Biology subjects

Sonawane, M.

Publications and source records attributed to Sonawane, M..

9 recordsLinked to original sources

bioRxiv2026

ROCK-mediated junctional remodelling preserves barrier function in a developing epithelium during hypoxia

Epithelia contribute to organismal homeostasis by functioning as selectively permeable barriers. Being avascular, epithelia are particularly vulnerable to hypoxia. Yet how developing epithelia adapt to preserve tissue integrity under hypoxic conditions remains elusive. Here, we show that in bilayered zebrafish epidermis hypoxia disrupts epithelial architecture reversibly, but preserves tight junction-mediated barrier function. ROCK maintains the tight apico-cortical localisation of active Non-muscle myosin-II (pNM-II) to mediate a squamous-to-cuboidal shape transition in epithelial cells under hypoxia. It further suppresses Crb3-dependent local force imbalance that otherwise results in cell delamination and cell-rosette formation. Importantly, we identify ROCK as a regulator that promotes barrier function maintenance specifically under hypoxia. Our genetic analyses demonstrate that ROCK primarily coordinates junctional remodelling to maintain barrier function during hypoxia while actomyosin contractility may foster the junctions secondarily. We propose that under an energy constrained hypoxic environment, dismantling E-cadherin based adhesion and augmenting ROCK-dependent barrier function in a developing epithelium ensures organism survival allowing recovery when normoxic conditions resume.

Cell Biology↗

bioRxiv2025

Developing epidermis acquires nutrients from the external milieu by mTOR-dependent macropinocytosis

The vertebrate epidermis transitions from a simple bilayer to a complex, multilayered epithelium during development. Periderm, the outermost layer of the bilayered epidermis, is in direct contact with the external aquatic surrounding. While the barrier function of the epidermis is well established, the functional repertoire of the developing epidermis remains unclear. Using zebrafish, we uncover a function of the periderm in nutrient acquisition. Our findings reveal a developmentally regulated wave of macropinocytosis, which is further amplified by extracellular nutrients, leading to the formation of large endo-lysosomal compartments termed Stimulated Nutrient Activated Compartments (SNACs). We identify mTOR as a key integrator of developmental and nutrient-derived signals that modulate SNAC biogenesis. A global lipidomics analysis demonstrates that macropinocytosis-mediated uptake drives the production of metabolically relevant lipids and enhances animal survival when gut function is compromised. Our study identifies a hitherto unappreciated route of nutrient acquisition by the metabolically responsive developing epidermis. We propose that this mechanism fulfils a vital nutritional role, particularly during the transitional phase when maternally provided resources are depleting and the gut is not yet fully operational.

developmental biology↗

bioRxiv2024

mTOR signaling governs the formation of epithelial apical projection via S6K1-RhoA and aPKC-Lgl2 axes

In metazoans, epithelia perform functions of absorption, diffusion, and secretion. The actin-based apical projections on the epithelial cells, contribute to these functions and are formed via cell-autonomous mechanisms that control cell polarity, intracellular transport, and the cytoskeleton. However, the cues that function upstream of these cell-autonomous regulators remain poorly known. Using microridges on zebrafish epithelial cells as a paradigm, we show that mTOR, a metabolic sensor, regulates the formation of apical projections. Mechanistically, mTORC1 controls the RhoA-ROCK activity via S6K1 to prevent the overactivation of Non-muscle Myosin II (NMII) to restrict microridge elongation. Furthermore, genetic, biochemical, and molecular dynamics simulation analyses reveal that mTORC2 regulates microridge pattern by modulating the activity of aPKC via its differential phosphorylation at two conserved sites. We propose that mTOR integrates the developmental and/or metabolic status of epithelial cells with cell autonomously acting RhoA and aPKC to regulate tissue wide formation of apical projections.

cell biology↗

bioRxiv2024

Consumption of human-relevant levels of sucrose-water rewires macronutrient uptake and utilization mechanisms in a tissue specific manner

Consumption of sugar-sweetened beverages (SSBs) have been linked to metabolic dysfunction, obesity, diabetes and enhanced risk of cardiovascular diseases across all age-groups globally. Decades of work that have provided insights into pathophysiological manifestations of sucrose overfeeding have employed paradigms that rarely mimic human consumption of SSBs. Thus, our understanding of multi-organ cross-talk and molecular and/or cellular mechanisms, which operate across scales and drive physiological derangement is still poor. By employing a paradigm of sucrose water feeding in mice that closely resembles chronic SSB consumption in humans (10% sucrose in water), we have unraveled hitherto unknown tissue-specific mechanistic underpinnings, which contribute towards perturbed physiology. Our findings illustrate that systemic impaired glucose homeostasis, mediated by hepatic gluconeogenesis and insulin resistance, does not involve altered gene expression programs in the liver. We have discovered the pivotal role of the small intestine, which in conjunction with liver and muscles, drives dyshomeostasis. Importantly, we have uncovered rewiring of molecular mechanisms in the proximal intestine that is either causal or consequential to systemic ill-effects of chronic sucrose water consumption including dysfunction of liver and muscle mitochondria. Tissue-specific molecular signatures, which we have unveiled, clearly indicate that inefficient utilization of glucose is exacerbated by enhanced uptake by the gut. Besides providing systems-wide mechanistic insights, we propose that consumption of SSBs causes intestinal molecular addiction for deregulated absorption of hexose-sugars, and drives diseases such as diabetes and obesity.

physiology↗

bioRxiv2024

STIPS algorithm enables tracking labyrinthine patterns and reveals distinct rhythmic dynamics of actin microridges

Tracking and motion analyses of semi-flexible biopolymer networks from time-lapse microscopy images are important tools that enable quantitative measurements to unravel dynamical and mechanical properties of biopolymers in living tissues important for understanding their organization and function. Biopolymer networks pose tracking challenges as they exhibit continuous stochastic transitions in the form of merges/splits resulting in local neighborhood rearrangements over short time/length scales. We propose the STIPS algorithm (SpatioTemporal Information on Pixel Subsets) that tracks merging/splitting events in self-organizing patterning systems, by creating pixel subsets to link trajectories across consecutive frames. We demonstrate our method on actin-enriched protrusions, the microridges that form dynamic labyrinthine patterns on outer surfaces of squamous cell epithelia, mimicking active Turing-patterns. We uncovered two distinct actomyosin based rhythmic dynamics within neighboring cells; common pulsatile mechanism between 2-5.9 mins period governing both fusion and fission contributing to pattern maintenance and cell area pulses predominantly exhibiting [~]10 mins period.

developmental biology↗

bioRxiv2021

A deep learning framework for quantitative analysis of actin microridges

Microridges are evolutionarily conserved actin-rich protrusions present on the apical surface of the squamous epithelial cells. In zebrafish epidermal cells, microridges form self-evolving patterns due to the underlying actomyosin network dynamics. However, their morphological and dynamic characteristics have remained poorly understood owing to lack of automated segmentation methods. We achieved ~97% pixel-level accuracy with the deep learning microridge segmentation strategy enabling quantitative insights into their bio-physical-mechanical characteristics. From the segmented images, we estimated an effective microridge persistence length as ~0.61m. We discovered the presence of mechanical fluctuations and found relatively greater stresses stored within patterns of yolk than flank, indicating distinct regulation of their actomyosin networks. Furthermore, spontaneous formations and positional fluctuations of actin clusters within microridge influenced pattern rearrangements over short length/time-scales. Our framework allows large-scale spatiotemporal analysis of microridges during epithelial development and probing of their responses to chemical and genetic perturbations to unravel the underlying patterning mechanisms.

developmental biology↗

bioRxiv2021

Ligand geometry dictates cellular and in vivo uptake of 3D DNA nanostructures

Fabrication of nanoscale DNA devices to generate 3D nano-objects with precise control of shape, size, and presentation of ligands has shown tremendous potential for therapeutic applications. The interactions between different topologies of 3D DNA nanostructures and the cell membranes are crucial for designing efficient tools for interfacing DNA devices with biological systems. The practical applications of these DNA nanocages are still limited in cellular and biological systems owing to the limited understanding of interactions of different surface topologies of DNA nanodevices with cell membranes. The correlation between the geometry of DNA nanostructures and their internalization efficiency remains elusive. We investigated the influence of the shape and size of 3D DNA nanostructure on their cellular internalization efficiency. We found that of different geometries designed, one particular geometry, i.e., the tetrahedral shape, is more favoured over other geometries for their cellular uptake in 2D and 3D cell models. This is also replicable for cellular processes like 3D cell invasion assays in 3D spheroid models and passing the epithelial barriers in in-vivo zebrafish model systems. Our work establishes ground rules for the rational designing of DNA nanodevices for their upcoming biological and biomedical applications.

bioengineering↗

bioRxiv2020

Satb2 acts as a gatekeeper for major developmental transitions during early vertebrate embryogenesis

Zygotic genome activation (ZGA) initiates regionalized transcription responsible for the acquisition of distinct cellular identities. ZGA is dependent upon dynamic chromatin architecture sculpted by conserved DNA-binding proteins. However, whether the tissue-specific transcription is mechanistically linked with the onset of ZGA is unknown. Here, we have addressed the involvement of chromatin organizer SATB2 in orchestrating these processes during vertebrate embryogenesis. Integrative analysis of transcriptome, genome-wide occupancy and chromatin accessibility revealed contrasting molecular functions of maternal and zygotic pools of Satb2. Maternal Satb2 represses zygotic genes by influencing the interplay between the pluripotency factors. By contrast, zygotic Satb2 activates transcription of the same group of genes during neural crest development and organogenesis. Comparative analysis of maternal versus zygotic function of Satb2 underscores how these antithetical activities are temporally coordinated and functionally implemented. We discuss the evolutionary implications of the biphasic and bimodal regulation of landmark developmental transitions by a single determinant.

developmental biology↗

bioRxiv2018

Microridges are apical projections formed of branched F-actin networks that organize the glycan layer

Apical projections are integral functional units of epithelial cells. Microvilli and stereocilia are cylindrical apical projections that are formed of bundled actin. Microridges on the other hand, grow laterally long, forming labyrinthine patterns on surfaces of various kinds of squamous epithelial cells. So far, the structural organization and functions of microridges have remained elusive. We have analyzed microridges on zebrafish epidermal cells using confocal and electron microscopy methods including electron tomography, to show that a microridge is formed of a network of F-actin and requires the function of the Arp2/3 complex for its maintenance. During development, microridges begin as F-actin punctae showing signatures of branching and requiring an active Arp2/3 complex. Using inhibitors of actin polymerization and the Arp2/3 complex, we show that microridges organize the surface glycan layer. Our analyses have unraveled the F-actin organization supporting the most abundant and evolutionarily conserved apical projection, which functions in glycan organization.

cell biology↗