1
|
Castillo HB, Shuster SO, Tarekegn LH, Davis CM. Oleic acid differentially affects lipid droplet storage of de novo synthesized lipids in hepatocytes and adipocytes. Chem Commun (Camb) 2024; 60:3138-3141. [PMID: 38329230 PMCID: PMC10939124 DOI: 10.1039/d3cc04829b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 01/29/2024] [Indexed: 02/09/2024]
Abstract
Lipogenesis is a vital but often dysregulated metabolic pathway. Here we use optical photothermal infrared imaging to quantify lipogenesis rates of isotopically labelled oleic acid and glucose concomitantly in live cells. In hepatocytes, but not adipocytes, we find that oleic acid feeding at 60 μM increases the number and size of lipid droplets (LDs) while simultaneously inhibiting storage of de novo synthesized lipids in LDs. Our results demonstrate alternate regulation of lipogenesis between cell types.
Collapse
Affiliation(s)
- Hannah B Castillo
- Department of Chemistry, Yale University, New Haven, Connecticut, 06511, USA.
| | - Sydney O Shuster
- Department of Chemistry, Yale University, New Haven, Connecticut, 06511, USA.
| | - Lydia H Tarekegn
- Department of Chemistry, Yale University, New Haven, Connecticut, 06511, USA.
| | - Caitlin M Davis
- Department of Chemistry, Yale University, New Haven, Connecticut, 06511, USA.
| |
Collapse
|
2
|
Sivadas A, McDonald EF, Shuster SO, Davis CM, Plate L. Site-specific crosslinking reveals Phosphofructokinase-L inhibition drives self-assembly and attenuation of protein interactions. Adv Biol Regul 2023; 90:100987. [PMID: 37806136 DOI: 10.1016/j.jbior.2023.100987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Accepted: 09/25/2023] [Indexed: 10/10/2023]
Abstract
Phosphofructokinase is the central enzyme in glycolysis and constitutes a highly regulated step. The liver isoform (PFKL) compartmentalizes during activation and inhibition in vitro and in vivo, respectively. Compartmentalized PFKL is hypothesized to modulate metabolic flux consistent with its central role as the rate limiting step in glycolysis. PFKL tetramers self-assemble at two interfaces in the monomer (interface 1 and 2), yet how these interfaces contribute to PFKL compartmentalization and drive protein interactions remains unclear. Here, we used site-specific incorporation of noncanonical photocrosslinking amino acids to identify PFKL interactors at interface 1, 2, and the active site. Tandem mass tag-based quantitative interactomics reveals interface 2 as a hotspot for PFKL interactions, particularly with cytoskeletal, glycolytic, and carbohydrate derivative metabolic proteins. Furthermore, PFKL compartmentalization into puncta was observed in human cells using citrate inhibition. Puncta formation attenuated crosslinked protein-protein interactions with the cytoskeleton at interface 2. This result suggests that PFKL compartmentalization sequesters interface 2, but not interface 1, and may modulate associated protein assemblies with the cytoskeleton.
Collapse
Affiliation(s)
- Athira Sivadas
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
| | - Eli Fritz McDonald
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA; Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | | | - Caitlin M Davis
- Department of Chemistry, Yale University, New Haven, CT, USA
| | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA; Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA; Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA.
| |
Collapse
|
3
|
Castillo HB, Shuster SO, Tarekegn LH, Davis CM. Oleic acid differentially affects de novo lipogenesis in adipocytes and hepatocytes. bioRxiv 2023:2023.10.04.560581. [PMID: 37873279 PMCID: PMC10592964 DOI: 10.1101/2023.10.04.560581] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
Lipogenesis is a vital but often dysregulated metabolic pathway. We report super-resolution multiplexed vibrational imaging of lipogenesis rates and pathways using isotopically labelled oleic acid and glucose as probes in live adipocytes and hepatocytes. These findings suggest oleic acid inhibits de novo lipogenesis (DNL), but not total lipogenesis, in hepatocytes. No significant effect is seen in adipocytes. These differential effects may be due to alternate regulation of DNL between cell types and could help explain the complicated role oleic acid plays in metabolism.
Collapse
Affiliation(s)
- Hannah B. Castillo
- Department of Chemistry, Yale University, New Haven, Connecticut, 06511, United States
| | - Sydney O. Shuster
- Department of Chemistry, Yale University, New Haven, Connecticut, 06511, United States
| | - Lydia H. Tarekegn
- Department of Chemistry, Yale University, New Haven, Connecticut, 06511, United States
| | - Caitlin M. Davis
- Department of Chemistry, Yale University, New Haven, Connecticut, 06511, United States
| |
Collapse
|
4
|
Sivadas A, McDonald EF, Shuster SO, Davis CM, Plate L. Site-Specific Crosslinking Reveals Phosphofructokinase-L Inhibition Drives Self-Assembly and Attenuation of Protein Interactions. bioRxiv 2023:2023.09.19.558525. [PMID: 37781627 PMCID: PMC10541129 DOI: 10.1101/2023.09.19.558525] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/03/2023]
Abstract
Phosphofructokinase is the central enzyme in glycolysis and constitutes a highly regulated step. The liver isoform (PFKL) compartmentalizes during activation and inhibition in vitro and in vivo respectively. Compartmentalized PFKL is hypothesized to modulate metabolic flux consistent with its central role as the rate limiting step in glycolysis. PFKL tetramers self-assemble at two interfaces in the monomer (interface 1 and 2), yet how these interfaces contribute to PFKL compartmentalization and drive protein interactions remains unclear. Here, we used site-specific incorporation of noncanonical photocrosslinking amino acids to identify PFKL interactors at interface 1, 2, and the active site. Tandem mass tag-based quantitative interactomics reveals interface 2 as a hotspot for PFKL interactions, particularly with cytoskeletal, glycolytic, and carbohydrate derivative metabolic proteins. Furthermore, PFKL compartmentalization into puncta was observed in human cells using citrate inhibition. Puncta formation attenuated crosslinked protein-protein interactions with the cytoskeleton at interface 2. This result suggests that PFKL compartmentalization sequesters interface 2, but not interface 1, and may modulate associated protein assemblies with the cytoskeleton.
Collapse
Affiliation(s)
- Athira Sivadas
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
| | - Eli Fritz McDonald
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
- Center for Structural Biology, Vanderbilt University, Nashville, TN, USA
| | | | | | - Lars Plate
- Department of Chemistry, Vanderbilt University, Nashville, TN, USA
- Department of Biological Sciences, Vanderbilt University, Nashville, TN, USA
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| |
Collapse
|
5
|
Abstract
De novo lipogenesis (DNL) is a critical metabolic process that provides the majority of lipids for adipocyte and liver tissue. In cancer, obesity, type II diabetes, and nonalcoholic fatty liver disease DNL becomes dysregulated. A deeper understanding of the rates and of subcellular organization of DNL is necessary for identifying how this dysregulation occurs and varies across individuals and diseases. However, DNL is difficult to study inside the cell because labeling lipids and their precursors is not trivial. Existing techniques either can only measure parts of DNL, like glucose uptake, or do not provide spatiotemporal resolution. Here, we track DNL in space and time as isotopically labeled glucose is converted to lipids in adipocytes using optical photothermal infrared microscopy (OPTIR). OPTIR provides submicron resolution infrared imaging of the glucose metabolism in both living and fixed cells while also reporting on the identity of lipids and other biomolecules. We show significant incorporation of the labeled carbons into triglycerides in lipid droplets over the course of 72 h. Live cells had better preservation of lipid droplet morphology, but both showed similar DNL rates. Rates of DNL, as measured by the ratio of 13C-labeled lipid to 12C-labeled lipid, were heterogeneous, with differences within and between lipid droplets and from cell to cell. The high rates of DNL measured in adipocyte cells match upregulated rates of DNL previously reported in PANC1 pancreatic cancer cells. Taken together, our findings support a model where DNL is locally regulated to meet energy needs within cells.
Collapse
Affiliation(s)
- Sydney O Shuster
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06511, United States
| | - Michael J Burke
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06511, United States
| | - Caitlin M Davis
- Department of Chemistry, Yale University, 225 Prospect Street, New Haven, Connecticut 06511, United States
| |
Collapse
|
6
|
Abstract
Liquid-liquid phase-separation (LLPS) is a biological phenomenon wherein a metastable, concentrated droplet phase of biomolecules spontaneously forms. A link may exist between LLPS of proteins and the disease-related process of amyloid fibril formation; however, this connection is not fully understood. Here, we investigated the relationship between LLPS and aggregation of the C-terminal domain of TAR DNA-binding protein 43, an amyotrophic lateral sclerosis-related protein known to both phase-separate and form amyloids, by monitoring conformational changes during droplet aging using Raman spectroscopy. We found that the earliest aggregation events occurred within droplets as indicated by the development of β-sheet structure and increased thioflavin-T emission. Interestingly, filamentous aggregates appeared outside the solidified droplets at a later time, suggestive that amyloid formation is a heterogeneous process under LLPS solution conditions. Furthermore, the secondary structure content of aggregated structures inside droplets are distinct from that in de novo fibrils, implying that fibril polymorphism develops as a result of different environments (LLPS vs. bulk solution), which may have pathological significance.
Collapse
Affiliation(s)
- Sydney O Shuster
- Laboratory of Protein Conformation and Dynamics, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Jennifer C Lee
- Laboratory of Protein Conformation and Dynamics, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland, USA.
| |
Collapse
|
7
|
Abstract
Aggregated TAR DNA-binding protein 43 (TDP-43) forms the cytoplasmic hallmarks associated with patients suffering from amyotrophic lateral sclerosis and frontotemporal lobar degeneration with ubiquitin. Under normal conditions, TDP-43 is a 414-amino acid protein; however, aggregates are enriched with N-terminal truncations which contain residues 267-414, known as the C-terminal domain of TDP-43 (TDP-43CTD). To gain residue-specific information on the aggregation process of TDP-43CTD, we created three single-Trp containing mutants (W385F/W412F, W334F/W412F, and W334F/W385F) by substituting two of the three native Trp residues with Phe, yielding fluorescent probes at W334, W385, and W412, respectively. Aggregation kinetics, secondary structure, and fibril morphology were compared to the wild-type protein using thioflavin-T fluorescence, Raman spectroscopy, and transmission electron microscopy, respectively. While only W334 is determined to be in the proteinase-K resistant core, all three sites are sensitive reporters of aggregation, revealing site-specific differences. Interestingly, W334 exhibited unusual multistep Trp kinetics, pinpointing a distinctive role for W334 and its nearby region during aggregation. This behavior is retained even upon seeding, suggesting the observed spectral change is related to fibril growth. This work provides new insights into the aggregation mechanism of TDP-43CTD and exemplifies the advantages of Trp as a site-specific environmentally sensitive fluorescent probe.
Collapse
Affiliation(s)
- Sydney O Shuster
- Laboratory of Protein Conformation and Dynamics, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Jennifer C Lee
- Laboratory of Protein Conformation and Dynamics, Biochemistry and Biophysics Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892, United States
| |
Collapse
|
8
|
Shuster SO, Fica-Contreras SM, Hedges JS, Henning NJ, Choi S. Comparison of the reaction of methylglyoxal (MGO) with murine and human amyloid beta (Aβ): Insights into a mechanism of Alzheimer's disease (AD). Biochem Biophys Res Commun 2020; 533:1298-1302. [PMID: 33046246 DOI: 10.1016/j.bbrc.2020.10.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [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: 09/23/2020] [Accepted: 10/04/2020] [Indexed: 01/19/2023]
Abstract
Reacted with methylglyoxal (MGO), murine Aβ(1-40) (mAβ) produced significantly less superoxide anion (O2•-) compared to human Aβ(1-40) (hAβ). The reactions of MGO with mAβ(R13H), hAβ(H13F), Nα-acetyl-l-lysine, and Nα-acetyl-l-arginine implied that the lack of His13 in mAβ prohibits its Lys16 residue from reacting to produce cross-linked reaction products and O2•-. Our results suggest that murine brains are under less oxidative stress than human brains, which may be one of the reasons why rodents do not develop AD-like symptoms, and which provides further insight into a chemical mechanism for the development of AD in humans.
Collapse
Affiliation(s)
- Sydney O Shuster
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, 05753, USA
| | | | - Jake S Hedges
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, 05753, USA
| | - Nathaniel J Henning
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, 05753, USA
| | - Sunhee Choi
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, 05753, USA.
| |
Collapse
|
9
|
Fica-Contreras SM, Shuster SO, Durfee ND, Bowe GJK, Henning NJ, Hill SA, Vrla GD, Stillman DR, Suralik KM, Sandwick RK, Choi S. Glycation of Lys-16 and Arg-5 in amyloid-β and the presence of Cu 2+ play a major role in the oxidative stress mechanism of Alzheimer's disease. J Biol Inorg Chem 2017; 22:1211-1222. [PMID: 29038915 DOI: 10.1007/s00775-017-1497-5] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2017] [Accepted: 10/09/2017] [Indexed: 01/21/2023]
Abstract
Extensive research has linked the amyloid-beta (Aβ) peptide to neurological dysfunction in Alzheimer's disease (AD). Insoluble Aβ plaques in the AD patient brain contain high concentrations of advanced glycation end-products (AGEs) as well as transition metal ions. This research elucidated the roles of Aβ, sugars, and Cu2+ in the oxidative stress mechanism of AD at the molecular level. Mass spectral (MS) analysis of the reactions of Aβ with two representative sugars, ribose-5-phosphate (R5P) and methylglyoxal (MG), revealed Lys-16 and Arg-5 as the primary glycation sites. Quantitative analysis of superoxide [Formula: see text] production by a cyt c assay showed that Lys-16 generated four times as much [Formula: see text] as Arg-5. Lys-16 and Arg-5 in Aβ1-40 are both adjacent to histidine residues, which are suggested to catalyze glycation. Additionally, Lys-16 is close to the central hydrophobic core (Leu-17-Ala-21) and to His-13, both of which are known to lower the pKa of the residue, leading to increased deprotonation of the amine and an enhanced glycation reactivity compared to Arg-5. Gel electrophoresis results indicated that all three components of AD plaques-Aβ1-40, sugars, and Cu2+-are necessary for DNA damage. It is concluded that the glycation of Aβ1-40 with sugars generates significant amounts of [Formula: see text], owing to the rapid glycation of Lys-16 and Arg-5. In the presence of Cu2+, [Formula: see text] converts to hydroxyl radical (HO·), the source of oxidative stress in AD.
Collapse
Affiliation(s)
| | - Sydney O Shuster
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, 05753, USA
| | - Nathaniel D Durfee
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, 05753, USA
| | - Gregory J K Bowe
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, 05753, USA
| | - Nathaniel J Henning
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, 05753, USA
| | - Staci A Hill
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, 05753, USA
| | - Geoffrey D Vrla
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, 05753, USA
| | - David R Stillman
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, 05753, USA
| | - Kelly M Suralik
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, 05753, USA
| | - Roger K Sandwick
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, 05753, USA
| | - Sunhee Choi
- Department of Chemistry and Biochemistry, Middlebury College, Middlebury, VT, 05753, USA.
| |
Collapse
|