Biology subjects

Tyler, M.

Publications and source records attributed to Tyler, M..

5 recordsLinked to original sources

bioRxiv2024

The Curated Cancer Cell Atlas: comprehensive characterisation of tumours at single-cell resolution

Single-cell RNA-seq (scRNA-seq) has transformed the study of cancer biology. Recent years have seen a rapid expansion in the number of single-cell cancer studies, yet most of these studies profiled few tumours, such that individual datasets have limited statistical power. Combining the data and results across studies holds great promise but also involves various challenges. We recently began to address these challenges by curating a large collection of cancer scRNA-seq datasets, and leveraging it for systematic analyses of tumor heterogeneity. Here we significantly extend this repository to 124 datasets for over 40 cancer types, together comprising 2,822 samples, with improved data annotations, visualisations and exploration. Utilising this vast cohort, we systematically quantified context-dependent gene expression and proliferation patterns across cell types and cancer types. These data, annotations and analysis results are all freely available for exploration and download via the Curated Cancer Cell Atlas (3CA) website (https://www.weizmann.ac.il/sites/3CA/), a central source of data and analyses for the cancer research community that opens new avenues in cancer research.

cancer biology↗

bioRxiv2024

Commensal-derived short-chain fatty acids disrupt lipid membrane homeostasis in Staphylococcus aureus

The role of commensal anaerobic bacteria in chronic respiratory infections is unclear, yet they can exist in abundances comparable to canonical pathogens in vivo. Their contributions to the metabolic landscape of the host environment may influence pathogen behavior by competing for nutrients and creating inhospitable conditions via toxic metabolites. Here, we reveal a mechanism by which the anaerobe-derived short chain fatty acids (SCFAs) propionate and butyrate negatively affect Staphylococcus aureus physiology by disrupting branched chain fatty acid (BCFA) metabolism. In turn, BCFA impairment results in impaired growth, diminished expression of the agr quorum sensing system, as well as increased sensitivity to membrane-targeting antimicrobials. Altered BCFA metabolism also reduces S. aureus fitness in competition with Pseudomonas aeruginosa, suggesting that airway microbiome composition and the metabolites they produce and exchange directly impact pathogen succession over time. The pleiotropic effects of these SCFAs on S. aureus fitness and their ubiquity as metabolites in animals also suggests that they may be effective as sensitizers to traditional antimicrobial agents when used in combination.

microbiology↗

bioRxiv2024

Subtypes and proliferation patterns of small intestine neuroendocrine tumors revealed by single cell RNA sequencing

Neuroendocrine tumors (NETs) occur primarily in the small intestine, lung and pancreas. Due to their rarity compared to other malignancies in these organs, their complex biology remains poorly understood, including their oncogenesis, tumor composition and the intriguing phenomena of mixed neuroendocrine non-neuroendocrine neoplasms (MiNEN). Here we profiled ten low-grade small intestine NET (SiNET) samples as well as one mixed lung tumor by single-cell or single-nuclei RNA-seq. We find that SiNETs are largely separated into two distinct subtypes, in which the neuroendocrine cells upregulate epithelial or neuronal markers, respectively. Surprisingly, in both subtypes the neuroendocrine cells are largely non-proliferative while higher proliferation is observed in multiple non-malignant cell types. Specifically, B and plasma cells are highly proliferative in the epithelial-like SiNET subtype, potentially reflecting the outcome of high Migration Inhibitory Factor (MIF) expression in those tumors, which may constitute a relevant target. Finally, our analysis of a mixed lung neuroendocrine tumor identifies a population of putative progenitor cells that may give rise to both neuroendocrine and non-neuroendocrine (squamous) cells, potentially explaining the origin of the mixed histology. Taken together, our results provide important insights and hypotheses regarding the biology of neuroendocrine neoplasms.

cancer biology↗

bioRxiv2021

The transcriptional hallmarks of intra-tumor heterogeneity across a thousand tumors

Each tumor contains malignant cells that differ in genotype, phenotype, and in their interactions with the tumor micro-environment (TME). This results in distinct integrated cellular states that govern intra-tumor heterogeneity (ITH), a central challenge of cancer therapeutics. Dozens of recent studies have begun to describe ITH by single cell RNA-seq, but each study typically profiledonly a small number of tumors and provided a narrow view of transcriptional ITH. Here, we curate, annotate and integrate the data from 77 different studies to reveal the patterns of ITH across 1,163 tumor samples covering 24 tumor types. Focusing on the malignant cells, we find thousands of transcriptional ITH programs that can be described by 41 consensus meta-programs (MPs), each consisting of dozens of genes that are coordinately upregulated in subpopulations of cells within many different tumors. The MPs cover diverse cellular processes and differ in their cancer-type distribution. General MPs associated with processes such as cell cycle and stress vary within most tumors, while context-specific MPs reflect the unique biology of particular cancer types, often resembling developmental cell types and suggesting the co-existence of variable differentiation states within tumors. Some of the MPs are further associated with overall tumor proliferation or immune state, highlighting their potential clinical significance. Based on functional similarities among MPs, we propose a set of 11 hallmarks that together account for the majority of observed ITH programs. Given the breadth and scope of the investigated cohort, the MPs and hallmarks described here reflect the first comprehensive pan-cancer description of transcriptional ITH.

cancer biology↗

bioRxiv2021

Phosphorylation-dependent control of Arc protein by synaptic plasticity regulator TNIK

Activity-regulated cytoskeleton-associated protein (Arc) is an immediate-early gene product that support neuroplastic changes important for cognitive function and memory formation. As a protein with homology to the retroviral Gag protein, a particular characteristic of Arc is its capacity to self-assemble into virus-like capsids that can package mRNAs and transfer those transcripts to other cells. Although a lot has been uncovered about the contributions of Arc to neuron biology and behavior, very little is known about how different functions of Arc are coordinately regulated both temporally and spatially in neurons. The answer to this question we hypothesized must involve the occurrence of different protein post-translational modifications acting to confer specificity. In this study, we used mass spectrometry and sequence prediction strategies to map novel Arc phosphorylation sites. Our approach led us to recognize serine 67 (S67) and threonine 278 (T278) as residues that can be modified by TNIK, which is a kinase abundantly expressed in neurons that shares many functional overlaps with Arc and has, along with its interacting proteins such as the NMDA receptor, been implicated as a risk factor for psychiatric disorders. Furthermore, characterization of each residue using site-directed mutagenesis to create S67 and T278 mutant variants revealed that TNIK action at those amino acids can strongly influence Arcs subcellular distribution and self-assembly as capsids. Together, our findings reveal an unsuspected connection between Arc and TNIK. Better understanding of the interplay between these two proteins in neuronal cells could lead to new insights about apparition and progression of psychiatric disorders.

neuroscience↗