Explore the vast range of titles available.

Garrod’s concept of ‘chemical individuality’ has contributed to comprehension of the molecular origins of human diseases. Untargeted high-throughput metabolomic technologies provide an in-depth snapshot of human metabolism at scale. We studied the genetic architecture of the human plasma metabolome using 913 metabolites assayed in 19,994 individuals and identified 2,599 variant–metabolite associations ( P  < 1.25 × 10 −11 ) within 330 genomic regions, with rare variants (minor allele frequency ≤ 1%) explaining 9.4% of associations. Jointly modeling metabolites in each region, we identified 423 regional, co-regulated, variant–metabolite clusters called genetically influenced metabotypes. We assigned causal genes for 62.4% of these genetically influenced metabotypes, providing new insights into fundamental metabolite physiology and clinical relevance, including metabolite-guided discovery of potential adverse drug effects ( DPYD and SRD5A2 ). We show strong enrichment of inborn errors of metabolism-causing genes, with examples of metabolite associations and clinical phenotypes of non-pathogenic variant carriers matching characteristics of the inborn errors of metabolism. Systematic, phenotypic follow-up of metabolite-specific genetic scores revealed multiple potential etiological relationships. Analyses of the genetic architecture of the human plasma metabolome in two large population-based cohorts identify associations between genetically determined metabolite levels and health.

Human steroid 5α-reductase 2 (SRD5A2) is an integral membrane enzyme in steroid metabolism and catalyzes the reduction of testosterone to dihydrotestosterone. Mutations in the SRD5A2 gene have been linked to 5α-reductase deficiency and prostate cancer. Finasteride and dutasteride, as SRD5A2 inhibitors, are widely used antiandrogen drugs for benign prostate hyperplasia. The molecular mechanisms underlying enzyme catalysis and inhibition for SRD5A2 and other eukaryotic integral membrane steroid reductases remain elusive due to a lack of structural information. Here, we report a crystal structure of human SRD5A2 at 2.8 Å, revealing a unique 7-TM structural topology and an intermediate adduct of finasteride and NADPH as NADP-dihydrofinasteride in a largely enclosed binding cavity inside the transmembrane domain. Structural analysis together with computational and mutagenesis studies reveal the molecular mechanisms of the catalyzed reaction and of finasteride inhibition involving residues E57 and Y91. Molecular dynamics simulation results indicate high conformational dynamics of the cytosolic region that regulate NADPH/NADP + exchange. Mapping disease-causing mutations of SRD5A2 to our structure suggests molecular mechanisms for their pathological effects. Our results offer critical structural insights into the function of integral membrane steroid reductases and may facilitate drug development. Human steroid 5α-reductase 2 (SRD5A2) is an integral membrane enzyme and catalyzes 5α-reduction of testosterone to dihydrotestosterone. Structural analysis accompanied by computational and mutagenesis studies reveal the mechanisms of catalysis and inhibition by clinically relevant drugs targeting SRD5A2.

Brassinosteroids (BRs) are plant hormones that regulate growth and development. They share structural similarities with animal steroids, which are decisive factors of sex determination. BRs are known to regulate morphogenesis and environmental stress responses, but their involvement in sex determination in plants has been only speculative. We show that BRs control sex determination in maize revealed through characterization of the classical dwarf mutant nana plant1 (na1), which also feminizes male flowers. na1 plants carry a loss-of-function mutation in a DET2 homolog—a gene in the BR biosynthetic pathway. The mutant accumulates the DET2-specific substrate (24R)-24-methyl-cholest-4-en-3-one with a concomitant decrease of downstream BR metabolites. Treatment of wild-type maize plants with BR biosynthesis inhibitors completely mimicked both dwarf and tasselseed phenotypes of na1 mutants. Tissue-specific na1 expression in anthers throughout their development supports the hypothesis that BRs promote masculinity of the male inflorescence. These findings suggest that, in the monoecious plant maize, BRs have been coopted to perform a sex determination function not found in plants with bisexual flowers.

Steroid hormones are essential in stress response, immune system regulation, and reproduction in mammals. Steroids with 3-oxo-Δ 4 structure, such as testosterone or progesterone, are catalyzed by steroid 5α-reductases (SRD5As) to generate their corresponding 3-oxo-5α steroids, which are essential for multiple physiological and pathological processes. SRD5A2 is already a target of clinically relevant drugs. However, the detailed mechanism of SRD5A-mediated reduction remains elusive. Here we report the crystal structure of PbSRD5A from Proteobacteria bacterium , a homolog of both SRD5A1 and SRD5A2, in complex with the cofactor NADPH at 2.0 Å resolution. PbSRD5A exists as a monomer comprised of seven transmembrane segments (TMs). The TM1-4 enclose a hydrophobic substrate binding cavity, whereas TM5-7 coordinate cofactor NADPH through extensive hydrogen bonds network. Homology-based structural models of HsSRD5A1 and -2, together with biochemical characterization, define the substrate binding pocket of SRD5As, explain the properties of disease-related mutants and provide an important framework for further understanding of the mechanism of NADPH mediated steroids 3-oxo-Δ 4 reduction. Based on these analyses, the design of therapeutic molecules targeting SRD5As with improved specificity and therapeutic efficacy would be possible. Steroid 5α-reductase 2 (SRD5A2), a testosterone metabolism enzyme, is implicated in human disease. Structural and biochemical analyses of PbSRD5A, a bacterial homolog, reveal SRD5A2 substrate binding pocket and provide framework for the design of new drugs targeting this enzyme.

Background Nucleotide sequence can be translated in three reading frames producing distinct protein products. Many examples of RNA translation in two reading frames (dual coding) have been identified so far. Results We report translation of mRNA transcripts derived from SRD5A1 locus in all three reading frames that result in the synthesis of long polypeptides. This occurs due to initiation at three nearby AUG codons occurring in all three reading frames. Only one of the three proteoforms contains the conserved catalytical domain of SRD5A1 produced either from the second or the third AUG codon depending on the transcript. Paradoxically, ribosome profiling data and expression reporters indicate that the most efficient translation would produce catalytically inactive polypeptide. While phylogenetic analysis suggests that the long triple decoding region is specific to primates, occurrence of nearby AUGs in all three reading frames is ancestral to placental mammals. This suggests that their evolutionary significance belongs to regulation of translation rather than biological role of their products. By analysing multiple publicly available ribosome profiling data and with gene expression assays carried out in different cellular environments, we show that relative expression of these proteoforms is mutually dependent and varies across environments supporting this conjecture. We show that a remarkable feature of triple decoding is its resistance to frameshift causing variants with apparent implications to clinical interpretation of genomic sequence variants. Conclusions We argue for the importance of identification, characterisation and annotation of productive RNA translation irrespective of the presumed biological roles of its products.

The drug abiraterone is converted to Δ 4 -abiraterone (D4A) in mice and patients with prostate cancer, which has more potent anti-tumour activity and may lead to more effective therapies. Alternatives to abiraterone in prostate cancer Abiraterone has been designed as a drug to treat patients with co-called castration-resistant prostate cancer — cancers that don't respond to androgen antagonists. Abiraterone works instead by blocking the formation of androgens via inhibition of the enzyme CYP17A1, a key step in the biosynthesis of testosterone and other androgens. In a new twist to these findings, Nima Sharifi and colleagues now show that abiraterone is itself metabolized in prostate tumours, giving rise to D4A which inhibits several enzymes in the androgen synthesis pathway including CYP17A1 and also antagonizes the androgen receptor. D4A has more potent anti-tumour activity in animal models, and may lead to more efficient therapies, in particular in the light of certain restrictions to the availability of abiraterone. Prostate cancer resistance to castration occurs because tumours acquire the metabolic capability of converting precursor steroids to 5α-dihydrotestosterone (DHT), promoting signalling by the androgen receptor and the development of castration-resistant prostate cancer 1 , 2 , 3 . Essential for resistance, DHT synthesis from adrenal precursor steroids or possibly from de novo synthesis from cholesterol commonly requires enzymatic reactions by 3β-hydroxysteroid dehydrogenase (3βHSD), steroid-5α-reductase (SRD5A) and 17β-hydroxysteroid dehydrogenase (17βHSD) isoenzymes 4 , 5 . Abiraterone, a steroidal 17α-hydroxylase/17,20-lyase (CYP17A1) inhibitor, blocks this synthetic process and prolongs survival 6 , 7 . We hypothesized that abiraterone is converted by an enzyme to the more active Δ 4 -abiraterone (D4A), which blocks multiple steroidogenic enzymes and antagonizes the androgen receptor, providing an additional explanation for abiraterone’s clinical activity. Here we show that abiraterone is converted to D4A in mice and patients with prostate cancer. D4A inhibits CYP17A1, 3βHSD and SRD5A, which are required for DHT synthesis. Furthermore, competitive androgen receptor antagonism by D4A is comparable to the potent antagonist enzalutamide. D4A also has more potent anti-tumour activity against xenograft tumours than abiraterone. Our findings suggest an additional explanation—conversion to a more active agent—for abiraterone’s survival extension. We propose that direct treatment with D4A would be more clinically effective than abiraterone treatment.

Background Disorders of sex development (DSDs) exhibit high genetic and phenotypic heterogeneity, and genotype–phenotype correlations are not fully understood. 5α-Reductase type 2 (5α-RD2) deficiency, a common form of DSD, is caused by SRD5A2 inactivation. This study investigated the role of SRD5A2 haplotypes in DSD, focusing on their corresponding phenotypes, structural changes and impacts on enzyme activity. Methods This study enrolled 216 individuals with DSD who underwent genetic analysis and 2,794 controls. Linkage disequilibrium analysis was performed in individuals with 5α-RD2 deficiency to identify SRD5A2 haplotypes, and haplotype frequencies were analysed across cohorts. The clinical manifestations of individuals with different SRD5A2 haplotypes were characterized. Structural predictions were employed to investigate the impacts of haplotypes on the 5α-RD2 structure and interactions with ligands. Functionally, kinetic assays were conducted to validate the effects of different haplotypes on enzyme activity. Results A SRD5A2 haplotype composed of c.265C > G and c.680G > A (Hap3: G-A) was identified, and the haplotype frequency was 64.71% in individuals with 5α-RD2 deficiency, 2.59% and 1.22% in non-5α-RD2 deficiency DSD cases without or with known DSD-related gene variants, respectively, and 1.57% in in-house controls. Globally, Hap3: G-A was enriched in southern Chinese individuals and showed high population differentiation, indicating a potential founder effect of the haplotype. The majority of homozygotes of Hap3: G-A presented microphallus, and nearly half of them manifested isolated microphallus. Structurally, Hap3: G-A was predicted to result in an increase in the solvent-accessible surface area (10.72 Å 2 ), a redistribution of hydrogen bonds within 5α-RD2, and a loss of key hydrogen bonds with NADPH. Functionally, kinetic assays showed that the catalytic efficiency of the enzyme encoded by Hap3: G-A was between that of Hap1: G-G and that of Hap2: C-A. Conclusions Hap3: G-A, which is prevalent in individuals with 5α-RD2 deficiency, suggests a potential founder effect. Structurally, compared with other haplotypes, Hap3: G-A seems to have a combined effect on the structure and interaction of 5α-RD2, rather than have merely additive effects of its constituent variants. Functionally, kinetic assays suggested a hypomorphic effect of Hap3: G-A. These findings provide valuable insights for understanding genotype–phenotype correlations, genetic counselling, early intervention and clinical management of individuals with 5α-RD2 deficiency or even other DSDs. Highlights On the basis of 216 DSD individuals and 2,794 controls, a novel SRD5A2 haplotype (Hap3: G-A), which is composed of common variants and is especially prevalent in DSD patients with 5α-RD2 deficiency, was identified, indicating the potential founder effect of Hap3: G-A. The majority of 5α-RD2 deficiency individuals with homozygous Hap3: G-A presented microphallus. Three-dimensional structure and model construction predicted that Hap3: G-A resulted in an increase in the solvent-accessible surface area, redistribution of hydrogen bonds within 5α-RD2, and loss of key hydrogen bonds with NADPH. Functionally, kinetic assays showed that the catalytic efficiency of the enzyme encoded by Hap3: G-A was between those of Hap1: G-G and Hap2: C-A, suggesting a hypomorphic effect of this haplotype. Plain Language Summary Individuals with disorders of sex development (DSDs) present variable genotypes and phenotypes, and the genotype–phenotype correlation remains poorly understood. 5α-Reductase type 2 (5α-RD2) deficiency, a common form of DSD, is caused by SRD5A2 inactivation. In this study, genetic testing and analysis were performed in 216 individuals with DSD and 2,794 non-DSD controls. A novel SRD5A2 haplotype (Hap3: G-A) was identified, and the haplotype frequency was 64.71% in individuals with 5α-RD2 deficiency, 2.59% and 1.22% in non-5α-RD2 deficiency DSD cases without or with known DSD-related gene variants, respectively, and 1.57% in in-house controls. Globally, Hap3: G-A was enriched in southern Chinese individuals and showed high population differentiation, indicating a potential founder effect of the haplotype. Analyzing the phenotype spectrum of individuals with 5α-RD2 deficiency, we found that the majority of homozygotes of Hap3: G-A presented microphallus, and nearly half of them manifested isolated microphallus. Structurally, Hap3: G-A was predicted to result in an increase in the solvent-accessible surface area, the redistribution of hydrogen bonds within 5α-RD2, and the loss of key hydrogen bonds with NADPH. Compared with other haplotypes, Hap3: G-A seemed to have a combined effect on the structure and interaction of 5α-RD2, rather than simply additive effects of its constituent variants. Functionally, kinetic assays showed that the catalytic efficiency of the enzyme encoded by Hap3: G-A was between that of Hap1: G-G and that of Hap2: C-A, suggesting a hypomorphic effect of this haplotype. These findings provide valuable insights for understanding genotype–phenotype correlations, genetic counselling, early intervention and clinical management of individuals with 5α-RD2 deficiency or even other DSDs.

Mild exercise activates hippocampal neurons through the glutamatergic pathway and also promotes adult hippocampal neurogenesis (AHN). We hypothesized that such exercise could enhance local androgen synthesis and cause AHN because hippocampal steroid synthesis is facilitated by activated neurons via N -methyl- D -aspartate receptors. Here we addressed this question using a mild-intense treadmill running model that has been shown to be a potent AHN stimulator. A mass-spectrometric analysis demonstrated that hippocampal dihydrotestosterone increased significantly, whereas testosterone levels did not increase significantly after 2 wk of treadmill running in both orchidectomized (ORX) and sham castrated (Sham) male rats. Furthermore, analysis of mRNA expression for the two isoforms of 5α-reductases (srd5a1 , srd5a2) and for androgen receptor (AR) revealed that both increased in the hippocampus after exercise, even in ORX rats. All rats were injected twice with 5′-bromo-2′deoxyuridine (50 mg/kg body weight, i.p.) on the day before training. Mild exercise significantly increased AHN in both ORX and Sham rats. Moreover, the increase of doublecortin or 5′-bromo-2′deoxyuridine/NeuN-positive cells in ORX rats was blocked by s.c. flutamide, an AR antagonist. It was also found that application of an estrogen receptor antagonist, tamoxifen, did not suppress exercise-induced AHN. These results support the hypothesis that, in male animals, mild exercise enhances hippocampal synthesis of dihydrotestosterone and increases AHN via androgenenic mediation.

In the majority of cases, advanced prostate cancer responds initially to androgen deprivation therapy by depletion of gonadal testosterone. The response is usually transient, and metastatic tumors almost invariably eventually progress as castration-resistant prostate cancer (CRPC). The development of CRPC is dependent upon the intratumoral generation of the potent androgen, dihydrotestosterone (DHT), from adrenal precursor steroids. Progression to CRPC is accompanied by increased expression of steroid-5α-reductase isoenzyme-1 (SRD5A1) over SRD5A2, which is otherwise the dominant isoenzyme expressed in the prostate. DHT synthesis in CRPC is widely assumed to require 5α-reduction of testosterone as the obligate precursor, and the increased expression of SRD5A1 is thought to reflect its role in converting testosterone to DHT. Here, we show that the dominant route of DHT synthesis in CRPC bypasses testosterone, and instead requires 5α-reduction of androstenedione by SRD5A1 to 5α-androstanedione, which is then converted to DHT. This alternative pathway is operational and dominant in both human CRPC cell lines and fresh tissue obtained from human tumor metastases. Moreover, CRPC growth in mouse xenograft models is dependent upon this pathway, as well as expression of SRD5A1. These findings reframe the fundamental metabolic pathway that drives CRPC progression, and shed light on the development of new therapeutic strategies.

Steroid 5α-reductase 3 (SRD5A3) is an important molecule involved in glycosylation and steroid hormone formation and is highly expressed in most tumors. However, The role of SRD5A3 in B-cell non-Hodgkin lymphoma (B-NHL) and its mechanism are unknown. We used a multi-omics database to explore the expression and prognostic significance of SRD5A3 in various tumors, including B-NHL. We established SRD5A3 high- and low-expression B-NHL cell lines to test the effects of SRD5A3 on cell proliferation and apoptosis in vitro, and to analyze the signaling pathways associated with the effects of SRD5A3 on B-NHL. We found that SRD5A3 was highly expressed in most tumors, including B-NHL, and was more highly expressed in patients age ≥60 years, high levels of LDH, stage III-IV, non-GCB subtype, and extra-nodal invasion. Survival analysis showed that high SRD5A3 expression predicted poorer overall survival (OS). Further experiments showed that SRD5A3 high expression promoted B-NHL growth and attenuates apoptosis, conversely, SRD5A3 low expression inhibited B-NHL growth and promoted apoptosis. Western blot assay showed SRD5A3 promotes B-NHL cells growth by regulating the PI3K-AKT signaling pathway. Our findings suggest that SRD5A3 exerts its oncogenic effects by regulating the PI3K-AKT pathway, may serve as a potential biomarker and therapeutic target for B-NHL, providing information for clinical decision-making.