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Louise van der Weyden

Publications and source records attributed to Louise van der Weyden.

15 recordsLinked to original sources
PubMed2025

Ancestry and somatic profile predict acral melanoma origin and prognosis.

Acral melanoma, which is not ultraviolet (UV)-associated, is the most common type of melanoma in several low- and middle-income countries including Mexico. Latin American samples are significantly underrepresented in global cancer genomics studies, which directly affects patients in these regions as it is known that cancer risk and incidence may be influenced by ancestry and environmental exposures. To address this, we characterise the genome and transcriptome of 123 acral melanoma tumours from 92 Mexican patients, a population notable because of its genetic admixture. Compared with other studies of melanoma, we found fewer frequent mutations in classical driver genes such as BRAF, NRAS or NF1. While most patients had predominantly Amerindian genetic ancestry, those with higher European ancestry had increased frequency of BRAF mutations and a lower median number of structural variants. The tumours with activating BRAF mutations have a transcriptional profile more similar to cutaneous non-volar melanocytes, suggesting that acral melanomas in these patients may arise from a distinct cell of origin compared to other tumours arising in these locations. KIT mutations were found in a subset of these tumours, and quadruple wild-type samples (non BRAF/NRAS/NF1/KIT) differed from mutated samples in their structural genomic profile and overall and recurrence-free survival patterns. Transcriptional profiling defined three expression clusters; these characteristics were associated with recurrence-free and overall survival. We highlight potential novel low-frequency drivers, such as PTPRJ, NF2 and RDH5. Our study enhances knowledge of this understudied disease and underscores the importance of including samples from diverse ancestries in cancer genomics studies.

Journal Article↗
PubMed2006

Renin enhancer is critical for control of renin gene expression and cardiovascular function.

The important cardiovascular regulator renin contains a strong in vitro enhancer 2.7 kb upstream of its gene. Here we tested the in vivo role of the mouse Ren-1c enhancer. In renin-expressing As4.1 cells stably transfected with Ren-1c promoter with or without enhancer, expression of linked beta-geo reporter, stable expression, and colony formation were dependent on the presence of the enhancer. We then generated mice carrying a targeted deletion of the enhancer (REKO mice) and found marked depletion of renin in renal juxtaglomerular and submandibular ductal cells, as well as hyperplasia of macula densa cells. Plasma creatinine was increased, but electrolytes were normal. Male REKO mice implanted with telemetry devices had 9 +/- 1 mm Hg lower mean arterial pressure (p < 0.001), which was partly normalized by a high NaCl diet. Locomotor activity was lower, and baroreflex sensitivity was normal. Markedly reduced mean arterial pressure variability in the midfrequency band indicated a contribution of reduced sympathetic vasomotor tone to the hypotension. In conclusion, the renin enhancer is critical for renin gene expression and physiological sequelae, including response to alteration in salt intake. The REKO mouse may be useful as a low renin expression model.

Animals↗
PubMed2006

Geminin is essential to prevent endoreduplication and to form pluripotent cells during mammalian development.

In multicellular eukaryotes, geminin prevents overreplication of DNA in proliferating cells. Here, we show that genetic ablation of geminin in the mouse prevents formation of inner cell mass (ICM) and causes premature endoreduplication at eight cells, rather than 32 cells. All cells in geminin-deficient embryos commit to the trophoblast cell lineage and consist of trophoblast giant cells (TGCs) only. Geminin is also down-regulated in TGCs of wild-type blastocysts during S and gap-like phases by proteasome-mediated degradation, suggesting that loss of geminin is part of the mechanism regulating endoreduplication.

Animals↗
PubMed2006

Loss of TSLC1 causes male infertility due to a defect at the spermatid stage of spermatogenesis.

Tumor suppressor of lung cancer 1 (TSLC1), also known as SgIGSF, IGSF4, and SynCAM, is strongly expressed in spermatogenic cells undergoing the early and late phases of spermatogenesis (spermatogonia to zygotene spermatocytes and elongating spermatids to spermiation). Using embryonic stem cell technology to generate a null mutation of Tslc1 in mice, we found that Tslc1 null male mice were infertile. Tslc1 null adult testes showed that spermatogenesis had arrested at the spermatid stage, with degenerating and apoptotic spermatids sloughing off into the lumen. In adult mice, Tslc1 null round spermatids showed evidence of normal differentiation (an acrosomal cap and F-actin polarization indistinguishable from that of wild-type spermatids); however, the surviving spermatozoa were immature, malformed, found at very low levels in the epididymis, and rarely motile. Analysis of the first wave of spermatogenesis in Tslc1 null mice showed a delay in maturation by day 22 and degeneration of round spermatids by day 28. Expression profiling of the testes revealed that Tslc1 null mice showed increases in the expression levels of genes involved in apoptosis, adhesion, and the cytoskeleton. Taken together, these data show that Tslc1 is essential for normal spermatogenesis in mice.

Animals↗
PubMed2006

Mouse chromosome engineering for modeling human disease.

Chromosomal rearrangements are frequently in humans and can be disease-associated or phenotypically neutral. Recent technological advances have led to the discovery of copy-number changes previously undetected by cytogenetic techniques. To understand the genetic consequences of such genomic changes, these mutations need to be modeled in experimentally tractable systems. The mouse is an excellent organism for this analysis because of its biological and genetic similarity to humans, and the ease with which its genome can be manipulated. Through chromosome engineering, defined rearrangements can be introduced into the mouse genome. The resulting mouse models are leading to a better understanding of the molecular and cellular basis of dosage alterations in human disease phenotypes, in turn opening new diagnostic and therapeutic opportunities.

Animals↗
PubMed2006

Functional knockout of the matrilin-3 gene causes premature chondrocyte maturation to hypertrophy and increases bone mineral density and osteoarthritis.

Mutations in the gene encoding matrilin-3 (MATN3), a noncollagenous extracellular matrix protein, have been reported in a variety of skeletal diseases, including multiple epiphyseal dysplasia, which is characterized by irregular ossification of the epiphyses and early-onset osteoarthritis, spondylo-epimetaphyseal dysplasia, and idiopathic hand osteoarthritis. To assess the role of matrilin-3 in the pathogenesis of these diseases, we generated Matn3 functional knockout mice using embryonic stem cell technology. In the embryonic growth plate of the developing long bones, Matn3 null chondrocytes prematurely became prehypertrophic and hypertrophic, forming an expanded zone of hypertrophy. This expansion was attenuated during the perinatal period, and Matn3 homozygous null mice were viable and showed no gross skeletal malformations at birth. However, by 18 weeks of age, Matn3 null mice had a significantly higher total body bone mineral density than Matn1 null mice or wild-type littermates. Aged Matn3 null mice were much more predisposed to develop severe osteoarthritis than their wild-type littermates. Here, we show that matrilin-3 plays a role in modulating chondrocyte differentiation during embryonic development, in controlling bone mineral density in adulthood, and in preventing osteoarthritis during aging. The lack of Matn3 does not lead to postnatal chondrodysplasia but accounts for higher incidence of osteoarthritis.

Aging↗
PubMed2005

A genome-wide, end-sequenced 129Sv BAC library resource for targeting vector construction.

The majority of gene-targeting experiments in mice are performed in 129Sv-derived embryonic stem (ES) cell lines, which are generally considered to be more reliable at colonizing the germ line than ES cells derived from other strains. Gene targeting is reliant on homologous recombination of a targeting vector with the host ES cell genome. The efficiency of recombination is affected by many factors, including the isogenicity (H. te Riele et al., 1992, Proc. Natl. Acad. Sci. USA 89, 5128-5132) and the length of homologous sequence of the targeting vector and the location of the target locus. Here we describe the double-end sequencing and mapping of 84,507 bacterial artificial chromosomes (BACs) generated from AB2.2 ES cell DNA (129S7/SvEvBrd-Hprtb-m2). We have aligned these BACs against the mouse genome and displayed them on the Ensembl genome browser, DAS: 129S7/AB2.2. This library has an average insert size of 110.68 kb and average depth of genome coverage of 3.63- and 1.24-fold across the autosomes and sex chromosomes, respectively. Over 97% of the mouse genome and 99.1% of Ensembl genes are covered by clones from this library. This publicly available BAC resource can be used for the rapid construction of targeting vectors via recombineering. Furthermore, we show that targeting vectors containing DNA recombineered from this BAC library can be used to target genes efficiently in several 129-derived ES cell lines.

Animals↗
PubMed2005

Null and conditional semaphorin 3B alleles using a flexible puroDeltatk loxP/FRT vector.

In neural development, Semaphorin 3B (SEMA3B) is thought to play a role in guiding axons by repulsion. In nonneuronal tissue, SEMA3B has been postulated to be a tumor suppressor gene of lung and breast cancer. Much of the understanding of the function of members of the SEMA3 family has come from targeted deletion of these genes in mice (Sema3A, Sema3C, and Sema3F). Thus, targeted deletion of Sema3B in mice would prove invaluable in dissecting out its functions. To allow for maximum gene-targeting flexibility, we developed a generic targeting vector, pFlexible, containing the positive/negative selectable marker puroDeltatk and loxP and FRT recombination sites, and used it to target Sema3B in ES cells. Flpe- and Cre-mediated recombination in vitro generated ES cell lines that contained a conditional or null Sema3B allele, respectively, which were established as homozygous alleles in mice. Analysis of Sema3B null mice showed they were viable, fertile, and displayed no overt pathological abnormalities, suggesting an inherent correction mechanism or level of redundancy between the class 3 semaphorins. This targeting vector system has broad applicability in any knockout experiment and provides a flexible approach for the generation of modified alleles in mice.

Alleles↗
PubMed2005

BRCTx is a novel, highly conserved RAD18-interacting protein.

The BRCT domain is a highly conserved module found in many proteins that participate in DNA damage checkpoint regulation, DNA repair, and cell cycle control. Here we describe the cloning, characterization, and targeted mutagenesis of Brctx, a novel gene with a BRCT motif. Brctx was found to be expressed ubiquitously in adult tissues and during development, with the highest levels found in testis. Brctx-deficient mice develop normally, show no pathological abnormalities, and are fertile. BRCTx binds to the C terminus of hRAD18 in yeast two-hybrid and immunoprecipitation assays and colocalizes with this protein in the nucleus. Despite this, Brctx-deficient murine embryonic fibroblasts (MEFs) do not show overt sensitivity to DNA-damaging agents. MEFs from Brctx-deficient embryos grow at a similar rate to wild-type MEF CD4/CD8 expressions, and the cell cycle parameters of thymocytes from wild-type and Brctx knockout animals are indistinguishable. Intriguingly, the BRCT domain of BRCTx is responsible for mediating its localization to the nucleus and centrosome in interphase cells. We conclude that, although highly conserved, Brctx is not essential for the above-mentioned processes and may be redundant.

Amino Acid Sequence↗
PubMed2004

Mutagenic insertion and chromosome engineering resource (MICER).

Embryonic stem cell technology revolutionized biology by providing a means to assess mammalian gene function in vivo. Although it is now routine to generate mice from embryonic stem cells, one of the principal methods used to create mutations, gene targeting, is a cumbersome process. Here we describe the indexing of 93,960 ready-made insertional targeting vectors from two libraries. 5,925 of these vectors can be used directly to inactivate genes with an average targeting efficiency of 28%. Combinations of vectors from the two libraries can be used to disrupt both alleles of a gene or engineer larger genomic changes such as deletions, duplications, translocations or inversions. These indexed vectors constitute a public resource (Mutagenic Insertion and Chromosome Engineering Resource; MICER) for high-throughput, targeted manipulation of the mouse genome.

Animals↗
PubMed2003

HADHB, HuR, and CP1 bind to the distal 3'-untranslated region of human renin mRNA and differentially modulate renin expression.

Production of renin is critically dependent on modulation of REN mRNA stability. Here we sought to elucidate the molecular mechanisms involved. Transfections of renin-expressing Calu-6 cells with reporter constructs showed that a cis-acting 34-nucleotide AU-rich "renin stability regulatory element" in the REN 3'-untranslated region (3'-UTR) contributes to basal REN mRNA instability. Yeast three-hybrid screening with the REN 3'-UTR as bait isolated HADHB (hydroxyacyl-CoA dehydrogenase/3-ketoacyl-CoA thiolase/enoyl-CoA hydratase (trifunctional protein) beta-subunit) as a novel REN mRNA-binding protein. Recombinant HADHB bound specifically to the 3'-UTR of REN mRNA, as did the known mRNA stabilizers HuR and CP1 (poly(C)-binding protein-1). This required the renin stability regulatory element. Forskolin, which augments REN mRNA stability in Calu-6 cells, increased binding of several proteins, including HuR and CP1, to the REN 3'-UTR, whereas 4-bromocrotonic acid, a specific thiolase inhibitor, decreased binding and elevated renin protein levels. Upon decreasing HADHB mRNA with RNA interference, renin protein and mRNA stability increased, whereas RNA interference against HuR caused these to decrease. Immunoprecipitation and reverse transcription-PCR of Calu-6 extracts confirmed that HADHB, HuR, and CP1 each associate with REN mRNA in vivo. Intracellular imaging revealed distinct localization of HADHB to mitochondria, HuR to nuclei, and CP1 throughout the cell. Immunohistochemistry demonstrated enrichment of HADHB in renin-producing renal juxtaglomerular cells. In conclusion, HADHB, HuR, and CP1 are novel REN mRNA-binding proteins that target a cis-element in the 3'-UTR of REN mRNA and regulate renin production. cAMP-mediated increased REN mRNA stability may involve stimulation of HuR and CP1, whereas REN mRNA decay may involve thiolase-dependent pathways.

3' Untranslated Regions↗
PubMed2003

The structure of the zinc finger domain from human splicing factor ZNF265 fold.

Identification of the protein domains that are responsible for RNA recognition has lagged behind the characterization of protein-DNA interactions. However, it is now becoming clear that a range of structural motifs bind to RNA and their structures and molecular mechanisms of action are beginning to be elucidated. In this report, we have expressed and purified one of the two putative RNA-binding domains from ZNF265, a protein that has been shown to bind to the spliceosomal components U1-70K and U2AF35 and to direct alternative splicing. We show that this domain, which contains four highly conserved cysteine residues, forms a stable, monomeric structure upon the addition of 1 molar eq of Zn(II). Determination of the solution structure of this domain reveals a conformation comprising two stacked beta-hairpins oriented at approximately 80 degrees to each other and sandwiching the zinc ion; the fold resembles the zinc ribbon class of zinc-binding domains, although with one less beta-strand than most members of the class. Analysis of the structure reveals a striking resemblance to known RNA-binding motifs in terms of the distribution of key surface residues responsible for making RNA contacts, despite a complete lack of structural homology. Furthermore, we have used an RNA gel shift assay to demonstrate that a single crossed finger domain from ZNF265 is capable of binding to an RNA message. Taken together, these results define a new RNA-binding motif and should provide insight into the functions of the >100 uncharacterized proteins in the sequence data bases that contain this domain.

Amino Acid Sequence↗
PubMed2002

Tools for targeted manipulation of the mouse genome.

In the postgenomic era the mouse will be central to the challenge of ascribing a function to the 40,000 or so genes that constitute our genome. In this review, we summarize some of the classic and modern approaches that have fueled the recent dramatic explosion in mouse genetics. Together with the sequencing of the mouse genome, these tools will have a profound effect on our ability to generate new and more accurate mouse models and thus provide a powerful insight into the function of human genes during the processes of both normal development and disease.

Animals↗