Abstract Heart failure with preserved ejection fraction (HFpEF) is widely linked to endothelial dysfunction, yet the molecular pathways translating cardiometabolic stress into microvascular remodeling remain poorly defined. Here, we identify endothelial YAP/TAZ signaling as a mechanistic regulator of sex-divergent vascular responses in HFpEF. Plasma proteomics from the UK Biobank revealed elevated circulating YAP1 levels associated with heart failure and increased mortality, particularly in male patients, where YAP1 coincided with increased levels of the endothelial activation marker ESM1. In a hypertensive cardiorenal mouse model, endothelial YAP/TAZ deletion preserved cardiac function, whereas endothelial TAZ gain-of-function aggravated disease. Under cardiometabolic stress (TNFα and high glucose), endothelial cells exhibited sex-specific rewiring of YAP/TAZ-dependent transcriptional programs. Male endothelial cells showed increased extracellular YAP1 release, angiogenic instability with impaired extracellular matrix remodeling, whereas female cells adopted an immune-primed, stress-adaptive phenotype. Mechanistically, cardiometabolic stress uncoupled canonical YAP-TEAD transcription and engaged alternative cofactors, including VGLL3 and VGLL4, thereby reshaping the endothelial secretome and propagating sex-divergent microvascular remodeling. These findings identify endothelial YAP/TAZ rewiring as a molecular switch that converts cardiometabolic stress into sex-divergent microvascular remodeling in HFpEF and connect this process to circulating YAP1 and ESM1 in patients.

Cognitive deficits and brain glucose hypometabolism, lipid peroxidation and mitochondrial dysfunction are early pathological events in murine models and patients with Alzheimer’s disease (AD). Data from our previous research indicate that transgenic mice of the APP23 line, a murine AD model, exhibited higher energy expenditure and mitochondrial dysregulation in the liver as early as 3 months of age, which is considered the preplaque stage. Since women have a higher risk and mortality rate for AD, with potential sex-specific confounders as longevity, biological, genetic, and social factors also needing to be considered, sex differences in energy metabolism in AD remain insufficiently investigated. Here, we investigated sex-specific differences in mitochondrial respiration and metabolic profiles of 3–4-month-old, preplaque APP23 transgenic mice, in which we did not detect inflammatory signals and pathological amyloid-beta (Aß) plaques in brain or liver. Their mitochondrial respiration was assessed measuring oxygen consumption rates in isolated primary hepatocytes, stromal vascular cells (SVCs) and re-differentiated adipocytes. Furthermore, we analyzed energy balance, including food intake, locomotor activity, energy expenditure and fecal calorie loss. We observed an upregulation of hepatic mitochondrial respiration in preplaque APP23 females. Female-derived SVCs and differentiated adipocytes improved mitochondrial flexibility with palmitate loading in vitro, which was in line with decreased plasma triglycerides in preplaque APP23 females in vivo. However, no differences in mitochondrial respiration were detected in hepatocytes and re-differentiated adipocytes derived from male APP23 mice. Furthermore, we corroborated an increased mortality during the preplaque stage, particularly in females, which exhibited reduced hyperactivity and caloric intake before death compared to survivors. Our data demonstrate that preplaque APP23 female mice have disequilibrated mitochondrial oxidation in hepatocytes and adipocytes as well as higher energy expenditure due to increased activity before AD manifestation. In contrast, male APP23 mice did not exhibit such metabolic changes. Constant excessive energy loss and limited calorie supply potentially contribute to the higher risk of mortality, especially in APP23 females during young adulthood. Alzheimer’s disease (AD) affects men and women differently, with women at higher risk and mortality. This study explored sex differences in energy metabolism using APP23 transgenic mice, a model of AD, at young age (3–4 months) - before pathological amyloid-beta (Aß) plaques develop in the brain and liver. Female APP23 mice showed increased mitochondrial activity in liver and fat cells, higher energy expenditure, and more movement while eating less. They also excreted more energy in their feces. Notably, female APP23 mice had a lower survival rate than males. Before death, they became less active and ate even less, suggesting an inability to maintain energy balance. These findings indicate that female APP23 mice experience excessive energy loss, which may contribute to early mortality. Understanding these sex-specific metabolic differences could provide new insights into AD progression and highlight the need for targeted treatments. AD-related inflammatory signals and pathological Aβ plaques are virtually absent in the brain and liver of young APP23 mice in the preplaque stage. Preplaque APP23 transgenic female mice upregulate hepatic mitochondrial respiration, which is not observed in APP23 males. Ex vivo differentiated adipocytes isolated from preplaque APP23 females exhibit increased mitochondrial flexibility to fatty acid-induced metabolic stress. The preplaque APP23 females show increased activity with lower diet intake, while both sexes of APP23 mice have higher fecal energy loss compared to wild-type controls. The negative energy balance could contribute to the increased premature mortality of young APP23 mice in the preplaque stage.

Coronary arteries develop under constant mechanical stress. However, the role of mechanosensitive ion channels in this process remains poorly understood. Here we show that the ion channel PIEZO2, which responds to mechanical stimuli, is expressed in specific coronary endothelial cell populations during a critical phase of coronary vasculature remodeling. These Piezo2+ coronary endothelial cells show distinct transcriptional profiles and have mechanically activated ionic currents. Strikingly, PIEZO2 loss-of-function mouse embryos and mice with human pathogenic variants of PIEZO2 show abnormal coronary vessel development and cardiac left ventricular hyperplasia. We conclude that an optimal balance of PIEZO2 channel function contributes to proper coronary vessel formation, structural integrity and remodeling, and is likely to support normal cardiac function. Our study highlights the importance of mechanical cues in cardiovascular development and suggests that defects in this mechanosensing pathway may contribute to congenital heart conditions.

Journal Article Corrected proof A novel approach to modelling acute cardiac decompensation in rats Get access Arne Thiele, Arne Thiele Department of Nephrology and Internal Intensive Care Medicine, Charité-Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, GermanyExperimental and Clinical Research Center, Max Delbrück Center for Molecular Medicine, Charité-Universitätsmedizin Berlin, Lindenberger Weg 80, 13125 Berlin, GermanyDZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin, GermanyMax Delbrück Center for Molecular Medicine in the Helmholtz Association, Robert-Rössle Straße 10, 13125 Berlin, Germany https://orcid.org/0000-0003-0786-2239 Search for other works by this author on: Oxford Academic PubMed Google Scholar Hendrik Bartolomaeus, Hendrik Bartolomaeus Department of Nephrology and Internal Intensive Care Medicine, Charité-Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, GermanyExperimental and Clinical Research Center, Max Delbrück Center for Molecular Medicine, Charité-Universitätsmedizin Berlin, Lindenberger Weg 80, 13125 Berlin, GermanyDZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin, GermanyMax Delbrück Center for Molecular Medicine in the Helmholtz Association, Robert-Rössle Straße 10, 13125 Berlin, Germany Present address. Institute of Experimental Biomedicine, University Hospital Würzburg, Germany. https://orcid.org/0000-0003-4288-3828 Search for other works by this author on: Oxford Academic PubMed Google Scholar Harithaa Anandakumar, Harithaa Anandakumar Department of Nephrology and Internal Intensive Care Medicine, Charité-Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, GermanyExperimental and Clinical Research Center, Max Delbrück Center for Molecular Medicine, Charité-Universitätsmedizin Berlin, Lindenberger Weg 80, 13125 Berlin, GermanyDZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin, GermanyMax Delbrück Center for Molecular Medicine in the Helmholtz Association, Robert-Rössle Straße 10, 13125 Berlin, Germany https://orcid.org/0009-0000-3326-5126 Search for other works by this author on: Oxford Academic PubMed Google Scholar Nadine Haase, Nadine Haase Experimental and Clinical Research Center, Max Delbrück Center for Molecular Medicine, Charité-Universitätsmedizin Berlin, Lindenberger Weg 80, 13125 Berlin, GermanyDZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin, GermanyMax Delbrück Center for Molecular Medicine in the Helmholtz Association, Robert-Rössle Straße 10, 13125 Berlin, Germany https://orcid.org/0000-0003-0727-1738 Search for other works by this author on: Oxford Academic PubMed Google Scholar Arnd Heuser, Arnd Heuser Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Robert-Rössle Straße 10, 13125 Berlin, Germany https://orcid.org/0000-0002-3334-960X Search for other works by this author on: Oxford Academic PubMed Google Scholar Dominik N Müller, Dominik N Müller Experimental and Clinical Research Center, Max Delbrück Center for Molecular Medicine, Charité-Universitätsmedizin Berlin, Lindenberger Weg 80, 13125 Berlin, GermanyDZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin, GermanyMax Delbrück Center for Molecular Medicine in the Helmholtz Association, Robert-Rössle Straße 10, 13125 Berlin, Germany Search for other works by this author on: Oxford Academic PubMed Google Scholar Ralf Dechend, Ralf Dechend Experimental and Clinical Research Center, Max Delbrück Center for Molecular Medicine, Charité-Universitätsmedizin Berlin, Lindenberger Weg 80, 13125 Berlin, GermanyDZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin, GermanyMax Delbrück Center for Molecular Medicine in the Helmholtz Association, Robert-Rössle Straße 10, 13125 Berlin, GermanyDepartment of Cardiology and Nephrology, HELIOS-Klinikum, Schwanebecker Chaussee 50, 13125 Berlin, Germany https://orcid.org/0000-0001-6636-3080 Search for other works by this author on: Oxford Academic PubMed Google Scholar Nicola Wilck Nicola Wilck Department of Nephrology and Internal Intensive Care Medicine, Charité-Universitätsmedizin Berlin, Freie Universität Berlin and Humboldt-Universität zu Berlin, Charitéplatz 1, 10117 Berlin, GermanyExperimental and Clinical Research Center, Max Delbrück Center for Molecular Medicine, Charité-Universitätsmedizin Berlin, Lindenberger Weg 80, 13125 Berlin, GermanyDZHK (German Center for Cardiovascular Research), Partner Site Berlin, Berlin, GermanyMax Delbrück Center for Molecular Medicine in the Helmholtz Association, Robert-Rössle Straße 10, 13125 Berlin, Germany Corresponding author. Tel: +49 30 450 540 459; fax: +49 30 450 540 944, E-mail: [email protected] https://orcid.org/0000-0003-3189-5364 Search for other works by this author on: Oxford Academic PubMed Google Scholar Cardiovascular Research, cvae268, https://doi.org/10.1093/cvr/cvae268 Published: 06 January 2025 Article history Received: 06 September 2024 Revision received: 01 November 2024 Accepted: 05 December 2024 Published: 06 January 2025 Corrected and typeset: 10 January 2025

BACKGROUND: Accumulating evidence implicates the activation of G-protein–coupled PARs (protease-activated receptors) by coagulation proteases in the regulation of innate immune responses. METHODS: Using mouse models with genetic alterations of the PAR2 signaling platform, we have explored contributions of PAR2 signaling to infection with coxsackievirus B3, a single-stranded RNA virus provoking multiorgan tissue damage, including the heart. RESULTS: We show that PAR2 activation sustains correlates of severe morbidity—hemodynamic compromise, aggravated hypothermia, and hypoglycemia—despite intact control of the virus. Following acute viral liver injury, canonical PAR2 signaling impairs the restoration process associated with exaggerated type I IFN (interferon) signatures in response to viral RNA recognition. Metabolic profiling in combination with proteomics of liver tissue shows PAR2-dependent reprogramming of liver metabolism, increased lipid droplet storage, and gluconeogenesis. PAR2-sustained hypodynamic compromise, reprograming of liver metabolism, as well as imbalanced IFN responses are prevented in β-arrestin coupling-deficient PAR2 C-terminal phosphorylation mutant mice. Thus, wiring between upstream proteases and immune-metabolic responses results from biased PAR2 signaling mediated by intracellular recruitment of β-arrestin. Importantly, blockade of the TF (tissue factor)-FVIIa (coagulation factor VIIa) complex capable of PAR2 proteolysis with the NAPc2 (nematode anticoagulant protein c2) mitigated virus-triggered pathology, recapitulating effects seen in protease cleavage-resistant PAR2 mice. CONCLUSIONS: These data provide insights into a TF-FVIIa signaling axis through PAR2-β-arrestin coupling that is a regulator of inflammation-triggered tissue repair and hemodynamic compromise in coxsackievirus B3 infection and can potentially be targeted with selective coagulation inhibitors.

The importance of microvascular imaging in diagnosis and therapeutic targeting of various diseases is increasingly recognized. The new approach emphasizes the need for holistic studies to understand the inter-organ vascular cross-talk. Here, we report on the development of a novel perfusion protocol which consistently delivers a micro-computed tomography contrast agent to micro-vessels of multiple organs in a single experimental animal. We describe the achieved repeatability of the perfusions, as well as the image analysis steps developed individually for each organ type. We also optimize image acquisition by investigating the compromise between shortening of the scanning time and preservation of the highest possible spatial resolution. Taking together, with the multi-organ perfusion, optimized image acquisition, and the conceived image analysis steps, we provide a comprehensive and reliable experimental protocol for studying vascular morphology and pathology in multi-organ diseases.

AIMS:Mutation of the PRDM16 gene causes human dilated and non-compaction cardiomyopathy. The PRDM16 protein is a transcriptional regulator that affects cardiac development via Tbx5 and Hand1, thus regulating myocardial structure. The biallelic inactivation of Prdm16 induces severe cardiac dysfunction with post-natal lethality and hypertrophy in mice. The early pathological events that occur upon Prdm16 inactivation have not been explored. METHODS AND RESULTS:This study performed in-depth pathophysiological and molecular analyses of male and female Prdm16csp1/wt mice that carry systemic, monoallelic Prdm16 gene inactivation. We systematically assessed early molecular changes through transcriptomics, proteomics, and metabolomics. Kinetic modelling of cardiac metabolism was performed in silico with CARDIOKIN. Prdm16csp1/wt mice are viable up to 8 months, develop hypoplastic hearts, and diminished systolic performance that is more pronounced in female mice. Prdm16csp1/wt cardiac tissue of both sexes showed reductions in metabolites associated with amino acid as well as glycerol metabolism, glycolysis, and the tricarboxylic acid cycle. Prdm16csp1/wt cardiac tissue revealed diminished glutathione (GSH) and increased inosine monophosphate (IMP) levels indicating oxidative stress and a dysregulated energetics, respectively. An accumulation of triacylglycerides exclusively in male Prdm16csp1/wt hearts suggests a sex-specific metabolic adaptation. Metabolic modelling using CARDIOKIN identified a reduction in fatty acid utilization in males as well as lower glucose utilization in female Prdm16csp1/wt cardiac tissue. On the level of transcripts and protein expression, Prdm16csp1/wt hearts demonstrate an up-regulation of pyridine nucleotide-disulphide oxidoreductase domain 2 (Pyroxd2) and the transcriptional regulator pre-B-cell leukaemia transcription factor interacting protein 1 (Pbxip1). The strongest concordant transcriptional up-regulation was detected for Prdm16 itself, probably through an autoregulatory mechanism. CONCLUSIONS:Monoallelic, global Prdm16 mutation diminishes cardiac performance in Prdm16csp1/wt mice. Metabolic alterations and transcriptional dysregulation in Prdm16csp1/wt affect cardiac tissue. Female Prdm16csp1/wt mice develop a more pronounced phenotype, indicating sexual dimorphism at this early pathological window. This study suggests that metabolic dysregulation is an early event in the PRDM16 associated cardiac pathology.

Desmosomes are intercellular adhesion complexes providing mechanical coupling and tissue integrity. Previously, a correlation of desmosomal molecule expression with invasion and metastasis formation in several tumor entities was described together with a relevance for circulating tumor cell cluster formation. Here, we investigated the contribution of the desmosomal core adhesion molecule desmoglein-2 (DSG2) to the initial steps of liver metastasis formation by pancreatic cancer cells using a novel ex vivo liver perfusion mouse model. We applied the pancreatic ductal adenocarcinoma cell line AsPC-1 with and without a knockout (KO) of DSG2 and generated mouse lines with a hepatocyte-specific KO of the known interacting partners of DSG2 (DSG2 and desmocollin-2). Liver perfusion with DSG2 KO AsPC-1 cells led to smaller circulating cell clusters and a reduced number of cells adhering to murine livers compared to control cells. While this was independent of the expression levels of desmosomal adhesion molecules in hepatocytes, we show that increased cluster size of cancer cells, which correlates with stronger cell-cell adhesion and expression of desmosomal molecules, is a major factor contributing to the early phase of metastatic spreading. In conclusion, impaired desmosomal adhesion results in reduced circulating cell cluster size, which is relevant for seeding and attachment of metastatic cells to the liver.

Aims Virus infection triggers inflammation and, may impose nutrient shortage to the heart. Supported by type I interferon (IFN) signalling, cardiomyocytes counteract infection by various effector processes, with the IFN-stimulated gene of 15 kDa (ISG15) system being intensively regulated and protein modification with ISG15 protecting mice Coxsackievirus B3 (CVB3) infection. The underlying molecular aspects how the ISG15 system affects the functional properties of respective protein substrates in the heart are unknown.Methods and results Based on the protective properties due to protein ISGylation, we set out a study investigating CVB3-infected mice in depth and found cardiac atrophy with lower cardiac output in ISG15-/- mice. By mass spectrometry, we identified the protein targets of the ISG15 conjugation machinery in heart tissue and explored how ISGylation affects their function. The cardiac ISGylome showed a strong enrichment of ISGylation substrates within glycolytic metabolic processes. Two control enzymes of the glycolytic pathway, hexokinase 2 (HK2) and phosphofructokinase muscle form (PFK1), were identified as bona fide ISGylation targets during infection. In an integrative approach complemented with enzymatic functional testing and structural modelling, we demonstrate that protein ISGylation obstructs the activity of HK2 and PFK1. Seahorse-based investigation of glycolysis in cardiomyocytes revealed that, by conjugating proteins, the ISG15 system prevents the infection-/IFN-induced up-regulation of glycolysis. We complemented our analysis with proteomics-based advanced computational modelling of cardiac energy metabolism. Our calculations revealed an ISG15-dependent preservation of the metabolic capacity in cardiac tissue during CVB3 infection. Functional profiling of mitochondrial respiration in cardiomyocytes and mouse heart tissue by Seahorse technology showed an enhanced oxidative activity in cells with a competent ISG15 system.Conclusion Our study demonstrates that ISG15 controls critical nodes in cardiac metabolism. ISG15 reduces the glucose demand, supports higher ATP production capacity in the heart, despite nutrient shortage in infection, and counteracts cardiac atrophy and dysfunction. Graphical Abstract

The coronary arteries develop under substantial mechanical loads. However, the role of mechanosensitive ion channels has barely been addressed in this system. Here we demonstrate the expression of the mechanosensitive ion channel PIEZO2 in specific coronary endothelial cell populations during a crucial phase of vascular modeling. Piezo2 positive coronary endothelial cells display distinct transcriptional profiles and have mechanically activated ionic currents. Strikingly, Piezo2-/- mouse embryos and mice with human pathogenic variants of PIEZO2 display coronary vessel malformations and left ventricular hyperplasia. We conclude that an optimal balance of PIEZO2 channel function is indispensable for coronary vessel formation, integrity, and remodeling and likely for proper cardiac function. ### Competing Interest Statement The authors have declared no competing interest.

The coxsackievirus and adenovirus receptor (CAR) mediates homo- and heterotopic interactions between neighboring cardiomyocytes at the intercalated disc. CAR is upregulated in the hypoxic areas surrounding myocardial infarction (MI). To elucidate whether CAR contributes to hypoxia signaling and MI pathology, we used a gain- and loss-of-function approach in transfected HEK293 cells, H9c2 cardiomyocytes and CAR knockout mice. CAR overexpression increased RhoA activity, HIF-1α expression and cell death in response to chemical and physical hypoxia. In vivo, we subjected cardiomyocyte-specific CAR knockout (KO) and wild-type mice (WT) to coronary artery ligation. Survival was drastically improved in KO mice with largely preserved cardiac function as determined by echocardiography. Histological analysis revealed a less fibrotic, more compact lesion. Thirty days after MI, there was no compensatory hypertrophy or reduced cardiac output in hearts from CAR KO mice, in contrast to control mice with increased heart weight and reduced ejection fraction as signs of the underlying pathology. Based on these findings, we suggest CAR as a therapeutic target for the improved future treatment or prevention of myocardial infarction.

Background: Phosphodiesterase 3A ( PDE3A ) gain-of-function mutations cause hypertension with brachydactyly (HTNB) and lead to stroke. Increased peripheral vascular resistance, rather than salt retention, is responsible. It is surprising that the few patients with HTNB examined so far did not develop cardiac hypertrophy or heart failure. We hypothesized that, in the heart, PDE3A mutations could be protective. Methods: We studied new patients. CRISPR-Cas9–engineered rat HTNB models were phenotyped by telemetric blood pressure measurements, echocardiography, microcomputed tomography, RNA-sequencing, and single nuclei RNA-sequencing. Human induced pluripotent stem cells carrying PDE3A mutations were established, differentiated to cardiomyocytes, and analyzed by Ca 2+ imaging. We used Förster resonance energy transfer and biochemical assays. Results: We identified a new PDE3A mutation in a family with HTNB. It maps to exon 13 encoding the enzyme’s catalytic domain. All hitherto identified HTNB PDE3A mutations cluster in exon 4 encoding a region N-terminally from the catalytic domain of the enzyme. The mutations were recapitulated in rat models. Both exon 4 and 13 mutations led to aberrant phosphorylation, hyperactivity, and increased PDE3A enzyme self-assembly. The left ventricles of our patients with HTNB and the rat models were normal despite preexisting hypertension. A catecholamine challenge elicited cardiac hypertrophy in HTNB rats only to the level of wild-type rats and improved the contractility of the mutant hearts, compared with wild-type rats. The β-adrenergic system, phosphodiesterase activity, and cAMP levels in the mutant hearts resembled wild-type hearts, whereas phospholamban phosphorylation was decreased in the mutants. In our induced pluripotent stem cell cardiomyocyte models, the PDE3A mutations caused adaptive changes of Ca 2+ cycling. RNA-sequencing and single nuclei RNA-sequencing identified differences in mRNA expression between wild-type and mutants, affecting, among others, metabolism and protein folding. Conclusions: Although in vascular smooth muscle, PDE3A mutations cause hypertension, they confer protection against hypertension-induced cardiac damage in hearts. Nonselective PDE3A inhibition is a final, short-term option in heart failure treatment to increase cardiac cAMP and improve contractility. Our data argue that mimicking the effect of PDE3A mutations in the heart rather than nonselective PDE3 inhibition is cardioprotective in the long term. Our findings could facilitate the search for new treatments to prevent hypertension-induced cardiac damage.

Task-free functional connectivity in animal models provides an experimental framework to examine connectivity phenomena under controlled conditions and allows for comparisons with data modalities collected under invasive or terminal procedures. Currently, animal acquisitions are performed with varying protocols and analyses that hamper result comparison and integration. Here we introduce StandardRat, a consensus rat functional magnetic resonance imaging acquisition protocol tested across 20 centers. To develop this protocol with optimized acquisition and processing parameters, we initially aggregated 65 functional imaging datasets acquired from rats across 46 centers. We developed a reproducible pipeline for analyzing rat data acquired with diverse protocols and determined experimental and processing parameters associated with the robust detection of functional connectivity across centers. We show that the standardized protocol enhances biologically plausible functional connectivity patterns relative to previous acquisitions. The protocol and processing pipeline described here is openly shared with the neuroimaging community to promote interoperability and cooperation toward tackling the most important challenges in neuroscience. The authors pooled resources to identify best practices and develop a new standardized protocol for estimating functional connectivity in rats with magnetic resonance imaging.

Multiple myeloma (MM), a tumor of germinal center (GC)-experienced plasma cells, comprises distinct genetic subgroups, such as the t(11;14)/CCND1 and the t(4;14)/MMSET subtype. We have generated genetically defined, subgroup-specific MM models by the GC B cell-specific coactivation of mouse Ccnd1 or MMSET with a constitutively active Ikk2 mutant, mimicking the secondary NF-κB activation frequently seen in human MM. Ccnd1/Ikk2ca and MMSET/Ikk2ca mice developed a pronounced, clonally restricted plasma cell outgrowth with age, accompanied by serum M spikes, bone marrow insufficiency, and bone lesions. The transgenic plasma cells could be propagated in vivo and showed distinct transcriptional profiles, resembling their human MM counterparts. Thus, we show that targeting the expression of genes involved in MM subgroup-specific chromosomal translocations into mouse GC B cells translates into distinct MM-like diseases that recapitulate key features of the human tumors, opening the way to a better understanding of the pathogenesis and therapeutic vulnerabilities of different MM subgroups.

AMPA-type glutamate receptors (AMPARs) mediate fast excitatory neurotransmission, and the plastic modulation of their surface levels determines synaptic strength. AMPARs of different subunit compositions fulfill distinct roles in synaptic long-term potentiation (LTP) and depression (LTD) to enable learning. Largely unknown endocytic mechanisms mediate the subunit-selective regulation of the surface levels of GluA1-homomeric Ca 2+ -permeable (CP) versus heteromeric Ca 2+ -impermeable (CI) AMPARs. Here, we report that the Alzheimer’s disease risk factor CALM controls the surface levels of CP-AMPARs and thereby reciprocally regulates LTP and LTD in vivo to modulate learning. We show that CALM selectively facilitates the endocytosis of ubiquitinated CP-AMPARs via a mechanism that depends on ubiquitin recognition by its ANTH domain but is independent of clathrin. Our data identify CALM and related ANTH domain–containing proteins as the core endocytic machinery that determines the surface levels of CP-AMPARs to bidirectionally control synaptic plasticity and modulate learning in the mammalian brain.

Task-free functional connectivity in animal models provides an experimental framework to examine connectivity phenomena under controlled conditions and allows comparison with invasive or terminal procedures. To date, animal acquisitions are performed with varying protocols and analyses that hamper result comparison and integration. We introduce StandardRat , a consensus rat functional MRI acquisition protocol tested across 20 centers. To develop this protocol with optimized acquisition and processing parameters, we initially aggregated 65 functional imaging datasets acquired in rats from 46 centers. We developed a reproducible pipeline for the analysis of rat data acquired with diverse protocols and determined experimental and processing parameters associated with a more robust functional connectivity detection. We show that the standardized protocol enhances biologically plausible functional connectivity patterns, relative to pre-existing acquisitions. The protocol and processing pipeline described here are openly shared with the neuroimaging community to promote interoperability and cooperation towards tackling the most important challenges in neuroscience.

AbstractBackgroundAging is associated with a progressive reduction in cellular function leading to poor health and loss of physical performance. Mitochondrial dysfunction is one of the hallmarks of aging; hence, interventions targeting mitochondrial dysfunction have the potential to provide preventive and therapeutic benefits to elderly individuals. Meta‐analyses of age‐related gene expression profiles showed that the expression of Ahnak1, a protein regulating several signal‐transduction pathways including metabolic homeostasis, is increased with age, which is associated with low VO2MAX and poor muscle fitness. However, the role of Ahnak1 in the aging process remained unknown. Here, we investigated the age‐related role of Ahnak1 in murine exercise capacity, mitochondrial function, and contractile function of cardiac and skeletal muscles.MethodsWe employed 15‐ to 16‐month‐old female and male Ahnak1‐knockout (Ahnak1‐KO) and wild‐type (WT) mice and performed morphometric, biochemical, and bioenergetics assays to evaluate the effects of Ahnak1 on exercise capacity and mitochondrial morphology and function in cardiomyocytes and tibialis anterior (TA) muscle. A human left ventricular (LV) cardiomyocyte cell line (AC16) was used to investigate the direct role of Ahnak1 in cardiomyocytes.ResultsWe found that the level of Ahnak1 protein is significantly up‐regulated with age in the murine LV (1.9‐fold) and TA (1.8‐fold) tissues. The suppression of Ahnak1 was associated with improved exercise tolerance, as all aged adult Ahnak1‐KO mice (100%) successfully completed the running programme, whereas approximately 31% male and 8% female WT mice could maintain the required running speed and distance. Transmission electron microscopic studies showed that LV and TA tissue specimens of aged adult Ahnak1‐KO of both sexes have significantly more enlarged/elongated mitochondria and less small mitochondria compared with WT littermates (P < 0.01 and P < 0.001, respectively) at basal level. Further, we observed a shift in mitochondrial fission/fusion balance towards fusion in cardiomyocytes and TA muscle from aged adult Ahnak1‐KO mice. The maximal and reserve respiratory capacities were significantly higher in cardiomyocytes from aged adult Ahnak1‐KO mice compared with the WT counterparts (P < 0.05 and P < 0.01, respectively). Cardiomyocyte contractility and fatigue resistance of TA muscles were significantly increased in Ahnak1‐KO mice of both sexes, compared with the WT groups. In vitro studies using AC16 cells have confirmed that the alteration of mitochondrial function is indeed a direct effect of Ahnak1. Finally, we presented Ahnak1 as a novel cardiac mitochondrial membrane‐associated protein.ConclusionsOur data suggest that Ahnak1 is involved in age‐related cardiac and skeletal muscle dysfunction and could therefore serve as a promising therapeutical target.

To establish the first protocol for high-resolution three-dimensional imaging of multiple organs in rodents, we performed microvasculature casting with Microfil silicone rubber substance in non-living rats and combined the method with advanced image analysis protocols after micro-CT scanning. This newly established method allows changes in individual organs to be visualized and examined in extraordinary detail as part of a multi-organ approach. Previously published protocols only address visualization of single organs or are insufficiently resolved with respect to vessel diameter analysis. With optimized staining protocols, samples can additionally be examined for possible structural changes such as inflammatory processes or fibrotic formation. Preeclampsia is a condition during pregnancy that leads to up to a 4-fold increased risk of maternal cardiovascular disease later in life, although symptoms usually resolve after delivery. In former preeclamptic rats, a reduction in microvascular density in the heart and brain with a simultaneous increase in retinal vessels has been described, even weeks after the disappearance of major features such as hypertension and albuminuria. The technique described will enhance studies of the vasculature in many other animal models and provide striking insights into vascular physiology necessary to drive translation.