Biology subjects

Murthy, V.

Publications and source records attributed to Murthy, V..

5 recordsLinked to original sources

bioRxiv2026

Spatially coordinated RTK-ERK signaling dynamics shape osteosarcoma single-cell drug response in the lung microenvironment

Purpose: Lung metastases are the primary cause of death in osteosarcoma patients and treatment response often vary due to convergence of genetic and phenotypic influences in the context of a dynamic tumor-host tissue environment. The purpose of this study was to determine how dynamic tumor- and host-driven receptor tyrosine kinase (RTK)-ERK signaling interactions contribute to phenotypic drug response heterogeneity. Experimental Design: Live-cell time-lapse microscopy and data-driven dynamical modeling was used to resolve ERK activity, FOSL1/Fra-1 reporter expression, and spatiotemporal cell fate in living, biosensor-expressing osteosarcoma lung metastases ex vivo following MCL1 inhibitor exposure. RTK inhibitors were then evaluated for their ability to suppress adaptive signaling and enhance MCL1 inhibitor efficacy ex vivo and in vivo. Results: MCL1 inhibition induced extensive tumor-cell death; however, persistent ERKhigh/Fra-1high reporter cells emerged and were enriched at the tumor-lung interface, consistent with adaptive resistance. Experimental and computational approaches revealed that tumor-cell lysis amplified fibroblast growth factor receptor (FGFR)-mediated ERK signaling in neighboring cells, promoting a targetable drug-resistant state marked by adaptive ERK induction, FOSL1/Fra-1 expression, and correlated with upregulation of known drug resistance pathways Nrf2 and HMOX1. Combinatorial inhibition of FGFR with fexagratinib, or broad-spectrum RTK inhibitor, pazopanib, suppressed adaptive ERK activation and enhanced MCL1 inhibitor response resulting in greater efficacy ex vivo and in vivo. Conclusions: Tumor-host and tumor-cell-lysis-induced FGFR-ERK signaling contribute to spatiotemporally heterogeneous adaptive resistance in metastatic osteosarcoma. These data support combinatorial targeting of RTK signaling with cytotoxic or targeted agents as a strategy to block adaptive resistance and improve treatment efficacy.

cancer biology↗

bioRxiv2026

A Compact, Standalone & Battery-Powered 3D Organoid-on-Chip System with Programmable Flow Control

Organoids-on-chip combine the 3D complex microenvironment and cellular composition of organoids with microfluidic flow, increasing nutrient-waste exchange and mimicking the contributions of in vivo interstitial and vascular flow. However, the widespread adoption of organoid-on-chip platforms is limited by the lack of incubator-friendly flow control systems. Existing approaches often rely on commercially available syringe or peristaltic pumps, but these are bulky, lack scalability, and present a significant barrier for clinical translation. To circumvent these issues, we present the Compact Active Perfusion Standalone Organoid-on-Chip (CAPS-OC) platform, a fully integrated and battery-powered microfluidic system capable of culturing organoids in active media flow. To achieve this, we introduce a novel low-power mechanism of pressure pulse generation using an off-the-shelf compact rotary actuator (CRA), and package it into a compact electromechanical assembly. This assembly provides timed pneumatic inputs to achieve programmable control of membrane-based peristaltic pumps, with [~]100 {micro}L/hr dynamic range achieved on a custom microfluidic organoid chip. We biologically validated this system by culturing pancreatic cancer organoids derived from a KrasLSL-G12D/+; Trp53LSL-R172H/WT; Pdx1-Cre (KPC) genetically engineered mouse model. We found that our chip enhances proliferation and helps sustain a population of larger (>150 {micro}m) organoids compared to standard dome based static culture. Additionally, through immunostaining, we observe that KPC organoids cultured in the chip show more aggressive PDAC phenotype with reduced nuclear expression of GATA6, whereas organoids in static culture retain less aggressive classical- like subtype. Finally, testing of a RAS inhibitor drug, daraxonrasib, on the KPC organoids on chip showed size-based sensitivity elucidating the impact of active perfusion on the drug diffusion kinetics. Altogether, we establish CAPS-OC as a valuable tool for the bioengineering community and for clinically translating organoid model systems.

bioengineering↗

bioRxiv2026

IP3R-TRPM4 Coupling Determines the Spatial Reach of Pericyte-Mediated Capillary Constriction

Ensheathing pericytes extend multiple projections that wrap around capillary vessels to regulate diameter and direct blood flow distribution across the microvascular network. At capillary bifurcations, individual projections wrap around branches of different diameters, positioning the pericyte to simultaneously regulate multiple vessel segments. Using optogenetic tools in acta2-opto-1AR and acta2-CatCh mice, we show that Gq-coupled receptor activation confines contractile responses to the projection receiving the stimulus, whereas direct membrane depolarization propagates to projections wrapping neighboring capillary branches via gap junction-independent mechanisms. Computational modeling revealed that TRPM4, a Ca2+-activated nonselective cation channel, uniquely couples local Ca2+ signals to voltage-gated Ca2+ channel activation in projections on neighboring branches at physiologically relevant channel abundances. Ca2+ imaging identified two kinetically distinct event populations: slow, low-amplitude IP3R-mediated events and fast, high-amplitude VGCC-mediated transients. Sustained low-amplitude signals selectively maintained TRPM4 activation and enabled cross-projection propagation, whereas brief high-amplitude transients drove rapid channel inactivation. Proximity ligation assays confirmed nanoscale colocalization of TRPM4 and IP3 receptors in pericytes. Focal IP3 photolysis produced constriction across projections wrapping multiple capillary branches that was abolished by TRPM4 blockade and enhanced by PKC-mediated augmentation of TRPM4 expression. These findings identify an IP3R-TRPM4 signaling axis as a molecular switch that gates whether capillary constriction remains branch-specific or coordinates across the pericyte, enabling precise stimulus-dependent control of blood flow distribution in the microvasculature.

physiology↗

bioRxiv2025

Serial Imaging of Tumor and microEnvironment (SITE) platform for live-cell ex vivo modeling of primary and metastatic cancer dynamics.

Understanding cancer initiation and progression is extremely challenging, in part due to experimental limitations in measuring and interpreting key signalling and tumour-microenvironment (TME) interactions that determine changes in cell and tissue behaviours over time. Here we developed SITE (Serial Imaging of Tumour and microEnvironment), a spatially-and temporally integrated, modular, ex vivo platform enabling quantitative analysis of TME interaction dynamics, signalling, and cell fate at single cell and tissue scales. Applied to modelling primary and lung metastatic breast cancer, SITE revealed tissue-specific TME interactions and ERK signalling patterns linked to distinct single-cell behaviours. We found that the earliest steps in tumour establishment and metastatic seeding involved active cell protrusion and the establishment of a multicellular niche interfacing tumour and host. Experimental and mathematical modelling showed that ERK signalling was co-influenced by these interactions, where cancer cluster formation increased signalling via the establishment of local signalling circuits. Disruption of these signalling circuits led to tissue-specific impacts on cancer intrinsic and TME interaction dynamics. Here, we modelled breast cancer as a test case, demonstrating the broad utility of SITE for quantitative exploration of TME interaction dynamics- closing a significant gap in experimental capabilities between in vivo models and in vitro systems.

cancer biology↗

bioRxiv2018

Hypomorphic mutation of the mouse Huntingtons disease gene orthologue

Rare individuals with hypomorphic inactivating mutations in the Huntingtons Disease (HD) gene (HTT), identified by CAG repeat expansion in the eponymous neurodegenerative disorder, exhibit variable abnormalities that imply HTT essential roles during organ development. Here we report phenotypes produced when increasingly severe hypomorphic mutations in Htt, the murine HTT orthologue (in HdhneoQ20, HdhneoQ50, HdhneoQ111 mice), were placed over a null allele (Hdhex4/5). The most severe hypomorphic allele failed to rescue null lethality at gastrulation, while the intermediate alleles yielded perinatal lethality and a variety of fetal abnormalities affecting body size, skin, skeletal and ear formation, and transient defects in hematopoiesis. Comparative molecular analysis of wild-type and Htt-null retinoic acid-differentiated cells revealed gene network dysregulation associated with organ development and proposed polycomb repressive complexes and miRNAs as molecular mediators. Together these findings demonstrate that the HD gene acts both pre- and post-gastrulation and possibly suggest pleiotropic consequences of HTT-lowering therapeutic strategies.\n\nAuthor SummaryThe HTT gene product mutated in Huntingtons Disease (HD) has essential roles during normal organism development, however, still not fully predictable are the functional consequences of its partial inactivation. Our genetic study provides a comprehensive effects description of progressively stronger suppression of Htt gene, the murine HTT counterpart. The most severe Htt reduction leads to embryo lethality, while intermediate Htt dosages yield a variety of developmental abnormalities affecting body size, skin, skeletal and ear formation, and hematopoiesis. Complementing molecular analysis in differentiating cells depleted of a functional Htt gene further elucidates genes networks dysregulated during organ development and proposes chromatin regulators and short non-coding RNAs as key molecular mediators. Together these findings demonstrate that the HD gene acts both at early and later stages of development, thus possibly suggesting long-term consequences associated to the newest HD therapeutic strategies aimed at lowering the HTT gene product.

genetics↗