Dominant ELOVL1 mutation causes neurological disorder with ichthyotic keratoderma, spasticity, hypomyelination and dysmorphic features.

BACKGROUND: Ichthyosis and neurological involvement occur in relatively few known Mendelian disorders caused by mutations in genes relevant both for epidermis and neural function. OBJECTIVES: To identify the cause of a similar phenotype of ichthyotic keratoderma, spasticity, mild hypomyelination (on MRI) and dysmorphic features (IKSHD) observed in two unrelated paediatric probands without family history of disease. METHODS: Whole exome sequencing was performed in both patients. The functional effect of prioritised variant in ELOVL1 (very-long-chain fatty acids (VLCFAs) elongase) was analysed by VLCFA profiling by gas chromatography-mass spectrometry in stably transfected HEK2932 cells and in cultured patient's fibroblasts. RESULTS: Probands shared novel heterozygous ELOVL1 p.Ser165Phe mutation (de novo in one family, while in the other family, father could not be tested). In transfected cells p.Ser165Phe: (1) reduced levels of FAs C24:0-C28:0 and C26:1 with the most pronounced effect for C26:0 (P=7.8×10-6 vs HEK293 cells with wild type (wt) construct, no difference vs naïve HEK293) and (2) increased levels of C20:0 and C22:0 (P=6.3×10-7, P=1.2×10-5, for C20:0 and C22:0, respectively, comparison vs HEK293 cells with wt construct; P=2.2×10-7, P=1.9×10-4, respectively, comparison vs naïve HEK293). In skin fibroblasts, there was decrease of C26:1 (P=0.014), C28:0 (P=0.001) and increase of C20:0 (P=0.033) in the patient versus controls. There was a strong correlation (r=0.92, P=0.008) between the FAs profile of patient's fibroblasts and that of p.Ser165Phe transfected HEK293 cells. Serum levels of C20:0-C26:0 FAs were normal, but the C24:0/C22:0 ratio was decreased. CONCLUSION: The ELOVL1 p.Ser165Phe mutation is a likely cause of IKSHD.

In Human and Mouse Spino-Cerebellar Tissue, Ataxin-2 Expansion Affects Ceramide-Sphingomyelin Metabolism.

Ataxin-2 (human gene symbol ATXN2) acts during stress responses, modulating mRNA translation and nutrient metabolism. Ataxin-2 knockout mice exhibit progressive obesity, dyslipidemia, and insulin resistance. Conversely, the progressive ATXN2 gain of function due to the fact of polyglutamine (polyQ) expansions leads to a dominantly inherited neurodegenerative process named spinocerebellar ataxia type 2 (SCA2) with early adipose tissue loss and late muscle atrophy. We tried to understand lipid dysregulation in a SCA2 patient brain and in an authentic mouse model. Thin layer chromatography of a patient cerebellum was compared to the lipid metabolome of Atxn2-CAG100-Knockin (KIN) mouse spinocerebellar tissue. The human pathology caused deficits of sulfatide, galactosylceramide, cholesterol, C22/24-sphingomyelin, and gangliosides GM1a/GD1b despite quite normal levels of C18-sphingomyelin. Cerebellum and spinal cord from the KIN mouse showed a consistent decrease of various ceramides with a significant elevation of sphingosine in the more severely affected spinal cord. Deficiency of C24/26-sphingomyelins contrasted with excess C18/20-sphingomyelin. Spinocerebellar expression profiling revealed consistent reductions of CERS protein isoforms, Sptlc2 and Smpd3, but upregulation of Cers2 mRNA, as prominent anomalies in the ceramide-sphingosine metabolism. Reduction of Asah2 mRNA correlated to deficient S1P levels. In addition, downregulations for the elongase Elovl1, Elovl4, Elovl5 mRNAs and ELOVL4 protein explain the deficit of very long-chain sphingomyelin. Reduced ASMase protein levels correlated to the accumulation of long-chain sphingomyelin. Overall, a deficit of myelin lipids was prominent in SCA2 nervous tissue at prefinal stage and not compensated by transcriptional adaptation of several metabolic enzymes. Myelination is controlled by mTORC1 signals; thus, our human and murine observations are in agreement with the known role of ATXN2 yeast, nematode, and mouse orthologs as mTORC1 inhibitors and autophagy promoters.

Rapamycin Inhibits Expression of Elongation of Very-long-chain Fatty Acids 1 and Synthesis of Docosahexaenoic Acid in Bovine Mammary Epithelial Cells.

Mammalian target of rapamycin complex 1 (mTORC1) is a central regulator of cell growth and metabolism and is sufficient to induce specific metabolic processes, including de novo lipid biosynthesis. Elongation of very-long-chain fatty acids 1 (ELOVL1) is a ubiquitously expressed gene and the product of which was thought to be associated with elongation of carbon (C) chain in fatty acids. In the present study, we examined the effects of rapamycin, a specific inhibitor of mTORC1, on ELOVL1 expression and docosahexaenoic acid (DHA, C22:6 n-3) synthesis in bovine mammary epithelial cells (BMECs). We found that rapamycin decreased the relative abundance of ELOVL1 mRNA, ELOVL1 expression and the level of DHA in a time-dependent manner. These data indicate that ELOVL1 expression and DHA synthesis are regulated by mTORC1 in BMECs.

Inhibition of Mammalian Target of Rapamycin Complex 1 (mTORC1) Downregulates ELOVL1 Gene Expression and Fatty Acid Synthesis in Goat Fetal Fibroblasts.

Elongation of very-long-chain fatty acids 1 (ELOVL1) is a ubiquitously expressed gene that belongs to the ELOVL family and regulates the synthesis of very-long-chain fatty acids (VLCFAs) and sphingolipids, from yeast to mammals. Mammalian target of rapamycin complex 1 (mTORC1) is a central regulator of cell metabolism and is associated with fatty acids synthesis. In this study, we cloned the cDNA that encodes Cashmere goat (Capra hircus) ELOVL1 (GenBank Accession number KF549985) and investigated its expression in 10 tissues. ELOVL1 cDNA was 840 bp, encoding a deduced protein of 279 amino acids, and ELOVL1 mRNA was expressed in a wide range of tissues. Inhibition of mTORC1 by rapamycin decreased ELOVL1 expression and fatty acids synthesis in Cashmere goat fetal fibroblasts. These data show that ELOVL1 expression is regulated by mTORC1 and that mTORC1 has significant function in fatty acids synthesis in Cashmere goat.

ELOVL1 is upregulated and promotes tumor growth in hepatocellular carcinoma through regulating PI3K-AKT-mTOR signaling.

Background: The functions of the ELOVLs are mainly involved in the elongation of saturated and polyunsaturated fatty acids, thus influencing the metabolism of fatty acids. Abnormal lipid metabolism may result in NAFLD and NASH, which may lead to cirrhosis and liver cancer. These results suggest that ELOVLs-mediated metabolism might be involved in the development of HCC. The purpose of this study was to study the expression and function of ELOVL1 in human liver cancer. Method: Using TCGA, GEPIA and other databases, we analyzed the relationship between the expression of ELOVL1 and liver cancer. The expression of ELOVL1 was detected by immunohistochemical method and Western blot method in hepatic carcinoma and hepatic carcinoma cells. Then, the effects of ELOVL1 on proliferation, apoptosis and invasion in vitro and in vivo were investigated by means of different methods. Result: Our results indicate that ELOVL1 is more highly expressed in liver cancer than in normal tissues. Survival analysis showed that OS and DSS were shorter in patients with high ELOVL1 expression than in those with low expression. Multivariate Cox analysis further demonstrated that over-expression of ELOVL1 was an independent risk factor for overall survival in HCC. The results of ROC also confirmed the value of ELOVL1 in the diagnosis of liver cancer. The results of KEGG enrichment and GSEA indicate that ELOVL1 is associated with lipid metabolism and NAFLD, as well as PPAR, PI3K-AKT-mTOR. Compared with the control group, it was found that silencing ELOVL1 in Huh7 and HepG2 cells could inhibit the growth of cells, promote the apoptosis and decrease the metastasis and invasion. Changes in ELOVL1 induced cell proliferation and metastasis may be related to PI3K/AKT/mTOR. Low expression of ELOVL1 inhibited the growth of xenograft tumors in hepatocellular carcinoma xenograft model. Conclusion: Our data indicate that the activation of PI3K/AKT/mTOR pathway in HCC may contribute to the promotion of cancer. Thus, ELOVL1 may be a promising therapeutic target for HCC.

Sexual dimorphism in hepatic PPAR alpha and CYP4a12a expression is associated with reduced development of drug-induced non-alcoholic steatohepatitis in female IL-33-/- mice.

Males are at higher risk for developing metabolic dysfunction-associated steatohepatitis (MASH) than females; however, mechanisms mediating sexual dimorphism in MASH development are not completely understood. Nutrition-based mouse models suggest that dysregulated fatty acid biosynthesis promotes MASH. Drugs recapitulate MASH without diet variabilities. This brief report investigates associations of sexual dimorphism with male susceptibility to MASH utilizing a drug-induced MASH model and focuses on very-long-chain fatty acid biosynthesis pathways. We assessed male and female mouse livers at 5 and 15 weeks following MASH induction by immunizations and age-matched un-immunized controls utilizing Western blot. Our results suggest that PPAR alpha and CYP4a12a protect females, while CYP4v2 does not protect males from MASH development. Our results have important implications for understanding sexual dimorphism in the pathogenesis of MASH.

Delayed simvastatin treatment improves neurological recovery after cryogenic traumatic brain injury through downregulation of ELOVL1 by inhibiting mTOR signaling.

Statins are well-tolerated and widely available lipid-lowering medications with neuroprotective effects against traumatic brain injury (TBI). However, whether delayed statin therapy starting in the subacute phase promotes recovery after TBI is unknown. Elongation of the very long-chain fatty acid protein 1 (ELOVL1) is involved in astrocyte-mediated neurotoxicity, but its role in TBI and the relationship between ELOVL1 and statins are unclear. We hypothesized that delayed simvastatin treatment promotes neurological functional recovery after TBI by regulating the ELOVL1-mediated production of very long-chain fatty acids (VLCFAs). ICR male mice received daily intragastric administration of 1, 2 or 5 mg/kg simvastatin on Days 1-14, 3-14, 5-14, or 7-14 after cryogenic TBI (cTBI). The results showed that simvastatin promoted motor functional recovery in a dose-dependent manner, with a wide therapeutic window of at least 7 days postinjury. Meanwhile, simvastatin inhibited astrocyte and microglial overactivation and glial scar formation, and increased total dendritic length, neuronal complexity and spine density on day 14 after cTBI. The up-regulation of ELOVL1 expression and saturated VLCFAs concentrations in the cortex surrounding the lesion caused by cTBI was inhibited by simvastatin, which was related to the inhibition of the mTOR signaling. Overexpression of ELOVL1 in astrocytes surrounding the lesion using HBAAV2/9-GFAP-m-ELOVL1-3xFlag-EGFP partially attenuated the benefits of simvastatin. These results showed that delayed simvastatin treatment promoted functional recovery and brain tissue repair after TBI through the downregulation of ELOVL1 expression by inhibiting mTOR signaling. Astrocytic ELOVL1 may be a potential target for rehabilitation after TBI.

Computational insight into structural basis of human ELOVL1 inhibition.

Very long-chain fatty acids (VLCFAs) play a direct role in the development of a neurological disorder, X-linked adrenoleukodystrophy (X-ALD). Since ELOVL1 catalyzes the rate-limiting step of the synthesis of VLCFAs, it has emerged as an attractive target for the treatment of X-ALD. Recently two potent inhibitors, compound 22 (C22) and compound 27 (C27) have been reported to specifically inhibit human ELOVL1 but their structural basis of inhibition has not been explored. In the present study, we have used a homology model of human ELOVL1 to deduce the binding site and binding modes of C22 and C27. We have employed computational approaches to characterize the binding of C22 and C27. Initially, binding of hexacosanoyl-CoA (C26:0-CoA) to ELOVL1 was modelled and further validated by molecular dynamics (MD) simulation. We observed that the fatty acid tail of C26: CoA protrudes from a unique opening located at the occluded end of ELOVL1. Structural comparison of ELOVL1 with the crystal structure of ELOVL7 revealed that the unique opening was not present in human ELOVL7. Combined blind and focused molecular docking approaches revealed that C22 and C27 exhibit favourable binding in the same unique opening. Further, MD simulations and free binding energy calculations confirmed that C22 and C27 maintain the favourable binding in the unique opening of ELOVL1. Overall, our findings suggest that selective human ELOVL1 inhibitors block the binding of long tails of VLCFAs near the occluded end of ELOVL1. Present study will be helpful in the discovery and design of novel, selective and potent inhibitors of human ELOVL1.

Involvement of ω-O-acylceramides and protein-bound ceramides in oral permeability barrier formation.

The permeability barrier present in the oral cavity is critical for protection from infection. Although lipids have properties suitable for permeability barrier formation, little is known about their role in oral barrier formation. Here, we show the presence of ω-O-acylceramides (acylceramides) and protein-bound ceramides, which are essential for the formation of permeability barriers in the epidermis, in the oral mucosae (buccal and tongue mucosae), esophagus, and stomach in mice. Conditional knockout of the fatty acid elongase Elovl1, which is involved in the synthesis of ≥C24 ceramides including acylceramides and protein-bound ceramides, in the oral mucosae and esophagus causes increased pigment penetration into the mucosal epithelium of the tongue and enhanced aversive responses to capsaicin-containing water. We find acylceramides in the buccal and gingival mucosae and protein-bound ceramides in the gingival mucosa in humans. These results indicate that acylceramides and protein-bound ceramides are important for oral permeability barrier formation.

ELOVLs Predict Distinct Prognosis Value and Immunotherapy Efficacy In Patients With Hepatocellular Carcinoma.

Background: Hepatocellular carcinoma (HCC) is a primary malignancy of the liver with high prevalence worldwide and poor prognosis. It has been verified that elongation of very-long-chain fatty acids gene family (ELOVLs), a group of genes that responsible for elongation of saturated and polyunsaturated fatty acids, participate in the pathogenesis and development of multiplex disease including cancers. However, the functions and prognosis of ELOVLs in HCC are still indistinguishable. Methods: First, we searched the mRNA expression and survival data of ELOVLs in patients with HCC via the data of The Cancer Genome Atlas (TCGA). The prognosis value of ELOVLs on HCC was assessed by Kaplan-Meier plotter and Cox regression analysis. reverse transcription quantitative- polymerase chain reaction (RT-qPCR), Western blot (WB), and immunohistochemistry were applied to assess the specific mRNA and protein expression of ELOVLs in HCC clinical specimens of our cohort. Then, the functional enrichment of ELOVL1 especially the pathways relating to the immune was conducted utilizing the Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and gene set enrichment analysis (GSEA) analysis. Additionally, TIMER, CIBERSOR, and tumor immune dysfunction and exclusion (TIDE) were employed to evaluate the relationship between ELOVL1 and immune responses. Last, the correlation of ELOVL1 with genome heterogeneity [microsatellite instability (MSI), tumor mutational burden (TMB), mutant-allele tumor heterogeneity (MATH), homologous recombination deficiency (HRD), purity, ploidy, loss of heterozygosity (LOH), and neoantigens] and mutational landscape were also evaluated basing on the date in TCGA. Results: Significant expression alteration was observed in ELOVLs family at the pan-cancer level. In liver cancer, ELOVL1 and ELOVL3 were strongly associated with poor prognosis of HCC by survival analysis and differential expression analysis. Immunohistochemistry microarray, WB, and RT-qPCR confirmed that ELOVL1 but not ELOVL3 played an important role in HCC. Mechanistically, functional network analysis revealed that ELOVL1 might be involved in the immune response. ELOVL1 could affect immune cell infiltration and immune checkpoint markers such as PD-1 and CTLA4 in HCC. Meanwhile, high expression of ELOVL1 would be insensitive to immunotherapy. Correlation analysis of immunotherapy markers showed that ELOVL1 has been associated with MSI, TMB, and oncogene mutations such as TP53. Conclusion: ELOVLs play distinct prognostic value in HCC. ELOVL1 could predict the poor prognosis and might be a potential indicator of immunotherapy efficacy in HCC patients.

Hypomyelinating spastic dyskinesia and ichthyosis caused by a homozygous splice site mutation leading to exon skipping in ELOVL1.

INTRODUCTION: Next generation sequencing technologies allow detection of very rare pathogenic gene variants and uncover cerebral palsy. Herein, we describe two siblings with cerebral palsy due to ELOVL1 splice site mutation in autosomal recessive manner. ELOVL1 catalyzes fatty acid elongation to produce very long-chain fatty acids (VLCFAs; ≥C21), most of which are components of sphingolipids such as ceramides and sphingomyelins. Ichthyotic keratoderma, spasticity, hypomyelination, and dysmorphic facies (MIM: 618527) stem from ELOVL1 gene deficiency in human. METHODS: We have studied a consanguineous family with whole exome sequencing (WES) and performed in depth analysis of cryptic splicing on the molecular level using RNA. Comprehensive analysis of ceramides in the skin stratum corneum of patients using liquid chromatography-tandem mass spectrometry (LC-MS/MS). ELOVL1 protein structure was computationally modelled. RESULTS: The novel c.376-2A > G (ENST00000372458.8) homozygous variant in the affected siblings causes exon skipping. Comprehensive analysis of ceramides in the skin stratum corneum of patients using LC-MS/MS demonstrated significant shortening of fatty acid moieties and severe reduction in the levels of acylceramides. DISCUSSION: It has recently been shown that disease associated variants of ELOVL1 segregate in an autosomal dominant manner. However, our study for the first time demonstrates an alternative autosomal recessive inheritance model for ELOVL1. In conclusion, we suggest that in ultra-rare diseases, being able to identify the inheritance patterns of the disease-associated gene or genes can be an important guide to identifying the molecular mechanism of genetic cerebral palsy.

Defining the fetal origin of MLL-AF4 infant leukemia highlights specific fatty acid requirements.

Infant MLL-AF4-driven acute lymphoblastic leukemia (ALL) is a devastating disease with dismal prognosis. A lack of understanding of the unique biology of this disease, particularly its prenatal origin, has hindered improvement of survival. We perform multiple RNA sequencing experiments on fetal, neonatal, and adult hematopoietic stem and progenitor cells from human and mouse. This allows definition of a conserved fetal transcriptional signature characterized by a prominent proliferative and oncogenic nature that persists in infant ALL blasts. From this signature, we identify a number of genes in functional validation studies that are critical for survival of MLL-AF4+ ALL cells. Of particular interest are PLK1 because of the readily available inhibitor and ELOVL1, which highlights altered fatty acid metabolism as a feature of infant ALL. We identify which aspects of the disease are residues of its fetal origin and potential disease vulnerabilities.

Dataset of the human homologues and orthologues of lipid-metabolic genes identified as DAF-16 targets their roles in lipid and energy metabolism.

The data presented in this article are related to the review article entitled 'Unravelling the role of fatty acid metabolism in cancer through the FOXO3-FOXM1 axis' (Saavedra-Garcia et al., 2017) [24]. Here, we have matched the DAF-16/FOXO3 downstream genes with their respective human orthologues and reviewed the roles of these targeted genes in FA metabolism. The list of genes listed in this article are precisely selected from literature reviews based on their functions in mammalian FA metabolism. The nematode Caenorhabditis elegans gene orthologues of the genes are obtained from WormBase, the online biological database of C. elegans. This dataset has not been uploaded to a public repository yet.