A technology for modulating mitochondrial serine catabolism for treating diseases involving NADH imbalance and respiratory impairment

Background

Mitochondrial function is central to cellular energy production, primarily through the process of oxidative phosphorylation, which relies on the electron transport chain (ETC) to recycle NADH to NAD+ and generate ATP. In healthy cells, this balance between NADH and NAD+ is tightly regulated to support critical metabolic processes, including aspartate and nucleotide synthesis. However, in a variety of pathological conditions such as hypoxia, mitochondrial diseases (e.g., Leigh Syndrome), ischemic injuries (like heart attack and stroke), and as a side effect of certain drugs (such as metformin), the ETC becomes impaired. This leads to an accumulation of NADH, disrupting cellular metabolism and contributing to disease progression. The need for effective strategies to manage NADH levels and restore redox balance is therefore a significant challenge in the treatment of these disorders.

Current approaches to address elevated NADH and respiratory impairment are limited and often inadequate. Traditional therapies focus on symptomatic relief or attempt to bypass defective components of the ETC, but they do not directly address the persistent generation of NADH from alternative metabolic pathways, such as mitochondrial serine catabolism. Notably, enzymes like MTHFD2 remain active even at high NADH concentrations, continuing to produce NADH when other pathways are suppressed. This unique property undermines the effectiveness of interventions that rely solely on inhibiting the ETC or supplementing downstream metabolites. As a result, pathological NADH accumulation persists, leading to impaired biosynthesis, cellular stress, and poor clinical outcomes. There is a clear unmet need for targeted strategies that can modulate specific metabolic pathways contributing to NADH overload, especially under conditions where conventional treatments fall short.

Technology

This technology offers a targeted approach for managing diseases linked to elevated NADH levels and impaired cellular respiration by modulating mitochondrial serine catabolism. It focuses on the mitochondrial enzymes SHMT2 and MTHFD2, which continue to generate NADH even when other metabolic pathways are suppressed due to high NADH concentrations, such as during hypoxia or mitochondrial dysfunction. By administering small-molecule inhibitors of SHMT2 or MTHFD2, using antifolates, or implementing dietary serine restriction, this method reduces pathological NADH accumulation, thereby restoring the NADH/NAD+ balance. This normalization is crucial for maintaining essential metabolic functions, including aspartate and nucleotide synthesis. Conversely, the pathway can be manipulated to increase NADH-induced stress in tumor cells, especially when combined with electron transport chain inhibitors, offering a flexible therapeutic strategy for both metabolic disorders and cancer.

What differentiates this technology is its unique exploitation of the mitochondrial serine catabolic pathway as a major source of NADH under respiratory impairment. Unlike other NADH-generating enzymes, MTHFD2 remains active even at high NADH concentrations, making it a persistent contributor to metabolic imbalance in disease states. The approach is supported by extensive experimental evidence, including tracer studies, genetic and pharmacological interventions, and animal and human disease models, demonstrating its efficacy in normalizing NADH/NAD+ ratios and improving disease outcomes. Additionally, the technology’s versatility—encompassing pharmaceutical inhibitors, dietary modifications, and combination therapies—enables tailored interventions for a range of conditions, from mitochondrial diseases and ischemic injuries to enhancing or sensitizing cancer therapies, setting it apart from conventional metabolic treatments.

Benefits

• Restores NADH/NAD+ balance in diseases with respiratory impairment by modulating mitochondrial serine catabolism.
• Reduces pathological NADH accumulation to improve metabolic functions such as aspartate and nucleotide synthesis.
• Offers therapeutic options for mitochondrial disorders, ischemic injuries, and drug-induced ETC dysfunction.
• Enables cancer treatment by increasing NADH-induced stress in tumor cells when combined with ETC inhibitors.
• Supports multiple administration routes including small-molecule inhibitors, antifolates, and dietary serine restriction.
• Demonstrated efficacy in cellular, animal, and human disease models, including Leigh Syndrome and hypoxia-related conditions.
• Improves cell growth and survival under hypoxia or mitochondrial dysfunction by normalizing metabolic pathways.

Applications

• Treatment of mitochondrial diseases
• Therapy for ischemic injuries
• Adjunct cancer treatment
• Enhancing metformin therapy
• Dietary intervention for NADH disorders

Additional info

This technology addresses respiratory impairment by modulating mitochondrial serine catabolism, specifically targeting SHMT2 and MTHFD2. Because MTHFD2 resists NADH-mediated inhibition, it drives pathological NADH accumulation during mitochondrial dysfunction. Inhibiting this pathway via small molecules, antifolates, or dietary restriction restores the NADH/NAD+ balance and essential biosynthetic flux. Conversely, synergistic activation of this pathway with electron transport chain inhibitors can be used to induce metabolic stress in malignant cells.