Research Projects

T cells are central players in adaptive immunity, orchestrating immune responses through antigen-specific recognition, clonal expansion, and effector functions. CD8⁺ T cells, in particular, mediate host defense by directly killing infected or malignant cells and are indispensable for anti-tumor immunity. At steady-state, CD8⁺ T cells have naïve, effector and memory subsets, but the effector population is most critical for anti-viral and anti-tumour responses. These effector responses are metabolically demanding and require metabolic rewiring in CD8+ T cells. While the development of CD8+ T cells in the thymus is well-studied, there is limited information on regulatory mechanisms that govern peripheral CD8⁺ T cell maintenance, differentiation and function. CD8+ T cell fate and function is regulated by transcriptional and epigenetic regulators that play a significant role in controlling specific gene expression programs. A few common molecular players such as T-bet and SWI/SNF that are repurposed to control CD8+ T cell differentiation are known; however, the knowledge in this field is still incomplete. Given the complexities, it is critical to unravel the regulatory pathways that are crucial for the differentiation and function, especially effector function, of CD8+ T cells in the periphery as this will help in designing better strategies to clear chronic viral infections and improve anti-tumor immune responses. Transcription is a torsion intensive process and resolution of DNA topological stress is critical to enable precise gene expression in immune cells. Topoisomerases (TOPs) are a class of enzymes that are essential for resolving the topological stress. Mammalian cells encode seven topoisomerases- TOP1, TOP1mt, TOP2A, TOP2B, TOP3A, TOP3B and SPO11. Topoisomerases have gained significant attention in recent times for their vital role in immune cell development and function. In our lab, we have been studying the role of TOP1 in immune system and our recent data highlights the critical role of TOP1 in thymus organogenesis and T cell development. Although, we have the data to support the role of TOP1 in thymic T cell development but its role in the maintenance and differentiation of peripheral T cells, especially CD8+ T cells, is not known. To answer this, we created a mouse model with conditional deletion of Top1 in mature CD8+ T cells. Our preliminary data highlights that loss of TOP1 in peripheral CD8+ T cells leads to decrease in their number and proportion. Transcriptomic analysis indicated the upregulation of genes involved in effector function and mitochondrial homeostasis in TOP1-deficient CD8+ T cells. In this proposal, we aim to investigate the role of TOP1 in shaping transcriptional and metabolic programs that may control the maintenance, effector function, and anti-tumor activity of peripheral CD8+ T cells. In the aim 1 of current proposal, we plan to analyse the functional phenotype of CD8+ T cells upon conditional deletion of Top1. We will perform assays to assess the cytotoxic function and analyse glucose metabolism in TOP1-deficient CD8+ T cells. In aim 2, we plan to perform scRNA-seq analysis of splenic CD8+ T cells from TOP1-sufficient and -deficient mice and this data will be complemented with TOP1 ChIP-seq and ATAC-seq assays to understand the molecular mechanism of TOP1 in regulating the effector phenotype of CD8+ T cells. In aim 3, we plan to evaluate anti-tumor properties of TOP1-deficient CD8+ T cells. We will perform both in vivo as well as ex vivo studies to assess the cytotoxic properties of TOP1-deficient CD8+ T cells against tumor. TOP1 is a druggable molecule and TOP1 inhibitors are already in clinics as anti-cancer agents. This study aims to investigate the immunomodulatory potential of selectively tuning TOP1 activity in CD8+ T cells. The findings may reveal TOP1 as a previously unrecognized immunometabolic regulator with potentially offering a new axis for cancer immunotherapy.