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1.
Nat Commun ; 15(1): 3744, 2024 May 03.
Artigo em Inglês | MEDLINE | ID: mdl-38702321

RESUMO

Cellular composition and anatomical organization influence normal and aberrant organ functions. Emerging spatial single-cell proteomic assays such as Image Mass Cytometry (IMC) and Co-Detection by Indexing (CODEX) have facilitated the study of cellular composition and organization by enabling high-throughput measurement of cells and their localization directly in intact tissues. However, annotation of cell types and quantification of their relative localization in tissues remain challenging. To address these unmet needs for atlas-scale datasets like Human Pancreas Analysis Program (HPAP), we develop AnnoSpat (Annotator and Spatial Pattern Finder) that uses neural network and point process algorithms to automatically identify cell types and quantify cell-cell proximity relationships. Our study of data from IMC and CODEX shows the higher performance of AnnoSpat in rapid and accurate annotation of cell types compared to alternative approaches. Moreover, the application of AnnoSpat to type 1 diabetic, non-diabetic autoantibody-positive, and non-diabetic organ donor cohorts recapitulates known islet pathobiology and shows differential dynamics of pancreatic polypeptide (PP) cell abundance and CD8+ T cells infiltration in islets during type 1 diabetes progression.


Assuntos
Algoritmos , Diabetes Mellitus Tipo 1 , Pâncreas , Proteômica , Humanos , Proteômica/métodos , Diabetes Mellitus Tipo 1/patologia , Diabetes Mellitus Tipo 1/metabolismo , Pâncreas/citologia , Pâncreas/metabolismo , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/citologia , Análise de Célula Única/métodos , Redes Neurais de Computação , Linfócitos T CD8-Positivos/metabolismo , Citometria por Imagem/métodos
2.
Cell Rep Med ; : 101535, 2024 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-38677282

RESUMO

Type 1 diabetes (T1D) is a chronic condition in which beta cells are destroyed by immune cells. Despite progress in immunotherapies that could delay T1D onset, early detection of autoimmunity remains challenging. Here, we evaluate the utility of machine learning for early prediction of T1D using single-cell analysis of islets. Using gradient-boosting algorithms, we model changes in gene expression of single cells from pancreatic tissues in T1D and non-diabetic organ donors. We assess if mathematical modeling could predict the likelihood of T1D development in non-diabetic autoantibody-positive donors. While most autoantibody-positive donors are predicted to be non-diabetic, select donors with unique gene signatures are classified as T1D. Our strategy also reveals a shared gene signature in distinct T1D-associated models across cell types, suggesting a common effect of the disease on transcriptional outputs of these cells. Our study establishes a precedent for using machine learning in early detection of T1D.

3.
Phys Rev E ; 109(3-1): 034607, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38632760

RESUMO

We use a standard minimal active Brownian model to investigate the osmotic-like effective pressure generated by active fluids on fixed hollow inclusions. These inclusions are enclosed by a permeable (albeit nonflexible) membrane, and the interior and exterior regions of the inclusions have different particle motility strengths. We consider both rectangular and disklike inclusions and analyze the effects of various system parameters, such as excluded volume interaction between active particles, hardness of membrane, and active particle density, on the effective pressure produced on the enclosing membrane. We focus on the range of intermediate to high motility strengths and analyze the effective pressure in the steady state. Our findings for the active pressure produced in the interior and exterior regions of the inclusion indicate that the pressure is higher in the region with lower motility due to the relatively stronger accumulation of active particles.

4.
BMC Genomics ; 25(1): 427, 2024 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-38689254

RESUMO

BACKGROUND: Current approaches to profile the single-cell transcriptomics of human pancreatic endocrine cells almost exclusively rely on freshly isolated islets. However, human islets are limited in availability. Furthermore, the extensive processing steps during islet isolation and subsequent single cell dissolution might alter gene expressions. In this work, we report the development of a single-nucleus RNA sequencing (snRNA-seq) approach with targeted islet cell enrichment for endocrine-population focused transcriptomic profiling using frozen archival pancreatic tissues without islet isolation. RESULTS: We cross-compared five nuclei isolation protocols and selected the citric acid method as the best strategy to isolate nuclei with high RNA integrity and low cytoplasmic contamination from frozen archival human pancreata. We innovated fluorescence-activated nuclei sorting based on the positive signal of NKX2-2 antibody to enrich nuclei of the endocrine population from the entire nuclei pool of the pancreas. Our sample preparation procedure generated high-quality single-nucleus gene-expression libraries while preserving the endocrine population diversity. In comparison with single-cell RNA sequencing (scRNA-seq) library generated with live cells from freshly isolated human islets, the snRNA-seq library displayed comparable endocrine cellular composition and cell type signature gene expression. However, between these two types of libraries, differential enrichments of transcripts belonging to different functional classes could be observed. CONCLUSIONS: Our work fills a technological gap and helps to unleash frozen archival pancreatic tissues for molecular profiling targeting the endocrine population. This study opens doors to retrospective mappings of endocrine cell dynamics in pancreatic tissues of complex histopathology. We expect that our protocol is applicable to enrich nuclei for transcriptomics studies from various populations in different types of frozen archival tissues.


Assuntos
Núcleo Celular , Proteína Homeobox Nkx-2.2 , Proteínas de Homeodomínio , Ilhotas Pancreáticas , Proteínas Nucleares , Análise de Sequência de RNA , Análise de Célula Única , Fatores de Transcrição , Humanos , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/citologia , Análise de Célula Única/métodos , Análise de Sequência de RNA/métodos , Núcleo Celular/genética , Núcleo Celular/metabolismo , Perfilação da Expressão Gênica/métodos , Pâncreas/metabolismo , Pâncreas/citologia , Transcriptoma
5.
Am J Transplant ; 2024 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-38467375

RESUMO

Durable tolerance in kidney transplant recipients remains an important but elusive goal. We hypothesized that adding B cell depletion to T cell depletion would generate an immune milieu postreconstitution dominated by immature transitional B cells, favoring tolerance. The Immune Tolerance Network ITN039ST Research Study of ATG and Rituximab in Renal Transplantation was a prospective multicenter pilot study of live donor kidney transplant recipients who received induction with rabbit antithymocyte globulin and rituximab and initiated immunosuppression (IS) withdrawal (ISW) at 26 weeks. The primary endpoint was freedom from rejection at 52 weeks post-ISW. Six of the 10 subjects successfully completed ISW. Of these 6 subjects, 4 restarted immunosuppressive medications due to acute rejection or recurrent disease, 1 remains IS-free for over 9 years, and 1 was lost to follow-up after being IS-free for 42 weeks. There were no cases of patient or graft loss. CD19+ B cell frequencies returned to predepletion levels by 26 weeks posttransplant; immunoglobulin D+CD27--naïve B cells predominated. In contrast, memory cells dominated the repopulation of the T cell compartment. A regimen of combined B and T cell depletion did not generate the tolerogenic B cell profile observed in preclinical studies and did not lead to durable tolerance in the majority of kidney transplant recipients.

6.
Gastroenterology ; 2024 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-38494035

RESUMO

BACKGROUND & AIMS: Hirschsprung's disease is defined by the absence of the enteric nervous system (ENS) from the distal bowel. Primary treatment is "pull-through" surgery to remove bowel that lacks ENS, with reanastomosis of "normal" bowel near the anal verge. Problems after pull-through are common, and some may be due to retained hypoganglionic bowel (ie, low ENS density). Testing this hypothesis has been difficult because counting enteric neurons in tissue sections is unreliable, even for experts. Tissue clearing and 3-dimensional imaging provide better data about ENS structure than sectioning. METHODS: Regions from 11 human colons and 1 ileal specimen resected during Hirschsprung's disease pull-through surgery were cleared, stained with antibodies to visualize the ENS, and imaged by confocal microscopy. Control distal colon from people with no known bowel problems were similarly cleared, stained, and imaged. RESULTS: Quantitative analyses of human colon, ranging from 3 days to 60 years old, suggest age-dependent changes in the myenteric plexus area, ENS ganglion area, percentage of myenteric plexus occupied by ganglia, neurons/mm2, and neuron Feret's diameter. Neuron counting using 3-dimensional images was highly reproducible. High ENS density in neonatal colon allowed reliable neuron counts using 500-µm2 × 500-µm2 regions (36-fold smaller than in adults). Hirschsprung's samples varied 8-fold in proximal margin enteric neuron density and had diverse ENS architecture in resected bowel. CONCLUSIONS: Tissue clearing and 3-dimensional imaging provide more reliable information about ENS structure than tissue sections. ENS structure changes during childhood. Three-dimensional ENS anatomy may provide new insight into human bowel motility disorders, including Hirschsprung's disease.

7.
bioRxiv ; 2024 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-38328115

RESUMO

KRAS is a small GTPase, ubiquitously expressed in mammalian cells, that functions as a molecular switch to regulate cell proliferation and differentiation. Oncogenic mutations that render KRAS constitutively active occur frequently in human cancers. KRAS must localize to the plasma membrane (PM) for biological activity. KRAS PM binding is mediated by interactions of the KRAS membrane anchor with phosphatidylserine (PtdSer), therefore, depleting PM PtdSer content abrogates KRAS PM binding and oncogenic function. From a genome-wide siRNA screen to search for genes that regulate KRAS PM localization, we identified a set of phosphatidylinositol (PI) 3-phosphatase family members: myotubularin-related (MTMR) proteins 2, 3, 4 and 7. Here we show that knockdown of MTMR 2/3/4/7 expression disrupts KRAS PM interactions. The molecular mechanism involves depletion of PM PI 4-phosphate (PI4P) levels, which in turn disrupts the subcellular localization and operation of oxysterol-binding protein related protein (ORP) 5, a PtdSer lipid transfer protein that maintains PM PtdSer content. Concomitantly, silencing MTMR 2/3/4/7 expression elevates PM levels of PI3P and reduces PM and total cellular levels of PtdSer. In summary we propose that the PI 3-phosphatase activity provided by MTMR proteins is required to generate PM PI for the synthesis of PM PI4P, which in turn, promotes the PM localization of PtdSer and KRAS.

8.
Am J Transplant ; 24(3): 419-435, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38295008

RESUMO

There is a critical need for biomarkers of acute cellular rejection (ACR) in organ transplantation. We hypothesized that ACR leads to changes in donor-reactive T cell small extracellular vesicle (sEV) profiles in transplant recipient circulation that match the kinetics of alloreactive T cell activation. In rodent heart transplantation, circulating T cell sEV quantities (P < .0001) and their protein and mRNA cargoes showed time-specific expression of alloreactive and regulatory markers heralding early ACR in allogeneic transplant recipients but not in syngeneic transplant recipients. Next generation sequencing of their microRNA cargoes identified novel candidate biomarkers of ACR, which were validated by stem loop quantitative reverse transcription polymerase chain reaction (n = 10). Circulating T cell sEVs enriched from allogeneic transplant recipients mediated targeted cytotoxicity of donor cardiomyocytes by apoptosis assay (P < .0001). Translation of the concept and EV methodologies to clinical heart transplantation demonstrated similar upregulation of circulating T cell sEV profiles at time points of grade 2 ACR (n = 3 patients). Furthermore, T cell receptor sequencing of T cell sEV mRNA cargo demonstrated expression of T cell clones with intact complementarity determining region 3 signals. These data support the diagnostic potential of T cell sEVs as noninvasive biomarker of ACR and suggest their potential functional roles.


Assuntos
Vesículas Extracelulares , Linfócitos T , Humanos , Biomarcadores , RNA Mensageiro/genética , Aloenxertos
9.
Behav Res Methods ; 56(3): 2064-2082, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37249898

RESUMO

Cardiac measures such as heart rate measurements are important indicators of both physiological and psychological states. However, despite their extraordinary potential, their use is restricted in comparative psychology because traditionally cardiac measures involved the attachment of sensors to the participant's body, which, in the case of undomesticated animals such as nonhuman primates, is usually only possible during anesthesia or after extensive training. Here, we validate and apply a camera-based system that enables contact-free detection of animals' heart rates. The system automatically detects and estimates the cardiac signals from cyclic change in the hue of the facial area of a chimpanzee. In Study 1, we recorded the heart rate of chimpanzees using the new technology, while simultaneously measuring heart rate using classic PPG (photoplethysmography) finger sensors. We found that both methods were in good agreement. In Study 2, we applied our new method to measure chimpanzees' heart rate in response to seeing different types of video scenes (groupmates in an agonistic interaction, conspecific strangers feeding, nature videos, etc.). Heart rates changed during video presentation, depending on the video content: Agonistic interactions and conspecific strangers feeding lead to accelerated heart rate relative to baseline, indicating increased emotional arousal. Nature videos lead to decelerated heart rate relative to baseline, indicating a relaxing effect or heightened attention caused by these stimuli. Our results show that the new contact-free technology can reliably assess the heart rate of unrestrained chimpanzees, and most likely other primates. Furthermore, our technique opens up new avenues of research within comparative psychology and facilitates the health management of captive individuals.


Assuntos
Pan troglodytes , Primatas , Humanos , Animais , Frequência Cardíaca/fisiologia , Emoções , Fotopletismografia/métodos
10.
HLA ; 103(1): e15239, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-37784210

RESUMO

Nonhuman primates are the closest animal models to humans with respect to genetics and physiology. Consequently, a critical component of immunogenetics research relies on drawing inferences from the cynomolgus macaque to inform human trials. Despite the conserved organization of the Major Histocompatibility Complex (MHC) between cynomolgus macaques and humans, MHC genotyping of cynomolgus macaques is challenging due to high rates of copy number variants, duplications, and rearrangements, particularly at the MHC class I loci. Furthermore, the limited availability of commercial reagents specific to cynomolgus macaques that can be used to characterize anti-MHC class I and class II antibody (Ab) specificities in cynomolgus macaques presents a major bottleneck in translational research. Here we successfully characterized cynomolgus macaque Mafa class I and class II serologic specificities in 86 animals originating from various geographical regions using the complement dependent cytotoxicity (CDC) assay with human HLA class I and class II monoclonal antibody (mAb) typing trays. Further, we successfully induced and characterized anti-Mafa class I and class II alloantibody specificity using HLA single antigen bead assays. We also subsequently tracked the alloAb burden in the animals during treatment with anti-B lymphocyte stimulator (BLyS) treatment. Altogether, these methods can be easily used in translational research to serotype MHC class I and class II specificity in macaques, characterize their alloAb specificity, and evaluate the efficacy of novel therapeutic modalities in depleting circulating alloAbs in these animals.


Assuntos
Complexo Principal de Histocompatibilidade , Polimorfismo Genético , Animais , Humanos , Alelos , Antígenos de Histocompatibilidade Classe I/genética , Macaca fascicularis/genética
11.
Cell Rep Med ; 4(12): 101336, 2023 12 19.
Artigo em Inglês | MEDLINE | ID: mdl-38118406

RESUMO

Pre-existing anti-human leukocyte antigen (HLA) allo-antibodies constitute a major barrier to transplantation. Current desensitization approaches fail due to ineffective depletion of allo-specific memory B cells (Bmems) and long-lived plasma cells (LLPCs). We evaluate the efficacy of chimeric antigen receptor (CAR) T cells targeting CD19 and B cell maturation antigen (BCMA) to eliminate allo-antibodies in a skin pre-sensitized murine model of islet allo-transplantation. We find that treatment of allo-sensitized hosts with CAR T cells targeting Bmems and LLPCs eliminates donor-specific allo-antibodies (DSAs) and mitigates hyperacute rejection of subsequent islet allografts. We then assess the clinical efficacy of the CAR T therapy for desensitization in patients with multiple myeloma (MM) with pre-existing HLA allo-antibodies who were treated with the combination of CART-BCMA and CART-19 (ClinicalTrials.gov: NCT03549442) and observe clinically meaningful allo-antibody reduction. These findings provide logical rationale for clinical evaluation of CAR T-based immunotherapy in highly sensitized candidates to promote successful transplantation.


Assuntos
Receptores de Antígenos Quiméricos , Humanos , Animais , Camundongos , Plasmócitos , Antígeno de Maturação de Linfócitos B , Linfócitos T , Imunoterapia , Anticorpos
12.
Phys Rev Lett ; 131(22): 228202, 2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-38101355

RESUMO

Based on a Hamiltonian that incorporates the elastic coupling between a tracer particle and the embedding active viscoelastic biomatter, we derive a generalized non-Markovian Langevin model for the nonequilibrium mechanical tracer response. Our analytical expressions for the frequency-dependent tracer response function and the tracer positional autocorrelation function agree quantitatively with experimental data for red blood cells and actomyosin networks with and without adenosine triphosphate over the entire frequency range and in particular reproduce the low-frequency violation of the fluctuation-dissipation theorem. The viscoelastic power laws, the elastic constants and effective friction coefficients extracted from the experimental data allow straightforward physical interpretation.

13.
Nat Chem Biol ; 2023 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-37945898

RESUMO

After the discovery of insulin, a century ago, extensive work has been done to unravel the molecular network regulating insulin secretion. Here we performed a chemical screen and identified AZD7762, a compound that potentiates glucose-stimulated insulin secretion (GSIS) of a human ß cell line, healthy and type 2 diabetic (T2D) human islets and primary cynomolgus macaque islets. In vivo studies in diabetic mouse models and cynomolgus macaques demonstrated that AZD7762 enhances GSIS and improves glucose tolerance. Furthermore, genetic manipulation confirmed that ablation of CHEK2 in human ß cells results in increased insulin secretion. Consistently, high-fat-diet-fed Chk2-/- mice show elevated insulin secretion and improved glucose clearance. Finally, untargeted metabolic profiling demonstrated the key role of the CHEK2-PP2A-PLK1-G6PD-PPP pathway in insulin secretion. This study successfully identifies a previously unknown insulin secretion regulating pathway that is conserved across rodents, cynomolgus macaques and human ß cells in both healthy and T2D conditions.

14.
Res Sq ; 2023 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-37886586

RESUMO

Genome wide association studies (GWAS) have identified over 100 signals associated with type 1 diabetes (T1D). However, translating any given T1D GWAS signal into mechanistic insights, including putative causal variants and the context (cell type and cell state) in which they function, has been limited. Here, we present a comprehensive multi-omic integrative analysis of single-cell/nucleus resolution profiles of gene expression and chromatin accessibility in healthy and autoantibody+ (AAB+) human islets, as well as islets under multiple T1D stimulatory conditions. We broadly nominate effector cell types for all T1D GWAS signals. We further nominated higher-resolution contexts, including effector cell types, regulatory elements, and genes for three independent T1D risk variants acting through islet cells within the pancreas at the DLK1/MEG3, RASGRP1, and TOX loci. Subsequently, we created isogenic gene knockouts DLK1-/-, RASGRP1-/-, and TOX-/-, and the corresponding regulatory region knockout, RASGRP1Δ, and DLK1Δ hESCs. Loss of RASGRP1 or DLK1, as well as knockout of the regulatory region of RASGRP1 or DLK1, increased ß cell apoptosis. Additionally, pancreatic ß cells derived from isogenic hESCs carrying the risk allele of rs3783355A/A exhibited increased ß cell death. Finally, RNA-seq and ATAC-seq identified five genes upregulated in both RASGRP1-/- and DLK1-/- ß-like cells, four of which are associated with T1D. Together, this work reports an integrative approach for combining single cell multi-omics, GWAS, and isogenic hESC-derived ß-like cells to prioritize the T1D associated signals and their underlying context-specific cell types, genes, SNPs, and regulatory elements, to illuminate biological functions and molecular mechanisms.

15.
Biofabrication ; 16(1)2023 10 20.
Artigo em Inglês | MEDLINE | ID: mdl-37820623

RESUMO

Exploring the pathogenesis of and developing therapies for cholestatic liver diseases such as primary sclerosing cholangitis (PSC) remains challenging, partly due to a paucity ofin vitromodels that capture the complex environments contributing to disease progression and partly due to difficulty in obtaining cholangiocytes. Here we report the development of a human vascularized bile duct-on-a-chip (VBDOC) that uses cholangiocyte organoids derived from normal bile duct tissue and human vascular endothelial cells to model bile ducts and blood vessels structurally and functionally in three dimensions. Cholangiocytes in the duct polarized, formed mature tight junctions and had permeability properties comparable to those measured inex vivosystems. The flow of blood and bile was modeled by perfusion of the cell-lined channels, and cholangiocytes and endothelial cells displayed differential responses to flow. We also showed that the device can be constructed with biliary organoids from cells isolated from both bile duct tissue and the bile of PSC patients. Cholangiocytes in the duct became more inflammatory under the stimulation of IL-17A, which induced peripheral blood mononuclear cells and differentiated Th17 cells to transmigrate across the vascular channel. In sum, this human VBDOC recapitulated the vascular-biliary interface structurally and functionally and represents a novel multicellular platform to study inflammatory and fibrotic cholestatic liver diseases.


Assuntos
Colangite Esclerosante , Hepatopatias , Humanos , Células Endoteliais/patologia , Leucócitos Mononucleares/patologia , Colangite Esclerosante/patologia , Ductos Biliares , Transdução de Sinais , Hepatopatias/patologia
16.
J Hepatol ; 79(6): 1396-1407, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37611641

RESUMO

BACKGROUND & AIMS: Biliary atresia (BA) is an obstructive cholangiopathy that initially affects the extrahepatic bile ducts (EHBDs) of neonates. The etiology is uncertain, but evidence points to a prenatal cause. Fetal tissues have increased levels of hyaluronic acid (HA), which plays an integral role in fetal wound healing. The objective of this study was to determine whether a program of fetal wound healing is part of the response to fetal EHBD injury. METHODS: Mouse, rat, sheep, and human EHBD samples were studied at different developmental time points. Models included a fetal sheep model of prenatal hypoxia, human BA EHBD remnants and liver samples taken at the time of the Kasai procedure, EHBDs isolated from neonatal rats and mice, and spheroids and other models generated from primary neonatal mouse cholangiocytes. RESULTS: A wide layer of high molecular weight HA encircling the lumen was characteristic of the normal perinatal but not adult EHBD. This layer, which was surrounded by collagen, expanded in injured ducts in parallel with extensive peribiliary gland hyperplasia, increased mucus production and elevated serum bilirubin levels. BA EHBD remnants similarly showed increased HA centered around ductular structures compared with age-appropriate controls. High molecular weight HA typical of the fetal/neonatal ducts caused increased cholangiocyte spheroid growth, whereas low molecular weight HA induced abnormal epithelial morphology; low molecular weight HA caused matrix swelling in a bile duct-on-a-chip device. CONCLUSION: The fetal/neonatal EHBD, including in human EHBD remnants from Kasai surgeries, demonstrated an injury response with prolonged high levels of HA typical of fetal wound healing. The expanded peri-luminal HA layer may swell and lead to elevated bilirubin levels and obstruction of the EHBD. IMPACT AND IMPLICATIONS: Biliary atresia is a pediatric cholangiopathy associated with high morbidity and mortality rates; although multiple etiologies have been proposed, the fetal response to bile duct damage is largely unknown. This study explores the fetal pathogenesis after extrahepatic bile duct damage, thereby opening a completely new avenue to study therapeutic targets in the context of biliary atresia.


Assuntos
Ductos Biliares Extra-Hepáticos , Atresia Biliar , Humanos , Animais , Camundongos , Ratos , Criança , Ovinos , Atresia Biliar/patologia , Ductos Biliares Extra-Hepáticos/patologia , Feto/patologia , Cicatrização , Bilirrubina
18.
Nat Cell Biol ; 25(4): 565-578, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36928765

RESUMO

The pancreatic islets are composed of discrete hormone-producing cells that orchestrate systemic glucose homeostasis. Here we identify subsets of beta cells using a single-cell transcriptomic approach. One subset of beta cells marked by high CD63 expression is enriched for the expression of mitochondrial metabolism genes and exhibits higher mitochondrial respiration compared with CD63lo beta cells. Human and murine pseudo-islets derived from CD63hi beta cells demonstrate enhanced glucose-stimulated insulin secretion compared with pseudo-islets from CD63lo beta cells. We show that CD63hi beta cells are diminished in mouse models of and in humans with type 2 diabetes. Finally, transplantation of pseudo-islets generated from CD63hi but not CD63lo beta cells into diabetic mice restores glucose homeostasis. These findings suggest that loss of a specific subset of beta cells may lead to diabetes. Strategies to reconstitute or maintain CD63hi beta cells may represent a potential anti-diabetic therapy.


Assuntos
Diabetes Mellitus Experimental , Diabetes Mellitus Tipo 2 , Células Secretoras de Insulina , Humanos , Camundongos , Animais , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Secreção de Insulina , Insulina/metabolismo , Diabetes Mellitus Experimental/metabolismo , Células Secretoras de Insulina/metabolismo , Glucose/metabolismo
19.
Phys Rev E ; 107(2-1): 024602, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36932605

RESUMO

We study translocation of a flexible polymer chain through a membrane pore under the influence of active forces and steric exclusion using Langevin dynamics simulations within a minimal two-dimensional model. The active forces on the polymer are imparted by nonchiral and chiral active particles that are introduced on one side or both sides of a rigid membrane positioned across the midline of a confining box. We show that the polymer can translocate through the pore to either side of the dividing membrane in the absence of external forcing. Translocation of the polymer to a given side of the membrane is driven (hindered) by an effective pulling (pushing) exerted by the active particles that are present on that side. The effective pulling results from accumulation of active particles around the polymer. This crowding effect signifies persistent motion of active particles causing prolonged detention times for them close to the confining walls and the polymer. The effective pushing that hinders the translocation, on the other hand, results from steric collisions that occur between the polymer and active particles. As a result of the competition between these effective forces, we find a transition between two rectified cis-to-trans and trans-to-cis translocation regimes. This transition is identified by a sharp peak in the average translocation time. The effects of active particles on the transition is studied by analyzing how the translocation peak is regulated by the activity (self-propulsion) strength of these particles, their area fraction, and chirality strength.

20.
bioRxiv ; 2023 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-36711819

RESUMO

Type 1 and Type 2 diabetes are distinct genetic diseases of the pancreas which are defined by the abnormal level of blood glucose. Understanding the initial molecular perturbations that occur during the pathogenesis of diabetes is of critical importance in understanding these disorders. The inability to biopsy the human pancreas of living donors hampers insights into early detection, as the majority of diabetes studies have been performed on peripheral leukocytes from the blood, which is not the site of pathogenesis. Therefore, efforts have been made by various teams including the Human Pancreas Analysis Program (HPAP) to collect pancreatic tissues from deceased organ donors with different clinical phenotypes. HPAP is designed to define the molecular pathogenesis of islet dysfunction by generating detailed datasets of functional, cellular, and molecular information in pancreatic tissues of clinically well-defined organ donors with Type 1 and Type 2 diabetes. Moreover, data generated by HPAP continously become available through a centralized database, PANC-DB, thus enabling the diabetes research community to access these multi-dimensional data prepublication. Here, we present the computational workflow for single-cell RNA-seq data analysis of 258,379 high-quality cells from the pancreatic islets of 67 human donors generated by HPAP, the largest existing scRNA-seq dataset of human pancreatic tissues. We report various computational steps including preprocessing, doublet removal, clustering and cell type annotation across single-cell RNA-seq data from islets of four distintct classes of organ donors, i.e. non-diabetic control, autoantibody positive but normoglycemic, Type 1 diabetic, and Type 2 diabetic individuals. Moreover, we present an interactive tool, called CellxGene developed by the Chan Zuckerberg initiative, to navigate these high-dimensional datasets. Our data and interactive tools provide a reliable reference for singlecell pancreatic islet biology studies, especially diabetes-related conditions.

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