Project description:As a group, fibroproliferative disorders of the lung, liver, kidney, heart, vasculature and integument are common, progressive and refractory to therapy. They can emerge following toxic insults, but are frequently idiopathic. Their enigmatic propensity to resist therapy and progress to organ failure has focused attention on the myofibroblast – the primary effector of the fibroproliferative response. A central unanswered question is whether these myofibroblasts have acquired a distinct pathological phenotype - or whether they are normal myofibroblasts with a pathological phenotype that depends upon residing in a sea of pro-fibrotic cytokines and an abnormal extracellular matrix. Using a systems approach to study this question in a prototype fibrotic disease, Idiopathic Pulmonary Fibrosis (IPF); here we show organized changes in the gene expression pathway of primary lung myofibroblasts that persist for up to 9 sub-cultivations in vitro. When comparing IPF and control myofibroblasts in a 3-dimensional type I collagen matrix, more genes differed at the level of ribosome recruitment than at the level of transcript abundance, indicating pathological translational control as a major characteristic of IPF myofibroblasts. To determine the effect of matrix state on translational control, myofibroblasts were permitted to contract the matrix. Ribosome recruitment in control myofibroblasts was relatively stable. In contrast, IPF cells manifested large alterations in the ribosome recruitment pattern. Pathological studies suggest an epithelial origin for IPF myofibroblasts through the epithelial to mesenchymal transition (EMT). In accord with this, we found systems-level indications for TGF?b -driven EMT as one source of IPF myofibroblasts. Keywords: cell type comparison Comparison of lung myofibroblasts from patients with Idiopatic Pulmonary Fibrosis (IPF, 6 donors) to control (6 donors) in contractile and non-contractile matrices using both total and polyribosomal RNA
Project description:Fibrotic disease is caused by persistently activated fibroblasts, known as myofibroblasts, that continuously deposit extracellular matrix and fail to de-activate after injury resolution. There are currently no treatments for fibrotic disease; our study addresses the mechanisms whereby myofibroblasts persist in fibrotic tissues such as diseased cardiac valves. We exploit photo-softening hydrogels as synthetic valve tissue mimics and valve fibroblasts as a model to study how stiffness controls pathological myofibroblast activation and their persistence. We show that persistent myofibroblasts have condensed chromatin structure with genome-wide alterations and that this is associated with stabilization of the actin cytoskeleton. Disconnecting the nucleus from the cytoskeleton prevents chromatin condensation and myofibroblast persistence. Notably, myofibroblasts in patients with aortic valve stenosis display a condensed chromatin structure compared to myofibroblasts in a healthy patient, similar to the difference observed between cultured persistent myofibroblasts and transient myofibroblasts. Collectively, our results reveal that nuclear mechanosensing leads to distinct chromatin signatures in persistent myofibroblasts and that this novel cellular mechanism is likely relevant to human fibrotic disease.
Project description:As a group, fibroproliferative disorders of the lung, liver, kidney, heart, vasculature and integument are common, progressive and refractory to therapy. They can emerge following toxic insults, but are frequently idiopathic. Their enigmatic propensity to resist therapy and progress to organ failure has focused attention on the myofibroblast – the primary effector of the fibroproliferative response. A central unanswered question is whether these myofibroblasts have acquired a distinct pathological phenotype - or whether they are normal myofibroblasts with a pathological phenotype that depends upon residing in a sea of pro-fibrotic cytokines and an abnormal extracellular matrix. Using a systems approach to study this question in a prototype fibrotic disease, Idiopathic Pulmonary Fibrosis (IPF); here we show organized changes in the gene expression pathway of primary lung myofibroblasts that persist for up to 9 sub-cultivations in vitro. When comparing IPF and control myofibroblasts in a 3-dimensional type I collagen matrix, more genes differed at the level of ribosome recruitment than at the level of transcript abundance, indicating pathological translational control as a major characteristic of IPF myofibroblasts. To determine the effect of matrix state on translational control, myofibroblasts were permitted to contract the matrix. Ribosome recruitment in control myofibroblasts was relatively stable. In contrast, IPF cells manifested large alterations in the ribosome recruitment pattern. Pathological studies suggest an epithelial origin for IPF myofibroblasts through the epithelial to mesenchymal transition (EMT). In accord with this, we found systems-level indications for TGF-beta -driven EMT as one source of IPF myofibroblasts. Keywords: cell type comparison
Project description:Hepatic stellate cells are the primary cell type responsible for development of fibrosis in chronic liver disease. We used directional RNA sequencing (RNA-seq) and chromatin immunoprecipitation and sequencing (ChIP-seq) to identify the lncRNAs expressed in human HSCs. We also identified the lncRNAs that change in expression with differentiation of nonfibrotic quiescent HSCs into fibrotic HSC myofibroblasts and those that are regulated by TGF-beta signaling. ChIP-seq was also performed to identify DNA regions occupied by H3K27ac to define super-enhancers in HSC myofibroblasts. This study identified lncRNAs expressed HSCs that may regulate fibrosis. Analysis of genome-wide lncRNA expression using RNA-seq and ChiP-seq in human HSCs under four different conditions
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.
Project description:Here, we investigate the role of enhancers in myofibroblasts, a cell type that dominates the pathogenesis and progression of tissue fibrosis. We reveal that bromodomain and extra-terminal family members (BETs), an important group of epigenetic readers, are critical for super-enhancer-mediated pro-fibrotic gene expression in hepatic stellate cells (HSCs, lipid-containing liver-specific pericytes), upon activation during liver fibrogenesis give rise to myofibroblasts2-4. We observe significantly enriched localization of BETs to hundreds of super-enhancers associated with genes involved in multiple pro-fibrotic pathways. This unique loading pattern consequentially serves as a molecular mechanism by which BETs modulate pro-fibrotic gene expression in myofibroblasts. Strikingly, suppression of BET-enhancer interaction using small-molecule inhibitors such as JQ1 dramatically blocks activation of HSCs into myofibroblasts and significantly compromises the proliferation of activated HSCs. Identification of BRD2, BRD3, BRD4, PolII, PolIIs2p and PolIIs5p binding sites in human stellate LX2 cells that were treated with DMSO (0.1%) or JQ1 (500nM) for 16 hrs.
Project description:As the evolution of miRNA genes has been found to be one of the important factors in formation of the modern type of man, we performed a comparative analysis of the evolution of miRNA genes in two archaic hominines, Homo sapiens neanderthalensis and Homo sapiens denisova, and elucidated the expression of their target mRNAs in bain.A comparative analysis of the genomes of primates, including species in the genus Homo, identified a group of miRNA genes having fixed substitutions with important implications for the evolution of Homo sapiens neanderthalensis and Homo sapiens denisova. The mRNAs targeted by miRNAs with mutations specific for Homo sapiens denisova exhibited enhanced expression during postnatal brain development in modern humans. By contrast, the expression of mRNAs targeted by miRNAs bearing variations specific for Homo sapiens neanderthalensis was shown to be enhanced in prenatal brain development.Our results highlight the importance of changes in miRNA gene sequences in the course of Homo sapiens denisova and Homo sapiens neanderthalensis evolution. The genetic alterations of miRNAs regulating the spatiotemporal expression of multiple genes in the prenatal and postnatal brain may contribute to the progressive evolution of brain function, which is consistent with the observations of fine technical and typological properties of tools and decorative items reported from archaeological Denisovan sites. The data also suggest that differential spatial-temporal regulation of gene products promoted by the subspecies-specific mutations in the miRNA genes might have occurred in the brains of Homo sapiens denisova and Homo sapiens neanderthalensis, potentially contributing to the cultural differences between these two archaic hominines.
Project description:PurposeWe investigated the evidence of recent positive selection in the human phototransduction system at single nucleotide polymorphism (SNP) and gene level.MethodsSNP genotyping data from the International HapMap Project for European, Eastern Asian, and African populations was used to discover differences in haplotype length and allele frequency between these populations. Numeric selection metrics were computed for each SNP and aggregated into gene-level metrics to measure evidence of recent positive selection. The level of recent positive selection in phototransduction genes was evaluated and compared to a set of genes shown previously to be under recent selection, and a set of highly conserved genes as positive and negative controls, respectively.ResultsSix of 20 phototransduction genes evaluated had gene-level selection metrics above the 90th percentile: RGS9, GNB1, RHO, PDE6G, GNAT1, and SLC24A1. The selection signal across these genes was found to be of similar magnitude to the positive control genes and much greater than the negative control genes.ConclusionsThere is evidence for selective pressure in the genes involved in retinal phototransduction, and traces of this selective pressure can be demonstrated using SNP-level and gene-level metrics of allelic variation. We hypothesize that the selective pressure on these genes was related to their role in low light vision and retinal adaptation to ambient light changes. Uncovering the underlying genetics of evolutionary adaptations in phototransduction not only allows greater understanding of vision and visual diseases, but also the development of patient-specific diagnostic and intervention strategies.
Project description:Cortical thickness has been investigated since the beginning of the 20th century, but we do not know how similar the cortical thickness profiles among humans are. In this study, the local similarity of cortical thickness profiles was investigated using sliding window methods. Here, we show that approximately 5% of the cortical thickness profiles are similarly expressed among humans while 45% of the cortical thickness profiles show a high level of heterogeneity. Therefore, heterogeneity is the rule, not the exception. Cortical thickness profiles of somatosensory homunculi and the anterior insula are consistent among humans, while the cortical thickness profiles of the motor homunculus are more variable. Cortical thickness profiles of homunculi that code for muscle position and skin stimulation are highly similar among humans despite large differences in sex, education, and age. This finding suggests that the structure of these cortices remains well preserved over a lifetime. Our observations possibly relativize opinions on cortical plasticity.