bims-mignad 2024-10-20 papers

Issue of 2024–10–20
four papers selected by
Melisa Emel Ermert, Amsterdam UMC

J Alzheimers Dis. 2024 ;101(s1): S467-S477

Supplementation with NAD+ Precursors for Treating Alzheimer's Disease: A Metabolic Approach.

Background: Alzheimer's disease (AD) is a progressive neurocognitive disorder. There is no cure for AD. Maintenance on intracellular levels of nicotinamide adenine dinucleotide (NAD+) has been reported to be a promising therapeutic strategy for the treatment of AD. NAD+ precursors that represent candidate targets include nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR).
Objective: This systematic review provides insights into the potential therapeutic value of NAD+ precursors including NMN and NR, for the treatment of AD using preclinical and clinical studies published in the last 5 years.
Methods: The Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) protocol was followed to systematically search the literature using two databases.
Results: We found 3 studies that used NMN to treat AD in preclinical murine models. However, human clinical trials using NMN as a therapeutic intervention in AD was not available in the current literature. We also found 4 studies that investigated the potential benefits of NR for the treatment of AD in preclinical models. We also found 2 human clinical trials that showed marked improvements in plasma and neuroimaging biomarkers, and cognitive measures following supplementation with NR.
Conclusions: Results of preclinical and clinical studies confirm the potential benefits of NAD+ precursors for the treatment of AD. However, further clinical studies are required to confirm the increasingly important value of NAD+ precursors as effective pharmacological interventions in the clinic.

Keywords: Alzheimer’s disease; NAD+; amyloid; dementia; nicotinamide; sirtuins

DOI: https://doi.org/10.3233/JAD-231277

bioRxiv. 2024 Oct 08. pii: 2024.10.07.617073. [Epub ahead of print]

Direct mitochondrial import of lactate supports resilient carbohydrate oxidation.

Lactate is the highest turnover circulating metabolite in mammals. While traditionally viewed as a waste product, lactate is an important energy source for many organs, but first must be oxidized to pyruvate for entry into the tricarboxylic acid cycle (TCA cycle). This reaction is thought to occur in the cytosol, with pyruvate subsequently transported into mitochondria via the mitochondrial pyruvate carrier (MPC). Using 13 C stable isotope tracing, we demonstrated that lactate is oxidized in the myocardial tissue of mice even when the MPC is genetically deleted. This MPC-independent lactate import and mitochondrial oxidation is dependent upon the monocarboxylate transporter 1 (MCT1/ Slc16a1 ). Mitochondria isolated from the myocardium without MCT1 exhibit a specific defect in mitochondrial lactate, but not pyruvate, metabolism. The import and subsequent mitochondrial oxidation of lactate by mitochondrial lactate dehydrogenase (LDH) acts as an electron shuttle, generating sufficient NADH to support respiration even when the TCA cycle is disrupted. In response to diverse cardiac insults, animals with hearts lacking MCT1 undergo rapid progression to heart failure with reduced ejection fraction. Thus, the mitochondrial import and oxidation of lactate enables carbohydrate entry into the TCA cycle to sustain cardiac energetics and maintain myocardial structure and function under stress conditions.

DOI: https://doi.org/10.1101/2024.10.07.617073

J Transl Med. 2024 Oct 15. 22(1): 941

Mitochondrial transplantation: a promising strategy for treating degenerative joint diseases.

Hong Luo, Yue Lai, Weili Tang, Guoyou Wang, Jianlin Shen, Huan Liu.

The prevalence of age-related degenerative joint diseases, particularly intervertebral disc degeneration and osteoarthritis, is increasing, thereby posing significant challenges for the elderly population. Mitochondrial dysfunction is a critical factor in the etiology and progression of these disorders. Therapeutic interventions that incorporate mitochondrial transplantation exhibit considerable promise by increasing mitochondrial numbers and improving their functionality. Existing evidence suggests that exogenous mitochondrial therapy improves clinical outcomes for patients with degenerative joint diseases. This review elucidates the mitochondrial abnormalities associated with degenerative joint diseases and examines the mechanisms of mitochondrial intercellular transfer and artificial mitochondrial transplantation. Furthermore, therapeutic strategies for mitochondrial transplantation in degenerative joint diseases are synthesized, and the concept of engineered mitochondrial transplantation is proposed.

Keywords: Degenerative joint diseases; Engineered mitochondria; Intervertebral disc degeneration; Mitochondrial transplantation; Osteoarthritis

DOI: https://doi.org/10.1186/s12967-024-05752-0

Nat Commun. 2024 Oct 17. 15(1): 8971

Methionine-SAM metabolism-dependent ubiquinone synthesis is crucial for ROS accumulation in ferroptosis induction.

Chaoyi Xia, Pinghui Peng, Wenxia Zhang, Xiyue Xing, Xin Jin, Jianlan Du, Wanting Peng, Fengqi Hao, Zhexuan Zhao, Kejian Dong, Miaomiao Tian, Yunpeng Feng, Xueqing Ba, Min Wei, Yang Wang.

Ferroptosis is a cell death modality in which iron-dependent lipid peroxides accumulate on cell membranes. Cysteine, a limiting substrate for the glutathione system that neutralizes lipid peroxidation and prevents ferroptosis, can be converted by cystine reduction or synthesized from methionine. However, accumulating evidence shows methionine-based cysteine synthesis fails to effectively rescue intracellular cysteine levels upon cystine deprivation and is unable to inhibit ferroptosis. Here, we report that methionine-based cysteine synthesis is tissue-specific. Unexpectedly, we find that rather than inhibiting ferroptosis, methionine in fact plays an essential role during cystine deprivation-induced ferroptosis. Methionine-derived S-adenosylmethionine (SAM) contributes to methylation-dependent ubiquinone synthesis, which leads to lipid peroxides accumulation and subsequent ferroptosis. Moreover, SAM supplementation synergizes with Imidazole Ketone Erastin in a tumor growth suppression mouse model. Inhibiting the enzyme that converts methionine to SAM protects heart tissue from Doxorubicin-induced and ferroptosis-driven cardiomyopathy. This study broadens our understanding about the intersection of amino acid metabolism and ferroptosis regulation, providing insight into the underlying mechanisms and suggesting the methionine-SAM axis is a promising therapeutic strategy to treat ferroptosis-related diseases.

DOI: https://doi.org/10.1038/s41467-024-53380-5