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HSD17B4 - Top 30 Publications

PDGFRA, HSD17B4 and HMGB2 are potential therapeutic targets in polycystic ovarian syndrome and breast cancer.

To explore the key genes associated with both PCOS and breast cancer, we overlapped the synchronously differently expressed genes in two obese insulin-resistant GEO datasets in muscle tissue and genes exert essential roles in breast cancer prognosis together base on the following reasons: (1) Androgens excess is believed to contribute to the onset of both PCOS and breast cancer. (2) PCOS is usually complicated with metabolic symptoms, such as obesity and insulin-resistance. (3) Muscle is the main place where energy metabolism and material metabolism take place. Consequently, 53 genes were found, functionally enriched in pathways such as pyruvate metabolism, muscle system process and development of primary male sexual characteristics etc. We further lay our eyes on genes correlated with male sexual characteristics, which may be involved in the onset of both PCOS and breast cancer. Three genes were indicated to be associated with this process, including hydroxysteroid (17-beta) dehydrogenase 4/HSD17B4, platelet-derived growth factor receptor, alpha polypeptide/PDGFRA and high-mobility group box 2/HMGB2. Gene-drug interaction network about the three genes were then constructed. Drugs or chemicals that contribute to correcting the disorder of lipid metabolism were detected to restore the abnormal expression of the three genes in PCOS, such as simvastatin, bezafibrate, fenofibrate et al, which provide further choices for managing patients with PCOS.

Developing antineoplastic agents that target peroxisomal enzymes: cytisine-linked isoflavonoids as inhibitors of hydroxysteroid 17-beta-dehydrogenase-4 (HSD17B4).

Cytisine-linked isoflavonoids (CLIFs) inhibited PC-3 prostate and LS174T colon cancer cell proliferation by inhibiting a peroxisomal bifunctional enzyme. A pull-down assay using a biologically active, biotin-modified CLIF identified the target of these agents as the bifunctional peroxisomal enzyme, hydroxysteroid 17β-dehydrogenase-4 (HSD17B4). Additional studies with truncated versions of HSD17B4 established that CLIFs specifically bind the C-terminus of HSD17B4 and selectively inhibited the enoyl CoA hydratase but not the d-3-hydroxyacyl CoA dehydrogenase activity. HSD17B4 was overexpressed in prostate and colon cancer tissues, knocking down HSD17B4 inhibited cancer cell proliferation, suggesting that HSD17B4 is a potential biomarker and drug target and that CLIFs are potential probes or therapeutic agents for these cancers.

A homozygous missense variant in HSD17B4 identified in a consanguineous Chinese Han family with type II Perrault syndrome.

Perrault syndrome is a rare multisystem disorder that manifests with sensorineural hearing loss in both sexes, primary ovarian insufficiency in females and neurological features. The syndrome is heterogeneous both genetically and phenotypically.

Synthesis and Detection by HPLC of 3-Oxohexadecanoyl-CoA for the Study of Peroxisomal Bifunctional Proteins.

3-oxohexadecanoyl-CoA was synthesized for the study of D-bifunctional protein (EC 4. 2. 1. 107, EC 4. 2. 1. 119, EC 1. 1. 1. n12) and L-bifunctional protein (EC 4. 2. 1. 17, EC 5. 3. 3. 8, EC 1. 1. 1. 35). First, tetradecanal was subjected to the Reformatsky reaction with ethyl bromoacetate, and the product was then converted into ethyl 3-oxohexadecanoate. After acetalization of the 3-oxo ester with ethylene glycol, 3,3-ethlenedioxyhexadecanoic acid was obtained by alkaline hydrolysis. The acid was condensed with coenzyme A (CoA) by the mixed anhydride method, and the resulting CoA ester was deprotected with 4 M HCl to obtain 3-oxohexadecanoyl-CoA. In addition, the behavior of the CoA ester under several conditions of high-performance liquid chromatography (HPLC) was also investigated. We established separation detection of (R)-3-hydroxyhexadecanoyl-CoA, (S)-3-hydroxyhexadecaboyl-CoA, 3-oxohexadecanoyl-CoA, and trans-2-hexadecenoyl-CoA.

Clinical and Laboratory Diagnosis of Peroxisomal Disorders.

The peroxisomal disorders (PDs) are a heterogeneous group of genetic diseases in man caused by an impairment in peroxisome biogenesis or one of the metabolic functions of peroxisomes. Thanks to the revolutionary technical developments in gene sequencing methods and their increased use in patient diagnosis, the field of genetic diseases in general and peroxisomal disorders in particular has dramatically changed in the last few years. Indeed, several novel peroxisomal disorders have been identified recently and in addition it has been realized that the phenotypic spectrum of patients affected by a PD keeps widening, which makes clinical recognition of peroxisomal patients increasingly difficult. Here, we describe these new developments and provide guidelines for the clinical and laboratory diagnosis of peroxisomal patients.

Acetylation targets HSD17B4 for degradation via the CMA pathway in response to estrone.

Dysregulation of hormone metabolism is implicated in human breast cancer. 17β-hydroxysteroid dehydrogenase type 4 (HSD17B4) catalyzes the conversion of estradiol (E2) to estrone (E1), and is associated with the pathogenesis and development of various cancers. Here we show that E1 upregulates HSD17B4 acetylation at lysine 669 (K669) and thereby promotes HSD17B4 degradation via chaperone-mediated autophagy (CMA), while a single mutation at K669 reverses the degradation and confers migratory and invasive properties to MCF7 cells upon E1 treatment. CREBBP and SIRT3 dynamically control K669 acetylation level of HSD17B4 in response to E1. More importantly, K669 acetylation is inversely correlated with HSD17B4 in human breast cancer tissues. Our study reveals a crosstalk between acetylation and CMA degradation in HSD17B4 regulation, and a critical role of the regulation in the malignant progression of breast cancer.

Specific suppression of microgliosis cannot circumvent the severe neuropathology in peroxisomal β-oxidation-deficient mice.

An important hallmark of various neurodegenerative disorders is the proliferation and activation of microglial cells, the resident immune cells of the central nervous system (CNS). Mice that lack multifunctional protein-2 (MFP2), the key enzyme in peroxisomal β-oxidation, develop excessive microgliosis that positively correlates with behavioral deficits whereas no neuronal loss occurs. However, the precise contribution of neuroinflammation to the fatal neuropathology of MFP2 deficiency remains largely unknown. Here, we first attempted to suppress the inflammatory response by administering various anti-inflammatory drugs but they failed to reduce microgliosis. Subsequently, Mfp2(-/-) mice were treated with the selective colony-stimulating factor 1 receptor (CSF1R) inhibitor PLX5622 as microglial proliferation and survival is dependent on CSF1R signaling. This resulted in the elimination of >95% of microglia from control mice but only 70% of the expanded microglial population from Mfp2(-/-) mice. Despite microglial diminution in Mfp2(-/-) brain, inflammatory markers remained unaltered and residual microglia persisted in a reactive state. CSF1R inhibition did not prevent neuronal dysfunction, cognitive decline and clinical deterioration of Mfp2(-/-) mice. Collectively, the unaltered inflammatory profile despite suppressed microgliosis concurrent with persevering clinical decline strengthens our hypothesis that neuroinflammation importantly contributes to the Mfp2(-/-) phenotype.

Laser-capture micro dissection combined with next-generation sequencing analysis of cell type-specific deafness gene expression in the mouse cochlea.

Cochlear implantation (CI), which directly stimulates the cochlear nerves, is the most effective and widely used medical intervention for patients with severe to profound sensorineural hearing loss. The etiology of the hearing loss is speculated to have a major influence of CI outcomes, particularly in cases resulting from mutations in genes preferentially expressed in the spiral ganglion region. To elucidate precise gene expression levels in each part of the cochlea, we performed laser-capture micro dissection in combination with next-generation sequencing analysis and determined the expression levels of all known deafness-associated genes in the organ of Corti, spiral ganglion, lateral wall, and spiral limbs. The results were generally consistent with previous reports based on immunocytochemistry or in situ hybridization. As a notable result, the genes associated with many kinds of syndromic hearing loss (such as Clpp, Hars2, Hsd17b4, Lars2 for Perrault syndrome, Polr1c and Polr1d for Treacher Collins syndrome, Ndp for Norrie Disease, Kal for Kallmann syndrome, Edn3 and Snai2 for Waardenburg Syndrome, Col4a3 for Alport syndrome, Sema3e for CHARGE syndrome, Col9a1 for Sticker syndrome, Cdh23, Cib2, Clrn1, Pcdh15, Ush1c, Ush2a, Whrn for Usher syndrome and Wfs1 for Wolfram syndrome) showed higher levels of expression in the spiral ganglion than in other parts of the cochlea. This dataset will provide a base for more detailed analysis in order to clarify gene functions in the cochlea as well as predict CI outcomes based on gene expression data.

Pathological complete response of HER2-positive breast cancer to trastuzumab and chemotherapy can be predicted by HSD17B4 methylation.

Human epidermal growth factor (HER) 2-directed therapy is the standard treatment for HER2-positive breast cancer. Patients who achieved a pathological complete response (pCR) to the therapy are associated with excellent disease-free survival. However, few molecular markers are available to predict pCR. Here, we aimed to establish a DNA methylation marker to predict the response to trastuzumab and chemotherapy. A total of 67 patients were divided into screening (n = 21) and validation (n = 46) sets. Genome-wide DNA methylation analysis of the screening set identified eight genomic regions specifically methylated in patients with pCR. Among these, HSD17B4 encoding type 4 17β-hydroxysteroid dehydrogenase was most significantly differentially methylated. The differential methylation was confirmed by pyrosequencing (P = 0.03), and a cutoff value was determined. This association was successfully validated in the validation set (P < 0.001), and patients with pCR were predicted with a high specificity (79%). Multivariate analysis, including tumor stage and hormone receptor status, showed that HSD17B4 methylation was an independent predictive factor (odds ratio: 10.0, 95% confidence interval 2.54-39.50, P = 0.001). Combination with ER status and HSD17B4 methylation improved the specificity up to 91%. Identification of HER2-positive breast cancer patients who would achieve pCR only by trastuzumab and chemotherapy may lead to surgery-free treatment for this group of breast cancer patients.

A New Immunomodulatory Role for Peroxisomes in Macrophages Activated by the TLR4 Ligand Lipopolysaccharide.

Peroxisomes are proposed to play an important role in the regulation of systemic inflammation; however, the functional role of these organelles in inflammatory responses of myeloid immune cells is largely unknown. In this article, we demonstrate that the nonclassical peroxisome proliferator 4-phenyl butyric acid is an efficient inducer of peroxisomes in various models of murine macrophages, such as primary alveolar and peritoneal macrophages and the macrophage cell line RAW264.7, but not in primary bone marrow-derived macrophages. Further, proliferation of peroxisomes blocked the TLR4 ligand LPS-induced proinflammatory response, as detected by the reduced induction of the proinflammatory protein cyclooxygenase (COX)-2 and the proinflammatory cytokines TNF-α, IL-6, and IL-12. In contrast, disturbing peroxisome function by knockdown of peroxisomal gene Pex14 or Mfp2 markedly increased the LPS-dependent upregulation of the proinflammatory proteins COX-2 and TNF-α. Specifically, induction of peroxisomes did not affect the upregulation of COX-2 at the mRNA level, but it reduced the half-life of COX-2 protein, which was restored by COX-2 enzyme inhibitors but not by proteasomal and lysosomal inhibitors. Liquid chromatography-tandem mass spectrometry analysis revealed that various anti-inflammatory lipid mediators (e.g., docosahexaenoic acid) were increased in the conditioned medium from peroxisome-induced macrophages, which blocked LPS-induced COX-2 upregulation in naive RAW264.7 cells and human primary peripheral blood-derived macrophages. Importantly, LPS itself induced peroxisomes that correlated with the regulation of COX-2 during the late phase of LPS activation in macrophages. In conclusion, our findings identify a previously unidentified role for peroxisomes in macrophage inflammatory responses and suggest that peroxisomes are involved in the physiological cessation of macrophage activation.

Novel neuro-audiological findings and further evidence for TWNK involvement in Perrault syndrome.

Hearing loss and ovarian dysfunction are key features of Perrault syndrome (PRLTS) but the clinical and pathophysiological features of hearing impairment in PRLTS individuals have not been addressed. Mutations in one of five different genes HSD17B4, HARS2, LARS2, CLPP or TWNK (previous symbol C10orf2) cause the autosomal recessive disorder but they are found only in about half of the patients.

Comparative Analysis of Mitochondrial N-Termini from Mouse, Human, and Yeast.

The majority of mitochondrial proteins are encoded in the nuclear genome, translated in the cytoplasm, and directed to the mitochondria by an N-terminal presequence that is cleaved upon import. Recently, N-proteome catalogs have been generated for mitochondria from yeast and from human U937 cells. Here, we applied the subtiligase method to determine N-termini for 327 proteins in mitochondria isolated from mouse liver and kidney. Comparative analysis between mitochondrial N-termini from mouse, human, and yeast proteins shows that whereas presequences are poorly conserved at the sequence level, other presequence properties are extremely conserved, including a length of ∼20-60 amino acids, a net charge between +3 to +6, and the presence of stabilizing amino acids at the N-terminus of mature proteins that follow the N-end rule from bacteria. As in yeast, ∼80% of mouse presequence cleavage sites match canonical motifs for three mitochondrial peptidases (MPP, Icp55, and Oct1), whereas the remainder do not match any known peptidase motifs. We show that mature mitochondrial proteins often exist with a spectrum of N-termini, consistent with a model of multiple cleavage events by MPP and Icp55. In addition to analysis of canonical targeting presequences, our N-terminal dataset allows the exploration of other cleavage events and provides support for polypeptide cleavage into two distinct enzymes (Hsd17b4), protein cleavages key for signaling (Oma1, Opa1, Htra2, Mavs, and Bcs2l13), and in several cases suggests novel protein isoforms (Scp2, Acadm, Adck3, Hsdl2, Dlst, and Ogdh). We present an integrated catalog of mammalian mitochondrial N-termini that can be used as a community resource to investigate individual proteins, to elucidate mechanisms of mammalian mitochondrial processing, and to allow researchers to engineer tags distally to the presequence cleavage.

Slowly progressive d-bifunctional protein deficiency with survival to adulthood diagnosed by whole-exome sequencing.

d-Bifunctional protein (DBP) deficiency is an autosomal recessive disorder of peroxisomal fatty acid oxidation caused by mutations in HSD17B4. It is typically fatal by the age of two years with symptom onset during the neonatal period, and survival until late childhood is rare. We herein report the case of a patient with DBP deficiency surviving until adulthood, who showed severe sensorineural deafness, disturbances in language acquisition, slowly progressive cerebellar ataxia, and peripheral neuropathy. This patient, in whom findings of prior investigations were nondiagnostic, had been followed up as having an early-onset spinocerebellar degeneration of unknown etiology. Whole-exome sequencing analysis at the age of 36 showed two heterozygous variants in the gene HSD17B4, which encodes DBP in this patient. A panel of peroxisomal investigations showed normal levels of very long chain fatty acids (VLCFAs) in plasma and elevated serum phytanic acid levels. Recently, an increasing number of patients with DBP deficiency surviving until adolescence/adulthood have been reported, in whom abnormalities in the levels of VLCFAs and other peroxisomal metabolites are marginal or nonexistent. Genetic analysis of HSD17B4 should be considered in adult patients with cerebellar ataxia, peripheral neuropathy, and pyramidal signs in addition to sensorineural auditory disturbance since childhood.

Association between a non-synonymous HSD17B4 single nucleotide polymorphism and meat-quality traits in Berkshire pigs.

Single nucleotide polymorphisms (SNPs) are useful genetic markers that allow correlation of genetic sequences with phenotypic traits. It is shown here that HSD17B4, a bifunctional enzyme mediating dehydrogenation and anhydration during β-oxidation of long-chain fatty acids, contains a non-synonymous SNP (nsSNP) of chr2:128,825,976A>G, c.2137A>G, I690V, within the sterol carrier protein-2 domain of the HSD17B4 gene, by RNA-Seq of liver RNA. The HSD17B4 mRNA was highly expressed in the kidney and liver among various other tissues in four pig breeds, namely, Berkshire, Duroc, Landrace, and Yorkshire. The nsSNP was significantly associated with carcass weight, backfat thickness, and drip loss (P < 0.05). Furthermore, HSD17B4 may play a crucial role during the early stages of myogenesis when expression of its mRNA was significantly high. In conclusion, HSD17B4 may serve as a possible regulator of muscle development, and its identification should help to select for improved economic traits of Berkshire pigs such as carcass weight, backfat thickness, and drip loss.

Heterozygous mutations in HSD17B4 cause juvenile peroxisomal D-bifunctional protein deficiency.

To determine the genetic cause of slowly progressive cerebellar ataxia, sensorineural deafness, and hypergonadotropic hypogonadism in 5 patients from 3 different families.

An Application of NGS for Molecular Investigations in Perrault Syndrome: Study of 14 Families and Review of the Literature.

Perrault syndrome (PS) is a rare autosomal recessive condition characterized by deafness and gonadic dysgenesis. Recently, mutations in five genes have been identified: C10orf2, CLPP, HARS2, HSD17B4, and LARS2. Probands included are presented with sensorineural deafness associated with gonadic dysgenesis. DNA was sequenced using next-generation sequencing (NGS) with a panel of 35 deafness genes including the five Perrault genes. Exonic variations known as pathogenic mutations or detected with <1% frequency in public databases were extracted and subjected to segregation analysis within each family. Both mutations and low coverage regions were analyzed by Sanger sequencing. Fourteen female index patients were included. The screening in four cases has been extended to four family members presenting with PS phenotype. For four unrelated patients (28.6%), causative mutations were identified: three homozygous mutations in C10orf2, CLPP, and HARS2, and one compound heterozygous mutation in LARS2. Three additional heterozygous mutations in LARS2 and HSD17B4 were found in three independent familial cases. All these missense mutations were verified by Sanger sequencing. Familial segregation analyses confirmed the molecular diagnosis in all cases carrying biallelic mutations. Because of NGS, molecular analysis confirmed the clinical diagnosis of PS in 28.6% of our cohort and four novel mutations were found in four Perrault genes. For the unsolved cases, exome sequencing should be performed to search for a sixth unknown PS gene.

Mini-Exome Coupled to Read-Depth Based Copy Number Variation Analysis in Patients with Inherited Ataxias.

Next-generation sequencing (NGS) has an established diagnostic value for inherited ataxia. However, the need of a rigorous process of analysis and validation remains challenging. Moreover, copy number variations (CNV) or dynamic expansions of repeated sequence are classically considered not adequately detected by exome sequencing technique. We applied a strategy of mini-exome coupled to read-depth based CNV analysis to a series of 33 patients with probable inherited ataxia and onset <50 years. The mini-exome consisted of the capture of 4,813 genes having associated clinical phenotypes. Pathogenic variants were found in 42% and variants of uncertain significance in 24% of the patients. These results are comparable to those from whole exome sequencing and better than previous targeted NGS studies. CNV and dynamic expansions of repeated CAG sequence were identified in three patients. We identified both atypical presentation of known ataxia genes (ATM, NPC1) and mutations in genes very rarely associated with ataxia (ERCC4, HSD17B4). We show that mini-exome bioinformatics data analysis allows the identification of CNV and dynamic expansions of repeated sequence. Our study confirms the diagnostic value of the proposed genetic analysis strategy. We also provide an algorithm for the multidisciplinary process of analysis, interpretation, and validation of NGS data.

New perspective in diagnostics of mitochondrial disorders: two years' experience with whole-exome sequencing at a national paediatric centre.

Whole-exome sequencing (WES) has led to an exponential increase in identification of causative variants in mitochondrial disorders (MD).

Using In Vitro High-Throughput Screening Data for Predicting BenzokFluoranthene Human Health Hazards.

Today there are more than 80,000 chemicals in commerce and the environment. The potential human health risks are unknown for the vast majority of these chemicals as they lack human health risk assessments, toxicity reference values, and risk screening values. We aim to use computational toxicology and quantitative high-throughput screening (qHTS) technologies to fill these data gaps, and begin to prioritize these chemicals for additional assessment. In this pilot, we demonstrate how we were able to identify that benzo[k]fluoranthene may induce DNA damage and steatosis using qHTS data and two separate adverse outcome pathways (AOPs). We also demonstrate how bootstrap natural spline-based meta-regression can be used to integrate data across multiple assay replicates to generate a concentration-response curve. We used this analysis to calculate an in vitro point of departure of 0.751 μM and risk-specific in vitro concentrations of 0.29 μM and 0.28 μM for 1:1,000 and 1:10,000 risk, respectively, for DNA damage. Based on the available evidence, and considering that only a single HSD17B4 assay is available, we have low overall confidence in the steatosis hazard identification. This case study suggests that coupling qHTS assays with AOPs and ontologies will facilitate hazard identification. Combining this with quantitative evidence integration methods, such as bootstrap meta-regression, may allow risk assessors to identify points of departure and risk-specific internal/in vitro concentrations. These results are sufficient to prioritize the chemicals; however, in the longer term we will need to estimate external doses for risk screening purposes, such as through margin of exposure methods.

A Novel Missense Mutation in the CLPP Gene Causing Perrault Syndrome Type 3 in a Turkish Family.

Perrault syndrome (PRLTS) is a heterogeneous group of clinical and genetic disorders characterized by sensory neuronal hearing loss in both sexes and premature ovarian failure or infertility in females. Neurological and hearing loss symptoms appear early in life, but female infertility cannot be detected before puberty. Spastic limbs, muscle weakness, delayed puberty and irregular menstrual cycles have also been observed in PRLTS patients. Mutations in five genes, i.e. HSD17B4, HARS2, CLPP, LARS2, and C10orf2, have been reported in five subtypes of PRLTS. Here, we report a milder phenotype of PRLTS in a Turkish family in which two affected patients had no neurological findings. However, both were characterized by sensory neuronal hearing loss and the female sibling had secondary amenorrhea and gonadal dysgenesis. Genome-wide homozygosity mapping using 300K single-nucleotide polymorphism microarray analysis together with iScan platform (Illumina, USA) followed by candidate gene Sanger sequencing with ABI 3500 Genetic Analyzer (Life Technologies, USA) were used for molecular diagnosis. We found a novel missense alteration c.624C>G; p.Ile208Met in exon 5 of the CLPP at chromosome 19p13.3. This study expands the mutation spectrum of CLPP pathogenicity in PRLTS type 3 phenotype.

Expanding the genotypic spectrum of Perrault syndrome.

Perrault syndrome is a rare autosomal recessive disorder characterized by sensorineural hearing loss (SNHL) in both sexes and primary ovarian insufficiency in 46, XX karyotype females. Biallelic variants in five genes are reported to be causative: HSD17B4, HARS2, LARS2, CLPP and C10orf2. Here we present eight families affected by Perrault syndrome. In five families we identified novel or previously reported variants in HSD17B4, LARS2, CLPP and C10orf2. The proband from each family was whole exome sequenced and variants confirmed by Sanger sequencing. A female was compound heterozygous for a known, p.(Gly16Ser) and novel, p.(Val82Phe) variant in D-bifunctional protein (HSD17B4). A family was homozygous for mitochondrial leucyl aminocyl tRNA synthetase (mtLeuRS) (LARS2) p.(Thr522Asn), previously associated with Perrault syndrome. A further family was compound heterozygous for mtLeuRS, p.(Thr522Asn) and a novel variant, p.(Met117Ile). Affected individuals with LARS2 variants had low frequency SNHL, a feature previously described in Perrault syndrome. A female with significant neurological disability was compound heterozygous for p.(Arg323Gln) and p.(Asn399Ser) variants in Twinkle (C10orf2). A male was homozygous for a novel variant in CLPP, p.(Cys144Arg). In three families there were no putative pathogenic variants in these genes confirming additional disease-causing genes remain unidentified. We have expanded the spectrum of disease-causing variants associated with Perrault syndrome.

Diagnosis of D-Bifunctional Protein Deficiency through Whole-Genome Sequencing: Implications for Cost-Effective Care.

D-Bifunctional protein deficiency, caused by recessive mutations in HSD17B4, is a severe disorder of peroxisomal fatty acid oxidation. Nonspecific clinical features may contribute to diagnostic challenges. We describe a newborn female with infantile-onset seizures and nonspecific mild dysmorphisms who underwent extensive genetic workup that resulted in the detection of a novel homozygous mutation (c.302+1_4delGTGA) in the HSD17B4 gene, consistent with a diagnosis of D-bifunctional protein deficiency. By comparing the standard clinical workup to diagnostic analysis performed through research-based whole-genome sequencing (WGS), which independently identified the causative mutation, we demonstrated the ability of genomic sequencing to serve as a timely and cost-effective diagnostic tool for the molecular diagnosis of apparent and occult newborn diseases. As genomic sequencing becomes more available and affordable, we anticipate that WGS and related omics technologies will eventually replace the traditional tiered approach to newborn diagnostic workup.

First independent replication of the involvement of LARS2 in Perrault syndrome by whole-exome sequencing of an Italian family.

Perrault syndrome (MIM #233400) is a rare autosomal recessive disorder characterized by ovarian dysgenesis and primary ovarian insufficiency in females, and progressive hearing loss in both genders. Recently, mutations in five genes (HSD17B4, HARS2, CLPP, LARS2 and C10ORF2) were found to be responsible for Perrault syndrome, although they do not account for all cases of this genetically heterogeneous condition. We used whole-exome sequencing to identify pathogenic variants responsible for Perrault syndrome in an Italian pedigree with two affected siblings. Both patients were compound heterozygous for two novel missense variants within the mitochondrial leucyl-tRNA synthetase (LARS2): NM_015340.3:c.899C>T(p.Thr300Met) and c.1912G>A(p.Glu638Lys). Both variants cosegregated with the phenotype in the family. p.Thr300 and p.Glu638 are evolutionarily conserved residues, and are located, respectively, within the editing domain and immediately before the catalytically important KMSKS motif. Homology modeling using as template the E. coli leucyl-tRNA synthetase provided further insights on the possible pathogenic effects of the identified variants. This represents the first independent replication of the involvement of LARS2 mutations in Perrault syndrome, contributing valuable information for the further understanding of this disease.

Novel anticancer agent, SQAP, binds to focal adhesion kinase and modulates its activity.

SQAP is a novel and promising anticancer agent that was obtained by structural modifications from a natural compound. SQAP inhibits angiogenesis in vivo resulting in increased hypoxia and reduced tumor volume. In this study, the mechanism by which SQAP modifies the tumor microenvironment was revealed through the application of a T7 phage display screening. This approach identified five SQAP-binding proteins including sterol carrier protein 2, multifunctional enzyme type 2, proteasomal ubiquitin receptor, UV excision repair protein and focal adhesion kinase (FAK). All the interactions were confirmed by surface plasmon resonance analysis. Since FAK plays an important role in cell turnover and angiogenesis, the influence of SQAP on FAK was the principal goal of this study. SQAP decreased FAK phosphorylation and cell migration in human umbilical vein endothelial cells and A549 cancer cells. These findings suggest that inhibition of FAK phosphorylation works as the mechanism for the anti-angiogenesis activity of SQAP.

Peroxisomal D-bifunctional protein deficiency: First case reports from Slovakia.

D-bifunctional protein deficiency (#OMIM 261515) is a rare autosomal recessive hereditary metabolic disorder causing severe clinical and biochemical abnormalities that are usually fatal in the course of the first years of life. This disease is classified as single enzyme peroxisomal disorder affecting the β-oxidation pathway in this compartment. In this paper we present a full overview of the clinical presentation, magnetic resonance imaging, biochemical and molecular data of two Slovak D-bifunctional protein deficient patients. In the clinical presentation of both patients severe generalized hypotonia, depression of neonatal reflexes, craniofacial dysmorphism and seizures dominated starting from the second day of life. In both patients, who died up to two years of life, we found elevated plasma levels of very long chain fatty acids and we identified the presence of causative mutations in the HSD17B4 gene. In the first case, we found the homozygous mutation c.46G>A, which is responsible for a defect in the dehydrogenase domain. In the second patient, the heterozygous mutations c.1369A>G and c.1516C>T were present and functionally they are related to the hydratase domain of the protein. This combination of mutations in the second patient is very rare and has not been reported until now. The presence of mutations was examined in all family members, and the resulting data were successfully utilized for prenatal diagnosis.

p110Delta Inhibits Monocyte Infiltration by Thioglycollate-Induced Periotoneal Inflammation but Not HCD-Induced Inflammation and Atherosclerosis in APOE KO Mice.

We have previously reported that phosphoinositide 3-kinase p110δ knockout (p110δ KO) diminished the adhesion of leukocytes to capillary venules and suppressed the peritoneal infiltration of leukocytes, both functions that play important roles in atherosclerosis. Therefore, we hypothesized that p110δ deficiency might be protective against atherosclerosis. Apolipoprotein E knockout (ApoE KO) mice were crossed with p110δ KO mice to generate homozygous double knockout mice (ApoE/p110δ DKO). The present study showed that ApoE/p110δ DKO mice fed with a high cholesterol diet (HCD) demonstrated less peritoneal infiltration of leukocytes and monocytes compared with ApoE KO mice after intraperitoneal injection of thioglycollate, an inducer of acute peritoneal inflammation. Unexpectedly, atherosclerosis in the aortic root and in the entire aorta was similar between the ApoE/p110δ DKO and ApoE KO groups. No difference in Mac-3 expression, indicative of macrophage infiltration, was found between the two groups. Further analysis showed that ApoE KO mice chronically fed with HCD had increased levels of total cholesterol, low-density lipoprotein in the blood and counts and percentages of circulating monocytes compared with ApoE KO mice fed with a normal diet. Consistently, the deficiency of p110δ affected neither the counts nor the percentages of monocytes nor the lipid profiles in the blood. The results suggested that p110δ plays an important role in acute but not in chronic inflammation, the latter being included in the early characteristics of atherosclerosis, which might explain the finding that p110δ deficiency fails to inhibit early atherosclerosis.

Exome analysis identified a novel missense mutation in the CLPP gene in a consanguineous Saudi family expanding the clinical spectrum of Perrault Syndrome type-3.

Perrault syndrome (PRLTS) is a clinically and genetically heterogeneous disorder. Both male and female patients suffer from sensory neuronal hearing loss in early childhood, and female patients are characterized by premature ovarian failure and infertility after puberty. Clinical diagnosis may not be possible in early life, because key features of PRLTS, for example infertility and premature ovarian failure, do not appear before puberty. Limb spasticity, muscle weakness, and intellectual disability have also been observed in PRLTS patients. Mutations in five genes, HSD17B4, HARS2, CLPP, LARS2, and C10orf2, have been reported in five subtypes of PRLTS. We discovered a consanguineous Saudi family with the PRLTS3 phenotype showing an autosomal recessive mode of inheritance. The patients had developed profound hearing loss, brain atrophy, and lower limb spasticity in early childhood. For molecular diagnosis, we complimented genome-wide homozygosity mapping with whole exome sequencing analyses and identified a novel homozygous mutation in exon 6 of CLPP at chromosome 19p13.3. To our knowledge, early onset with regression is a unique feature of these PRLTS patients that has not been reported so far. This study broadens the clinical spectrum of PRLTS3.

D-bifunctional protein deficiency: a cause of neonatal onset seizures and hypotonia.

Peroxisomal disorders are classified in two major groups: (1) peroxisome biogenesis disorders and (2) single peroxisomal enzyme/transporter deficiencies. D-bifunctional protein deficiency (OMIM #261515) is included in this last group of rare diseases and leads to an impaired peroxisomal beta-oxidation. D-bifunctional protein deficiencies are divided into four types based on the degree of activity of the 2-enoyl-CoA hydratase and 3-hydroxyacyl-CoA dehydrogenase protein units.

Identification of a chronic non-neurodegenerative microglia activation state in a mouse model of peroxisomal β-oxidation deficiency.

The functional diversity and molecular adaptations of reactive microglia in the chronically inflamed central nervous system (CNS) are poorly understood. We previously showed that mice lacking multifunctional protein 2 (MFP2), a pivotal enzyme in peroxisomal β-oxidation, persistently accumulate reactive myeloid cells in the gray matter of the CNS. Here, we show that the increased numbers of myeloid cells solely derive from the proliferation of resident microglia and not from infiltrating monocytes. We defined the signature of Mfp2(-/-) microglia by gene expression profiling after acute isolation, which was validated by quantitative polymerase reaction (qPCR), immunohistochemical, and flow cytometric analysis. The features of Mfp2(-/-) microglia were compared with those from SOD1(G93A) mice, an amyotrophic lateral sclerosis model. In contrast to the neurodegenerative milieu of SOD1(G93A) spinal cord, neurons were intact in Mfp2(-/-) brain and Mfp2(-/-) microglia lacked signs of phagocytic and neurotoxic activity. The chronically reactive state of Mfp2(-/-) microglia was accompanied by the downregulation of markers that specify the unique microglial signature in homeostatic conditions. In contrast, mammalian target of rapamycin (mTOR) and downstream glycolytic and protein translation pathways were induced, indicative of metabolic adaptations. Mfp2(-/-) microglia were immunologically activated but not polarized to a pro- or anti-inflammatory phenotype. A peripheral lipopolysaccharide challenge provoked an exaggerated inflammatory response in Mfp2(-/-) brain, consistent with a primed state. Taken together, we demonstrate that chronic activation of resident microglia does not necessarily lead to phagocytosis nor overt neurotoxicity.

The beta-3 adrenergic agonist (CL-316,243) restores the expression of down-regulated fatty acid oxidation genes in type 2 diabetic mice.

The hallmark of Type 2 diabetes (T2D) is hyperglycemia, although there are multiple other metabolic abnormalities that occur with T2D, including insulin resistance and dyslipidemia. To advance T2D prevention and develop targeted therapies for its treatment, a greater understanding of the alterations in metabolic tissues associated with T2D is necessary. The aim of this study was to use microarray analysis of gene expression in metabolic tissues from a mouse model of pre-diabetes and T2D to further understand the metabolic abnormalities that may contribute to T2D. We also aimed to uncover the novel genes and pathways regulated by the insulin sensitizing agent (CL-316,243) to identify key pathways and target genes in metabolic tissues that can reverse the diabetic phenotype.