Biology subjects

Bhoi, R.

Publications and source records attributed to Bhoi, R..

3 recordsLinked to original sources

bioRxiv2025

Hyperexcitability in Alzheimers Disease triggers a compensatoryneuroprotective response via TREK1

Alzheimers Disease (AD) is marked by early hippocampal and neocortical accumulation of amyloid-beta 42 oligomers (A{beta}42o), driving neuronal hyperactivity and synaptic dysfunction years before symptom onset. While two-pore domain leak potassium channels like TREK1 are crucial for maintaining the resting membrane potential of neurons and shaping their excitability profile, their role in major neurodegenerative disorders like AD remains unknown. Here, we discover an activity-dependent upregulation of TREK1 in AD transgenic mice (3xTg and APP/PS1) and cultured hippocampal/cortical neurons, triggered by A{beta}42o -induced hyperactivity. Mechanistically, we show that increased intracellular calcium activates adenylate cyclase 1/8 (AC1/8), initiating a cAMP-PKA signaling cascade that enhances the expression of chromatin regulator CTCF. This increased CTCF in turn enhances the expression of TREK1 both in vitro and in AD transgenic mice. Through a combination of calcium imaging, patch-clamp electrophysiology, immunostaining, and cognitive assays in a hippocampal TREK1 knockdown AD model, we establish that the pathology-associated upregulation of TREK1 constitutes a critical homeostatic brake on neuronal hyperexcitability. This neuronal response is essential for limiting A{beta}42o-mediated synaptic pathology and delaying cognitive decline. Our study identifies a multi-step signaling cascade triggered by A{beta}42o leading to upregulation of TREK1 that functions as an essential compensatory mechanism for neuronal survival in early AD. This study deciphers a cellular mechanism responsible for the preclinical phase of AD characterized by silent buildup of pathology.

neuroscience↗

bioRxiv2024

Generative AI for Cardiac Organoid Florescence Generation

AbstractHuman pluripotent stem cell (hPSC)-derived cardiac organoid is the most recent three-dimensional tissue structure that mimics the structure and functionality of the human heart and plays a pivotal role in modeling heart development and disease. The hPSC-derived cardiac organoids are commonly characterized by bright-field microscopic imaging for tracking daily organoid differentiation and morphology formation. Although the brightfield microscope provides essential information about hPSC- derived cardiac organoids, such as morphology, size, and general structure, it does not extend our understanding of cardiac organoids on cell type-specific distribution and structure. Then, fluorescence microscopic imaging is required to identify the specific cardiovascular cell types in the hPSC-derived cardiac organoids by fluorescence immunostaining fixed organoid samples or fluorescence reporter imaging of live organoids. Both approaches require extra steps of experiments and techniques and do not provide general information on hPSC-derived cardiac organoids from different batches of differentiation and characterization, which limits the biomedical applications of hPSC-derived cardiac organoids. This research addresses this limitation by proposing a comprehensive workflow for colorizing phase contrast images of cardiac organoids from brightfield microscopic imaging using conditional Generative Adversarial Networks (GANs) to provide cardiovascular cell type-specific information in hPSC-derived cardiac organoids. By infusing these phase contrast images with accurate fluorescence colorization, our approach aims to unlock the hidden wealth of cell type, structure, and further quantifications of fluorescence intensity and area, for better characterizing hPSC-derived cardiac organoids.

bioengineering↗

bioRxiv2022

Micropatterned Organoids Enable Modeling of the Earliest Stages of Human Cardiac Vascularization

Although model organisms have provided insight into the earliest stages of cardiac vascularization, we know very little about this process in humans. Here we show that spatially micropatterned human pluripotent stem cells (hPSCs) enable in vitro modeling of this process, corresponding to the first three weeks of in vivo human development. Using four hPSC fluorescent reporter lines, we create cardiac vascular organoids (cVOs) by identifying conditions that simultaneously give rise to spatially organized and branched vascular networks within endocardial, myocardial, and epicardial cells. Using single-cell transcriptomics, we show that the cellular composition of cVOs resembles that of a 6.5 post-conception week (PCW) human heart. We find that NOTCH and BMP pathways are upregulated in cVOs, and their inhibition disrupts vascularization. Finally, using the same vascular-inducing factors to create cVOs, we produce hepatic vascular organoids (hVOs). This suggests there is a conserved developmental program for creating vasculature within different organ systems. Graphic Abstract O_FIG O_LINKSMALLFIG WIDTH=159 HEIGHT=200 SRC="FIGDIR/small/499233v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@17b265org.highwire.dtl.DTLVardef@1c1113eorg.highwire.dtl.DTLVardef@531c18org.highwire.dtl.DTLVardef@596bd2_HPS_FORMAT_FIGEXP M_FIG C_FIG

developmental biology↗