Biology subjects

Yang, J. H.

Publications and source records attributed to Yang, J. H..

6 recordsLinked to original sources

bioRxiv2024

In vitro spatiotemporal reconstruction of human skeletal muscle organogenesis

Spatiotemporal recapitulation of long-range trajectories for lineages that influence body patterning along the medio-lateral and proximal-distal axes during embryogenesis in an in vitro system remains elusive. Here we introduce a three-dimensional organoid approach, termed Gastruloids-Lateraloid-Musculoids (GLMs), to model human neural crest, lateral plate mesoderm and skeletal muscle lineage development at the forelimb level following gastrulation and during limb patterning. GLMs harvest neuro-mesodermal progenitors with the potential to establish neural and paraxial mesodermal populations, while single cell analyses and spatial transcriptomics demonstrate promotion of mesodermal lineage segregation during gastrulation and spatial recapitulation of migration events along the medio-lateral axis for vagal neural crest, hypaxial myogenesis and lateral plate mesodermal lineages. Comparative analyses to developmental atlases and adult muscle stem cell data confirm a pool of hypaxial migrating myogenic progenitors that in a niche dependent manner change their embryonic anatomical developmental program to a fetal myogenic program, thus enabling them to resist specification in a cell autonomous manner and facilitate long term in vitro expansion. GLMs model human myogenesis at the forelimb level, establish fetal muscle stem cells equivalent to those that sustain the growth phase of the embryo and provide a 3D in vitro system for investigating neural crest, early fore-gut and lateral plate mesoderm development.

developmental biology↗

bioRxiv2024

34-parameter full spectrum immunophenotyping panel of human regulatory and effector lymphocytes

This 34-marker sentinel, intracellular, full-spectrum flow cytometry panel profiles regulatory and effector T, B and NK lymphocytes in human cryopreserved peripheral blood mononuclear cells. The panel focuses on cell trafficking, activation, exhaustion and proliferation, and permits easy customisation in two positions to accommodate other targets of the users interest. By combining breadth and depth of phenotyping, this panel is designed to maximise the information obtained from limited cell material and therefore will be particularly useful in mechanistic studies of immunomodulatory drugs for autoimmune disease, cancer and transplantation, where multiple immune populations may be affected.

immunology↗

bioRxiv2023

KatG catalase deficiency confers bedaquiline hyper-susceptibility to isoniazid resistant Mycobacterium tuberculosis

Multidrug-resistant tuberculosis (MDR-TB) is a growing source of global mortality and threatens global control of tuberculosis (TB) disease. The diarylquinoline bedaquiline (BDQ) recently emerged as a highly efficacious drug against MDR-TB, defined as resistance to the first-line drugs isoniazid (INH) and rifampin. INH resistance is primarily caused by loss-of-function mutations in the catalase KatG, but mechanisms underlying BDQs efficacy against MDR-TB remain unknown. Here we employ a systems biology approach to investigate BDQ hyper-susceptibility in INH-resistant Mycobacterium tuberculosis. We found hyper-susceptibility to BDQ in INH-resistant cells is due to several physiological changes induced by KatG deficiency, including increased susceptibility to reactive oxygen species and DNA damage, remodeling of transcriptional programs, and metabolic repression of folate biosynthesis. We demonstrate BDQ hyper-susceptibility is common in INH-resistant clinical isolates. Collectively, these results highlight how altered bacterial physiology can impact drug efficacy in drug-resistant bacteria.

microbiology↗

bioRxiv2023

YlaN is an iron(II) binding protein that functions to relieve Fur-mediated repression of gene expression in Staphylococcus aureus

Iron (Fe) is a trace nutrient required by nearly all organisms. As a result of the demand for Fe and the toxicity of non-chelated cytosolic ionic Fe, regulatory systems have evolved to tightly balance Fe acquisition and usage while limiting overload. In most bacteria, including the mammalian pathogen Staphylococcus aureus, the ferric uptake regulator (Fur) is the primary transcriptional regulator that controls the transcription of genes that code for Fe uptake and utilization proteins. YlaN was demonstrated to be essential in Bacillus subtilis unless excess Fe is added to the growth medium, suggesting a role in Fe homeostasis. Here, we demonstrate that YlaN is expendable in S. aureus; however, YlaN became essential upon Fe deprivation. A null fur allele bypassed the essentiality of YlaN. The transcriptional response of Fur derepression resulted in a reprogramming of metabolism to prioritize fermentative growth over respiratory growth. The absence of YlaN diminished the derepression of Fur-dependent transcription during Fe limitation. Bioinformatic analyses suggest that ylaN was recruited to Gram positive bacteria and once acquired was maintained in the genome as it co-evolved with Fur. Consistent with a role for YlaN in influencing Fur-dependent regulation, YlaN and Fur interacted in vivo. YlaN bound Fe(II) in vitro using oxygen or nitrogen ligands with an association constant that is consistent with a physiological role in Fe sensing and/or buffering. These findings have led to a model wherein YlaN is an Fe(II) binding protein that influences Fur-dependent regulation through direct interaction. ImportanceIron (Fe) is an essential nutrient for nearly all organisms. If Fe homeostasis is not maintained, Fe can accumulate in the cytosol where it is toxic. Questions remain about how cells efficiently balance Fe uptake and usage to prevent imbalance. Iron uptake and proper metalation of proteins are essential processes in the mammalian bacterial pathogen Staphylococcus aureus. Understanding the gene products involved in Fe ion regulation, uptake, and usage, as well as the physiological adaptations that S. aureus uses to survive in Fe-depleted conditions, will provide insight into the role that Fe has in pathogenesis. These data will also provide insight into the selective pressures imparted by the mammalian host.

microbiology↗

bioRxiv2022

A comprehensive update to the Mycobacterium tuberculosis H37Rv reference genome

H37Rv is the most widely used M. tuberculosis strain. Its genome is globally used as the M. tuberculosis reference sequence. We developed Bact-Builder, a pipeline that leverages consensus building to generate complete and highly accurate gap-closed bacterial genomes and applied it to three independently sequenced cultures of a parental H37Rv laboratory stock. Two of the 4,417,942 base-pair long H37Rv assemblies were 100% identical, with the third differing by a single nucleotide. Compared to the existing H37Rv reference, the new sequence contained approximately 6.4 kb additional base pairs encoding ten new regions. These regions included insertions in PE/PPE genes and new paralogs of esxN and esxJ, which were differentially expressed compared to the reference genes. Additional sequencing and assembly with Bact-Builder confirmed that all 10 regions were also present in widely accepted strains of H37Rv: NR123 and TMC102. Bact-builder shows promise as an improved method to perform extremely accurate and reproducible de novo assemblies of bacterial genomes. Furthermore, our findings provide important updates to the primary tuberculosis reference genome.

microbiology↗

bioRxiv2021

DNA double-strand break end synapsis by DNA loop extrusion

DNA double-strand breaks (DSBs) occur every cell cycle and must be efficiently repaired. Non-homologous end joining (NHEJ) is the dominant pathway for DSB repair in G1-phase. The first step of NHEJ is to bring the two DSB ends back into proximity (synapsis). However, although synapsis is generally assumed to occur through passive diffusion, we show here that passive diffusion is unlikely to be consistent with the speed and efficiency of NHEJ observed in cells. Instead, we hypothesize that DNA loop extrusion facilitates synapsis. By combining experimentally constrained simulations and theory, we show that the simplest loop extrusion model only modestly facilitates synapsis. Instead, a loop extrusion model with targeted loading of loop extruding factors (LEFs), a small portion of long-lived LEFs as well as LEF stabilization by boundary elements and DSB ends achieves fast synapsis with near 100% efficiency. We propose that loop extrusion plays an underappreciated role in DSB repair.

biophysics↗