👤 Kaspar W Persson

Atherosclerotic plaques are the leading cause of cardiovascular events. Single-cell approaches have identified diverse human plaque cell phenotypes but their spatial distribution and interactions remain unclear. Here, intercellular communication patterns in human plaque microenvironments were mapped to reveal novel targets to prevent atherosclerotic events. Spatial transcriptomics (Visium, 10x) from 13 carotid plaques, and single-cell transcriptomics (cells = 51 981) were used to analyse cell phenotypes, cell trajectories, and intercellular communications. Cells contributing to plaque stability were explored using deconvolution of plaque bulk RNA-seq data (n = 78), histology, and survival analyses. Key cells and pathways were validated in apolipoprotein E (Apoe)-/- mice and in vitro. Genome-wide association study enrichment analyses were conducted using summary statistics of atherosclerotic diseases. LINCS L1000 data were used to explore drug repurposing. A fibroblast-like vascular smooth muscle cell (VSMC) phenotype associated with extracellular matrix formation pathways (validated in Apoe-/- mice) emerged as a key regulator of intra-plaque ligand-receptor signalling, in particular in the cap region. A higher proportion of fibroblast-like VSMCs was found in asymptomatics, associated with stable plaque features and predicted a lower risk of future events. Genes specific to this VSMC phenotype were enriched in coronary artery disease and myocardial infarction. Finally, compounds, which could induce key marker genes were identified and validated in vitro. This study provides the first comprehensive spatial transcriptomics map of cell communication in human plaque microenvironments. A pivotal role of a fibroblast-like VSMC, orchestrating intraplaque cell signalling and contributing to plaque stability, was identified. Targeting these cells might present promising novel avenues for therapies. Show less

AMP-activated protein kinase (AMPK) and mechanistic target of rapamycin complex 1 (mTORC1) are crucial kinase signalling hubs that regulate the balance between catabolism and anabolism in skeletal muscle. The scaffold protein AXIN1 has been proposed to regulate the switch between these pathways and be required for GLUT4 translocation in skeletal muscle and adipocyte cell lines. Muscle-specific AXIN1 knockout (KO) mice exhibit no discernable phenotype, possibly due to compensation by AXIN2 upon AXIN1 loss. Thus we generated and characterized muscle-specific inducible AXIN1 and AXIN2 double knockout (dKO) mice. Surprisingly AXIN1/2 dKO mice displayed normal AMPK and mTORC1 signalling and glucose uptake in response to 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), insulin and in situ muscle contraction. These findings suggest that AXIN proteins are not essential for the regulation of AMPK and mTORC1 signalling or glucose uptake in skeletal muscle. This study challenges the previously indicated critical roles of AXIN1 in exercise-stimulated AMPK activation and GLUT4-mediated glucose uptake in skeletal muscle. KEY POINTS: Phenotyping of tamoxifen-inducible muscle-specific AXIN1/2 double knockout (dKO) mice. We find no evidence for AXIN-dependent AMPK or mTORC1 regulation in skeletal muscle by insulin, AMPK activation or contraction. Glucose uptake regulation by insulin and AMPK activation is normal in AXIN1/2 dKO mice. Show less

Tamoxifen-inducible skeletal muscle-specific AXIN1 knockout (AXIN1 imKO) in mouse does not affect whole-body energy substrate metabolism. AXIN1 imKO does not affect AICAR or insulin-stimulated glucose uptake in adult skeletal muscle. AXIN1 imKO does not affect adult skeletal muscle AMPK or mTORC1 signalling during AICAR/insulin/amino acid incubation, contraction and exercise. During exercise, α2/β2/γ3AMPK and AMP/ATP ratio show greater increases in AXIN1 imKO than wild-type in gastrocnemius muscle. AXIN1 is a scaffold protein known to interact with >20 proteins in signal transduction pathways regulating cellular development and function. Recently, AXIN1 was proposed to assemble a protein complex essential to catabolic-anabolic transition by coordinating AMPK activation and inactivation of mTORC1 and to regulate glucose uptake-stimulation by both AMPK and insulin. To investigate whether AXIN1 is permissive for adult skeletal muscle function, a phenotypic in vivo and ex vivo characterization of tamoxifen-inducible skeletal muscle-specific AXIN1 knockout (AXIN1 imKO) mice was conducted. AXIN1 imKO did not influence AMPK/mTORC1 signalling or glucose uptake stimulation at rest or in response to different exercise/contraction protocols, pharmacological AMPK activation, insulin or amino acids stimulation. The only genotypic difference observed was in exercising gastrocnemius muscle, where AXIN1 imKO displayed elevated α2/β2/γ3 AMPK activity and AMP/ATP ratio compared to wild-type mice. Our work shows that AXIN1 imKO generally does not affect skeletal muscle AMPK/mTORC1 signalling and glucose metabolism, probably due to functional redundancy of its homologue AXIN2. Show less

Evidence that glucose-dependent insulinotropic peptide (GIP) and/or the GIP receptor (GIPR) are involved in cardiovascular biology is emerging. We hypothesised that GIP has untoward effects on cardiovascular biology, in contrast to glucagon-like peptide 1 (GLP-1), and therefore investigated the effects of GIP and GLP-1 concentrations on cardiovascular disease (CVD) and mortality risk. GIP concentrations were successfully measured during OGTTs in two independent populations (Malmö Diet Cancer-Cardiovascular Cohort [MDC-CC] and Prevalence, Prediction and Prevention of Diabetes in Botnia [PPP-Botnia]) in a total of 8044 subjects. GLP-1 (n = 3625) was measured in MDC-CC. The incidence of CVD and mortality was assessed via national/regional registers or questionnaires. Further, a two-sample Mendelian randomisation (2SMR) analysis between the GIP pathway and outcomes (coronary artery disease [CAD] and myocardial infarction) was carried out using a GIP-associated genetic variant, rs1800437, as instrumental variable. An additional reverse 2SMR was performed with CAD as exposure variable and GIP as outcome variable, with the instrumental variables constructed from 114 known genetic risk variants for CAD. In meta-analyses, higher fasting levels of GIP were associated with risk of higher total mortality (HR[95% CI] = 1.22 [1.11, 1.35]; p = 4.5 × 10 In two prospective, community-based studies, elevated levels of GIP were associated with greater risk of all-cause and cardiovascular mortality within 5-9 years of follow-up, whereas GLP-1 levels were not associated with excess risk. Further studies are warranted to determine the cardiovascular effects of GIP per se. Show less

Heart failure affects 2-3% of adult Western population. Prevalence of heart failure with preserved left ventricular (LV) ejection fraction (HFpEF) increases. Studies suggest HFpEF patients to have altered myocardial structure and functional changes such as incomplete relaxation and increased cardiac stiffness. We hypothesised that patients undergoing elective coronary bypass surgery (CABG) with HFpEF characteristics would show distinctive gene expression compared to patients with normal LV physiology. Myocardial biopsies for mRNA expression analysis were obtained from sixteen patients with LV ejection fraction ≥45%. Five out of 16 patients (31%) had echocardiographic characteristics and increased NTproBNP levels indicative of HFpEF and this group was used as HFpEF proxy, while 11 patients had Normal LV physiology. Utilising principal component analysis, the gene expression data clustered into two groups, corresponding to HFpEF proxy and Normal physiology, and 743 differentially expressed genes were identified. The associated top biological functions were cardiac muscle contraction, oxidative phosphorylation, cellular remodelling and matrix organisation. Our results also indicate that upstream regulatory events, including inhibition of transcription factors STAT4, SRF and TP53, and activation of transcription repressors HEY2 and KDM5A, could provide explanatory mechanisms to observed gene expression differences and ultimately cardiac dysfunction in the HFpEF proxy group. Show less

The Merlin/NF2 tumor suppressor restrains cell growth and tumorigenesis by controlling contact-dependent inhibition of proliferation. We have identified a tight-junction-associated protein complex comprising Merlin, Angiomotin, Patj, and Pals1. We demonstrate that Angiomotin functions downstream of Merlin and upstream of Rich1, a small GTPase Activating Protein, as a positive regulator of Rac1. Merlin, through competitive binding to Angiomotin, releases Rich1 from the Angiomotin-inhibitory complex, allowing Rich1 to inactivate Rac1, ultimately leading to attenuation of Rac1 and Ras-MAPK pathways. Patient-derived Merlin mutants show diminished binding capacities to Angiomotin and are unable to dissociate Rich1 from Angiomotin or inhibit MAPK signaling. Depletion of Angiomotin in Nf2(-/-) Schwann cells attenuates the Ras-MAPK signaling pathway, impedes cellular proliferation in vitro and tumorigenesis in vivo. Show less

Controlled regulation of Rho GTPase activity is an essential component mediating growth factor-stimulated migration. We have previously shown that angiomotin (Amot), a membrane-associated scaffold protein, plays a critical role during vascular patterning and endothelial migration during embryogenesis. However, the signaling pathways by which Amot controls directional migration are not known. Here we have used peptide pull-down and yeast 2-hybrid (Y2H) screening to identify proteins that interact with the C-terminal PDZ-binding motifs of Amot and its related proteins AmotL1 and 2. We report that Amot and its related proteins bind to the RhoA GTPase exchange factor (RhoGEF) protein Syx. We show that Amot forms a ternary complex together with Patj (or its paralogue Mupp1) and Syx. Using FRET analysis, we provide evidence that Amot controls targeting of RhoA activity to lamellipodia in vitro. We also report that, similar to Amot, morpholino knockdown of Syx in zebrafish results in inhibition of migration of intersegmental arteries. Taken together, our results indicate that the directional migration of capillaries in the embryo is governed by the Amot:Patj/Mupp1:Syx signaling that controls local GTPase activity. Show less