Biology subjects

Soh, A. W. J.

Publications and source records attributed to Soh, A. W. J..

5 recordsLinked to original sources

bioRxiv2025

On-demand delivery of fibulin-1 enables repeated basement membrane stretching

Basement membrane (BM) extracellular matrices enwrap and structurally support tissues. Whether BMs are uniquely constructed to support tissues that undergo repetitive stretching and recoil events is unknown. During C. elegans ovulation, the spermathecal BM stretches [~]1.7-fold and then returns to its original shape every twenty minutes to passage hundreds of oocytes. Through live fluorescence microscopy, we discovered that ovulating oocytes secrete and deliver the fibulin-1 extracellular matrix protein to the spermathecal BM during stretching, where it forms a dynamic overlapping network with type IV collagen. Fibulin-1 depletion led to a breakdown in type IV collagen and BM organization, resulting in a more deformable BM and extended spermatheca. Moreover, perturbation to fibulin-1 network formation via mutagenesis was sufficient to disrupt organ shape. Together, our study reveals an on-demand fibulin-1 delivery system that protects the BM network when it is stretched, thereby allowing repeated rounds of organ expansion and recovery.

cell biology↗

bioRxiv2024

A complete collagen IV fluorophore knock-in toolkit reveals -chain diversity in basement membrane

The type IV collagen triple helix, composed of three -chains, is a core basement membrane (BM) component that assembles into a network within BMs. Endogenous tagging of all -chains with genetically encoded fluorophores has remained elusive, limiting our understanding of this crucial BM component. Through genome editing, we show that the C-termini of the C. elegans type IV collagen -chains EMB-9 and LET-2 can be fused to a variety of fluorophores to create a strain toolkit with wild-type health. Using quantitative imaging, our results suggest a preference for LET-2-LET-2-EMB-9 trimer construction, but also tissue-specific flexibility in trimers assembled driven by differences in -chain expression levels. By tagging emb-9 and let-2 mutants that model human Gould Syndrome, a complex multi-tissue disorder, we further discover defects in extracellular accumulation and turnover that might help explain disease pathology. Together, our findings identify a permissive tagging site that will allow diverse studies on type IV collagen regulation and function in animals. SummarySrinivasan et al., construct a collagen IV fluorophore knock-in toolkit in C. elegans using a newly identified permissive genome editing site and reveal tissue-specific -chain diversity and basement membrane turnover defects in collagen IV mutants modeling human COL4A1/A2 (Gould) syndrome.

developmental biology↗

bioRxiv2024

De novo lipid synthesis and polarized prenylation drives cell invasion through basement membrane

SummaryInvasive cells form large, specialized protrusions to break through basement membrane (BM) matrix barriers. Park et al., reveal a crucial requirement for de novo lipid synthesis and a dynamic polarizing prenylation system to rapidly construct invasive protrusions that breach BMs. To breach basement membrane (BM), cells in development and cancer use large, transient, specialized lipid-rich membrane protrusions. Using live imaging, endogenous protein tagging, and cell-specific RNAi during C. elegans anchor cell (AC) invasion, we demonstrate that the lipogenic SREBP transcription factor SBP-1 drives expression of the fatty acid synthesis enzymes POD-2 and FASN-1 prior to invasion. We show that phospholipid producing LPIN-1 and sphingomyelin synthase SMS-1, which use fatty acids as substrates, produce lysosome stores that build the ACs invasive protrusion, and that SMS-1 also promotes protrusion localization of the lipid raft partitioning ZMP-1 matrix metalloproteinase. Finally, we discover that the endoplasmic reticulum (ER)-associated HMG-CoA reductase HMGR-1, which generates isoprenoids for prenylation, enriches at the AC invasive front, and that the final ER prenylation enzyme, ICMT-1, localizes to ER exit sites that dynamically polarize to deliver prenylated GTPases for protrusion formation. Together, these results reveal a collaboration between lipogenesis and a polarized lipid prenylation system that drives invasive protrusion formation.

cell biology↗

bioRxiv2022

Intracellular connections between basal bodies promote the coordinated behavior of motile cilia

Hydrodynamic flow produced by multi-ciliated cells is critical for fluid circulation and cell motility. Hundreds of cilia beat with metachronal synchrony for fluid flow. Cilia-driven fluid flow produces extracellular hydrodynamic forces that cause neighboring cilia to beat in a synchronized manner. However, hydrodynamic coupling between neighboring cilia is not the sole mechanism that drives cilia synchrony. Cilia are nucleated by basal bodies (BBs) that link to each other and to the cells cortex via BB-associated appendages. The intracellular BB and cortical network is hypothesized to synchronize ciliary beating by transmitting cilia coordination cues. The extent of intracellular ciliary connections and the nature of these stimuli remain unclear. Moreover, how BB connections influence the dynamics of individual cilia has not been established. We show by FIB-SEM imaging that cilia are coupled both longitudinally and laterally in the ciliate Tetrahymena thermophila by the underlying BB and cortical cytoskeletal network. To visualize the behavior of individual cilia in live, immobilized Tetrahymena cells, we developed Delivered Iron Particle Ubiety Live Light-(DIPULL) microscopy. Quantitative and computer analyses of ciliary dynamics reveal that BB connections control ciliary waveform and coordinate ciliary beating. Loss of BB connections reduces cilia-dependent fluid flow forces. SummarySoh et al investigate whether intracellular connections between basal bodies control ciliary behavior in multi-ciliated cells. Using a Tetrahymena live cell immobilization technique to quantify ciliary dynamics, they show that inter-BB connections are required for effective ciliary waveform and coordinated ciliary beating that promotes fluid flow.

cell biology↗

bioRxiv2019

Microtubule glycylation promotes basal body attachment to the cell cortex

Motile cilia generate directed hydrodynamic flow that is important for the motility of cells and extracellular fluids. To optimize directed hydrodynamic flow, motile cilia are organized and oriented into a polarized array. Basal bodies (BB) nucleate and position motile cilia at the cell cortex. Cytoplasmic BB-associated microtubules are conserved structures that extend from BBs. Using the ciliate, Tetrahymena thermophila, combined with EM-tomography and light microscopy, we show that BB-appendage microtubules assemble coincident with new BB assembly and are attached to the cell cortex. These BB-appendage microtubules are specifically marked with post translational modifications of tubulin, including glycylation. Mutations that prevent glycylation shorten BB-appendage microtubules and disrupt BB positioning and cortical attachment. Consistent with the attachment of BB-appendage microtubules to the cell cortex for BB positioning, mutations that disrupt the cellular cortical cytoskeleton similarly disrupt the cortical attachment and positioning of BBs. In summary, BB-appendage microtubules promote the organization of ciliary arrays through attachment to the cell cortex.\n\nSUMMARY STATEMENTBasal bodies position motile cilia at the cell cortex. This study finds tubulin glycylation to promote BB-associated microtubule elongation and structural attachment of basal bodies to the cells cortical cytoskeleton.

cell biology↗