Biology subjects

Khadilkar, R. J.

Publications and source records attributed to Khadilkar, R. J..

4 recordsLinked to original sources

bioRxiv2025

Drosophila midgut tumor-induced insulin resistance systemically remodels lymph gland hematopoiesis during cancer cachexia

Cancer cachexia involves systemic metabolic deregulation along with classical features of muscle wasting, lipolysis, and chronic inflammation. While tumor non-autonomous effects on peripheral organs are recognized, how the tumor rewires the circulating immune cells and hematopoiesis remains unclear. We utilized a Drosophila larval cancer cachexia model by expressing yki3SA in the adult midgut precursors (AMP), which gives rise to a tumor in the larval midgut and recapitulates key cachectic phenotypes, including insulin resistance. Tumor-induced cachexia results in perturbed blood cell homeostasis with a reduced niche and aberrant blood cell differentiation in the larval hematopoietic organ, the lymph gland (LG). Bulk RNA-seq analysis of circulating hemocytes from tumor-bearing larvae revealed upregulation of multiple cachectic ligands, notably ImpL2, an insulin antagonist. We demonstrate that elevated ImpL2 levels reduce LG niche size and promote aberrant blood cell differentiation. Elevated ImpL2 levels and systemic insulin resistance in the tumor-induced cachexia conditions result in abrogation of insulin signaling in the niche-progenitor micro-environment in the LG. DE-cadherin levels in the primary LG lobe are perturbed, and Wingless signaling is down-regulated, driving prohemocyte differentiation. A genetic mimic of systemic ImpL2 overexpression or high sugar diet (HSD) conditions recapitulates these LG phenotypes due to abrogation of the Insulin-Wingless signaling axis. Hemocyte-specific ImpL2 depletion in HSD-fed larvae rescued these defects, suggesting a regulatory role for circulating hemocyte-derived ImpL2. Our findings reveal that hemocyte-derived factors actively contribute to systemic insulin resistance, causing hematopoietic remodeling in cancer cachexia.

cancer biology↗

bioRxiv2025

Bendless-mediated K63 ubiquitination modulates cellular signalling to regulate Drosophila hematopoiesis

Ubiquitination is a reversible modification whose traditional role has been associated with K48-linked poly-ubiquitination involved in proteasomal degradation. However, the role of K63-linked poly-ubiquitination has been explored in various cellular processes like DNA repair, endocytosis, innate immune response, kinase activation, etc. Since K63-linked poly-ubiquitination can regulate the stability, localization, and activity of its target molecules, its regulation and function in various developmental and disease contexts are being explored. Here, we investigate how K63 ubiquitination regulates Drosophila blood cell homeostasis. Ubc13 (UBE2N), an E2 conjugating enzyme, is highly expressed in Acute Myeloid Leukemia (AML), wherein it controls innate immune signalling for the survival of AML cells; however, its role during developmental hematopoiesis is less explored. In Drosophila, Bendless is the functional homolog of Ubc13, whose role in stem cell regulation and particularly hematopoiesis is unknown. Our results indicate that spatial genetic perturbation of Bendless and its associated molecules, namely Uev1a, Effete, and E3 ligase - Traf6, that mediate K63 ubiquitination are critical for maintaining hematopoietic progenitors and regulating their differentiation. We show that Bendless-mediated K63 ubiquitination controls the Wingless signalling pathway by regulating Dishevelled in the larval lymph gland (LG) thereby modulating hematopoietic progenitor maintenance and differentiation. Furthermore, an excess of K63 ubiquitination activates the JNK pathway in the LG, resulting in lamellocyte production. Genetic epistasis analysis shows that activation of the canonical Wingless pathway in the background of Bendless depletion or inactivation of the JNK pathway in Bendless over-expression conditions can restore physiological hematopoiesis. Our findings indicate that regulators of K63 ubiquitination, like Bendless, could act as molecular inter-nodes that are capable of signalling cross-regulation, especially where intricate signalling networks are involved. Our study provides important mechanistic insights into the signalling mechanisms regulated by K63 ubiquitination during stem cell homeostasis.

developmental biology↗

bioRxiv2025

Modulation of cellular ageing regulates Integrated Stress Response signalling to control blood cell homeostasis

Organismal ageing is associated with a decline in cellular and molecular functions. One of the hallmarks of ageing is stem cell exhaustion which occurs due to dynamic changes in the stem cell - niche microenvironment. Ageing affects stem cell potency impacting self-renewal and differentiation trajectories. Blood cell homeostasis in the hematopoietic system is tightly regulated by a fine balance between stemness and differentiation. Here, we employ the Drosophila hematopoietic organ, the larval lymph gland (LG) to investigate the impact of modulating cellular ageing on organ homeostasis. LG consists of a Posterior Signalling Center (PSC) that acts as a stem cell niche and maintains the prohemocytes housed in the Medullary Zone (MZ). Cortical Zone (CZ) consists of differentiated hemocytes namely plasmatocytes, crystal cells and lamellocytes. Intricate signalling networks active in the PSC and MZ orchestrate and regulate homeostasis. In this study, we characterize the effect of genetic perturbation of the molecular circuitry of ageing locally and systemically to investigate its effect on LG blood cell homeostasis. Genetic modulation of cellular ageing displays traditional hallmarks of ageing validating our model in the LG. Our results indicate that induction of accelerated ageing both locally and systemically leads to a reduction in stem cell niche size, DNA damage accumulation and increased progenitor differentiation whereas decelerated ageing shows an opposite trend. We show that the Integrated Stress Response (ISR) pathway is activated upon inducing accelerated ageing in the LG hemocytes possibly to recoup back to homeostatic conditions. Furthermore, LGs of ISR pathway mutants or upon perturbation of ISR pathway components in prohemocytes show increased blood cell differentiation indicating disruption of homeostasis. Genetic epistasis analysis shows that ectopic over-expression of ISR pathway genes in an accelerated ageing scenario over and above the existing levels can rescue the defects in blood cell homeostasis. Overall, our study explores how modulation of cellular aging locally or systemically can impact tissue homeostasis. Our research paves way to understand the cellular mechanisms underlying an aged versus young stem cell-niche microenvironment and how its abrogation may lead to onset of disease.

developmental biology↗

bioRxiv2023

Gcn5 - mTORC1 - TFEB signalling axis mediated control of autophagy regulates Drosophila blood cell homeostasis

Blood progenitors are regulated by a variety of systemic and nutritional cues from their environment. In the Drosophila lymph gland (LG), the Posterior Signalling Center (PSC) acts as a stem cell niche striking a balance between progenitors and differentiated blood cells. Autophagy is a vital cellular process that maintains homeostasis by removing unnecessary or dysfunctional cell components through autophagic degradation and recycling. Here, using genetic perturbation analysis, we show that autophagy plays a critical role in regulating LG blood cell homeostasis. General control non-derepressible 5 (Gcn5), a histone acetyltransferase is expressed in the primary LG lobe and modulation of Gcn5 levels perturbs LG homeostasis. Our results show that hemocyte specific Gcn5 modulation controls autophagic flux in the hemocytes. Furthermore, we show that modulation of mTORC1 activity can perturb hematopoiesis. Our results indicate that organismal Gcn5 levels respond to dietary shifts and are modulated by mTORC1 signaling. Chemical intervention shows that mTORC1 over-rides the effect exerted by Gcn5 in regulating LG hematopoiesis. Taken together, our findings demonstrate that Gcn5 and mTORC1 regulates autophagy to maintain blood cell homeostasis in Drosophila.

developmental biology↗