Human 3beta-hydroxysteroid dehydrogenase types 1 and 2: Gene sequence variation and functional genomics

Transcriptional Reprogramming of Candida tropicalis in Response to Isoespintanol Treatment

Candida tropicalis, an opportunistic pathogen, ranks among the primary culprits of invasive candidiasis, a condition notorious for its resistance to conventional antifungal drugs. The urgency to combat these drug-resistant infections has spurred the quest for novel therapeutic compounds, with a particular focus on those of natural origin. In this study, we set out to evaluate the impact of isoespintanol (ISO), a monoterpene derived from Oxandra xylopioides, on the transcriptome of C. tropicalis. Leveraging transcriptomics, our research aimed to unravel the intricate transcriptional changes induced by ISO within this pathogen. Our differential gene expression analysis unveiled 186 differentially expressed genes (DEGs) in response to ISO, with a striking 85% of these genes experiencing upregulation. These findings shed light on the multifaceted nature of ISO's influence on C. tropicalis, spanning a spectrum of physiological, structural, and metabolic adaptations. The upregulated DEGs predominantly pertained to crucial processes, including ergosterol biosynthesis, protein folding, response to DNA damage, cell wall integrity, mitochondrial activity modulation, and cellular responses to organic compounds. Simultaneously, 27 genes were observed to be repressed, affecting functions such as cytoplasmic translation, DNA damage checkpoints, membrane proteins, and metabolic pathways like trans-methylation, trans-sulfuration, and trans-propylamine. These results underscore the complexity of ISO's antifungal mechanism, suggesting that it targets multiple vital pathways within C. tropicalis. Such complexity potentially reduces the likelihood of the pathogen developing rapid resistance to ISO, making it an attractive candidate for further exploration as a therapeutic agent. In conclusion, our study provides a comprehensive overview of the transcriptional responses of C. tropicalis to ISO exposure. The identified molecular targets and pathways offer promising avenues for future research and the development of innovative antifungal therapies to combat infections caused by this pathogenic yeast.

Identification of a novel candidate HSD3B2 gene variant for familial hypospadias by whole-exome sequencing

Introduction: Hypospadias [MIM: 300633] is one of the most frequent congenital malformations of male external genitalia. The spectrum of genetic variants causing hypospadias is varied, with studies commonly implicating genes critical in the fetal steroidogenic pathway. This is the first genetic study on hypospadias from the Yemen ethnicity and the second to report HSD3B2 mutations in more than one affected individual from the same family. Material and methods: Surgical hypospadias repair was performed on two hypospadias-affected siblings from a consanguineous family. Whole-exome sequencing (WES) was performed to identify the potential pathogenic variant for hypospadias, which was later confirmed by Sanger sequencing. The identified variant was further analyzed for its pathogenicity by using in silico tools such as SIFT, PolyPhen-2, MutationAssessor, MutationTaster, FATHMM, and ConSurf. Results: We identified a novel missense mutation (Chr1:119964631T>A, c.507T>A, p. N169K) in 3β-hydroxysteroid 2-dehydrogenase (HSD3B2) gene by WES. Sanger sequencing confirmed that the variant segregated the disease in the family between the affected and non-affected individuals. Both patients are homozygous, while parents and two unaffected siblings are heterozygous carriers, indicating an autosomal recessive pattern of inheritance. The in silico analysis by all six in silico tools (SIFT, PolyPhen-2, MutationAssessor, MutationTaster, FATHMM, and ConSurf) predicted the variant to be pathogenic/deleterious. Discussion: An abnormal fetal steroidogenic pathway due to genetic influences may affect the development of the male genital tract, including the urethral tract closure and morphogenesis of male genitalia. Furthermore, the pathogenicity of the observed variant in this study, confirmed by multiple in silico tools, characterizes the influence HSD3B2 gene variants may have in the etiology of hypospadias. Conclusion: Understanding of pathogenic manifestation and inheritance of confounding genetic variants in hypospadias is a matter of great concern, especially in familial cases.

Genetic Testing for a Patient with Suspected 3 Beta-Hydroxysteroid Dehydrogenase Deficiency: A Case of Unreported Genetic Variants

3beta-hydroxysteroid dehydrogenase type II deficiency (HSD3B2 deficiency), a rare form of congenital adrenal hyperplasia (CAH), is characterized by varying degrees of salt loss and incomplete masculinization in males and mild virilization or normal external genitalia in females. We report the case of a patient (46XY) showing salt loss and incomplete masculinization, markedly elevated levels of 17OHP (17 hydroxyprogesterone), ACTH (Adreno Cortico Tropic Hormone), testosterone and delta4androstenedione (delta4A), low levels of cortisol and absence of bone skeletal alterations that frequently characterize POR (Cytochrome P450 oxidoreductase) deficiency. Mutation analysis by Sanger sequencing of the HSD3B2 gene showed that the patient presented with a compound heterozygote for two novel variants c.370A>G p.Ser124Gly and c.308-6 G>A. The two HSD3B2 gene variants were also present in the patient’s older brother showing only incomplete masculinization. The in silico analysis revealed a probable damaging effect of c.370A>G p.Ser124Gly: residue p.Ser124 is highly conserved among species and seems to be located in the catalytic site of the enzyme, playing a pivotal role in NAD(H) binding to its substrate. Intronic c.308-6G>A variant is predicted to be likely pathogenic; the substitution seems to cause a change in the splice acceptor site located 6bp downstream of the variant. The two siblings seem to be affected by 3β-HSD2 deficiency; nevertheless, the two novel variants are likely to cause variable expressivity of the disease.

Improvac induces immunocastration by affecting testosterone levels and disrupting spermatogenesis in male broiler chickens

Immunocastration (vaccination against Gonadotropin-releasing hormone (GnRH)) has been regarded as a friendly substitution to physical castration in animals. To date, a few studies have reported the use of Improvac for immunocastration in boar and one study in broiler chickens; however, there is an apparent dearth of scientific evidence regarding the application of Improvac for immunocastration in birds. In the present study, we evaluated the effects of Improvac-based immunocastration on testosterone levels and spermatogenesis in broiler chickens and the effects of Improvac on the expression of genes related to testosterone biosynthesis and metabolism as well as spermatogenesis. The birds were randomly divided into 4 groups (n = 30 each): Control group (non-immunized), Early group (immunized with Improvac at week 3), Late group (immunized with Improvac at week 6), and Early + Late group (immunized with Improvac at weeks 3 and 6). Immunization with Improvac significantly improved the average daily gain compared to the Control group. Of note, following Improvac vaccination, the reproductive efficiency was significantly decreased in male broiler chickens. Furthermore, parameters such as the serum testosterone concentration, spermatogenesis, and the expression levels of genes related to testosterone metabolism (Cyp17A1, Cyp19, HSD3B1, and HSD17B3) and spermatogenesis (Cyclin A1 and Cyclin A2) were significantly reduced in the immunized groups compared to the Control group. Taken together, these findings reveal that immunization against GnRH can be achieved, at least partially, in male broiler chickens. The results of our study also support the hypothesis of using Improvac as an alternative solution to caponization, with considerably improved animal welfare.

Up regulation of the steroid hormone synthesis regulator HSD3B2 is linked to early PSA recurrence in prostate cancer

HSD3B2 plays a crucial role in steroid hormone biosynthesis and is thus of particular interest in hormone dependent tumors such as prostate cancer. To clarify the clinical relevance of HSD3B2 expression in prostate cancer, we analyzed HSD3B2 protein expression by immunohistochemistry on our preexisting tissue microarray with 12.247 annotated cancers. Compared with normal tissue cytoplasmic HSD3B2 staining was stronger in prostate cancers. In 9371 interpretable cancers, HSD3B2 expression was found in 95.5% of cancers and was considered weak in 29.9%, moderate in 40.7% and strong in 24.9%. HSD3B2 up regulation was linked to advanced pathological tumor stage (pT), high Gleason grade, elevated preoperative PSA levels (p < 0.0001 each), lymph node metastasis (p = 0.0019), accelerated cell proliferation (p < 0.0001), androgen receptor (AR) expression (p < 0.0001), and early biochemical recurrence (p < 0.0001). HSD3B2 up regulation was only marginally more frequent in ERG positive (98%) than in ERG negative cancers (94%; p < 0.0001) and was strongly linked to deletions of 5q and 6q (p < 0.0001 each). Multivariate analyses showed that the prognostic impact of HSD3B2 expression was independent of established preoperative, but not of postoperative prognostic parameters. In summary, the results of our study demonstrate that HSD3B2 is strongly up regulated in a fraction of prostate cancers that are characterized by increased AR signaling, adverse tumor phenotype and early biochemical recurrence.

Molecular basis for prostate cancer racial disparities

Prostate cancer (PCa) remains the most common cancer in American men. African-American (AA) men continue to have higher PCa prevalence and mortality rates compared to men in other populations. In addition to socioeconomic factors and lifestyle differences, molecular alterations contribute to this discrepancy. We summarize molecular genetics research results interrelated with the biology of PCa racial disparity. Androgen and androgen receptor (AR) pathways have long been associated with prostate growth. Racial differences have also been found among variants of genes of the enzymes involved in androgen biosynthesis and metabolism. Growth factors and their receptors are a potential cause of the disparity in PCa. Recent molecular and biotechnological approaches in the field of proteomics and genomics will greatly aid the advancement of translational research on racial disparity in PCa, which may help, in finding new prognostic markers and novel therapeutic approaches for the treatment of PCa in AA.

Regulation of human (adrenal) androgen biosynthesis-New insights from novel throughput technology studies

Androgens are precursors for sex steroids and are predominantly produced in the human gonads and the adrenal cortex. They are important for intrauterine and postnatal sexual development and human reproduction. Although human androgen biosynthesis has been extensively studied in the past, exact mechanisms underlying the regulation of androgen production in health and disease remain vague. Here, the knowledge on human androgen biosynthesis and regulation is reviewed with a special focus on human adrenal androgen production and the hyperandrogenic disorder of polycystic ovary syndrome (PCOS). Since human androgen regulation is highly specific without a good animal model, most studies are performed on patients harboring inborn errors of androgen biosynthesis, on human biomaterials and human (tumor) cell models. In the past, most studies used a candidate gene approach while newer studies use high throughput technologies to identify novel regulators of androgen biosynthesis. Using genome wide association studies on cohorts of patients, novel PCOS candidate genes have been recently described. Variant 2 of the DENND1A gene was found overexpressed in PCOS theca cells and confirmed to enhance androgen production. Transcriptome profiling of dissected adrenal zones established a role for BMP4 in androgen synthesis. Similarly, transcriptome analysis of human adrenal NCI-H295 cells identified novel regulators of androgen production. Kinase p38α (MAPK14) was found to phosphorylate CYP17 for enhanced 17,20 lyase activity and RARB and ANGPTL1 were detected in novel networks regulating androgens. The discovery of novel players for androgen biosynthesis is of clinical significance as it provides targets for diagnostic and therapeutic use.

Two novel HSD3B2 missense mutations with diverse residual enzymatic activities for Δ5-steroids

CONTEXT

Classical 3β-hydroxysteroid dehydrogenase (3β-HSD) deficiency (3β-HSDD) is caused by loss-of-function mutations in the HSD3B2 gene encoding type II 3β-HSD, which has a key role in steroid biosynthesis, converting Δ5-steroids to Δ4-steroids in adrenal glands and gonads.

PATIENT

A patient (46, XX) was found to have elevated 17-hydroxyprogesterone (17-OHP) [203 nmol/l (normal range: 2·94 ± 0·9 nmol/l)] by newborn screening. Endocrinological examination revealed dramatically increased Δ5-steroids [e.g. 17-OH pregnenolone: 910 nmol/l (normal range: 12·6 ± 10·5 nmol/l)]. The patient had virilization of external genitalia with labial fusion, suggesting classical 3β-HSDD.

METHODS AND RESULTS

Consistent with the endocrinological data, the patient was a compound heterozygote for two novel missense mutations (p.Y190C and p.S218P) that were identified in HSD3B2. Both Y190 and S218 are conserved among mammals. The mutant proteins had severely impaired residual enzymatic activity in vitro, although both mutants retained higher activity for 17-OH pregnenolone than for the other Δ5-steroids. In a three-dimensional model of the enzyme based on the known structures of similar proteins, both mutations were located extremely close to the predicted substrate-binding pocket. This suggests that the mutations can cause a local conformational change in the substrate-binding pocket, leading to alterations of the binding affinities for Δ5-steroids.

CONCLUSIONS

We identified two novel missense mutations of HSD3B2 that resulted in unbalanced residual enzymatic activities for Δ5-steroids. As a potential novel mechanism, we propose that the mutations, which differently affect the activity towards different substrates, the effects of these mutations provide novel insights into the pathophysiology of 3β-HSDD.

Serum androgen bioactivity is low in children with premature adrenarche

BACKGROUND

Clinical findings in children with premature adrenarche (PA) correlate only partly with circulating levels of adrenal androgens. It is not known whether the prepubertal low circulating concentrations of testosterone (T) and dihydrotestosterone, together with those of adrenal androgens, are capable of activating the androgen receptor.

METHODS

This cross-sectional study was performed at a university hospital. Circulating androgen bioactivity was measured in 67 prepubertal children with clinical signs of PA and 94 control children using a novel androgen bioassay.

RESULTS

Circulating androgen bioactivity was low in the PA and control children. In the subgroup of children (n = 28) with serum T concentration over the assay sensitivity (0.35 nmol/l) and a signal in the androgen bioassay, we found a positive correlation between androgen bioactivity and serum T (r = 0.50; P < 0.01) and the free androgen index (r = 0.61; P < 0.01) and a negative correlation with serum sex hormone-binding globulin concentration (r = -0.41; P < 0.05).

CONCLUSION

Peripheral metabolism of adrenal androgen precursors may be required for any androgenic effects in PA. However, the limitations in the sensitivity of the bioassay developed herein may hide some differences between the PA and control children.

Association of the variations in the HSD3β gene with primary aldosteronism

OBJECTIVE

In mice, a lack of cryptochrome results in up-regulation of aldosterone production due to high expression of the 3β-hydroxysteroid dehydrogenases (HSD3β) gene. The HSD3β pathway might play a pivotal role in aldosterone synthesis. This study aimed to determine the association of HSD3β and HSD3β2 gene variations with primary aldosteronism in a Taiwanese population.

METHOD

In this case-control cohort, 688 consecutive ethnically matched unrelated individuals including 362 primary aldosteronism and 326 essential hypertension cases were recruited. Nineteen tag single-nucleotide polymorphisms (SNPs) across HSD3β1, HSD3β2, and CYP11β2 were genotyped. Expression of HSD3β mRNA and immunohistochemical stain of HSD3β in the specimens of aldosterone-producing adenoma (APA) was compared with that in nonfunctional incidentaloma.

RESULTS

The SNPs of rs12410453 A allele in HSD3β2 gene [odds ratio (OR) 1.92, 95% confidence interval (CI) 1.13-3.32, P=0.018] and rs6203 C allele in the HSD3β1 gene (OR 2.21, 95% CI 1.28-3.95, P=0.006) showed significant association with primary aldosteronism, with corresponding population attributable risk of 6.7 and 30.7%, respectively. Primary aldosteronism patients of non-CC in rs6203 and non-GA in rs12401453 had lower plasma aldosterone-to-renin ratio. A haplotype in a linkage disequilibrium block containing rs6203 associated significantly with serum potassium level (OR 1.24, 95% CI 1.02-1.24, P=0.026). The expressions of HSD3β1 mRNA, HSD3β2 mRNA and HSD3β protein were increased in APA, as compared to incidentaloma.

CONCLUSION

Risk-conferring genetic variations in the HSD3β gene influenced susceptibility of primary aldosteronism. Concomitant presence of rs6203 CC and rs12410453 GA genotypes synergistically increased aldosterone-to-renin ratio.

Albuminuria is associated with too few glomeruli and too much testosterone

Normally, the glomerular filtration barrier almost completely excludes circulating albumin from entering the urine. Genetic variation and both pre- and postnatal environmental factors may affect albuminuria in humans. Here we determine whether glomerular gene expression in mouse strains with naturally occurring variations in albuminuria would allow identification of proteins deregulated in relatively 'leaky' glomeruli. Albuminuria increased in female B6 to male B6 to female FVB/N to male FVB/N mice, whereas the number of glomeruli/kidney was the exact opposite. Testosterone administration led to increased albuminuria in female B6 but not female FVB/N mice. A common set of 39 genes, many expressed in podocytes, were significantly differentially expressed in each of the four comparisons: male versus female B6 mice, male versus female FVB/N mice, male FVB/N versus male B6 mice, and female FVB/N versus female B6 mice. The transcripts encoded proteins involved in oxidation/reduction reactions, ion transport, and enzymes involved in detoxification. These proteins may represent novel biomarkers and even therapeutic targets for early kidney and cardiovascular disease.

Ethnical disparities of prostate cancer predisposition: genetic polymorphisms in androgen-related genes

Prostate cancer (PCa) is the most commonly diagnosed male malignancy and the second biggest cause of cancer death in men of the Western world. Higher incidences of PCa occur in men from North America, Oceania and Western countries, whereas men from Asia and North Africa have a much lower PCa incidence rate. Investigations into this population disparity of PCa incidence, in order to identify potential preventive factors or targets for the therapeutic intervention of PCa, have found differences in both environmental and genetic variations between these populations. Environmental variations include both diet and lifestyle, which vary widely between populations. Evidence that diet comes into play has been shown by men who immigrate from Eastern to Western countries. PCa incidence in these men is higher than men in their native countries. However the number of immigrants developing PCa still doesn't match native black/white men, therefore genetic factors also contribute to PCa risk, which are supported by familial studies. There are a number of genetic polymorphisms that are differentially presented between Western and Eastern men, which are potentially associated with PCa incidence. Androgen and its receptor (AR) play a major role in PCa development and progression. In this study, we focus on genes involved in androgen biosynthesis and metabolism, as well as those associated with AR pathway, whose polymorphisms affect androgen level and biological or physiological functions of androgen. While many of the genetic polymorphisms in this androgen/AR system showed different frequencies between populations, contradictory evidences exist for most of these genes investigated individually as to the true contribution to PCa risk. More accurate measurements of androgen activity within the prostate are required and further studies need to include more African and Asian subjects. As many of these genetic polymorphisms may contribute to different steps in the same biological/physiological function of androgen and AR pathway, an integrated analysis considering the combined effect of all the genetic polymorphisms may be necessary to assess their contribution to PCa initiation and progression.

HSD3B and gene-gene interactions in a pathway-based analysis of genetic susceptibility to bladder cancer

Bladder cancer is the 4(th) most common cancer among men in the U.S. We analyzed variant genotypes hypothesized to modify major biological processes involved in bladder carcinogenesis, including hormone regulation, apoptosis, DNA repair, immune surveillance, metabolism, proliferation, and telomere maintenance. Logistic regression was used to assess the relationship between genetic variation affecting these processes and susceptibility in 563 genotyped urothelial cell carcinoma cases and 863 controls enrolled in a case-control study of incident bladder cancer conducted in New Hampshire, U.S. We evaluated gene-gene interactions using Multifactor Dimensionality Reduction (MDR) and Statistical Epistasis Network analysis. The 3'UTR flanking variant form of the hormone regulation gene HSD3B2 was associated with increased bladder cancer risk in the New Hampshire population (adjusted OR 1.85 95%CI 1.31-2.62). This finding was successfully replicated in the Texas Bladder Cancer Study with 957 controls, 497 cases (adjusted OR 3.66 95%CI 1.06-12.63). The effect of this prevalent SNP was stronger among males (OR 2.13 95%CI 1.40-3.25) than females (OR 1.56 95%CI 0.83-2.95), (SNP-gender interaction P = 0.048). We also identified a SNP-SNP interaction between T-cell activation related genes GATA3 and CD81 (interaction P = 0.0003). The fact that bladder cancer incidence is 3-4 times higher in males suggests the involvement of hormone levels. This biologic process-based analysis suggests candidate susceptibility markers and supports the theory that disrupted hormone regulation plays a role in bladder carcinogenesis.

Prediction of susceptibility to major depression by a model of interactions of multiple functional genetic variants and environmental factors

Major depressive disorder (MDD) is the most common psychiatric disorder and the second overall cause of disability. Even though a significant amount of the variance in the MDD phenotype is explained by inheritance, specific genetic variants conferring susceptibility to MDD explain only a minimal proportion of MDD causality. Moreover, genome-wide association studies have only identified two small-sized effect loci that reach genome-wide significance. In this study, a group of Mexican-American patients with MDD and controls recruited for a pharmacogenetic study were genotyped for nonsynonymous single-nucleotide polymorphisms (nsSNPs) and used to explore the interactions of multiple functional genetic variants with risk-classification tree analysis. The risk-classification tree analysis model and linkage disequilibrium blocks were used to replicate exploratory findings in the database of genotypes and phenotypes (dbGaP) for major depression, and pathway analysis was performed to explore potential biological mechanisms using the branching events. In exploratory analyses, we found that risk-classification tree analysis, using 15 nsSNPs that had a nominal association with MDD diagnosis, identified multiple increased-MDD genotype clusters and significant additive interactions in combinations of genotype variants that were significantly associated with MDD. The results in the dbGaP for major depression disclosed a multidimensional dependent phenotype constituted of MDD plus significant modifiers (smoking, marriage status, age, alcohol abuse/dependence and gender), which then was used for the association tree analysis. The reconstructed tree analysis for the dbGaP data showed robust reliability and replicated most of the genes involved in the branching process found in our exploratory analyses. Pathway analysis using all six major events of branching (PSMD9, HSD3B1, BDNF, GHRHR, PDE6C and PDLIM5) was significant for positive regulation of cellular and biological processes that are relevant to growth and organ development. Our findings not only provide important insights into the biological pathways underlying innate susceptibility to MDD but also offer a predictive framework based on interactions of multiple functional genetic variants and environmental factors. These findings identify novel targets for therapeutics and for translation into preventive, clinical and personalized health care.

The proteome of cytosolic lipid droplets isolated from differentiated Caco-2/TC7 enterocytes reveals cell-specific characteristics

Background information. Intestinal absorption of alimentary lipids is a complex process ensured by enterocytes and leading to TRL [TAG (triacylglycerol)-rich lipoprotein] assembly and secretion. The accumulation of circulating intestine-derived TRL is associated with atherosclerosis, stressing the importance of the control of postprandial hypertriglyceridaemia. During the postprandial period, TAGs are also transiently stored as CLDs (cytosolic lipid droplets) in enterocytes. As a first step for determining whether CLDs could play a role in the control of enterocyte TRL secretion, we analysed the protein endowment of CLDs isolated by sucrose-gradient centrifugation from differentiated Caco-2/TC7 enterocytes, the only human model able to secrete TRL in culture and to store transiently TAGs as CLDs when supplied with lipids. Cells were analysed after a 24 h incubation with lipid micelles and thus in a state of CLD-associated TAG mobilization.

Results. Among the 105 proteins identified in the CLD fraction by LC-MS/MS (liquid chromatography coupled with tandem MS), 27 were directly involved in lipid metabolism pathways potentially relevant to enterocyte-specific functions. The transient feature of CLDs was consistent with the presence of proteins necessary for fatty acid activation (acyl-CoA synthetases) and for TAG hydrolysis. In differentiated Caco-2/TC7 enterocytes, we identified for the first time LPCAT2 (lysophosphatidylcholine acyltransferase 2), involved in PC (phosphatidylcholine) synthesis, and 3BHS1 (3-β-hydroxysteroid dehydrogenase 1), involved in steroid metabolism, and confirmed their partial CLD localization by immunofluorescence. In enterocytes, LPCAT2 may provide an economical source of PC, necessary for membrane synthesis and lipoprotein assembly, from the lysoPC present in the intestinal lumen. We also identified proteins involved in lipoprotein metabolism, such as ApoA-IV (apolipoprotein A-IV), which is specifically expressed by enterocytes and has been proposed to play many functions in vivo, including the formation of lipoproteins and the control of their size. The association of ApoA-IV with CLD was confirmed by confocal and immunoelectron microscopy and validated in vivo in the jejunum of mice fed with a high-fat diet.

Conclusions. We report for the first time the protein endowment of Caco-2/TC7 enterocyte CLDs. Our results suggest that their formation and mobilization may participate in the control of enterocyte TRL secretion in a cell-specific manner.

Gene expression in hypothalamus, liver, and adipose tissues and food intake response to melanocortin-4 receptor agonist in pigs expressing melanocortin-4 receptor mutations

Transcriptional profiling was used to identify genes and pathways that responded to intracerebroventricular injection of melanocortin-4 receptor (MC4R) agonist [Nle4, d-Phe7]-α-melanocyte stimulating hormone (NDP-MSH) in pigs homozygous for the missense mutation in the MC4R, D298 allele ( n = 12), N298 allele ( n = 12), or heterozygous ( n = 12). Food intake (FI) was measured at 12 and 24 h after treatment. All pigs were killed at 24 h after treatment, and hypothalamus, liver, and back-fat tissue was collected. NDP-MSH suppressed ( P < 0.004) FI at 12 and 24 h in all animals after treatment. In response to NDP-MSH, 278 genes in hypothalamus ( q ≤ 0.07, P ≤ 0.001), 249 genes in liver ( q ≤ 0.07, P ≤ 0.001), and 5,066 genes in fat ( q ≤ 0.07, P ≤ 0.015) were differentially expressed. Pathway analysis of NDP-MSH-induced differentially expressed genes indicated that genes involved in cell communication, nucleotide metabolism, and signal transduction were prominently downregulated in the hypothalamus. In both liver and adipose tissue, energy-intensive biosynthetic and catabolic processes were downregulated in response to NDP-MSH. This included genes encoding for biosynthetic pathways such as steroid and lipid biosynthesis, fatty acid synthesis, and amino acid synthesis. Genes involved in direct energy-generating processes, such as oxidative phosphorylation, electron transport, and ATP synthesis, were upregulated, whereas TCA-associated genes were prominently downregulated in NDP-MSH-treated pigs. Our data also indicate a metabolic switch toward energy conservation since genes involved in energy-intensive biosynthetic and catabolic processes were downregulated in NDP-MSH-treated pigs.

Proteasome beta subunit pharmacogenomics: gene resequencing and functional genomics

PURPOSE

The proteasome is a multisubunit cellular organelle that functions as a nonlysosomal threonine protease. Proteasomes play a critical role in the degradation of proteins, regulating a variety of cellular processes, and they are also the target for antineoplastic proteasome inhibitors. Genetic variation in proteasome subunits could influence both proteasome function and response to drug therapy.

EXPERIMENTAL DESIGN

We resequenced genes encoding the three active proteasome beta subunits using 240 DNA samples from four ethnic groups and the beta 5 subunit gene in 79 DNA samples from multiple myeloma patients who had been treated with the proteasome inhibitor bortezomib. Resequencing was followed by functional studies of polymorphisms identified in the coding region and 3'-flanking region (3'-FR) of PSMB5, the gene encoding the target for clinically useful proteasome inhibitors.

RESULTS

Resequencing of 240 DNA samples identified a series of novel ethnic-specific polymorphisms that are not represented in public databases. The PSMB5 3'-FR 1042 G allele significantly increased transcription during reporter gene studies, observations confirmed by genotype-phenotype correlations between single nucleotide polymorphisms (SNP) in PSMB5 and mRNA expression in the 240 lymphoblastoid cell lines from which the resequenced DNA was obtained. Studies with patient DNA samples identified additional novel PSMB5 polymorphisms, including a SNP and an insertion in the 3'-FR. Reporter-gene studies indicated that these two novel polymorphisms might decrease transcription.

CONCLUSIONS

These results show that nonsynonymous coding SNPs in the PSMB5 gene did not show significant effects on proteasome activity, but SNPs did influence transcription. Future studies might focus on regulatory region polymorphisms.