Biology subjects

Behera, R.

Publications and source records attributed to Behera, R..

4 recordsLinked to original sources

bioRxiv2025

KIF5B and Dynein regulate adhesion-dependent Golgi organization and microtubule acetylation

Cell-matrix adhesion regulates Golgi organization through Arf1-mediated dynein recruitment, maintaining its juxtanuclear localization. On loss of adhesion, Arf1 activation drops, causing loss of dynein, promoting differential disorganization of cis- vs trans-Golgi along microtubules. Golgi regulates microtubule nucleation and stability. In fibroblasts, acetylated tubulin levels drop on loss of adhesion, recovering on re-adhesion with time. Active Arf1 overexpression in preventing Golgi disorganization sustains microtubule acetylation, also seen in T24 bladder cancer cells. Active Arf1 binds KIF5B, recruiting it to the Golgi. KIF5B and dynein knockdown disorganize the Golgi as ministacks, with cis- and trans-Golgi. Dynein knockdown disrupts MTOC positioning, causing ministacks to disperse, preventing Golgi reorganization upon re-adhesion. Dispersed ministacks interestingly maintain microtubule acetylation in adherent and non-adherent cells. The joint KIF5B-dynein knockdown causes the Golgi to lose its ribbon morphology, becoming compact while keeping cis- and trans-Golgi together. This also causes a change in spreading, aspect ratio and migration of knockdown cells, which could be regulated by their Golgi phenotype. In evaluating adhesion-dependent Golgi organization, we reveal the Arf1-KIF5B-dynein crosstalk to regulate Golgi-dependent tubulin acetylation and cell function. SummaryKIF5B and dynein are vital microtubule-associated motors that drive organelle positioning and organization. Adhesion-dependent Arf1 activation mediates KIF5B and dyneins recruitment to the Golgi, regulating its organization and position. This, in turn, regulates microtubule acetylation levels, localization, and cellular functions.

cell biology↗

bioRxiv2024

Altered AP-1, RUNX, and EGR chromatin dynamics drive fibrotic lung disease

Pulmonary fibrosis, including systemic sclerosis-associated interstitial lung disease (SSc-ILD), involves myofibroblasts and SPP1hi macrophages as drivers of fibrosis. Single-cell RNA sequencing has delineated fibroblast and macrophages transcriptomes, but limited insight into transcriptional control of profibrotic gene programs. To address this challenge, we analyzed multiomic snATAC/snRNA-seq on explanted SSc-ILD and donor control lungs. The neural network tool ChromBPNet inferred increased TF binding at single base pair resolution to profibrotic genes, including CTHRC1 and ADAM12, in fibroblasts and SPP1 and CCL18 in macrophages. The novel algorithm HALO confirmed AP-1, RUNX, and EGR TF activity controlling profibrotic gene programs and established TF-regulatory element-gene networks. This TF action atlas provides comprehensive insights into the transcriptional regulation of fibroblasts and macrophages in healthy and fibrotic human lungs.

systems biology↗

bioRxiv2022

Toxoplasma gondii Coq1 is a heptaprenyl diphosphate synthase and its inhibition by a lipophilic bisphosphonate protects mice against T. gondii infection

Prenyldiphosphate synthases catalyze the reaction of allylic diphosphates with one or more isopentenyl diphosphate molecules to form compounds such as farnesyl diphosphate, used in e.g. sterol biosynthesis and protein prenylation, as well as longer "polyprenyl" diphosphates, used in ubiquinone and menaquinone biosynthesis. Quinones play an essential role in electron transport and are associated with the inner mitochondrial membrane due to the presence of the polyprenyl group. In this work, we investigated the synthesis of the polyprenyl diphosphate that alkylates the ubiquinone ring precursor in Toxoplasma gondii, an opportunistic pathogen that causes serious disease in immunocompromised patients and the unborn fetus. The enzyme that catalyzes this early step of the ubiquinone synthesis is Coq1 (TgCoq1), and we show that it produces the C35 species, heptaprenyl diphosphate. TgCoq1 localizes to the mitochondrion, and is essential for in vitro T. gondii growth. We demonstrate that the growth defect of a T. gondii TgCoq1 mutant is rescued by complementation with a homologous TgCoq1 gene or with a (C45) solanesyl diphosphate synthase from Trypanosoma cruzi (TcSPPS). We find that a lipophilic bisphosphonate (BPH-1218) inhibits T. gondii growth at low nM concentrations, while overexpression of the TgCoq1 enzyme dramatically reduced growth inhibition by the bisphosphonate. Both the severe growth defect of the mutant and the inhibition by BPH-1218 were rescued by supplementation with a long chain (C30) ubiquinone (UQ6). Importantly, BPH-1218 also protected mice against a lethal T. gondii infection. TgCoq1 thus represents a potential drug target that could be exploited for improved chemotherapy of toxoplasmosis. ImportanceMillions of people are infected with Toxoplasma gondii and the available treatment for toxoplasmosis is not ideal. Most of the drugs currently used are only effective for the acute infection and treatment can trigger serious side-effects requiring changes in the therapeutic approach. There is, therefore, a compelling need for safe and effective treatments for toxoplasmosis. In this work, we characterize an enzyme of the mitochondrion of T. gondii that can be inhibited by an isoprenoid pathway inhibitor. We present evidence that demonstrate that inhibition of the enzyme is linked to parasite death. In addition, the drug is able to protect mice against a lethal dose of T. gondii. Our results thus reveal a promising chemotherapeutic target for the development of new medicines for toxoplasmosis.

microbiology↗

bioRxiv2021

Myofibroblast transcriptome indicates SFRP2+ fibroblast progenitors in systemic sclerosis skin

Skin and lung fibrosis in systemic sclerosis (SSc) is driven by myofibroblasts, alpha-smooth muscle actin expressing cells that arise from a variety of cell types in murine fibrosis models. Utilizing single cell RNA-sequencing to examine the transcriptome changes, we show that SSc dermal myofibroblasts arise from an SFRP2/DPP4-expressing progenitor fibroblast population that globally upregulates expression of transcriptome markers, such as PRSS23 and THBS1. Only a fraction of SSc fibroblasts differentiate into myofibroblasts, as shown by expression of additional markers, SFRP4 and FNDC1. The myofibroblast transcriptome implicates upstream transcription factors that drive myofibroblast differentiation.

cell biology↗