Biology subjects

Haynes, K. A.

Publications and source records attributed to Haynes, K. A..

13 recordsLinked to original sources

bioRxiv2026

Molecular mechanisms underlying amyloid lowering by aducanumab: differential and comparative effects of sex and IgG reveal the post-treatment disease brain

INTRODUCTIONImproving the predictive validity of preclinical studies for Alzheimers disease (AD) requires rigorous evaluation of therapeutic efficacy, safety, and sex-specific responses in translationally relevant models. As amyloid-targeting monoclonal antibodies continue to advance clinically, there is an urgent need to define the molecular milieu that persists after amyloid is reduced and disease progression continues. Leveraging the NIA-funded MODEL-AD Preclinical Testing Core, we investigated the biochemical, functional, and multi-omic signatures associated with chronic administration of murine chimeric aducanumab (chAdu) in 5XFAD mice, including the contribution of IgG-mediated effects. METHODSMale and female 5XFAD mice were treated weekly with chAdu beginning at 8 months of age and compared to age-and sex-matched murine IgG2a{kappa} isotype (IgG) and saline controls. Plasma and brain pharmacokinetics, amyloid-beta (A{beta}), behavioral assessments, and treatment-emergent anti-drug antibodies (ADAs) were quantified. Post-treatment transcriptomic and proteomic analyses were performed to assess molecular pathways associated with chAdu and IgG exposure following 17-week treatment. RESULTSchAdu produced sex-dependent changes in A{beta}, including increased plasma A{beta}42:40 and reductions in brain A{beta} which were associated with mild behavioral impairments in the absence of improvements in cognitive function. IgG control treatment produced similar reductions, indicating biologically active IgG-mediated processes independent of A{beta}-targeted specificity. Treatment-emergent ADAs occurred in 10% of chAdu-treated mice and were associated with reduced drug exposure and efficacy. Multi-omics analyses confirmed sex-dependent and IgG-mediated effects at both the transcriptomic and proteome level revealing disease-associated genes and proteins not altered despite reductions in amyloid with treatment. DISCUSSIONThese findings demonstrate sex-dependent PK and pharmacodynamic responses to chAdu, identify biologically meaningful IgG-driven effects, and reveal molecular signatures that persist after amyloid reduction. This work provides biological insights into pathways that may remain insufficiently addressed following amyloid lowering; revealing novel targets for future drug discovery to prevent and treat disease.

neuroscience↗

bioRxiv2026

Early Epigenetic and Metabolic Responses to the Adipocyte Secretome Reveal Stress-Adaptive States in Triple-Negative Breast Cancer

Obesity is a well-established risk factor for triple-negative breast cancer (TNBC), yet how adipocyte-derived signals reprogram cancer cell metabolism and chromatin states remains poorly defined. Here, we investigate how adipocyte-driven lipogenesis reshapes metabolic-epigenetic coupling to support stress-adaptive cell states and functional changes in epithelial TNBC cells. Using an integrated multi-omic approach, we combine RNA sequencing (RNA-seq), chromatin accessibility (ATAC-seq), metabolic flux modeling, and functional metabolic assays in lipogenic BT-549 cells. Computational modeling trained on RNA-seq predicts shifts in metabolic pathway usage, including enhanced NAD-linked metabolism. RNA-seq reveals a predominance of gene activation, consistent with ATAC-seq data showing a strong bias toward increased accessibility. Regions of increased accessibility are enriched for stress-adaptive and antioxidant pathways, including superoxide dismutase 2 (SOD2) and metallothioneins (MT1F, MT1E, MT2A). Functionally, lipogenic cells exhibit increased spare respiratory capacity, altered ATP-linked respiration, elevated extracellular acidification, and reduced reactive oxygen species (ROS) accumulation, consistent with a bioenergetically flexible, stress-adaptive metabolic state. Together, these findings reveal that adipocyte-driven metabolic rewiring promotes selective chromatin opening and activation of stress-adaptive gene programs, enabling TNBC cells to buffer oxidative pressure for enhanced proliferation and survival after exposure to the adipocyte secretome.

cancer biology↗

bioRxiv2025

Decoding Gene Responsiveness to Synthetic Chromatin Reader-Actuators with Multi-Modal Epigenomic Profiling

Cell identity is regulated by chromatin states that encode gene regulatory memory and shape responses to new inputs. To investigate how chromatin context influences inducibility in differentiated cells, we employed engineered synthetic reader-actuators (SRAs), fusion proteins containing the polycomb chromodomain (PCD) that binds H3K27me3. In MCF7 breast cancer cells, we mapped PCD-fusion occupancy by ChIP-seq and used RNA-seq to identify temporally resolved gene activation patterns. ChIP-seq profiling and machine learning models (MLM) demonstrated that PCD-fusion binding was predicted by the presence of H3K27me3, H4K20me1, or H3K36me3 enrichment, suggesting selective accessibility at enhancers and chromatin transition zones. Among genes with PCD-fusion enriched enhancers, the SRA-induced subset was distinguished by promoter features including bivalent histone modifications and enrichment of transcriptional repressors REST and MTA1. Collectively, our results demonstrate that SRA responsiveness depends on a specific chromatin signature beyond H3K27me3 alone. This study demonstrates the power of SRAs to dissect inducible chromatin features in their native genomic context, and suggests that epigenetically repressed regions in differentiated cells can retain regulatory plasticity.

synthetic biology↗

bioRxiv2024

Tet Transgene Activation is Disrupted in Lipogenic Triple Negative Breast Cancer Cells

An important challenge for mammalian cell engineering is the unexpected response of transgenes to native transcriptional regulation pathways. One transgene can show different levels of expression at different genomic sites, in different cell types, and under different growth conditions. Collisions between transcription and DNA replication, heterochromatin encroachment, and viral defense have been linked to transgene silencing. In this study we identify fatty acid metabolism as another mediator of transgene behavior. Adipocyte secretome-induced lipogenesis in epithelial breast cancer cells was accompanied by the loss of expression from a Tet-TA regulated pCMV-AmCyan fluorescent protein (CFP) transgene. Transcription profiling verified the activation of lipid droplet biosynthesis genes, and revealed repression of loci at every chromosome, consistent with the idea that lipogenesis affects the availability of substrates and cofactors for global chromatin remodeling. Pre-induction of pCMV prevented full transgene silencing during lipogenesis. Our results provide new insights into the influence of the lipogenic epigenetic state on transgene behavior.

synthetic biology↗

bioRxiv2024

An engineered chromatin protein with enhanced preferential binding of H3K27me3 over H3K9me3

Histone post-translational modifications (PTMs) in chromatin modulate enhancer function, gene expression, and cellular differentiation. Pockets within chromatin reader-effector proteins bind specific histone PTMs, and have informed the design of artificial probes. Histone binding domains (HBDs) interact via multiple contacts that may support greater specificity than antibodies, but are difficult to study because of their weak affinities in vitro. We used a "Cell-Free Histone-Binding Immunoassay" (CHIA) where interactions between cell-free-expressed engineered HBD proteins and immobilized histone peptides are measured in an ELISA system. Previously reported K33E and Q9D variants of the chromobox 7 (CBX7) HBD bound with high affinity to both H3K27me3 and H3K9me3. However in CBX8, the K33E substitution enhanced binding to K27me3 with minimal K9me3 binding. Furthermore, hydrophobic substitutions in the CBX8 hydrophobic clasp (V10, L49) supported affinity and specificity for K27me3. We demonstrate the utility of a new CBX8 variant as a H3K27me3-specific live cell chromatin probe.

synthetic biology↗

bioRxiv2024

The T-cell niche tunes immune function through modulation of the cytoskeleton and TCR-antigen forces

Obesity is a major public health crisis given its rampant growth and association with an increased risk for cancer. Interestingly, patients with obesity tend to have an increased tumor burden and decreased T-cell function. It remains unclear how obesity compromises T-cell mediated immunity. To address this question, we modeled the adipocyte niche using the secretome released from adipocytes as well as the niche of stromal cells and investigated how these factors modulated T-cell function. We found that the secretomes altered antigen-specific T-cell receptor (TCR) triggering and activation. RNA-sequencing analysis identified thousands of gene targets modulated by the secretome including those associated with cytoskeletal regulation and actin polymerization. We next used molecular force probes to show that T-cells exposed to the adipocyte niche display dampened force transmission to the TCR-antigen complex and conversely, stromal cell secreted factors lead to significantly enhanced TCR forces. These results were then validated in diet-induced obese mice. Importantly, secretome-mediated TCR force modulation mirrored the changes in T-cell functional responses in human T-cells using the FDA-approved immunotherapy, blinatumomab. Thus, this work shows that the adipocyte niche contributes to T-cell dysfunction through cytoskeletal modulation and reduces TCR triggering by dampening TCR forces consistent with the mechanosensor model of T-cell activation.

bioengineering↗

bioRxiv2023

Characterizing Molecular and Synaptic Signatures in Mouse Models of Late-Onset Alzheimer's Disease Independent of Amyloid and Tau Pathology

Structured AbstractO_ST_ABSINTRODUCTIONC_ST_ABSMODEL-AD is creating and distributing novel mouse models with humanized, clinically relevant genetic risk factors to more accurately mimic LOAD than commonly used transgenic models. METHODSWe created the LOAD2 model by combining APOE4, Trem2*R47H, and humanized amyloid-beta. Mice aged up to 24 months were subjected to either a control diet or a high-fat/high-sugar diet (LOAD2+HFD) from two months of age. We assessed disease-relevant outcomes, including in vivo imaging, biomarkers, multi-omics, neuropathology, and behavior. RESULTSBy 18 months, LOAD2+HFD mice exhibited cortical neuron loss, elevated insoluble brain A{beta}42, increased plasma NfL, and altered gene/protein expression related to lipid metabolism and synaptic function. In vivo imaging showed age-dependent reductions in brain region volume and neurovascular uncoupling. LOAD2+HFD mice also displayed deficits in acquiring touchscreen-based cognitive tasks. DISCUSSIONCollectively the comprehensive characterization of LOAD2+HFD mice reveal this model as important for preclinical studies that target features of LOAD independent of amyloid and tau.

neuroscience↗

bioRxiv2023

PIC recruitment by synthetic reader-actuators to polycomb-silenced genes blocks triple-negative breast cancer invasion

Scientists have used small molecule inhibitors and genetic knockdown of gene-silencing polycomb repressive complexes (PRC1/2) to determine if restoring the expression of tumor suppressor genes can block proliferation and invasion of cancer cells. A major limitation of this approach is that inhibitors can not restore key transcriptional activators that are mutated in many cancers, such as p53 and members of the BRAF SWI/SNF complex. Furthermore, small molecule inhibitors can alter the activity of, rather than inhibit, the polycomb enzyme EZH2. While chromatin has been shown to play a major role in gene regulation in cancer, poor clinical results for polycomb chromatin-targeting therapies for diseases like triple-negative breast cancer (TNBC) could discourage further development of this emerging avenue for treatment. To overcome the limitations of inhibiting polycomb to study epigenetic regulation, we developed an engineered chromatin protein to manipulate transcription. The synthetic reader-actuator (SRA) is a fusion protein that directly binds a target chromatin modification and regulates gene expression. Here, we report the activity of an SRA built from polycomb chromodomain and VP64 modules that bind H3K27me3 and subunits of the Mediator complex, respectively. In SRA-expressing BT-549 cells, we identified 122 upregulated differentially expressed genes (UpDEGs, [≥] 2-fold activation, adjusted p < 0.05). On-target epigenetic regulation was determined by identifying UpDEGs at H3K27me3-enriched, closed chromatin. SRA activity induced activation of genes involved in cell death, cell cycle arrest, and the inhibition of migration and invasion. SRA-expressing BT-549 cells showed reduced spheroid size in Matrigel over time, loss of invasion, and activation of apoptosis. These results show that Mediator-recruiting regulators broadly targeted to silenced chromatin activate silenced tumor suppressor genes and stimulate anti-cancer phenotypes. Therefore further development of gene-activating epigenetic therapies might benefit TNBC patients.

synthetic biology↗

bioRxiv2021

Targeted regulation of plasmid DNA expression in eukaryotic cells with a methylated-DNA-binding activator

PurposeTargeted regulation of transfected extra-chromosomal plasmid DNA typically requires the integration of 9 - 20 bp docking sites into the plasmid. Here, we report an elegant approach, The Dpn Adaptor Linked Effector (DAL-E) system, to target fusion proteins to 6-methyladenosine in GATC, which appears frequently in popular eukaryotic expression vectors and is absent from endogenous genomic DNA. Methods: The DNA-binding region from the DpnI endonuclease binds 6-methyladenosine within the GATC motif. We used a Dpn-transcriptional activator (DPN7-TA) fusion to induce gene expression from transiently transfected pDNAs. ResultsWe validated methylation-dependent activity of DPN7-TA with a panel of target pDNAs. We observed stronger transactivation when GATC targets were located upstream of the transcriptional start site in the target pDNA. Conclusion: DAL-E, consisting of a 108 aa, 12 kD DNA-binding adaptor and a 4 bp recognition site, offers a genetically-tractable, tunable system that can potentially be redesigned to recruit a variety of regulators (e.g. activators, silencers, epigenome editors) to transfected plasmid DNA. LAY SUMMARYTransfection of plasmid DNA (pDNA) is a commonly used method for introducing exogenous genetic material into mammalian cells. Once introduced into cells not all pDNAs express this genetic material at sufficient levels. Current techniques to improve transgene expression are limited and are not always feasible for all plasmids. This report presents a new method to improve gene expression from pDNA. The Dpn Adaptor Linked Effector (DAL-E) binds to methylated adenines in the pDNA resulting in increased expression. This technique has exciting implications for improved genetic engineering of mammalian cells. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=124 HEIGHT=200 SRC="FIGDIR/small/466616v1_ufig1.gif" ALT="Figure 1"> View larger version (44K): org.highwire.dtl.DTLVardef@1116db0org.highwire.dtl.DTLVardef@1386f99org.highwire.dtl.DTLVardef@26c63corg.highwire.dtl.DTLVardef@1a09673_HPS_FORMAT_FIGEXP M_FIG C_FIG

synthetic biology↗

bioRxiv2020

Delivery of cell-penetrating chromatin sensor-actuators to human osteosarcoma cells

The leading FDA-approved drugs for epigenetic cancer therapy are small molecule compounds that activate silenced tumor suppressors by inhibiting enzymes that generate aberrant repressive chromatin. Although promising, this approach is limited because chromatin-modifying enzymes often target non-chromatin proteins and can serve dual functions as gene repressors and activators. Previously, we have demonstrated that a transgenically expressed synthetic polycomb-derived transcription factor (PcTF) could activate genes in silenced chromatin via specific interactions with histone H3 trimethylated at lysine 27 (H3K27me3). Efficient non-viral intracellular delivery remains a challenge for protein-based biologics. Herein, we report the delivery of cell-penetrating PcTF (CP-PcTF) to cultured cells. We expressed and purified recombinant PcTF that was fused in frame with a nuclear localization signal and a cell penetrating peptide tag (TAT). We demonstrated rapid and efficient uptake of soluble CP-PcTF by osteosarcoma U-2 OS cells grown in 2-D monolayers and 3-D spheroids. However, CP-PcTF had a modest effect on gene expression and cell proliferation compared to transgenically-expressed PcTF from our previous work. Overall, these results suggest that TAT is a very effective delivery vehicle for the recombinant transcriptional regulator PcTF, and that further technical development is needed to deliver functional PcTF into cell nuclei.

synthetic biology↗

bioRxiv2018

Use of MYB as a new synthetic activator to enhance transgene expression within repressed Polycomb chromatin

Epigenetic silencing of transgenes has been a persistent challenge for mammalian cell engineering. Foreign DNA can be incorporated into closed chromatin before and after it has been integrated into a host cells genome. To identify elements that mitigate epigenetic silencing, we tested components from the c-myb and NF-kB transcriptional regulation systems in transiently transfected DNA and at chromosomally integrated transgenes in PC-3 and HEK293 cells. DNA binding sites for MYB (c-myb) placed upstream of a minimal promoter strongly enhanced expression from transiently transfected plasmid DNA. We targeted p65 and MYB fusion proteins to chromosomal transgenes that were silenced by ectopic Polycomb chromatin or by uncharacterized endogenous chromatin. Transient expression of Gal4-MYB induced sustained activation of the Polycomb-silenced UAS-Tk-luciferase transgene. We used custom guide RNAs and dCas9-MYB to target MYB to different sites. Transgene activation within ectopic Polycomb chromatin required proximity of dCas9-MYB to the transcriptional start site, while activation at the naturally repressed transgene was position-independent. Our report is the first to demonstrate the use of MYB in the context of the CRISPR-activation system. The results demonstrate that DNA elements and fusion proteins derived from c-myb can mitigate epigenetic silencing to improve transgene expression in engineered cell lines.

synthetic biology↗

bioRxiv2018

Characterization of Diverse Homoserine Lactone Synthases in Escherichia coli

Quorum sensing networks have been identified in over one hundred bacterial species to date. A subset of these networks regulate group behaviors, such as bioluminescence, virulence, and biofilm formation, by sending and receiving small molecules called homoserine lactones (HSLs). Bioengineers have incorporated quorum sensing pathways into genetic circuits to connect logical operations. However, the development of higher-order genetic circuitry is inhibited by crosstalk, in which one quorum sensing network responds to HSLs produced by a different network. Here, we report the construction and characterization of a library of ten synthases including some that are expected to produce HSLs that are incompatible with the Lux pathway, and therefore show no crosstalk. We demonstrated their function in a common lab chassis, Escherichia coli BL21, and in two contexts, liquid and solid agar cultures, using decoupled Sender and Receiver pathways. We observed weak or strong stimulation of a Lux Receiver by longer-chain or shorter-chain HSL-generating Senders, respectively. We also considered the under-investigated risk of unintentional release of incompletely deactivated HSLs in biological waste. We found that HSL-enriched media treated with bleach is still bioactive, while autoclaving deactivates LuxR induction. This work represents the most extensive comparison of quorum sensing synthases to date and greatly expands the bacterial signaling toolkit while recommending practices for disposal based on empirical, quantitative evidence.

synthetic biology↗

bioRxiv2017

Tandem histone-binding domains enhance the activity of a synthetic chromatin effector

Fusion proteins that specifically interact with biochemical marks on chromosomes represent a new class of synthetic transcriptional regulators that decode cell state information rather than DNA sequences. In multicellular organisms, information relevant to cell state, tissue identity, and oncogenesis is often encoded as biochemical modifications of histones, which are bound to DNA in eukaryotic nuclei and regulate gene expression states. We have previously reported the development and validation of the \"Polycomb-based transcription factor\" (PcTF), a fusion protein that recognizes histone modifications through a protein-protein interaction between its polycomb chromodomain (PCD) motif and trimethylated lysine 27 of histone H3 (H3K27me3) at genomic sites. We demonstrated that PcTF activates genes at methyl-histone-enriched loci in cancer-derived cell lines. However, PcTF induces modest activation of a methyl-histone associated reporter compared to a DNA-binding activator. Therefore, we modified PcTF to enhance its target affinity. Here, we demonstrate the activity of a modified regulator called Pc2TF, which has two tandem copies of the H3K27me3-binding PCD at the N-terminus. Pc2TF shows higher affinity for H3K27me3 in vitro and shows enhanced gene activation in HEK293 cells compared to PcTF. These results provide compelling evidence that the intrinsic histone-binding activity of the PCD motif can be used to tune the activity of synthetic histone-binding transcriptional regulators.

synthetic biology↗