Biology subjects

Weis, M.

Publications and source records attributed to Weis, M..

6 recordsLinked to original sources

bioRxiv2025

Proteome profiling of plant Cajal bodies uncovers kingdom-specific components

Insight into the molecular composition of cellular microenvironments is essential for understanding their function. Membraneless organelles (MLO), such as the nuclear Cajal body (CB), play fundamental roles in eukaryotic cells, but their very nature poses a challenge to biochemical isolation. Despite the relevance of the CB for cell function in plants and animals, its proteome remains to be profiled. Here, we purify plant CBs using a combination of biochemical isolation and fluorescence-activated particle sorting (FAPS) and define their proteome by mass spectrometry. Our work identifies 15 and 95 proteins uniquely localized and enriched in CBs, respectively, of which 22 are also labelled by CB markers in proximity labelling assays. CB proteins are preferentially involved in RNA processing, chromatin organization, and gene expression. While a partial overlap with known animal CB proteins exists, our data reveal a distinct, kingdom-specific CB proteome. These results provide the first comprehensive proteome of CBs and establishes a foundation for dissecting the molecular functions of this organelle across multicellular lineages.

plant biology↗

bioRxiv2023

Catalytic antibodies in arrhythmogenic cardiomyopathy patients cleave desmoglein 2 and N-cadherin and impair cardiomyocyte cohesion

AimsArrhythmogenic cardiomyopathy (AC) is a severe heart disease predisposing to ventricular arrhythmias and sudden cardiac death caused by mutations affecting intercalated disc (ICD) proteins and aggravated by physical exercise. Recently, autoantibodies targeting ICD proteins, including the desmosomal cadherin desmoglein 2 (DSG2), were reported in AC patients and were considered relevant for disease development and progression, particularly in patients without underlying pathogenic mutations. However, it is unclear at present whether these autoantibodies are pathogenic and by which mechanisms show specificity for DSG2 and thus can be used as a diagnostic tool. Methods and ResultsIgG fractions were purified from 15 AC patients and 4 healthy controls. Immunostainings dissociation assays, atomic force microscopy (AFM), western blot analysis and Triton-X-100 assays were performed utilizing human heart left ventricle tissue, HL-1 cells, and murine cardiac slices. Immunostainings revealed that autoantibodies against ICD proteins are prevalent in AC and most autoantibody fractions have catalytic properties and cleave the ICD adhesion molecules DSG2 and N-cadherin, thereby reducing cadherin interactions as revealed by AFM. Furthermore, most of the AC-IgG fractions causing loss of cardiomyocyte cohesion activated p38MAPK, which is known to contribute to a loss of desmosomal adhesion in different cell types, including cardiomyocytes. In addition, p38MAPK inhibition rescued the loss of cardiomyocyte cohesion induced by AC-IgGs. ConclusionOur study demonstrates that catalytic autoantibodies play a pathogenic role by cleaving ICD cadherins and thereby reducing cardiomyocyte cohesion by a mechanism involving p38MAPK activation. Finally, we conclude that DSG2 cleavage by autoantibodies could be used as a diagnostic tool for AC.

cell biology↗

bioRxiv2021

XBP1s-Mediated Endoplasmic Reticulum Proteostasis Network Enhancement Can Selectively Improve Folding and Secretion of an Osteogenesis Imperfecta-Causing Collagen-I Variant

Osteogenesis imperfecta (OI) is typically caused by autosomal dominant mutations in genes encoding collagen type-I, most commonly resulting in Gly[->]Ser triple-helical domain substitutions that disrupt collagen folding and/or stability. Here, we test the hypothesis that upregulating the endoplasmic reticulum (ER) proteo-stasis network via the unfolded protein response (UPR) can improve the folding and secretion of the clinically severe, prototypical OI-causing COL1A1 p.G425S collagen-1(I) variant. We first show that small molecules that activate the entire UPR by causing global ER protein misfolding stress severely ablate collagen-I secretion from both G425S Col1(I)- and wild-type (WT) Col1(I)-expressing primary fibroblasts. In contrast, stress-independent, specific induction of just the UPRs XBP1s transcriptional response can enhance collagen-I secretion from G425S Col1(I) patient primary fibroblasts up to ~300% of basal levels. Notably, the effect is selective - collagen-I secretion from WT Col1(I)-expressing healthy donor primary fibroblasts is unaltered by XBP1s. XBP1s pathway activation appears to post-translationally enhance the folding/assembly and secretion of G425S Col1(I), as only modest impacts on collagen-I transcription or synthesis are observed. Consistent with this notion, we find that the stable, triple-helical collagen-I secreted by XBP1s-activated G425S 1(I) patient fibroblasts includes a higher proportion of the mutant 1(I) polypeptide than the collagen-I secreted under basal ER proteostasis conditions. We note that consistent reproducibility of these results is dependent on as yet unascertained experimental variables. Still, these promising observations suggest the potential for ER proteo-stasis network modulation to improve mutant collagen proteostasis in the collagenopathies, motivating further investigation of the effects generality, underlying mechanism, and potential therapeutic benefits.

cell biology↗

bioRxiv2021

Age-Related Type I Collagen Modifications Reveal Tissue-Defining Differences Between Ligament and Tendon

Tendons and ligaments tend to be pooled into a single category as dense elastic bands of collagenous connective tissue. They do have many similar properties, for example both tissues are flexible cords of fibrous tissue that join bone to either muscle or bone. Tendons and ligaments are both prone to degenerate and rupture with only limited capacity to heal, however; healing outcomes for tendons are often faster than ligament injuries. Type I collagen constitutes about 80% of the dry weight of tendons and ligaments and is principally responsible for the core strength of each tissue. Collagen synthesis is a complex process with multiple steps and numerous post-translational modifications including proline and lysine hydroxylation, hydroxylysine glycosylation and covalent cross-linking. The chemistry, placement and quantity of intramolecular and intermolecular cross-links are believed to be key contributors to the tissue-specific variations in material strength and biological properties of collagens. As tendons and ligaments grow and develop, the collagen cross-links are known to chemically mature, strengthen and change in profile. Accordingly, changes in cross-linking and other post-translational modifications are likely associated with tissue development and degeneration. Using mass spectrometry, we have compared tendon and ligaments from fetal and adult bovine knee joints to investigate changes in collagen post-translational properties. Although hydroxylation levels at the type I collagen helical cross-linking lysine residues were similar in all adult tissues, ligaments had significantly higher levels of glycosylation at these sites compared to tendon. Differences in lysine hydroxylation were also found between the tissues at the telopeptide cross-linking sites. Total collagen cross-linking analysis, including mature trivalent cross-links and immature divalent cross-links, revealed unique cross-linking profiles between tendon and ligament tissues. Tendons were found to have a significantly higher frequency of smaller diameter collagen fibrils compared with ligament, which we propose is a consequence of the unique cross-linking profile of each tissue. Understanding the specific molecular characteristics that define and distinguish these specialized tissues will be important for designing improved orthopedic treatment approaches.

biochemistry↗

bioRxiv2019

Spatial simulation of co-designed land-cover change scenarios in New England: Alternative futures and their consequences for conservation priorities

To help prepare for an uncertain future, planners and scientists often engage with stakeholders to co-design alternative scenarios of land-use change. Methods to translate the resulting qualitative scenarios into quantitative simulations that characterize the future landscape condition are needed to understand consequences of the scenarios while maintaining the legitimacy of the process. We use the New England Landscape Futures (NELF) project as a case study to demonstrate a transparent method for translating participatory scenarios to simulations of Land-Use and Land-Cover (LULC) change and for understanding the major drivers of land-use change and diversity of plausible scenarios and the consequences of alternative land-use pathways for conservation priorities. The NELF project co-designed four narrative scenarios that contrast with a Recent Trends scenario that projects a continuation of observed changes across the 18-million-hectare region during the past 20 years. Here, we (1) describe the process and utility of translating qualitative scenarios into spatial simulations using a dynamic cellular land change model; (2) evaluate the outcomes of the scenarios in terms of the differences in the LULC configuration relative to the Recent Trends scenario and to each other; (3) compare the fate of forests within key areas of concern to the stakeholders; and (4) describe how a user-inspired outreach tool was developed to make the simulations and analyses accessible to diverse users. The four alternative scenarios populate a quadrant of future conditions that crosses high to low natural resource planning and innovation with local to global socio-economic connectedness. The associated simulations are strongly divergent in terms of the amount of LULC change and the spatial pattern of change. Features of the simulations can be linked back to the original storylines. Among the scenarios there is a fivefold difference in the amount of high-density development, and a twofold difference in the amount of protected land. Overall, the rate of LULC change has a greater influence on forestlands of concern to the stakeholders than does the spatial configuration. The simulated scenarios have been integrated into an online mapping tool that was designed via a user-engagement process to meet the needs of diverse stakeholders who are interested the future of the land and in using future scenarios to guide land use planning and conservation priorities.

ecology↗

bioRxiv2018

Zebrafish type I collagen mutants faithfully recapitulate human type I collagenopathies

The type I collagenopathies are a group of heterogeneous connective tissue disorders, that are caused by mutations in the genes encoding type I collagen and include specific forms of Osteogenesis Imperfecta (OI) and the Ehlers-Danlos syndrome (EDS). These disorders present with a broad disease spectrum and large clinical variability of which the underlying genetic basis is still poorly understood. In this study, we systematically analyzed skeletal phenotypes in a large set of zebrafish, with diverse mutations in the genes encoding type I collagen, representing different genetic forms of human OI, and the first zebrafish model of human EDS, which harbors characteristic defects in the soft connective tissues. Furthermore, we provide insight into how zebrafish and human type I collagen are compositionally and functionally related, which is relevant in the interpretation of human type I collagen related disease models. Our studies reveal a high degree of inter-genotype variability in phenotypic expressivity that closely correlates with associated OI severity. Further, we demonstrate the potential for select mutations to give rise to variable phenotypic penetrance, mirroring the clinical variability associated with human disease pathology. Therefore, our work suggests the potential for zebrafish to aid in identifying unknown genetic modifiers and mechanisms underlying the phenotypic variability in OI and related disorders. This will improve diagnostic strategies and enable the discovery of new targetable pathways for pharmacological intervention\n\nSIGNIFICANCE STATEMENTType I collagenopathies are a heterogenous group of connective tissue disorders, caused by genetic defects in type I collagen. Inherent to these disorders is a large clinical variability, of which the underlying molecular basis remains undefined. By systematically analyzing skeletal phenotypes in a large set of type I collagen zebrafish mutants we show that zebrafish models are able to both genocopy and phenocopy different forms of human type I collagenopathies, arguing for a similar pathogenetic basis. This study illustrates the potential of zebrafish as a tool to further dissect the molecular basis of phenotypic variability in human type I collagenopathies to improve diagnostic strategies as well as promote the discovery of new targetable pathways for pharmacological intervention of these disorders.

genetics↗