Emopamil Binding Protein Gene Research Articles

Evolution, Expression Profile, Regulatory Mechanism, and Functional Verification of EBP-Like Gene in Cholesterol Biosynthetic Process in Chickens (Gallus Gallus).

The emopamil binding protein (EBP) is an important enzyme participating in the final steps of cholesterol biosynthesis in mammals. A predictive gene EBP-like, which encodes the protein with a high identity to human EBP, was found in chicken genome. No regulatory mechanisms and biological functions of EBP-like have been characterized in chickens. In the present study, the coding sequence of EBP-like was cloned, the phylogenetic trees of EBP/EBP-like were constructed and the genomic synteny of EBP-like was analyzed. The regulatory mechanism of EBP-like were explored with in vivo and in vitro experiments. The biological functions of EBP-like in liver cholesterol biosynthetic were examined by using gain- or loss-of-function strategies. The results showed that chicken EBP-like gene was originated from a common ancestral with Japanese quail EBP gene, and was relatively conservative with EBP gene among different species. The EBP-like gene was highly expressed in liver, its expression level was significantly increased in peak-laying stage, and was upregulated by estrogen. Inhibition of the EBP-like mRNA expression could restrain the expressions of EBP-like downstream genes (SC5D, DHCR24, and DHCR7) in the cholesterol synthetic pathway, therefore downregulate the liver intracellular T-CHO level. In conclusion, as substitute of EBP gene in chickens, EBP-like plays a vital role in the process of chicken liver cholesterol synthesis. This research provides a basis for revealing the molecular regulatory mechanism of cholesterol synthesis in birds, contributes insights into the improvement of the growth and development, laying performance and egg quality in poultry.

Conradi–Hünermann–Happle syndrome: report of a novel heterozygous mutation on the emopamil-binding protein gene, c.333delC

Conradi-Hünermann-Happle Syndrome, also called X-linked rhizomelic chondrodysplasia punctata, is a rare genodermatosis that presents with cutaneous, skeletal, and ophthalmological abnormalities. Herein, we report a full-term newborn that presented at birth with scattered blaschkolinear bands of adherent scales and scalp erosions in a spiral distribution. Genetic analysis of emopamil-binding protein gene revealed a previously undescribed heterozygous mutation of c.333delC.

Conradi–Hunermann syndrome: A rare case of chondrodysplasia punctata

Conradi–Hunermann syndrome is a common form of chondrodysplasia punctata, inherited as X-linked dominant disorder of cholesterol metabolism due to mutation of emopamil-binding protein gene resulting in a spectrum of skeletal, cutaneous, and ocular abnormalities. One-day-old premature, cesarean-delivered female neonate admitted with xerotic, featherlike yellow-to-white hyperkeratotic scale all over the body with craniofacial defect, coarse hair, patches of cicatricial alopecia, and absent eyebrows. Baby had rhizomelic shortening of proximal limb, clinodactyly, club foot, talipes equinovarus, and bilateral congenital cataract. Radiological skeletal survey revealed punctate stippled calcification involving left femoral head epiphysis, bilateral tarsal bones, vertebral bodies of multiple thoracolumbar vertebrae, and sternum. Serum level of 8-dehydrocholesterol was elevated. Diagnosis of rare disease can be made on clinical suspicion and radiological survey in resource-limited setting.

Single-cell analysis reveals the relevance of foot-and-mouth disease virus persistence to emopamil-binding protein gene expression in host cells.

Foot-and-mouth disease virus (FMDV) infects host cells in either an acute or persistent manner. In this study, we examined the relevance of the establishment of FMDV persistence to the expression of the emopamil-binding protein (EBP) gene in 231 individual persistently infected baby hamster kidney (BHK-21) cells after passages 28, 38, and 68 (PI28, PI38, and PI68). At PI28, the stage at which persistent infection of FDMV becomes unstable, the percentage of cells carrying FMDV was 66.7%, while 80.2% of cells were EBP positive. Additionally, in 55.6% of the EBP-positive cells at PI28, EBP expression was upregulated approximately 149.9% compared to uninfected BHK-21 cells. This was the highest expression level among all cell passages measured. Interestingly, in a parallel experiment, the average EBP expression level in the whole cell population at PI28 was only slightly higher (108.2%) than that in uninfected BHK-21 cells. At PI38, 98.7% of the cells were positive for FMDV 3D (an RNA-dependent RNA polymerase enzyme gene), and its maximum expression level observed at this passage. The expression level of EBP in 78.2% of the total cells, however, was reduced significantly. At PI68, 95.8% of the cells were 3D positive, and the expression of both the EBP and 3D genes were at the lowest levels of all the passages. Our studies using single cells yielded data that are otherwise inaccessible a using whole cell population. These results suggest that the establishment of persistent infection by FMDV is a dynamic process that results from the continuous adaptation and coevolution of viruses and cells to reach an equilibrium.

Conradi-Hünermann-Happle syndrome in males vs. MEND syndrome (male EBP disorder with neurological defects)

There is confusion in the literature concerning disorders caused by EBP (emopamil-binding protein) mutations in males. To study the clinical and genetic differences in males affected either with Conradi-Hünermann-Happle (CHH) syndrome (X-linked dominant chondrodysplasia punctata, CDPX2) or with a nonmosaic, X-linked recessive disorder for which we propose the acronymic term MEND syndrome (male EBP disorder with neurological defects). We report a 7-year-old boy with a history of transient scaly erythematous lesions on his limbs, trunk and scalp soon after birth. DNA was isolated from ethylenediamine tetraacetic acid-blood samples of the patient and the four coding exons of the EBP gene were amplified by polymerase chain reaction. We review all published cases of CHH syndrome in males in the literature and elaborate the clinical and genetic differences between CHH syndrome in males and MEND syndrome. We found at position 33 of the EBP gene the variant c.33C>A leading to the same nonsense mutation p.Y11X that had previously occurred de novo in a female with typical manifestations of CHH syndrome. When the known male cases with EBP mutations were reviewed, a striking nosological difference between the mosaic and nonmosaic phenotypes was evident. Clear-cut clinical criteria are elaborated to distinguish between CHH syndrome in males and MEND syndrome. Because the clinical outcome and prognosis are different it is important to distinguish between males with CHH syndrome that represents a mosaic phenotype, and those with MEND syndrome that is a nonmosaic trait.

Clinical, molecular and biochemical characterization of nine Spanish families with Conradi-Hünermann-Happle syndrome: new insights into X-linked dominant chondrodysplasia punctata with a comprehensive review of the literature

Conradi-Hünermann-Happle syndrome (CDPX2, OMIM 302960) is an inherited X-linked dominant variant of chondrodysplasia punctata which primarily affects the skin, bones and eyes. CDPX2 results from mutations in EBP (emopamil binding protein), and presents with increased levels of sterol precursors 8(9)-cholesterol and 8-dehydrocholesterol. To expand the understanding of CDPX2, clinically, biochemically and genetically. We present one of the largest series reported to date, including 13 female patients belonging to nine Spanish families. Patients were studied biochemically using gas chromatography-mass spectrometry, genetically using polymerase chain reaction and in their methylation status using the HUMARA assay. In our cases, there was a clear relationship between abnormal sterol profile and the EBP gene mutation. We describe three novel mutations in the EBP gene. EBP mutations were inherited in three out of nine families and were sporadic in the remaining cases. No clear genotype-phenotype correlation was found. Patients' biochemical profiles did not reveal a relationship between sterol profiles and severity of disease. A skewed X-chromosome inactivation may explain the clinical phenotype in CDPX2 in some familial cases.

Identification of VKORC1 interaction partners by split-ubiquitin system and coimmunoprecipitation

Since the discovery of vitamin K epoxide reductase complex subunit 1 (VKORC1), the key enzyme for the regeneration of vitamin KH₂, numerous studies have addressed the role of VKORC1 in the posttranslational modification of vitamin K-dependent proteins. VKORC1 is also the target protein of anticoagulant drugs of the coumarin type (e.g. warfarin). Genetic variants in VKORC1 have recently been shown to significantly affect the coumarin dose and international normalised ratio level. In the present study, we have used the split-ubiquitin yeast two-hybrid system to identify potential interaction partners of VKORC1. With this system we could identify 90 candidates. Out of these, we focused on VKORC1 itself, its paralog VKORC1L1, emopamil binding protein (EBP) and stress-associated endoplasmic reticulum protein 1 (SERP1). By coimmunprecipitation and colocalisation experiments, we were able to demonstrate evidence for the interaction of these proteins. Mutations in the EBP gene cause X-linked dominant chondrodysplasia punctata (CDPX2) which can be considered as a phenocopy of warfarin embryopathy. The interaction could be a link between these phenotypes. SERP1 represents an oxidative stress-associated endoplasmatic reticulum protein with chaperon-like functions. Antioxidant capacities have been described for vitamin K hydroquinone, the substrate of VKORC1. Both VKORC1 and SERP1, might have a synergistic function in eliminating reactive oxygen species generated during the VKOR redox process. Further studies are needed to investigate the role of these proteins in the vitamin K pathway.

Conradi-Hünermann-Happle Syndrome (X-linked Dominant Chondrodysplasia Punctata) Confirmed by Plasma Sterol and Mutation Analysis

Conradi-Hünermann-Happle syndrome, or X-linked dominant chondrodysplasia punctata, is a rare genetic disorder characterized by skeletal dysplasia, stippled epiphyses, cataracts, transient ichthyosis and atrophic residua in a mosaic pattern. Mutations in the gene encoding the emopamil-binding protein have been identified as an underlying cause. A 5-year-old girl presented for evaluation of ill-defined patches of cicatricial alopecia. In addition, subtle follicular atrophoderma, esotropia, craniofacial asymmetry and short stature were noted. Her history revealed widespread scaly erythema and eye surgery for congenital cataract in the first months of life. Diagnosis of Conradi-Hünermann-Happle syndrome was confirmed by plasma sterol analysis showing markedly elevated levels of 8(9)-cholestenol and 8-dehydrocholesterol and by detection of a missense mutation (c.307G>A; p.E103K) in the emopamil-binding protein gene. We suggest that plasma sterol analysis is a reliable method of establishing the diagnosis of Conradi-Hünermann-Happle syndrome, even in patients with less striking phenotypical changes beyond infancy.

Reduced penetrance in a family with X-linked dominant chondrodysplasia punctata

X-linked dominant chondrodysplasia punctata (Conradi–Hünermann disease, CDPX2) is characterised by short stature, stippled epiphyses, cataracts, ichthyosiform erythroderma and patchy alopecia of the scalp. The disorder is caused by mutations within the emopamil binding protein ( EBP) gene encoding a 3β-hydroxysteroid-Δ 8,Δ 7-isomerase. The intrafamilial variation of disease severity is a known feature of CDPX2 probably caused by skewed X-inactivation. We report on a female fetus with typical symptoms of CDPX2 such as short limbs, postaxial polydactyly, ichthyotic skin lesions and punctate calcifications. Molecular genetic analysis of the EBP gene revealed a nonsense mutation (c.328C > T, p.R110X), which was previously detected in one CDPX2 patient and in a second female patient, who was only affected on one body side and erroneously diagnosed as CHILD syndrome. Surprisingly, the mother of our fetus carries the same mutation without having any signs of CDPX2. X-inactivation studies did not reveal any evidence of skewing neither in the mother nor in the fetus.

Two novel frameshift mutations of the EBP gene in two unrelated Thai girls with Conradi-Hunermann-Happle syndrome.

Conradi-Hünermann-Happle syndrome, also known as X-linked dominant chondrodysplasia punctata (CDPX2), is characterized by skeletal abnormalities, cutaneous anomalies and cataracts. CDPX2 is caused by mutations in the emopamil-binding protein (EBP). We report two unrelated Thai female patients with clinically typical CDPX2, in which we discovered two novel and de novo frameshift mutations: 506-507delAG and 540-541delCC. This study demonstrates that EBP is the gene responsible for CDPX2 across different populations and extends the total number of confirmed mutations to 55.

Gas Chromatography–Mass Spectrometry and Molecular Genetic Studies in Families with the Conradi–Hünermann–Happle Syndrome

The Conradi-Hünermann-Happle syndrome is an X-linked dominant disease that is due to mutations in the gene for emopamil binding protein. Emopamil binding protein is a Delta8-Delta7 sterol isomerase and plays a pivotal role in the final steps of cholesterol biosynthesis. We wanted to know to what extent this X-linked dominant enzyme defect has functional consequences at the biochemical level and whether it is possible to predict the clinical phenotype from serum sterol measurements. Therefore we performed sterol biochemical studies in 11 Conradi-Hünermann-Happle syndrome families and compared the results obtained to the clinical and molecular genetic findings. To assess disease severity a score considering bone and skin involvement and further features was used. For evaluation of the functional consequences we studied serum samples using gas chromatography-mass spectrometry analysis. For mutation screening we analyzed the emopamil binding protein gene using polymerase chain reaction, heteroduplex analysis of all exons, direct sequencing, and restriction enzyme analysis. Mutations in the emopamil binding protein gene were found in all 11 families including seven novel mutations affecting exons 2, 4, and 5. Gas chromatography-mass spectrometry analysis revealed markedly elevated levels of 8-dehydrocholesterol and of cholest-8(9)-en-3beta-ol and helped to identify somatic mosaicism in a clinically unaffected man. The extent of the metabolic alterations in the serum, however, do not allow prediction of the clinical phenotype, nor the genotype. This lack of correlation may be due to differences in X-inactivation between different tissues of the same patient and/or loss of the mutant clone by outgrowth of proficient clones after some time.

Mouse Tdho abnormality results from double point mutations of the emopamil binding protein gene (Ebp).

Mouse Tdho (Tattered-Hokkaido) was described as being allelic with Td in our previous study. Both allelic genes, which are located at the same position on the centromere of the X Chromosome (Chr), generate similar phenotypes such as male embryonic lethality, and in heterozygous females, hyperkeratotic skin, skeletal abnormalities, and growth retardation. The emopamil binding protein gene (Ebp) emerged as a candidate for mouse Tdho mutation, since the Td gene was recently determined to result from a point mutation of Ebp. In this study, Ebp cDNA of Tdho was demonstrated to possess double point mutations that cause two amino acid changes from Leu to Pro at position 132 and from Ser to Cys at 133 in EBP protein. EBP participates in cholesterol biosynthesis, and cholest-8(9)-en-3beta-ol was found to be increased in the plasma of Tdho adult females but not in that of normal mice. From these results, a loss of function was expected for the EBP protein encoded by Tdho. Both the phenotypes and genes responsible for Tdho as well as Td are quite similar to those of human X-linked chondrodysplasia punctata (CDPX2).

The Conradi-Hünermann-Happle syndrome (CDPX2) and emopamil binding protein: novel mutations, and somatic and gonadal mosaicism.

The Conradi-Hünermann-Happle (CHH) syndrome (X-chromosomal dominant chondrodysplasia punctata type II; MIM 302960) is an X-linked dominant disorder that is characterized by ichthyosis, chondrodysplasia punctata, cataracts and short stature. The disease occurs almost exclusively in females and shows increased disease expression in successive generations (anticipation). Recently, causative mutations in the emopamil binding protein (EBP) have been identified. To better appreciate the genetics of this syndrome we analyzed the EBP gene in seven independent families using PCR, conformation-sensitive gel electrophoresis, direct sequencing and restriction enzyme analysis. We found five novel mutations: three nonsense mutations in exon 2 and exon 3 and two frameshift mutations, one deletion in exon 4 and an insertion in exon 5. In two families, known mutations affecting exon 2 were identified. Surprisingly, we failed to detect the mutation in a grandmother exhibiting minor disease symptoms such as sectorial cataract and attribute this to gonadal and somatic mosaicism. Gonadal mosaicism appeared also to be involved in the case of healthy parents having two affected girls, one of whom died due to the disease. We conclude that gonadal mosaicism has to be considered when dealing with seemingly sporadic cases.