Genetic aberration analysis of mitochondrial respiratory complex I implications in the development of neurological disorders and their clinical significance

Unraveling the Interplay Between Metabolism and Neurodevelopment in Health and Disease

BACKGROUND

Neurodevelopment is a multifaceted and tightly regulated process essential for the formation, maturation, and functional specialization of the nervous system. It spans critical stages, including cellular proliferation, differentiation, migration, synaptogenesis, and synaptic pruning, which collectively establish the foundation for cognitive, behavioral, and emotional functions. Metabolism serves as a cornerstone for neurodevelopment, providing the energy and substrates necessary for biosynthesis, signaling, and cellular activities.

RESULTS

Key metabolic pathways, including glycolysis, lipid metabolism, and amino acid metabolism, support processes such as cell proliferation, myelination, and neurotransmitter synthesis. Crucial signaling pathways, such as insulin, mTOR, and AMPK, further regulate neuronal growth, synaptic plasticity, and energy homeostasis. Dysregulation of these metabolic processes is linked to a spectrum of neurodevelopmental disorders, including autism spectrum disorders (ASDs), intellectual disabilities, and epilepsy.

CONCLUSIONS

This review investigates the intricate interplay between metabolic processes and neurodevelopment, elucidating the molecular mechanisms that govern brain development and the pathogenesis of neurodevelopmental disorders. Additionally, it highlights potential avenues for the development of innovative strategies aimed at enhancing brain health and function.

Aging through the lens of mitochondrial DNA mutations and inheritance paradoxes

Mitochondrial DNA encodes essential components of the respiratory chain complexes, serving as the foundation of mitochondrial respiratory function. Mutations in mtDNA primarily impair energy metabolism, exerting far-reaching effects on cellular physiology, particularly in the context of aging. The intrinsic vulnerability of mtDNA is increasingly recognized as a key driver in the initiation of aging and the progression of its related diseases. In the field of aging research, it is critical to unravel the intricate mechanisms underpinning mtDNA mutations in living organisms and to elucidate the pathological consequences they trigger. Interestingly, certain effects, such as oxidative stress and apoptosis, may not universally accelerate aging as traditionally perceived. These phenomena demand deeper investigation and a more nuanced reinterpretation of current findings to address persistent scientific uncertainties. By synthesizing recent insights, this review seeks to clarify how pathogenic mtDNA mutations drive cellular senescence and systemic health deterioration, while also exploring the complex dynamics of mtDNA inheritance that may propagate these mutations. Such a comprehensive understanding could ultimately inform the development of innovative therapeutic strategies to counteract mitochondrial dysfunctions associated with aging.

Convergence between brain aging and Alzheimer's disease: Focus on mitochondria

Alzheimer's disease (AD) accounts for the majority of dementia cases, with aging being the primary risk factor for developing this neurodegenerative condition. Aging and AD share several characteristics, including the formation of amyloid plaques and neurofibrillary tangles, synaptic loss, and neuroinflammation. This overlap suggests that mechanisms driving the aging process might also promote AD; however, the underlying processes are not yet fully understood. In this narrative review, we will focus on the role of mitochondria, not only as the "powerhouse of the cell", but also in programmed cell death, immune response, macromolecular synthesis, and calcium regulation. We will explore both the common changes between aging and AD and the differences between them. Additionally, we will provide an overview of interventions aimed at maintaining mitochondrial function in an attempt to slow the progression of AD. This will include a discussion of antioxidant molecules, factors that trigger mitochondrial biogenesis, compounds capable of restoring the fission/fusion balance, and a particular focus on recent techniques for mitochondrial DNA gene therapy.

Mitochondrial endogenous substance transport-inspired nanomaterials for mitochondria-targeted gene delivery

Mitochondrial genome (mtDNA) independent of nuclear gene is a set of double-stranded circular DNA that encodes 13 proteins, 2 ribosomal RNAs and 22 mitochondrial transfer RNAs, all of which play vital roles in functions as well as behaviors of mitochondria. Mutations in mtDNA result in various mitochondrial disorders without available cures. However, the manipulation of mtDNA via the mitochondria-targeted gene delivery faces formidable barriers, particularly owing to the mitochondrial double membrane. Given the fact that there are various transport channels on the mitochondrial membrane used to transfer a variety of endogenous substances to maintain the normal functions of mitochondria, mitochondrial endogenous substance transport-inspired nanomaterials have been proposed for mitochondria-targeted gene delivery. In this review, we summarize mitochondria-targeted gene delivery systems based on different mitochondrial endogenous substance transport pathways. These are categorized into mitochondrial steroid hormones import pathways-inspired nanomaterials, protein import pathways-inspired nanomaterials and other mitochondria-targeted gene delivery nanomaterials. We also review the applications and challenges involved in current mitochondrial gene editing systems. This review delves into the approaches of mitochondria-targeted gene delivery, providing details on the design of mitochondria-targeted delivery systems and the limitations regarding the various technologies. Despite the progress in this field is currently slow, the ongoing exploration of mitochondrial endogenous substance transport and mitochondrial biological phenomena may act as a crucial breakthrough in the targeted delivery of gene into mitochondria and even the manipulation of mtDNA.

The lysosomal β-glucocerebrosidase strikes mitochondria: implications for Parkinson's therapeutics

Parkinson's disease is a neurodegenerative disorder primarily known for typical motor features that arise due to the loss of dopaminergic neurons in the substantia nigra. However, the precise molecular aetiology of the disease is still unclear. Several cellular pathways have been linked to Parkinson's disease, including the autophagy-lysosome pathway, α-synuclein aggregation and mitochondrial function. Interestingly, the mechanistic link between GBA1, the gene that encodes for lysosomal β-glucocerebrosidase (GCase), and Parkinson's disease lies in the interplay between GCase functions in the lysosome and mitochondria. GCase mutations alter mitochondria-lysosome contact sites. In the lysosome, reduced GCase activity leads to glycosphingolipid build-up, disrupting lysosomal function and autophagy, thereby triggering α-synuclein accumulation. Additionally, α-synuclein aggregates reduce GCase activity, creating a self-perpetuating cycle of lysosomal dysfunction and α-synuclein accumulation. GCase can also be imported into the mitochondria, where it promotes the integrity and function of mitochondrial complex I. Thus, GCase mutations that impair its normal function increase oxidative stress in mitochondria, the compartment where dopamine is oxidized. In turn, the accumulation of oxidized dopamine adducts further impairs GCase activity, creating a second cycle of GCase dysfunction. The oxidative state triggered by GCase dysfunction can also induce mitochondrial DNA damage which, in turn, can cause dopaminergic cell death. In this review, we highlight the pivotal role of GCase in Parkinson's disease pathogenesis and discuss promising examples of GCase-based therapeutics, such as gene and enzyme replacement therapies, small molecule chaperones and substrate reduction therapies, among others, as potential therapeutic interventions.

Multiomics analysis reveals serine catabolism as a potential therapeutic target for MELAS

Mitochondrial disease is a devastating genetic disorder, with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) and m.3243A>G being the most common phenotype and genotype, respectively. The treatment for MELAS patients is still less effective. Here, we performed transcriptomic and proteomic analysis in muscle tissue of MELAS patients, and discovered that the expression of molecules involved in serine catabolism were significantly upregulated, and serine hydroxymethyltransferase 2 (SHMT2) increased significantly in both the mRNA and protein levels. The SHMT2 protein level was also increased in myoblasts with m.3243A>G mutation, which was transdifferentiated from patients derived fibroblasts, accompanying with the decreased nicotinamide adenine dinucleotide (NAD+)/reduced NAD+ (NADH) ratio and cell viability. After treating with SHMT2 inhibitor (SHIN1), the NAD+/NADH ratio and cell viability in MELAS myoblasts increased significantly. Taken together, our study indicates that enhanced serine catabolism plays an important role in the pathogenesis of MELAS and that SHIN1 can be a potential small molecule for the treatment of this disease.

The mechanisms of mitochondrial abnormalities that contribute to sleep disorders and related neurodegenerative diseases

Sleep is a highly intricate biological phenomenon, and its disorders play a pivotal role in numerous diseases. However, the specific regulatory mechanisms remain elusive. In recent years, the role of mitochondria in sleep disorders has gained considerable attention. Sleep deprivation not only impairs mitochondrial morphology but also decreases the number of mitochondria and triggers mitochondrial dysfunction. Furthermore, mitochondrial dysfunction has been implicated in the onset and progression of various sleep disorder-related neurological diseases, especially neurodegenerative conditions. Therefore, a greater understanding of the impact of sleep disorders on mitochondrial dysfunction may reveal new therapeutic targets for neurodegenerative diseases. In this review, we comprehensively summarize the recent key findings on the mechanisms underlying mitochondrial dysfunction caused by sleep disorders and their role in initiating or exacerbating common neurodegenerative diseases. In addition, we provide fresh insights into the diagnosis and treatment of sleep disorder-related diseases.

Altered Oxidative Phosphorylation Confers Vulnerability on IDH1-Mutant Leukemia Cells: Is This Therapeutically Tractable?

SUMMARY

Isocitrate dehydrogenase (IDH)-mutant acute myeloid leukemia (AML) is treatable with inhibitors of mutant IDH and also responds well to combination therapies including venetoclax, but most patients with IDH-mutant AML either never achieve complete remission or relapse because mutant hematopoietic stem cells persist despite treatment. An interesting new study in Blood Cancer Discovery characterizes a specific vulnerability in the mitochondrial oxidative phosphorylation system in preleukemic hematopoietic stem cells from patients with IDH1 mutations that is not present in those with IDH2 mutations; will this susceptibility prove amenable to therapy? See related article by Landberg et al., p. 114 (10).

The Role of Exercise in Maintaining Mitochondrial Proteostasis in Parkinson's Disease

Parkinson's disease (PD) is the second most common rapidly progressive neurodegenerative disease and has serious health and socio-economic consequences. Mitochondrial dysfunction is closely related to the onset and progression of PD, and the use of mitochondria as a target for PD therapy has been gaining traction in terms of both recognition and application. The disruption of mitochondrial proteostasis in the brain tissue of PD patients leads to mitochondrial dysfunction, which manifests as mitochondrial unfolded protein response, mitophagy, and mitochondrial oxidative phosphorylation. Physical exercise is important for the maintenance of human health, and has the great advantage of being a non-pharmacological therapy that is non-toxic, low-cost, and universally applicable. In this review, we investigate the relationships between exercise, mitochondrial proteostasis, and PD and explore the role and mechanisms of mitochondrial proteostasis in delaying PD through exercise.