Biology subjects

Brody, S.

Publications and source records attributed to Brody, S..

4 recordsLinked to original sources

bioRxiv2025

Molecular organization of the distal tip of vertebrate motile cilia

The beating of cilia on multi-ciliated cells (MCCs) is essential for normal development and homeostasis in animals. But while the structure and function of basal bodies and axonemes have received significant attention recently, the distal tips of MCC cilia remain relatively poorly defined. Here, we characterize the molecular organization of the distal tip of vertebrate MCC cilia, characterizing two distinct domains occupied by distinct protein constituents. Using frog, mouse, and human MCCs, we find that two largely uncharacterized proteins, Ccdc78 and Ccdc33 occupy a previously undefined region at the extreme distal tip, and these are required for the normal organization of all other known tip proteins. Ccdc78 and Ccdc33 each display robust microtubule-bundling activity both in vivo and in vitro, yet each is independently required for normal length regulation of MCC cilia. Moreover, loss of each protein elicits a distinct pattern of defective cilia beating and resultant fluid flow. Thus, two previously undefined proteins form a key module essential for organizing and stabilizing the distal tip of motile cilia in vertebrate MCCs. We propose that these ill-defined proteins represent potential disease loci for motile ciliopathies.

cell biology↗

bioRxiv2023

Genetic transformation of the frog-killing chytrid fungus Batrachochytrium dendrobatidis

Batrachochytrium dendrobatidis (Bd), a causative agent of chytridiomycosis, is decimating amphibian populations around the world. Bd belongs to the chytrid lineage, a group of early-diverging fungi that are widely used to study fungal evolution. Like all chytrids, Bd develops from a motile form into a sessile, growth form, a transition that involves drastic changes in its cytoskeletal architecture. Efforts to study Bd cell biology, development, and pathogenicity have been limited by the lack of genetic tools with which to test hypotheses about underlying molecular mechanisms. Here, we report the development of a transient genetic transformation system for Bd. We used electroporation to deliver exogenous DNA into Bd cells and detected transgene expression for up to three generations under both heterologous and native promoters. We also adapted the transformation protocol for selection using an antibiotic resistance marker. Finally, we used this system to express fluorescent protein fusions and, as a proof of concept, expressed a genetically encoded probe for the actin cytoskeleton. Using live-cell imaging, we visualized the distribution and dynamics of polymerized actin at each stage of the Bd life cycle, as well as during key developmental transitions. This transformation system allows, for the first time, direct testing of key hypotheses regarding mechanisms of Bd pathogenesis. This technology also paves the way for answering fundamental questions of chytrid cell, developmental, and evolutionary biology.

cell biology↗

bioRxiv2018

Regulation of Cilia Abundance in Multiciliated Cells

Multiciliated cells (MCC) are specialized epithelia that contain hundreds of motile cilia used to propel fluid over the surface of the cell. To template these cilia, each MCC produces hundreds of centrioles by a process termed centriole amplification. Airway progenitor cells initially contain two parental centrioles that nucleate multiple centrioles at once, and structures called deuterosomes that assemble the vast majority of centrioles during amplification. Remarkably, how each cell regulates the precise number of its centrioles and cilia remains unknown. Here, we investigate mechanisms that establish centriole number in MCC using an ex vivo airway culture model. We show that ablation of parental centrioles, via inhibition of Plk4 kinase, does not perturb deuterosome formation and centriole amplification, nor alter the total complement of centrioles per cell. Airway MCC vary in size and surface area, and exhibit a broad range in centriole number. Quantification of centriole abundance in vitro and in vivo identified a direct relationship between cell-surface area and centriole number. By manipulating cell size and shape, we discovered that centriole number scales with increasing surface area. Collectively, our results demonstrate that parental centrioles and Plk4 are dispensable for deuterosome formation, centriole amplification, and establishment of centriole number. Instead, a cell-intrinsic surface area-dependent mechanism controls centriole and cilia abundance in multiciliated cells.

cell biology↗

bioRxiv2017

A phase separated organelle at the root of motile ciliopathy

Hundreds of different cell types emerge in the developing embryo, each of which must compartmentalize cell type specific biochemical processes in a crowded intracellular environment. To study cell type specific compartmentalization, we examined motile ciliated cells, which must assemble vast numbers of dynein motors to drive ciliary beating, as mutation of dyneins or their assembly factors causes motile ciliopathy. We show that dyneins, their assembly factors, and chaperones all concentrate together in Dynein Assembly Particles (DynAPs). These phase-separated organelles are specific to ciliated cells but share machinery with stress granules. Our data suggest that a common framework underlies ubiquitous and cell-type specific phase separated organelles and that one such organelle is defective in a human genetic disease.

cell biology↗