Biology subjects

Klatt, K.

Publications and source records attributed to Klatt, K..

4 recordsLinked to original sources

bioRxiv2025

Lipodystrophy and recovery are mediated by the Wnt/lipogenesis axis during skin fibrosis.

Acquired lipodystrophy in the dermal white adipose tissue (DWAT) is a salient feature of skin fibrosis, and is followed by accumulation of extracellular matrix (ECM). Lipodystrophy syndromes, often associated with metabolic co-morbidities, are estimated to affect 1 in 20,000 people. We recently showed that fibrosis-associated lipodystrophy is dependent on sustained Wnt signaling, but the mechanism is unclear. Transcriptomic profiling of mature dermal adipocytes in vivo reveal that Wnt activation downregulates the de novo-lipogenesis (DNL) axis enzymes within 48 hours. We found that protein expression of Fatty Acid Synthase (FASN), a key DNL enzyme, is dependent on sustained Wnt activation in vitro and in vivo. In human systemic sclerosis, FASN mRNA is significantly downregulated during two years of disease. Remarkably, pharmacological inhibition of FASN enzyme during reversal from Wnt induced fibrosis impedes recovery of DWAT lipid content as well as ECM accumulation and topography. All together, we demonstrate that acquired lipodystrophy in the context of skin fibrosis is mediated by a new role of the Wnt-DNL axis. These findings underscore the importance of this pathway in lipodystrophy and fibrosis, opening new avenues for therapeutic targets in skin fibrosis.

cell biology↗

bioRxiv2022

A cross-sectional study of the commercial plant-based landscape across the US, UK and Canada.

As plant-based foods comprise an ever-increasing proportion of the diet, understanding the nutritional composition of these products is critical. In this study we assess the nutritional content of all commercial plant-based products across multiple sectors (supermarkets, fast food & sit down restaurants, food delivery companies and manufacturers) in the US, UK and Canada. We identified 3488 unique products. Across all sectors, 45% of main meals had >15g protein, 60% had <10%kcal from saturated fat; 29% had >10g fibre per meal; 86% had <1000mg sodium. At restaurants, meat-based main meals were significantly higher in protein and sodium compared to vegetarian and vegan meals. The meat-based options were also significantly higher in saturated fat than the vegan but not vegetarian options. We conclude that plant-based items tend to be lower in saturated fat and sodium than their meat-based counterparts but improvements are needed to optimise their nutritional composition.

scientific communication and education↗

bioRxiv2021

Robust designation of meiotic crossover sites by CDK-2 through phosphorylation of the MutSγ complex

Crossover formation is essential for proper segregation of homologous chromosomes during meiosis. Here we show that C. elegans Cyclin-dependent kinase 2 (CDK-2) forms a complex with cyclin-like protein COSA-1 and supports crossover formation by promoting conversion of meiotic double-strand breaks (DSBs) into crossover-specific recombination intermediates. Further, we identify MutS{gamma} component MSH-5 as a CDK-2 phosphorylation target. MSH-5 has a disordered C-terminal tail that contains 13 potential CDK phosphosites and is required to concentrate crossover-promoting proteins at recombination sites. Phosphorylation of the MSH-5 tail appears dispensable in a wild- type background, but when MutS{gamma} activity is partially compromised, crossover formation and retention of CDK-2/COSA-1 at recombination sites are exquisitely sensitive to phosphosite loss. Our data support a model in which robustness of crossover designation reflects a positive feedback mechanism involving CDK-2-mediated phosphorylation and scaffold-like properties of the MSH-5 C-terminal tail, features that combine to promote full recruitment and activity of crossover-promoting complexes.

cell biology↗

bioRxiv2020

Constitutive Androstane Receptor and Hepatitis B Virus X Protein Cooperatively Induce β-catenin-Activated Liver Tumors

Background and AimsThe xenobiotic nuclear receptor Constitutive Androstane Receptor (CAR) is essential for xenobiotic tumor promotion in mouse models. In these models, {beta}-catenin is genetically activated in approximately 80% of tumors. Chronic Hepatitis B Virus (HBV) infection is a major risk factor for hepatocellular carcinoma (HCC), and {beta}-catenin activation is also frequently activated in HBV-associated HCCs. The goal of this research was to determine whether activation of CAR in a mouse model of chronic HBV infection would result in tumor formation and whether these tumors would display increased {beta}-catenin activation. Approach and ResultsWe treated transgenic mice expressing the HBV X protein (HBx) in hepatocytes with a single dose of the potent CAR agonist TCPOBOP. After 10 months, these mice developed large liver tumors that are characterized by {beta}-catenin nuclear localization and upregulation of {beta}-catenin targets. The {beta}-catenin regulator FoxM1 and the oxidative stress master regulator Nrf2, both of which are CAR gene targets, were also overactivated in tumors. The CAR/HBx tumors share a conserved gene signature with HBV-related human hepatocellular carcinoma. ConclusionsActivation of CAR in the presence of HBx results in tumors with strong {beta}-catenin activation. The mouse model we have described reflects the gene expression patterns seen in human HBV-associated HCC and presents an attractive basis for future studies.

cancer biology↗