Biology subjects

Ma, F.

Publications and source records attributed to Ma, F..

At least 55 records · Page 3Linked to original sources

bioRxiv2023

Cholesterol-associated Locus EHBP1 Protects against NASH Fibrosis

SUMMARYHepatic free cholesterol contributes to fibrosis in nonalcoholic steatohepatitis (NASH), but how hepatic cholesterol metabolism becomes dysregulated in NASH is not completely understood. We show here that human fibrotic NASH livers have decreased EHBP1, a novel GWAS locus associated with LDL-cholesterol, and that the EHBP1 rs10496099 T>C variant in NASH patients is associated with decreased hepatic EHBP1 expression and augmented NASH fibrosis. Congruent with the human data, EHBP1 loss- and gain-of-function increases and decreases NASH fibrosis in mice, respectively. Mechanistic studies reveal that EHBP1 promotes sortilin (SORT1)-mediated PCSK9 secretion, leading to LDLR degradation, decreased LDL uptake, and reduced TAZ, a fibrogenic effector. Moreover, we show that the TNF/PPAR pathway suppresses EHBP1 in NASH. These data not only provide new mechanistic insight into the role of EHBP1 in cholesterol metabolism and NASH fibrosis by uncovering the interaction between EHBP1 and other cholesterol-related loci, including SORT1, PCSK9, and LDLR, but also elucidate a novel interplay between inflammation and EHBP1-mediated cholesterol metabolism. HighlightsHepatic EHBP1 is reduced in human and mouse fibrotic NASH EHBP1 rs10496099 T>C is associated with decreased hepatic EHBP1 and augmented NASH EHBP1 reduces LDLR, cholesterol uptake, and TAZ in hepatocytes EHBP1 promotes sortilin-mediated PCSK9 secretion in hepatocytes TNF suppresses EHBP1 expression in hepatocytes

pathology↗

bioRxiv2023

Spatiotemporal transcriptome atlas of human embryos after gastrulation

The spatial and temporal atlas of gene expression in the human embryo at early gestation is critical in understanding embryo development, organogenesis, and disease origins. We obtained the spatiotemporal transcriptome from 90 sagittal sections of 16 whole human embryos from 3 to 8 post-conception weeks by Stereo-seq with high resolution and ultra-large field, establishing the development trajectory/regulatory profiling of 49 organs. We uncovered the organ-specific regulons as potential lineage-determining factors and identified the new regulatory networks during heart and brain development. The atlas refines the key organs/cell types vulnerable to virus infection and genetic disorders, and, reveals the dynamics of allelic gene expression in specific organs at different stages. These results present the first comprehensive delineation of the spatiotemporal transcriptomic dynamics of human organogenesis. One Sentence SummaryThe spatiotemporal transcriptome atlas presents a comprehensive delineation of human embryogenesis after gastrulation.

developmental biology↗

bioRxiv2023

Origin and early divergence of tandem duplicated sorbitol transporter genes in Rosaceae

Sorbitol is a critical photosynthate and storage substance in the Rosaceae family. Sorbitol transporters (SOTs) play a vital role in facilitating sorbitol allocation from source to sink organs and sugar accumulation in sink organs. Despite observing gene duplications in the SOT gene family, the origin and evolutionary process of these duplications are unclear, due to the complicated interplay of whole genome duplications and tandem duplications. Here, we investigated the synteny relationships of all detected Polyol/Monosaccharide Transporter (PLT) genes in 61 angiosperm genomes and SOT genes in major representative Rosaceae genomes. Combining phylogenetic analysis, we elucidated the lineage-specific expansion and syntenic conservation of PLTs and SOTs across different plant lineages. We found that Rosaceae SOTs, as PLT family members, originated from a pair of PLT tandem duplicating genes belonging to Class III-A. Additionally, lineage-specific and synergistic duplications in Amygdaloideae had contributed to the expansion of SOTs in Rosaceae plants. Overall, our findings provide insights into the genomic origins, duplication, and divergence of SOT gene family members, which are fundamental for further functional characterizations of each member.

genomics↗

bioRxiv2023

Targeting MCL1-driven anti-apoptotic pathways to overcome hypomethylating agent resistance in RAS-mutated chronic myelomonocytic leukemia

RAS pathway mutations, which are present in 30% of patients with chronic myelomonocytic leukemia (CMML) at diagnosis, confer a high risk of resistance to and progression after hypomethylating agent (HMA) therapy, the current standard of care for the disease. Using single-cell, multi-omics technologies, we sought to dissect the biological mechanisms underlying the initiation and progression of RAS pathway-mutated CMML. We found that RAS pathway mutations induced the transcriptional reprogramming of hematopoietic stem and progenitor cells (HSPCs), which underwent proliferation and monocytic differentiation in response to cell-intrinsic and -extrinsic inflammatory signaling that also impaired immune cells functions. HSPCs expanded at disease progression and relied on the NF-KB pathway effector MCL1 to maintain their survival, which explains why patients with RAS pathway- mutated CMML do not benefit from BCL2 inhibitors such as venetoclax. Our study has implications for developing therapies to improve the survival of patients with RAS pathway- mutated CMML.

cancer biology↗

bioRxiv2023

The pluripotency factor Tex10 finetunes Wnt signaling for PGC and male germline development

Testis-specific transcript 10 (Tex10) is a critical factor for pluripotent stem cell maintenance and preimplantation development. Here, we dissect its late developmental roles in primordial germ cell (PGC) specification and spermatogenesis using cellular and animal models. We discover that Tex10 binds the Wnt negative regulator genes, marked by H3K4me3, at the PGC-like cell (PGCLC) stage in restraining Wnt signaling. Depletion and overexpression of Tex10 hyperactivate and attenuate the Wnt signaling, resulting in compromised and enhanced PGCLC specification efficiency, respectively. Using the Tex10 conditional knockout mouse models combined with single-cell RNA sequencing, we further uncover critical roles of Tex10 in spermatogenesis with Tex10 loss causing reduced sperm number and motility associated with compromised round spermatid formation. Notably, defective spermatogenesis in Tex10 knockout mice correlates with aberrant Wnt signaling upregulation. Therefore, our study establishes Tex10 as a previously unappreciated player in PGC specification and male germline development by fine-tuning Wnt signaling.

developmental biology↗

bioRxiv2023

Targeting DNA2 Overcomes Metabolic Reprogramming in Multiple Myeloma

DNA damage resistance is a major barrier to effective DNA-damaging therapy in multiple myeloma (MM). To discover novel mechanisms through which MM cells overcome DNA damage, we investigated how MM cells become resistant to antisense oligonucleotide (ASO) therapy targeting ILF2, a DNA damage regulator that is overexpressed in 70% of MM patients whose disease has progressed after standard therapies have failed. Here, we show that MM cells undergo an adaptive metabolic rewiring and rely on oxidative phosphorylation to restore energy balance and promote survival in response to DNA damage activation. Using a CRISPR/Cas9 screening strategy, we identified the mitochondrial DNA repair protein DNA2, whose loss of function suppresses MM cells ability to overcome ILF2 ASO-induced DNA damage, as being essential to counteracting oxidative DNA damage and maintaining mitochondrial respiration. Our study revealed a novel vulnerability of MM cells that have an increased demand for mitochondrial metabolism upon DNA damage activation. STATEMENT OF SIGNIFICANCEMetabolic reprogramming is a mechanism through which cancer cells maintain survival and become resistant to DNA-damaging therapy. Here, we show that targeting DNA2 is synthetically lethal in myeloma cells that undergo metabolic adaptation and rely on oxidative phosphorylation to maintain survival after DNA damage activation.

cancer biology↗

bioRxiv2023

STAT3 protects HSCs from intrinsic interferon signaling and loss of long-term blood-forming activity

STAT3 function in hematopoietic stem and progenitor cells (HSPCs) has been difficult to discern as Stat3 deficiency in the hematopoietic system induces systemic inflammation, which can impact HSPC activity. To address this, we established mixed bone marrow (BM) chimeric mice with CreER-mediated Stat3 deletion in 20% of the hematopoietic compartment. Stat3-deficient HSPCs had impaired hematopoietic activity and failed to undergo expansion in BM in contrast to Stat3-sufficient (CreER) controls. Single-cell RNA sequencing of Lin-ckit+Sca1+ BM cells revealed altered transcriptional responses in Stat3-deficient hematopoietic stem cells (HSCs) and multipotent progenitors, including intrinsic activation of cell cycle, stress response, and interferon signaling pathways. Consistent with their deregulation, Stat3-deficient Lin-ckit+Sca1+ cells accumulated {gamma}H2AX over time. Following secondary BM transplantation, Stat3-deficient HSPCs failed to reconstitute peripheral blood effectively, indicating a severe functional defect in the HSC compartment. Our results reveal essential roles for STAT3 in HSCs and suggest the potential for using targeted synthetic lethal approaches with STAT3 inhibition to remove defective or diseased HSPCs. Key PointsO_LISTAT3 is critical for hematopoietic activity and hematopoietic stem cell maintenance in non-inflammatory conditions C_LIO_LISTAT3 has a cell-intrinsic role in the suppression of interferon signaling and myeloid-skewed transcription in hematopoietic stem cells C_LI

immunology↗

bioRxiv2022

Vitamin C is an efficient natural product for prevention of SARS-CoV-2 infection by targeting ACE2 in both cell and in vivo mouse models

ACE2 is a major receptor for cell entry of SARS-CoV-2. Despite advances in targeting ACE2 to inhibit SARS-CoV-2s binding, how to efficiently and flexibly control ACE2 levels for prevention of SARS-CoV-2 infection has not been explored. Here, we revealed Vitamin C (VitC) administration as an effective strategy to prevent SARS-CoV-2 infection. VitC reduced ACE2 protein levels in a dose-dependent manner, while partial reduction of ACE2 can greatly restrict SARS-CoV-2 infection. Further studies uncovered that USP50 is a crucial regulator of ACE2 protein levels, and VitC blocks the USP50-ACE2 interaction, thus promoting K48-linked polyubiquitination at Lys788 and degradation of ACE2, without disrupting ACE2 transcriptional expression. Importantly, VitC administration reduced host ACE2 and largely blocked SARS-CoV-2 infection in mice. This study identified an in vivo ACE2 balance controlled by both USP50 and an essential nutrient VitC, and revealed a critical role and application of VitC in daily protection from SARS-CoV-2 infection. HighlightsO_LIVitC reduces ACE2 protein levels in a dose-dependent manner C_LIO_LIVitC and USP50 regulate K48-linked ubiquitination at Lys788 of ACE2 C_LIO_LIVitC blocks the interaction between USP50 and ACE2 C_LIO_LIVitC administration lowers host ACE2 and prevents SARS-CoV-2 infection in vivo C_LI O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=151 SRC="FIGDIR/small/499651v1_ufig1.gif" ALT="Figure 1"> View larger version (60K): org.highwire.dtl.DTLVardef@196682borg.highwire.dtl.DTLVardef@190f14dorg.highwire.dtl.DTLVardef@d22b59org.highwire.dtl.DTLVardef@1c0faa_HPS_FORMAT_FIGEXP M_FIG C_FIG The deubiquitinase USP50 controls ACE2 protein stability and levels, while Vitamin C blocks the USP50-ACE2 interaction and therefore results in ACE2 degradation, offering a flexible and efficient approach to protection of the host from SARS-CoV-2 infection.

microbiology↗

bioRxiv2022

Transcriptional drifts associated with environmental changes in endothelial cells

O_LIEnvironmental cues, such as physical forces and heterotypic cell interactions play a critical role in cell function, yet their collective contributions to transcriptional changes are unclear. Focusing on human endothelial cells, we performed broad individual sample analysis to identify transcriptional drifts associated with environmental changes that were independent of genetic background. Global gene expression profiling by RNA-seq and protein expression by LC-MS directed proteomics distinguished endothelial cells in vivo from genetically matched culture (in vitro) samples. Over 43% of the transcriptome was significantly changed by the in vitro environment. Subjecting cultured cells to long-term shear stress significantly rescued the expression of approximately 17% of genes. Inclusion of heterotypic interations by co-culture of endothelial cells with smooth muscle cells normalized approximately 9% of the original in vivo signature. We identify novel flow depedent genes, as well as, genes that necessitate heterotypic cell interactions to mimic the in vivo transcriptome. Our findings highlight specific genes and pathways that rely on contextual information and physical forces. C_LI

cell biology↗

bioRxiv2022

Sex differences in NK cells mediated by the X-linked epigenetic regulator UTX

Viral infection outcomes are sex-biased, with males generally more susceptible than females. Paradoxically, the numbers of anti-viral natural killer (NK) cells are increased in males compared to females. Using samples from mice and humans, we demonstrate that while numbers of male NK cells are increased compared to females, they display impaired production of the anti-viral cytokine IFN-{gamma}. These sex differences were not due solely to divergent levels of gonadal hormones, since these differences persisted in gonadectomized mice. Instead, these differences can be attributed to lower male expression of X-linked Kdm6a (UTX), an epigenetic regulator which escapes X inactivation in female NK cells. NK cell-specific UTX deletion in females phenocopied multiple features of male NK cells, which include increased numbers and reduced IFN-{gamma} production. Integrative ATAC-seq and RNA-seq analysis revealed a critical role for UTX in the regulation of chromatin accessibility and gene expression at loci important in NK cell homeostasis and effector function. Consequently, NK cell-intrinsic UTX levels are critical for optimal anti-viral immunity, since mice with NK cell-intrinsic UTX deficiency show increased lethality to mouse cytomegalovirus (MCMV) challenge. Taken together, these data implicate UTX as a critical molecular determinant of NK cell sex differences and suggest enhancing UTX function as a new strategy to boost endogenous NK cell anti-viral responses.

immunology↗

bioRxiv2022

Dynamic evolution of recently duplicated genes in Caenorhabditis elegans

As a major origin of evolutionary novelties, gene duplication is a widespread phenomenon across species. However, the evolutionary force that determines the fate of duplicate genes is still under debate. Here, we studied the functional evolution of duplicate genes at both macroevolution and microevolution scales using the genomic sequences of eleven Caenorhabditis species and 773 C. elegans wild isolates. We found that compared to older duplicate genes and single-copy genes, recently duplicated gene copies showed rapid turnover, large genetic diversity, and signs of balancing and positive selection within the species. Young duplicate genes have low basal expression restricted to a few tissues but show highly responsive expression towards pathogenic infections. Recently duplicated genes are enriched in chemosensory perception, protein degradation, and innate immunity, implicating their functions in enhancing adaptability to external perturbations. Importantly, we found that young duplicate genes are rarely essential, while old duplicate genes have the same level of essentiality as singletons, suggesting that essentiality develops over a long time. Together, our work in C. elegans demonstrates that natural selection shapes the dynamic evolutionary trajectory of duplicate genes. SignificanceThe "evolution by gene duplication" theory suggests that gene duplications provide the genetic materials for mutation and selection to act upon, expand the repertoire of molecular functions, and enable evolutionary novelty. Although various models were proposed to describe the fate of duplicate genes, empirical evidence for these models is limited. We analyzed gene duplications in eleven nematode Caenorhabditis species and studied the intraspecific variation of these duplicate genes among C. elegans wild strains. We found that compared to older duplicate gens and single-copy genes, recently duplicated genes show rapid turnover, large genetic diversity, and strong signs of balancing and positive selection but rarely develop essential functions. Our results describe the evolutionary trajectory of duplicate genes shaped by natural selection.

evolutionary biology↗

bioRxiv2022

The amyloid precursor protein modulates the position and length of the axon initial segment offering a new perspective on Alzheimer's disease genetics

The small A{beta} peptide has been hypothesized to be the main driver of Alzheimers disease (AD). A{beta} is a proteolytic cleavage product of a larger protein, the amyloid precursor protein (APP), whose normal functions remain largely unexplored. We report here activities of the full-length APP protein that relate directly to the etiology of AD. Increasing neuronal activity leads to a rapid increase in App gene expression. In both cultures of mouse cortical neurons and human iPSC-derived neurons, elevated APP protein changes the structure of the axon initial segment (AIS), the site of action potential initiation. In neurons with elevated APP, the AIS shortens in length and shifts in position away from the cell body. Both changes would be expected to reduce neuronal excitability. The AIS effects are due to the cell-autonomous actions of APP; exogenous A{beta} - either fibrillar or oligomeric - has no effect. The findings relate directly to AD in several ways. In culture, APP carrying the Swedish familial AD mutation (APPSwe) induces stronger AIS changes than wild type APP. Ankyrin G and {beta}IV-spectrin, scaffolding proteins of the AIS, both physically associate with APP, and APPSwe binds more avidly than wild type APP. Finally, neurons in the frontal cortex of humans with sporadic AD reveal histologically elevated levels of APP protein that invade the domain of the AIS, whose length is significantly shorter than that found in healthy control neurons. The findings offer an alternative explanation for the effects of at least some familial AD mutations. SignificanceIn familial Alzheimers disease (AD) the linkage between the genetics of APP, the neuropathology of the amyloid plaques and the symptoms of dementia are one of the strongest pieces of evidence supporting the amyloid cascade hypothesis - a conceptualization that marks the A{beta} peptide as the root cause of AD. Yet, formally, the genetics only point to APP, not its A{beta} breakdown product. We report here that the full-length APP protein affects the properties of the axon initial segment and through these changes serves as a dynamic regulator of neuronal activity. We propose that this newly discovered APP function offers a different, A{beta}-independent, view of the genetic evidence.

neuroscience↗

bioRxiv2021

Transcriptional evaluation of the ductus arteriosus at the single-cell level uncovers a requirement for vimentin for complete closure

OBJECTIVEFailure to close the ductus arteriosus immediately post-birth, patent ductus arteriosus (PDA), accounts for up to 10% of all congenital heart defects. Despite significant advances in PDA management options, including pharmacological treatment targeting the prostaglandin pathway, a proportion of patients fail to respond and must undergo surgical intervention. Thus, further refinement of the cellular and molecular mechanisms that govern vascular remodeling of this vessel is required. APPROACH AND RESULTSAs anticipated, single-cell RNA sequencing on the ductus arteriosus in mouse embryos at E18.5, P0.5, and P5, revealed broad transcriptional alterations in the endothelial, smooth muscle, and fibroblast cell compartments. Making use of these data sets, vimentin emerged as an interesting candidate for further investigation. Subsequent studies demonstrated that, in fact, mice with genetic deletion of vimentin fail to complete vascular remodeling of the ductus arteriosus, as per presence of a functional lumen. CONCLUSIONSThrough single-cell RNA-sequencing and by tracking closure of the ductus arteriosus postnatally in mice, we uncovered the unexpected contribution of vimentin in driving complete closure of the ductus arteriosus potentially through regulation of the Notch signaling pathway. HIGHLIGHTSO_LISingle-cell RNA-sequencing on the ductus arteriosus at E18.5, P0.5, and P5 reveals how the ductus arteriosus undergoes drastic transcriptional changes at the single-cell level. C_LIO_LIEndothelial cells increase levels of Vimentin, Notch1 and Jag1 transcripts soon after birth (P0.5), concurrent with ductus arteriosus closure. C_LIO_LILoss of vimentin, the major intermediate filament protein of endothelial cells, prevents proper permanent closure of the ductus arteriosus. C_LI

developmental biology↗

bioRxiv2021

Single cell transcriptomics reveals distinct effector profiles of infiltrating T cells in lupus skin and kidney

Cutaneous lupus is commonly present in patients with systemic lupus erythematosus (SLE) but can also exist as an isolated manifestation without further systemic involvement. T cells have been strongly suspected to contribute to the pathology of cutaneous lupus, yet our understanding of the T cell phenotypes and functions in the skin in lupus remains incomplete, and the extent to which lupus T cell infiltrates in skin resemble those in other tissue beds is unknown. Here, we present a detailed single-cell RNA sequencing profile of T and NK cell populations present within lesional and non-lesional skin biopsies of patients with cutaneous lupus. We identified multiple lymphocyte clusters, including both CD4 and CD8 T cells, NK cells, regulatory T cells, and a population of strongly interferon-responding cells that was present in patients with cutaneous lupus but absent in healthy donors. T cells across clusters from both lesional and non-lesional skin biopsies expressed elevated levels of interferon simulated genes (ISGs); however, compared to T cells from control skin, T cells from cutaneous lupus lesions did not show elevated expression profiles of activation, cytotoxicity, or exhaustion. Integrated analyses comparing skin T/NK cells to lupus nephritis kidney T/NK cells indicated that skin lymphocytes appeared less activated and lacked the expanded cytotoxic populations prominent in lupus nephritis. An integrated comparison of skin T cells from lupus and systemic sclerosis revealed similar activation profiles but an elevated ISG signature specific to cells from lupus skin biopsies. Overall, these data represent the first detailed transcriptomic analysis of the of T and NK cells in cutaneous lupus at the single cell level and have enabled a cross-tissue comparison that highlighted the stark differences in composition and activation of T/NK cells in distinct tissues in lupus.

immunology↗

bioRxiv2021

Intracellular Delivery of Antibodies for Selective Cell Signaling Interference

Many intracellular signaling events remain poorly characterized due to a general lack of tools to interfere with "undruggable" targets. Antibodies have the potential to elucidate intracellular mechanisms via targeted disruption of cell signaling cascades because of their ability to bind to a target with high specificity and affinity. However, due to their size and chemical composition, antibodies cannot innately cross the cell membrane, and thus access to the cytosol with these macromolecules has been limited. Here, we describe strategies for accessing the intracellular space with recombinant antibodies mediated by cationic lipid nanoparticles to selectively disrupt intracellular signaling events. To enable such investigations, we first produced a series of antibody constructs, known as scFv-Fcs, containing additional, genetically encoded negative charges located at the C-termini of the constructs. Preparing proteins with negatively charged motifs has previously been shown to enhance intracellular protein delivery with cationic lipids, but usually for the purpose of genome editing or targeted cell death. We started by generating derivatives of scFv-Fc17, an antibody construct previously reported to bind specifically to signal transducer and activator of transcription 3 (STAT3) phosphorylated at Tyr705 (pYSTAT3). We screened a small number of lipids from our combinatorial lipid library with flow cytometry and found that PBA-Q76-O16B facilitated the most efficient delivery of scFv-Fcs under the conditions tested. In HepG2 cells, we observed up to 60.5% delivery efficacy, while in a STAT3-luciferase reporter cell line up to 71.5% delivery efficacy was observed. These results demonstrated the feasibility of accessing the intracellular space with scFv-Fcs. However, we also note that no more than modest changes were observed upon changing the numbers of negative charges in these constructs during delivery. Characterization of the cytotoxicity, size, and encapsulation efficiency of scFv-Fcs with PBA-Q76-O16B revealed that the constructs were generally well-behaved, with addition of differing quantities of negative charge resulting in at most modest effects. Importantly, functional assays monitoring transcriptional activity in luciferase reporter cell lines and HepG2 cells demonstrated significant reduction of gene expression downstream of pYSTAT3 following delivery of scFv-Fc17 constructs. Together, our results establish the use of recombinantly produced antibodies to selectively interfere with cell signaling events driven by a single posttranslational modification. Efficient intracellular delivery of engineered antibodies opens up possibilities for modulation of previously "undruggable" targets, including for potential therapeutic applications.

bioengineering↗

bioRxiv2021

Non-lesional and Lesional Lupus Skin Share Inflammatory Phenotypes that Drive Activation of CD16+ Dendritic Cells

Cutaneous lupus erythematosus (CLE) is a disfiguring and poorly understood condition frequently associated with systemic lupus. Studies to date suggest that non-lesional keratinocytes play a role in disease predisposition, but this has not been investigated in a comprehensive manner or in the context of other cell populations. To investigate CLE immunopathogenesis, normal-appearing skin, lesional skin, and circulating immune cells from lupus patients were analyzed via integrated single-cell RNA-sequencing and spatial-seq. We demonstrate that normal-appearing skin of lupus patients represents a type I interferon-rich, prelesional environment that skews gene transcription in all major skin cell types and dramatically distorts cell-cell communication. Further, we show that lupus-enriched CD16+ dendritic cells undergo robust interferon education in the skin, thereby gaining pro-inflammatory phenotypes. Together, our data provide a comprehensive characterization of lesional and non-lesional skin in lupus and identify a role for skin education of CD16+ dendritic cells in CLE pathogenesis.

immunology↗

bioRxiv2021

Defining dysfunction due to loss of MECP2 in Rett Patient Brain

Rett Syndrome is characterized by a postnatal loss of neurophysiological function and regression of childhood development. Because the syndrome is X-linked and males with MECP2 mutations generally do not survive birth, the study of this syndrome has been complicated by the fact that in female brain, a portion of neurons express wild type MECP2, and another portion express a non-functional allele of MECP2. Therefore, bulk-RNA-sequencing of Rett brain is confounded by the presence of chimerism of neurons for functional MECP2 in neurons. We developed an approach that allows for single-nuclei transcriptional profiling of individual neurons and a direct comparison between neurons that express functional MECP2 with those that express the disease-causing allele. We found that mutant neurons from Rett brain show patterns of aberrant expression of synaptic and metabolic genes, both of which can be detected in in vitro models of Rett Syndrome. We used these resources to identify a role for POU2F1/OCT1 transcription factor in mediating the response to stress due to loss of MECP2, highlighting a potential key molecular regulator of stress in Rett neurons. Together, our new sorting approach enables us to highlight defective molecular and metabolic pathways in Rett brain neurons and suggests that in vitro models could serve as valuable tools to further study this syndrome and potentially for development of novel therapeutics.

molecular biology↗

bioRxiv2021

Inhibition of aryl hydrocarbon receptor signaling promotes the terminal differentiation of human erythrocytes

The aryl hydrocarbon receptor (AHR) plays an important role during mammalian embryo development. Inhibition of AHR signaling promotes the development of hematopoietic stem/progenitor cells. AHR also regulates the functional maturation of blood cells, such as T cells and megakaryocytes. However, little is known about the role of AHR modulation during the development of erythroid cells. In this study, we used the AHR antagonist StemRegenin 1 (SR1) and the AHR agonist 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) during different stages of human erythropoiesis to elucidate the function of AHR. We found that antagonizing AHR signaling improved the production of human embryonic stem cell (hESC)-derived erythrocytes and enhanced erythroid terminal differentiation. RNA-sequencing showed that SR1 treatment of proerythroblasts upregulated the expression of erythrocyte differentiation-related genes and downregulated actin organization-associated genes. We found that SR1 promoted F-actin remodeling in terminally differentiated erythrocytes, favoring the maturation of the cytoskeleton and enucleation. We demonstrated that the effects of AHR inhibition on erythroid maturation resulted from an increase in F-actin remodeling. Our findings help uncover the mechanism for AHR-mediated human erythroid cell differentiation. We also provide a new approach toward the large-scale production of functionally mature hPSC-derived erythrocytes for use in translational applications.

cell biology↗