Biology subjects

Radhakrishnan, D.

Publications and source records attributed to Radhakrishnan, D..

5 recordsLinked to original sources

bioRxiv2025

Hepatocyte-like cells die via steroid hormone and nuclear receptor E75-mediated apoptosis

Metabolic organs must sustain physiological function while retaining the capacity for timely cell death. Systemic hormones play a key role in coordinating this balance, yet how they regulate cell death in vivo remains unclear. Here, we investigate hormone-regulated cell death in a metabolically specialised organ using Drosophila oenocytes, polyploid hepatocyte-like cells, as a tractable in vivo model. Using non-invasive longitudinal live imaging combined with oenocyte-specific genetic manipulation, we directly visualise larval oenocyte death during metamorphosis. We show that larval oenocyte loss is a dynamic, multistep process controlled by the steroid hormone ecdysone. We further identify the ecdysone-induced nuclear receptor E75 as a key regulator of the timing of cell death, as loss of E75 triggers premature oenocyte death. Oenocyte-specific manipulation of cell death pathways, together with live imaging using genetically encoded caspase reporters, provides direct evidence that larval oenocytes die by apoptosis. Together, this work defines how systemic hormonal signals regulate the timing of apoptosis in metabolically specialised polyploid cells and establishes oenocytes as a powerful in vivo system for studying cell death in metabolic organs.

developmental biology↗

bioRxiv2023

Cell competition for cancer treatment with Urine Progenitor Cells

Here, we provide evidence that urine progenitor cells (UPCs) might offer a novel therapeutic strategy for treating different types of cancer. We found that UPCs have inherent antitumor properties due to cell-cell competition, and we described their mechanism of action against different tumor cell lines. In vitro time-lapse analysis showed that the UPCs have tumor tropic properties, homing to various tumor-conditioned mediums. Besides, UPCs engineered for the expression of cytotoxic agents (the Tumor Necrosis Factor ligand superfamily member 10 and Herpesvirus-thymidine kinase) significantly increased their antitumor properties against several tumor cell lines and proved to serve as highly effective drug-delivery vehicles. Finally, using a mouse model of human triple-negative breast cancer, we observed a 150-fold decrease in tumor volumes in mice treated with engineered UPCs compared to controls. Collectively, our findings demonstrate for the first time the antitumor properties of the UPCs and form a foundation to continue exploring the new concept of cell-cell competition in progenitor cells to treat different types of cancer.

cancer biology↗

bioRxiv2022

Restoration of beta-GC trafficking improves the lysosome function in Gaucher disease

Lysosomes function as a primary site for catabolism and cellular signaling. These organelles digest a variety of substrates received through endocytosis, secretion and autophagy with the help of resident acid hydrolases. Lysosomal enzymes are folded in the endoplasmic reticulum (ER) and trafficked to lysosomes via Golgi and endocytic route. The inability of hydrolase trafficking due to mutations or mutations in its receptor or cofactor leads to cargo accumulation (storage) in lysosomes, resulting in lysosome storage disorder (LSD). In Gauchers disease (GD), the lysosomes accumulate glucosylceramide due to a lack of {beta}-glucocerebrosidase ({beta}-GC) activity that causes lysosome enlargement/dysfunction. We hypothesize that improving the trafficking of mutant {beta}-GC to lysosomes may delay the progression of GD. RNAi screen using high throughput based lysosomal enzyme activity assay followed by reporter trafficking assay utilizing {beta}-GC-mCherry lead to the identification of nine potential phosphatases. Depletion of these phosphatases in HeLa cells enhanced the {beta}-GC activity by increasing the folding and trafficking of Gauchers mutants to the lysosomes. Consistently, the lysosomes in primary fibroblasts from GD patients restored their function upon the knockdown of these phosphatases. Thus, these studies provide evidence that altering phosphatome activity possibly delays the GD and forms an alternative therapeutic strategy for this genetic disease. Key pointsO_LIPhosphatome RNAi screen identified both activators and inhibitors of cellular glucocerebrosidase activity C_LIO_LIDepletion of selective phosphatases in HeLa cells improved the folding and trafficking of mutant {beta}-glucocerebrosidase to lysosomes C_LIO_LIKnockdown of selective phosphatases restored the low basal {beta}-glucocerebrosidase activity to that of wild-type in primary cells derived from Gauchers disease patients C_LIO_LIDepletion of selective phosphatases displayed variable {beta}-GC activity in neuropathic and non-neuropathic Gauchers disease patient cells C_LI

cell biology↗

bioRxiv2020

Regulation of touch dependant de novo root regeneration in Arabidopsis

The versatile regeneration capability of leaves enable even a detached Arabidopsis leaf to yield two kinds of regenerative responses namely, wound healing at the cut end in form of callus formation or de novo root regeneration (DNRR). Using various experimental approaches, we show that the factor favouring DNRR over callus formation seems to be a mechanical cue, possibly touch, at the cut end of the detached leaf. Here, we show that the forced expression of a PLETHORA transcription factor can bypass the need for touch to initiate DNRR. Our findings provide a genetic frame-work for touch dependant DNRR and suggest that a core PLT transcription regulatory module acts in response to mechano-sensing stimuli.

plant biology↗

bioRxiv2020

Age, wound size and position of injury - dependent vascular regeneration assay in growing leaves

BackgroundRecurring damage to aerial organs of plants necessitates their prompt repair, particularly their vasculature. While vascular regeneration assay in aerial plant parts such as stem and inflorescence stalk are well established, those on leaf vasculature remained unexplored. Recently we established a new vascular regeneration assay in growing leaf and discovered the underlying molecular mechanism. ResultsHere we describe the detailed stepwise method of incision and the regeneration assay used for studying the leaf vascular regeneration. By using a combination of micro-surgical perturbations, brightfield microscopy and other experimental approaches, our new findings show that the regeneration efficiency decreases with aging of the leaf, and increases with the nearness of the wound towards the proximal end of the leaf. ConclusionThis easy-to-master vascular regeneration assay is an efficient and rapid method to study the mechanism of vascular regeneration in growing leaves. It can be readily adapted for other plant species and can be combined with cellular and molecular biology techniques.

plant biology↗