SOX2-dependent expression of dihydroorotate dehydrogenase regulates oral squamous cell carcinoma cell proliferation / 国际口腔科学杂志·英文版

Oral squamous cell carcinoma (OSCC) become a heavy burden of public health, with approximately 300 000 newly diagnosed cases and 145 000 deaths worldwide per year. Nucleotide metabolism fuel DNA replication and RNA synthesis, which is indispensable for cell proliferation. But how tumor cells orchestrate nucleotide metabolic enzymes to support their rapid growth is largely unknown. Here we show that expression of pyrimidine metabolic enzyme dihydroorotate dehydrogenase (DHODH) is upregulated in OSCC tissues, compared to non-cancerous adjacent tissues. Enhanced expression of DHODH is correlated with a shortened patient survival time. Inhibition of DHODH by either shRNA or selective inhibitors impairs proliferation of OSCC cells and growth of tumor xenograft. Further, loss of functional DHODH imped de novo pyrimidine synthesis, and disrupt mitochondrial respiration probably through destabilizing the MICOS complex. Mechanistic study shows that transcriptional factor SOX2 plays an important role in the upregulation of DHODH in OSCC. Our findings add to the knowledge of how cancer cells co-opt nucleotide metabolism to support their rapid growth, and thereby highlight DHODH as a potential prognostic and therapeutic target for OSCC treatment.

Clinical features and genetic testing of a Chinese pedigree affected with Smith-Lemli-Opitz syndrome / 中华医学遗传学杂志

OBJECTIVE@#To analyze the clinical features and genetic variants of two patients from a pedigree affected with Smith-Lemli-Opitz syndrome and explore their genotype-phenotype correlation.@*METHODS@#Clinical data and family history of the pedigree were collected. Whole exome sequencing was carried out to identify the potential variants. Suspected variants were verified by Sanger sequencing of the family members.@*RESULTS@#The proband and her sister both presented with feeding difficulty, facial dysmorphism, seizures, and mental and speech retardation. The third child of this family presented with feeding difficulty, poor weight gain and severe malnutrition after birth. He had died of unknown cause at 6 months without genetic testing. The fourth child was a healthy boy. Genetic testing showed that both the proband and her sister have carried c.127G>T (p.Val43Phe) and c.820_825del (p.Asn274_Val275del) compound heterozygous variants of the DHCR7 gene (NM_001360.2), but the fourth child carried neither of the variants. The two variants were unreported in the literature and disease-related databases, and were not included in the 1000G and gnomAD databases. The c.820_825del variant may affect the sterol-sensitive region of the DHCR7 protein, which can lead to deletion of two amino acids at positions 247 and 275, causing truncation of the DHCR7 protein. It is speculated that this may affect the stability of protein's spatial conformation, thereby decrease the activity of the enzyme. The c.127G>T variant may affect the first transmembrane region of the protein, which is involved in the transmembrane transport of proteins. Multiple software predicted it to be harmful. Conservation analysis suggested that the three amino acids all locate in a highly conserved region of the protein. In consideration of the clinical phenotype, family history and result of genetic testing, we speculated that both patients had Smith-Lemli-Opitz syndrome due to variants of the DHCR7 gene.@*CONCLUSION@#This pedigree has enriched the phenotypic and genotypic data of Smith-Lemli-Opitz syndrome, which clarified the genetic etiology of the patients and provided a basis for genetic counseling of this pedigree.

Clinical and genetic analysis of a Chinese pedigree affected with Smith-Lemli-Opitz syndrome / 中华医学遗传学杂志

OBJECTIVE@#To explore the clinical phenotype and pathogenic variants in a Chinese pedigree affected with Smith-Lemli-Opitz syndrome.@*METHODS@#Peripheral blood samples were collected from five members, including two affected ones, from the pedigree for the extraction of genomic DNA. Whole exome sequencing was carried out, and candidate variants were verified by Sanger sequencing as well as reverse transcription sequencing at the RNA level.@*RESULTS@#The proband and another affected child from the pedigree showed mental retardation, dyskinesia, microcephaly, micrognathia, anteverted nares, and 2/3 toe syndactyly. The proband also had hypospadia, single upper incisor, and lower serum cholesterol level. Both children were found to harbor a paternally derived c.278C>T (p.T93M) variant and a maternally derived c.907G>A (p.G303R) variant of the DHCR7 gene. Both were known pathogenic mutations.@*CONCLUSION@#The compound heterozygous mutations of c.278C>T (p.T93M) and c.907G>A (p.G303R) of the DHCR7 gene probably underlay the disease in this pedigree. Above finding has enabled early diagnosis and treatment of Smith-Lemli-Opitz syndrome.

Structural characteristics and catalytic cycle of dihydroorotate dehydrogenase-a review / 生物工程学报

Dihydroorotate dehydrogenase is a flavin-dependent mitochondrial enzyme to catalyze the fourth step of the de novo synthesis of pyrimidine and to oxidize dihydroorotate to orotate. By selectively inhibiting dihydroorotate dehydrogenase, thereby inhibiting pyrimidine synthesis, the enzyme has been developed for the treatment of cancer, autoimmune diseases, bacterial or viral infections, parasitic diseases and so on. The development of inhibitory drugs requires a detailed understanding of the structural characteristics and catalytic cycle mechanism of dihydroorotate dehydrogenase. Therefore, this paper reviews these two aspects, and indicates perspectives of these inhibitors in clinical application.

The role of vitamin C in the gene expression of oxidative stress markers in fibroblasts from burn patients

Abstract Purpose: To assess the action of vitamin C on the expression of 84 oxidative stress related-genes in cultured skin fibroblasts from burn patients. Methods: Skin samples were obtained from ten burn patients. Human primary fibroblasts were isolated and cultured to be distributed into 2 groups: TF (n = 10, fibroblasts treated with vitamin C) and UF (n = 10, untreated fibroblasts). Gene expression analysis using quantitative polymerase chain reaction array was performed for comparisons between groups. Results: The comparison revealed 10 upregulated genes as follows: arachidonate 12-lipoxygenase (ALOX12), 24-dehydrocholesterol reductase (DHCR24), dual oxidase 1 (DUOX1), glutathione peroxidase 2 (GPX2), glutathione peroxidase 5 (GPX5), microsomal glutathione S-transferase 3 (MGST3), peroxiredoxin 4 (PRDX4), phosphatidylinositol-3,4,5-trisphosphate dependent Rac exchange factor 1 (P-REX1), prostaglandin-endoperoxide synthase 1 (PTGS1), and ring finger protein 7 (RNF7). Conclusion: Cultured fibroblasts obtained from burn patients and treated with vitamin C resulted in 10 differentially expressed genes, all overexpressed, with DUOX1, GPX5, GPX2 and PTGS1 being of most interest.

Influence of 7-dehydrocholesterol reductase gene silencing on the fusion of mouse palatal shelves / 华西口腔医学杂志

<p><b>OBJECTIVE</b>RNA interference was applied to knockdown the Dhcr7 gene in mouse embryonic palatal shelves to facilitate understanding of the function of Dhcr7 gene variants in the fusion of palatal shelves.</p><p><b>METHODS</b>The pAdTrack-CMV-siDhcr7 was constructed using the specific siRNA sequence of Dhcr7 from C57BL/6J mouse. The pAdTrack-CMV- siDhcr7 of positive clones was reconstructed in vitro, and the recombinant adenovirus pAdEasy-1-siDhcr7 of kanamycin resistance was screened. The adenovirus vector DNA was then prepared for transfecting the embryonic palatal shelves. Thirty pairs of embryonic palatal shelves at 13.5 d gestational age were harvested and then randomly divided into the following three groups: normal control group (n = 10), which included palatal shelves inculture medium without cholesterol; blank adenovirus control group (n = 10), which included palatal shelves in culture medium without cholesterol and blank adenovirus; and experimental group (n = 10), which included palatal shelves in culture medium without cholesterol and adenovirus encoding Dhcr7 siRNA. At 48 h after in vitro cultivation, the mRNA and protein of the palatal shelves were obtained for scanning electron microscopy (SEM), reverse transcription polymerase chain reaction (RT-PCR), and Western blot analyses.</p><p><b>RESULTS</b>SEM showed that the palatal shelves of the normal control and blank adenovirus control groups fused and formed continuous palates, whereas those of the experimental group was almost undeveloped but exhibited large gaps between the two palatal shelves. RT-PCR and Western blot analyses showed that the mRNA and protein of Dhcr7 in the experimental group decreased compared with those in the normal control group with a significant difference (P < 0.05).</p><p><b>CONCLUSION</b>Results indicate that Dhcr7 gene silencing affects the fusion of palatal shelves. Thus, Dhcr7 gene may serve a function in the normal development of palates.</p>

7-Dehydrocholesterol reductase regulated the palatal development by the sonic hedgehog-bone morphogenetic protein 2 signal pathway / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the effect of 7- dehydrocholesterol reductas (Dhcr-7) gene silencing on the palatal development by sonic hedgehog (Shh)-bone morphogenetic protein2(BMP-2) signal pathway in vitro.</p><p><b>METHODS</b>A total of 60 pairs of palatal shelves fromgestation day (GD) 13.5 mouse embryos were divided into three groups (A, B, C) of 20 randomly. In group A (control), palatal shelves were cultured with medium containing no cholesterol.In group B (Dhcr-7-siRNA), palatal shelves were cultured without cholesterol medium but containing Dhcr-7 siRNA adenovirus. After 48h, the culture medium of groups A and B were changed with medium without cholesterol. In group C (cholesterol), palatal shelves were cultured without cholesterol medium but containing Dhcr-7 siRNA adenovirus. After 48h, the culture medium of group C was changed with medium containing 600 mg/L cholesterol. After 72h again, tissues dyeing and scanning electron microscope (SEM) technique were used to observe morphological changes of palates. Both RT-PCR and Western blottingtechniques were used to measure mRNA and protein expressions for Dhcr-7, Shh, and BMP-2, respectively.</p><p><b>RESULTS</b>The tissues dyeing and SEM showedthat the palates fusedin groups A and Candthe palates did not fuse in group B eventually. The expression of both mRNA and proteins for Shh and BMP-2 in group B wasdecreased with the Dhcr-7 reduction. In group B, the mRNA and protein expression of Shh was separately 0.063±0.018 and 0.092±0.065;the mRNA and protein expression quantity of BMP- 2 was separately 0.054±0.018 and 0.049±0.021. In group A, the mRNA and protein expression of Shh was separately 0.667±0.093 and 0.639±0.078;the mRNA and protein expression of BMP-2 was separately 0.591 ± 0.043 and 0.569 ± 0.081. The difference of Shh and BMP- 2 mRNA and protein expression between A and B group were statistically significant separately (P < 0.05). The expression of both mRNA and protein for Dhcr-7 (0.074±0.034 and 0.075±0.028) did not changebasicallyin group C, compared with the Dhcr- 7expression of mRNA and protein (0.083±0.045; 0.067±0.065) in group B, the difference wasnot statistically significant(P > 0.05). In group C, the mRNA and protein expressionof Shh (0.649±0.085 and 0.608±0.092) and BMP-2 (0.578±0.062 and 0.548±0.065) were significantly increased. The difference of Shh and BMP-2 mRNA and protein expression between B and C group were statistically significant separately (P < 0.05).</p><p><b>CONCLUSIONS</b>Dhcr-7 could influence the expression of Shh and BMP-2. Dhcr-7 reductase regulated the palatal development by the Shh-BMP-2 signal pathway.</p>

Biliverdin reductase A in the prevention of cellular senescence against oxidative stress

Biliverdin reductase A (BLVRA), an enzyme that converts biliverdin to bilirubin, has recently emerged as a key regulator of the cellular redox cycle. However, the role of BLVRA in the aging process remains unclear. To study the role of BLVRA in the aging process, we compared the stress responses of young and senescent human diploid fibroblasts (HDFs) to the reactive oxygen species (ROS) inducer, hydrogen peroxide (H2O2). H2O2 markedly induced BLVRA activity in young HDFs, but not in senescent HDFs. Additionally, depletion of BLVRA reduced the H2O2-dependent induction of heme oxygenase-1 (HO-1) in young HDFs, but not in senescent cells, suggesting an aging-dependent differential modulation of responses to oxidative stress. The role of BLVRA in the regulation of cellular senescence was confirmed when lentiviral RNAitransfected stable primary HDFs with reduced BLVRA expression showed upregulation of the CDK inhibitor family members p16, p53, and p21, followed by cell cycle arrest in G0-G1 phase with high expression of senescence-associated beta-galactosidase. Taken together, these data support the notion that BLVRA contributes significantly to modulation of the aging process by adjusting the cellular oxidative status.

A Novel DHCR7 Mutation in a Smith-Lemli-Opitz Syndrome Infant Presenting with Neonatal Cholestasis

Smith-Lemli-Opitz syndrome (SLOS) is an autosomal recessive malformation syndrome caused by a defect in cholesterol biosynthesis. The incidence is very low in Asians and only one case has been reported in Korea thus far. Recently, we found an infant with neonatal cholestasis. He had microcephaly, ambiguous genitalia, cleft palate, syndactyly of toes, patent ductus arteriosus and hypertrophic pyloric stenosis. The serum cholesterol was decreased and serum 7-dehydrocholesterol was markedly elevated. Genetic analysis of the DHCR7 gene identified a novel missense mutation (Pro227Ser) as well as a known mutation (Gly303Arg) previously identified in a Japanese patient with SLOS. Although rare in Korea, SLOS should be considered in the differential diagnosis of neonatal cholestasis, especially in patients with multiple congenital anomalies and low serum cholesterol levels.

Role of bilirubin as antioxidant in neonatal jaundice and effect of ethanolic extract of sweet lime peel on experimentally induced jaundice in rat.

Bilirubin above a threshold level is toxic to human system and is excreted in urinary and through gastrointestinal tract. The role of bilirubin as antioxidant is debatable. This paper aims at elucidating the role of bilirubin as an antioxidant in neonatal jaundice patients. It is observed that bilirubin up to 6 mg/dl in blood acts as an antioxidant and above 12.5 mg/dl is strongly prooxidant. Phototherapy is the accepted therapeutic management of neonatal jaundice and has been shown to enhance the oxidative stress. Approaches have been taken to formulate a herbal medication which will reduce bilirubin level in the neonates without inducing additional damages. The ethanolic extract of sweet lime peel, administered orally at a dose of 72 microg is found to reduce the oxidative stress in erythrocytes of phenylhydrazine-induced jaundiced rats treated with phototherapy.

Molecular cloning and characterization of a novel isoflavone reductase-like gene (FcIRL) from high flavonoids-producing callus of Fagopyrum cymosum / 药学学报

Lignans are important defensive compounds in plants and have good biological activities protecting human health. In order to study the medicinal secondary metabolism of Fagopyrum cymosum (Trev.) Meisn, a traditional Chinese medicine with anti-tumor effect, a novel isoflavone reductase-like gene, FcIRL, was cloned using RACE strategy from a cDNA library of high flavonoids-producing callus. The full-length cDNA of the FcIRL was 1 217 bp (accession no. EU116032), which contained a 942 bp open reading frame (ORF) encoding a 313 amino acid protein. Two stop codons (TAG) and a putative polyadenylation signal ATAAA at 24 bp upstream from the polyadenylation site was found in 5' and 3' UTR, separately. And no intron was found in the genomic sequence yet. FcIRL contained a predicted N-terminal acetylation site (M1-K5) and a NADPH-binding motif (G10-G-T-G13-Y-I-G16) in the N-terminal region, a conserved NmrA (nitrogen metabolite repression regulator) domain (V6-N244), multi-phosphorylation sites and one conserved N-glycosylation site (N214). Sequence homology comparison, phylogenetic analysis and advanced structures prediction all suggested that FcIRL belonged to the class of pinoresinol-lariciresinol reductase (PLR), which is a key enzyme in synthetic pathway of 8-8'-linked lignans, with function in catalyzing reduction of pinoresinol and lariciresinol into secoisolariciresinol, and medicinal secondary metabolism and resistance in F. cymosum.

A case of Smith-Lemli-Opitz syndrome diagnosed by identification of mutations in the 7-dehydrocholesterol reductase (DHCR7) gene / 소아과

Smith-Lemli-Opitz syndrome (SLOS) is a rare, autosomal recessive disease caused by an inborn error in cholesterol synthesis. Patients with this disease suffer from multiple malformations due to reduced activity of 7-dehydrocholesterol reductase (DHCR7), which increases 7-dehydrocholesterol (7DHC) and 8-dehydrocholesterol (8DHC) concentrations and decreases cholesterol concentration in body fluids and tissue. The SLOS phenotypic spectrum ranges from a mild disorder with behavioral and learning problems to a lethal disease characterized by multiple malformations. Here, we describe a newborn male with ambiguous genitalia who was diagnosed to have type II SLOS during the neonatal period. A clinical examination revealed low levels of unconjugated estriol in the maternal serum, and a variety of fetal ultrasound anomalies, including prenatal growth retardation. After birth, the infant was diagnosed to have congenital heart disease (Tetralogy of Fallot with severe pulmonary artery stenosis), cleft lip and palate, micrognathia, postaxial polydactyly, ambiguous genitalia, and cataracts. Clinical investigation revealed extremely low plasma cholesterol levels and the presence of mutation (homozygote of p.Arg352Gln) in the DHCR7 gene. The patient underwent palliative heart surgery (to widen the pulmonary artery) and received intravenous lipid supplementation. Cholesterol levels increased slightly, but not to normal values. The patient died from cardiopulmonary failure and sepsis 72 days after birth. This report provides the first description of a Korean patient with SLOS confirmed by verification of DHCR7 gene mutation and illustrates the need for early recognition and appropriate diagnosis of this disease.

Effect of guanxin no. 2 on gene variant expression profile in rats after myocardial ischemia / 中国中西医结合杂志

<p><b>OBJECTIVE</b>To study the effect of Guanxin No. 2 (GX2) on gene variant expression profile in rats after myocardial infarction (MI).</p><p><b>METHODS</b>Six SD rats were equally randomized into the sham operated group, the model group and the GX2 group, and they received gastric perfusion with water and GX2 (10 g/kg) respectively. MI model was established by ligating the left-anterior descending branch of coronary artery after 10 days of perfusion, and rats' myocardial tissue in the junction zone was assessed 24 h later for gene chip detection with DNA microarray. Then a cluster analysis was conducted, and the different expressions of key genes were verified by real-time reverse transcription-polymerase chain reaction.</p><p><b>RESULTS</b>The up-regulating gene expressions in myocardial tissue in the junction zone increased after ischemia. After GX2 intervention, the up- or down-regulating gene expressions, especially the 2 genes, all-trans-13,14-dihydroretinol saturase (AF465614) and similar to expressed sequence AW413625 (AA799328) decreased significantly. In the common genes, more genes involving activity of signal transducer presented in the model group and the GX2 group and those in the latter showed a certain specificity.</p><p><b>CONCLUSION</b>GX2 could improve the characteristics of variant gene expression profile in MI rats to a certain extent.</p>

Molecular biology and biochemistry of malarial parasite pyrimidine biosynthetic pathway.

Metabolic pathways in the malarial parasite are markedly different from the host, eg, hemoglobin, fatty acids, folate and nucleic acids. Understanding of metabolic function will illuminate new chemotherapeutic targets for drug development, including the identification of target(s) for drugs in current use. The parasite-contained pyrimidine biosynthetic pathway is essential for growth and development in the human host. Plasmodium falciparum carbonic anhydrase, producing HCO3- as a pyrimidine precursor, was identified as alpha- type and the encoded gene was cloned and sequenced. The first six enzymes, catalyzing the conversion of HCO3-, ATP, L-aspartate and L-glutamine to uridine 5'-monophosphate (UMP), were partially characterized. The genes encoding these enzymes were identified in order, from the first to the sixth step, as CPSII (carbamyl phosphate synthase II), ATC (aspartate transcarbamylase), DHO (dihydroorotase), DHOD (dihydroorotate dehydrogenase, DHOD), OPRT (orotate phosphoribosyltransferase, OPRT), and OMPDC (orotidine 5'-monophosphate decarboxylase, OMPDC). Unlike its analogous parasitic protozoan, Trypanosoma, the organization of the malarial genes was not an operon-like cluster. The CPSII, DHO and OPRT genes were conserved to bacterial counterparts, whereas the ATC, DHOD and OMPDC were mosaic variations. The data support the mosaic pyrimidine pathway in the malarial parasite. The human host had five enzymes out of the six associated into two different multifunctional proteins, in that a single gene CPSII-ATC-DHO encoded the first three enzymes, and another gene OPRT-OMPDC encoded the last two enzymes. In the malarial parasite, the CPSII and ATC were not characterized. The DHO was partially characterized in Plasmodium berghei. The DHOD was well characterized in both P. falciparum and P. berghei. It was functionally expressed in Escherichia coli. The physical and kinetic properties of the recombinant pfDHOD were similar to the native enzyme. The OPRT and OMPDC were also partially characterized. These lines of evidence indicate that the malarial pyrimidine enzymes are mono-functional forms. In addition, the enzymatic activities inter-converting uracil, uridine and UMP of the pyrimidine salvage pathway, were demonstrated, and the gene encoding uridine phosphorylase was cloned. Our results suggest that the pyrimidine enzymes are possible new drug targets.

Genes encoding chimeras of Neurospora crassa erg-3 and human TM7SF2 proteins fail to complement Neurospora and yeast sterol C-14 reductase mutants.

The human gene TM7SF2 encodes a polypeptide (SR-1) with high sequence similarity to sterol C-14 reductase, a key sterol biosynthetic enzyme in fungi, plants and mammals. In Neurospora and yeast this enzyme is encoded by the erg-3 and erg24 genes respectively. In an effort to demonstrate sterol C-14 reductase activity for SR-1 we constructed six recombinant genes coding for chimeras of the Neurospora erg-3 and SR-1 protein sequences and tested them for complementation of the Neurospora erg-3 mutant. To our surprise, all the chimeras failed to complement erg-3. A few of the chimeric proteins were also tested against the yeast erg24 mutant, but again there was no complementation. We discuss some reasons that might account for these unexpected findings.