Assessing Postnatal Mortality in Smith-Lemli-Opitz Syndrome.

Smith-Lemli-Opitz syndrome (SLOS) is a rare autosomal recessive disorder caused by pathological variants in DHCR7, resulting in a deficiency in the enzyme 7-dehydrocholesterol reductase. This results in elevated levels of cholesterol precursors and typically low cholesterol levels, leading to a range of physical and cognitive challenges. Mortality rates in infants with severe SLOS are high, due to congenital malformations. Premature death has been described in individuals with SLOS, particularly in severely affected individuals. Further research is needed to understand postnatal mortality risk factors for individuals with SLOS. Understanding these factors could improve monitoring and prevention efforts. To investigate this, we obtained death certificates from the National Death Index (NDI) database on a cohort of individuals with SLOS who were enrolled in natural history studies at the National Institutes of Health Clinical Center (NCT00001721 and NCT05047354). Analysis and comparison of this deceased cohort showed that although premature death occurs in SLOS, many individuals with SLOS survive into adulthood. We also observed the risk of postnatal mortality increasing with higher severity scores and lower initial cholesterol levels. Trial Registration: NCT00001721 and NCT05047354.

Genetic Variants in Vitamin-D Metabolism Genes (rs1155563, rs12785878 and rs10500804) among Females with Type-2 Diabetes Mellitus in Saudi Arabia.

Background & Objective: Hypovitaminosis D has shown to be linked with T2DM development and control in numerous studies. The association of SNPs in genes related to VitD metabolism with T2DM has not been sufficiently studied. Consequently, our aim in the present study was to explore the association between genetic variants in genes connected with VitD, mainly a SNP in GC (rs1155563), a SNP in DHCR7 (rs12785878) and a SNP in CYP2R1 (rs10500804) with glycaemic parameters in females with T2DM in Saudi Arabia. Methods: The cross-sectional study included 149 females (age 38-52 years) with T2DM from Jeddah, Saudi Arabia (September 2022-March 2023). Blood was extracted from the participants for biochemical tests including measuring VitD [25(OH)D] concentration, parameters of glycaemia (HbA1c, insulin, fasting glucose and insulin sensitivity indices including HOMA2-IR and HOMA2-%ß), and for genomic DNA isolation. Sanger DNA sequencing was used to screen for VitD genetic polymorphisms (rs1155563, rs12785878 and rs10500804). Results: Minor allele frequency for rs1155563C, rs12785878T and rs10500804G was 0.21, 0.23 and 0.37, respectively. Levels of 25(OH)D and glycaemic parameters as well did not show any significant difference between the genotypes of each SNP. Conclusion: This study showed lack of association of rs1155563 in GC, rs12785878 in DHCR7 and rs10500804 in CYP2R1 with VitD level primarily and with glycaemic parameters secondarily. Additional research is required to explore further other VitD genetic polymorphisms influencing T2DM which might lead consequently to genetically-based personalized management for T2DM.

Elevated cerebrospinal fluid glial fibrillary acidic protein levels in Smith-Lemli-Opitz syndrome.

Smith-Lemli-Opitz syndrome (SLOS) is a rare, multiple malformation/intellectual disability disorder caused by pathogenic variants of DHCR7. DHCR7 catalyzes the reduction of 7-dehydrocholesterol (7DHC) to cholesterol in the final step of cholesterol biosynthesis. This results in accumulation of 7DHC and a cholesterol deficiency. Although the biochemical defect is well delineated and multiple mechanisms underlying developmental defects have been explored, the post developmental neuropathological consequences of altered central nervous system sterol composition have not been studied. Preclinical studies suggest that astroglial activation may occur in SLOS. To determine if astroglial activation is present in individuals with SLOS, we quantified cerebrospinal fluid (CSF) glial fibrillary acidic protein using a Quanterix Simoa® GFAP Discovery Kit for SR-X™. Relative to an age-appropriate comparison group, we found that CSF GFAP levels were elevated 3.9-fold in SLOS (3980 ± 3732 versus 1010 ± 577 pg/ml, p = 0.0184). Simvastatin, a 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, has previously been shown to increase expression of hypomorphic DHCR7 alleles and in a placebo-controlled trial improved serum sterol levels and decreased irritability. Using archived CSF samples from that prior study, we observed a significant decrease (p = 0.0119) in CSF GFAP levels in response to treatment with simvastatin. Although further work needs to be done to understand the potential contribution of neuroinflammation to SLOS neuropathology and cognitive dysfunction, these data confirm astroglial activation in SLOS and suggest that CSF GFAP may be a useful biomarker to monitor therapeutic responses.

Smith-Lemli-Opitz Syndrome with Biallelic c.1295A>G (p.Tyr432Cys) Variant in the DHCR7 Gene in a 73-Year-Old Woman: Report of the Oldest Patient.

Introduction: Smith-Lemli-Opitz syndrome (SLOS), a genetic developmental disorder characterized by various congenital anomalies, arises from a loss of normal DHCR7 enzymatic action in cholesterol biosynthesis. This syndrome is typically marked by various congenital anomalies, including microcephaly with cognitive impairments, distinctive facial features, and syndactyly of the toes (2-3 fusion). Case Presentation: A 73-year-old woman, followed up on by the neurology clinic for the last 3 years for amnesia and movement disorders, was referred to our clinic for genetic etiology investigation. Although there were no significant dysmorphic findings on her physical examination, observations included partial syndactyly between the second and third toes of both feet, a wide forehead, and a triangular face. We used the whole-exome sequencing (WES) analysis to evaluate the patient because of their various phenotype, which included dysmorphic features, movement problems, recurrent hip dislocation, mild intellectual impairment. WES analysis revealed a homozygous missense c.1295A>G (p.Tyr432Cys) variation in DHCR7 gene. Discussion: A total of 9 patients with p.Tyr432Cys variant have been reported in the literature so far. The present case is the first patient with biallelic c.1295A>G (p.Tyr432Cys) variation in DHCR7 gene in the current literature. Diagnosing the disorder can be challenging, particularly in its milder manifestations, given the extensive range of clinical presentations. The present case is the oldest patient with SLOS reported in the relevant literature. Mild dysmorphic features, mild intellectual disability, and recurrent hip dislocation, along with the typical finding of syndactyly between the second and third toes in the foot, may indicate mild forms of SLOS.

Human Genetics of Atrial Septal Defect.

Although atrial septal defects (ASD) can be subdivided based on their anatomical location, an essential aspect of human genetics and genetic counseling is distinguishing between isolated and familiar cases without extracardiac features and syndromic cases with the co-occurrence of extracardiac abnormalities, such as developmental delay. Isolated or familial cases tend to show genetic alterations in genes related to important cardiac transcription factors and genes encoding for sarcomeric proteins. By contrast, the spectrum of genes with genetic alterations observed in syndromic cases is diverse. Currently, it points to different pathways and gene networks relevant to the dysregulation of cardiomyogenesis and ASD pathogenesis. Therefore, this chapter reflects the current knowledge and highlights stable associations observed in human genetics studies. It gives an overview of the different types of genetic alterations in these subtypes, including common associations based on genome-wide association studies (GWAS), and it highlights the most frequently observed syndromes associated with ASD pathogenesis.

The symptomatology of Attention-Deficit/Hyperactivity Disorder and the genetic control of vitamin D levels.

OBJECTIVES: Vitamin D deficiency has been associated with psychiatric disorders and behavioral phenotypes such as Attention-Deficit/Hyperactivity Disorder (ADHD). Considering that vitamin D levels are polygenic, we aim to evaluate the overall effects of its genetic architecture on symptoms of inattention, hyperactivity, and impulsivity and on the serum levels of vitamin D in two independent samples of adults, as well as the specific effects of five relevant polymorphisms in vitamin D-related genes. METHODS: We evaluated 870 subjects from an ADHD sample (407 cases and 463 controls) and 319 subjects from an academic community (nutrigenetic sample). Vitamin D serum levels were obtained through Elisa test and genetic data by TaqMan™ allelic discrimination and Infinium PsychArray-24 BeadChip genotyping. Polygenic Scores (PGS) were calculated on PRSice2 based on the latest GWAS for Vitamin D and statistical analyses were conducted at Plink and SPSS software. RESULTS: Vitamin D PGSs were associated with inattention in the ADHD sample and with hyperactivity when inattention symptoms were included as covariates. In the nutrigenetic sample, CYP2R1 rs10741657 and DHCR7 rs12785878 were nominally associated with impulsivity and hyperactivity, respectively, and both with vitamin D levels. In the clinical sample, RXRG rs2134095 was associated with impulsivity. DISCUSSION: Our findings suggest a shared genetic architecture between vitamin D levels and ADHD symptoms, as evidenced by the associations observed with PGS and specific genes related to vitamin D levels. Interestingly, differential effects for vitamin D PGS were found in inattention and hyperactivity, which should be considered in further studies involving ADHD.

Chemical Inhibition of Sterol Biosynthesis.

Cholesterol is an essential molecule of life, and its synthesis can be inhibited by both genetic and nongenetic mechanisms. Hundreds of chemicals that we are exposed to in our daily lives can alter sterol biosynthesis. These also encompass various classes of FDA-approved medications, including (but not limited to) commonly used antipsychotic, antidepressant, antifungal, and cardiovascular medications. These medications can interfere with various enzymes of the post-lanosterol biosynthetic pathway, giving rise to complex biochemical changes throughout the body. The consequences of these short- and long-term homeostatic disruptions are mostly unknown. We performed a comprehensive review of the literature and built a catalogue of chemical agents capable of inhibiting post-lanosterol biosynthesis. This process identified significant gaps in existing knowledge, which fall into two main areas: mechanisms by which sterol biosynthesis is altered and consequences that arise from the inhibitions of the different steps in the sterol biosynthesis pathway. The outcome of our review also reinforced that sterol inhibition is an often-overlooked mechanism that can result in adverse consequences and that there is a need to develop new safety guidelines for the use of (novel and already approved) medications with sterol biosynthesis inhibiting side effects, especially during pregnancy.

DHCR7 links cholesterol synthesis with neuronal development and axonal integrity.

The DHCR7 enzyme converts 7-DHC into cholesterol. Mutations in DHCR7 can block cholesterol production, leading to abnormal accumulation of 7-DHC and causing Smith-Lemli-Opitz syndrome (SLOS). SLOS is an autosomal recessive disorder characterized by multiple malformations, including microcephaly, intellectual disability, behavior reminiscent of autism, sleep disturbances, and attention-deficit/hyperactivity disorder (ADHD)-like hyperactivity. Although 7-DHC affects neuronal differentiation in ex vivo experiments, the precise mechanism of SLOS remains unclear. We generated Dhcr7 deficient (dhcr7-/-) zebrafish that exhibited key features of SLOS, including microcephaly, decreased neural stem cell pools, and behavioral phenotypes similar to those of ADHD-like hyperactivity. These zebrafish demonstrated compromised myelination, synaptic anomalies, and neurotransmitter imbalances. The axons of the dhcr7-/- zebrafish showed increased lysosomes and attenuated autophagy, suggesting that autophagy-related neuronal homeostasis is disrupted.

Identification and validation of DHCR7 as a diagnostic biomarker involved in the proliferation and mitochondrial function of breast cancer.

BACKGROUND: Energy metabolism has a complex intersection with pathogenesis and development of breast cancer (BC). This allows for the possibility of identifying energy-metabolism-related genes (EMRGs) as novel prognostic biomarkers for BC. 7-dehydrocholesterol reductase (DHCR7) is a key enzyme of cholesterol biosynthesis involved in many cancers, and in this paper, we investigate the effects of DHCR7 on the proliferation and mitochondrial function of BC. METHODS: EMRGs were identified from the Gene Expression Omnibus (GEO) and MSigDB databases using bioinformatics methods. Key EMRGs of BC were then identified and validated by functional enrichment analysis, interaction analysis, weighted gene co-expression network analysis (WGCNA), least absolute shrinkage and selection operator (LASSO) regression, Cox analysis, and immune infiltration. Western blot, qRT-PCR, immunohistochemistry (IHC), MTT assay, colony formation assay and flow cytometry assay were then used to analyze DHCR7 expression and its biological effects on BC cells. RESULTS: We identified 31 EMRGs in BC. These 31 EMRGs and related transcription factors (TFs), miRNAs, and drugs were enriched in glycerophospholipid metabolism, glycoprotein metabolic process, breast cancer, and cell cycle. Crucially, DHCR7 was a key EMRG in BC identified and validated by WGCNA, LASSO regression and receiver operating characteristic (ROC) curve analysis. High DHCR7 expression was significantly associated with tumor immune infiltration level, pathological M, and poor prognosis in BC. In addition, DHCR7 knockdown inhibited cell proliferation, induced apoptosis and affected mitochondrial function in BC cells. CONCLUSIONS: DHCR7 was found to be a key EMRG up-regulated in BC cells. This study is the first to our knowledge to report that DHCR7 acts as an oncogene in BC, which might become a novel therapeutic target for BC patients.

Inhibition of pseudorabies virus replication via upregulated interferon response by targeting 7-dehydrocholesterol reductase.

Pseudorabies virus (PRV) is an alpha-herpesvirus capable of infecting a range of animal species, particularly its natural host, pigs, resulting in substantial economic losses for the swine industry. Recent research has shed light on the significant role of cholesterol metabolism in the replication of various viruses. However, the specific role of cholesterol metabolism in PRV infection remains unknown. Here, we demonstrated that the expression of 7-dehydrocholesterol reductase (DHCR7) is upregulated following PRV infection, as evidenced by the proteomic analysis. Subsequently, we showed that DHCR7 plays a crucial role in promoting PRV replication by converting 7-dehydrocholesterol (7-DHC) into cholesterol, leading to increased cellular cholesterol levels. Importantly, DHCR7 inhibits the phosphorylation of interferon regulatory factor 3 (IRF3), resulting in reduced levels of interferon-beta (IFN-ß) and interferon-stimulated genes (ISGs). Finally, we revealed that the DHCR7 inhibitor, trans-1,4-bis(2-chlorobenzylaminomethyl) cyclohexane dihydrochloride (AY9944), significantly suppresses PRV replication both in vitro and in vivo. Taken together, the study has established a connection between cholesterol metabolism and PRV replication, offering novel insights that may guide future approaches to the prevention and treatment of PRV infections.

Cholic acid increases plasma cholesterol in Smith-Lemli-Opitz syndrome: A pilot study.

Background: Smith-Lemli-Opitz syndrome (SLOS) is an inherited disorder of cholesterol biosynthesis associated with congenital malformations, growth delay, intellectual disability and behavior problems. SLOS is caused by bi-allelic mutations in DHCR7, which lead to reduced activity of 7-dehydrocholesterol reductase that catalyzes the last step in cholesterol biosynthesis. Symptoms of SLOS are thought to be due to cholesterol deficiency and accumulation of its precursor 7-dehydrocholesterol (7-DHC) and 8-dehydrocholesterol (8-DHC), and toxic oxysterols. Therapy for SLOS often includes dietary cholesterol supplementation, but lipids are poorly absorbed from the diet, possibly due to impaired bile acid synthesis. We hypothesized that bile acid supplementation with cholic acid would improve dietary cholesterol absorption and raise plasma cholesterol levels. Methods: Twelve SLOS subjects (10 M, 2F, ages 2-27 years) who had plasma cholesterol ≤125 mg/dL were treated with cholic acid (10 mg/kg/day) divided twice daily for 2 months. Plasma cholesterol, 7-DHC and 8-DHC were measured by GC-MS. Oxysterols were measured by ultra-high-performance LC-MS/MS. Data were analyzed using paired t-tests. Results: At baseline, plasma cholesterol was 75 ± 24 mg/dL (mean ± SD; range 43-125, n = 12). After 2 months on cholic acid, mean plasma cholesterol increased to 97 ± 29 mg/dL (p = 0.011). Eleven of 12 subjects showed an increase in plasma cholesterol that varied from 3.8% to 85.7% (mean 38.7 ± 23.3%). 7-Hydroxycholesterol decreased by 20.6% on average (p = 0.013) but no significant changes were seen in 7-DHC or 8-DHC. Mean body weight tended to increase (3.6% p = 0.069). Subjects tolerated cholic acid well and experienced no drug-related adverse events. Conclusions: In this pilot study, cholic acid supplementation was well tolerated and safe and resulted in an increase in plasma cholesterol in most SLOS subjects. Further controlled longitudinal studies are needed to look for the sustainability of the biochemical effect and possible clinical benefits.

Effect of DHCR7 on adipocyte differentiation in goats.

Cholesterol is regarded as a signaling molecule in regulating the metabolism and function of fat cells, in which 7-Dehydrocholesterol reductase (DHCR7) is a key enzyme that catalyzes the conversion of 7-dehydrocholesterol to cholesterol, however, the exact function of DHCR7 in goat adipocytes remains unknown. Here, the effect of DHCR7 on the formation of subcutaneous and intramuscular fat in goats was investigated in vitro, and the result indicated that the mRNA level of DHCR7 showed a gradual downward trend in subcutaneous adipogenesis, but an opposite trend in intramuscular adipogenesis. In the process of subcutaneous preadipocytes differentiation, overexpression of DHCR7 inhibited the expression of adipocytes differentiation marker genes (CEBP/α, CEBP/ß, SREBP1 and AP2), lipid metabolism-related genes (AGPAT6, FASN, SCD1 and LPL), and the lipid accumulation. However, in intramuscular preadipocyte differentiation, DHCR7 overexpression showed a promoting effect on adipocyte differentiation marker genes (CEBP/α, CEBP/ß, PPARγ and SREBP1) and lipid metabolism-related genes (GPAM, AGPAT6, DGAT1 and SCD1) expression, and on lipid accumulation. In summary, our work demonstrated that DHCR7 played an important role in regulating adipogenic differentiation and lipid metabolism in preadipocytes in goats, which is of great significance for uncovering the underlying molecular mechanism of adipocyte differentiation and improving goat meat quality.

Investigating the Diagnostic and Therapeutic Potential of SREBF2-Related Lipid Metabolism Genes in Colon Cancer.

Purpose: Colon cancer is one of the leading causes of death worldwide, and screening of effective molecular markers for the diagnosis is prioritised for prevention and treatment. This study aimed to investigate the diagnostic and predictive potential of genes related to the lipid metabolism pathway, regulated by a protein called sterol-regulatory element-binding transcription Factor 2 (SREBF2), for colon cancer and patient outcomes. Methods: We used machine-learning algorithms to identify key genes associated with SREBF2 in colon cancer based on a public database. A nomogram was created to assess the diagnostic value of these genes and validated in the Cancer Genome Atlas. We also analysed the relationship between these genes and the immune microenvironment of colon tumours, as well as the correlation between gene expression and clinicopathological characteristics and prognosis in the China Medical University (CMU) clinical cohort. Results: Three genes, 7-dehydrocholesterol reductase (DHCR7), hydroxysteroid 11-beta dehydrogenase 2 (HSD11B2), and Ral guanine nucleotide dissociation stimulator-like 1 (RGL1), were identified as hub genes related to SREBF2 and colon cancer. Using the TCGA dataset, receiver operating characteristic curve analysis showed the area under the curve values of 0.943, 0.976, and 0.868 for DHCR7, HSD11B2, and RGL1, respectively. In the CMU cohort, SREBF2 and DHCR7 expression levels were correlated with TNM stage and tumour invasion depth (P < 0.05), and high DHCR7 expression was related to poor prognosis of colon cancer (P < 0.05). Furthermore, DHCR7 gene expression was positively correlated with the abundance of M0 and M1 macrophages and inversely correlated with the abundance of M2 macrophages, suggesting that the immune microenvironment may play a role in colon cancer surveillance. There was a correlation between SREBF2 and DHCR7 expression across cancers in the TCGA database. Conclusion: This study highlights the potential of DHCR7 as a diagnostic marker and therapeutic target for colon cancer.

Chronic Aripiprazole and Trazodone Polypharmacy Effects on Systemic and Brain Cholesterol Biosynthesis.

The concurrent use of several medications is a common practice in the treatment of complex psychiatric conditions. One such commonly used combination is aripiprazole (ARI), an antipsychotic, and trazodone (TRZ), an antidepressant. In addition to their effects on dopamine and serotonin systems, both of these compounds are inhibitors of the 7-dehydrocholesterol reductase (DHCR7) enzyme. To evaluate the systemic and nervous system distribution of ARI and TRZ and their effects on cholesterol biosynthesis, adult mice were treated with both ARI and TRZ for 21 days. The parent drugs, their metabolites, and sterols were analyzed in the brain and various organs of mice using LC-MS/MS. The analyses revealed that ARI, TRZ, and their metabolites were readily detectable in the brain and organs, leading to changes in the sterol profile. The levels of medications, their metabolites, and sterols differed across tissues with notable sex differences. Female mice showed higher turnover of ARI and more cholesterol clearance in the brain, with several post-lanosterol intermediates significantly altered. In addition to interfering with sterol biosynthesis, ARI and TRZ exposure led to decreased ionized calcium-binding adaptor molecule 1 (IBA1) and increased DHCR7 protein expression in the cortex. Changes in sterol profile have been also identified in the spleen, liver, and serum, underscoring the systemic effect of ARI and TRZ on sterol biosynthesis. Long-term use of concurrent ARI and TRZ warrants further studies to fully evaluate the lasting consequences of altered sterol biosynthesis on the whole body.

Integrated multi-dimensional analysis highlights DHCR7 mutations involving in cholesterol biosynthesis and contributing therapy of gastric cancer.

BACKGROUND: Genetic background plays an important role in the occurrence and development of gastric cancer (GC). With the application of genome-wide association study (GWAS), an increasing number of tumor susceptibility genes in gastric cancer have been discovered. While little of them can be further applicated in clinical diagnosis and treatment due to the lack of in-depth analysis. METHODS: A GWAS of peripheral blood leukocytes from GC patients was performed to identify and obtain genetic background data. In combination with a clinical investigation, key SNP mutations and mutated genes were screened. Via in vitro and in vivo experiments, the function of the mutated gene was verified in GC. Via a combination of molecular function studies and amino acid network analysis, co-mutations were discovered and further identified as potential therapeutic targets. RESULTS: At the genetic level, the G allele of rs104886038 in DHCR7 was a protective factor identified by the GWAS. Clinical investigation showed that patients with the rs104886038 A/G genotype, age ≥ 60, smoking ≥ 10 cigarettes/day, heavy drinking and H. pylori infection were independent risk factors for GC, with odds ratios of 12.33 (95% CI, 2.10 ~ 72.54), 20.42 (95% CI, 2.46 ~ 169.83), and 11.39 (95% CI, 1.82 ~ 71.21), respectively. Then molecular function studies indicated that DHCR7 regulated cell proliferation, migration, and invasion as well as apoptosis resistance via cellular cholesterol biosynthesis pathway. Further amino acid network analysis based on the predicted structure of DHCR7 and experimental verification indicated that rs104886035 and rs104886038 co-mutation reduced the stability of DHCR7 and induced its degradation. DHCR7 mutation suppressed the malignant behaviour of GC cells and induced apoptosis via inhibition on cell cholesterol biosynthesis. CONCLUSION: In this work, we provided a comprehensive multi-dimensional analysis strategy which can be applied to in-depth exploration of GWAS data. DHCR7 and its mutation sites identified by this strategy are potential theratic targets of GC via inhibition of cholesterol biosynthesis.

Zika virus non-structural protein 4B interacts with DHCR7 to facilitate viral infection.

Zika virus (ZIKV) evolves non-structural proteins to evade immune response and ensure efficient replication in the host cells. Cholesterol metabolic enzyme 7-dehydrocholesterol reductase (DHCR7) was recently reported to impact innate immune responses in ZIKV infection. However, the vital non-structural protein and mechanisms involved in DHCR7-mediated viral evasion are not well elucidated. In this study, we demonstrated that ZIKV infection facilitated DHCR7 expression. Notably, the upregulated DHCR7 in turn facilitated ZIKV infection and blocking DHCR7 suppressed ZIKV infection. Mechanically, ZIKV non-structural protein 4B (NS4B) interacted with DHCR7 to induce DHCR7 expression. Moreover, DHCR7 inhibited TANK-binding kinase 1 (TBK1) and interferon regulatory factor 3 (IRF3) phosphorylation, which resulted in the reduction of interferon-beta (IFN-ß) and interferon-stimulated genes (ISGs) productions. Therefore, we propose that ZIKV NS4B binds to DHCR7 to repress TBK1 and IRF3 activation, which in turn inhibits IFN-ß and ISGs, and thereby facilitating ZIKV evasion. This study broadens the insights on how viral non-structural proteins antagonize innate immunity to facilitate viral infection via cholesterol metabolic enzymes and intermediates.

Characterization and potential function of 7-dehydrocholesterol reductase (dhcr7) and lathosterol 5-desaturase (sc5d) in Cynoglossus semilaevis sexual size dimorphism.

The typical sexual size dimorphism (SSD) phenomenon of Chinese tongue sole (Cynoglossus semilaevis) seriously restricts the sustainable development of the fishing industry. Previous transcriptome analysis has found a close relationship between the steroid biosynthesis and C. semilaevis SSD. The 7-dehydrocholesterol reductase (dhcr7) and lathosterol 5-desaturase (sc5d) are two genes in the steroid biosynthesis pathway, playing important roles in lipid synthesis, cellular metabolism, and growth. The present study assessed their roles in the mechanism of C. semilaevis SSD. The quantitative polymerase chain reaction (qPCR) results showed that C. semilaevis dhcr7 was mainly expressed in female livers, and C. semilaevis sc5d was highly expressed in female livers and gonads. Dual-luciferase experiment showed that dhcr7 and sc5d promoters had strong transcriptional activity. The transcription factors E2F transcription factor 1 (E2F1), and CCAAT enhancer binding protein alpha (C/EBPα) significantly regulated the transcriptional activity of dhcr7 and sc5d promoters, respectively. Furthermore, small interfering RNA (siRNA) knockdown results showed that expression levels of several genes [SREBF chaperone (scap), membrane-bound transcription factor peptidase, site 1 (mbtps1), fatty acid synthase (fasn), sonic hedgehog (shh), bone morphogenetic protein 2b (bmp2b) and AKT serine/threonine kinase 1 (akt1)] were suppressed. Protein subcellular localization results indicated that Dhcr7 and Sc5d were both specifically distributed in the cytoplasm, with co-localization been observed. The present study provides evidence that dhcr7 and sc5d might regulate C. semilaevis sexual size dimorphism by involving in energy homeostasis and cell cycle, or by affecting PI3K-Akt and Shh signaling pathways. The detailed roles of these steroid biosynthesis genes regulating C. semilaevis SSD needed more information.

Targeting 7-dehydrocholesterol reductase against EV-A71 replication by upregulating interferon response.

Recent studies have shown a close link between viral infections and cholesterol metabolism. Here, we reported that 7-dehydrocholesterol reductase (DHCR7), a terminal enzyme for catalyzing cholesterol synthesis in the Kandutsch-Russell pathway, is harnessed by enterovirus A71 (EV-A71) benefitting for its replication. Overexpression of DHCR7 resulted in upregulating of EV-A71 replication, while the S14A mutation, which reduces DHCR7 enzyme activity, has no effect on EV-A71 replication. Knockdown of DHCR7 expression with small interfering RNA (siRNA) or enzyme activity inhibition with pharmacological inhibitor AY9944 could significantly inhibit EV-A71 replication. Adding cholesterol to DHCR7 knockdown cells or AY9944-treated cells could rescue EV-A71 replication. More importantly, prophylactic administration of AY9944 effectively protected mice from lethal EV-A71 infection. In addition, the natural cholesterol precursor 7-dehydrocholesterol (7-DHC), which is converted to cholesterol by DHCR7, has a similar effect against EV-A71 infection. Mechanistically, AY9944 or 7-DHC treatment can specifically promote IRF3 phosphorylation to activate interferon response. Moreover, AY9944 effectively cleared coxsackievirus B3 (CVB3) and coxsackievirus A16 (CVA16) infections in vitro. In conclusion, pharmacological modulation of DHCR7 might provide a chance for treatment of enterovirus infection, including EV-A71.

Sterol dysregulation in Smith-Lemli-Opitz syndrome causes astrocyte immune reactivity through microglia crosstalk.

Owing to the need for de novo cholesterol synthesis and cholesterol-enriched structures within the nervous system, cholesterol homeostasis is critical to neurodevelopment. Diseases caused by genetic disruption of cholesterol biosynthesis, such as Smith-Lemli-Opitz syndrome, which is caused by mutations in 7-dehydrocholesterol reductase (DHCR7), frequently result in broad neurological deficits. Although astrocytes regulate multiple neural processes ranging from cell migration to network-level communication, immunological activation of astrocytes is a hallmark pathology in many diseases. However, the impact of DHCR7 on astrocyte function and immune activation remains unknown. We demonstrate that astrocytes from Dhcr7 mutant mice display hallmark signs of reactivity, including increased expression of glial fibrillary acidic protein (GFAP) and cellular hypertrophy. Transcript analyses demonstrate extensive Dhcr7 astrocyte immune activation, hyper-responsiveness to glutamate stimulation and altered calcium flux. We further determine that the impacts of Dhcr7 are not astrocyte intrinsic but result from non-cell-autonomous effects of microglia. Our data suggest that astrocyte-microglia crosstalk likely contributes to the neurological phenotypes observed in disorders of cholesterol biosynthesis. Additionally, these data further elucidate a role for cholesterol metabolism within the astrocyte-microglia immune axis, with possible implications in other neurological diseases.

Metoprolol Inhibits Developmental Brain Sterol Biosynthesis in Mice.

De novo sterol synthesis is a critical homeostatic mechanism in the brain that begins during early embryonic development and continues throughout life. Multiple medications have sterol-biosynthesis-inhibiting side effects, with potentially detrimental effects on brain health. Using LC-MS/MS, we investigated the effects of six commonly used beta-blockers on brain sterol biosynthesis in vitro using cell lines. Two beta-blockers, metoprolol (MTP) and nebivolol, showed extreme elevations of the highly oxidizable cholesterol precursor 7-dehydrocholesterol (7-DHC) in vitro across multiple cell lines. We followed up on the MTP findings using a maternal exposure model in mice. We found that 7-DHC was significantly elevated in all maternal brain regions analyzed as well as in the heart, liver and brain of the maternally exposed offspring. Since DHCR7-inhibiting/7-DHC elevating compounds can be considered teratogens, these findings suggest that MTP utilization during pregnancy might be detrimental for the development of offspring, and alternative beta-blockers should be considered.