Biology subjects

Huebner, R.

Publications and source records attributed to Huebner, R..

6 recordsLinked to original sources

bioRxiv2021

Cell adhesions link subcellular actomyosin dynamics to tissue scale force production during vertebrate convergent extension.

Axis extension is a fundamental biological process that shapes multicellular organisms. The design of an animals body plan is encoded in the genome and execution of this program is a multiscale mechanical progression involving the coordinated movement of proteins, cells, and whole tissues. Thus, a key challenge to understanding axis extension is connecting events that occur across these various length scales. Here, we use approaches from proteomics, cell biology, and tissue biomechanics to describe how a poorly characterized cell adhesion effector, the Armadillo Repeat protein deleted in Velo-Cardio-Facial syndrome (Arvcf) catenin, controls vertebrate head-to-tail axis extension. We find that Arvcf catenin is required for axis extension within the intact organism but is not required for extension of isolated tissues. We then show that the organism scale phenotype is caused by a modest defect in force production at the tissue scale that becomes apparent when the tissue is challenged by external resistance. Finally, we show that the tissue scale force defect results from dampening of the pulsatile recruitment of cell adhesion and cytoskeletal proteins to cell membranes. These results not only provide a comprehensive understanding of Arvcf function during an essential biological process, but also provide insight into how a modest cellular scale defect in cell adhesion results in an organism scale failure of development.

developmental biology↗

bioRxiv2021

Convergent extension requires adhesion-dependent biomechanical integration of cell crawling and junction contraction

Convergent extension is an evolutionarily conserved collective cell movement that elongates the body axis of almost all animals and is required for the morphogenesis of several organ systems. Decades of study have revealed two distinct mechanisms of cell movement during CE, one based on cell crawling and the other on junction contraction. How these two behaviors collaborate during CE is not understood. Here, using quantitative live cell imaging we show that these two modes act both independently and in concert during CE, but that cell movement is more effective when the two modes are integrated via mechano-reciprocity. Based on these findings, we developed a novel computational model that for the first time treats crawling and contraction independently. This model not only confirmed the biomechanical efficacy of integrating the two modes, but also revealed for the first time how the two modes -and their integration- are influenced by cell adhesion. Finally, we use these new insights to further understand the complex CE phenotype resulting from loss of the C-cadherin interacting catenin Arvcf. These data are significant for providing new biomechanical and cell biological insights into a fundamental morphogenetic process that is implicated in human neural tube defects and skeletal dysplasias.

developmental biology↗

bioRxiv2020

Characterization of genetic diversity and population structure within Staphylococcus chromogenes by multilocus sequence Typing

Staphylococcus chromogenes is a common skin commensal in cattle and has been identified as a frequent cause of bovine mastitis and intramammary infections. To better understand the extent of strain diversity within this species and to facilitate study of strain variation as a factor in pathogenicity, we have developed a seven locus Multilocus Sequence Typing (MLST) scheme. The scheme was tested on 120 isolates collected from three geographic locations, Vermont and Washington State in the United States and Belgium. A total of 46 sequence types (STs) were identified with most of the STs being location specific. The utility of the typing scheme is indicated by a discrimination power of 95.6% for all isolates and greater than 90% for isolates from each of the three locations. Phylogenetic analysis placed 39 of the 46 STs into single core group consistent with a common genetic lineage; the STs in this group differ by less than 0.5% at the nucleotide sequence level. Most of the diversification in this lineage group can be attributed to mutation; recombination plays a limited role. This lineage group includes two clusters of single nucleotide variants in starburst configurations indicative of recent clonal expansion; nearly 50% of the isolates sampled in this study are in these two clusters. The remaining seven STs were set apart from the core group by having alleles with highly variable sequences at one or more loci. Recombination had a higher impact than mutation in the diversification of these outlier STs. Alleles with hypervariable sequences were detected at five of the seven loci used in the MLST scheme; the average sequence distances between the hypervariable alleles and the common core alleles ranged from 12 to 34 nucleotides. The extent of these sequence differences suggests the hypervariable alleles may be remnants of an ancestral genotype.

microbiology↗

bioRxiv2020

A temporally resolved transcriptome for developing Keller explants of the Xenopus laevis dorsal marginal zone

Explanted tissues from vertebrate embryos reliably develop in culture and have provided essential paradigms for understanding embryogenesis, from early embryological investigations of induction, to the extensive study of Xenopus animal caps, to the current studies of mammalian gastruloids. Cultured explants of the Xenopus dorsal marginal zone ("Keller" explants) serve as a central paradigm for studies of convergent extension cell movements, yet we know little about the global patterns of gene expression in these explants. In an effort to more thoroughly develop this important model system, we provide here a time-resolved bulk transcriptome for developing Keller explants.

developmental biology↗

bioRxiv2020

Cadherin clustering controls heterogeneous, asymmetric junction dynamics during vertebrate axis elongation

Morphogenesis is governed by the interplay of molecular signals and mechanical forces across multiple length scales. The last decade has seen tremendous advances in our understanding of the dynamics of protein localization and turnover at sub-cellular length scales, and at the other end of the spectrum, of mechanics at tissue-level length scales. Integrating the two remains a challenge, however, because we lack a detailed understanding of the subcellular patterns of mechanical properties of cells within tissues. Here, in the context of the elongating body axis of a vertebrate embryo, we combine tools from cell biology and physics to demonstrate that individual cell-cell junctions display finely-patterned local mechanical heterogeneity along their length. We show that such local mechanical patterning is essential for the cell movements of convergent extension and is imparted by locally patterned clustering of a classical cadherin. Finally, the patterning of cadherins and thus local mechanics along cell-cell junctions are controlled by Planar Cell Polarity signaling, a key genetic module for CE that is mutated in diverse human birth defects.

cell biology↗

bioRxiv2018

Drug susceptibility testing and mortality in patients treated for tuberculosis in high-burden countries

BackgroundDrug resistance and HIV co-infection are challenges for the global control of tuberculosis.\n\nMethodsWe collected Mycobacterium tuberculosis isolates from adult patients in Cote dIvoire, Democratic Republic of the Congo, Kenya, Nigeria, South Africa, Peru, and Thailand, stratified by HIV status and tuberculosis drug resistance. Molecular or phenotypic drug susceptibility testing (DST) was done locally and at the Swiss tuberculosis reference laboratory. We examined mortality during treatment according to DST results and treatment adequacy in logistic regression models adjusting for sex, age, sputum microscopy and HIV status.\n\nFindings634 tuberculosis patients were included; median age was 33.2 years, 239 (37.7%) were female, 272 (42.9%) HIV-positive and 69 (10.9%) patients died. Based on the reference laboratory DST, 394 (62.2%) strains were pan-susceptible, 45 (7.1%) mono-resistant, 163 (25.7%) multidrug-resistant (MDR-TB), and 30 (4.7%) had pre-extensive or extensive drug resistance (pre-XDR/XDR-TB). Results of reference and local laboratories were discordant in 121 (19.1%) cases, corresponding to a sensitivity of 84.3% and a specificity of 90.8%. In patients with drug-resistant tuberculosis, discordant results were associated with increased mortality (risk ratio 1.81; 95% CI 1.07-3.07). In logistic regression, compared to adequately treated patients with pan-susceptible strains, the adjusted odds ratio for death was 4.23 (95% CI 2.16-8.29) for adequately treated patients with drug-resistant strains and 21.54 (95% CI 3.36-138.1) for inadequately treated patients with drug-resistant strains. HIV status was not associated with mortality.\n\nInterpretationUsing a reference laboratory standard, inaccurate DST leading to inappropriate treatment of drug-resistant tuberculosis, but not HIV infection, contributed to mortality.

epidemiology↗