Biology subjects

Cheung, G.

Publications and source records attributed to Cheung, G..

6 recordsLinked to original sources

bioRxiv2026

Lineage origin of spinal cord cell type diversity

The complexity and specificity of movement in vertebrates is driven by a rich diversity of spinal motor and interneuron cell types. During development, eleven spinal cord progenitor domains generate an equivalent number of cardinal neuron types. How progenitor domains, individual progenitors, and post-mitotic diversity relate is still unknown. We performed high-resolution, single-progenitor cell lineage tracing in the embryonic mouse spinal cord using mosaic analysis with double markers (MADM). Our quantitative study of lineage progression revealed that spinal cord progenitors undergo highly variable numbers of proliferative, neurogenic, and gliogenic cell divisions. The nascent clonally-related neurons migrate radially over large distances, span the dorsoventral axis, and even cross the midline, demonstrating striking bilaterality. Molecular and morphometric analysis indicate high levels of progenitor multipotency, with an individual progenitor capable of producing several molecularly and morphologically distinct neuron types, as well as astrocytes. These findings redefine spinal cord development as a process in which lineage variability--rather than rigid progenitor identity--drives the generation of cellular diversity.

neuroscience↗

bioRxiv2026

CAR T cell therapy selectively depletes disease-driving mutant calreticulin cells in xenotransplants and human organoid models of myelofibrosis

Targeted immunotherapies have revolutionized outcomes for lymphoid malignancies, but success in myeloid neoplasms is limited by the lack of amenable targets and immunologically hostile tumor microenvironment (TME). Myeloproliferative neoplasms are chronic myeloid blood cancers, a third of which are driven by mutations in calreticulin (mutCALR). This yields a common neoepitope that binds to, and activates, the thrombopoietin receptor and results in display of the oncoprotein on the extracellular membrane of disease-driving cells, exposing a therapeutic vulnerability. Here, we present a first-in-class chimeric antigen receptor (CAR) T-cell therapy that specifically targets mutCALR+ cells, both in vitro and in vivo. The CAR T-cell therapy selectively depleted mutCALR+ stem cells from patients with myelofibrosis while sparing healthy stem cells, and improved survival in mutCALR leukemia xenografts. To mimic myelofibrotic marrow, we developed a bespoke human chimeroid model and showed no decrease in the potency of CAR T cell-mediated target cell killing even in a fibrotic tumor microenvironment. We also devised a method to boost cell surface expression of mutCALR in CD34+ cells isolated from patients with accelerated/blast phase MPN (defined as >10 % blasts in peripheral blood or bone marrow), enhancing CAR T targeting. This study presents a therapeutic with potential to eradicate mutCALR-driven malignancies and highlights an innovative strategy to evaluate blood cancer-targeting immunotherapies in a relevant TME. One Sentence SummaryA first-in-class CAR T-cell therapy targeting mutant calreticulin selectively depletes malignant stem cells in vivo and in fibrotic human organoids.

cancer biology↗

bioRxiv2023

Multipotent Progenitors Instruct Ontogeny of the Superior Colliculus

The superior colliculus (SC) in the mammalian midbrain is essential for multisensory integration, attention, and complex behavior (Basso and May, 2017; Cang et al., 2018). The mature SC cytoarchitecture is organized into distinct laminae and composed of a rich variety of neuronal and glial cell types (Ayupe et al., 2023; Edwards et al., 1986; May, 2006; Xie et al., 2021; Zeisel et al., 2018). Precise execution of the developmental programs regulating the generation of SC cell-type diversity is essential, because deficits due to genetic mutations have been associated with neurodevelopmental diseases and SC dysfunction (Jure, 2018; McFadyen et al., 2020). However, the fundamentals directing the ontogeny of the SC are not well understood. Here we pursued systematic lineage tracing at the single progenitor cell level in order to decipher the principles instructing the generation of cell-type diversity in the SC. We combined in silico lineage reconstruction with a novel genetic MADM (Mosaic Analysis with Double Markers)-CloneSeq approach. MADM-CloneSeq enables the unequivocal delineation of cell lineages in situ, and cell identity based on global transcriptome, of individual clonally-related cells. Our systematic reconstructions of cell lineages revealed that all neuronal cell types in SC emerge from local progenitors without any extrinsic source. Strikingly, individual SC progenitors are exceptionally multipotent with the capacity to produce all known excitatory and inhibitory neuron types of the prospective mature SC, with individual clonal units showing no pre-defined composition. At the molecular level we identified an essential role for PTEN signaling in establishing appropriate proportions of specific inhibitory and excitatory neuron types. Collectively, our findings demonstrate that individual multipotent progenitors generate the full spectrum of excitatory and inhibitory neuron types in the developing SC, providing a novel framework for the emergence of cell-type diversity and thus the ontogeny of the mammalian SC.

neuroscience↗

bioRxiv2020

Physiological synaptic activity and recognition memory are fueled by astroglial glutamine

Presynaptic glutamate replenishment is fundamental to brain function. In high activity regimes, such as epileptic episodes, this process is thought to rely on the glutamate-glutamine cycle between neurons and astrocytes. However the presence of an astroglial glutamine supply, as well as its functional relevance in vivo in the healthy brain remain controversial, partly due to a lack of tools that can directly examine glutamine transfer. Here, we generated a novel fluorescent probe that tracks glutamine in live cells, which provided direct visual evidence of an activity-dependent glutamine supply from astroglial networks to presynaptic structures under physiological conditions. This mobilization is mediated by connexin43, an astroglial protein with both gap-junction and hemichannel functions, and is essential for synaptic transmission and object recognition memory. Our findings uncover an indispensable recruitment of astroglial glutamine in physiological synaptic activity and memory via an unconventional pathway, thus providing an astrocyte basis for cognitive processes.

neuroscience↗

bioRxiv2020

Active synthesis of collagen (I) homotrimer and matrisomal proteins in Dupuytren's fibrosis

Dupuytrens disease is a common fibroproliferative disease of the palmar fascia of the hand with advanced cases treated surgically. Anti-tumour necrosis factor (TNF) injection has undergone phase 2 trials and may be effective in slowing early-stage disease progression. Here we sought to determine how new synthesis of type I collagen in Dupuytrens differs from normal palmar fascia samples and to analyse the role of TNF in aberrant collagen synthesis. Model non-fibrotic, but fibrous connective tissues, were used to analyse active type I collagen protein synthesis in development, ageing and degenerative disease, where it was restricted to early development and ruptured tissue. Dupuytrens tissue was shown to actively synthesise type I collagen, including abnormal type I collagen homotrimer. TNF- reduced COL1A2 gene expression only in the presence of serum in 2D cell culture and had opposing effects on collagen protein production in the presence or absence of serum. TNF- had only limited effects in 3D tendon-like constructs. Anti-TNF did not reduce type I collagen synthesis in 3D tendon-like constructs or prevent type I collagen homotrimer synthesis in Dupuytrens tissue. Hence, modulation of the TNF- pathway in Dupuytrens disease is unlikely to prevent the pathological collagen accumulation that is characteristic of fibrosis.

cell biology↗

bioRxiv2020

Local translation in perisynaptic astrocytic processes is specific and regulated by fear conditioning

Local translation is a conserved molecular mechanism conferring cells the ability to quickly respond to local stimuli. It not only permits cells with complex morphology to bypass somatic protein synthesis and transport, but also contributes locally to the establishment of molecular and functional polarity. In the brain, local translation has been extensively studied in neurons and has only been recently reported in astrocytes, whose fine processes contact both blood vessels and synapses. Yet the specificity and regulation of astrocyte local translation remain unknown. Here, we studied hippocampal perisynaptic astrocytic processes (PAPs) and show that they contain all the machinery for translation. Using our recently refined polysome immunoprecipitation technique, we then characterized the pool of polysomal mRNAs in PAPs, referred to as the PAPome, and compared it to the one found in the whole astrocyte. We found that the PAPome encoded an unexpected molecular repertoire, mostly composed of cytoplasmic proteins and of proteins involved in iron homeostasis, translation, cell cycle and cytoskeleton. Among them, ezrin (Ezr), ferritin heavy chain 1 (Fth1) and 60S acidic ribosomal protein1 (Rplp1) were enriched in PAPs compared to perivascular astrocytic processes, indicating that local translation differs at these two interfaces. Remarkably, PAPs were also enriched in transcripts coding for proteins involved in learning and memory, such as ferritin (Ftl1 and Fth1), G1/S-specific cyclin-D2 (Ccnd2), E3 ubiquitin-protein ligase (Mdm2), Receptor of activated protein C kinase 1 (Gnb2l1) and Elongation factor 1-alpha 1 (Eef1a1). To address their regulation in a physiological context, we assessed their local translation after fear conditioning. We found alterations in their density and/or distribution in astrocytes as well as a drop in their translation specifically in PAPs. In all, our results reveal an unexpected molecular repertoire of hippocampal PAPs, which is regulated by local translation during learning and memory processes.

neuroscience↗