Aging-induced short-chain acyl-CoA dehydrogenase promotes age-related hepatic steatosis by suppressing lipophagy.

Hepatic steatosis, the first step in the development of nonalcoholic fatty liver disease (NAFLD), is frequently observed in the aging population. However, the underlying molecular mechanism remains largely unknown. In this study, we first employed GSEA enrichment analysis to identify short-chain acyl-CoA dehydrogenase (SCAD), which participates in the mitochondrial ß-oxidation of fatty acids and may be associated with hepatic steatosis in elderly individuals. Subsequently, we examined SCAD expression and hepatic triglyceride content in various aged humans and mice and found that triglycerides were markedly increased and that SCAD was upregulated in aged livers. Our further evidence in SCAD-ablated mice suggested that SCAD deletion was able to slow liver aging and ameliorate aging-associated fatty liver. Examination of the molecular pathways by which the deletion of SCAD attenuates steatosis revealed that the autophagic degradation of lipid droplets, which was not detected in elderly wild-type mice, was maintained in SCAD-deficient old mice. This was due to the decrease in the production of acetyl-coenzyme A (acetyl-CoA), which is abundant in the livers of old wild-type mice. In conclusion, our findings demonstrate that the suppression of SCAD may prevent age-associated hepatic steatosis by promoting lipophagy and that SCAD could be a promising therapeutic target for liver aging and associated steatosis.

Hepatocyte-secreted FAM3D ameliorates hepatic steatosis by activating FPR1-hnRNP U-GR-SCAD pathway to enhance lipid oxidation.

Nonalcoholic fatty liver disease (NAFLD) is the most common chronic liver disease worldwide; however, the underlying mechanisms remain poorly understood. FAM3D is a member of the FAM3 family; however, its role in hepatic glycolipid metabolism remains unknown. Serum FAM3D levels are positively correlated with fasting blood glucose levels in patients with diabetes. Hepatocytes express and secrete FAM3D, and its expression is increased in steatotic human and mouse livers. Hepatic FAM3D overexpression ameliorated hyperglycemia and steatosis in obese mice, whereas FAM3D-deficient mice exhibited exaggerated hyperglycemia and steatosis after high-fat diet (HFD)-feeding. In cultured hepatocytes, FAM3D overexpression or recombinant FAM3D protein (rFAM3D) treatment reduced gluconeogenesis and lipid deposition, which were blocked by anti-FAM3D antibodies or inhibition of its receptor, formyl peptide receptor 1 (FPR1). FPR1 overexpression suppressed gluconeogenesis and reduced lipid deposition in wild hepatocytes but not in FAM3D-deficient hepatocytes. The addition of rFAM3D restored FPR1's inhibitory effects on gluconeogenesis and lipid deposition in FAM3D-deficient hepatocytes. Hepatic FPR1 overexpression ameliorated hyperglycemia and steatosis in obese mice. RNA sequencing and DNA pull-down revealed that the FAM3D-FPR1 axis upregulated the expression of heterogeneous nuclear ribonucleoprotein U (hnRNP U), which recruits the glucocorticoid receptor (GR) to the promoter region of the short-chain acyl-CoA dehydrogenase (SCAD) gene, promoting its transcription to enhance lipid oxidation. Moreover, FAM3D-FPR1 axis also activates calmodulin-Akt pathway to suppress gluconeogenesis in hepatocytes. In conclusion, hepatocyte-secreted FAM3D activated the FPR1-hnRNP U-GR-SCAD pathway to enhance lipid oxidation in hepatocytes. Under obesity conditions, increased hepatic FAM3D expression is a compensatory mechanism against dysregulated glucose and lipid metabolism.

Riboflavin protects against heart failure via SCAD-dependent DJ-1-Keap1-Nrf2 signalling pathway.

BACKGROUND AND PURPOSE: Our recent studies have shown that flavin adenine dinucleotide (FAD) exerts cardiovascular protective effects by supplementing short-chain acyl-CoA dehydrogenase (SCAD). The current study aimed to elucidate whether riboflavin (the precursor of FAD) could improve heart failure via activating SCAD and the DJ-1-Keap1-Nrf2 signalling pathway. EXPERIMENTAL APPROACH: Riboflavin treatment was given to the mouse transverse aortic constriction (TAC)-induced heart failure model. Cardiac structure and function, energy metabolism and apoptosis index were assessed, and relevant signalling proteins were analysed. The mechanisms underlying the cardioprotection by riboflavin were analysed in the cell apoptosis model induced by tert-butyl hydroperoxide (tBHP). KEY RESULTS: In vivo, riboflavin ameliorated myocardial fibrosis and energy metabolism, improved cardiac dysfunction and inhibited oxidative stress and cardiomyocyte apoptosis in TAC-induced heart failure. In vitro, riboflavin ameliorated cell apoptosis in H9C2 cardiomyocytes by decreasing reactive oxygen species (ROS). At the molecular level, riboflavin significantly restored FAD content, SCAD expression and enzymatic activity, activated DJ-1 and inhibited the Keap1-Nrf2/HO1 signalling pathway in vivo and in vitro. SCAD knockdown exaggerated the tBHP-induced DJ-1 decrease and Keap1-Nrf2/HO1 signalling pathway activation in H9C2 cardiomyocytes. The knockdown of SCAD abolished the anti-apoptotic effects of riboflavin on H9C2 cardiomyocytes. DJ-1 knockdown hindered SCAD overexpression anti-apoptotic effects and regulation on Keap1-Nrf2/HO1 signalling pathway in H9C2 cardiomyocytes. CONCLUSIONS AND IMPLICATIONS: Riboflavin exerts cardioprotective effects on heart failure by improving oxidative stress and cardiomyocyte apoptosis via FAD to stimulate SCAD and then activates the DJ-1-Keap1-Nrf2 signalling pathway.

Riboflavin ameliorates pathological cardiac hypertrophy and fibrosis through the activation of short-chain acyl-CoA dehydrogenase.

Short-chain acyl-CoA dehydrogenase (SCAD), the rate-limiting enzyme for fatty acid ß-oxidation, has a negative regulatory effect on pathological cardiac hypertrophy and fibrosis. FAD, a coenzyme of SCAD, participates in the electron transfer of SCAD-catalyzed fatty acid ß-oxidation, which plays a crucial role in maintaining the balance of myocardial energy metabolism. Insufficient riboflavin intake can lead to symptoms similar to short-chain acyl-CoA dehydrogenase (SCAD) deficiency or flavin adenine dinucleotide (FAD) gene abnormality, which can be alleviated by riboflavin supplementation. However, whether riboflavin can inhibit pathological cardiac hypertrophy and fibrosis remains unclear. Therefore, we observed the effect of riboflavin on pathological cardiac hypertrophy and fibrosis. In vitro experiments, riboflavin increased SCAD expression and the content of ATP, decreased the free fatty acids content and improved PE-induced cardiomyocytes hypertrophy and AngⅡ-induced cardiac fibroblasts proliferation by increasing the content of FAD, which were attenuated by knocking down the expression of SCAD using small interfering RNA. In vivo experiments, riboflavin significantly increased the expression of SCAD and the energy metabolism of the heart to improve TAC induced pathological myocardial hypertrophy and fibrosis in mice. The results demonstrate that riboflavin improves pathological cardiac hypertrophy and fibrosis by increasing the content of FAD to activate SCAD, which may be a new strategy for treating pathological cardiac hypertrophy and fibrosis.

Diverse and unselected adults with clinically relevant ACADS variants lack evidence of metabolic disease.

INTRODUCTION: The clinical significance of Short-chain acyl CoA dehydrogenase deficiency (SCADD), caused by biallelic variation in the ACADS gene, is contested. Clinically ascertained individuals have a range of reported metabolic and physical symptoms. Conversely, individuals identified through newborn screening remain overwhelmingly asymptomatic. Two common ACADS variants, c.511C > T (p.Arg171Trp) and c.625G > A (p.Gly209Ser) are known to reduce enzymatic activity with undetermined clinical correlate. We applied a genome-first approach to evaluate the prevalence and clinical consequences of ACADS variants in an ancestrally diverse and unselected patient population. MATERIAL AND METHODS: We used exome sequence data linked to electronic health records (EHRs) to identify clinically relevant ACADS variants, and estimate their prevalence and clinical implications in 27,447 ancestrally diverse and unrelated adults from the BioMe Biobank in New York, NY. We extracted International Classification of Diseases, ninth (ICD-9) and tenth (ICD-10) revision codes corresponding to eight SCADD-associated phenotypes relevant to adults from participants' EHRs. Phenotypes included intellectual disability, behavioral disorders with onset in childhood, epilepsy or seizure disorders, hypoglycemia, muscle weakness, metabolic acidosis, fatty liver, and a diagnosis of SCADD or disorder of fatty acid oxidation. We performed manual chart reviews for individuals homozygous for rare pathogenic variants. Multivariate logistic regression was used to determine the association between clinically relevant ACADS variants and phenotypes of interest. RESULTS: 1 in 10,000 BioMe participants were homozygous for rare pathogenic variants (PVs) in ACADS, 1 in 20 were homozygous or presumed compound heterozygous for common variants (CVs), and 1 in 300 harbored both a PV and a CV. Of the 2035 variant positive individuals, none had a documented diagnosis of SCADD. We identified five PV/PV positive individuals, none of whom had evidence of symptomatic SCADD on manual chart review. CV/CV positive and CV/PV positive individuals did not have increased odds of any of the eight ACADS phenotypes evaluated compared to variant negative individuals (OR for CV/CV 0.99, 95% CI 0.86-1.1, p = .88; OR for CV/PV OR 1.49, 95% CI 0.87-2.6, p = .15). CONCLUSIONS: The prevalence of clinically relevant ACADS variants in an unselected population was higher than previously reported SCADD prevalence of 1 in 35,000 in the United States. Clinically relevant variants in ACADS were not associated with evidence of metabolic disease in a large and ancestrally diverse adult population. These findings support the assertion that SCADD is more likely a biochemical entity without clinical correlate, in particular when caused by one or more common variants.

Astragaloside IV inhibits Ang H-induced cell proliferation and collagen expression in cardiac fibroblasts by activating short-chain acyl-CoA dehydrogenase / 中国药理学通报

Aim To explore the effect of astragaloside IV (AS-IV) on cell proliferation and collagen expression in cardiac fibroblasts (CFs) of rats induced with angiotensin II (Ang II) and its mechanism. Methods CFs were pretreated with short-chain acyl-CoA dehydrogenase (SCAD) siRNA1186 for 12 h and then co-treated with Ang TJ and AS-IV for 36 h. The expressions of SCAD, α-SMA, collagen I and collagen III in CFs were detected by Western blot. mRNA expression levels of SCAD, a-SMA, collagen I and collagen III in CFs were detected by quantitative real-time PCR. The SCAD enzymatic activity, the content of ATP, hydroxyproline and free fatty acid were measured by detection kits. Results The expression of α-SMA, collagen I and collagen III were up-regulated (all P < 0. 01) in CFs induced by Ang II compared with the control cells, and the expression and enzymatic activity of SCAD significantly decreased (P < 0. 01, P< 0. 05). The content of ATP decreased (P < 0.01), and the content of hydroxyproline and free fatty acids increased (all P < 0.01). Compared with Ang II group, SCAD expression and enzymatic activity, and ATP content were significantly increased (all P < 0.01) in Ang II + AS-TV group, but the content of hydroxyproline and free fatty acids, and the expression of α-SMA, collagen I and collagen III significantly decreased (all P < 0.01). However, compared with the Ang II + NC group, there was no significant difference in all indices in the Ang II + SiRNA1186 + AS-TV group. The protective effect of AS-TV on Ang II -induced cell proliferation and collagen expression in CFs was eliminated by the interference of SCAD SiRNA1186. Conclusions AS-IV may inhibit Ang II-induced cell proliferation and collagen expression in CFs by activating SCAD.

Clinical characteristics and related gene mutations of infants with short-chain acyl-CoA dehydrogenase deficiency by neonatal screening in Beijing.

OBJECTIVE: To investigate the clinical characteristics of infants with short-chain acyl-CoA dehydrogenase deficiency (SCADD) and related gene mutations in Beijing. METHODS: The acylcarnitine levels in the blood samples of 100 603 neonates in Beijing during August 2014 and March 2022 were measured by tandem mass spectrometry (MS/MS). The suspected SCADD neonates were rechecked by MS/MS, urine gas chromatography-mass spectrometry (GC/MS) and next-generation sequencing (NGS) for diagnosis. The clinical, biochemical and gene mutation characteristics of infants with SCADD were analyzed; the growth and intellectual development of these patients were observed regularly. RESULTS: Among 100 603 live births, the elevated C4 concentration or elevated C4/C3 ratio were detected in the initial screening from 196 neonates, and 131 were recalled. Five cases of SCADD were diagnosed with an incidence rate of 4.97/100 000 (1/20 121). There was no significant abnormality in clinical manifestations, however, the blood butyrylcarnitine (C4) level and the ratio of C4 to propionylcarnitine (C3) were raised in all diagnosed cases. Urinary organic acids were analyzed in 4 cases, all of whom had increased ethyl malonate acid levels. Seven mutations were detected in the ACADS gene, all of which were known missense mutations. One patient had homozygous mutation, and the others showed compound heterozygous mutations. No clinical symptoms were observed, and the physical and intellectual development was normal in all patients at a median age of 33 (4-40) months during follow-up. CONCLUSIONS: The incidence rate of SCADD was 1/20 121 in Beijing. Neonates with early diagnosis and without clinical symptoms usually have good prognosis.

Quantitation of Butyrylcarnitine, Isobutyrylcarnitine, and Glutarylcarnitine in Urine Using Ultra-Performance Liquid Chromatography-Tandem Mass Spectrometry (UPLC-MS/MS).

Acylcarnitines are formed when an acyl group is transferred from coenzyme A to a molecule of L-carnitine. In organic acidemias, and in fatty acid oxidation disorders, specific acylcarnitine species accumulate in a pattern that is characteristic for each disease. For this reason, acylcarnitine analysis is widely used for screening and diagnosis of inherited disorders of metabolism. The most common method for acylcarnitine analysis uses flow injection tandem mass spectrometry. Flow injection analysis allows for high throughput, however, does not provide separation of isomeric and isobaric compounds. Among the acylcarnitine species which can be affected by the presence of isomeric/isobaric compounds, C4-carnitine and C5DC-carnitine are probably the ones encountered most often. The method presented here is performed on urine and utilizes butanolic HCL to derivatize acylcarnitines, ultra-performance liquid chromatography to resolve C4- and C5-DC isomers and isobars, and quantitation of these species using multiple-reaction monitoring (MRM).

Multiplexed LC-MS/MS analysis of methylsuccinic acid, ethylmalonic acid, and glutaric acid in plasma and urine.

Low molecular-mass aliphatic carboxylic acids are critically important for intermediate metabolism and may serve as important biomarkers for metabolic homeostasis. Here in, we focused on multiplexed method development of aliphatic carboxylic analytes, including methylsuccinic acid (MSA), ethylmalonic acid (EMA), and glutaric acid (GA). Also assessed was their utility in a population's health as well as metabolic disease screening in both plasma and urine matrices. MSA, EMA, and GA are constitutional isomers of dicarboxylic acid with high polarity and poor ionization efficiency, resulting in such challenges as poor signal intensity and retention, particularly in reversed-phase liquid chromatography with electrospray mass spectrometry (RP-LC-ESI-MS/MS). Derivatization using n-butanol was performed in the sample preparation to enhance the signal intensity accompanied with a positive charge from ionization in complicated biomatrices as well as to improve the separation of these isomers with optimal retention. Fit-for-purpose method validation results demonstrated quantitative ranges for MSA/EMA/GA from 5/10/20 ng/mL to 400 ng/mL in plasma analysis, and 100/200/100 ng/mL to 5000/10000/5000 ng/mL in urine analysis. This validated method demonstrates future utility when exploring population health analysis and biomarker development in metabolic diseases.

Riboflavin inhibits heart failure in mice by activating SCAD / 中国药理学通报

Aim To explore the effeet of riboflavin on the establishment of pressure overload-induced heart failure model in mice by thoracic aortie constrietion (TAC ) and its preventive mechanism.Methods Eight-week-old SPF C57BL/6J mice were seleeted and divided into four groups; Sham group.Sham + ribofla¬vin group, TAC group and TAC + riboflavin group.A mouse heart failure model was constructed in the TAC group.The miee in the TAC + riboflavin group were given riboflavin by gavage one week before and eight weeks after the operation.The cardiac ultrasound inde¬xes, the changes of cardiac morphology and mitochon¬drial function indexes, the expression of apoptosis pro¬teins, ATP content, SCAD mRNA and protein expres¬sion, enzyme activity and flavin adenine dinucleotide (FAD) content in myocardial tissues were detected.Hie free fatty acid content in serum and myocardial tis¬sues were also detected.Results Compared with the sham group, the cardiac function indexes of the mice in the TAC group decreased, anrl typical heart failure occurred.Moreover, the expression of SCAD, enzyme activity, ATP and FAD content in the myocardium sig-nificantly decreased, and the free fatty acid content in myocardium and serum significantly increased.Com¬pared with the TAC group, after riboflavin treatment, the cardiac function of mice in TAC + Riboflavin group was significantly improved.In addition, ATP content, SCAD expression, enzyme activity and FAD content in myocardium all significantly increased, and free fatty acid content in myocardium and serum markedly de¬creased.Conclusions Riboflavin may improve myo-cardial energy metabolism by increasing FAD content and activating SCAD, thereby inhibiting pressure over¬load-induced heart failure in mice.

Variants in the ethylmalonyl-CoA decarboxylase (ECHDC1) gene: a novel player in ethylmalonic aciduria?

Ethylmalonic acid (EMA) is a major and potentially cytotoxic metabolite associated with short-chain acyl-CoA dehydrogenase (SCAD) deficiency, a condition whose status as a disease is uncertain. Unexplained high EMA is observed in some individuals with complex neurological symptoms, who carry the SCAD gene (ACADS) variants, c.625G>A and c.511C>T. The variants have a high allele frequency in the general population, but are significantly overrepresented in individuals with elevated EMA. This has led to the idea that these variants need to be associated with variants in other genes to cause hyperexcretion of ethylmalonic acid and possibly a diseased state. Ethylmalonyl-CoA decarboxylase (ECHDC1) has been described and characterized as an EMA metabolite repair enzyme, however, its clinical relevance has never been investigated. In this study, we sequenced the ECHDC1 gene (ECHDC1) in 82 individuals, who were reported with unexplained high EMA levels due to the presence of the common ACADS variants only. Three individuals with ACADS c.625G>A variants were found to be heterozygous for ECHDC1 loss-of-function variants. Knockdown experiments of ECHDC1, in healthy human cells with different ACADS c.625G>A genotypes, showed that ECHDC1 haploinsufficiency and homozygosity for the ACADS c.625G>A variant had a synergistic effect on cellular EMA excretion. This study reports the first cases of ECHDC1 gene defects in humans and suggests that ECHDC1 may be involved in elevated EMA excretion in only a small group of individuals with the common ACADS variants. However, a direct link between ECHDC1/ACADS deficiency, EMA and disease could not be proven.

Unexpected elevation in valproic acid concentration and agranulocytosis in a patient with short-chain acyl-CoA dehydrogenase deficiency.

BACKGROUND: Short-chain acyl-CoA dehydrogenase (SCAD) deficiency is an autosomal recessive metabolic disorder or condition of fatty acid ß-oxidation, caused by mutations in the gene encoding SCAD (ACADS). We report an infant with SCAD deficiency who unexpectedly exhibited an extremely high blood concentration of valproic acid (VPA) and agranulocytosis. CASE REPORT: An 8-month-old girl was diagnosed with West syndrome (infantile spasms), and VPA was administered at the standard level of 25 mg/kg/day. However, the blood concentration of VPA rose unexpectedly to 230 µg/mL (two- to three-fold higher than the expected value), and continued to remain relatively high even after the dosage was reduced (7 mg/kg/day, blood concentration of 88 µg/mL). Furthermore, she presented with a high-grade fever with agranulocytosis (neutrophil 231/µL). The abnormal pharmacokinetics and toxicity of VPA raised the suspicion of possible inborn errors of metabolism in the fatty acid ß-oxidation pathway. Blood tandem mass spectrometry revealed a transient elevation of C4, and urine gas chromatography-mass spectrometry revealed a continuous elevation of ethylmalonate. Finally, gene analysis revealed compound heterozygous mutations, c.625G > A (p.G209S) and c.1031A > G (p.E344G), in ACADS. CONCLUSION: VPA should be avoided if a patient is suspected to have inborn errors of ß-oxidation including SCAD deficiency.

Neonatal Screening on Tandem Mass Spectrometry as a Powerful Tool for the Reassessment of the Prevalence of Underestimated Diseases in Newborns and Their Family Members: A Focus on Short Chain Acyl-CoA Dehydrogenase Deficiency.

Early detection of disabling diseases, prior to clinical manifestations, is the primary goal of newborn screening (NS). Indeed, the required number of core and secondary conditions selected for screening panels is increasing in many countries. Furthermore, newborn screening can lead to diagnosis of maternal diseases such as vitamin B12 deficiency or 3-MethylcrotonylCoA-carboxylase deficiency (3MCC). NS became mandatory in Sicily in December 2017. Here we report NS data collected between December 2017 and April 2020. Our results show that tandem mass spectrometry is a powerful tool for discovery of underestimated disease in newborns and their family members. Our panel included short chain acyl-CoA dehydrogenase deficiency (SCADD). Here, we report that results of our investigation led to reassessment of SCADD prevalence in our population. The infant and adult patients diagnosed in our study had previously not shown overt symptoms.

Ethylmalonic encephalopathy: Clinical course and therapy response in an uncommon mild case with a severe ETHE1 mutation.

Ethylmalonic encephalopathy (EE) is a rare metabolic disorder caused by dysfunction of ETHE1 protein, a mitochondrial dioxygenase involved in hydrogen sulfide (H2S) detoxification. EE is usually a fatal disease with a severe clinical course mainly associated with developmental delay and regression, recurrent petechiae, orthostatic acrocyanosis, and chronic diarrhoea. Treatment includes antioxidants, antibiotics that lower H2S levels and antispastic medications, which are not curative. The mutations causing absence of the ETHE1 protein, as is the case for the described patient, usually entail a severe fatal phenotype. Although there are rare reported cases with mild clinical findings, the mechanism leading to these milder cases is also unclear. Here, we describe an 11-year-old boy with an ETHE1 gene mutation who has no neurocognitive impairment but chronic diarrhoea, which is controlled by oral medical treatment, and progressive spastic paraparesis that responded to Achilles tendon lengthening.

Diagnosis, genetic characterization and clinical follow up of mitochondrial fatty acid oxidation disorders in the new era of expanded newborn screening: A single centre experience.

INTRODUCTION: Mitochondrial fatty acid oxidation disorders (FAODs) are a heterogeneous group of hereditary autosomal recessive diseases included in newborn screening (NBS) program in Italy. The aim of this study was to analyse FAODs cases, identified either clinically or by NBS,for clinical and genetic characterization and to evaluate a five years' experience of NBS, in the attempt to figure out the complexity of genotype-phenotype correlation and to confirm the clinical impact of NBS in our centre experience. MATERIALS AND METHODS: We analysed FAODs patients diagnosed either by NBS or clinically, followed since February 2014 to April 2019 at the Regional Screening Centre and Inherited Metabolic Diseases Unit of Verona. Diagnosis was confirmed by plasma acylcarnitines, urinary organic acids, enzymatic and genetic testing. For not clear genotypes due to the presence of variants of uncertain significance, in silico predictive tools have been used as well as enzymatic activity assays. Patients underwent clinical, nutritional and biochemical follow up. RESULTS: We diagnosed 30 patients with FAODs. 20 by NBS: 3 CUD, 6 SCADD, 5 MCADD, 4 VLCADD, 2 MADD. Overall incidence of FAODs diagnosed by NBS was 1:4316 newborns. No one reported complications during the follow up period. 10 patients were diagnosed clinically: 2 CUD, 2 CPT2D, 1 VLCADD, 5 MADD. Mean age at diagnosis was 29.3 years. Within this group, complications or symptoms were reported at diagnosis, but not during follow-up. 12 mutations not previously reported in literature were found, all predicted as pathogenic or likely pathogenic. DISCUSSION AND CONCLUSIONS: Our study highlighted the great phenotypic variability and molecular heterogeneity of FAODs and confirmed the importance of a tailored follow up and treatment. Despite the short duration of follow up, early identification by NBS prevented diseases related complications and resulted in normal growth and psycho-motor development as well.

Genomic Analysis of Historical Cases with Positive Newborn Screens for Short-Chain Acyl-CoA Dehydrogenase Deficiency Shows That a Validated Second-Tier Biochemical Test Can Replace Future Sequencing.

Short-chain acyl-CoA dehydrogenase deficiency (SCADD) is a rare autosomal recessive disorder of ß-oxidation caused by pathogenic variants in the ACADS gene. Analyte testing for SCADD in blood and urine, including newborn screening (NBS) using tandem mass spectrometry (MS/MS) on dried blood spots (DBSs), is complicated by the presence of two relatively common ACADS variants (c.625G>A and c.511C>T). Individuals homozygous for these variants or compound heterozygous do not have clinical disease but do have reduced short-chain acyl-CoA dehydrogenase (SCAD) activity, resulting in elevated blood and urine metabolites. As part of a larger study of the potential role of exome sequencing in NBS in California, we reviewed ACADS sequence and MS/MS data from DBSs from a cohort of 74 patients identified to have SCADD. Of this cohort, approximately 60% had one or more of the common variants and did not have the two rare variants, and thus would need no further testing. Retrospective analysis of ethylmalonic acid, glutaric acid, 2-hydroxyglutaric acid, 3-hydroxyglutaric acid, and methylsuccinic acid demonstrated that second-tier testing applied before the release of the newborn screening result could reduce referrals by over 50% and improve the positive predictive value for SCADD to above 75%.

Flavin adenine dinucleotide ameliorates hypertensive vascular remodeling via activating short chain acyl-CoA dehydrogenase.

AIMS: Flavin adenine dinucleotide (FAD), participates in fatty acid ß oxidation as a cofactor, which has been confirmed to enhance SCAD activity and expression. However, the role of FAD on hypertensive vascular remodeling is unclear. In this study, we investigated the underlying mechanisms of FAD on vascular remodeling and endothelial homeostasis. MAIN METHODS: Morphological examination of vascular remodeling were analyzed with hematoxylin and eosin (HE) staining, Verhoeff's Van Gieson (EVG) staing, Dihydroethidium (DHE) staining and Sirius red staining. HUVECs apoptotic rate was detected by flow cytometry and HUVECs reactive oxygen species (ROS) was detected by DHE-probe. Enzymatic reactions were used to detect SCAD enzyme activity. The protein level was detected by Western Blots, the mRNA level was detected by quantitative real-time PCR. KEY FINDINGS: In vivo experiments, FAD significantly decreased blood pressure and ameliorated vascular remodeling by increasing SCAD expression, Nitric Oxide (NO) production and reducing ROS production. In vitro experiments, FAD protected against the tBHP induced injury in HUVEC, by increasing the activity of SCAD, increasing the elimination of free fatty acid (FFA), scavenging ROS, reducing apoptotic rate, thereby improving endothelial cell function. SIGNIFICANCE: FAD has a new possibility for preventing and treating hypertensive vascular remodeling.

Newborn screening and genetic characteristics of patients with short- and very long-chain acyl-CoA dehydrogenase deficiencies.

BACKGROUND AND AIMS: Acyl-CoA dehydrogenase deficiencies are a group of mitochondrial fatty-acid oxidation disorders rarely reported in mainland China. We assessed the biochemical and genetic characteristics of patients with short- and very-long-chain-acyl-CoA dehydrogenase deficiencies (SCADD/VLCADD) discovered through newborn screening. MATERIALS AND METHODS: We investigated the effects of genetic variations on protein function using in silico prediction and structural modelling. RESULTS: Of 364,545 screened newborns, four were diagnosed with SCADD and four with VLCADD. SCADD and VLCADD incidences in our population were 1:91,136. All patients exhibited elevated C4 or C14:1 levels. Three SCADD patients had increased urinary ethylmalonic acid concentrations. Six ACADS and eight ACADVL variants were identified, with no hotspot variants, and five were unreported, including four missense variants and one splice site variant. ACADVL c.1434 + 2 T > C is a splice site variant that could affect splicing, leading to exon 14 skipping. In silico tools predicted the missense variants as pathogenic. Structural modelling confirmed that the missense variants may affect quaternary structures, causing protein instability. CONCLUSIONS: Our findings expanded the ACADS and ACADVL mutational spectra. The combination of in silico prediction and structural modelling can improve our understanding of the pathogenicity of unreported genetic variants, providing an explanation for variant assessment.

Flavine adenine dinucleotide inhibits pathological cardiac hypertrophy and fibrosis through activating short chain acyl-CoA dehydrogenase.

Short-chain acyl-CoA dehydrogenase (SCAD), the rate-limiting enzyme for fatty acid ß-oxidation, has a negative regulatory effect on pathological cardiac hypertrophy and fibrosis. Furthermore, flavin adenine dinucleotide (FAD) can enhance the expression and enzyme activity of SCAD. However, whether FAD can inhibit pathological cardiac hypertrophy and fibrosis remains unclear. Therefore, we observed the effect of FAD on pathological cardiac hypertrophy and fibrosis. FAD significantly inhibited PE-induced cardiomyocyte hypertrophy and AngII-induced cardiac fibroblast proliferation. In addition, FAD ameliorated pathological cardiac hypertrophy and fibrosis in SHR. FAD significantly increased the expression and enzyme activity of SCAD. Meanwhile, ATP content was increased, the content of free fatty acids and reactive oxygen species were decreased by FAD in vivo and in vitro. In addition, molecular dynamics simulations were also used to provide insights into the structural stability and dynamic behavior of SCAD. The results demonstrated that FAD may play an important structural role on the SCAD dimer stability and maintenance of substrate catalytic pocket to increase the expression and enzyme activity of SCAD. In conclusion, FAD can inhibit pathological cardiac hypertrophy and fibrosis through activating SCAD, which may be a novel effective treatment for pathological cardiac hypertrophy and fibrosis, thus prevent them from developing into heart failure.

Detection of allele frequencies of common c. 511C>T and c.625G>A variants in the ACADS gene in the Turkish population.

Short-chain acyl-CoA dehydrogenase deficiency (SCADD) is a rare inborn error of mitochondrial fatty acid oxidation and protein misfolding disorder. Our aim was to detect the number of Turkish patients diagnosed with SCADD in the literature and to determine the allele frequencies of two common variants (c.511C > T and c.625G > A) in the Turkish population. Five Turkish patients with SCADD were reported in the literature from four unrelated families. We also investigated allele frequencies of common variants of c.511C > T and c.625G > A, which confer susceptibility to SCADD, which were found to be 1.7% and 20.2%, respectively. Both of these susceptibility variants were found to be high in the Turkish population as they are worldwide.