Biology subjects

Joy, N.

Publications and source records attributed to Joy, N..

3 recordsLinked to original sources

bioRxiv2024

Notch signaling stabilizes lengths of motile cilia in multiciliated cells in the lung

Airway multiciliated cells (MCs) maintain respiratory health by clearing mucus and trapped particles through the beating of motile cilia. While it is known that ciliary lengths decrease along the proximal-distal (P-D) axis of the tracheobronchial tree, how this is regulated is unclear. Here, we demonstrate that canonical Notch signaling in MCs plays a critical role in stabilizing ciliary length. Inhibition of Notch signaling in MCs results in ciliary shortening in the trachea, lengthening in the distal airway, and to region-specific alterations in gene expression. We probe how environmental challenges impact MC homeostasis using germ-free and Mycobacterium tuberculosis (M. tb) infection models. While germ-free conditions do not perturb ciliary lengths, M. tb infection leads to lengthening of distal airway cilia, correlating with a downregulation of Notch signaling. These findings reveal that ciliary length and the P-D gradient in the airways are actively regulated, with Notch signaling serving as a stabilizing mechanism.

cell biology↗

bioRxiv2023

NEUROEPITHELIAL BODIES AND TERMINAL BRONCHIOLES ARE NICHES FOR DISTINCTIVE CLUB CELLS THAT CAN REPAIR AIRWAYS FOLLOWING ACUTE NOTCH INHIBITION

Airway club cells (CCs) have the dual role of a secretory cell and a progenitor cell. Using pharmacological, genetic, and cell-ablation approaches we probe the role of canonical Notch signalling in the regulation of the regenerative capacity of CCs. We report that in response to its perturbation, different subpopulations of CCs adopt distinct fates. Upon acute inhibition of Notch, the majority transdifferentiate into multiciliated cells. However, a "variant" subpopulation (v-CCs), juxtaposed with Neuroepithelial Bodies (5-10%) and neighbouring bronchioalveolar duct junctions (>80%), does not. Instead, v-CCs transition into partially differentiated/lineage ambiguous states but can revert to a CC fate upon restoration of Notch signalling and repopulate the airways with CCs and multiciliated cells. Analysis of a v-CC lineage marker (Uroplakin3a), coupled with sequential Notch inhibition, reveals that differential responses of v-CCs to Notch inhibition are regulated by their cellular microenvironment. We propose that perturbations to Notch signalling may be a common consequence of airway injury and that microenvironmental signals diversify CCs to create a robust pool that can repair airways upon acute Notch inhibition.

cell biology↗

bioRxiv2022

m6A modification of U6 snRNA modulates usage of two major classes of pre-mRNA 5' splice site

Alternative splicing of messenger RNAs is associated with the evolution of developmentally complex eukaryotes. Splicing is mediated by the spliceosome, and docking of the pre-mRNA 5 splice site into the spliceosome active site depends upon pairing with the conserved ACAGA sequence of U6 snRNA. In some species, including humans, the central adenosine of the ACAGA box is modified by N6 methylation, but the role of this m6A modification is poorly understood. Here we show that m6A modified U6 snRNA determines the accuracy and efficiency of splicing. We reveal that the conserved methyltransferase, FIO1, is required for Arabidopsis U6 snRNA m6A modification. Arabidopsis fio1 mutants show disrupted patterns of splicing that can be explained by the sequence composition of 5 splice sites and cooperative roles for U5 and U6 snRNA in splice site selection. U6 snRNA m6A influences 3 splice site usage and reinforces splicing fidelity at elevated temperature. We generalise these findings to reveal two major classes of 5 splice site in diverse eukaryotes, which display anti-correlated interaction potential with U5 snRNA loop 1 and the U6 snRNA ACAGA box. We conclude that U6 snRNA m6A modification contributes to the selection of degenerate 5 splice sites crucial to alternative splicing.

molecular biology↗