Biology subjects

Chawla, B.

Publications and source records attributed to Chawla, B..

3 recordsLinked to original sources

bioRxiv2025

Condensin IDC has a Functional ATPase That is Required for X-Chromosome Dosage Compensation in C. elegans

Dosage compensation (DC) in C. elegans utilizes a condensin complex that resembles mitotic condensins, but differs by one subunit, DPY-27. DPY-27 replaces SMC-4, one of the Structural Maintenance of Chromosome (SMC) proteins that is responsible for hydrolyzing ATP, required for condensation of DNA and other mitotic condensin functions. To understand if the ATPase function is required in DC, we first demonstrated that DPY-27 is capable of hydrolyzing ATP in vitro. Then, we used CRISPR/Cas9-mediated genome editing to generate an ATPase mutation in dpy-27 and demonstrated that this mutation results in a loss of DC. Specifically, we found that without ATPase function, DPY-27 containing condensin IDC has reduced capacity to bind DNA, condense the X chromosomes, and facilitate H4K20me1 enrichment on the X-chromosomes. Our results suggest that condensin IDC, like mitotic condensins, uses ATP hydrolysis to perform its functions, making C. elegans DC a model for how activities attributed to mitotic condensins can be used to regulate gene expression.

genetics↗

bioRxiv2023

Strong immunogenicity & protection in mice with PlaCCine: A COVID-19 DNA vaccine formulated with a functional polymer

DNA- based vaccines have demonstrated the potential as a safe and effective modality. PlaCCine, a DNA-based vaccine approach described subsequently relies on a synthetic DNA delivery system and is independent of virus or device. The synthetic functionalized polymer combined with DNA demonstrated stability over 12 months at 4C and for one month at 25C. Transfection efficiency compared to naked DNA increased by 5-15-fold in murine skeletal muscle. Studies of DNA vaccines expressing spike proteins from variants D614G (pVAC15), Delta (pVAC16), or a D614G + Delta combination (pVAC17) were conducted. Mice immunized intramuscular injection (IM) with pVAC15, pVAC16 or pVAC17 formulated with functionalized polymer and adjuvant resulted in induction of spike-specific humoral and cellular responses. Antibody responses were observed after one immunization. And endpoint IgG titers increased to greater than 1x 105 two weeks after the second injection. Neutralizing antibodies as determined by a pseudovirus competition assay were observed following vaccination with pVAC15, pVAC16 or pVAC17. Spike specific T cell immune responses were also observed following vaccination and flow cytometry analysis demonstrated the cellular immune responses included both CD4 and CD8 spike specific T cells. The immune responses in vaccinated mice were maintained for up to 14 months after vaccination. In an immunization and challenge study of K18 hACE2 transgenic mice pVAC15, pVAC16 and pVAC17 induced immune responses lead to decreased lung viral loads by greater than 90% along with improved clinical score. These findings suggest that PlaCCine DNA vaccines are effective and stable and further development against emerging SARS-CoV-2 variants is warranted.

immunology↗

bioRxiv2021

Dual Roles for Nuclear RNAi Argonautes in C. elegans Dosage Compensation

Dosage compensation involves chromosome-wide gene regulatory mechanisms which impact higher order chromatin structure and are crucial for organismal health. Using a genetic approach, we identified Argonaute genes which promote dosage compensation in C. elegans. Dosage compensation in C. elegans hermaphrodites is initiated by the silencing of xol-1 and subsequent activation of the Dosage Compensation Complex (DCC) which binds to both hermaphrodite X chromosomes and reduces transcriptional output by twofold. A hallmark phenotype of dosage compensation mutants is decondensation of the X chromosomes. We characterized this phenotype in Argonaute mutants using X chromosome paint probe and fluorescence microscopy. We found that while nuclear Argonaute mutants hrde-1 and nrde-3 exhibit de-repression of xol-1 transcripts, they also effect X chromosome condensation in a xol-1-independent manner. We also characterized the physiological contribution of Argonaute genes to dosage compensation using genetic assays and find that hrde-1 and nrde-3, together with the piRNA Argonaute prg-1, contribute to healthy dosage compensation both upstream and downstream of xol-1.

genetics↗