Biology subjects

Rashmi, R.

Publications and source records attributed to Rashmi, R..

6 recordsLinked to original sources

bioRxiv2026

Multi-compartment immune and tumor cell reprogramming by IFNa2 overcomes colon cancer immunotherapy resistance

Approximately 85-90% of colorectal cancers (CRC) are microsatellite stable and resist immune checkpoint inhibitors (ICI). The recent success of intismeran, a lipid nanoparticle (LNP)-delivered mRNA encoding patient-specific tumor antigens, enhances pembrolizumab responses, showing that LNP-delivered nucleic acids can render ICI-resistant tumors responsive by supplying what the tumor microenvironment lacks. Because an IFN-responsive phenotype predicts CRC response to checkpoint blockade and tumor cell PD-L1 represses IFN-I, we asked whether delivering the missing cytokine, rather than antigen, achieves the same conversion. Here we show that PD-1 blockade failed even when initiated before tumor seeding, yet deleting tumor cell PD-L1 abolished colon cancer lung metastasis, implicating a tumor-intrinsic PD-L1 function that antibody blockade does not neutralize. An LNP-encapsulated IFN2-encoding nanoplasmid (LNP-IFN2) transfected tumor cells within lung metastases, converting them into a self-sustaining and tumor-restricted IFN2 source. LNP-IFN2 suppressed colon cancer lung metastasis in syngeneic and humanized mouse models and sensitized these ICI-resistant tumors to PD-1 blockade. Efficacy improved further with neutralization of co-induced IL6. scRNA-Seq revealed multi-compartment reprogramming: SPP1+ macrophages acquired apoptotic signatures as IFN-responsive monocytes replaced them, progenitor-exhausted T cells exited quiescence and expanded, and tumor cells exited a high-cycling state, gained antigen presentation, and shifted away from cuproptosis resistance. The treated microenvironment transcriptionally recapitulated pembrolizumab-responder signatures, positioning LNP-IFN2 as an off-the-shelf nanomedicine for ICI-resistant CRC.

immunology↗

bioRxiv2026

B cell-intrinsic IRF8 transcriptionally reprograms antigen presentation to sustain CD8⁺ T cell antitumor immunity

Interferon regulatory factor 8 (IRF8) is a master transcription factor of myeloid differentiation, but whether IRF8 intrinsically controls B cell function in tumors remains unknown. Using paired single-cell transcriptomic and chromatin accessibility profiling of tumors from wild-type and Irf8-deficient mice, we identify a B cell-intrinsic IRF8 axis regulating antigen presentation and sustaining anti-tumor CD8 T cell immunity. IRF8 establishes conserved chromatin accessibility programs across myeloid cells and plasmablasts centered on antigen processing and MHC class I presentation, but engages distinct motifs by lineage: myeloid cells preferentially utilize ISRE and ETS-composite elements, whereas plasmablasts are selectively enriched for EICE elements, reflecting B lineage-specific IRF8-IRF4 cooperation. Loss of IRF8 disrupts these programs, skews B cells toward plasmablast differentiation and reduces antigen presentation machinery. B cell depletion accelerated tumor growth, while CD40 agonism activated B cells, expanded T cells, and enhanced anti-tumor immunity. B cell-specific IRF8 deletion alone accelerated tumor growth, establishing a cell-intrinsic requirement independent of myeloid IRF8 function. The IRF8-regulated B cell signature was enriched in PD-1 blockade cancer patient responders, and plasmablast abundance correlated with response in pembrolizumab-treated cancer patients. These findings establish IRF8 as a lineage-adapted regulator of antigen presentation and define the IRF8-B cell axis as a determinant of anti-tumor immunity. HighlightsIRF8 establishes a conserved chromatin accessibility across tumor-infiltrating myeloid and B cells Myeloid cells engage ISRE motifs, whereas plasmablasts rely on EICE motifs as IRF8 lineage-specific cis-regulation IRF8 regulates an antigen presentation in B cells to sustain anti-tumor T cell immunity B cell-intrinsic IRF8 transcription signature predicts patient response to PD-1 blockade immunotherapy

immunology↗

bioRxiv2026

Melanopsin regulates axonal translation underlying retinohypothalamic circuit assembly

Intrinsically photosensitive retinal ganglion cells (ipRGCs) influence visual system development via melanopsin before photoreceptor-mediated vision, but how melanopsin signaling contributes to ipRGC circuit assembly remains unknown. Here we show that melanopsin coordinates retinohypothalamic tract development by regulating local translation in developing ipRGC axons. Loss of melanopsin selectively disrupted local translation in axons without affecting somatic translation. The affected transcripts encoded cytoskeletal regulators, adhesion molecules, and trafficking proteins, and activity-dependent changes in translation were restricted to the period before eye-opening. Consistent with impaired axonal growth and synaptogenesis, Opn4 knockout mice showed reduced ipsilateral suprachiasmatic nucleus innervation and fewer retinohypothalamic synapses, while nanoscale synaptic molecular organization and microglial engulfment were unaffected. Reduced visual drive in Opn4 knockouts further altered developmental gene expression programs across the retina, suprachiasmatic nucleus, and lateral geniculate nucleus, with region-specific differences in expression timing. These findings identify melanopsin as a regulator of local axonal translation during early circuit development, linking sensory phototransduction to translational control mechanisms that guide retinohypothalamic tract assembly and postsynaptic target maturation.

neuroscience↗

bioRxiv2022

Pan-cancer analysis reveals the prognostic potential of THAP9/THAP9-AS1 Sense-Antisense gene pair in human cancer.

Human THAP9 is a domesticated transposon homologous to the Drosophila P-element transposase (DmTNP). However, the exact functional role of THAP9 is unknown. THAP9-AS1 (THAP9-anti sense1) is a lncRNA involved in various cancers. Together they are arranged head-to-head on opposite DNA strands forming a sense and anti-sense gene pair. No studies have analyzed THAP9 and THAP9-AS1 from a pan-cancer perspective. First, we analyzed the bidirectional promoter region between THAP9 and THAP9-AS1 for core promoter elements and CPG Islands. Moreover, we analyzed the expression, prognosis, and biological function of the two genes across different types of tumors included in The Cancer Genome Atlas and GTEx datasets. The results showed that the expression of both genes varies in different tumors. Expression of the THAP9 and THAP9-AS1 gene pair was observed to be strongly correlated with prognosis in patients with tumors; higher expression of the two genes was usually linked to poor overall and disease-free survival. Therefore, they may serve as a potential biomarker of clinical tumor prognosis. Further, we performed gene coexpression analysis using WGCNA followed by differential gene correlation analysis (DGCA) across 22 cancers to study which genes share the expression pattern THAP9 and THAP9-AS1 and if their interacting partners change in various conditions. Gene ontology & KEGG pathway analysis of genes coexpressed with the two genes identified gene enrichment related to DNA binding and Herpes simplex virus 1 infection.

bioinformatics↗

bioRxiv2021

Evolutionarily conserved regions of THAP9 transposase reveal new motifs for subcellular localization and post-translational modification.

THAP9 is a transposable element-derived gene that encodes the THAP9 protein, which is homologous to the Drosophila P-element transposase (DmTNP) and can cut and paste DNA. However, the exact functional role of THAP9 is unknown. Here, we perform evolutionary analysis and extensive in silico characterization of THAP9, including predicting domains and putative post-translational modification sites. We predict previously unreported mammalian-specific post-translational modification sites that may play a role in the subcellular localization of THAP9. We also observe that although THAP9 has evolved under a strong pervasive purifying selection, yielding high conservation of THAP9, there are distinct class-specific conservation patterns of key functional residues in certain domains. Furthermore, investigation of THAP9 expression profiles in various cancer and matched normal datasets demonstrated underexpression and overexpression in testicular cancers and thymic epithelial tumors, respectively, thus suggesting a possible role of THAP9 in cancer.

bioinformatics↗

bioRxiv2019

G-domain prediction across the diversity of G protein families

Guanine nucleotide binding proteins are characterized by a structurally and mechanistically conserved GTP-binding domain, indispensable for binding GTP. The G domain comprises of five adjacent consensus motifs called G boxes, which are separated by amino acid spacers of different lengths. Several G proteins, discovered over time, are characterized by diverse function and sequence. This sequence diversity is also observed in the G box motifs (specifically the G5 box) as well as the inter-G box spacer length. The Spacers and Mismatch Algorithm (SMA) introduced in this study, can predict G-domains in a given G protein sequence, based on user-specified constraints for approximate G-box patterns and inter-box gaps in each G protein family. The SMA parameters can be customized as more G proteins are discovered and characterized structurally. Family-specific G box motifs including the less characterized G5 motif as well as G domain boundaries were predicted with higher precision. Overall, our analysis suggests the possible classification of G protein families based on family-specific G box sequences and lengths of inter-G box spacers. Significance StatementIt is difficult to define the boundaries of a G domain as well as predict G boxes and important GTP-binding residues of a G protein, if structural information is not available. Sequence alignment and phylogenetic methods are often unsuccessful, given the sequence diversity across G protein families. SMA is a unique method which uses approximate pattern matching as well as inter-motif separation constraints to predict the locations of G-boxes. It is able to predict all G boxes including the less characterized G5 motif which marks the carboxy-terminal boundary of a G domain. Thus, SMA can be used to predict G domain boundaries within a large multi-domain protein as long as the user-specified constraints are satisfied. ClassificationBiological Sciences/Biophysics and Computational Biology

bioinformatics↗