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Haghani, A.

Publications and source records attributed to Haghani, A..

At least 19 recordsLinked to original sources

Protocol for Single-Cell Patch-Proteomics: identify specific proteins associated with electrophysiological properties from individual neurons

Single-cell patch-proteomics is a novel and powerful technique combining electrophysiological and quantitative proteomic characterization from individually sampled neurons. Following whole-cell patch clamp characterization of neuronal excitability, we collect intracellular contents and, using the latest advancements in Liquid Chromatography and Mass Spectrometry, identify and quantify peptides and their corresponding proteins. By cell-matched one-to-one associations between electrophysiological properties and protein abundance, this approach provides a means to elucidate molecular mechanisms of neuronal function on individual neuron basis.

neuroscience↗

Transplanted hearts assimilate the recipient's biological age

Background. Despite the growing demand for transplantation, a shortage of donor organs persists, limiting access to this lifesaving procedure. To meet the increasing demand, organs are frequently transplanted across an age discrepancy between donor and recipients. Methods. We delineated biological age dynamics in heterochronic heart transplants performed in both mice and patients. We carried out multiomic profiling and applied advanced biomarkers of aging to understand the interactions between the transplanted organ and the host. Results. We show that the biological age of experimental heart transplants rapidly assimilates the age of recipients. Interestingly, this effect was limited to the grafted tissue without reciprocal effects on systemic biological age of the recipient. These effects were confirmed at the level of DNA methylation and gene expression. Extending our findings clinically using both omics and functional analyses, we show that the biological age of heterochronically transplanted hearts is strongly associated with the age of the recipient, rather than the donor, confirming the clinical relevance of our experimental findings. Conclusions. These data identify the systemic environment as a driving force on tissue biological age. The rejuvenation of older organs in young recipients suggests novel approaches to organ allocation that may expand the pool of transplantable organs.

systems biology↗

Single-cell proteomic maps of human induced pluripotent stem cells and their differentiation into motor neurons

The majority of single cell-studies use RNA to identify the cell state. However, many RNAs are transient and decrease in response to elevated protein to control homeostasis. Thus, final cell states are largely defined by their unique and dynamic protein composition not RNA. Here a single-cell proteomics approach was used to identify the proteomic profile of human induced pluripotent stem cells (iPSCs) before and during their in vitro differentiation to motor neurons. By measuring up to 1000 proteins in each cell, novel clusters of growing iPSCs could be characterized along with a new proteomic pathway that defines motor neuron development. Interestingly, there was a dynamic and cell type-specific discordance between the protein levels and their corresponding messenger RNAs. This lays the foundation for drawing new single-cell proteomic maps of developing human tissues. IN BRIEFIn this article, we report the first single-cell proteomic maps of induced pluripotent stem cells (iPSCs) and their differentiation into motor neurons (MNs). By identifying proteomes of individual cells, we resolve iPSC and MN states, their proteomic, metabolomic and organellar heterogeneity. We show considerable, stage-specific discordance between the transcriptome and the proteome in differentiated neurons.

neuroscience↗

Extended NGN2 Expression in iPSCs Dramatically Enhances Purity of Neuronal Cultures

iPSC-derived neuronal cultures can provide valuable insights into the pathogenesis of neurological disease. However, single-cell iPSC clones expressing NGN2 and mCherry exhibit spontaneous loss of mCherry fluorescence, raising questions about the homogeneity of neurons derived from what appear to be heterogeneous iPSCs. We find that mCherry silencing does not influence iNeurons with two lines of evidence. First, using single-cell proteomics, we found that spontaneous mCherry silencing does not drive heterogeneity in iPSCs. Second, bulk proteomics and immunofluorescence analysis indicated that iNeurons from iPSCs expressing or lacking mCherry both resemble cortical glutamatergic neurons. The primary confounding factor in iNeuron generation was that suboptimal neuronal conversion led to cell aggregates comprised of actively proliferating neuronal progenitor cells and astrocytes as the culture developed. Our results indicate that extended NGN2 dosage substantially improves neuron purity. HighlightsO_LIEF1-mCherry undergoes spontaneous silencing at the AAVS1 locus C_LIO_LISingle-cell proteomics reveals heterogeneity in edited iPSCs independent of mCherry silencing C_LIO_LImCherry silencing has minimal impact on NGN2-mediated neuronal differentiation. C_LIO_LIExtended NGN2 induction produces more homogenous neuronal cultures C_LI eTOC blurbExpression of a mCherry reporter under the EF1 promoter and integrated into the AAVS1 locus is silenced in undifferentiated iPSCs, whereas CAG-driven rtTA3G remains active for NGN2-induced neuronal differentiation. Optimizing NGN2 induction in iPSC cultures is crucial for generating homogeneous neuronal cultures, as suboptimal conditions result in heterogeneous populations enriched with neural progenitor cells (NPCs) and astrocytes, and a disrupted neuronal organization.

biochemistry↗

Development and Clinical Evaluation of a Multiplexed Health Surveillance Panel Using Ultra High-Throughput PRM-MS in an Inflammatory Bowel Disease Cohort.

Despite advances in clinical proteomics, translating protein biomarker discoveries into clinical use remains challenging due to the technical complexity of the validation process. Targeted MS-based proteomics approaches such as parallel reaction monitoring (PRM) offer sensitive and specific assays for biomarker translation. In this study, we developed a multiplex PRM assay using the Stellar mass spectrometry platform to quantify 57 plasma proteins, including 21 FDA-approved proteins. Loading curves (11-points) were performed at 4 sample throughputs (100, 144, 180, and 300 samples per day) using independent, optimized, and scheduled PRM methods. Following optimization, an inflammatory bowel disease (IBD) cohort of plasma samples (493 IBD, 509 matched controls) was analyzed at a throughput of 180 SPD. To monitor system performance, the study also included 1,000 additional injections for system suitability tests, low-, middle-, and high-quality controls, washes, and blanks. Using this approach, we observed high quantifiability (linearity, sensitivity, reproducibility) in the PRM assay and consistent in data acquisition across a large cohort. We also validated the candidate IBD markers, C-reactive protein and orosomucoid protein, identified in a recent discovery experiment.

biochemistry↗

Single Cell Proteomics Reveals Novel Cell Phenotypes in Marfan Mouse Aneurysm

BackgroundSingle-cell omics technology is a powerful tool in biomedical research. However, single cell proteomics has lagged due to an inability to amplify peptides in a similar fashion to nucleotide strings. Single cell proteomics is important because proteins are the main functional unit in cells, and they often poorly correlate with mRNA quantities. In this paper we describe the first single cell proteomic analysis of complex tissue, comparing aneurysmal and normal mouse aorta from males and females. We also compare and integrate our single cell proteomic profiles with a matching single cell transcriptomics dataset. MethodsWe compared single cell proteomes between male and female, wild-type and Fbn1C1041G/+ Marfan mice (N=3 per group). Individual cells from mouse aortic root single cell suspensions were deposited in 384 well plates and subjected to ultra-sensitive nanoflow liquid chromatography-ion mobility-time of flight-mass spectrometry. The data were analyzed with leiden clustering to identify cell types. Statistical analyses were performed to detect differential proteins within cell types and multi-omics analysis integrated single cell proteomics with published single cell RNA-seq. ResultsWe identified all major aortic cell types including 7 distinct smooth muscle cell subtypes. The proportion of these cells varied based on sex and the Fbn1C1041G/+ genotype. Differentially expressed proteins between male and female in addition to wild-type and Marfan samples uncovered enhanced endothelial to mesenchymal transition patterns in endothelial cells from male Marfan mice. Comparisons between single cell RNA and single cell proteomic profiles showed similarities in major subtypes but not smooth muscle cell subtypes. Multi-omics analysis of these two single cell platforms demonstrated a potential novel role for smooth muscle cell derived angiotensin signaling in the Marfan phenotype. ConclusionsSingle cell proteomics identified new subpopulations of vascular smooth muscles cells and novel cell type specific protein signatures related to sex differences and aneurysm formation. AbbreviationsNext generation sequencing (NGS), Mass spectrometer (MS), Single cell proteomics by Mass Spectrometry (ScOPE-MS), Marfans syndrome (MFS), Fibrillin 1 (FBN1), Transforming growth factor {beta} (TGF{beta}), Smooth muscle cell (SMC), Single cell proteomic (scProteomic), Differentially expressed proteins (DEPs), Wild-type (WT), Hanks balanced salt solution (HBSS), Fetal bovine serum (FBS), Dulbeccos Modified Eagle Medium (DMEM), Data-independent acquisition parallel accumulation-serial fragmentation (DIA-PASEF), Magnetic assisted cell sorted (MACS), Single Cell Analysis in Python (Scanpy), Kyoto Encyclopedia of Genes and Genomes (KEGG), Principal component analysis (PCA), Uniform manifold projection (UMAP), Single cell transcriptomic (scTranscriptomic), Smoothelin (Smtn), Transgelin (Tagln), Myosin heavy chain 11 (Myh11), Platelet endothelial cell adhesion molecule 1 (Pecam1), Dipeptidase 1 (Dpep1), Uncoupling protein 1 (Ucp1), Low-density lipoprotein receptor-related protein (Lrp1), DNA ligase 3 (Lig3), Capsaicin channel transient receptor potential vanilloid 1 (Trpv1), Endothelial to mesenchymal transition (endMT), Intercellular adhesion molecule 1 (Icam1), Intercellular adhesion molecule 2 (Icam2), Endothelial cell-selective adhesion molecule (Esam), Calponin 1 (Cnn1), Vimentin (Vim), Zinc finger E-box-binding homeobox 1 (Zeb1), Snail family transcriptional repressor 1 (Snai1), Tropomyosin alpha-4 chain (Tpm4), Angiotensin converting enzyme (Ace)

systems biology↗

Axolotl epigenetic clocks offer insights into the nature of negligible senescence

Renowned for their regenerative abilities, axolotls also exhibit exceptional longevity, resistance to age-related diseases and apparent lack of physiological declines through lifespan, and have thus been considered organisms of negligible senescence. Whether axolotls display epigenetic hallmarks of ageing remains unknown. Here, we probe the axolotl DNA methylome throughout lifespan and present its first epigenetic clocks. Both at tissue-specific or pan-tissue levels, the clocks are biphasic, capable of predicting age during early life but not for the rest of its lifespan. We show that axolotls exhibit evolutionarily conserved features of epigenetic ageing during early life, yet their methylome is remarkably stable across lifespan, including at Polycomb Repressive Complex 2 (PRC2) target sites, suggesting that this species deviates from known patterns of epigenetic ageing. This study provides molecular insights into negligible senescence and furthers our understanding of ageing dynamics in animals capable of extreme regeneration.

developmental biology↗

Cell Storage Conditions Impact Single-Cell Proteomic Landscapes

Single-cell transcriptomics (SCT) has revolutionized our understanding of cellular heterogeneity, yet the emergence of single-cell proteomics (SCP) promises a more functional view of cellular dynamics. A challenge is that not all mass spectrometry facilities can perform SCP, and not all labs have access to cell sorting equipment required for SCP, which together motivate an interest in sending bulk cell samples through the mail for sorting and SCP analysis. Shipping requires cell storage, which has an unknown impact on SCP results. This study investigates the impact of cell storage conditions on the proteomic landscape at the single-cell level utilizing a Data-Independent Acquisition (DIA) coupled with Parallel Accumulation Serial Fragmentation (diaPASEF). Three storage conditions were compared in 293T cells: (1) 37{degrees}C (control), (2) 4{degrees}C overnight, and (3) - 80{degrees}C storage followed by liquid nitrogen preservation. Either cold or frozen storage induced significant alterations in cell diameter, elongation, and proteome composition. By elucidating how cell storage conditions alter cellular morphology and proteome profiles, this study contributes foundational technical information about SCP sample preparation and data quality.

cell biology↗

Loss of H3K9 trimethylation leads to premature aging

Aging is the major risk factor for most human diseases and represents a major socio-economical challenge for modern societies. Despite its importance, the process of aging remains poorly understood. Epigenetic dysregulation has been proposed as a key driver of the aging process. Modifications in transcriptional networks and chromatin structure might be central to age-related functional decline. A prevalent feature described during aging is the overall reduction in heterochromatin, specifically marked by the loss of repressive histone modification, Histone 3 lysine 9 trimethylation (H3K9me3). However, the role of H3K9me3 in aging, especially in mammals, remains unclear. Here we show using a novel mouse strain, (TKOc), carrying a triple knockout of three methyltransferases responsible for H3K9me3 deposition, that the inducible loss of H3K9me3 in adulthood results in premature aging. TKOc mice exhibit reduced lifespan, lower body weight, increased frailty index, multi-organ degeneration, transcriptional changes with significant upregulation of transposable elements, and accelerated epigenetic age. Our data strongly supports the concept that the loss of epigenetic information directly drives the aging process. These findings reveal the importance of epigenetic regulation in aging and suggest that interventions targeting epigenetic modifications could potentially slow down or reverse age-related decline. Understanding the molecular mechanisms underlying the process of aging will be crucial for developing novel therapeutic strategies that can delay the onset of age-associated diseases and preserve human health at old age specially in rapidly aging societies.

physiology↗

Epigenetic predictors of species maximum lifespan and other life history traits in mammals

Maximum lifespan is an intrinsic characteristic of a biological species and is defined as the longest time an individual of a species has been reported to survive. By analyzing 15K samples derived from 348 mammalian species representing 25 taxonomic orders we previously identified CpG methylation sites associated with maximum lifespan. Here we present accurate DNA methylation-based (DNAm) predictors of maximum lifespan (r=0.89), average gestation time (r=0.96), and age at sexual maturity (r=0.85). Our DNAm maximum lifespan predictor indicates a potential innate longevity advantage for females over males in 17 mammalian species such as humans, red deer, and cattle. The DNAm maximum lifespan predictions do not vary significantly by caloric restriction and partial reprogramming. Genetic disruptions in the somatotropic axis, which includes growth hormone, IGF-1, and their related receptors, have an impact on DNAm maximum lifespan only in select mouse tissues. Cancer mortality rates in major mammalian orders show no correlation with our epigenetic estimates of life history traits. The DNAm maximum lifespan predictor does not detect variation in lifespan between individuals of the same species, such as between the breeds of dogs. We also present the first prototypes of accurate pan mammalian DNAm predictors of sex and tissue type. Collectively, our findings indicate that maximum lifespan is determined, at least in part, by an epigenetic signature that is an intrinsic property of each species and is distinct from the signatures that relate to individual lifespan, which is unaffected by interventions influencing the mortality risk of individuals.

evolutionary biology↗

COGNITIVE REJUVENATION IN OLD RATS BY HIPPOCAMPAL OSKM GENE THERAPY

Impaired performance in spatial learning and memory during aging in rats is associated with morphological and molecular changes in the brain, particularly in the hippocampus. Here, we assessed the cognitive performance of young (3.5 mo.) untreated rats and old (25.3 mo.) treated and control rats. Treatment was carried out by intrahippocampal injection of an adenovector that carries the GFP reporter gene as well as the 4 Yamanaka genes. Learning and spatial memory performance were assessed by means of the Barnes maze test. The learning performance of the OSKM-treated old rats was significantly improved compared to that of the control old counterparts. A marginal (P=0.06) improvement in the spatial memory was recorded in the treated versus control old rats. OSKM gene expression induced no pathological changes in the brain. The morphology and number of hippocampal cell populations like astrocytes and mature neurons did not show any changes with the treatment in the old rats as compared with the control old counterparts. The rat pan tissue DNAm age marker revealed that old OSKM gene-treated rats show a trend towards a decrease in epigenetic age. The Limma package was used to assess differential methylation by fitting linear models to the methylation data for specific group comparisons. Comparison of differential methylation between old treated and old control hippocampal DNA samples identified 671 differentially methylated CpGs probes (DPMs) in the DNA of OSKM-treated hippocampi (p<0.05). Assessment of the DPMs in old versus young controls revealed the presence of 1,279 hypomethylated CpGs near the promoter regions in young hippocampi (versus old controls) and 914 hypermethylated CpGs near the promoter in young hippocampi compared to old control hippocampi. We found a subset of 174 hypomethylated CpGs in the hippocampal DNA from old OSKM rats and young controls both compared with old control hippocampi. This means that in the hippocampal DNA there is a common set of CpGs which are hypermethylated during aging and are demethylated by the OSKM genes. This observation suggested that in these 174 CpGs the hypermethylation induced by aging is reversed by the demethylation effect of the OSKM genes on the same 174 CpGs. This observation can be interpreted as a rejuvenation effect of the OSKM genes of the old hippocampal methylome. Our results extend to the rat the evidence that viral vector-mediated delivery of the Yamanaka genes in the brain has strong regenerative effects without adverse side effects.

neuroscience↗

Fundamental equations linking methylation dynamics to maximum lifespan in mammals

We establish the mathematical foundation that links the rate of change in any molecular biomarker to species lifespan. Specifically, we propose a robust approach that identifies the strong inverse relationship for certain biomarkers using two comprehensive methylation datasets. After examining 54 chromatin states, we found the rates of change of CpG sites in bivalent chromatin states are negatively associated to the lifespans of 90 dog breeds in the first dataset, and the discoveries are further strengthened with 125 mammalian species in the second dataset. Our research leads to three key findings: First, a reciprocal relationship exists between the average rate of methylation change (AROCM) in bivalent promoter regions and maximum lifespan: AROCM {propto} 1/MaxLifespan. Second, the correlation between age and average methylation bears no relation to maximum lifespan, Cor(Methly,Age) {perp} MaxLifespan. Third, the rate of methylation change in young animals is related to that in old animals: Young animals AROCM {propto} Old AROCM. These findings hinge on the chromatin context, as different results emerge when defining AROCM using different chromatin states. Our analytical framework is versatile and readily extendable to a broad range of other molecular assessments. Overall, our study demonstrates that epigenetic aging rates in specific chromatin states exhibit an inverse relationship with maximum lifespan in mammals.

evolutionary biology↗

Initiation phase cellular reprogramming ameliorates DNA damage in the ERCC1 mouse model of premature aging.

Unlike aged somatic cells, which exhibit a decline in molecular fidelity and eventually reach a state of replicative senescence, pluripotent stem cells can indefinitely replenish themselves while retaining full homeostatic capacity. The conferment of beneficial-pluripotency related traits via in vivo partial cellular reprogramming (IVPR) significantly extends lifespan and restores aging phenotypes in mouse models. Although the phases of cellular reprogramming are well characterized, details of the rejuvenation processes are poorly defined. To understand whether epigenetic reprogramming can ameliorate DNA damage, we created reprogrammable accelerated aging mouse model with an ERCC1 mutation. Importantly, using enhanced partial reprogramming by combining small molecules with the Yamanaka factors, we observed potent reversion of DNA damage, significant upregulation of multiple DNA damage repair processes, and restoration of the epigenetic clock. In addition, we present evidence that pharmacological inhibition of ALK5 and ALK2 receptors in TGFb pathway is able to phenocopy some benefits including epigenetic clock restoration suggesting a role in the mechanism of rejuvenation by partial reprogramming.

cell biology↗

Pleiotropic Influence of DNA Methylation QTLs on physiological and aging traits

DNA methylation is influenced by genetic and non-genetic factors. Here, we chart quantitative trait loci (QTLs) that modulate levels of methylation at highly conserved CpGs using liver methylome data from mouse strains belonging to the BXD Family. A regulatory hotspot on chromosome 5 had the highest density of trans-acting methylation QTLs (trans-meQTLs) associated with multiple distant CpGs. We refer to this locus as meQTL.5a. The trans-modulated CpGs showed age-dependent changes, and were enriched in developmental genes, including several members of the MODY pathway (maturity onset diabetes of the young). The joint modulation by genotype and aging resulted in a more "aged methylome" for BXD strains that inherited the DBA/2J parental allele at meQTL.5a. Further, several gene expression traits, body weight, and lipid levels mapped to meQTL.5a, and there was a modest linkage with lifespan. DNA binding motif and protein-protein interaction enrichment analysis identified the hepatic nuclear factor, Hnf1a (MODY3 gene in humans), as a strong candidate. The pleiotropic effects of meQTL.5a could contribute to variation in body size and metabolic traits, and influence CpG methylation and epigenetic aging that could have an impact on lifespan.

genomics↗

Complete Workflow for High Throughput Human Single Skeletal Muscle Fiber Proteomics

Skeletal muscle is a major regulatory tissue of whole-body metabolism and is composed of a diverse mixture of cell (fiber) types. Aging and several diseases differentially affect the various fiber types, and therefore, investigating the changes in the proteome in a fiber-type specific manner is essential. Recent breakthroughs in isolated single muscle fiber proteomics have started to reveal heterogeneity among fibers. However, existing procedures are slow and laborious requiring two hours of mass spectrometry time per single muscle fiber; 50 fibers would take approximately four days to analyze. Thus, to capture the high variability in fibers both within and between individuals requires advancements in high throughput single muscle fiber proteomics. Here we use a single cell proteomics method to enable quantification of single muscle fiber proteomes in 15 minutes total instrument time. As proof of concept, we present data from 53 isolated skeletal muscle fibers obtained from two healthy individuals analyzed in 13.25 hours. Adapting single cell data analysis techniques to integrate the data, we can reliably separate type 1 and 2A fibers. Sixty-five proteins were statistically different between clusters indicating alteration of proteins involved in fatty acid oxidation, muscle structure and regulation. Our results indicate that this method is significantly faster than prior single fiber methods in both data collection and sample preparation while maintaining sufficient proteome depth. We anticipate this assay will enable future studies of single muscle fibers across hundreds of individuals, which has not been possible previously due to limitations in throughput.

biochemistry↗

High Throughput Proteomic Analysis of Heterogeneous Cell Populations with NanoDTSC

Identification and proteomic characterization of rare cell types within complex organ derived cell mixtures is best accomplished by label-free quantitative mass spectrometry. High throughput is required to rapidly survey hundreds to thousands of individual cells to adequately represent rare populations. Here we present parallelized nanoflow dual-trap single-column liquid chromatography (nanoDTSC) operating at 15 minutes of total run time per cell with peptides quantified over 11.5 minutes using standard commercial components, thus offering an accessible and efficient LC solution to analyze 96 single-cells per day. At this throughput, nanoDTSC quantified over 1,000 proteins in individual cardiomyocytes and heterogenous populations of single cells from aorta. For Table of Contents Only O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=113 SRC="FIGDIR/small/522908v4_ufig1.gif" ALT="Figure 1"> View larger version (33K): org.highwire.dtl.DTLVardef@352d49org.highwire.dtl.DTLVardef@1304d2corg.highwire.dtl.DTLVardef@1a9df5org.highwire.dtl.DTLVardef@1785464_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗

ERCC1 mice, unlike other premature aging models, display accelerated epigenetic age

Over the last decades, several premature aging mouse models have been developed to study aging and identify interventions that can delay age-related diseases. Yet, it is still unclear whether these models truly recapitulate natural aging. Here, we analyzed DNA methylation in multiple tissues of four previously reported mouse models of premature aging (ERCC1, LAKI, POLG and XPG). We estimated DNA methylation (DNAm) age of these samples using the Horvath clock. The most pronounced increase in DNAm age could be observed in ERCC1 mice, a strain which exhibits a deficit in DNA nucleotide excision repair. In line with these results, we detected an increase in epigenetic age in fibroblasts isolated from patients with progeroid syndromes associated with mutations in DNA excision repair genes. These findings highlight ERCC1 as a particularly attractive mouse model to study aging in mammals and suggest a strong connection between DNA damage and epigenetic dysregulation during aging.

molecular biology↗

DNA methylation age studies of humpback whales

Several previous studies have described epigenetic clocks for whale and dolphin species. Here we present a novel and highly robust epigenetic clock for the humpback whale based on methylation levels measured using the Mammalian Methylation Array platform. Skin samples were obtained from 76 individuals that had been studied since their birth year and known to range in age from <1 to 39.5 years. The humpback whale clock provided a highly accurate estimate of chronological age (R=0.96, median error 2.2 years) according to a leave-one-out cross validation analysis. We applied this clock to an independent set of samples from humpback whales of unknown exact age but with sighting histories that were as long as or longer than the upper 20% of the available known-age range. Although there was a strong correlation with minimum age (R=0.89), the clock underestimated age in these older animals by a median error of at least 7.8 years. Finally, we applied the humpback clock to publicly available methylation data from beluga whales. In this data set from a different species, the humpback clock provided an age correlation of R=0.78. While a DNAm age estimator has previously been described for humpback whales, this is the first such clock shown to apply to another cetacean species as well. Our humpback whale clock built from well-studied population lends itself for understanding humpback populations that otherwise lack age data.

developmental biology↗