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Shinde AB, Nunn ER, Wilson GA, Chvasta MT, Pinette JA, Myers JW, Peck SH, Spinelli JB, Zaganjor E. Inhibition of nucleotide biosynthesis disrupts lipid accumulation and adipogenesis. J Biol Chem 2023; 299:104635. [PMID: 36963490 PMCID: PMC10149209 DOI: 10.1016/j.jbc.2023.104635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Revised: 02/21/2023] [Accepted: 03/13/2023] [Indexed: 03/26/2023] Open
Abstract
Energy balance and nutrient availability are key determinants of cellular decisions to remain quiescent, proliferate or differentiate into a mature cell. After assessing its environmental state, the cell must rewire its metabolism to support distinct cellular outcomes. Mechanistically, how metabolites regulate cell fate decisions is poorly understood. We used adipogenesis as our model system to ascertain the role of metabolism in differentiation. We isolated adipose tissue stromal vascular fraction (SVF) cells and profiled metabolites before and after adipogenic differentiation to identify metabolic signatures associated with these distinct cellular states. We found that differentiation alters nucleotide accumulation. Furthermore, inhibition of nucleotide biosynthesis prevented lipid storage within adipocytes and downregulated the expression of lipogenic factors. In contrast to proliferating cells, in which mTORC1 is activated by purine accumulation, mTORC1 signaling was unaffected by purine levels in differentiating adipocytes. Rather, our data indicated that purines regulate transcriptional activators of adipogenesis, PPARγ and C/EBPα to promote differentiation. Although de novo nucleotide biosynthesis has mainly been studied in proliferation, our study points to its requirement in adipocyte differentiation.
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Affiliation(s)
- Abhijit B Shinde
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Elizabeth R Nunn
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Genesis A Wilson
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Mathew T Chvasta
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Julia A Pinette
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Jacob W Myers
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA
| | - Sun H Peck
- Department of Medicine, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA; Nashville Veterans Affairs Medical Center, Department of Veterans Affairs, Nashville, TN, USA
| | - Jessica B Spinelli
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Elma Zaganjor
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, USA; Vanderbilt Digestive Disease Research Center, Vanderbilt University Medical Center, Nashville, TN, USA; Vanderbilt Diabetes Research Center, Vanderbilt University, Nashville, TN, USA.
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Caslin HL, Abebayehu D, Pinette JA, Ryan JJ. Lactate Is a Metabolic Mediator That Shapes Immune Cell Fate and Function. Front Physiol 2021; 12:688485. [PMID: 34733170 PMCID: PMC8558259 DOI: 10.3389/fphys.2021.688485] [Citation(s) in RCA: 44] [Impact Index Per Article: 14.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Accepted: 09/22/2021] [Indexed: 12/12/2022] Open
Abstract
Lactate and the associated H+ ions are still introduced in many biochemistry and general biology textbooks and courses as a metabolic by-product within fast or oxygen-independent glycolysis. However, the role of lactate as a fuel source has been well-appreciated in the field of physiology, and the role of lactate as a metabolic feedback regulator and distinct signaling molecule is beginning to gain traction in the field of immunology. We now know that while lactate and the associated H+ ions are generally immunosuppressive negative regulators, there are cell, receptor, mediator, and microenvironment-specific effects that augment T helper (Th)17, macrophage (M)2, tumor-associated macrophage, and neutrophil functions. Moreover, we are beginning to uncover how lactate and H+ utilize different transporters and signaling cascades in various immune cell types. These immunomodulatory effects may have a substantial impact in cancer, sepsis, autoimmunity, wound healing, and other immunomodulatory conditions with elevated lactate levels. In this article, we summarize the known effects of lactate and H+ on immune cells to hypothesize potential explanations for the divergent inflammatory vs. anti-inflammatory effects.
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Affiliation(s)
- Heather L Caslin
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, United States.,Department of Biology, Virginia Commonwealth University, Richmond, VA, United States
| | - Daniel Abebayehu
- Department of Biology, Virginia Commonwealth University, Richmond, VA, United States.,Department of Biomedical Engineering, University of Virginia, Charlottesville, VA, United States
| | - Julia A Pinette
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, United States
| | - John J Ryan
- Department of Biology, Virginia Commonwealth University, Richmond, VA, United States
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Chinowsky CR, Pinette JA, Meenderink LM, Lau KS, Tyska MJ. Nonmuscle myosin-2 contractility-dependent actin turnover limits the length of epithelial microvilli. Mol Biol Cell 2020; 31:2803-2815. [PMID: 33026933 PMCID: PMC7851865 DOI: 10.1091/mbc.e20-09-0582] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2020] [Revised: 09/24/2020] [Accepted: 09/28/2020] [Indexed: 12/14/2022] Open
Abstract
Brush border microvilli enable functions that are critical for epithelial homeostasis, including solute uptake and host defense. However, the mechanisms that regulate the assembly and morphology of these protrusions are poorly understood. The parallel actin bundles that support microvilli have their pointed-end rootlets anchored in a filamentous meshwork referred to as the "terminal web." Although classic electron microscopy studies revealed complex ultrastructure, the composition and function of the terminal web remain unclear. Here we identify nonmuscle myosin-2C (NM2C) as a component of the terminal web. NM2C is found in a dense, isotropic layer of puncta across the subapical domain, which transects the rootlets of microvillar actin bundles. Puncta are separated by ∼210 nm, the expected size of filaments formed by NM2C. In intestinal organoid cultures, the terminal web NM2C network is highly dynamic and exhibits continuous remodeling. Using pharmacological and genetic perturbations in cultured intestinal epithelial cells, we found that NM2C controls the length of growing microvilli by regulating actin turnover in a manner that requires a fully active motor domain. Our findings answer a decades-old question on the function of terminal web myosin and hold broad implications for understanding apical morphogenesis in diverse epithelial systems.
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Affiliation(s)
- Colbie R. Chinowsky
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Julia A. Pinette
- Department of Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Leslie M. Meenderink
- Division of Infectious Diseases, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN 37232
| | - Ken S. Lau
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Matthew J. Tyska
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
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Pinette JA, Mao S, Millis BA, Krystofiak ES, Faust JJ, Tyska MJ. Brush border protocadherin CDHR2 promotes the elongation and maximized packing of microvilli in vivo. Mol Biol Cell 2018; 30:108-118. [PMID: 30403560 PMCID: PMC6337912 DOI: 10.1091/mbc.e18-09-0558] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Transporting epithelial cells optimize their morphology for solute uptake by building an apical specialization: a dense array of microvilli that serves to increase membrane surface area. In the intestinal tract, individual cells build thousands of microvilli, which pack tightly to form the brush border. Recent studies implicate adhesion molecule CDHR2 in the regulation of microvillar packing via the formation of adhesion complexes between the tips of adjacent protrusions. To gain insight on how CDHR2 contributes to brush border morphogenesis and enterocyte function under native in vivo conditions, we generated mice lacking CDHR2 expression in the intestinal tract. Although CDHR2 knockout (KO) mice are viable, body weight trends lower and careful examination of tissue, cell, and brush border morphology revealed several perturbations that likely contribute to reduced functional capacity of KO intestine. In the absence of CDHR2, microvilli are significantly shorter, and exhibit disordered packing and a 30% decrease in packing density. These structural perturbations are linked to decreased levels of key solute processing and transporting factors in the brush border. Thus, CDHR2 functions to elongate microvilli and maximize their numbers on the apical surface, which together serve to increase the functional capacity of enterocyte.
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Affiliation(s)
- Julia A Pinette
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Suli Mao
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Bryan A Millis
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Evan S Krystofiak
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - James J Faust
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
| | - Matthew J Tyska
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232
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