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Biology subjects

Rehman, J.

Publications and source records attributed to Rehman, J..

At least 19 recordsLinked to original sources

Compact adenine base editors to enable therapeutic rescue of Duchenne muscular dystrophy

Adenine base editors (ABEs) have emerged as a powerful gene-editing technology enabling precise and programmable adenine-to-guanine substitutions across the genome. However, their translation into in vivo therapeutics is limited by delivery challenges, as their size exceeds the packaging capacity of adeno-associated virus (AAV). Here, we report the discovery, structural characterization, and engineering of two compact, highly active ABEs built on novel deaminases and Cas9d nucleases, enabling all-in-one, single-vector AAV delivery. Applying these compact ABEs to Duchenne muscular dystrophy (DMD), we demonstrate efficient disruption of conserved splice-acceptor sites at dystrophin exons 45 and 51 in human skeletal muscle cells, enabling therapeutically relevant exon skipping. Together, these ABEs help expand the therapeutic reach of base editing towards diverse tissue types and disease targets.

bioengineering↗

Regulatory network architecture constrains inflammatory responses in tissue-resident alveolar macrophages

Macrophages across different tissues exhibit remarkable functional diversity while maintaining core innate immune-cell programming. These complex programs are governed by gene regulatory networks, in which precise transcription factor activity tunes the expression of functionally relevant gene modules. Although the contributions of individual transcription factors have been well characterized, the higher-order regulatory interactions that coordinate tissue-resident macrophage identity and inflammatory response regulation remain poorly understood. Here, we integrate single-cell RNA-seq data with ATAC-seq profiling and deep-learning-based chromatin accessibility modeling to infer gene regulatory network architectures in tissue-resident versus recruited monocyte-derived alveolar macrophages under inflammatory stress. Our results suggest that inflammatory responses are more restrained in tissue-resident alveolar macrophages compared with recruited macrophages due to a stabilizing regulatory network architecture involving PU.1 and CEBP/{beta}. This work advances our understanding of functional plasticity in tissue-resident macrophages and their role in host defense.

immunology↗

Ionic Regulation of Mechanosurveillance and Metastasis via the MRTFA/KCNMB1 Axis

Cellular stiffness profoundly impacts cancer metastasis at multiple levels, but mechanisms that regulate cancer cells stiffness remain poorly understood. Here, we identified potassium efflux and KCNMB1, an auxiliary subunit of the large conductance potassium efflux (BK) channels, as regulators of cellular stiffness downstream of myocardin related transcription factor A (MRTFA). In primary pericytes, KCNMB1 knockdown increased cellular stiffness, which is consistent with the role of potassium efflux in promoting relaxation during excitation-contraction coupling. In a striking contrast, however, KCNMB1 knockdown decreased cellular stiffness in cancer cells. Softer cancer cells were resistant to NK cell mediated cytotoxicity and the low KCNMB1 expression was associated with worse survival in breast cancer patients. Importantly, pharmacological activation of BK channels reduced metastatic burden in mice and improved lysis of cancer cells by cytotoxic T-lymphocytes. These results highlight the unique ionic regulation of stiffness in cancer cells and point to BK channel agonism as a new therapeutic approach in cancer.

cancer biology↗

NicheProt: Cell-type-resolved proteomics of tissue compartments

Spatial proteomics uncovers the molecular underpinnings of cellular function in intact tissues. Laser capture microdissection coupled with mass spectrometry enables comprehensive proteomic profiling of selected tissue regions, but typically does not support cell-type-specific proteomic analysis. We present NicheProt, a 3D optical microscopy-guided, photobleaching-mediated cell barcoding approach for isolating intact specific cell types from defined microanatomical tissue compartments or niches. Using sequential bottom-up proteomic analysis, we defined two distinct phenotypes of CD11c dendritic cells based on their spatial locations in the inflamed mouse spleen. These two compartment-specific dendritic cell populations were characterized by proteomic signatures differing in the levels of 54 proteins. This 3D tissue microscopy-guided method offers cell-type and microregion-resolved proteomic analysis, facilitating the proteomic discovery of previously unrecognized cell subtypes and their functional roles in distinct tissue compartments.

systems biology↗

Integrative analysis of spatiotemporal transcriptomics delineates dynamic cell states in squamous tumorigenesis

Squamous cell cancers are responsible for 1 in 5 cancer deaths and survival improvements lag behind those seen in adenocarcinomas. This disparity is in large part due to the limited impact of immunotherapy due to therapeutic resistance, where less than ten percent of patients respond in early stage squamous cell carcinomas of the Head and Neck. Mechanisms that govern intrinsic resistance remain poorly understood and likely arise during the premalignant or dysplastic state. Here, we generated a dataset of murine and human oral squamous epithelia spanning the earliest premalignant stages through invasive carcinoma. Integrative analysis of single-cell and spatial transcriptomics data across the dysplasia to carcinoma continuum reveals early and sustained shifts in epithelial transcriptomes. Spatially informed cell-cell interaction analysis reveals dysplasia-specific upregulation of wound healing and immune remodeling programs in severe dysplasia and invasive carcinoma in a human sample of oral dysplasia. The presence of these transcriptomic programs within early dysplasia may account for the aggressive clinical presentations of squamous cancers including intrinsic therapeutic resistance.

cancer biology↗

Persistent Immune Dysregulation during Post-Acute Sequelae of COVID-19 is Manifested in Antibodies Targeting Envelope and Nucleocapsid Proteins

Post-Acute Sequelae of SARS-CoV-2 infection (PASC) syndrome or "Long COVID" represents a widespread health challenge that necessitates the development of novel diagnostic approaches and targeted therapies that can be readily deployed. Immune dysregulation has been reported as one of the hallmarks of PASC, but the extent of PASC immune dysregulation in patients over time remains unclear. We therefore assessed SARS-CoV-2-specific antibody responses, peripheral immune cell profiles, autoantibody profiles and circulating cytokines for up to 6 months in participants with a SARS-CoV-2 infection who either convalesced or developed PASC. Compared to convalescent, PASC participants with a broad range of PASC phenotypes exhibited persistently elevated IgG titers for SARS-CoV-2 Envelope and Nucleocapsid proteins over the 6 months of study duration. In contrast, the IgG responses to Spike protein were significantly lower in the PASC cohort with predominantly IgG1 and IgG3 class-switched bias. Using CyTOF analysis, we show elevated numbers of circulating T follicular helper cells (cTFH) and mucosa-associated invariant T cells (MAIT), which also correlated with high anti-Envelope IgG titers. Persistent immune activation was accompanied by augmented serum cytokine profiles with LIF, IL-11, Eotaxin-3, and HMGB-1 in PASC participants, who also demonstrated significantly higher rates of autoantibodies. These findings highlight the persistence of immune dysregulation in PASC, underscoring the need to explore targeted therapies addressing viral persistence, dysregulated antibody production, and autoimmunity.

immunology↗

Local optogenetic control of genome editing and tumorigenesis in vivo using wireless implantable optoelectronics

Precise spatial regulation of site-specific DNA recombination (SSR) in vivo remains a challenge due to limited tunability of current platforms. Here, we present an optogenetic approach that overcome these limitations by employing engineered light-regulated recombinase E-LightR-Cre and tunable wireless implantable optoelectronic devices. E-LightR-Cre meets the key criteria for spatial regulation of SSR in vivo, showing no detectable activity in the dark, while demonstrating robust activation upon blue-light illumination. To achieve local E-LightR-Cre activation in murine lungs, we developed wireless, fully-implantable optoelectronic devices enabling focal illumination with no discernible organ damage. By modulating illumination intensity and duration, we can control the size of the activated area. Local expression of oncogenic KRas-G12D in a photoactivated subpopulation of cells in vitro revealed rapid reprogramming of the mutant expressing cells and their non-activated neighbors. Light-guided activation of E-LightR-Cre in mouse lungs resulted in focal expression of a reporter gene and allowed us to induce local formation of oncogenic lesions in vivo.

bioengineering↗

scRegulate: Single-Cell Regulatory-Embedded Variational Inference of Transcription Factor Activity from Gene Expression

MotivationAccurately inferring transcription factor (TF) activity from single-cell RNA sequencing (scRNA-seq) data remains a fundamental challenge in computational biology. While existing methods rely on statistical models, motif enrichment, or prior-based inference, they often depend on deterministic assumptions about regulatory relationships and rely on static regulatory databases. Few approaches effectively integrate prior biological knowledge with data-driven inference to capture novel, dynamic, and context-specific regulatory interactions. ResultsTo address these limitations, we develop scRegulate, a generative deep learning framework leveraging variational inference to estimate TF activities guided by experimental TF-target gene relationships and progressively adapted based on the input scRNA-seq data. By integrating structured biological constraints with a probabilistic latent space model, scRegulate offers a scalable and biologically grounded estimation of TF activity and gene regulatory network (GRN). Comprehensively bench-marking on public experimental and synthetic datasets demonstrates scRegulates superior ability. Further, scRegulate accurately recapitulates experimentally validated TF knockdown effects on a Perturb-seq dataset for key TFs. Applied to experimental human PBMC scRNA-seq data, scRegulate infers cell-type-specific GRNs and identifies differentially active TFs aligned with known regulatory pathways. scRegulates TF activity representations capture transcriptional heterogeneity, enabling accurate clustering of cell types. scRegulate is highly efficient, frequently an order of magnitude faster than common baselines. Collectively, our results establish scRegulate as a powerful, interpretable, and scalable framework for inferring TF activities and GRNs from single-cell transcriptomics. AvailabilityResults and scripts available at github.com/YDaiLab/scRegulate. Supplementary informationSupplementary data are available at Bioinformatics online.

bioinformatics↗

Inhibition of β-catenin signaling by Amyloid-β in endothelial cells impairs vascular barrier integrity

Dysfunction of the blood-brain barrier (BBB) is emerging as a critical mediator of Alzheimers Disease (AD) progression and precedes the formation of large Amyloid-{beta} (A{beta}) plaques in AD patients. Maintenance of the blood brain barrier integrity by brain microvascular endothelial cells (BMECs) is essential for brain homeostasis and is in part maintained by WNT/{beta}-catenin signaling. We hypothesized that A{beta} induces blood-brain barrier dysfunction by inhibiting WNT/{beta}- catenin signaling in brain endothelial cells, leading to reduced expression of BBB-related genes and barrier function. In brain endothelial cells, we found that A{beta} directly decreased {beta}-catenin transcriptional activity, but also inhibited activation of {beta}-catenin by the WNT3A peptide. Additionally, A{beta} reduced barrier integrity of ECs, which was in part restored by exposure to exogenous WNT3A. We observed A{beta}-induced inhibition within 3 hours of exposure. A{beta}-induced inhibition of {beta}-catenin signaling was consistent across both immortalized brain ECs and ECs differentiated from human induced pluripotent stem cells(iPSCs). We next investigated human iPSCs with and without the N141I mutation in presenilin-2 (PSEN2), known to increase A{beta} buildup and familial AD risk. We found the AD ECs showed smaller cell size and expressed lower VE-cadherin at the protein level. RNA sequencing revealed that the presence of PSEN2 N141I did not significantly impact gene expression of genes coding for proteins canonically involved in barrier integrity but did show differences in the expression of transposable elements. These results indicate that BBB dysfunction early in AD may be the result of A{beta} in the brain impairing WNT/{beta}-catenin signaling which maintains the barrier integrity of brain endothelial cells.

neuroscience↗

Matrimeres are systemic nanoscale mediators of tissue integrity and function

Tissue barriers must be rapidly restored after injury to promote regeneration. However, the mechanism behind this process is unclear, particularly in cases where the underlying extracellular matrix is still compromised. Here, we report the discovery of matrimeres as constitutive nanoscale mediators of tissue integrity and function. We define matrimeres as non-vesicular nanoparticles secreted by cells, distinguished by a primary composition comprising at least one matrix protein and DNA molecules serving as scaffolds. Mesenchymal stromal cells assemble matrimeres from fibronectin and DNA within acidic intracellular compartments. Drawing inspiration from this biological process, we have achieved the successful reconstitution of matrimeres without cells. This was accomplished by using purified matrix proteins, including fibronectin and vitronectin, and DNA molecules under optimal acidic pH conditions, guided by the heparin-binding domain and phosphate backbone, respectively. Plasma fibronectin matrimeres circulate in the blood at homeostasis but exhibit a 10-fold decrease during systemic inflammatory injury in vivo. Exogenous matrimeres rapidly restore vascular integrity by actively reannealing endothelial cells post-injury and remain persistent in the host tissue matrix. The scalable production of matrimeres holds promise as a biologically inspired platform for regenerative nanomedicine.

bioengineering↗

SenePy: Unveiling the Cell-Type Specific Landscape of Cellular Senescence through Single-Cell Analysis in Living Organisms

Senescent cells accumulate in tissues with organismal age and contribute causally to multiple chronic diseases. In vivo senescent cell phenotypes are heterogeneous because cellular context and stressors vary by cell type and tissue. Due to the variability of senescence programs, there is no universal method to identify senescent cells and even widely used markers, such as CDKN2A, are not ubiquitous. Therefore, we interrogated the Tabula Muris Senis mouse single-cell aging atlas and an array of single-cell datasets from human donors that spanned many ages to find cell-specific signatures of cellular senescence. We derived 75 mouse and 65 human senescence signatures from individual cell populations. CDKN2A and other markers of senescence were overrepresented in these signatures but there were many novel senescence genes present at higher rates. Within individual cell populations, we observed multiple programs of senescence with distinct temporal and transcriptional characteristics. We packaged the signatures along with a single-cell scoring method into an open-source package: SenePy. SenePy signatures better recapitulate cellular senescence than available methods when tested on multiple in vivo RNA-seq datasets and a p16ink4a reporter single-cell dataset. We used SenePy to map the kinetics of senescent cell accumulation across 97 cell types from humans and mice. SenePy also generalizes to disease-associate senescence and we used it to identify an increased burden of senescent cells in COVID-19 and myocardial infarction. This work provides a significant advancement towards our ability to identify and characterize in vivo cellular senescence.

cell biology↗

Limited Diffusion of Scientific Knowledge Forecasts Collapse

Market bubbles emerge when asset prices are driven unsustainably higher than asset values and shifts in belief burst them. We demonstrate the same phenomenon for biomedical knowledge when promising research receives inflated attention. We predict deflationary events by developing a diffusion index that captures whether research areas have been amplified within social and scientific bubbles or have diffused and become evaluated more broadly. We illustrate our diffusion approach contrasting the trajectories of cardiac stem cell research and cancer immunotherapy. We then trace the diffusion of unique 28,504 subfields in biomedicine comprising nearly 1.9M papers and more than 80M citations and demonstrate that limited diffusion of biomedical knowledge anticipates abrupt decreases in popularity. Our analysis emphasizes that restricted diffusion, implying a socio-epistemic bubble, leads to dramatic collapses in relevance and attention accorded to scientific knowledge.

scientific communication and education↗

Impaired Barrier Integrity of the Skeletal Muscle Vascular Endothelium Drives Progression of Cancer Cachexia

Cancer patients experience cachexia, which is characterized by extensive skeletal muscle wasting that worsens the quality of life and increases mortality. Currently, there are no approved treatments that can effectively counteract cancer cachexia. Vascular endothelial cells (ECs) are essential for maintaining tissue perfusion, nutrient supply, and preventing inappropriate transmigration of immune cells into the tissue. However, little is known about the role of the muscle vasculature in cancer cachexia. We hypothesized that endothelial dysfunction in the skeletal muscle mediates cancer cachexia. Using transgenic pancreatic ductal adenocarcinoma (PDAC) mice and a tissue clearing and high-resolution 3D-tissue imaging approach, we found that the loss of skeletal muscle vascular density precedes the loss of muscle mass. Importantly, we show that cancer cachexia patients exhibit significantly decreased muscle vascular density and severe muscle atrophy when compared to non-cancer patients. Unbiased single cell transcriptomic analyses of the muscle endothelium unveiled a unique EC population present in cachexia muscles. Increased circulating Activin-A suppresses the expression of the transcriptional co-activator PGC1 in the muscle endothelium, thus disrupting junctional integrity in the vasculature and increasing vascular leakage. Conversely, restoration of endothelial-specific PGC1 prevented the decreased vascular density and muscle loss observed in tumor-bearing mice. Our study suggests that EC-PGC1 is essential for maintaining the integrity of the skeletal muscle vascular barrier and that restoring muscle endothelial function could be a valuable therapeutic approach to prevent or reverse cancer cachexia.

cancer biology↗

Parallel Activation of Src and Hif1α Increases Localized Glycolytic ATP Generation for Re-assembly of Endothelial Adherens Junctions

Endothelial adherens junctions (AJs) are critical for the regulation of vascular barrier integrity and undergo dis-assembly during inflammatory injury, thus causing vascular leakiness. AJ re-assembly is thus necessary for restoration of the endothelial barrier following the initial injury. Here we examine the metabolic underpinnings that drive restoration of vascular integrity. In response to inflammatory stimuli, the glycolysis regulatory enzyme PFKFB3 is activated, resulting in a rapid and sustained increase of intracellular glycolytic ATP, especially in the proximity of AJs at the plasma membrane. We engineered a novel chemo-genetic construct (RapT) which allowed for precise temporal control of PFKFB3 recruitment to the plasma membrane. Activation of RapT by rapamycin during the barrier restoration phase increased regional ATP and accelerated AJ re-assembly. Mechanistically, we observed that PFKFB3 is activated through two modes. Src-mediated post-translational phosphorylation rapidly increases PFKFB3 activity. Using another chemo-genetic approach to temporally control Src activity, we found that Src activates PFKFB3 by binding to and phosphorylating it at residues Y175, Y334, and Y363. Tyrosine-phospho-deficient mutants of PFKFB3 at these residues block the glycolytic activation upon inflammatory stimuli. In parallel, elevated reactive oxygen species generated during inflammatory stimulation create pockets of regional hypoxia and allow for increased Hif1-mediated transcription of PFKFB3, leading to sustained glycolytic activation. Moreover, inhibition of PFKFB3 delays AJ reassembly and restoration of vascular integrity both in vitro and in vivo. In conclusion, we show that while inflammatory activation acutely compromises the endothelial barrier, inflammatory signaling also concomitantly generates a metabolic milieu in anticipation of the subsequent re-assembly of AJs and restoration of the vascular barrier.

cell biology↗

Two-color live-cell STED nanoscopy by click labeling with cell-permeable fluorophores

STED nanoscopy allows for the direct observation of dynamic processes in living cells and tissues with diffraction-unlimited resolution. Although fluorescent proteins can be used for STED imaging, these labels are often outperformed in photostability by organic fluorescent dyes. This feature is especially crucial for time-lapse imaging. Unlike fluorescent proteins, organic fluorophores cannot be genetically fused to a target protein but require different labeling strategies. To achieve simultaneous imaging of more than one protein in the interior of the cell with organic fluorophores, bioorthogonal labeling techniques and cell-permeable dyes are required. In addition, the fluorophores should preferentially emit in the red spectral range to reduce potential phototoxic effects that can be induced by the STED light, which further restricts the choice of suitable markers. Here we demonstrate two-color STED imaging of living cells using various pairs of dyes that fulfill all of the above requirements. To this end, we combine click-chemistry-based protein labeling with other orthogonal and highly specific labeling methods, enabling long-term STED imaging of different target structures in living specimens.

biophysics↗

Pink1-mediated mitophagy in the endothelium releases proteins encoded by mitochondrial DNA and activates neutrophil responses

Given their ancient evolutionary origins, eukaryotic mitochondria possess multiple vestiges of their prokaryotic ancestors. One such factor is the N-terminal formylation of proteins encoded by mitochondrial DNA. N-formylated proteins are also released by bacteria and trigger activation of immune cells such as neutrophils. Growing evidence indicate that circulating levels of mitochondrial formyl proteins are elevated in the serum of patients with excessive inflammatory responses and trigger neutrophil activation like their bacterial counterparts. However, the cellular source of these proteins, and the mechanism by which they are released into the circulation is not known. In this study, we have identified vascular endothelial cells as a source of mitophagy induced release of formyl proteins in response to inflammatory mediators in vitro. Mechanistically, endothelial mitophagy required activation of the Pink1 pathway. Using liposomal delivery of sgRNA targeting Pink1 in mice expressing endothelial-specific Cas9, we developed a mouse model in which Pink1 is specifically depleted in the endothelium. Deletion of endothelial Pink1 was remarkably protective in endotoxin-induced lung inflammation, resulting in reduced neutrophil infiltration and significantly reduced death in mice. We thus propose that endothelial cells upregulate pro-inflammatory mitophagy in response to inflammation, leading to release of mitochondrial formyl peptides and detrimental neutrophil recruitment into the lung.

cell biology↗

An engineered ACE2 decoy receptor can be administered by inhalation and potently targets the BA.1 and BA.2 omicron variants of SARS-CoV-2

Monoclonal antibodies targeting the SARS-CoV-2 spike (S) glycoprotein neutralize infection and are efficacious for the treatment of mild-to-moderate COVID-19. However, SARS-CoV-2 variants have emerged that partially or fully escape monoclonal antibodies in clinical use. Notably, the BA.2 sublineage of B.1.1.529/omicron escapes nearly all monoclonal antibodies currently authorized for therapeutic treatment of COVID-19. Decoy receptors, which are based on soluble forms of the host entry receptor ACE2, are an alternative strategy that broadly bind and block S from SARS-CoV-2 variants and related betacoronaviruses. The high-affinity and catalytically active decoy sACE22.v2.4-IgG1 was previously shown to be effective in vivo against SARS-CoV-2 variants when administered intravenously. Here, the inhalation of sACE22.v2.4-IgG1 is found to increase survival and ameliorate lung injury in K18-hACE2 transgenic mice inoculated with a lethal dose of the virulent P.1/gamma virus. Loss of catalytic activity reduced the decoys therapeutic efficacy supporting dual mechanisms of action: direct blocking of viral S and turnover of ACE2 substrates associated with lung injury and inflammation. Binding of sACE22.v2.4-IgG1 remained tight to S of BA.1 omicron, despite BA.1 omicron having extensive mutations, and binding exceeded that of four monoclonal antibodies approved for clinical use. BA.1 pseudovirus and authentic virus were neutralized at picomolar concentrations. Finally, tight binding was maintained against S from the BA.2 omicron sublineage, which differs from S of BA.1 by 26 mutations. Overall, the therapeutic potential of sACE22.v2.4-IgG1 is further confirmed by inhalation route and broad neutralization potency persists against increasingly divergent SARS-CoV-2 variants.

microbiology↗

Engineered High-Affinity ACE2 Peptide Mitigates ARDS and Death Induced by Multiple SARS-CoV-2 Variants

Vaccine hesitancy and continuing emergence of SARS-CoV-2 variants of concern that may escape vaccine-induced immune responses highlight the urgent need for effective COVID-19 therapeutics. Monoclonal antibodies used in the clinic have varying efficacies against distinct SARS-CoV-2 variants; thus, there is considerable interest in engineered ACE2 peptides with augmented binding affinities for SARS-CoV-2 Spike protein. These could have therapeutic benefit against multiple viral variants. Using molecular dynamics simulations, we show how three amino acid substitutions in an engineered soluble ACE2 peptide (sACE22.v2.4-IgG1) markedly increase affinity for the SARS-CoV-2 Spike (S) protein. We demonstrate high binding affinity to S protein of the early SARS-CoV-2 WA-1/2020 isolate and also to multiple variants of concern: B.1.1.7 (Alpha), B.1.351 (Beta), P.1 (Gamma), and B.1.617.2 (Delta) SARS-CoV-2 variants. In humanized K18-hACE2 mice, prophylactic and therapeutic administration of sACE22.v2.4-IgG1 peptide prevented acute lung vascular endothelial injury and lung edema (essential features of ARDS) and significantly improved survival after infection by SARS-CoV-2 WA-1/2020 as well as P.1 variant of concern. These studies demonstrate for the first time broad efficacy in vivo of an ACE2 decoy peptide against multiple SARS-CoV-2 variants and point to its therapeutic potential.

pharmacology and toxicology↗