Biology subjects

Hohenstein, P.

Publications and source records attributed to Hohenstein, P..

8 recordsLinked to original sources

bioRxiv2025

Molecular characterization of Cdh12-SCON conditional knockout mice reveals unexpected splicing changes

Functional validation of candidate genes in congenital anomalies of the kidneys and urinary tract (CAKUT) and other disorders is essential for translating genetic discoveries into clinical applications. Conditional knockout mouse models are indispensable for studying gene function in complex organ systems. The Short Conditional intrON (SCON) system accelerates the generation of such models by inserting the artificial SCON into a coding exon. SCON is designed to splice out after transcription, without affecting gene expression. Upon Cre activity, SCON is converted into the {Delta}SCON allele which cannot be spliced out, introducing premature termination codons (PTCs) to inactivate the gene. Previous validation of the SCON system in mice has focused primarily on phenotypic outcomes. Here, we provide a molecular characterization of the SCON system in Cdh12 - a candidate gene implicated in kidney damage in CAKUT. We found that both Cdh12SCON and Cdh12{Delta}SCON alleles caused unintended skipping of the exon downstream of the insertion site, culminating in a frameshift and PTC. Consequently, the Cdh12SCON allele led to a ~25% reduction in mRNA expression, indicating that it was not transcriptionally inert as designed. Despite unintended exon skipping, the Cdh12{Delta}SCON allele still effectively suppressed mRNA expression. These findings reveal previously unrecognized splicing artifacts of the SCON system and underscore the need for transcript-level characterization before utilizing artificial intron-based conditional alleles for functional studies.

genetics↗

bioRxiv2025

Four new Duchenne muscular dystrophy mouse models with clinically relevant exon deletions in the human DMD gene

Mutation specific therapeutic approaches, like exon skipping or gene-editing, hold promise for the treatment of Duchenne muscular dystrophy (DMD). Translatability of preclinical studies investigating these approaches could greatly be improved through the use of humanized mouse models, as these allow preclinical testing of human specific sequences. We developed four novel humanized DMD mouse models with either a deletion of exon 44, 45, 51 or 53 in the human DMD gene, in a mouse dystrophin negative background (mdx mouse; exon 23 nonsense mutation). Our optimized prescreening pipeline allowed us to do so very efficiently with the CRISPR-Cas9 technology. We confirmed either complete lack of dystrophin, or expression of trace levels, which led to development of muscle pathology consisting of muscle fiber de-, and regeneration, inflammation and fibrosis in young adult mice. Intramuscular treatment with vivo-morpholinos targeting a flanking exon induced exon skipping in the DMD strains, which restored the disrupted open reading frame and subsequently dystrophin expression. This validates these models as valuable tools for preclinical studies investigating human sequence specific therapeutic approaches for DMD. Summary statementHumanized Duchenne muscular dystrophy mouse models were created with deletions of exon 44, 45, 51 or 53 in the human DMD gene. These dystrophic models allow preclinical testing of human-specific dystrophin restoring approaches.

neuroscience↗

bioRxiv2025

Genotype-phenotype correlations in Wilms tumor initiation.

Wilms tumor, the most common pediatric kidney cancer, arises from abnormal embryonic kidney development. Therapy resistance and tumor recurrence remain major challenges, likely driven by the presence of Cancer Stem Cells (CSCs). Here, we elucidate the earliest pathogenic events in genetically engineered mouse models exhibiting loss of Wt1 or LIN28B overexpression, two Wilms tumor driver genes. Loss of Wt1 leads to a disturbance of lineage identity of the mutant cells, whereas LIN28B leads to a disturbed transition between uninduced and induced NPC (nephron progenitor cell) state. In both cases the appearance of cells positive for all four Wilms tumor cancer stem cell markers is the result of the tumor initiating mutation. The existence of genotype-phenotype correlations in primary developmental phenotypes and cancer stem cell expression patterns has important implications for therapeutic opportunities and requirements.

developmental biology↗

bioRxiv2023

Mutational scanning reveals oncogenic CTNNB1 mutations have diverse effects on signalling and clinical traits

CTNNB1, the gene encoding {beta}-catenin, is a frequent target for oncogenic mutations activating the canonical Wnt signalling pathway, typically via missense mutations within a degron hotspot motif in exon 3. Here, we combine saturation genome editing with a fluorescent reporter assay to quantify signalling phenotypes for all 342 missense mutations in the mutation hotspot, including 74 recurrent mutations reported in over 6000 tumours. Our data define the genetic requirements for {beta}-catenin degron function and reveal diverse levels of signal activation among known driver mutations. Tumorigenesis in different human tissues involves selection for CTNNB1 mutations spanning distinct ranges of effect size. In hepatocellular carcinoma, mutations that activate {beta}-catenin relatively weakly are associated with worse prognosis compared to stronger activating mutations, despite greater immune cell infiltration in the tumour microenvironment. Our work therefore provides a resource to understand mutational diversity within a pan-cancer mutation hotspot, with potential implications for targeted therapy.

cancer biology↗

bioRxiv2023

Characterization of alternative splicing in high-risk Wilms tumors

The significant heterogeneity of Wilms tumors between different patients is thought to arise from genetic and epigenetic distortions that occur during various stages of fetal kidney development in a way that is poorly understood. To address this, we characterized the heterogeneity of alternative mRNA splicing in Wilms tumors using a publicly available RNAseq dataset of high-risk Wilms tumors and normal kidney samples. Through Pareto task inference and cell deconvolution, we found that the tumors and normal kidney samples are organized according to progressive stages of kidney development within a triangle-shaped region in latent space, whose vertices, or "archetypes," resemble the cap mesenchyme, the nephrogenic stroma, and epithelial tubular structures of the fetal kidney. We identified a set of genes that are alternatively spliced between tumors located in different regions of latent space and found that many of these genes are associated with the Epithelial to Mesenchymal Transition (EMT) and muscle development. Using motif enrichment analysis, we identified putative splicing regulators, some of which are associated with kidney development. Our findings provide new insights into the etiology of Wilms tumors and suggest that specific splicing mechanisms in early stages of development may contribute to tumor development in different patients.

cancer biology↗

bioRxiv2022

Characterization of the continuous transcriptional heterogeneity in Wilms tumors using unsupervised machine learning

Wilms tumors are pediatric malignancies that are thought to arise from faulty kidney development. To date, the course of treatment depends on manual histopathological classification which is difficult since the tumors differ between patients in a continuous manner. Here, we used three computational approaches to characterize the continuous heterogeneity of Wilms tumors. We first chose a published dataset of microarray gene expression measurements from high-risk blastemal-type Wilms tumors. Then, we used Pareto Task Inference to show that the tumors form a triangle-shaped continuum in latent space that is bounded by three tumor archetypes with "stromal", "epithelial", and "blastemal" characteristics, that resemble the un-induced mesenchyme, the Cap mesenchyme, and early epithelial structures of the fetal kidney. We confirmed this by fitting a generative probabilistic "grade of membership" model whereby each tumor is represented as a unique mixture of three hidden "topics" with blastemal, stromal, and epithelial characteristics. Finally, we used cellular deconvolution to show that each tumor is composed of a unique mixture of cell populations resembling the un-induced mesenchyme, the cap mesenchyme, and the early epithelial structures of the fetal kidney. We anticipate that these methodologies will pave the way for more quantitative strategies for tumor stratification and classification.

cancer biology↗

bioRxiv2021

OX40 agonism enhances efficacy of PD-L1 checkpoint blockade by shifting the cytotoxic T cell differentiation spectrum

Immune checkpoint therapy (ICT) has the potency to eradicate cancer but the mechanisms that determine effective versus non-effective therapy-induced immune responses are not fully understood. Here, using high-dimensional single-cell profiling we examined whether T cell states in the blood circulation could predict responsiveness to a combined ICT, sequentially targeting OX40 costimulatory and PD-1 inhibitory pathways, which effectively eradicated syngeneic mouse tumors. Unbiased assessment of transcriptomic alterations by single-cell RNA sequencing and profiling of cell-surface protein expression by mass cytometry revealed unique activation states for therapy-responsive CD4+ and CD8+ T cells. Effective ICT elicited T cells with dynamic expression of distinct NK cell and chemokine receptors, and these cells were systemically present in lymphoid tissues and in the tumor. Moreover, NK cell receptor-expressing CD8+ T cells were also present in the peripheral blood of immunotherapy-responsive cancer patients. Targeting of the NK cell and chemokine receptors in tumor-bearing mice showed their functional importance for therapy-induced anti-tumor immunity. These findings provide a better understanding of ICT and highlight the use of dynamic biomarkers on effector CD4+ and CD8+ T cells to improve cancer immunotherapy.

immunology↗

bioRxiv2019

Single-cell RNA sequencing reveals mRNA splice isoform switching during kidney development

During mammalian kidney development, nephron progenitors undergo a mesenchymal to epithelial transition and eventually differentiate into the various tubular segments of the nephron. Recently, the different cell types in the developing kidney were characterized using the Dropseq single cell RNA sequencing technology for measuring gene expression from thousands of individual cells. However, many genes can also be alternatively spliced and this creates an additional layer of heterogeneity. We therefore used full transcript length single-cell RNA sequencing to obtain the transcriptomes of 544 individual cells from mouse embryonic kidneys. We first used gene expression levels to identify each cell type. Then, we comprehensively characterized the splice isoform switching that occurs during the transition between mesenchymal and epithelial cellular states and identified several putative splicing regulators, including the genes Esrp1/2 and Rbfox1/2. We anticipate that these results will improve our understanding of the molecular mechanisms involved in kidney development.

genomics↗