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Nutrients Aug 2022Riboflavin is an essential micronutrient and a precursor of flavin mononucleotide and flavin adenine dinucleotide for maintaining cell homeostasis. Riboflavin deficiency...
Riboflavin is an essential micronutrient and a precursor of flavin mononucleotide and flavin adenine dinucleotide for maintaining cell homeostasis. Riboflavin deficiency (RD) induces cell apoptosis. Endoplasmic reticulum (ER) stress is considered to induce apoptosis, and C/EBP homologous protein (CHOP) is a key pathway involved in this process. However, whether RD-induced apoptosis is mediated by ER stress and the CHOP pathway remains unclear and needs further investigation. Therefore, the current study presents the effect of RD on ER stress and apoptosis in the human hepatoma cell line (HepG2). Firstly, cells were cultured in a RD medium (4.55 nM riboflavin) and a control (CON) medium (1005 nM riboflavin). We conducted an observation of cell microstructure characterization and determining apoptosis. Subsequently, 4-phenyl butyric acid (4-PBA), an ER stress inhibitor, was used in HepG2 cells to investigate the role of ER stress in RD-induced apoptosis. Finally, CHOP siRNA was transfected into HepG2 cells to validate whether RD triggered ER stress-mediated apoptosis by the CHOP pathway. The results show that RD inhibited cell proliferation and caused ER stress, as well as increased the expression of ER stress markers (CHOP, 78 kDa glucose-regulated protein, activating transcription factor 6) (p < 0.05). Furthermore, RD increased the cell apoptosis rate, enhanced the expression of proapoptotic markers (B-cell lymphoma 2-associated X, Caspase 3), and decreased the expression of the antiapoptotic marker (B-cell lymphoma 2) (p < 0.05). The 4-PBA treatment and CHOP knockdown markedly alleviated RD-induced cell apoptosis. These results demonstrate that RD induces cell apoptosis by triggering ER stress and the CHOP pathway.
Topics: Apoptosis; Endoplasmic Reticulum Stress; Hep G2 Cells; Humans; Proto-Oncogene Proteins c-bcl-2; Riboflavin; Riboflavin Deficiency; Signal Transduction; Transcription Factor CHOP
PubMed: 36014863
DOI: 10.3390/nu14163356 -
Frontiers in Pharmacology 2022Dysregulation of retinal metabolism is emerging as one of the major reasons for many inherited retinal diseases (IRDs), a leading cause of blindness worldwide. Thus, the... (Review)
Review
Dysregulation of retinal metabolism is emerging as one of the major reasons for many inherited retinal diseases (IRDs), a leading cause of blindness worldwide. Thus, the identification of a common regulator that can preserve or revert the metabolic ecosystem to homeostasis is a key step in developing a treatment for different forms of IRDs. Riboflavin (RF) and its derivatives (flavins), flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD), are essential cofactors for a wide range of cellular metabolic processes; hence, they are particularly critical in highly metabolically active tissues such as the retina. Patients with RF deficiency (ariboflavinosis) often display poor photosensitivity resulting in impaired low-light vision. We have identified a novel retina-specific RF binding protein called retbindin (Rtbdn), which plays a key role in retaining flavin levels in the neural retina. This role is mediated by its specific localization at the interface between the neural retina and retinal pigment epithelium (RPE), which is essential for metabolite and nutrient exchange. As a consequence of this vital function, Rtbdn's role in flavin utilization and metabolism in retinal degeneration is discussed. The principal findings are that Rtbdn helps maintain high levels of retinal flavins, and its ablation leads to an early-onset retinal metabolic dysregulation, followed by progressive degeneration of rod and cone photoreceptors. Lack of Rtbdn reduces flavin levels, forcing the neural retina to repurpose glucose to reduce the production of free radicals during ATP production. This leads to metabolic breakdown followed by retinal degeneration. Assessment of the role of Rtbdn in several preclinical retinal disease models revealed upregulation of its levels by several folds prior to and during the degenerative process. Ablation of Rtbdn in these models accelerated the rate of retinal degeneration. In agreement with these studies, we have also demonstrated that Rtbdn protects immortalized cone photoreceptor cells (661W cells) from light damage . This indicates that Rtbdn plays a neuroprotective role during retinal degeneration. Herein, we discussed the specific function of Rtbdn and its neuroprotective role in retinal metabolic homeostasis and its role in maintaining retinal health.
PubMed: 35873559
DOI: 10.3389/fphar.2022.919667 -
JIMD Reports Jul 2022In this report, we describe the case of an 11-year-old boy, who came to our attention for myalgia and muscle weakness, associated with inappetence and vomiting....
In this report, we describe the case of an 11-year-old boy, who came to our attention for myalgia and muscle weakness, associated with inappetence and vomiting. Hypertransaminasemia was also noted, with ultrasound evidence of hepatomegaly. Biochemical investigations revealed acylcarnitine and organic acid profiles resembling those seen in MADD, that is, multiple acyl-CoA dehydrogenase deficiencies (OMIM #231680) a rare inherited disorder of fatty acids, amino acids, and choline metabolism. The patient carried a single pathogenetic variant in the gene (c.524G>A, p.Arg175His) and no pathogenetic variant in the riboflavin (Rf) homeostasis related genes (, , , , ). Instead, compound heterozygosity was found in the gene (c.512C>G, p.Ser171Cys; c.822C>A, p.Asn274Lys), coding for isobutyryl-CoA dehydrogenase (IBD), whose pathogenic variants are associated to IBD deficiency (OMIM #611283), a rare autosomal recessive disorder of valine catabolism. The c.822C>A was never previously described in a patient. Subsequent further analyses of Rf homeostasis showed reduced levels of flavins in plasma and altered FAD-dependent enzymatic activities in erythrocytes, as well as a significant reduction in the level of the plasma membrane Rf transporter 2 in erythrocytes. The observed Rf/flavin scarcity in this patient, possibly associated with a decreased ETF:QO efficiency might be responsible for the observed MADD-like phenotype. The patient's clinical picture improved after supplementation of Rf, l-carnitine, Coenzyme Q10, and also 3OH-butyrate. This report demonstrates that, even in the absence of genetic defects in genes involved in Rf homeostasis, further targeted molecular analysis may reveal secondary and possibly treatable biochemical alterations in this pattern.
PubMed: 35822092
DOI: 10.1002/jmd2.12292 -
Asia Pacific Journal of Clinical... 2022Poor nutritional status is a common finding in pulmonary tuberculosis (TB) patients with and without type 2 diabetes mellitus (T2DM), thiamin (VB-1) and riboflavin...
BACKGROUND AND OBJECTIVES
Poor nutritional status is a common finding in pulmonary tuberculosis (TB) patients with and without type 2 diabetes mellitus (T2DM), thiamin (VB-1) and riboflavin (VB-2) are coenzymes important for the activation of many enzymes involved in improving nutritional status. We aimed to investigate enzymatic activities and the associations between VB-1 and VB-2, and their relations to nutritional status in TB and TB+T2DM patients.
METHODS AND STUDY DESIGN
This was a cross-sectional study that prospectively enrolled TB 40 patients with or without T2DM respectively from the Chest Hospital of Qingdao and 76 healthy controls with similar age and gender distributions were recruited from the medical center of the affiliated hospital of Qingdao Medical College. The erythrocyte transketolase activation coefficient (ETKac, for VB-1 deficiency), the glutathione reductase activation coefficient (EGRac, for VB-2 deficiency), and metabolic enzyme activities were analyzed.
RESULTS
VB-1 and VB-2 deficiency rates were higher, and enzyme activities were lower in TB and TB+T2DM relative to control group. ETKac and EGRac were negatively correlated with enzyme activities, either with body mass index (BMI), while enzyme activities were positively associated with BMI.
CONCLUSIONS
VB-1 and VB-2 concentrations were lower in TB patients with or without T2DM relative to controls, with concomitant reductions in the activity levels of key metabolic enzymes. Significant correlations were observed between VB-1 and VB-2 concentrations and the activity of these metabolic enzymes, they all correlated with nutrition status. VB-1 and VB-2 concentrations may thus impact metabolic enzyme activity and thereby influence nutritional status.
Topics: China; Cross-Sectional Studies; Diabetes Mellitus, Type 2; Humans; Riboflavin; Riboflavin Deficiency; Thiamine; Tuberculosis, Pulmonary
PubMed: 35766561
DOI: 10.6133/apjcn.202206_31(2).0011 -
Biomedicines Jun 2022Riboflavin transporter deficiency (RTD) is a rare genetic disorder characterized by motor, sensory and cranial neuropathy. This childhood-onset neurodegenerative disease... (Review)
Review
Riboflavin transporter deficiency (RTD) is a rare genetic disorder characterized by motor, sensory and cranial neuropathy. This childhood-onset neurodegenerative disease is caused by biallelic pathogenic variants in either or genes, resulting in insufficient supply of riboflavin (vitamin B2) and consequent impairment of flavoprotein-dependent metabolic pathways. Current therapy, empirically based high-dose riboflavin supplementation, ameliorates the progression of the disease, even though response to treatment is variable and partial. Recent studies have highlighted concurrent pathogenic contribution of cellular energy dysmetabolism and cytoskeletal derangement. In this context, patient specific RTD models, based on induced pluripotent stem cell (iPSC) technology, have provided evidence of redox imbalance, involving mitochondrial and peroxisomal dysfunction. Such oxidative stress condition likely causes cytoskeletal perturbation, associated with impaired differentiation of RTD motor neurons. In this review, we discuss the most recent findings obtained using different RTD models. Relevantly, the integration of data from innovative iPSC-derived in vitro models and invertebrate in vivo models may provide essential information on RTD pathophysiology. Such novel insights are expected to suggest custom therapeutic strategies, especially for those patients unresponsive to high-dose riboflavin treatments.
PubMed: 35740351
DOI: 10.3390/biomedicines10061329 -
Redox Biology Aug 2022Ariboflavinosis is a pathological condition occurring as a result of riboflavin deficiency. This condition is treatable if detected early enough, but it lacks timely...
Ariboflavinosis is a pathological condition occurring as a result of riboflavin deficiency. This condition is treatable if detected early enough, but it lacks timely diagnosis. Critical symptoms of ariboflavinosis include neurological and visual manifestations, yet the effects of flavin deficiency on the retina are not well investigated. Here, using a diet induced mouse model of riboflavin deficiency, we provide the first evidence of how retinal function and metabolism are closely intertwined with riboflavin homeostasis. We find that diet induced riboflavin deficiency causes severe decreases in retinal function accompanied by structural changes in the neural retina and retinal pigment epithelium (RPE). This is preceded by increased signs of cellular oxidative stress and metabolic disorder, in particular dysregulation in lipid metabolism, which is essential for both photoreceptors and the RPE. Though many of these deleterious phenotypes can be ameliorated by riboflavin supplementation, our data suggests that some patients may continue to suffer from multiple pathologies at later ages. These studies provide an essential cellular and mechanistic foundation linking defects in cellular flavin levels with the manifestation of functional deficiencies in the visual system and paves the way for a more in-depth understanding of the cellular consequences of ariboflavinosis.
Topics: Animals; Homeostasis; Mice; Retina; Retinal Pigment Epithelium; Riboflavin; Riboflavin Deficiency
PubMed: 35738087
DOI: 10.1016/j.redox.2022.102375 -
Balkan Medical Journal Jul 2022To evaluate the clinical, pathological, and genetic features of patients with riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency (RR-MADD).
AIMS
To evaluate the clinical, pathological, and genetic features of patients with riboflavin-responsive multiple acyl-CoA dehydrogenase deficiency (RR-MADD).
METHODS
Thirty-one patients with RR-MADD admitted to our hospital from January 2005 to November 2020 were enrolled, and their clinical data were collected. Pathological characteristics of the muscle tissue and possible pathogenic gene mutations were analyzed.
RESULTS
The most common clinical features in all patients were symmetrical proximal muscle weakness. Laboratory examination revealed elevated levels of creatine kinase, homocysteine, and uric acid, acylcarnitines, and organic acid. The muscle biopsy revealed typical pathological changes like lipid deposition. Genetic analysis identified ETFDH mutations in 29 patients, among which one had homozygotes, 19 had compound heterozygotes, 7 had heterozygous mutations, and 2 had heterozygous mutations of both ETFDH and ETFA. Two patients had no pathogenic gene mutations. All patients were treated with riboflavin, and their symptoms improved, which was consistent with the diagnosis of RR-MADD.
CONCLUSION
The clinical manifestations and genetic test results of patients with RR-MADD are heterogeneous. Therefore, a comprehensive analysis of clinical, pathological, and genetic testing is essential for the early diagnosis of RR-MADD.
Topics: Electron-Transferring Flavoproteins; Humans; Iron-Sulfur Proteins; Multiple Acyl Coenzyme A Dehydrogenase Deficiency; Oxidoreductases Acting on CH-NH Group Donors; Riboflavin
PubMed: 35734957
DOI: 10.4274/balkanmedj.galenos.2022.2022-1-127 -
Cellular and Molecular Life Sciences :... Jun 2022The SLC25A32 dysfunction is associated with neural tube defects (NTDs) and exercise intolerance, but very little is known about disease-specific mechanisms due to a...
The SLC25A32 dysfunction is associated with neural tube defects (NTDs) and exercise intolerance, but very little is known about disease-specific mechanisms due to a paucity of animal models. Here, we generated homozygous (Slc25a32 and Slc25a32) and compound heterozygous (Slc25a32) knock-in mice by mimicking the missense mutations identified from our patient. A homozygous knock-out (Slc25a32) mouse was also generated. The Slc25a32 and Slc25a32 mice presented with mild motor impairment and recapitulated the biochemical disturbances of the patient. While Slc25a32 mice die in utero with NTDs. None of the Slc25a32 mutations hindered the mitochondrial uptake of folate. Instead, the mitochondrial uptake of flavin adenine dinucleotide (FAD) was specifically blocked by Slc25a32, Slc25a32, and Slc25a32 mutations. A positive correlation between SLC25A32 dysfunction and flavoenzyme deficiency was observed. Besides the flavoenzymes involved in fatty acid β-oxidation and amino acid metabolism being impaired, Slc25a32 embryos also had a subunit of glycine cleavage system-dihydrolipoamide dehydrogenase damaged, resulting in glycine accumulation and glycine derived-formate reduction, which further disturbed folate-mediated one-carbon metabolism, leading to 5-methyltetrahydrofolate shortage and other folate intermediates accumulation. Maternal formate supplementation increased the 5-methyltetrahydrofolate levels and ameliorated the NTDs in Slc25a32 embryos. The Slc25a32 and Slc25a32 mice had no glycine accumulation, but had another formate donor-dimethylglycine accumulated and formate deficiency. Meanwhile, they suffered from the absence of all folate intermediates in mitochondria. Formate supplementation increased the folate amounts, but this effect was not restricted to the Slc25a32 mutant mice only. In summary, we established novel animal models, which enabled us to understand the function of SLC25A32 better and to elucidate the role of SLC25A32 dysfunction in human disease development and progression.
Topics: Animals; Humans; Mice; Carbon; Flavin-Adenine Dinucleotide; Folic Acid; Formates; Glycine; Mitochondria; Neural Tube Defects
PubMed: 35727412
DOI: 10.1007/s00018-022-04404-0 -
Frontiers in Microbiology 2022Influenza is a serious respiratory disease that continues to threaten global health. Mucosa-associated invariant T (MAIT) cells use T-cell receptors (TCRs) that...
Influenza is a serious respiratory disease that continues to threaten global health. Mucosa-associated invariant T (MAIT) cells use T-cell receptors (TCRs) that recognize microbial riboflavin derived intermediates presented by the major histocompatibility complex (MHC) class I-like protein MR1. Riboflavin synthesis is broadly conserved, but the roles or mechanisms of riboflavin in MR1 mouse influenza infection are not well understood. In our study, immunofluorescence techniques were applied to analyze the number and distribution of viruses in lung tissue. The amount of cytokine expression was assessed by flow cytometry (FCM), ELISA, and qPCR. The changes in the fecal flora of mice were evaluated based on amplicon sequencing of the 16S V3-V4 region. Our study showed that MAIT cell deficiency increased mortality and that riboflavin altered these effects in microbiota-depleted mice. The oral administration of riboflavin inhibited IL-1β, IL-17A, and IL-18 production but significantly increased the expression of IFN-γ, TNF-α, CCL2, CCL3, and CCL4 in a mouse model. The analysis of the mouse flora revealed that riboflavin treatment significantly increased the relative abundance of and ( < 0.05) and decreased that of . In contrast, MR1 mice exhibited a concentrated aggregation of ( < 0.01), which indicated that MAIT cell deficiency reduced the diversity of the bacterial population. Our results define the functions of MAIT cells and riboflavin in resistance to influenza virus and suggest a potential role for riboflavin in enhancing MAIT cell immunity and the intestinal flora diversity. Gut populations can be expanded to enhance host resistance to influenza, and the results indicate novel interactions among viruses, MAIT cells, and the gut microbiota.
PubMed: 35722312
DOI: 10.3389/fmicb.2022.916580 -
Molecules (Basel, Switzerland) May 2022Mitochondrial diseases (MDs) may result from mutations affecting nuclear or mitochondrial genes, encoding mitochondrial proteins, or non-protein-coding mitochondrial... (Review)
Review
Mitochondrial diseases (MDs) may result from mutations affecting nuclear or mitochondrial genes, encoding mitochondrial proteins, or non-protein-coding mitochondrial RNA. Despite the great variability of affected genes, in the most severe cases, a neuromuscular and neurodegenerative phenotype is observed, and no specific therapy exists for a complete recovery from the disease. The most used treatments are symptomatic and based on the administration of antioxidant cocktails combined with antiepileptic/antipsychotic drugs and supportive therapy for multiorgan involvement. Nevertheless, the real utility of antioxidant cocktail treatments for patients affected by MDs still needs to be scientifically demonstrated. Unfortunately, clinical trials for antioxidant therapies using α-tocopherol, ascorbate, glutathione, riboflavin, niacin, acetyl-carnitine and coenzyme Q have met a limited success. Indeed, it would be expected that the employed antioxidants can only be effective if they are able to target the specific mechanism, i.e., involving the central and peripheral nervous system, responsible for the clinical manifestations of the disease. Noteworthily, very often the phenotypes characterizing MD patients are associated with mutations in proteins whose function does not depend on specific cofactors. Conversely, the administration of the antioxidant cocktails might determine the suppression of endogenous oxidants resulting in deleterious effects on cell viability and/or toxicity for patients. In order to avoid toxicity effects and before administering the antioxidant therapy, it might be useful to ascertain the blood serum levels of antioxidants and cofactors to be administered in MD patients. It would be also worthwhile to check the localization of mutations affecting proteins whose function should depend (less or more directly) on the cofactors to be administered, for estimating the real need and predicting the success of the proposed cofactor/antioxidant-based therapy.
Topics: Anticonvulsants; Antioxidants; DNA, Mitochondrial; Humans; Mitochondria; Mitochondrial Diseases; Mitochondrial Proteins; Precision Medicine
PubMed: 35684429
DOI: 10.3390/molecules27113494