HuH-7) cells depleted the cells of LDs, but unexpectedly, co-expression of PNPLA3(wild type [WT] or 148M) with ATGL inhibited that depletion. The inhibitory effect of PNPLA3 was not caused by the displacement of ATGL from LDs. We tested the hypothesis that PNPLA3 interferes with ATGL activity by interacting with its cofactor, comparative gene identification-58 (CGI-58). Evidence supporting such an interaction came from two findings. First, co-expression of PNPLA3 and CGI-58 resulted in LD depletion in cultured cells, but expression of PNPLA3 alone did not. Second, PNPLA3 failed to localize to hepatic LDs in liver-specific Cgi-58 knockout (KO) mice. Moreover, overexpression of PNPLA3(148M) increased hepatic TG levels in WT, but not in Cgi-58 KO mice. Thus, the pro-steatotic effects of PNPLA3 required the presence of CGI-58. Co-immunoprecipitation and pulldown experiments in livers of mice and in vitro using purified proteins provided evidence that PNPLA3 and CGI-58 can interact directly. Conclusion: Taken together, these findings are consistent with a model in which PNPLA3(148M) promotes steatosis by CGI-58-dependent inhibition of ATGL on LDs.
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Affiliation(s)
- Yang Wang
- Department of Molecular GeneticsUniversity of Texas Southwestern Medical CenterDallasTX
| | - Nora Kory
- Department of Molecular GeneticsUniversity of Texas Southwestern Medical CenterDallasTX
| | - Soumik BasuRay
- Department of Molecular GeneticsUniversity of Texas Southwestern Medical CenterDallasTX
| | - Jonathan C. Cohen
- Department of Internal MedicineUniversity of Texas Southwestern Medical CenterDallasTX,The Center for Human NutritionUniversity of Texas Southwestern Medical CenterDallas TX
| | - Helen H. Hobbs
- Department of Molecular GeneticsUniversity of Texas Southwestern Medical CenterDallasTX,Department of Internal MedicineUniversity of Texas Southwestern Medical CenterDallasTX,Howard Hughes Medical InstituteUniversity of Texas Southwestern Medical CenterDallasTX
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20
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Yang A, Mottillo EP, Mladenovic-Lucas L, Zhou L, Granneman JG. Dynamic interactions of ABHD5 with PNPLA3 regulate triacylglycerol metabolism in brown adipocytes. Nat Metab 2019; 1:560-569. [PMID: 31497752 PMCID: PMC6730670 DOI: 10.1038/s42255-019-0066-3] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Patatin-Like Phospholipase Domain Containing 2 (PNPLA2)/Adipose Triglyceride Lipase (ATGL) and PNPLA3/Adiponutrin are close paralogs that appear to have opposite functions on triacylglycerol (TAG) mobilization and storage. PNPLA2/ATGL is a major triglyceride lipase in adipose tissue and liver, whereas a common human variant of PNPLA3, I148M, greatly increases risk of hepatosteatosis. Nonetheless, the function of PNPLA3 and the mechanism by which the I148M variant promotes TAG accumulation are poorly understood. Here we demonstrate that PNPLA3 strongly interacts with α/β hydrolase domain-containing 5 (ABHD5/CGI-58), an essential co-activator of PNPLA2/ATGL. Molecular imaging experiments demonstrate that PNPLA3 effectively competes with PNPLA2/ATGL for ABHD5, and that PNPLA3 I148M is more effective in this regard. Inducible overexpression of PNPLA3 I148M greatly suppressed PNPLA2/ATGL-dependent lipolysis and triggered massive TAG accumulation in brown adipocytes, and these effects were dependent on ABHD5. The interaction of PNPLA3 and ABHD5 can be regulated by fatty acid supplementation and synthetic ABHD5 ligands, raising the possibility that this interaction might be targeted for treatment of fatty liver disease.
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Affiliation(s)
- Alexander Yang
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA 48201
- Co-first authors
| | - Emilio P. Mottillo
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA 48201
- Co-first authors
- Correspondence and requests for materials should be addressed to E.P.M. or J.G.G. (J.G.G.), (E.P.M.)
| | - Ljiljana Mladenovic-Lucas
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA 48201
| | - Li Zhou
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA 48201
| | - James G. Granneman
- Center for Molecular Medicine and Genetics, Wayne State University School of Medicine, Detroit, MI, USA 48201
- Correspondence and requests for materials should be addressed to E.P.M. or J.G.G. (J.G.G.), (E.P.M.)
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21
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Quiroga AD, Lehner R. Pharmacological intervention of liver triacylglycerol lipolysis: The good, the bad and the ugly. Biochem Pharmacol 2018; 155:233-241. [PMID: 30006193 DOI: 10.1016/j.bcp.2018.07.005] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Accepted: 07/09/2018] [Indexed: 02/07/2023]
Abstract
Excessive triacylglycerol (TG) accumulation is the distinctive feature of obesity. In the liver, sustained TG accretion leads to nonalcoholic fatty liver disease (NAFLD), eventually progressing to non-alcoholic steatohepatitis (NASH) and cirrhosis, which is associated with complications including hepatic failure, hepatocellular carcinoma and death. Pharmacological interventions are actively pursued to prevent lipid accumulation in hepatocytes and, therefore, to ameliorate the associated pathophysiological conditions. Here, we sought to provide an overview of the pharmacological approaches to up- or downregulate the expression and activities of the enzymes involved in hepatic TG hydrolysis. Fatty acids (FA) released by hydrolysis of hepatic TG can be used for β-oxidation, signaling, and for very low-density lipoprotein (VLDL)-TG synthesis. Originally, lipolysis was believed to be centered in the adipose and to be catalyzed by only two lipases, hormone-sensitive lipase (HSL) and monoacylglycerol lipase (MAGL). However, genetic ablation of HSL expression in mice failed to erase TG hydrolysis in adipocytes leading to the identification of a third lipase termed adipose triglyceride lipase (ATGL). Although these three enzymes are considered to be the main players governing lipolysis in the adipocyte, other lipolytic enzymes have been described to contribute to hepatic TG metabolism. These include adiponutrin/patatin-like phospholipase domain containing 3 (PNPLA3), some members of the carboxylesterase family (CES/Ces), arylacetamide deacetylase (AADAC), lysosomal acid lipase (LAL) and hepatic lipase (HL). This review highlights the consequences of pharmacological interventions of liver lipases that degrade TG in cytosolic lipid droplets, in the endoplasmic reticulum, in the late endosomes/lysosomes and along the secretory route.
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Affiliation(s)
- Ariel D Quiroga
- Instituto de Fisiología Experimental (IFISE), Área Morfología, Facultad de Ciencias Bioquímicas y Farmacéuticas, CONICET, UNR, Rosario, Argentina.
| | - Richard Lehner
- Group on Molecular and Cell Biology of Lipids, Department of Pediatrics, Department of Cell Biology, University of Alberta, Edmonton, Alberta, Canada.
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