Biology subjects

Choi, J.

Publications and source records attributed to Choi, J..

At least 181 records · Page 10Linked to original sources

bioRxiv2022

Spatial organization of the mouse retina at single cell resolution

The visual signal processing in the retina requires the precise organization of diverse neuronal types working in concert. We performed spatial transcriptomic profiling of over 100,000 cells from the mouse retina, uncovering the spatial distribution of all major retina cell types with over 100 cell subtypes. Our data revealed that the retina is organized in a laminar structure at the major cell type and subgroup level, both of which has strong correlation with the birth order of the cell. In contrast, overall random dispersion of cells within sub-laminar layers indicates that retinal mosaics are driven by dendritic field patterning rather than neuron soma placement. Through the integration of single cell transcriptomic and spatial data, we have generated the first comprehensive spatial single cell reference atlas of the mouse retina, a resource to the community and an essential step toward gaining a comprehensive understanding of the mechanism of retinal function. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/518972v1_ufig1.gif" ALT="Figure 1"> View larger version (76K): org.highwire.dtl.DTLVardef@1dc0eaforg.highwire.dtl.DTLVardef@480731org.highwire.dtl.DTLVardef@d0221borg.highwire.dtl.DTLVardef@6f5894_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2022

Cell circuits between leukemic cells and mesenchymal stem cells block lymphopoiesis by activating lymphotoxin-beta receptor signaling

Acute lymphoblastic and myeloblastic leukemias (ALL and AML) have been known to modify the bone marrow microenvironment and disrupt non-malignant hematopoiesis. However, the molecular mechanisms driving these alterations remain poorly defined. Here we show that leukemic cells turn-off lymphopoiesis and erythropoiesis shortly after colonizing the bone marrow. ALL and AML cells express lymphotoxin-1{beta}2 and activate LT{beta}R signaling in mesenchymal stem cells (MSCs), which turns off IL7 production and prevents non-malignant lymphopoiesis. We show that the DNA damage response pathway and CXCR4 signaling promote lymphotoxin-1{beta}2 expression in leukemic cells. Genetic or pharmacologic disruption of LT{beta}R signaling in MSCs restores lymphopoiesis but not erythropoiesis, reduces leukemic cell growth, and significantly extends the survival of transplant recipients. Similarly, CXCR4 blocking also prevents leukemia-induced IL7 downregulation, and inhibits leukemia growth. These studies demonstrate that acute leukemias exploit physiological mechanisms governing hematopoietic output as a strategy for gaining competitive advantage. One Sentence SummaryLeukemias colonize bone marrow niches and disrupt hematopoiesis. However, the cross-talk between leukemia and niche cells remains poorly understood. We show that leukemia activates LT{beta}R in mesenchymal stem cells which suppresses IL7 production and IL7-dependent lymphopoiesis and accelerates leukemia growth.

immunology↗

bioRxiv2022

IL-12-expressing highly immunogenic recombinant modified vaccinia virus Ankara reprograms tumor-infiltrating myeloid cells to overcome immune resistance

Resistance to immune checkpoint blockade (ICB) remains a major obstacle in cancer immunotherapy. We rationally engineered a second-generation recombinant Modified Vaccinia virus Ankara (MQ833) by deleting viral immune-evasion genes (E3L, E5R, WR199) and incorporating Flt3L, OX40L, and matrix-anchored IL12. Intratumoral MQ833 elicited robust tumor regressions across multiple models, including ICB-resistant and MHC-I-deficient tumors. Single-cell RNA sequencing revealed extensive remodeling of the tumor microenvironment, characterized by neutrophil and monocyte recruitment and activation, M2 macrophage depletion, M1 polarization, and effector T-cell differentiation and proliferation. Conditional Ifnar1 knockout mice demonstrated that MQ833 efficacy requires type I interferon signaling in neutrophils, macrophages/monocytes, and T cells. Moreover, Nos2 deficiency impaired therapeutic efficacy, confirming iNOS myeloid cells as key effectors. Together, these findings show that MQ833 activates innate-adaptive IFN cross-talk to reprogram myeloid and T cells, defining a rationally designed viral immunotherapy capable of overcoming ICB resistance. GRAPHIC ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=179 SRC="FIGDIR/small/509429v2_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@496f37org.highwire.dtl.DTLVardef@124bd78org.highwire.dtl.DTLVardef@1134528org.highwire.dtl.DTLVardef@216da6_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2022

Topical GZ21T inhibits the growth of actinic keratoses in a UVB induced model of skin carcinogenesis

Actinic keratoses (AKs) are premalignant intraepidermal neoplasms that occur as a result of cumulative sun damage. AKs commonly relapse, and up to 16% undergo malignant transformation into cutaneous squamous cell carcinoma (cSCC). There is a need for novel therapies that reduce the quantity and surface area of AKs as well as prevent malignant transformation to cSCCs. We recently showed that GZ17-6.02, an anti-cancer agent composed of curcumin, haramine, and isovanillin, inhibited the growth of H297.T cells. The present study evaluated the efficacy of a novel topical formulation of GZ17-6.02, known as GZ21T, in a murine model of AK generated by exposing SKH1 mice to ultraviolet irradiation. Treatment of mice with topical GZ21T inhibited the growth of AKs by decreasing both lesion count (p=.028) and surface area occupied by tumor (p=.026). GZ21T also suppressed the progression of AKs to cSCC by decreasing the count (p=.047) and surface area (p=.049) of lesions more likely to represent cSCC. RNA sequencing and proteomic analyses revealed that GZ21T suppressed several pathways, including MAPK (p=.026), Pi3K-Akt (p=.028), HIF-1 (p=.030), Wnt (p=.031), insulin (p=.011), and ErbB (p=.006) signaling. GZ21T also upregulated the autophagy-promoting protein AMPK, while suppressing proteins such as PD-L1, glutaminase, pAkt1 S473, and eEF2K. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/506864v1_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@1254e6corg.highwire.dtl.DTLVardef@3fd190org.highwire.dtl.DTLVardef@1d75eb5org.highwire.dtl.DTLVardef@8afc97_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2022

Intestinal stem cell aging at single-cell resolution: functional perturbations alter cell developmental trajectory reversed by gerotherapeutics

The intestinal epithelium is consists of cells derived from continuously cycling Lgr5hi intestinal stem cells (Lgr5hi ISCs) that mature developmentally in an order fashion as the cells progress along the crypt-luminal axis. Perturbed function of Lgr5hi ISCs with aging is well documented but the consequent impact on overall mucosal homeostasis has not been defined. Using single-cell RNA sequencing, the progressive maturation of progeny was dissected in mouse intestine, which revealed that transcriptional reprogramming with aging in Lgr5hi ISCs retarded cell maturation in their progression along the crypt-luminal axis. Importantly, treatment with metformin or rapamycin at a late stage of mouse lifespan reversed the effects of aging on function of Lgr5hi ISCs and subsequent maturation of progenitors. The effects of metformin and rapamycin overlapped in reversing changes of transcriptional profiles, but were also complementary, with metformin more efficient than rapamycin in correcting the developmental trajectory. Therefore, our data identify novel effects of aging on stem cells and the maturation of their daughter cells contributing to the decline of functional Lgr5hi ISCs and the correction by geroprotectors.

cell biology↗

bioRxiv2022

IL-2 secreting T helper cells promote EF B cell maturation via intrinsic regulation of B cell mTOR/AKT/Blimp-1 axis.

SUMMARYB cells are fundamental players in the secretion of antibodies and the establishment of long-term memory-based immunity. Integration of signals from TLRs, BCR stimulation, and T helper cell-derived cytokines can all dictate B cell differentiation and their metabolic state. However, while important components of this interaction have been described, the precise signaling networks and mechanisms regulating B cell fate are not fully understood. Here, we elucidated the role of interleukin-2 (IL-2) in determining early B cell fate decisions and inducing plasma cell reprogramming. Using both in vitro culture systems and in vivo models of immunization, alongside CRISPR-based genome editing of antigen-specific T and B cells, we identify a role for T helper-secreted IL-2 in inducing high expression of Irf4 and Blimp-1 in activated cognate B cells, enhancing plasma cell differentiation. Induction of this cascade promotes their differentiation and drives metabolic reprogramming through the regulation of mTOR/AKT/Blimp-1 axis.

immunology↗

bioRxiv2022

Rad51 and Dmc1 have similar tolerance for mismatches in yeast meiosis

In many eukaryotes, including both budding yeast and mammals, repair of double-strand breaks (DSBs) is carried out by different apparatus in somatic and meiotic cells. In mitotic cells, Rad51 recombinase, acting with Rad54, facilitates the search for homology and DNA strand exchange. In meiosis, Rad51 is inhibited by Hed1 and plays only an effector role, while strand exchange is driven by Rad51s homolog, Dmc1, acting with Rad54s homolog, Rdh54/Tid1. To directly compare the activities of Rad51 and Dmc1 and especially their tolerance for recombination between divergent sequences, we created diploids in which a site-specific DSB was created by HO endonuclease, either under control of a galactose-inducible promoter or a meiosis-specific SPO13 promoter. Homologous recombination was measured by an ectopic break-induced replication (BIR) assay in which a 108-bp homologous sequence shared between the DSB end and the donor sequence could be easily modified. As previously shown for a haploid mitotic strain, BIR efficiency decreased with increasing divergence between donor and recipient, but repair occurred even when every 6th base pair was mismatched. There was little difference in the tolerance of mismatches in mitotic haploids or meiotic diploids; however, there were notable differences in meiotic diploids when recombination was facilitated by Dmc1 or when Rad51 took over from Dmc1 in both hed1{Delta} and dmc1{Delta} hed1{Delta} mutants. We found that Dmc1 and Rad51 are similarly tolerant of mismatches during meiotic recombination in budding yeast. Surveillance of mismatches by the Msh2 mismatch repair protein proved to be Dmc1-specific. In all cases, assimilation of mismatches into the BIR product was dependent on the 3 to 5 exonuclease activity of DNA polymerase {delta}. Author SummaryIn many eukaryotes, including both budding yeast and mammals, repair of double-strand breaks (DSBs) is carried out by different apparatus in somatic and meiotic cells. In mitotic cells, Rad51 recombinase, acting with Rad54, facilitates the search for homology and DNA strand exchange. In budding yeast meiosis, Rad51 is inhibited by Hed1 and plays only an effector role, while strand exchange is driven by Rad51s homolog, Dmc1, acting with Rad54s homolog, Rdh54/Tid1. To directly compare the activities of Rad51 and Dmc1 and especially their tolerance for recombination between divergent sequences, we created diploids in which a site-specific DSB was created by HO endonuclease. Homologous recombination was measured by an ectopic break-induced replication (BIR) assay in which recombination occurred between a 108-bp homologous sequence shared between the DSB end and the donor sequence. The donor sequence could be easily modified to introduce different arrangements of mismatches. BIR efficiency decreased with increasing divergence between donor and recipient, but repair occurred even when every 6th base pair was mismatched. There was little difference in the tolerance of mismatches in mitotic or meiotic diploids; however, there were notable differences in meiotic diploids when recombination was facilitated by Dmc1 or when Dmc1 was deleted and Rad51 was activated. We found that Dmc1 and Rad51 are similarly tolerant of mismatches during meiotic recombination. Surveillance of mismatches by the Msh2 mismatch repair protein proved to be Dmc1-specific. As in mitotic cells, the assimilation of mismatches into the BIR product was dependent on the 3 to 5 exonuclease activity of DNA polymerase {delta}.

genetics↗

bioRxiv2022

Oligomerisation of a plant helper NLR requires cell-surface and intracellular immune receptor activation

Plant disease resistance involves both detection of microbial molecular patterns by cell-surface pattern recognition receptors and detection of pathogen effectors by intracellular NLR immune receptors. NLRs are classified as sensor NLRs, involved in effector detection, or helper NLRs required for sensor NLR signalling. TIR-domain-containing sensor NLRs (TNLs) require helper NLRs NRG1 and ADR1 for resistance, and their activation of defense also requires the lipase-domain proteins EDS1, SAG101 and PAD4. We investigated how the helper NLR NRG1 supports TNL-initiated immunity with EDS1 and SAG101. We find that NRG1 associates with EDS1 and SAG101 at the plasma membrane and in the nucleus, but only self-associates at the plasma membrane. Activation of TNLs is sufficient to trigger NRG1-EDS1-SAG101 interaction, but cell-surface receptor-initiated defense is also required to form an oligomeric Resistosome. The data point to formation of NRG1-EDS1-SAG101 heterotrimers in the nucleus upon intracellular receptor activation alone and indicate formation of NRG1-EDS1-SAG101 Resistosomes at the plasma membrane upon co-activation of intracellular and cell surface-receptor pathways.

plant biology↗

bioRxiv2022

USP11 promotes endothelial apoptosis-resistance in pulmonary hypertension by deubiquitinating HINT3

IntroductionPulmonary arterial hypertension (PAH) is a progressive, lethal, and incurable disease of the pulmonary vasculature. Evolving evidence indicates that the ubiquitin-specific proteases (USPs), play an important role in the pathogenesis of PAH by deubiquitinating key proteins involved in cell proliferation, migration, and apoptosis. Our genome-wide association study (GWAS) analysis-paired with transcriptomic profiling indicated that deubiquitinase USP11 and histidine triad nucleotide binding protein 3 (HINT3) are positively correlated and that their expression increased in lungs of PAH patients compared to control (fail donor) group, and inversely correlated with survival. However, mechanisms and function of the USP11/HNT3 axis have not been explored in PAH. Therefore, we aimed to investigate that HINT3 stabilized by USP11 activation links to endothelial apoptosis-resistance in PAH. Methods and ResultsExpression of USP11 and HINT3 was increased in the lungs of idiopathic PAH (IPAH) patients and Hypoxia/Sugen-treated mice using qRT-PCR and Western blot analyses. USP11 and HINT3 interacted physically as shown by co-immunoprecipitation (co-IP) assay in human pulmonary artery endothelial cells (HPAECs). HINT3 levels were decreased upon transfection of HA-tagged Ubi plasmid into HPAECs. Pretreatment with the potent proteasome inhibitor MG132 prolonged the half-life of HINT3 protein, indicating that HINT3 is degraded by polyubiquitination. HINT3 was stabilized and destabilized by forced overexpression or siRNA knockdown of USP11 respectively. Similarly, treatment with mitoxantrone, a USP11 antagonist, reduced HPAEC HINT3 expression. HINT3 interacted with the antiapoptotic mediator, BCL2. Overexpression of USP11 increased BCL2 content, congruent to elevated lung tissue levels seen in IPAH patients and Hypoxia/Sugen-treated mice. Conversely, knockdown of HINT3 function led to depletion of BCL2. ConclusionsThe HINT3-USP11 axis contributes to apoptosis-resistance in pulmonary artery endothelial cells, as is potentially a novel and attractive therapeutic target for ubiquitination modulators.

physiology↗

bioRxiv2022

Intracellular Calcium links Milk Stasis to Lysosome Dependent Cell Death during Mammary Gland Involution

Involution of the mammary gland after lactation is a dramatic example of coordinated cell death. Weaning causes distension of the alveolar structures due to the accumulation of milk, which, in turn, activates STAT3 and initiates a caspase- independent but lysosome-dependent cell death (LDCD) pathway. Although the importance of STAT3 and LDCD in early mammary involution is well established, it has not been entirely clear how milk stasis activates STAT3. In this report, we demonstrate that protein levels of the PMCA2 calcium pump are significantly downregulated within 2- 4 hours of experimental milk stasis. Reductions in PMCA2 expression correlate with an increase in cytoplasmic calcium in vivo as measured by multiphoton intravital imaging of GCaMP6f fluorescence. These events occur concomitant with the appearance of nuclear pSTAT3 expression but prior to significant activation of LDCD or its previously implicated mediators such as LIF, IL6 and TGF{beta}3, all of which appear to be upregulated by increased intracellular calcium. We also observed that milk stasis, loss of PMCA2 expression and increased intracellular calcium levels activate TFEB, an important regulator of lysosome biogenesis. This is the result of increased TGF{beta} signaling and inhibition of cell cycle progression. Finally, we demonstrate that increased intracellular calcium activates STAT3 by inducing degradation of its negative regulator, SOCS3, a process which also appears to be mediated by TGF{beta} signaling. In summary, these data suggest that intracellular calcium serves as an important proximal biochemical signal linking milk stasis to STAT3 activation, increased lysosomal biogenesis, and lysosome- mediated cell death.

cell biology↗

bioRxiv2022

The Human Dendritic Cell Atlas: An integrated transcriptional tool to study human dendritic cell biology

Dendritic cells (DCs) are functionally diverse and are present in most adult tissues, however progress in understanding human DC biology is hampered by a relatively small number of these in circulation and by limited access to human tissues. We built a transcriptional atlas of human DCs by combining samples from 14 expression profiling studies derived from 10 laboratories. We identified significant gene expression variation of DC subset-defining markers across tissue-type and upon viral or bacterial stimulation. We further highlight critical gaps between in vitro-derived DC subsets and their in vivo counterparts and provide evidence that monocytes or cord blood progenitor in vitro-differentiated DCs fail to capture the repertoire of primary DC subsets or behaviours. In constructing a reference DC atlas, we provide an important resource for the community wishing to identify and annotate tissue-specific DC subsets from single-cell datasets, or benchmark new in vitro models of DC biology. Key PointsO_LIA reference atlas of human DC that allows benchmarking of in vitro DC models C_LIO_LIMeta-analysis of 14 integrated studies demonstrate that human conventional dendritic cells have distinct tissue-of-origin phenotypes C_LIO_LIUser uploads allow tissue-relevant annotation of human DC subsets from single cell datasets C_LIO_LIKey subset markers are altered by tissue or activation status C_LIO_LIGaps between in vitro-differentiated DC and in vivo counterparts are partially rescued by humanized mouse models, or coculture with NOTCH-ligands. C_LI

immunology↗

bioRxiv2022

Proliferation is a driver of quorum sensing in an in vitro model of tissue resident macrophages

Macrophages coordinate the initial host inflammatory response to tissue infection, as well as mediating the reparative phase, by producing growth factors that promote tissue repair. One model of this functional dichotomy is that peripherally recruited monocyte-derived macrophages drive acute inflammatory responses to infection, whereas tissue-resident macrophages are responsible for tissue repair. Alternatively, inflammation and repair may be inter-dependent molecular programs, such that both recruited and resident cells have equivalent capacity to contribute. Repeated exposure to pathogenic challenge results in innate tolerance, which may also alter the contributions of discrete macrophage populations to inflammation or repair. In this study a village model of tissue resident and recruited macrophages was created using induced pluripotent stem cell-derived macrophages and peripheral blood monocyte-derived macrophages, respectively. Population responses to repeated exposure to lipopolysaccharide were assessed with single-cell RNA sequencing and donors demultiplexed with Vireo. A subset of genes escaped classical tolerance programs in the iPSC, but not monocyte-derived macrophages, and this was associated with differences in their proliferative capacity. This suggests that targeting the proliferative resident macrophages would be most effective to limit inflammatory signaling.

systems biology↗

bioRxiv2022

SARS-CoV-2 Spike N-Terminal Domain modulates TMPRSS2-dependent viral entry and fusogenicity

Over 20 mutations have been identified in the N-Terminal Domain (NTD) of SARS-CoV-2 spike and yet few of them are fully characterised. Here we first examined the contribution of the NTD to infection and cell-cell fusion by constructing different VOC-based chimeric spikes bearing B.1617 lineage (Delta and Kappa variants) NTDs and generating spike pseudotyped lentivirus (PV). We found the Delta NTD on a Kappa or WT background increased spike S1/S2 cleavage efficiency and virus entry, specifically in Calu-3 lung cells and airway organoids, through use of TMPRSS2. We have previously shown Delta spike confers rapid cell-cell fusion kinetics; here we show that increased fusogenicity can be conferred to WT and Kappa variant spikes by transfer of the Delta NTD. Moving to contemporary variants, we found that BA.2 had higher entry efficiency in a range of cell types as compared to BA.1. BA.2 showed higher fusogenic activity than BA.1, but the BA.2 NTD could not confer higher fusion to BA.1 spike. There was low efficiency of TMPRSS2 usage by both BA.1 and BA.2, and chimeras of Omicron BA.1 and BA.2 spikes with a Delta NTD did not result in more efficient use of TMRPSS2 or cell-cell fusogenicity. We conclude that the NTD allosterically modulates S1/S2 cleavage and spike-mediated functions such as entry and cell-cell fusion in a spike context dependent manner, and allosteric interactions may be lost when combining regions from more distantly related spike proteins. These data may explain the lack of successful SARS-CoV-2 inter-variant recombinants bearing breakpoints within spike.

microbiology↗

bioRxiv2022

A neurocomputational theory of action regulation predicts motor behavior in neurotypical individuals and patients with Parkinsons disease

Surviving in an uncertain environment requires not only the ability to select the best action, but also the flexibility to withhold inappropriate actions when the environmental conditions change. Although selecting and withholding actions have been extensively studied in both human and animals, there is still lack of consensus on the mechanism underlying these action regulation functions, and more importantly, how they inter-relate. A critical gap impeding progress is the lack of a computational theory that will integrate the mechanisms of action regulation into a unified framework. The current study aims to advance our understanding by developing a neurodynamical computational theory that models the mechanism of action regulation that involves suppressing responses, and predicts how disruption of this mechanism can lead to motor deficits in Parkinsons disease (PD) patients. We tested the model predictions in neurotypical individuals and PD patients in three behavioral tasks that involve free action selection between two opposed directions, action selection in the presence of conflicting information and abandoning an ongoing action when a stop signal is presented. Our results and theory suggest an integrated mechanism of action regulation that affects both action initiation and inhibition. When this mechanism is disrupted, motor behavior is affected, leading to longer reaction times and higher error rates in action inhibition. Author SummaryHumans can rapidly regulate actions according to updated demands of the environment. A key component of action regulation is action inhibition, the failure of which contributes to various neuropsychiatric disorders. When faced with multiple choices, dealing with conflicting information, or current actions become inappropriate or unwanted, we should be able to pause or completely abandon actions. Despite extensive efforts to understand how the brain selects, pauses, and abandons actions based on environmental demands, the mechanisms underlying these action regulation functions and, perhaps more importantly, how they inter-relate remain elusive. Part of this challenge lies in the fact that these mechanisms were rarely explored together, making it difficult to develop a unified theory that explains the computational aspects of action regulation functions. The current study introduces a large-scale model that better characterizes the computations of action regulation functions, how they are implemented within brain networks that involve frontal, motor and basal ganglia (BG) circuits, and how disruption of these circuits can lead to deficits in motor behavior seen in Parkinsons disease (PD).The model was developed by studying the motor behavior of healthy individuals and PD patients in three motor tasks that involve action inhibition. Overall, the model explains many key aspects on how the brain regulates actions that involve inhibitory processes, opening new avenues for improving and developing therapeutic interventions for diseases that may involve these circuits.

neuroscience↗

bioRxiv2022

Extensive de novo activity stabilizes epigenetic inheritance of CG methylation in Arabidopsis transposons

Cytosine methylation within CG dinucleotides (mCG) can be epigenetically inherited over many generations. Such inheritance is thought to be mediated by a semiconservative mechanism that produces binary present/absent methylation patterns. However, we show here that in Arabidopsis thaliana h1ddm1 mutants, intermediate heterochromatic mCG is stably inherited across many generations and is quantitatively associated with transposon expression. We develop a mathematical model that estimates the rates of semiconservative maintenance failure and de novo methylation at each transposon, demonstrating that mCG can be stably inherited at any level via a dynamic balance of these activities. We find that DRM2 - the core methyltransferase of the RNA-directed DNA methylation pathway - catalyzes most of the heterochromatic de novo mCG, with de novo rates orders of magnitude higher than previously thought, whereas chromomethylases make smaller contributions. Our results demonstrate that stable epigenetic inheritance of mCG in plant heterochromatin is enabled by extensive de novo methylation.

genetics↗

bioRxiv2022

Genomic demography of world's ethnic groups and their genomic identity between two individuals

All current categorizations of human population, such as ethnicity, ancestry and race, are based on various selections and combinations of subjectively- and/or qualitatively-defined characteristics, such as ancestral lineage/location, cultural/societal norm, language, skin color and other phenotypes and traits perceived by the members within or from outside of the categorized group. Yet, such categorization has been broadly used also in the fields of human genetics, health sciences and medical practices (e.g., 1,2,3), where the observed health characteristics are objectively and quantitatively definable, but the population categorization is not yet available. Here we show the feasibility of deriving a whole-genome-based categorization that is objectively definable and quantitatively measurable. We observe that: (a) the worlds ethnic populations form about 14 genomic groups (GGs); (b) each GG consists of multiple ethnic groups (EGs); and (c) at an individual level, approximately 99.8%, on average, of the whole genome contents are identical between any two individuals regardless of their GGs or EGs.

evolutionary biology↗

bioRxiv2022

Dietary Induced Dynamic Plasticity of Intestinal Stem Cells and the Mucosa in Elevating Risk for Tumor Development

NWD1, a purified rodent diet establishing mouse exposure to key nutrients recapitulating levels that increase risk for intestinal cancer, reproducibly causes sporadic intestinal and colonic tumors in the mouse, reflecting human etiology, incidence, frequency and lag with developmental age. Complex NWD1 reprogramming of stem cells and lineages was deconvolved by bulk and scRNAseq, scATACseq, functional genomics and imaging. NWD1 extensively, rapidly, and reversibly reprogrammed Lgr5hi stem cells, epigenetically down-regulating Ppargc1a expression, altering mitochondrial structure and function. This suppressed Lgr5hi stem cell functions and developmental maturation of Lgr5hi cell progeny as cells progressed through progenitor cell compartments, recapitulated by Ppargc1a genetic inactivation in Lgr5hi cells in vivo. Mobilized Bmi1+, Ascl2hi cells adapted lineages to the nutritional environment and elevated antigen processing and presentation pathways, especially in mature enterocytes, causing chronic, pro-tumorigenic low-level inflammation. There were multiple parallels between NWD1 remodeling of stem cells and lineages with pathogenic mechanisms in human inflammatory bowel disease, also pro-tumorigenic. Moreover, the shift to alternate stem cells reflects that the balance between Lg5 positive and negative stem cells in supporting human colon tumors is determined by environmental influences. Stem cell and lineage plasticity in response to nutrients supports historic concepts of homeostasis as a continual adaptation to environment, with the human mucosa likely in constant flux in response to changing nutrient exposures. Thus, although oncogenic mutations provide a competitive advantage to intestinal epithelial cells in clonal expansion, the competition is on a playing field dynamically sculpted by the nutritional environment, influencing which cells dominate in mucosal maintenance and tumorigenesis.

cancer biology↗

bioRxiv2022

Arginine 65 methylation of Neurogenin 3 by PRMT1 is a prerequisite for development of hESCs into pancreatic endocrine cells

In the developing pancreas, Neurogenin 3 (NGN3) is a key transcription factor in the cell fate determination of endocrine progenitors (EPs). Although the activation and stability of NGN3 are regulated by phosphorylation, the role of arginine methylation of NGN3 is poorly understood. Here, we report arginine 65 methylation of NGN3 is absolutely required for the pancreatic lineage development of human embryonic stem cells (hESCs) in vitro. First, we found inducible protein arginine methyltransferase 1 (PRMT1)-knockout (P-iKO) hESCs did not differentiate from EPs to endocrine cells (ECs) in the presence of doxycycline. Loss of PRMT1 caused an accumulation of NGN3 in the cytoplasm of EPs and blocked NGN3s transcriptional activity in PRMT1-KO EPs. We also found that PRMT1 specifically methylates NGN3 arginine 65, and this modification is a prerequisite for ubiquitin-mediated NGN3 degradation. Our findings indicate arginine 65 methylation of NGN3 is a key molecular switch in hESCs in vitro permitting the differentiation into pancreatic endocrine lineages.

developmental biology↗