Search PubMed⌕ Search

Biomedical subjects

Hans Voshol

Publications and source records attributed to Hans Voshol.

10 recordsLinked to original sources
PubMed2026

BRD9 Degraders Unleash GBAF Chromatin Remodeling Activity in Synovial Sarcoma.

UNLABELLED: Synovial sarcoma incorporates the SS18::SSX fusion oncoprotein into GLTSCR1-containing BRG1/BRM and associated factors (GBAF) complexes, which confers a dependency on the GBAF subunit BRD9. However, synovial sarcoma clinical trials with multiple BRD9 degraders failed to achieve clinically impactful remissions. In this study, we identified a mechanistic framework to explain these results. BRD9 depletion served to blunt proliferation in synovial sarcoma harboring minimal genomic alterations, rare in trial participants. In cultured cells, xenografts, and recombinant-purified complexes, BRD9 loss did not affect GBAF assembly. Although BRD9 degradation in synovial sarcoma reduced GBAF enrichment at target loci, BRD9-less complexes maintained or increased chromatin accessibility and associated gene transcription. Biochemical assays with purified recombinant GBAF demonstrated increased nucleosome sliding in the absence of BRD9. Together, these findings show that BRD9 restrains GBAF activity, with BRD9 degradation increasing enzymatic remodeling and target gene expression by fusion oncoprotein-distributed GBAFs in synovial sarcoma. This subtle epigenetic disturbance creates a low hurdle for synovial sarcoma to surpass, limiting the therapeutic efficacy of BRD9 degraders. SIGNIFICANCE: BRD9 represses the GBAF chromatin remodeling complex, which causes enhanced rather than disrupted SS18::SSX complex activity following BRD9 degradation and explains the lack of efficacy of pharmacological BRD9 degraders in synovial sarcoma.

Sarcoma, Synovial↗
PubMed2007

Reduced susceptibility of Haemophilus influenzae to the peptide deformylase inhibitor LBM415 can result from target protein overexpression due to amplified chromosomal def gene copy number.

Previous genetic analysis of Haemophilus influenzae revealed two mechanisms associated with decreased susceptibility to the novel peptide deformylase inhibitor LBM415: AcrAB-TolC-mediated efflux and Fmt bypass, resulting from mutations in the pump repressor gene acrR and in the fmt gene, respectively. We have isolated an additional mutant, CDS23 (LBM415 MIC, 64 microg/ml versus 4 microg/ml against the parent strain NB65044) that lacks mutations in the acrR or fmt structural genes or in the gene encoding Def, the intracellular target of LBM415. Western immunoblot analysis, two-dimensional gel electrophoresis, and tryptic digestion combined with mass spectrometric identification showed that the Def protein was highly overexpressed in the mutant strain. Consistent with this, real-time reverse transcription-PCR revealed a significant increase in def transcript titer. No mutations were found in the region upstream of def that might account for altered expression; however, pulsed-field gel electrophoresis suggested that a genetic rearrangement of the region containing def had occurred. Using a combination of PCR, sequencing, and Southern blot analyses, it was determined that the def gene had undergone copy number amplification, explaining the high level of target protein expression. Inactivation of the AcrAB-TolC efflux pump in this mutant increased susceptibility 16-fold, highlighting the role of efflux in exacerbating the overall reduced susceptibility resulting from target overexpression.

Amidohydrolases↗
PubMed2006

Identification of apolipoprotein A-I as a "STOP" signal for myopia.

Good visual acuity requires that the axial length of the ocular globe is matched to the refractive power of the cornea and lens to focus the images of distant objects onto the retina. During the growth of the juvenile eye, this is achieved through the emmetropization process that adjusts the ocular axial length to compensate for the refractive changes that occur in the anterior segment. A failure of the emmetropization process can result in either excessive or insufficient axial growth, leading to myopia or hyperopia, respectively. Emmetropization is mainly regulated by the retina, which generates two opposite signals: "GO/GROW" signals to increase axial growth and "STOP" signals to block it. The presence of GO/GROW and STOP signals was investigated by a proteomics analysis of the retinas from chicken with experimental myopia and hyperopia. Of 18 differentially expressed proteins that were identified, five displayed an expression profile corresponding to GO/GROW signals, and two corresponded to STOP signals. Western blotting confirmed that apolipoprotein A-I (apoA-I) has the characteristics of a STOP signal both in the retina as well as in the fibrous sclera. In accordance with this, intraocular application of the peroxisome proliferator-activated receptor alpha agonist GW7647 resulted in up-regulation of apoA-I levels and in a significant reduction of experimental myopia. In conclusion, using a comprehensive functional proteomics analysis of chicken ocular growth models we identified targets for ocular growth control. The correlation of elevated apoA-I levels with reduced ocular axial growth points toward a functional relationship with the observed morphological changes of the eye.

Animals↗
PubMed2004

Neuroproteomics: expression profiling of the brain's proteomes in health and disease.

The term "proteome" describes the protein complement of a genome. Proteomes of cells are dynamic and are directly affected by environmental factors, such as stress and/or drug treatment, or as a result of aging and disease. One of the distinct advantages of proteomic analysis, not attainable with RNA expression data, is the ability to fractionate the cell's proteins into various subpopulations. In neuroscience, "neuromics" (proteomics in the central nervous system) is in its infancy, with a paucity of studies in the context of the brain. One of the objectives of this review is to illustrate the potential of neuromics to profile differences in the distribution of thousands of proteins as a function of disease markers. We have previously used this approach to determine the effects of varied postmortem interval in examining human brain tissue and to identify biomarkers. Here we review proteomic studies of schizophrenia, Alzheimer's disease, and Parkinson's disease. Experimental results regarding Parkinson's disease are presented to illustrate the potential of neuromics to identify pathways of pathogenesis and novel therapeutic targets.

Alzheimer Disease↗
PubMed2003

Proteomics-based target identification: bengamides as a new class of methionine aminopeptidase inhibitors.

LAF389 is a synthetic analogue of bengamides, a class of marine natural products that produce inhibitory effects on tumor growth in vitro and in vivo. A proteomics-based approach has been used to identify signaling pathways affected by bengamides. LAF389 treatment of cells resulted in altered mobility of a subset of proteins on two-dimensional gel electrophoresis. Detailed analysis of one of the proteins, 14-3-3gamma, showed that bengamide treatment resulted in retention of the amino-terminal methionine, suggesting that bengamides directly or indirectly inhibited methionine aminopeptidases (MetAps). Both known MetAps are inhibited by LAF389. Short interfering RNA suppression of MetAp2 also altered amino-terminal processing of 14-3-3gamma. A high resolution structure of human MetAp2 co-crystallized with a bengamide shows that the compound binds in a manner that mimics peptide substrates. Additionally, the structure reveals that three key hydroxyl groups on the inhibitor coordinate the di-cobalt center in the enzyme active site.

14-3-3 Proteins↗
PubMed2003

Proteomics in the discovery of new therapeutic targets for psychiatric disease.

In terms of impact on and cost to society psychiatric disorders are among the most important health problems of today. Current estimates from the US suggest that the collective cost of psychiatric diseases could amount to one-third of the total health care budget with a cumulative lifetime prevalence of 30%. While undoubtedly improvements have been made in the diagnosis and treatment of at least the symptoms of mental illness, there has been frustratingly little progress in elucidating the molecular mechanisms. However, a fundamentally different approach to study molecular mechanisms of psychiatric diseases is emerging as a result of technological advances in expression profiling methods. This comprises the investigation of the expressed disease 'phenotypes', developing from the differential gene and protein expression in the central nervous system as a result of the complex interaction between genetic predisposition and environmental modulation. This paper will focus on proteomics, expression profiling at the protein level, reviewing some of the available tools and their application in the molecular analysis of psychiatric disease.

Antipsychotic Agents↗
PubMed2002

Preparative two-dimensional gel electrophoresis at alkaline pH using narrow range immobilized pH gradients.

A reproducible high-resolution protein separation method is the basis for a successful differential proteome analysis. Of the techniques currently available, two-dimensional gel electrophoresis is most widely used, because of its robustness under various experimental conditions. With the introduction of narrow range immobilized pH gradient (IPG) strips (also referred to as ultra-zoom gels) in the first dimension, the depth of analysis, i.e. the number of proteins that can be resolved, has increased substantially. However, for poorly understood reasons isoelectric focusing on ultra-zoom gels in the alkaline region above pH 7 has suffered from problems with resolution and reproducibility. To tackle these difficulties we have optimized the separation of semipreparative amounts of proteins on alkaline IPG strips by focusing on two important phenomena: counteracting water transport during isoelectric focusing and migration of dithiothreitol (DTT) in alkaline pH gradients. The first problem was alleviated by the addition of glycerol and isopropanol to the focusing medium, leading to a significant improvement in the resolution above pH 7. Even better results were obtained by the introduction of excess of the reducing agent DTT at the cathode. With these adaptations together with an optimized composition of the IPG strip, separation efficiency in the pH 6.2-8.2 range is now comparable to the widely used acidic ultra-zoom gels. We further demonstrated the usefulness of these modifications up to pH 9.5, although further improvements are still needed in that range. Thus, by extending the range covered by conventional ultra-zoom gels, the depth of analysis of two-dimensional gel electrophoresis can be significantly increased, underlining the importance of this method in differential proteomics.

2-Propanol↗
PubMed2002

Identification of a peptide mimic of the L2/HNK-1 carbohydrate epitope.

The L2/HNK-1 carbohydrate is carried by many neural recognition molecules and is involved in neural cell interactions during development, regeneration in the peripheral nervous system, synaptic plasticity, and autoimmune-based neuropathies. Its key structure consists of a sulfated glucuronic acid linked to lactosaminyl residues. Because of its biological importance but limited availability, the phage display method was used to isolate a collection of peptide mimics that bind specifically to an L2/HNK-1 antibody. The phages isolated from a 15-mer peptide library by adsorption to this antibody share a consensus sequence of amino acids. The peptide mimicked several important functions of the L2/HNK-1 carbohydrate, such as binding to motor neurons in vitro, and preferential promotion of in vitro neurite outgrowth from motor axons compared with sensory neurons. A scrambled version of the peptide had no activity. The combined observations indicate that we have isolated a mimic of the L2/HNK-1 carbohydrate that is able to act as its functional substitute.

Amino Acid Sequence↗
PubMedDate not supplied

Evaluation of biomarker discovery approaches to detect protein biomarkers of acute renal allograft rejection.

Management of host responses to allografts by immunosuppressive therapy is the cornerstone of transplantation medicine, but it is still deficient in one important element: biomarkers that are readily accessible and predict the fate of the transplant early, specifically, and reliably. Using a Brown Norway (BN)-to-Lewis rat renal allograft model of kidney transplantation, this study aims at evaluating two proteomic approaches to discover biomarkers for acute rejection: SELDI-MS technology and 2D gel electrophoresis combined with mass spectrometry. Several novel potential serum biomarkers have been identified for follow up. Overall, the conclusion is that apparently at the serum protein level, dramatic changes only occur at a stage where kidney function is already severely affected. Multivariate analysis of serum profiles suggests that there is an ensemble of subtle changes, comprising a proteomic signature of acute rejection at an early stage, a more detailed evaluation of which might provide novel opportunities for the diagnosis of acute rejection. Profiling of the excreted proteins indicates that urine might even present the earliest signs of the rejection process.

Animals↗