Biology subjects

Lingamallu, S. M.

Publications and source records attributed to Lingamallu, S. M..

4 recordsLinked to original sources

bioRxiv2025

Notch and Wnt signalling interact for proper prosensory and non-sensory domain formation

The prosensory domain (PSD) of the developing inner ear develops into the sensory hair cells, supporting cells, and neurons necessary for hearing and balance. Although Notch-Jag1 signalling is known to maintain Sox2 expression in this domain, the mechanisms by which Notch sustains prosensory identity have remained unclear. Here, we show that this function does not require canonical RBPJ{kappa}-dependent transcription. Using chick in ovo electroporation, Notch reporter assays, and conditional mouse mutants, we find that canonical Notch signalling is active during neurogenesis but not within the Sox2-positive PSD. Jag1 loss leads to a gradual loss of Sox2, yet RBPJ{kappa} mutants retain Sox2, indicating a non- canonical Notch pathway. We further reveal that the non-sensory determinant Lmx1a is regulated by Wnt/{beta}-catenin signalling and that manipulating Wnt activity shifts the balance between Lmx1a and Sox2 expression. Finally, we show that NICD can directly interact with {beta}-catenin in the cytoplasm, suggesting that NICD sequesters {beta}-catenin to suppress Wnt activity and stabilise Sox2 in the PSD. Collectively, these findings support a model where prosensory maintenance occurs through non-canonical Notch signalling acting together with Wnt, forming a combined WNTCH regulatory module that coordinates sensory and non-sensory fate specification.

developmental biology↗

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↗

bioRxiv2020

Niclosamide inhibits SARS-CoV2 entry by blocking internalization through pH-dependent CLIC/GEEC endocytic pathway

Many viruses utilize the host endo-lysosomal network to infect cells. Tracing the endocytic itinerary of SARS-CoV2 can provide insights into viral trafficking and aid in designing new therapeutic targets. Here, we demonstrate that the receptor binding domain (RBD) of SARS-CoV2 is internalized via the clathrin and dynamin-independent, pH-dependent CLIC/GEEC (CG) endocytic pathway. Endosomal acidification inhibitors like BafilomycinA1 and NH4Cl, which inhibit the CG pathway, strongly block the uptake of RBD. Using transduction assays with SARS-CoV2 Spike-pseudovirus, we confirmed that these acidification inhibitors also impede viral infection. By contrast, Chloroquine neither affects RBD uptake nor extensively alters the endosomal pH, yet attenuates Spike-pseudovirus entry, indicating a pH-independent mechanism of intervention. We screened a subset of FDA-approved acidification inhibitors and found Niclosamide to be a potential SARS-CoV2 entry inhibitor. Niclosamide, thus, could provide broader applicability in subverting infection of similar category viruses entering host cells via this pH-dependent endocytic pathway.

cell biology↗