bims-smemid 2023-07-23 papers

on Stress metabolism in mitochondrial dysfunction

Issue of 2023–07–23
six papers selected by
Deepti Mudartha, The International Institute of Molecular Mechanisms and Machines

Tricarboxylic acid (TCA) cycle, sphingolipid, and phosphatidylcholine metabolism are dysregulated in T. gondii infection-induced cachexia.
S-Nitrosylation-mediated dysfunction of TCA cycle enzymes in synucleinopathy studied in postmortem human brains and hiPSC-derived neurons.
Pyruvate Dehydrogenase Kinase 1 inhibition mediated oxidative phosphorylation enhancement in cartilage promotes osteoarthritis progression.
Overexpression of peroxisome proliferator-activated receptor γ co-activator-1⍺ (PGC-1⍺) in Chinese hamster ovary cells increases oxidative metabolism and IgG productivity.
Adaptative response to changes in pyruvate metabolism on the epigenetic landscapes and transcriptomics of bovine embryos.
Elevation of NAD+ by nicotinamide riboside spares spinal cord tissue from injury and promotes locomotor recovery.

Heliyon. 2023 Jul;9(7): e17411

Tricarboxylic acid (TCA) cycle, sphingolipid, and phosphatidylcholine metabolism are dysregulated in T. gondii infection-induced cachexia.

Tzu-Yu Feng, Stephanie J Melchor, Xiao-Yu Zhao, Haider Ghumman, Mark Kester, Todd E Fox, Sarah E Ewald.

  Cachexia is a life-threatening disease characterized by chronic, inflammatory muscle wasting and systemic metabolic impairment. Despite its high prevalence, there are no efficacious therapies for cachexia. Mice chronically infected with the protozoan parasite Toxoplasma gondii represent a novel animal model recapitulating the chronic kinetics of cachexia. To understand how perturbations to metabolic tissue homeostasis influence circulating metabolite availability we used mass spectrometry analysis. Despite the significant reduction in circulating triacylglycerides, non-esterified fatty acids, and glycerol, sphingolipid long-chain bases and a subset of phosphatidylcholines (PCs) were significantly increased in the sera of mice with T. gondii infection-induced cachexia. In addition, the TCA cycle intermediates α-ketoglutarate, 2-hydroxyglutarate, succinate, fumarate, and malate were highly depleted in cachectic mouse sera. Sphingolipids and their de novo synthesis precursors PCs are the major components of the mitochondrial membrane and regulate mitochondrial function consistent with a causal relationship in the energy imbalance driving T. gondii-induced chronic cachexia.

Keywords:  Cachexia; Ceramides; Lipid rebound; Liver atrophy; Sphingolipids; TCA cycle; Toxoplasma gondii

DOI:  https://doi.org/10.1016/j.heliyon.2023.e17411
Cell Chem Biol. 2023 Jul 04. pii: S2451-9456(23)00196-4. [Epub ahead of print]

S-Nitrosylation-mediated dysfunction of TCA cycle enzymes in synucleinopathy studied in postmortem human brains and hiPSC-derived neurons.

Paschalis-Thomas Doulias, Hongmei Yang, Alexander Y Andreyev, Nima Dolatabadi, Henry Scott, Charlene K Raspur, Parth R Patel, Tomohiro Nakamura, Steven R Tannenbaum, Harry Ischiropoulos, Stuart A Lipton.

A causal relationship between mitochondrial metabolic dysfunction and neurodegeneration has been implicated in synucleinopathies, including Parkinson disease (PD) and Lewy body dementia (LBD), but underlying mechanisms are not fully understood. Here, using human induced pluripotent stem cell (hiPSC)-derived neurons with mutation in the gene encoding α-synuclein (αSyn), we report the presence of aberrantly S-nitrosylated proteins, including tricarboxylic acid (TCA) cycle enzymes, resulting in activity inhibition assessed by carbon-labeled metabolic flux experiments. This inhibition principally affects α-ketoglutarate dehydrogenase/succinyl coenzyme-A synthetase, metabolizing α-ketoglutarate to succinate. Notably, human LBD brain manifests a similar pattern of aberrantly S-nitrosylated TCA enzymes, indicating the pathophysiological relevance of these results. Inhibition of mitochondrial energy metabolism in neurons is known to compromise dendritic length and synaptic integrity, eventually leading to neuronal cell death. Our evidence indicates that aberrant S-nitrosylation of TCA cycle enzymes contributes to this bioenergetic failure.

DOI: https://doi.org/10.1016/j.chembiol.2023.06.018
BMC Musculoskelet Disord. 2023 Jul 20. 24(1): 597

Pyruvate Dehydrogenase Kinase 1 inhibition mediated oxidative phosphorylation enhancement in cartilage promotes osteoarthritis progression.

Xian Yang, Qingsong Jiang, Tiankuo Luan, Chao Yu, Zhibo Liu, Ting Wang, Jingyuan Wan, Jiayu Huang, Ke Li.

  Osteoarthritis (OA) is a common disease characterized by cartilage degradation. Growing evidence showed that glucose metabolism impacts joint homeostasis and an imbalance between glycolysis and oxidative phosphorylation (OXPHOS) may exacerbate OA progression, however, a definitive link is yet to be established. Here, we report that pyruvate metabolism and oxidative phosphorylation pathway is enriched in OA cartilage through gene set enrichment analysis (GSEA) and expression of Pyruvate Dehydrogenase Kinase 1 (PDK1), an enzyme that can phosphorylate Pyruvate Dehydrogenase (PDH), and inhibit pyruvate fluxes into the tricarboxylic acid (TCA) cycle and to OXPHOS, in articular cartilage is notably reduced through destabilization of medial meniscus (DMM). Moreover, by inhibiting PDK1, cartilage loss is markedly accelerated in DMM-induced OA through extracellular matrix (ECM) degradation and apoptosis of chondrocytes. These results indicate that PDK1 is involved in the progression of OA through accelerating cartilage matrix degradation and synovium inflammation to ameliorate cartilage degeneration.

Keywords:  ECM; Glucose metabolism; Inflammation; Osteoarthritis; PDK1

DOI:  https://doi.org/10.1186/s12891-023-06585-6
Metab Eng. 2023 Jul 18. pii: S1096-7176(23)00111-8. [Epub ahead of print]

Overexpression of peroxisome proliferator-activated receptor γ co-activator-1⍺ (PGC-1⍺) in Chinese hamster ovary cells increases oxidative metabolism and IgG productivity.

Sarah A Sacco, Allison G McAtee Pereira, Irina Trenary, Kevin D Smith, Michael J Betenbaugh, Jamey D Young.

Chinese hamster ovary (CHO) cells are used extensively to produce protein therapeutics, such as monoclonal antibodies (mAbs), in the biopharmaceutical industry. MAbs are large proteins that are energetically demanding to synthesize and secrete; therefore, high-producing CHO cell lines that are engineered for maximum metabolic efficiency are needed to meet increasing demands for mAb production. Previous studies have identified that high-producing cell lines possess a distinct metabolic phenotype when compared to low-producing cell lines. In particular, it was found that high mAb production is correlated to lactate consumption and elevated TCA cycle flux. We hypothesized that enhancing flux through the mitochondrial TCA cycle and oxidative phosphorylation would lead to increased mAb productivities and final titers. To test this hypothesis, we overexpressed peroxisome proliferator-activated receptor γ co-activator-1⍺ (PGC-1⍺), a gene that promotes mitochondrial metabolism, in an IgG-producing parental CHO cell line. Stable cell pools overexpressing PGC-1⍺ exhibited increased oxygen consumption, indicating increased mitochondrial metabolism, as well as increased mAb specific productivity compared to the parental line. We also performed 13C metabolic flux analysis (MFA) to quantify how PGC-1⍺ overexpression alters intracellular metabolic fluxes, revealing not only increased TCA cycle flux, but global upregulation of cellular metabolic activity. This study demonstrates the potential of rationally engineering the metabolism of industrial cell lines to improve overall mAb productivity and to increase the abundance of high-producing clones in stable cell pools.

DOI: https://doi.org/10.1016/j.ymben.2023.07.005
Sci Rep. 2023 07 17. 13(1): 11504

Adaptative response to changes in pyruvate metabolism on the epigenetic landscapes and transcriptomics of bovine embryos.

Aldcejam Martins da Fonseca Junior, Jessica Ispada, Erika Cristina Dos Santos, Camila Bruna de Lima, João Vitor Alcantara da Silva, Erika Paulson, Daniel Estanislao Goszczynski, Marcelo Demarchi Goissis, Pablo Juan Ross, Marcella Pecora Milazzotto.

The epigenetic reprogramming that occurs during the earliest stages of embryonic development has been described as crucial for the initial events of cell specification and differentiation. Recently, the metabolic status of the embryo has gained attention as one of the main factors coordinating epigenetic events. In this work, we investigate the link between pyruvate metabolism and epigenetic regulation by culturing bovine embryos from day 5 in the presence of dichloroacetate (DCA), a pyruvate analog that increases the pyruvate to acetyl-CoA conversion, and iodoacetate (IA), which inhibits the glyceraldehyde-3-phosphate dehydrogenase (GAPDH), leading to glycolysis inhibition. After 8 h of incubation, both DCA and IA-derived embryos presented higher mitochondrial membrane potential. Nevertheless, in both cases, lower levels of acetyl-CoA, ATP-citrate lyase and mitochondrial membrane potential were found in blastocysts, suggesting an adaptative metabolic response, especially in the DCA group. The metabolic alteration found in blastocysts led to changes in the global pattern of H3K9 and H3K27 acetylation and H3K27 trimethylation. Transcriptome analysis revealed that such alterations resulted in molecular differences mainly associated to metabolic processes, establishment of epigenetic marks, control of gene expression and cell cycle. The latter was further confirmed by the alteration of total cell number and cell differentiation in both groups when compared to the control. These results corroborate previous evidence of the relationship between the energy metabolism and the epigenetic reprogramming in preimplantation bovine embryos, reinforcing that the culture system is decisive for precise epigenetic reprogramming, with consequences for the molecular control and differentiation of cells.

DOI: https://doi.org/10.1038/s41598-023-38686-6
Exp Neurol. 2023 Jul 14. pii: S0014-4886(23)00164-4. [Epub ahead of print] 114479

Elevation of NAD+ by nicotinamide riboside spares spinal cord tissue from injury and promotes locomotor recovery.

Mariajose Metcalfe, Brian T David, Brett C Langley, Caitlin E Hill.

  Spinal cord injury (SCI)-induced tissue damage spreads to neighboring spared cells in the hours, days, and weeks following injury, leading to exacerbation of tissue damage and functional deficits. Among the biochemical changes is the rapid reduction of cellular nicotinamide adenine dinucleotide (NAD+), an essential coenzyme for energy metabolism and an essential cofactor for non-redox NAD+-dependent enzymes with critical functions in sensing and repairing damaged tissue. NAD+ depletion propagates tissue damage. Augmenting NAD+ by exogenous application of NAD+, its synthesizing enzymes, or its cellular precursors mitigates tissue damage. Nicotinamide riboside (NR) is considered to be one of the most promising NAD+ precursors for clinical application due to its ability to safely and effectively boost cellular NAD+ synthesis in rats and humans. Moreover, various preclinical studies have demonstrated that NR can provide tissue protection. Despite these promising findings, little is known about the potential benefits of NR in the context of SCI. In the current study, we tested whether NR administration could effectively increase NAD+ levels in the injured spinal cord and whether this augmentation of NAD+ would promote spinal cord tissue protection and ultimately lead to improvements in locomotor function. Our findings indicate that administering NR (500 mg/kg) via intraperitoneal route, four days before and two weeks after a mid-thoracic contusion-SCI injury, effectively doubles NAD+ levels in the spinal cord of Long-Evans rats. Moreover, NR administration plays a protective role in preserving spinal cord tissue post-injury, particularly in neurons and axons, as evident from the observed gray and white matter sparing. Additionally, it enhances motor function, as evaluated through the BBB subscore and missteps on the horizontal ladderwalk. Collectively, these findings demonstrate that administering NR, a precursor of NAD+ increases NAD+ within the injured spinal cord and effectively mitigates the tissue damage and functional decline that occurs following SCI.

Keywords:  Nicotinamide adenine dinucleotide; Nicotinamide riboside; Spinal cord injury

DOI:  https://doi.org/10.1016/j.expneurol.2023.114479