Leigh Syndrome Due to NDUFV1 Mutations Initially Presenting as LBSL

NDUFV1-Related Mitochondrial Complex-1 Disorders: A Retrospective Case Series and Literature Review

BACKGROUND

Pathogenic variants in the NDUFV1 gene disrupt mitochondrial complex I, leading to neuroregression with leukoencephalopathy and basal ganglia involvement on neuroimaging. This study aims to provide a concise review on NDUFV1-related disorders while adding the largest cohort from a single center to the existing literature.

METHODS

We retrospectively collected genetically proven cases of NDUFV1 pathogenic variants from our center over the last decade and explored reported instances in existing literature. Magnetic resonance imaging (MRI) patterns observed in these patients were split into three types-Leigh (putamen, basal ganglia, thalamus, and brainstem involvement), mitochondrial leukodystrophy (ML) (cerebral white matter involvement with cystic cavitations), and mixed (both).

RESULTS

Analysis included 44 children (seven from our center and 37 from literature). The most prevalent comorbidities were hypertonia, ocular abnormalities, feeding issues, and hypotonia at onset. Children with the Leigh-type MRI pattern exhibited significantly higher rates of breathing difficulties, whereas those with a mixed phenotype had a higher prevalence of dystonia. The c.1156C>T variant in exon 8 of the NDUFV1 gene was the most common variant among individuals of Asian ethnicity and is predominantly associated with irritability and dystonia. Seizures and Leigh pattern of MRI of the brain was found to be less commonly associated with this variant. Higher rate of mortality was observed in children with Leigh-type pattern on brain MRI and those who did not receive mitochondrial cocktail.

CONCLUSIONS

MRI phenotyping might help predict outcome. Appropriate and timely treatment with mitochondrial cocktail may reduce the probability of death and may positively impact the long-term outcomes, regardless of the genetic variant or age of onset.

Comprehensive analysis of lactate-related gene profiles and immune characteristics in lupus nephritis

Objectives

The most frequent cause of kidney damage in systemic lupus erythematosus (SLE) is lupus nephritis (LN), which is also a significant risk factor for morbidity and mortality. Lactate metabolism and protein lactylation might be related to the development of LN. However, there is still a lack of relative research to prove the hypothesis. Hence, this study was conducted to screen the lactate-related biomarkers for LN and analyze the underlying mechanism.

Methods

To identify differentially expressed genes (DEGs) in the training set (GSE32591, GSE127797), we conducted a differential expression analysis (LN samples versus normal samples). Then, module genes were mined using WGCNA concerning LN. The overlapping of DEGs, critical module genes, and lactate-related genes (LRGs) was used to create the lactate-related differentially expressed genes (LR-DEGs). By using a machine-learning algorithm, ROC, and expression levels, biomarkers were discovered. We also carried out an immune infiltration study based on biomarkers and GSEA.

Results

A sum of 1259 DEGs was obtained between LN and normal groups. Then, 3800 module genes in reference to LN were procured. 19 LR-DEGs were screened out by the intersection of DEGs, key module genes, and LRGs. Moreover, 8 pivotal genes were acquired via two machine-learning algorithms. Subsequently, 3 biomarkers related to lactate metabolism were obtained, including COQ2, COQ4, and NDUFV1. And these three biomarkers were enriched in pathways 'antigen processing and presentation' and 'NOD-like receptor signaling pathway'. We found that Macrophages M0 and T cells regulatory (Tregs) were associated with these three biomarkers as well.

Conclusion

Overall, the results indicated that lactate-related biomarkers COQ2, COQ4, and NDUFV1 were associated with LN, which laid a theoretical foundation for the diagnosis and treatment of LN.

The neuropathologic findings in a case of progressive cavitating leukoencephalopathy due to NDUFV1 pathogenic variants

Pathogenic variants in the NDUFV1 gene, which codes for complex I of the mitochondrial respiratory chain, have been associated with a variety of clinical phenotypes, including a progressive cavitating leukoencephalopathy. The neuropathology of NDUFV1-associated leukoencephalopathy is not well-described. We present a report of a 24-year-old female with two pathogenic variants in the NDUFV1 gene, together with antemortem skeletal muscle biopsy and postmortem neuropathologic examination. Autopsy neuropathology showed a cavitating leukoencephalopathy with extensive white matter involvement, regions of active demyelination, and sparing of the subcortical U-fibers. Muscle biopsy showed subtle but distinct histologic abnormalities by light microscopy, and ultrastructural analysis demonstrated mitochondrial abnormalities including abnormal subsarcolemmal mitochondrial accumulation, electron-dense inclusions, and enlarged mitochondria with abnormal cristae. Our report is the first comprehensive description of the neuropathology in a patient with compound heterozygous variants in the NDUFV1 gene and progressive cavitating leukoencephalopathy. This case is evidence of pathogenicity of one NDUFV1 variant (c.565 T > C, p.S189P), which has not been previously described as pathogenic. These findings, in combination with the ultrastructural abnormalities in the mitochondria by electron microscopy, support the mitochondrial nature of the pathology. Together, this case highlights the link between mitochondrial abnormalities and demyelinating processes in the central nervous system (CNS).

Mitochondrial protein dysfunction in pathogenesis of neurological diseases

Mitochondria are essential organelles for neuronal function and cell survival. Besides the well-known bioenergetics, additional mitochondrial roles in calcium signaling, lipid biogenesis, regulation of reactive oxygen species, and apoptosis are pivotal in diverse cellular processes. The mitochondrial proteome encompasses about 1,500 proteins encoded by both the nuclear DNA and the maternally inherited mitochondrial DNA. Mutations in the nuclear or mitochondrial genome, or combinations of both, can result in mitochondrial protein deficiencies and mitochondrial malfunction. Therefore, mitochondrial quality control by proteins involved in various surveillance mechanisms is critical for neuronal integrity and viability. Abnormal proteins involved in mitochondrial bioenergetics, dynamics, mitophagy, import machinery, ion channels, and mitochondrial DNA maintenance have been linked to the pathogenesis of a number of neurological diseases. The goal of this review is to give an overview of these pathways and to summarize the interconnections between mitochondrial protein dysfunction and neurological diseases.

Overexpression of NDUFV1 alleviates renal damage by improving mitochondrial function in unilateral ureteral obstruction model mice

Mitochondrial homeostasis plays essential role for the proper functioning of the kidney. NADH-ubiquinone oxidoreductase core subunit V1 (NDUFV1) is an enzyme in the complex I of electron transport chain (ETC) in mitochondria. In the present study, we examined the effects of NDUFV1 on renal function in unilateral ureteral obstruction (UUO) model mice. Our data showed that increased expression of NDUFV1 improves kidney function as evidenced by the decreases in blood urea nitrogen and serum creatinine in UUO mice. Moreover, NDUFV1 also maintains renal structures and alleviates renal fibrosis induced by UUO surgery. Mechanistically, NDUFV1 mitigates the increased oxidative stress in the kidney in UUO model mice. Meanwhile, increased expression of NDUFV1 in the kidney improves the integrity of the complex I and potentiates the complex I activity. Overall, these results indicate that the ETC complex I plays a beneficial role against renal dysfunction induced by acute kidney injury such as UUO. Therefore, NDUFV1 might be a druggable target for developing agents for dealing with disabled mitochondria-associated renal diseases.

Quantification of NADH:ubiquinone oxidoreductase (complex I) content in biological samples

Impairments in mitochondrial energy metabolism have been implicated in human genetic diseases associated with mitochondrial and nuclear DNA mutations, neurodegenerative and cardiovascular disorders, diabetes, and aging. Alteration in mitochondrial complex I structure and activity has been shown to play a key role in Parkinson's disease and ischemia/reperfusion tissue injury, but significant difficulty remains in assessing the content of this enzyme complex in a given sample. The present study introduces a new method utilizing native polyacrylamide gel electrophoresis in combination with flavin fluorescence scanning to measure the absolute content of complex I, as well as α-ketoglutarate dehydrogenase complex, in any preparation. We show that complex I content is 19 ± 1 pmol/mg of protein in the brain mitochondria, whereas varies up to 10-fold in different mouse tissues. Together with the measurements of NADH-dependent specific activity, our method also allows accurate determination of complex I catalytic turnover, which was calculated as 104 min-1 for NADH:ubiquinone reductase in mouse brain mitochondrial preparations. α-ketoglutarate dehydrogenase complex content was determined to be 65 ± 5 and 123 ± 9 pmol/mg protein for mouse brain and bovine heart mitochondria, respectively. Our approach can also be extended to cultured cells, and we demonstrated that about 90 × 103 complex I molecules are present in a single human embryonic kidney 293 cell. The ability to determine complex I content should provide a valuable tool to investigate the enzyme status in samples after in vivo treatment in mutant organisms, cells in culture, or human biopsies.