Biology subjects

Baker, A. H.

Publications and source records attributed to Baker, A. H..

7 recordsLinked to original sources

bioRxiv2025

Adiponectin exerts sex-dependent effects on lipid, amino acid, and glucose metabolism during caloric restriction

Adiponectin is the most abundant hormone in the circulation. Plasma adiponectin decreases in obesity but increases in leanness, including during caloric restriction (CR) in animals and humans. In obesity, adiponectin deficiency promotes cardiometabolic dysfunction. In contrast, the roles of adiponectin in CR, when it is at its highest, are largely unknown. To address this, we studied global adiponectin knockout (KO) in male and female mice fed either ad libitum (AL) or a 30% CR diet from 9-13 weeks of age. We show that adiponectin KO did not alter CR effects on body mass, body composition, or energy expenditure. However, KO unexpectedly decreased blood glucose levels during CR, both on fasting and following an oral glucose challenge. This is opposite to the effects of adiponectin deficiency in the context of ad libitum diet (AL) or obesity, and occurred without changes in insulin secretion or sensitivity. Moreover, adiponectin KO augmented CR-induced increases in plasma fatty acids in both sexes and, in males only, impaired systemic triglyceride clearance under CR. Indirect calorimetry further revealed that adiponectin KO alters the shifts between carbohydrate and lipid utilisation that occur during transitions between fed and fasted states. To determine potential molecular mechanisms, we investigated effects of adiponectin KO on the liver, a major adiponectin target that plays key roles entraining metabolism to nutritional state. Hepatic transcriptomics revealed that, in both sexes, adiponectin KO upregulates sterol and fatty acid synthesis genes under AL while increasing amino acid catabolic genes during CR. Together, our findings suggest that adiponectin tunes glucose, lipid, and amino acid metabolism during CR, in whole or in part through effects on the liver. The widely reported functions of adiponectin in pathological states, including obesity and insulin resistance, thus differ sharply from its roles during CR, with marked sexual dimorphism apparent for many of these functions.

physiology↗

bioRxiv2024

Functional screening identifies novel miRNAs inhibiting Vascular Smooth Muscle Cell proliferation

Proliferation of vascular smooth muscle cells (vSMCs) following injury is a crucial contributor to pathological vascular remodelling. MicroRNAs (miRNAs) are powerful gene regulators and attractive therapeutic agents. Here, we aim to systematically identify and characterise miRNAs with therapeutic potential in targeting aberrant vSMC proliferation. We performed a high-throughput in vitro screen using a library of 2042 human miRNA-mimics for their impact on vSMC proliferation and identified seven novel antiproliferative miRNAs i.e miR-323a-3p, miR449b-5p, miR-491-3p, miR-892b, miR-1827, miR-4774-3p, miR-5681b. Overexpression of these seven miRNAs affects proliferation of vSMCs from different vascular beds. Focusing on vein graft failure, a condition in which miRNA-based therapeutics can be applied to the graft ex-vivo, we showed that these miRNAs reduced human saphenous vein SMC (HSVSMC) proliferation without inducing apoptosis or senescence, and five of them also significantly decreased migration. HSVSMC transcriptomic analysis showed that each miRNA overexpression affects a core cell cycle gene network. However, this effect is mediated by distinct miRNA targets. In contrast to HSVSMC, miRNA overexpression in saphenous vein endothelial cells (ECs) led to no decrease or a less pronounced reduction in proliferation for the seven miRNAs. Transcriptomics analysis confirmed a distinct and limited response of ECs to the miRNA overexpression.

molecular biology↗

bioRxiv2023

INKILN is a novel long noncoding RNA promoting vascular smooth muscle inflammation

BackgroundActivation of vascular smooth muscle cells (VSMCs) inflammation is vital to initiate vascular disease. However, the role of human-specific long noncoding RNAs (lncRNAs) in VSMC inflammation is poorly understood. MethodsBulk RNA-seq in differentiated human VSMCs revealed a novel human-specific lncRNA called INflammatory MKL1 Interacting Long Noncoding RNA (INKILN). INKILN expression was assessed in multiple in vitro and ex vivo models of VSMC phenotypic modulation and human atherosclerosis and abdominal aortic aneurysm (AAA) samples. The transcriptional regulation of INKILN was determined through luciferase reporter system and chromatin immunoprecipitation assay. Both loss- and gain-of-function approaches and multiple RNA-protein and protein-protein interaction assays were utilized to uncover the role of INKILN in VSMC proinflammatory gene program and underlying mechanisms. Bacterial Artificial Chromosome (BAC) transgenic (Tg) mice were utilized to study INKLIN expression and function in ligation injury-induced neointimal formation. ResultsINKILN expression is downregulated in contractile VSMCs and induced by human atherosclerosis and abdominal aortic aneurysm. INKILN is transcriptionally activated by the p65 pathway, partially through a predicted NF-{kappa}B site within its proximal promoter. INKILN activates the proinflammatory gene expression in cultured human VSMCs and ex vivo cultured vessels. Mechanistically, INKILN physically interacts with and stabilizes MKL1, a key activator of VSMC inflammation through the p65/NF-{kappa}B pathway. INKILN depletion blocks ILI{beta}-induced nuclear localization of both p65 and MKL1. Knockdown of INKILN abolishes the physical interaction between p65 and MKL1, and the luciferase activity of an NF-{kappa}B reporter. Further, INKILN knockdown enhances MKL1 ubiquitination, likely through the reduced physical interaction with the deubiquitinating enzyme, USP10. INKILN is induced in injured carotid arteries and exacerbates ligation injury-induced neointimal formation in BAC Tg mice. ConclusionsThese findings elucidate an important pathway of VSMC inflammation involving an INKILN/MKL1/USP10 regulatory axis. Human BAC Tg mice offer a novel and physiologically relevant approach for investigating human-specific lncRNAs under vascular disease conditions.

molecular biology↗

bioRxiv2022

The endothelial-specific LINC00607 mediates endothelial angiogenic function

Long non-coding RNAs (lncRNAs) can act as regulatory RNAs which, by altering the expression of target genes, impact on the cellular phenotype and cardiovascular disease development. Endothelial lncRNAs and their vascular functions are largely undefined. Deep RNA-Seq and FANTOM5 CAGE analysis revealed the lncRNA LINC00607 to be highly enriched in human endothelial cells. LINC00607 was induced in response to hypoxia, arteriosclerosis regression in non-human primates and also in response to propranolol used to induce regression of human arteriovenous malformations. siRNA knockdown or CRISPR/Cas9 knockout of LINC00607 attenuated VEGF-A-induced angiogenic sprouting. LINC00607 knockout in endothelial cells also integrated less into newly formed vascular networks in an in vivo assay in SCID mice. Overexpression of LINC00607 in CRISPR knockout cells restored normal endothelial function. RNA- and ATAC-Seq after LINC00607 knockout revealed changes in the transcription of endothelial gene sets linked to the endothelial phenotype and in chromatin accessibility around ERG-binding sites. Mechanistically, LINC00607 interacted with the SWI/SNF chromatin remodeling protein BRG1. CRISPR/Cas9-mediated knockout of BRG1 in HUVEC followed by CUT&RUN revealed that BRG1 is required to secure a stable chromatin state, mainly on ERG-binding sites. In conclusion, LINC00607 is an endothelial-enriched lncRNA that maintains ERG target gene transcription by interacting with the chromatin remodeler BRG1.

molecular biology↗

bioRxiv2021

Human AdV-20-42-42, a promising novel adenoviral vector for gene therapy and vaccine product development

Pre-existing immune responses towards adenoviral vector limit the use of a vector based on particular serotypes and its clinical applicability for gene therapy and/or vaccination. Therefore, there is a significant interest to vectorize novel adenoviral types that have low seroprevalence in the human population. Here, we describe the discovery and vectorization of a chimeric human adenovirus, which we call HAdV-20-42-42. Full genome sequencing revealed that this virus is closely related to human serotype 42, except for the penton-base which is derived from serotype 20. The HAdV-20-42-42 vector could be propagated stably to high titers on existing E1-complementing packaging cell lines. Receptor binding studies revealed that the vector utilized both CAR and CD46 as receptors for cell entry. Furthermore, the HAdV-20-42-42 vector was potent in transducing human and murine cardiovascular cells and tissues, irrespective of the presence of blood coagulation factor X. In addition, the vector did not sequester in the liver upon intravenous administration in rodents. Finally, we demonstrate that potent T-cell responses against vector-delivered antigens could be induced upon vaccination. In summary, from the data obtained we conclude that HAdV-20-42-42 provides a valuable addition to the portfolio of adenoviral vectors available to develop safe and efficacious products in the fields of gene therapy and vaccination. IMPORTANCEAdenoviral vectors are currently under investigation for a broad range of therapeutic indications in diverse fields, such as oncology and gene therapy, as well as for vaccination both for human and veterinary use. A wealth of data shows that pre-existing immune responses may limit the use of a vector. Particularly in the current climate of global pandemic, there is a need to expand the toolbox with novel adenoviral vectors for vaccine development. Our data demonstrates that we have successfully vectorized a novel adenovirus serotype with low seroprevalence. The cell transduction data and antigen-specific immune responses induced in vivo demonstrate that this vector is highly promising for the development of gene therapy and vaccine products.

immunology↗

bioRxiv2020

A common analgesic enhances the anti-tumour activity of 5-aza-2'-deoxycytidine through induction of oxidative stress

The DNA demethylating agent 5-aza-2-deoxycytidine (DAC, decitabine) has anti-cancer therapeutic potential, but its clinical efficacy is hindered by DNA damage-related side effects. Here we describe how paracetamol augments the effects of DAC on cancer cell proliferation and differentiation, without enhancing DNA damage. Firstly, DAC specifically upregulates cyclooxygenase-2-prostaglandin E2 pathway, inadvertently increasing cancer cell survival, while the addition of paracetamol offsets this effect. Secondly, combined treatment leads to glutathione depletion and ROS accumulation with oxidative stress further enhanced by DAC suppressing anti-oxidant and thioredoxin responses. The benefits of combined treatment are demonstrated here in head and neck squamous cell carcinoma (HNSCC) and acute myeloid leukaemia cell lines, further corroborated in a HNSCC xenograft mouse model and through mining of publicly available DAC and paracetamol responses. In summary, the addition of paracetamol could allow for DAC dose reduction, widening its clinical usability and providing a strong rationale for consideration in cancer therapy.

cancer biology↗

bioRxiv2019

Transforming growth factor-beta signaling via ALK1 and ALK5 regulates distinct functional pathways in vein graft intimal hyperplasia

RationaleTransforming growth factor-beta (TGF{beta}) is tightly regulated at multiple levels, with regulation at the receptor level now recognized as a key determinant of the cellular response to this pleiotropic cytokine. TGF{beta} promotes saphenous vein graft neointima formation after coronary artery bypass graft (CABG) surgery, inducing smooth muscle cell (SMC) hyperplasia and fibrosis by signaling via activin receptor-like kinase 5(ALK5). However, the role of the alternate TGF{beta} receptor ALK1 remains completely unknown. ObjectiveTo define the receptor pathways activated by TGF{beta} in SMCs and their mechanistic importance during CABG neointima formation. Methods and resultsRadioligand co-IP assays revealed direct interactions between TGF{beta}, ALK5 and ALK1 in primary saphenous vein graft SMC (HSVSMC) from patients undergoing CABG. Knockdown and pharmacological inhibition of ALK5 or ALK1 in HSVSMC significantly attenuated TGF{beta}-induced phosphorylation of receptor-regulated (R)-Smads 2/3 and 1/5, respectively. Microarray profiling followed by qRT-PCR validation showed that TGF{beta} induced distinct transcriptional networks downstream of ALK5 or ALK1, associated with HSVSMC contractility and migration, respectively and confirmed using migration assays as well as qRT-PCR and western blot assays of contractile SMC markers. scRNAseq analysis of TGF{beta}-treated HSVSMC identified distinct subgroups of cells showing ALK5 or ALK1 transcriptional responses, while RNA velocity analyses indicated divergence in differentiation towards ALK5 or ALK1-dominant lineages. ALK1, ALK5 and their downstream effectors pSmad1/5 and pSmad2/3 were localized to SMA+ neointimal SMCs in remodelled mouse vein grafts. Pharmacological inhibition or genetic ablation of Smad1/5 substantially reducing neointima formation following acute vascular injury. Notably, expression and activation of ALK1, ALK5 and their respective downstream R-Smads was already evident in hyperplastic saphenous veins prior to grafting. ConclusionsWhilst canonical TGF{beta} signaling via ALK5 promotes a contractile HSVSMC phenotype, transactivation of ALK1 by TGF{beta} induces neointima formation by driving cell migration. Restoring the balance between ALK1 and ALK5 in HSVSMC may represent a novel therapeutic strategy for vein graft failure.

cell biology↗