Biology subjects

Singh, N.

Publications and source records attributed to Singh, N..

At least 73 records · Page 4Linked to original sources

bioRxiv2024

An RNAi screen of Rab GTPase genes in C. elegans reveals that somatic cells of the reproductive system depend on rab-1 for morphogenesis but not stem cell niche maintenance

Membrane trafficking is a crucial function of all cells and is regulated at multiple levels from vesicle formation, packaging, and localization to fusion, exocytosis, and endocytosis. Rab GTPase proteins are core regulators of eukaryotic membrane trafficking, but developmental roles of specific Rab GTPases are less well characterized, potentially because of their essentiality for basic cellular function. C. elegans gonad development entails the coordination of cell growth, proliferation, and migration--processes in which membrane trafficking is known to be required. Here we take an organ-focused approach to Rab GTPase function in vivo to assess the roles of Rab genes in reproductive system development. We performed a whole-body RNAi screen of the entire Rab family in C. elegans to uncover Rabs essential for gonad development. Notable gonad defects resulted from RNAi knockdown of rab-1, the key regulator of ER-Golgi trafficking. We then examined the effects of tissue-specific RNAi knockdown of rab-1 in somatic reproductive system and germline cells. We interrogated the dual functions of the distal tip cell (DTC) as both a leader cell of gonad organogenesis and the germline stem cell niche. We find that rab-1 functions cell-autonomously and non-cell-autonomously to regulate both somatic gonad and germline development. Gonad migration, elongation, and gamete differentiation--but surprisingly not germline stem niche function--are highly sensitive to rab-1 RNAi. SUMMARYThe Rab family of GTPases regulate vesicular trafficking in cells. This study assessed the consequences for the growth of the gonad of RNAi-mediated gene knockdown of all Rab GTPase genes in C. elegans. The highly conserved primary regulator of ER-Golgi trafficking, rab-1, is essential for normal gonad and germline development. Further experiments found that rab-1 is required in the somatic gonad for gonad elongation and migration, germline proliferation, and proper gamete formation. Surprisingly, the ability of the germline stem cell niche to maintain germ cells in the proliferative stem-like state was not affected by rab-1 RNAi knockdown.

developmental biology↗

bioRxiv2024

Mapping Plasmodium transitions and interactions in the Anopheles female

The human malaria parasite, Plasmodium falciparum, relies exclusively on Anopheles mosquitoes for transmission. Once ingested during blood feeding, most parasites die in the mosquito midgut lumen or during epithelium traversal1. How surviving ookinetes interact with midgut cells and form oocysts is poorly known, yet these steps are essential to initiate a remarkable growth process culminating in the production of thousands of infectious sporozoites2. Here, using single-cell RNA sequencing of both parasites and mosquito cells across different developmental stages and metabolic conditions, we unveil key transitions and mosquito-parasite interactions occurring in the midgut. Functional analyses uncover processes regulating oocyst growth and identify the transcription factor PfSIP2 as essential for sporozoite infection of human hepatocytes. Combining shared mosquito-parasite barcode analysis with confocal microscopy, we reveal that parasites preferentially interact with midgut progenitor cells during epithelial crossing, potentially using their basal location as an exit landmark. Additionally, we show tight connections between extracellular late oocysts and surrounding muscle cells that may ensure parasites adherence to the midgut. We confirm our major findings in several mosquito-parasite combinations, including field-derived parasites. Our study provides fundamental insight into the molecular events characterizing previously inaccessible biological transitions and mosquito-parasite interactions, and identifies candidates for transmission-blocking strategies.

microbiology↗

bioRxiv2024

Peptide modified, programmable DNA tetrahedra to modulate autophagy in biological systems

Autophagy is a critical cellular pathway for degrading and recycling damaged components, essential for maintaining cellular homeostasis. Dysregulation of autophagy contributes to various diseases, including neurodegenerative disorders, cancers, and metabolic syndromes, highlighting the therapeutic potential of controlled autophagy induction. However, current autophagy inducers often lack specificity and may inadvertently trigger apoptosis, limiting their clinical utility. Here, we present a DNA tetrahedron-BH3 peptide nanosystem (Tdpep) engineered to selectively induce autophagy by disrupting the Beclin 1-Bcl2 interaction, a pivotal regulatory point in autophagy initiation. Tdpep, functionalized with a BH3 peptide targeting Bcl2, demonstrated efficient cellular uptake and minimal cytotoxicity in HeLa cells at concentrations up to 200nM. Autophagy induction was confirmed by increased LC3B puncta formation and fluorescence intensity comparable to that induced by rapamycin. Autophagy flux analysis of Tdpep with bafilomycin A1 validated enhanced autophagic activity rather than flux inhibition. Furthermore, Tdpep treatment significantly reduced cellular ROS levels, indicating effective autophagic turnover. Apoptosis assays showed that Tdpep did not induce apoptosis, confirming its selective autophagy induction. Furthermore, Tdpep nanosystem also induced autophagy in Danio rerio larvae in vivo model. Thus, this targeted DNA tetrahedron nanosystem provides a precise autophagy modulation platform with minimized off-target effects, offering a promising therapeutic strategy for diseases associated with autophagy dysfunction. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=133 SRC="FIGDIR/small/621781v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@193cde5org.highwire.dtl.DTLVardef@b2a041org.highwire.dtl.DTLVardef@13711eaorg.highwire.dtl.DTLVardef@792bb5_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2024

Design of diverse, functional mitochondrial targeting sequences across eukaryotic organisms using variational autoencoder

Mitochondria play a key role in energy production and cellular metabolism, making them a promising target for metabolic engineering and disease treatment. However, despite the known influence of passenger proteins on localization efficiency, only a few protein-localization tags have been characterized for mitochondrial targeting. To address this limitation, we exploited Variational Autoencoder (VAE), an unsupervised deep learning framework, to design novel mitochondrial targeting sequences (MTSs). In silico analysis revealed that a high fraction of generated peptides are functional and possess features important for mitochondrial targeting. Additionally, we devised a sampling scheme to indirectly address biases arising from the differences in mitochondrial protein import machinery and characterized artificial MTSs in four eukaryotic organisms. These sequences displayed significant diversity, sharing less than 60% sequence identity with MTSs in the UniProt database. Moreover, we trained a separate VAE and employed latent space interpolation to design dual targeting sequences capable of targeting both mitochondria and chloroplasts, shedding light on their evolutionary origins. As a proof-of-concept, we demonstrate the application of these artificial MTSs in increasing titers of 3-hydroxypropionic acid through pathway compartmentalization and improving 5-aminolevulinate synthase delivery by 1.62-fold and 4.76-fold, respectively. Overall, our work not only demonstrates the potential of generative artificial intelligence in designing novel, functional mitochondrial targeting sequences but also highlights their utility in engineering mitochondria for both fundamental research and practical applications in biology.

synthetic biology↗

bioRxiv2024

Imaging-Guided Metabolic Radiosensitization of Pediatric Rhabdoid Tumors

Tumor hypoxia leads to radioresistance and markedly worse clinical outcomes for pediatric malignant rhabdoid tumors (MRT). Our transcriptomics and bioenergetic profiling data reveal that mitochondrial oxidative phosphorylation (OXPHOS) is a metabolic vulnerability of MRT and can be exploited to overcome consumptive hypoxia by repurposing an FDA-approved anti-malarial drug, Atovaquone (AVO). We then establish the utility of Oxygen-Enhanced-Multispectral Optoacoustic Tomography (OE-MSOT), a label-free, ionizing radiation-free imaging modality, to visualize and quantify spatiotemporal changes in tumor hypoxia in response to AVO. We show a potent but transient increase in tumor oxygenation upon AVO treatment which results in complete elimination of tumors in all tested mice when combined with 10 Gy radiotherapy, a dose several times lower than the current clinic standard. Finally, we use translational mathematical modeling for systematic evaluation of dosing regimens, administration timing, and therapeutic synergy in a virtual clinical patient population. Together, our work establishes a framework for safe and pediatric patient-friendly image-guided metabolic radiosensitization of rhabdoid tumors.

bioengineering↗

bioRxiv2024

Sleep and circadian rhythm activity alterations during adolescence in a mouse model of neonatal fentanyl withdrawal syndrome

PurposeFentanyl, a highly potent synthetic opioid, is a major contributor to the ongoing opioid epidemic. During adulthood, fentanyl is known to induce pronounced sleep and circadian disturbances during use and withdrawal. Children exposed to opioids in utero are likely to develop neonatal opioid withdrawal syndrome, and display sleep disturbances after birth. However, it is currently unknown how neonatal opioid withdrawal from fentanyl impacts sleep and circadian rhythms in mice later in life. MethodsTo model neonatal opioid withdrawal syndrome, mice were treated with fentanyl from postnatal days 1 through 14, analogous to the third trimester of human gestation. After weaning, fentanyl and saline treated mice underwent non-invasive sleep and circadian rhythm monitoring during adolescence postnatal days 23 through 30. ResultsNeonatal fentanyl exposure led to reduced duration of wake and a decrease in the number of bouts of non-rapid eye movement sleep. Further, neonatally exposed mice displayed an increase in the average duration of rapid eye movement sleep bouts, reflecting an overall increase in the percent time spent in rapid eye movement sleep across days. ConclusionsNeonatal fentanyl exposure leads to altered sleep-wake states during adolescence in mice.

neuroscience↗

bioRxiv2024

MYB transcription factor, NtMYB308, regulates anthocyanin and lignin content, and fungal tolerance in tobacco

Anthocyanins are secondary metabolites synthesized through the phenylpropanoid pathway. They attract pollinators, possess antioxidant properties that scavenge free radicals during environmental stress, and provide protection against various stress conditions. Lignin, another secondary metabolite, plays crucial roles in providing mechanical support, facilitating water and solute transport, and protecting against pathogens. MYB transcription factors, particularly R2R3 MYBs, are key regulators of secondary metabolism, especially within the phenylpropanoid pathway. These factors act as both activators and repressors. The N-terminal region of R2R3-MYB repressors contains a conserved bHLH-binding domain, while the C-terminal domain is divergent and includes an EAR repressor domain. R2R3-MYB proteins notably target sequences such as the MYB-response element and AC elements. In this study, we identified and characterized the Nicotiana MYB transcription factor, NtMYB308, and explored its regulatory function in anthocyanin and lignin biosynthesis in tobacco. Our Virus Induced Gene Silencing (VIGS) and Protein-DNA interaction studies suggest that NtMYB308 is a negative regulator of anthocyanin and lignin biosynthesis by binding to the promoters of genes involved in these pathways. To validate our findings, we developed CRISPR/Cas9-based knockout mutant plants of tobacco, NtMYB308CR, which showed up-regulation of anthocyanin and lignin biosynthesis. Conversely, NtMYB308 overexpression (NtMYB308OX) plants exhibited the opposite effect. Enhanced anthocyanin and lignin levels in NtMYB308CR plants provided tolerance against the fungus Alternaria solani, while NtMYB308OX lines were susceptible. This study advances our understanding of the regulatory mechanisms governing anthocyanin and lignin biosynthesis and their role in biotic stress in tobacco. One Sentence SummaryA R2R3 MYB transcription factor, NtMYB308, negatively regulates anthocyanin and lignin content, and fungal tolerance in tobacco.

plant biology↗

bioRxiv2024

More is better: A simple antibody-based strategy for recovering all major mouse brain cell types from multiplexed single-cell RNAseq samples.

Single-cell RNA sequencing (scRNAseq) is a powerful yet costly technique for studying cellular diversity within the complexity of organs and tissues. Here, we sought to establish an effective multiplexing strategy for the adult mouse brain that could allow multiple experimental groups to be pooled into a single sample for sequencing, reducing costs, increasing data yield, and eliminating batch effects. We first describe an optimized cold temperature single-cell dissociation protocol that permits isolation of a high yield and viability of brain cells from the adult mouse. Cells isolated using this protocol were then screened by flow cytometry using a panel of antibodies, allowing identification of a single antibody, anti-Thy1.2, that can tag the vast majority of isolated mouse brain cells. We then used this primary antibody against a "universal" neural target, together with secondary antibodies carrying sample-specific oligonucleotides and the BD Rhapsody single-cell system and show that multiple adult mouse brain samples can be pooled into a single multiplexed run for scRNAseq. Bioinformatic analyses enable efficient demultiplexing of the sequenced pooled brain sample, with high tagging efficiency and precise annotation and clustering of brain cell populations. The efficiency and flexibility of the cell dissociation protocol and the two-step multiplexing strategy simplifies experimental design, optimizes reagent usage, eliminates sequencing batch effects and reduces overall experimental costs.

molecular biology↗

bioRxiv2024

Programmable soft DNA hydrogels stimulate cellular endocytic pathways and proliferation

Hydrogels are pivotal in tissue engineering, regenerative medicine, and drug delivery applications. DNA molecules stand out among various biomaterials due to their unparalleled precision, programmability, and customization. In this study, we introduce a palate of novel cellular scaffolding platforms made of pure DNA-based hydrogel systems while improving the shortcomings of the existing platforms. DNA strands can form complex supramolecular branched structures essential for designing novel functional materials by its precise sequence-based self-assembly. These unique geometric scaffolds offer a soft, cushiony platform, ideal for culturing cells to mimic the complex native in vivo environments better. Each hydrogel comprises repeating units of branched DNA supramolecular structures, each possessing a distinct number of branching arms. The epithelial cells grown over these hydrogels show dynamic changes at multiple levels, from morphology to protein expression patterns, enhanced membrane traffic, and proliferation. The DNA hydrogels explored here are mechanically weak and soft and thus appropriate for applications in cell biology. This research lays the groundwork for developing a DNA hydrogel system with a higher dynamic range of stiffness, which will open exciting avenues for tissue engineering and beyond. Graphical abstract illustrating diverse branched DNA supramolecular architectures forming DNA hydrogels of various geometric profiles, each put to use in the cell culture applications. O_FIG O_LINKSMALLFIG WIDTH=160 HEIGHT=200 SRC="FIGDIR/small/595930v1_ufig1.gif" ALT="Figure 1"> View larger version (41K): org.highwire.dtl.DTLVardef@1a3d4cborg.highwire.dtl.DTLVardef@e771cforg.highwire.dtl.DTLVardef@e0d5b4org.highwire.dtl.DTLVardef@ee42d3_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2024

The contribution of small protected areas to the big picture of forest conservation and restoration in Sweden

In forest regions worldwide, industrial forestry has left fragments of natural forests behind. This challenges biodiversity conservation and calls for ecological restoration for sustainable forest management and conservation. The functionality of protected areas need to be improved and forest ecosystems set in a state that better favors biodiversity, resilience and provisioning of ecosystem services. Sweden contributes a substantial share of the European forests, with dominance of non-industrial forest ownership and extensive forestry footprint, and hence with immediate need for advanced conservation and restoration. Protection through voluntary nature conservation agreements and regulated biotope protection areas exists since the 1990s, with schemes involving economic compensation to landowners to facilitate conservation and restoration. Across entire Sweden and all ecoregions, we assessed their accumulated capacity over a 30-year period, including forest types protected, type of restoration management, rotation intervals, and selection of tree species. These nearly 14,000 different areas covering over 70,000ha are small, ranging in size from 5ha but rarely larger than 20ha. Their contribution is important, particularly in south Sweden with low and fragmented forest cover among many different owners. Active restoration dominates over passive set asides, coniferous forest types are less represented than more rare forest types, many different tree species are favored, and different restoration types occur but with few types dominating. In recognizing their critical importance, we find that the practices are narrow and repetitive, and that a greater restoration diversification is needed. The decreasing trend in protection is alarming since these contribute key forest type representativeness and functionality.

ecology↗

bioRxiv2024

Self-assembled DNA-collagen bioactive scaffolds promote cellular uptake and neuronal differentiation

Different modalities of DNA-Collagen complexes have been utilized primarily for gene delivery studies. However, very few studies have investigated the potential of these complexes as bioactive scaffolds. Further, no studies have characterized the DNA-Collagen complex formed from the interaction of self-assembled DNA macrostructure and collagen. Towards this investigation, we report herein the fabrication of novel bioactive scaffolds formed from the interaction of sequence-specific, self-assembled DNA macrostructure and collagen type I. Varying molar ratios of DNA and collagen resulted in highly intertwined fibrous scaffolds with different fibrillar thicknesses. The formed scaffolds were biocompatible and presented as a soft matrix for cellular growth and proliferation. Cells cultured on DNA/Collagen scaffolds promoted enhanced cellular uptake of transferrin, and the potential of DNA/Collagen scaffolds to induce neuronal cell differentiation was further investigated. The DNA/Collagen scaffolds promoted neuronal differentiation of precursor cells with extensive neurite growth in comparison to control groups. These novel, self-assembled DNA/Collagen scaffolds could serve as a platform for the development of various bioactive scaffolds with potential applications in neuroscience, drug delivery, tissue engineering, and in vitro cell culture. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=137 HEIGHT=200 SRC="FIGDIR/small/595848v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@26e16aorg.highwire.dtl.DTLVardef@991d35org.highwire.dtl.DTLVardef@4c8909org.highwire.dtl.DTLVardef@b8ba55_HPS_FORMAT_FIGEXP M_FIG C_FIG

bioengineering↗

bioRxiv2024

Antigen-driven expansion of public clonal T cell populations in inflammatory bowel diseases

BackgroundInflammatory Bowel Diseases (IBDs), including Crohns disease (CD) and ulcerative colitis (UC), are known to involve shifts in the T-cell repertoires of affected individuals. These include a reduction in regulatory T cells in both diseases, increase in TNF production in CD, expansion of an unconventional T-cell population in CD, and clonal expansion of abundant T-cell populations in CD mucosal tissue. There are also differential HLA risk and protective alleles between CD and UC, implying CD- and UC-specific repertoire changes that have not yet been identified. MethodsWe performed ImmunoSequencing on blood samples from 3,853 CD cases, 1,803 UC cases, and 5,596 healthy controls. For each sample we imputed HLA type and cytomegalovirus (CMV) infection status based on public T-cell receptor {beta} (TCRB) usage and identified public TCRBs enriched in CD or UC cases. FindingsWe determine that there is more expansion across clonotypes in CD, but not UC, compared with healthy controls. We also identify novel interactive effects of HLA-DQ heterodimers with CD and UC risk. Strikingly, from blood we identify public TCRBs specifically expanded in CD or UC. These sequences are more abundant in intestinal mucosal samples, form groups of similar CDR3 sequences, and can be associated to specific HLA alleles. Although the prevalence of these sequences is higher in ileal and ileocolonic CD than colonic CD or UC, the TCRB sequences themselves are shared across CD and not between CD and UC. InterpretationThere are peptide antigens that commonly evoke immune reactions in IBD cases and rarely in non-IBD controls. These antigens differ between CD and UC. CD, particularly ileal CD, also seems to involve more substantial changes in clonal population structure than UC, compared to healthy controls.

immunology↗

bioRxiv2024

IB-DNQ and Rucaparib dual treatment alters cell cycle regulation and DNA repair in triple negative breast cancer cells

Triple negative breast cancer (TNBC) is a highly aggressive breast cancer that is unresponsive to hormonal therapies. One potential TNBC-specific therapeutic target is NQO1, as it is highly expressed in many TNBC patients and lowly expressed in non-cancer tissues. Here we use a derivative of DNQ, isobutyl-deoxynyboquinone (IB-DNQ) that is more potent and specific in killing TNBC cells than NQO1-activator {beta}-lapachone while displaying strong NQO1-dependence. We evaluated the cellular signaling changes that occur following 4-hour treatment of TNBC cells with either single agent or combination IB-DNQ and / or PARP inhibitor (Rucaparib). Short treatments (4 hours) with IB-DNQ alone or combined with the PARP inhibitor Rucaparib revealed few changes in protein abundance but significant rapid alterations in protein phosphorylation and thermal stability, with clear synergy in the combination treatment. Key phosphorylated targets linked to RNA Polymerase II inhibition and DNA damage response were altered during our short time treatment. Thermal proteome profiling (TPP) identified novel, combination-specific changes in protein biophysical state suggesting new therapeutic vulnerabilities in TNBC cells. Our findings highlight how even brief treatments can uncover distinct biophysical protein changes via TPP, offering a resource for mechanistic studies of IB-DNQ mechanism of action and the development of NQO1-activated therapeutics for TNBC treatment.

cancer biology↗

bioRxiv2024

T2R14 mediated antimicrobial responses through interactions with CFTR

Bitter taste receptors (T2Rs), are a subset of G protein-coupled receptors (GPCRs) that play a key role in responding to microbial presence at epithelial surfaces. In epithelia, the activities of ion channels and transporters, and of T2Rs, mutually affect each other. The normal function of one such anion channel, cystic fibrosis transmembrane conductance regulator (CFTR), is essential for the maintenance of healthy epithelia, not just in the respiratory but in the digestive and reproductive system as well. Based on evidence that T2R14 activity is affected upon mutations in CFTR, we explored the possibility that T2R14 and CFTR directly interact in cell membranes. The biophysical interaction between these proteins was mapped to specific regions of the CFTR, and was dependent on agonist stimulation of T2R14. Further, T2R14 was found to couple to Gq, in addition to the canonical Gi, in response to bacterial and fungal quorum sensing molecules. Whether the interaction with CFTR affects T2R14 driven responses to microbial signals is under investigation.

biochemistry↗

bioRxiv2024

The genomic trajectory of ovarian high grade serous carcinoma is determined in STIC lesions

Ovarian high-grade serous carcinoma (HGSC) originates in the fallopian tube, with secretory cells carrying a TP53 mutation, known as p53 signatures, identified as potential precursors. p53 signatures evolve into serous tubal intraepithelial carcinomas (STIC) lesions, which, in turn, progress into invasive HGSC that readily spread to the ovary and disseminate around the peritoneal cavity. We recently investigated the genomic landscape of early- and late-stage HGSC and found higher ploidy in late-stage (median 3.1) than early-stage (median 2.0) samples. Here, to explore whether the high ploidy and possible whole genome duplication observed in late-stage disease are determined early in the evolution of HGSC, we analysed archival formalin-fixed paraffin-embedded samples (FFPE) from five HGSC patients. p53 signatures and STIC lesions were laser-capture microdissected and sequenced using shallow whole genome sequencing (sWGS), while invasive ovarian/fallopian tube and metastatic carcinoma samples underwent macrodissection and were profiled using both sWGS and targeted next generation sequencing. Results showed highly similar patterns of global copy number change between STIC lesions and invasive carcinoma samples within each patient. Ploidy changes were evident in STIC lesions, but not p53 signatures, and there was strong correlation between ploidy in STIC lesions and invasive ovarian/fallopian tube and metastatic samples in each patient. The reconstruction of sample phylogeny for each patient from relative copy number indicated that high ploidy, when present, occurred early in the evolution of HGSC, which was further validated by copy number signatures in ovarian and metastatic tumours. These findings suggest that aberrant ploidy, suggestive of whole genome duplication, arises early in HGSC, and is detected in STIC lesions, implying that the trajectory of HGSC may be determined at the earliest stages of tumour development.

cancer biology↗

bioRxiv2024

HY5 and COP1 function antagonistically in the light-dependent regulation of nicotine biosynthesis in tobacco

Nicotine constitutes approximately 90% of the total alkaloid content within the Nicotiana species, rendering it the most prevalent alkaloid. While the majority of genes responsible for nicotine biosynthesis express in root tissue, the influence of light on this process through shoot-to-root mobile ELONGATED HYPOCOTYL 5 (HY5) has been recognized. CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1), a key regulator of light-associated responses, known for its role in modulating HY5 accumulation, remains largely unexplored in its relationship to light-dependent nicotine accumulation. Here, we identified NtCOP1, a COP1 homolog in Nicotiana tabacum, and demonstrated its ability to complement the cop1 mutant in Arabidopsis thaliana at molecular, morphological, and biochemical levels. Through the development of NtCOP1 overexpression (NtCOP1OX) plants, we observed a significant reduction in nicotine and flavonol content, inversely correlated with the down-regulation of nicotine and phenylpropanoid pathway. Conversely, CRISPR/Cas9-based knockout mutant plants (NtCOP1CR) exhibited an increase in nicotine levels. Further investigations, including yeast-two hybrid assays, grafting experiments, and western blot analyses, revealed that NtCOP1 modulates nicotine biosynthesis by targeting NtHY5, thereby impeding its transport from shoot-to-root. We conclude that the interplay between HY5 and COP1 functions antagonistically in the light-dependent regulation of nicotine biosynthesis in tobacco. HighlightCharacterization of CONSTITUTIVE PHOTOMORPHOGENIC1 (COP1) overexpressing and CRISPR/Cas9-based mutant plants suggests the intricate role of COP1 in modulating nicotine biosynthesis in tobacco.

plant biology↗

bioRxiv2024

Rational protein engineering to enhance MHC-independent T cell receptors

Chimeric antigen receptor (CAR)-based therapies have pioneered synthetic cellular immunity against cancer, however remain limited in their scope and long-term efficacy. Emerging data suggest that dysregulated CAR-driven T cell activation causes T cell dysfunction and therapeutic failure. To re-engage the endogenous T cell response, we designed hybrid MHC-independent T cell receptors (miTCRs) by linking antibody variable domains to TCR constant domains. While functional, we observed stark differences in miTCR-driven T cell function that were dependent on receptor orientation. Using predictive structural modeling, we observed significant biochemical conflicts at the hybrid variable-constant domain interface. To overcome this, we performed iterative sequence modifications and structural modeling to design a panel of miTCR variants predicted to have improved interface stability. Functional screening nominated a variant with superior efficacy to all other miTCRs as well as a standard CAR against high burdens of leukemia. Statement of SignificanceImproving the durability of engineered T cell immunotherapies is critical to enhancing efficacy. We used structure-informed design to evolve MHC-independent T cell receptors that drive improved tumor control. This work underscores the central role of synthetic receptor structure on T cell function and provides a framework for improved receptor engineering.

immunology↗

bioRxiv2024

Characterization Of Bitter Taste Receptor Dependent Autophagy in Oral Epithelial Cells

Microbial dysbiosis is an important trigger in the development of oral diseases. Oral keratinocytes or gingival epithelial cells (GECs) offer protection against various microbial insults. Recent studies suggest GECs expressed higher level of bitter taste receptor 14 (T2R14) compared to other taste receptors and toll-like receptors and acts as innate immune sentinels. Macroautophagy or autophagy is a cellular conserved process involved in the regulation of host innate immune responses against microbial infection. Here, we describe a robust method for evaluation of T2R14-dependent autophagy flux in GECs. Autophagy flux was detected using western blot analysis in GECs and further was confirmed using Acridine Orange dependent flow cytometry analysis. Workflow O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=151 SRC="FIGDIR/small/578576v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@1fa7b46org.highwire.dtl.DTLVardef@1b333baorg.highwire.dtl.DTLVardef@939d5org.highwire.dtl.DTLVardef@1b3f6f9_HPS_FORMAT_FIGEXP M_FIG C_FIG Graphical abstractSchematic showing the methodology (Western blot and flow cytometry) used for assessment of autophagy flux in GEC (created with Biorender). GEC: Gingival epithelial cells, BafA1: Bafilomycin, Rapa: Rapamycin, LC3-II: microtubule associated light chain protein, p62: sequestosome 1

cell biology↗