Proteomic analysis discovers potential biomarkers of early traumatic axonal injury in the brainstem.

OBJECTIVE: Application of Tandem Mass Tags (TMT)-based LC-MS/MS analysis to screen for differentially expressed proteins (DEPs) in traumatic axonal injury (TAI) of the brainstem and to predict potential biomarkers and key molecular mechanisms of brainstem TAI. METHODS: A modified impact acceleration injury model was used to establish a brainstem TAI model in Sprague-Dawley rats, and the model was evaluated in terms of both functional changes (vital sign measurements) andstructural changes (HE staining, silver-plating staining and ß-APP immunohistochemical staining). TMT combined with LC-MS/MS was used to analyse the DEPs in brainstem tissues from TAI and Sham groups. The biological functions of DEPs and potential molecular mechanisms in the hyperacute phase of TAI were analysed by bioinformatics techniques, and candidate biomarkers were validated using western blotting and immunohistochemistry on brainstem tissues from animal models and humans. RESULTS: Based on the successful establishment of the brainstem TAI model in rats, TMT-based proteomics identified 65 DEPs, and bioinformatics analysis indicated that the hyperacute phase of TAI involves multiple stages of biological processes including inflammation, oxidative stress, energy metabolism, neuronal excitotoxicity and apoptosis. Three DEPs, CBR1, EPHX2 and CYP2U1, were selected as candidate biomarkers and all three proteins were found to be significantly expressed in brainstem tissue 30 min-7 days after TAI in both animal models and humans. CONCLUSION: Using TMT combined with LC-MS/MS analysis for proteomic study of early TAI in rat brainstem, we report for the first time that CBR1, EPHX2 and CYP2U1 can be used as biomarkers of early TAI in brainstem by means of western blotting and immunohistochemical staining, compensating for the limitations of silver-plating staining and ß-APP immunohistochemical staining, especially in the case of very short survival time after TAI (shorter than 30 min). A number of other proteins that also have a potential marker role are also presented, providing new insights into the molecular mechanisms, therapeutic targets and forensic identification of early TAI in brainstem.

CYP2U1: An emerging treatable neurometabolic disease with cerebral folate deficiency in 2 Chinese brothers.

With the rapid advancement of medical technologies in genomic and molecular medicine, the number of treatable neurometabolic diseases is quickly expanding. Spastic paraplegia 56 (SPG56), one of the severe autosomal recessive forms of neurodegenerative disorders caused by pathogenic variants in the CYP2U1 gene, has no reported specific targeted treatment yet. Here we report 2 Chinese brothers with CYP2U1 bi-allelic pathogenic variants with cerebral folate deficiency who were treated for over a decade with folinic acid supplement. Patients have remained stable under therapy.

Co-occurrence of CLCN2-related leukoencephalopathy and SPG56.

Family Report: Two rare autosomal recessive neurological disorders, leukoencephalopathy with ataxia and spastic paraplegia 56 (SPG56), were found in members of the same family. Two siblings presented with spastic paraplegia, cognitive impairment, bladder and bowel dysfunction and gait ataxia; their consanguineous parents were unaffected. Ophthalmological examination revealed chorioretinopathy. Brain MRI showed T2 hyperintensities and T1 hypointensities in the internal capsules, cerebral peduncles, pyramidal tracts and middle cerebellar peduncles. Both affected siblings were homozygous for CYP2U1 c.947A > T p.(Asp316Val), a known cause for SPG56. However, they were also homozygous for the novel variant CLCN2 c.607G > T, p.(Gly203Cys), classified as a variant of unknown significance. Testing of additional family members revealed homozygosity for both variants in an additional brother, whom we initially considered unaffected. Both male CLCN2 carriers were infertile, and review of the literature revealed one reported case with azoospermia, however the brother had no overt signs of SPG56. His testicular biopsy revealed incomplete maturation arrest in spermatogenesis; clinically we found mild memory impairment and hand tremor and MRI showed similar changes as his siblings. We consider CLCN2 c.607G > T pathogenic because of the neuroradiological and clinical findings, including azoospermia. Conclusion: Considerable workup may be required to determine the pathogenicity of novel variants, and to unambiguously associate phenotype with genotype. In very rare disorders, highly specific clinical or biomarker combinations provide sufficient evidence for a variant's pathogenicity. Phenotypic variation of monogenic disorders described in the literature may be attributed to a second co-occurring monogenic disorder, especially in consanguineous families. SPG56 may have reduced penetrance.

Genetic diversity and population structure of muscovy duck (Cairina moschata) from Nigeria.

The domestic Muscovy duck (Cairina moschata) provide unique genetic resources patterned by both tropical environmental conditions and human activities, the evaluation of their genetic diversity and population structure will shade light on the mechanism of their remarkable adaptive capacities. We therefore analyzed the variation in mtDNA cytochrome b and nuclear DNA CYP2U1 sequences of 378 Nigerian Muscovy ducks (comprising of 287 de novo and 91 downloaded) plus 80 published sequences of Muscovy ducks from India. The results showed high haplotype diversity (0.800 ± 0.023) among Nigerian Muscovy duck populations with 91 distinct haplotypes for the nuclear DNA CYP2U1 gene but low (0.266 ± 0.033) for cytochrome b with 31 haplotypes. The median-joining networks of both markers grouped Nigerian Muscovy ducks into two; the first group consisting of only Nigerian Muscovy duck populations, and the second group Nigerian with Indian populations. Neutrality test results indicated that Nigerian populations experienced recent population expansion and/or genetic hitchhiking. A geographic signal was absent in line with previously studied poultry species in Nigeria. The most prominent haplotype dominated across all regions in Nigeria, which may be due to extensive genetic intermixing except for the Indian population (F ST = 0.02550, P = 0.01075). This indicated low genetic differentiation between and within Nigerian Muscovy duck as revealed by the suitability of the nuclear DNA CYP2U1 gene.

Macular Dystrophy with Bilateral Macular Telangiectasia Related to the CYP2U1 Pathogenic Variant Assessed with Multimodal Imaging Including OCT-Angiography.

PURPOSE: We report the case of a neurologically asymptomatic young boy presenting with an unusual phenotype of CYP2U1 related macular dystrophy associating bilateral macular telangiectasia (MacTel) and fibrotic choroidal neovascularization (CNV), assessed with complete multimodal imaging including optical coherence tomography angiography (OCT-A). CASE PRESENTATION: A twelve-year-old boy from a non-consanguineous family complained of bilateral progressive visual loss and photophobia. The best-corrected visual acuity was 2/10 on the right eye and 3/10 on the left eye. Fundus examination showed central pigmented fibrotic macular scar and yellowish punctuate deposits in both eyes. En face OCT-A detected typical macular telangiectasia (MacTel) in both eyes with dilated telangiectatic capillaries in the deep capillary plexus associated with vascular anomalies in the superficial and deep capillary plexus. Typical hypo-reflective cavities were observed within the inner foveal layers on structural OCT. En face OCT-A also confirmed the presence of bilateral inactive CNV within the fibrotic scars, showing high-flow vascular network at the level of the subretinal hyperreflective lesions. Whole exome sequencing identified a known homozygous pathogenic variant in CYP2U1 gene (c.1168C > T, p.Arg390*), which is a disease-causing mutation in autosomal recessive spastic paraplegia type 56 (SPG56). The neurological examination was normal, and electromyography and brain magnetic resonance imaging were unremarkable as well. CONCLUSION: Macular dystrophy can be the first manifestation in SPG56. A particular phenotype with MacTel was observed, and neovascular complications are possible. CYP2U1 should be included in the panels of genes tested for macular dystrophies, especially in the presence of MacTel and/or neurological manifestations.

Spastic Paraplegia-56 due to a Novel CYP2U1 Truncating Mutation in an Indian Boy: A New Report and Literature Review.

Spastic paraplegia-56 is a rare autosomal recessive disorder, caused by homozygous or compound heterozygous mutations in the CYP2U1 gene, located on chromosome 4. Till date, only 28 patients with this disorder have been reported in the literature. We report a new case of CYP2U1-related spastic paraplegia-56. We also reviewed previously published patients with this condition from various databases. Next-generation sequencing in the index child detected a novel homozygous two base pair deletion in exon 2 of the CYP2U1 gene that results in a frameshift and premature truncation of the protein 19 amino-acid downstream to codon 361. Together with the presented case, 29 were available for analysis. The mean age at the diagnosis was 17.84 ± 6.86 years. Intellectual disability/cognitive dysfunction and delayed walking or gait disturbance were the most common presenting features. Around half of the patients had neuroregression in between 1 and 2 years. It is clinically imperative to suspect this disease in children with early-onset spastic paraparesis, especially in cases accompanied by baseline development delay or cognitive impairment and consanguinity.

Pseudoxanthoma elasticum overlaps hereditary spastic paraplegia type 56.

PURPOSE: Pseudoxanthoma elasticum (PXE) is a recessive disorder involving skin, eyes and arteries, mainly caused by ABCC6 pathogenic variants. However, almost one fifth of patients remain genetically unsolved despite extensive genetic screening of ABCC6, as illustrated in a large French PXE series of 220 cases. We searched for new PXE gene(s) to solve the ABCC6-negative patients. METHODS: First, family-based exome sequencing was performed, in one ABCC6-negative PXE patient with additional neurological features, and her relatives. CYP2U1, involved in hereditary spastic paraplegia type 56 (SPG56), was selected based on this complex phenotype, and the presence of two candidate variants. Second, CYP2U1 sequencing was performed in a retrospective series of 46 additional ABCC6-negative PXE probands. Third, six additional SPG56 patients were evaluated for PXE skin and eye phenotype. Additionally, plasma pyrophosphate dosage and functional analyses were performed in some of these patients. RESULTS: 6.4% of ABCC6-negative PXE patients (n = 3) harboured biallelic pathogenic variants in CYP2U1. PXE skin lesions with histological confirmation, eye lesions including maculopathy or angioid streaks, and various neurological symptoms were present. CYP2U1 missense variants were confirmed to impair protein function. Plasma pyrophosphate levels were normal. Two SPG56 patients (33%) presented some phenotypic overlap with PXE. CONCLUSION: CYP2U1 pathogenic variants are found in unsolved PXE patients with neurological findings, including spastic paraplegia, expanding the SPG56 phenotype and highlighting its overlap with PXE. The pathophysiology of ABCC6 and CYP2U1 should be explored to explain their respective role and potential interaction in ectopic mineralization.

Bta-miR-130a/b regulates preadipocyte differentiation by targeting PPARG and CYP2U1 in beef cattle.

Deposition of intramuscular fat (IMF) is one of the most important traits for the evaluation of beef carcass quality grade. MicroRNA (miRNA) is an endogenous non-coding RNA that can play a role in the post-transcriptional regulation of mammalian preadipocyte differentiation. Previously, we identified that bta-miR-130a regulates milk fat biosynthesis by targeting PPARG mRNA. However, the role of miR-130 in the regulation of bovine adipocyte differentiation remains unknown. In this study, we found that overexpression of bta-miR-130a/b led to significantly decreased cellular triacylglycerol (TAG) levels during adipogenesis process as well as reduced lipid droplet formation. In contrast, the inhibition of bta-miR-130a/b resulted in larger lipid droplets and TAG accumulation. In addition, overexpression of bta-miR-130a/b inhibited the expression of adipocyte differentiation-related genes, including PPARG, C/EBPα, C/EBPß, FABP4, LPIN1, and LPL. Western blot analysis verified qPCR results on the expression of PPARG and CYP2U1. A luciferase reporter assay further verified bta-miR-130a/b significantly affects PPARG and CYP2U1 expression by directly binding to their 3'-untranslated regions (UTR). We conducted in vitro rescue assay to confirm that bta-miR-130a/b affect bovine adipocyte differentiation by targeting PPARG and CYP2U1. This study shows that bta-miR-130a and bta-miR-130b play similar roles in the regulation of adipocyte differentiation in beef muscles by targeting the 3'UTR of PPARG and CYP2U1. Our result provides a reference for illustrating how noncoding RNAs affects beef quality traits in cattle.

Genetic diversity and relationship of Indian Muscovy duck populations.

Assessment of genetic diversity within and between populations is a prerequisite for sustainable utilization of domestic species. The domestic Muscovy duck (Cairina moschata) is an economically important species around the world for its unique meat taste and low-caloric content. It is one of the important domestic species in India as it ensures food security to the rural sectors. In this study, we have analyzed the genetic diversity and relationship of four Muscovy duck populations collected from different states (Assam, Mizoram, Odisha and Kerala) of India using mtDNA cytochrome b and nuclear DNA CYP2U1 genes. The results showed low genetic diversity among populations for both the genes. Kerala population showed significant genetic differences from the other three populations. The median joining network of cytochrome b gene suggested that the domestic Muscovy ducks present in India are the product of a single domestication event and probably introduced to India several years ago, as reported elsewhere. This study has also showed the suitability of nuclear DNA CYP2U1 gene in genetic diversity analysis.

CYP2U1 activity is altered by missense mutations in hereditary spastic paraplegia 56.

Hereditary spastic paraplegia (HSP) is an inherited disorder of the central nervous system mainly characterized by gradual spasticity and weakness of the lower limbs. SPG56 is a rare autosomal recessive early onset complicated form of HSP caused by mutations in CYP2U1. The CYP2U1 enzyme was shown to catalyze the hydroxylation of arachidonic acid. Here, we report two further SPG56 families carrying three novel CYP2U1 missense variants and the development of an in vitro biochemical assay to determine the pathogenicity of missense variants of uncertain clinical significance. We compared spectroscopic, enzymatic, and structural (from a 3D model) characteristics of the over expressed wild-type or mutated CYP2U1 in HEK293T cells. Our findings demonstrated that most of the tested missense variants in CYP2U1 were functionally inactive because of a loss of proper heme binding or destabilization of the protein structure. We also showed that functional data do not necessarily correlate with in silico predictions of variants pathogenicity, using different bioinformatic phenotype prediction tools. Our results therefore highlight the importance to use biological tools, such as the enzymatic test set up in this study, to evaluate the effects of newly identified variants in clinical settings.

CYP2U1 mutations in two Iranian patients with activity induced dystonia, motor regression and spastic paraplegia.

Hereditary spastic paraplegia (HSP) is a heterogeneous condition characterized by progressive spasticity and weakness in the lower limbs. It is divided into two major groups, complicated and uncomplicated, based on the presence of additional features such as intellectual disability, ataxia, seizures, peripheral neuropathy and visual problems. SPG56 is an autosomal recessive form of HSP with complicated and uncomplicated manifestations, complicated being more common. CYP2U1 gene mutations have been identified as responsible for SPG56. Intellectual disability, dystonia, subclinical sensory motor neuropathy, pigmentary degenerative maculopathy, thin corpus callosum and periventricular white-matter hyperintensities were additional features noted in previous cases of SPG56. Here we identified two novel mutations in CYP2U1 in two unrelated patients by whole exome sequencing. Both patients had complicated HSP with activity-induced dystonia, suggesting dystonia as an additional finding in SPG56. Two out of 14 previously reported patients had dystonia, and the addition of our patients suggests dystonia in a quarter of SPG56 patients. Developmental regression has not been reported in SPG56 patients so far but both of our patients developed motor regression in infancy.

Hereditary spastic paraplegia: Novel mutations and expansion of the phenotype variability in SPG56.

We describe a novel sporadic case of SPG56, a rare complicated form of HSP, that expands the clinical and molecular spectrum of the disease, being associated to novel mutations in CYP2U1 and showing as novel feature dorsal hydromyelia at spinal cord MRI. The patient presented an early-onset, slowly progressive paraparesis associated with mild mental retardation. Neurological assessments included the Spastic Paraplegia Rating Scale (SPRS), Mental Deterioration Battery (MDB), and Wechsler Adult Intelligence Scale (WAIS), neurophysiological and neuroimaging studies. Targeted next-generation sequencing panels for the whole set of genes associated with HSP were performed in the probands and her relatives. Neuroimaging studies showed dorsal hydromyelia but no brain MRI abnormalities. Targeted next-generation identified two novel mutations: the c.5C > A/p.S2* on the maternal allele in compound heterozygosity with the paternally-inherited c.1288+5G > C in CYP2U1. Both mutations predict early protein truncation and a loss of function. So far, only few SPG56 cases have been reported. This case, expands and further characterize the clinical and molecular spectrum of SPG56. In this regard, in consideration of the putative gene function in neurodevelopment, we suggest a causal association between CYP2U1 mutations and hydromyelia in our patient.

Pigmentary degenerative maculopathy as prominent phenotype in an Italian SPG56/CYP2U1 family.

SPG56 is an autosomal recessive form of hereditary spastic paraplegia (HSP) associated with mutations in CYP2U1. There is no clear documentation of visual impairment in the few reported cases of SPG56, although this form is complex on clinical ground and visual deficit are extremely frequent in complicated HSP. We report three patients in a consanguineous family harboring the novel homozygous c.1168C>T (p.R390*) in SPG56/CYP2U1, and showing a pigmentary degenerative maculopathy associated with progressive spastic paraplegia. Furthermore, we characterized precisely the ophthalmologic phenotype through indirect ophthalmoscopy, retinal optical coherence tomography and visual evoked potentials. This is the first formal report of pigmentary degenerative maculopathy associated with a CYP2U1 homozygous mutation.

Expression of CYP2E1 and CYP2U1 proteins in amygdala and prefrontal cortex: influence of alcoholism and smoking.

BACKGROUND: The tissue-specific expression of cytochrome P450 enzymes (CYP, P450) in the human brain may influence the therapeutic response to, and side effects of, neuroactive drugs including alcohol. However, the distribution of many P450s, especially poorly characterized CYP2 forms, within specific regions of the brain remains obscure, partly due to the paucity of available tissue and difficulty in discriminating between related P450s with available antibodies. METHODS: In this study, we analyzed the expression of CYP2A6, CYP2B6, CYP2D6, CYP2E1, CYP2J2, CYP2S1, CYP2U1, and CYP2W1 proteins in human prefrontal cortex (PFC) and amygdala (AMG) by immunoblotting with antibodies for which the P450 form specificity had been enhanced by affinity purification. These brain regions were selected as they mediate the addictive effects of cigarette smoking and alcohol consumption, substances known to modulate P450 expression in other tissues. PFC and AMG samples from alcoholic smokers, alcoholic nonsmokers, nonalcoholic smokers, and nonalcoholic nonsmokers were studied to assess the effect of alcohol use and smoking on the expression of these proteins. RESULTS: Of the P450s studied, CYP2E1 and CYP2U1 were expressed in all samples analyzed (n = 26 and 22 for CYP2E1 and CYP2U1, respectively), and elevated in alcoholics. CYP2U1 expression was also slightly increased in smokers. Expression of both P450s was increased in AMG compared to PFC of the same individuals. CONCLUSIONS: This is the first report of CYP2E1 and CYP2U1 protein expression in human AMG. Our results suggest that CYP2U1 expression may be modulated by alcohol and tobacco, with potential consequent effects on the metabolism of drugs and endogenous chemicals by this enzyme.