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Li, C.

Publications and source records attributed to Li, C..

At least 541 records · Page 30Linked to original sources

scDirect: key transcription factor identification for directing cell state transitions based on single-cell multi-omics data

Cell state transitions are complicated processes that occur in various life activities. Understanding and artificially manipulating them have been longstanding challenges. Substantial experiments reveal that the transitions could be directed by several key transcription factors (TFs). Here we present scDirect, a computational framework to identify key TFs based on single-cell RNA-seq and ATAC-seq data. scDirect models the TF identification task as a linear inverse problem, and solve it with gene regulatory networks enhanced by a graph attention network. Through a benchmarking on a single-cell human embryonic stem cell atlas, we demonstrate the robustness and superiority of scDirect against alternative analysis methods on TF identification. We apply scDirect on various datasets, and scDirect exhibits high capability in identifying key TFs in cell differentiation and somatic cell conversion. Furthermore, scDirect can efficiently identify TF combinations for cell reprogramming, many of which have been experimentally validated. We envision that scDirect can utilize rapidly increasing single-cell datasets to identify key TFs for directing cell state transitions and may become an effective tool to facilitate cell engineering and regenerative medicine.

bioinformatics↗

Surface colonization by Flavobacterium johnsoniae promotes its survival in a model microbial community

Flavobacterium johnsoniae is a ubiquitous soil and rhizosphere bacterium, but despite its abundance, the factors contributing to its success in communities are poorly understood. Using a model microbial community, The Hitchhikers Of the Rhizosphere (THOR), we determined the effects of colonization on fitness of F. johnsoniae in the community. Insertion sequencing (INSeq), a massively parallel transposon mutant screen, on sterile sand identified 25 genes likely to be important for surface colonization. We constructed in-frame deletions of nine candidate genes predicted to be involved in cell membrane biogenesis, motility, signal transduction, and transport of amino acids and lipids. All mutants poorly colonized sand, glass, and polystyrene and produced less biofilm than the wild type, indicating the importance of the targeted genes in surface colonization. Eight of the nine colonization-defective mutants were also unable to form motile biofilms, or zorbs, thereby suggesting that the affected genes play a role in group movement and linking stationary and motile biofilm formation genetically. Furthermore, we showed that deletion of colonization genes in F. johnsoniae affected its behavior and survival in THOR on surfaces, suggesting that the same traits are required for success in a multispecies microbial community. Our results provide insight into the mechanisms of surface colonization by F. johnsoniae and form the basis for further understanding its ecology in the rhizosphere. IMPORTANCEMicrobial communities direct key environmental processes through multispecies interactions. Understanding these interactions is vital for manipulating microbiomes to promote health in human, environmental, and agricultural systems. However, microbiome complexity can hinder our understanding of the underlying mechanisms in microbial community interactions. As a first step towards unraveling these interactions, we explored the role of surface colonization in microbial community interactions using THOR, a genetically tractable model community of three bacterial species, Flavobacterium johnsoniae, Pseudomonas koreensis, and Bacillus cereus. We identified F. johnsoniae genes important for surface colonization in solitary conditions and in the THOR community. Understanding the mechanisms that promote success of bacteria in microbial communities brings us closer to targeted manipulations to achieve outcomes that benefit agriculture, the environment, and human health.

microbiology↗

Targeting transcription factors through an IMiD independent zinc finger domain

Immunomodulatory imide drugs (IMiDs) degrade specific C2H2 zinc finger degrons in transcription factors, making them effective against certain cancers. SALL4, a cancer driver, contains seven C2H2 zinc fingers in four clusters, including an IMiD degron in zinc finger cluster two (ZFC2). Surprisingly, IMiDs do not inhibit growth of SALL4 expressing cancer cells. To overcome this limit, we focused on a non-IMiD degron, SALL4 zinc finger cluster four (ZFC4). By combining AlphaFold and the ZFC4-DNA crystal structure, we identified a potential ZFC4 drug pocket. Utilizing an in silico docking algorithm and cell viability assays, we screened chemical libraries and discovered SH6, which selectively targets SALL4-expressing cancer cells. Mechanistic studies revealed that SH6 degrades SALL4 protein through the CUL4A/CRBN pathway, while deletion of ZFC4 abolished this activity. Moreover, SH6 led to significant 62% tumor growth inhibition of SALL4+ xenografts in vivo and demonstrated good bioavailability in pharmacokinetic studies. In summary, these studies represent a new approach for IMiD independent drug discovery targeting C2H2 transcription factors in cancer. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=177 SRC="FIGDIR/small/574032v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@b8e4e8org.highwire.dtl.DTLVardef@bc6f01org.highwire.dtl.DTLVardef@11bbe85org.highwire.dtl.DTLVardef@791cb1_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

Integrated Analyses of Multi-omic Data Derived from Paired Primary Lung Cancer and Brain Metastasis Reveals the Metabolic Vulnerability as a Novel Therapeutic Target

Lung cancer brain metastases (LC-BrMs) are frequently associated with dismal mortality rates in patients with lung cancer; however, standard of care therapies for LC-BrMs are still limited in their efficacy. A deep understanding of molecular mechanisms and tumor microenvironment of LC-BrMs will provide us with new insights into developing novel therapeutics for treating patients with LC-BrMs. Here, we performed integrated analyses of genomic, transcriptomic, proteomic and metabolomic data which were derived from a total number of 174 patients with paired and unpaired primary lung cancer and LC-BrM, spanning four published and two newly generated patient cohorts on both bulk and single cell levels. We uncovered that LC-BrMs exhibited significantly higher intra-tumor heterogeneity. We also observed that mutations in a subset of genes were almost always shared by both primary lung cancers and LC-BrM lesions, including TTN, TP53, MUC16, LRP1B, RYR2, and EGFR. In addition, the genome-wide landscape of somatic copy number alterations was similar between primary lung cancers and LC-BrM lesions. Nevertheless, several regions of focal amplification were significantly enriched in LC-BrMs, including 5p15.33 and 20q13.33. Intriguingly, integrated analyses of transcriptomic, proteomic and metabolomic data revealed mitochondrial-specific metabolism was activated but tumor immune microenvironment was suppressed in LC-BrMs. Subsequently, we validated our results by conducting real-time quantitative reverse transcription PCR experiments, immunohistochemistry and multiplexed immunofluorescence staining of patients paired tumor specimens. Patients with a higher expression of mitochondrial metabolism genes but a lower expression of immune genes in their LC-BrM lesions tended to have a worse survival outcome. Therapeutically, targeting oxidative phosphorylation with gamitrinib in patient-derived organoids specific to LC-BrMs induced apoptosis and inhibited cell proliferation. The combination of gamitrinib plus anti-PD-1 immunotherapy significantly improved survival of mice bearing LC-BrMs. In conclusion, our findings not only provide comprehensive and integrated perspectives of molecular underpinnings of LC-BrMs but also contribute to the development of a potential, rationale-based combinatorial therapeutic strategy with the goal of translating it into clinical trials for patients with LC-BrMs.

cancer biology↗

MERITS: a web-based integrated MycobacterialPE/PPE protein database

MotivationPE/PPE proteins, highly abundant in the Mycobacterium genome, play a vital role in virulence and immune modulation. Understanding their functions is key to comprehending the internal mechanisms of Mycobacterium. However, a lack of dedicated resources has limited research into PE/PPE proteins. ResultsAddressing this gap, we introduce MERITS, a comprehensive 3D structure database specifically designed for PE/PPE proteins. MERITS hosts 22,353 non-redundant PE/PPE proteins, encompassing details like physicochemical properties, subcellular localisation, post-translational modification sites, protein functions, and measures of antigenicity, toxicity, and allergenicity. MERITS also includes data on their secondary and tertiary structure, along with other relevant biological information. MERITS is designed to be user-friendly, offering interactive search and data browsing Features to aid researchers in exploring the potential functions of PE/PPE proteins. MERITS is expected to become a crucial resource in the field, aiding in developing new diagnostics and vaccines by elucidating the sequence-structure-functional relationships of PE/PPE proteins. Availability and implementationMERITS is freely accessible at http://merits.unimelb-biotools.cloud.edu.au/.

bioinformatics↗

Glucocorticoids rapidly modulate CaV1.2-mediated calcium signals through Kv2.1 channel clusters in hippocampal neurons

The precise regulation of Ca2+ signals plays a crucial role in the physiological functions of neurons. Here, we investigated the rapid effect of glucocorticoids on Ca2+ signals in hippocampal neurons. In cultured hippocampal neurons, glucocorticoids inhibited the spontaneous somatic Ca2+ spikes generated by Kv2.1-organized Ca2+ microdomains. Furthermore, glucocorticoids rapidly reduced the cell surface expressions of Kv2.1 and CaV1.2 channels in hippocampal neurons. In HEK293 cells transfected with Kv2.1 alone, glucocorticoids significantly reduced the surface expression of Kv2.1 with little effect on K+ currents. Glucocorticoids inhibited CaV1.2 currents but had no effect on the cell surface expression of CaV1.2 in HEK293 cells transfected with CaV1.2 alone. Notably, in the presence of wild-type Kv2.1, glucocorticoids caused a decrease in the surface expression of CaV1.2 channels in HEK293 cells. However, this effect was not observed in the presence of non-clustering Kv2.1S586A mutant channels. Live cell imaging showed that glucocorticoids rapidly decreased Kv2.1 clusters on the plasma membrane. Correspondingly, western blot results indicated a significant increase in the cytoplasmic level of Kv2.1, suggesting the endocytosis of Kv2.1 clusters. Glucocorticoids rapidly decreased the intracellular cAMP concentration and the phosphorylation level of PKA in hippocampal neurons. The PKA inhibitor H89 mimicked the effect of glucocorticoids on Kv2.1, while the PKA agonist forskolin abrogated the effect. In conclusion, glucocorticoids rapidly regulate CaV1.2-mediated Ca2+ signals in hippocampal neurons by promoting the endocytosis of Kv2.1 channel clusters through reducing PKA activity. Significance StatementThe rapid non-genomic effect of glucocorticoids on the central nervous system is not fully understood. CaV1.2-mediated Ca2+ signaling microdomains control somatic Ca2+ signals and regulate excitation-transcription coupling in hippocampal neurons. Here, we demonstrate that glucocorticoids rapidly inhibit CaV1.2-mediated somatic Ca2+ spikes in hippocampal neurons. Glucocorticoids reduce the surface expression of Kv2.1 clusters but do not affect the surface expression of non-clustering Kv2.1. Moreover, glucocorticoids induce the endocytosis of CaV1.2 channels through wild-type Kv2.1. However, glucocorticoids cannot induce the endocytosis of CaV1.2 channels through Kv2.1S586A mutant channels, which cannot form clusters. This study sheds light on the intricate interplay between glucocorticoids, Kv2.1 channels, and CaV1.2 channels, unraveling a dual mechanism that influences both overall Ca2+ signaling and the intricate organization of neural microdomains.

neuroscience↗

DNA sensor ABCF1 phase separates with cccDNA to inhibit HBV replication

Objectives: Hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) contributes to viral persistence and recurrence. However, it is still less known how the host immune system responds to cccDNA and suppresses HBV replication. Therefore, it is essential to explore host proteins that interact with cccDNA and efficiently suppress HBV replication. Design: The interaction of cccDNA and ABCF1 was assessed by ChIP and pull-down assay. HBV replication was assessed in different cell models, including cccDNA surrogate-transfected and HBV-infected hepatocytes models. Phase separation of recombinant ABCF1 fusion proteins with cccDNA was observed by fluorescence microscopy. Results: Our data found that ABCF1 interacts with cccDNA to form phase-separated condensates via the poly-glutamine (PolyQ) of N-terminal intrinsically disordered low-complexity domain (LCD). Subsequently, ABCF1-cccDNA phase separation not only activates the type I/III interferon (IFN-I/III) pathway but also prevents Pol II accumulation on cccDNA to inhibit HBV transcription. Conclusions: Taken together, our study showed that ABCF1 acts as an antiviral restriction factor of HBV cccDNA by phase-separation-driven innate immune signaling and transcription inhibition. These findings shed new light on the understanding of host defense against cccDNA and provide a novel promising therapeutic strategy for HBV infection.

microbiology↗

Senolytics enhance longevity in Caenorhabditis elegans by altering betaine metabolism

Aging triggers physiological changes in organisms, which are tightly interlinked to metabolic changes. Senolytics are being developed. However, metabolic responses to natural senescence and the molecular intricacies of how senolytics confer antiaging benefits remain enigmatic. We performed a metabolomics study on natural senescence based on the C.elegans model. The results suggest that age-dependent metabolic changes of natural aging occur in C. elegans. Betaine was identified as a crucial metabolite in the natural aging process. To explore the common pathway coregulated by different senolytics prolonging nematodes lifespan, we fed nematodes three antiaging drugs metformin, quercetin, and minocycline. Our data show that the coregulated metabolic pathways associated with aging include the forkhead box transcription factor (FoxO), p38-mitogen-activated protein kinase (MAPK) and the target of rapamycin (mTOR) signaling pathway, etc. Three antiaging drugs raised betaine levels, consistent with high betaine levels in the younger nematode. Supplement of betaine prolonged the lifespan of nematodes via stimulating autophagy and improving antioxidant capacity. Altogether, our data support proof-of-concept evidence that betaine at appropriate concentrations can extend the lifespan of nematodes.

biochemistry↗

Dia2 formin controls receptor activity by organizing plasma membrane lipid partitioning at the nanoscale

Activation of JAK/STAT signaling by IFN-{gamma} requires partitioning of IFN-{gamma}R into specific lipid nanodomains at the plasma membrane. Using IFN-{gamma}R as a proxy, we investigated the role of actin dynamics in the formation and organization of lipid nanodomains, a process that remains poorly understood. We identified formin Dia2/DIAPH3 as a specific and RhoA -dependent regulator of IFN-{gamma}-induced JAK/STAT signaling. Based on lipidomics and specific probes enabling membrane lipid imaging by super resolution microscopy, we demonstrate that Dia2 is required for proper assembly of sphingomyelin and cholesterol lipid complexes. Finally, we show that the disorganization of lipid nanodomains induced by Dia2 depletion results in drastic changes in nano-partitioning and activity of other membrane proteins, such as Thy1 and PD-L1. Our data establish, therefore, the central role of the RhoA-Dia2 axis in the regulation of IFN-{gamma} induced JAK/STAT signaling, and more broadly, in the nanoscale organization of the plasma membrane.

cell biology↗

Function-associated scRNA-seq on single lung cancer organoids unravels the immune landscape of tumor parenchyma

In vitro models coupled with multimodal approaches are urgently needed to decipher the local tumor immune microenvironment (TIME) owing to the heterogeneous nature of immune cells and their diverse spatial distributions. Here we generate primary lung cancer organoids (pLCOs) by isolating the tumor cell clusters, including the infiltrated immune cells, from dissected lung cancer samples. A FascRNA-seq platform allowing both phenotypic evaluation and the scRNA-seq of all the single cells in an organoid was developed to dissect the TIME in individual pLCOs. Our analysis on 171 individual pLCOs derived from 7 patients revealed that pLCOs retained the fundamental features as well as intra-tumor heterogeneity of local TIME in the parenchyma of parental tumor tissues, providing a series of models with consistent genetic background but various TIME. Linking the single cell transcriptome data of individual pLCOs with their responses to ICB allowed us to confirm the pivotal role of CD8+ Ts in ICB induced anti-tumor immunity, to identify the potential tumor-reactive T cells with a set of 10 genes, and to unravel the factors regulating T cell activity.

cancer biology↗

Dissecting the Impact of Maternal Androgen Exposure on Offspring Health through Targeting the Androgen Receptor in Developmental Programming

Women with polycystic ovary syndrome (PCOS) exhibit sustained elevation in circulating androgens during pregnancy, an independent risk factor linked to pregnancy complications and adverse neonatal outcomes. Yet, further investigation is required to understand the precise mechanisms and the impact on cell-type specific placental dysfunction. To explore these dynamics, a PCOS-like mice model was induced with continuous androgen exposure throughout pregnancy, mimicking the human-PCOS. This resulted in impaired placental and embryonic development, leading to mid-gestation lethality. Co-treatment with the androgen receptor blocker, flutamide, prevented this lethality. Comprehensive analysis using whole-genome bisulfite and RNA sequencing revealed the diminished proportion of trophoblast precursors by downregulation of Cdx2. The absence of Gcm1, Synb, and Prl3b1 further resulted in decreased numbers of syncytiotrophoblasts and sinusoidal trophoblast giant cells, leading to observed compromised placenta labyrinth formation. Importantly, human trophoblast organoids exposed to androgens exhibited analogous alterations, highlighting impaired trophoblast differentiation as a key feature in PCOS-related pregnancy complications. Remarkably, all effects were mediated through the androgen receptor pathways, as demonstrated by comparable offspring phenotypes to controls when treated with flutamide. These findings provide novel insight into the PCOS-related pregnancy complications, and potential cellular targets for future treatment.

physiology↗

NS2B-D55E and NS2B-E65D Variations are Responsible for Differences in NS2B-NS3 Protease Activities Between Japanese Encephalitis Virus Genotype I and III in Fluorogenic Peptide Model

Japanese Encephalitis Virus (JEV) NS2B-NS3 is a protein complex composed of NS3 proteases and a NS2B cofactor. The N-terminal protease domain (180 residues) of NS3 (NS3(pro)) interacts directly with a central 40-amino acid hydrophilic domain of NS2B (NS2B(H)) to form an active serine protease. In this study, the recombinant NS2B(H)-NS3(pro) proteases were prepared in E. coli and used to compare the enzymatic activity between genotype I (GI) and III (GIII) NS2B-NS3 proteases. The GI NS2B(H)-NS3(pro) was able to cleave the sites at internal C, NS2A/NS2B, NS2B/NS3 and NS3/NS4A junctions that were identical to the sites proteolytically processed by GIII NS2B(H)-NS3(pro). Analysis of the enzymatic activity of recombinant NS2B(H)-NS3(pro) proteases using a model of fluorogenic peptide substrate revealed that the proteolytical processing activity of GIII NS2B(H)-NS3(pro) was significantly higher than that of GI NS2B(H)-NS3(pro). There were eight amino acid variations between GI and GIII NS2B(H)-NS3(pro), which may be responsible for the difference in enzymatic activities between GI and GIII proteases. Therefore, recombinant mutants were generated by exchanging NS2B(H) and NS3(pro) domains between GI and GIII NS2B(H)-NS3(pro) and subjected to protease activity analysis. Substitution of NS2B(H) significantly altered the protease activities, as compared to the parental NS2B(H)-NS3(pro), suggesting that NS2B(H) played an essential role in regulation of NS3(pro) protease activity. To further identify the amino acids responsible for the difference in protease activities, multiple substitution mutants including the individual and combined mutations at the variant residue 55 and 65 of NS2B(H) were generated and subjected to protease activity analysis. Replacement of NS2B-55 and NS2B-65 of GI to GIII significantly increased the enzymatic activity of GI NS2B(H)-NS3(pro) protease, whereas mutation of NS2B-55 and NS2B-65 of GIII to GI remarkably reduced the enzymatic activity of GIII NS2B(H)-NS3(pro) protease. Overall, these data demonstrated that NS2B-55 and NS2B-65 variations in hydrophilic domain of NS2B co-contributed to the difference in NS2B(H)-NS3(pro) protease activities between GI and GIII. These observations gain an insight into the role of NS2B in regulation of NS3 protease activities, which is useful for understanding the replication of JEV GI and GIII viruses.

microbiology↗

Deciphering the Cofilin Oligomers via Intermolecular Disulfide Bond Formation: A Coarse-grained Molecular Dynamics Approach to Understanding Cofilin's Regulation on Actin Filaments

Cofilin, a key actin-binding protein, orchestrates the dynamics of the actomyosin network through its actin-severing activity and by promoting the recycling of actin monomers. Recent experimental work suggests that cofilin also forms functionally distinct oligomers through thiol post-translational modification (PTM) that encourages actin nucleation and assembly. Despite these advances, the structural conformations of cofilin oligomers that modulate actin activity remain elusive because there are combinatorial ways to oxidize thiols in cysteines to form disulfide bonds rapidly. This study employs molecular dynamics simulations to investigate human cofilin 1 as a case study for exploring cofilin dimers via disulfide bond formation. Using the free energy profiling, our simulations unveil a range of probable cofilin dimer structures not represented in current Protein Data Bank entries. These candidate dimers are characterized by their distinct population distributions and relative free energies. Of particular note is a dimer featuring an interface between cysteines 139 and 147 residues, which demonstrates stable free energy characteristics and intriguingly symmetrical geometry. In contrast, the experimentally proposed dimer structure exhibits a less stable free energy profile. We also evaluate frustration quantification based on the energy landscape theory in the protein-protein interactions at the dimer interfaces. Notably, the 39-39 dimer configuration emerges as a promising candidate for forming cofilin tetramers, as substantiated by frustration analysis. Additionally, docking simulations with actin filaments further evaluate the stability of these cofilin dimer-actin complexes. Our findings thus offer a computational framework for understanding the role of thiol post-translational modification of cofilin proteins in regulating oligomerization, and the subsequent cofilin-mediated actin dynamics in the actomyosin network.

biophysics↗

CytoSimplex: Visualizing Single-cell Fates and Transitions on a Simplex

SummaryCells differentiate to their final fates along unique trajectories, often involving multi-potent progenitors that can produce multiple terminally differentiated cell types. Recent developments in single-cell transcriptomic and epigenomic measurement provide tremendous opportunities for mapping these trajectories. The visualization of single-cell data often relies on dimension reduction methods such as UMAP to simplify high-dimensional single-cell data down into an understandable two-dimensional (2D) form. However, these visualization methods can be misleading and often do not effectively represent the direction of cell differentiation. To address these limitations, we developed a new approach that places each cell from a single-cell dataset within a simplex whose vertices correspond to terminally differentiated cell types. Our approach can quantify and visualize current cell fate commitment and future cell potential. We developed CytoSimplex, a standalone open-source package implemented in R and Python that provides simple and intuitive visualizations of cell differentiation in 2D ternary and three-dimensional (3D) quaternary plots. We believe that CytoSimplex can help researchers gain a better understanding of cell type transitions in specific tissues and characterize developmental processes. Availability and implementationThe R version of CytoSimplex is available on Github at https://github.com/welch-lab/CytoSimplex. The Python version of CytoSimplex is available on Github at https://github.com/welch-lab/pyCytoSimplex.

bioinformatics↗

The ventral hippocampus and nucleus accumbens as neural substrates for cocaine contextual memory reconsolidation

Drug craving triggered by cues that were once associated with drug intoxication is a major contributor to continued drug-seeking behaviors. Addictive drugs engage molecular pathways of associative learning and memory. Reactivated memories are vulnerable to disruption by interference with the process of reconsolidation, hence targeting reconsolidation could be a strategy to reduce cue-induced drug craving and relapse. Here we examined the circuitry of cocaine contextual memory reconsolidation and explored neuroplasticity following memory reactivation. Mice underwent chemogenetic inhibition of either nucleus accumbens (NA) neurons or the glutamatergic projection neurons from the ventral hippocampus (vHPC) to NA using inhibitory designer receptors exclusively activated by designer drugs (iDREADD). Mice underwent cocaine conditioned place preference followed by reactivation of the cocaine contextual memory. Clozapine-N-oxide (CNO) was administered after memory reactivation to inhibit either NA neurons or the accumbens-projecting vHPC neurons during the reconsolidation period. When retested 3 days later, a significant reduction in the previously established preference for the cocaine context was found in both conditions. FosTRAP2-Ai14 mice were used to identify neurons activated by cocaine memory recall and to evaluate plasticity in NA medium spiny neurons (MSNs) and vHPC pyramidal neurons upon recall of cocaine memories. Results indicate a significant increase in dendritic spine density in NA MSNs activated by cocaine memory recall, particularly of the thin spine type. Sholl analysis indicated longer dendritic length and more branching of NA MSNs after cocaine memory recall than without memory reactivation. vHPC neurons showed increased spine density, with the most robust change in stubby spines. These results implicate a circuit involving glutamatergic projections from the vHPC onto NA neurons which is necessary for the reconsolidation of cocaine memories. Interruption of cocaine memory reconsolidation reduced drug-seeking behavior.

neuroscience↗

Enhancing Light-Sheet Fluorescence Microscopy Illumination Beams through Deep Design Optimization

Light sheet fluorescence microscopy (LSFM) provides the benefit of optical sectioning coupled with rapid acquisition times for imaging of tissue-cleared specimen. This allows for high-resolution 3D imaging of large tissue volumes. Inherently to LSFM, the quality of the imaging heavily relies on the characteristics of the illumination beam, with the notion that the illumination beam only illuminates a thin section that is being imaged. Therefore, substantial efforts are dedicated to identifying slender, non-diffracting beam profiles that can yield uniform and high-contrast images. An ongoing debate concerns the employment of the most optimal illumination beam; Gaussian, Bessel, Airy patterns and/or others. Comparisons among different beam profiles is challenging as their optimization objective is often different. Given that our large imaging datasets ([~]0.5TB images per sample) is already analyzed using deep learning models, we envisioned a different approach to this problem by hypothesizing that we can tailor the illumination beam to boost the deep learning models performance. We achieve this by integrating the physical LSFM illumination model after passing through a variable phase mask into the training of a cell detection network. Here we report that the joint optimization continuously updates the phase mask, improving the image quality for better cell detection. Our methods efficacy is demonstrated through both simulations and experiments, revealing substantial enhancements in imaging quality compared to traditional Gaussian light sheet. We offer valuable insights for designing microscopy systems through a computational approach that exhibits significant potential for advancing optics design that relies on deep learning models for analysis of imaging datasets.

scientific communication and education↗

Expansion of human hematopoietic stem cells by inhibiting translation

Hematopoietic stem cell (HSC) transplantation using umbilical cord blood (UCB) is a potentially life-saving treatment for leukemia and bone marrow failure but is limited by the low number of HSCs in UCB. The loss of HSCs after ex vivo manipulation is also a major obstacle to gene editing for inherited blood disorders. HSCs require a low rate of translation to maintain their capacity for self-renewal, but hematopoietic cytokines used to expand HSCs stimulate protein synthesis and impair long-term self-renewal. We previously described cytokine-free conditions that maintain but do not expand human and mouse HSCs ex vivo. Here we performed a high throughput screen and identified translation inhibitors that allow ex vivo expansion of human HSCs while minimizing cytokine exposure. Transplantation assays show a [~]5-fold expansion of long-term HSCs from UCB after one week of culture in low cytokine conditions. Single cell transcriptomic analysis demonstrates maintenance of HSCs expressing mediators of the unfolded protein stress response, further supporting the importance of regulated proteostasis in HSC maintenance and expansion. These culture conditions maintain adult HSCs after CRISPR/Cas9 editing of the BCL11A+58 enhancer, overcoming a major obstacle to ex vivo gene correction for human hemoglobinopathies. SignificanceO_LIWe report ex vivo expansion of human hematopoietic stem cells from umbilical cord blood using low cytokines and small molecule inhibitors of GSK-3, mTORC1, and the translation initiation factor eIF4E. C_LIO_LIOur method maintains human HSCs ex vivo after gene editing with conventional CRISPR/Cas9, lipid nanoparticle delivery, and base editing approaches, overcoming a major obstacle to gene editing for inherited blood disorders. C_LI

cell biology↗

Isolating neural signatures of conscious speech perception with a no-report sine-wave speechparadigm

Identifying neural correlates of conscious perception is a fundamental endeavor of cognitive neuroscience. Most studies so far have focused on visual awareness along with trial-by-trial reports of task relevant stimuli, which can confound neural measures of perceptual awareness with post-perceptual processing. Here, we used a three-phase sine-wave speech paradigm that dissociated between conscious speech perception and task relevance while recording EEG in humans of both sexes. Compared to tokens perceived as noise, physically identical sine-wave speech tokens that were perceived as speech elicited a left-lateralized, near-vertex negativity, which we interpret as a phonological version of a perceptual awareness negativity. This response appeared between 200 and 300 ms after token onset and was not present for frequency-flipped control tokens that were never perceived as speech. In contrast, the P3b elicited by task-irrelevant tokens did not significantly differ when the tokens were perceived as speech versus noise, and was only enhanced for tokens that were both perceived as speech and relevant to the task. Our results extend the findings from previous studies on visual awareness and speech perception, and suggest that correlates of conscious perception, across types of conscious content, are most likely to be found in mid-latency negative-going brain responses in content-specific sensory areas. Significance StatementHow patterns of brain activity give rise to conscious perception is a fundamental question of cognitive neuroscience. Here, we asked whether markers of conscious speech perception can be separated from task-related confounds. We combined sine-wave speech - a degraded speech signal that is heard as noise by naive individuals but can readily be heard as speech after minimal training - with a no-report paradigm that independently manipulated perception (speech versus non-speech) and task (relevant versus irrelevant). Using this paradigm, we were able to identify a marker of speech perception in mid-latency responses over left frontotemporal EEG channels that was independent of task. Our results demonstrate that the "perceptual awareness negativity" is present for a new type of perceptual content (speech).

neuroscience↗