LANCL1 binds abscisic acid and stimulates glucose transport and mitochondrial respiration in muscle cells via the AMPK/PGC-1α/Sirt1 pathway

Objective: Abscisic acid (ABA) is a plant hormone also present and active in animals. In mammals, ABA regulates blood glucose levels by stimulating insulin-independent glucose uptake and metabolism in adipocytes and myocytes through its receptor LANCL2. The objective of this study was to investigate whether another member of the LANCL protein family, LANCL1, also behaves as an ABA receptor and, if so, which functional effects are mediated by LANCL1. Methods: ABA binding to human recombinant LANCL1 was explored by equilibrium-binding experiments with [3H]ABA, circular dichroism, and surface plasmon resonance. Rat L6 myoblasts overexpressing either LANCL1 or LANCL2, or silenced for the expression of both proteins, were used to investigate the basal and ABA-stimulated transport of a fluorescent glucose analog (NBDG) and the signaling pathway downstream of the LANCL proteins using Western blot and qPCR analysis. Finally, glucose tolerance and sensitivity to ABA were compared in LANCL2−/− and wild-type (WT) siblings. Results: Human recombinant LANCL1 binds ABA with a Kd between 1 and 10 μM, depending on the assay (i.e., in a concentration range that lies between the low and high-affinity ABA binding sites of LANCL2). In L6 myoblasts, LANCL1 and LANCL2 similarly, i) stimulate both basal and ABA-triggered NBDG uptake (4-fold), ii) activate the transcription and protein expression of the glucose transporters GLUT4 and GLUT1 (4-6-fold) and the signaling proteins AMPK/PGC-1α/Sirt1 (2-fold), iii) stimulate mitochondrial respiration (5-fold) and the expression of the skeletal muscle (SM) uncoupling proteins sarcolipin (3-fold) and UCP3 (12-fold). LANCL2−/− mice have a reduced glucose tolerance compared to WT. They spontaneously overexpress LANCL1 in the SM and respond to chronic ABA treatment (1 μg/kg body weight/day) with an improved glycemia response to glucose load and an increased SM transcription of GLUT4 and GLUT1 (20-fold) of the AMPK/PGC-1α/Sirt1 pathway and sarcolipin, UCP3, and NAMPT (4- to 6-fold). Conclusions: LANCL1 behaves as an ABA receptor with a somewhat lower affinity for ABA than LANCL2 but with overlapping effector functions: stimulating glucose uptake and the expression of muscle glucose transporters and mitochondrial uncoupling and respiration via the AMPK/PGC-1α/Sirt1 pathway. Receptor redundancy may have been advantageous in animal evolution, given the role of the ABA/LANCL system in the insulin-independent stimulation of cell glucose uptake and energy metabolism

Single-molecule imaging and molecular dynamics simulations reveal early activation of the MET receptor in cells

Embedding of cell-surface receptors into a membrane defines their dynamics but also complicates experimental characterization of their signaling complexes. The hepatocyte growth factor receptor MET is a receptor tyrosine kinase involved in cellular processes such as proliferation, migration, and survival. It is also targeted by the pathogen Listeria monocytogenes, whose invasion protein, internalin B (InlB), binds to MET, forming a signaling dimer that triggers pathogen internalization. Here we use an integrative structural biology approach, combining molecular dynamics simulations and single-molecule Förster resonance energy transfer (smFRET) in cells, to investigate the early stages of MET activation. Our simulations show that InlB binding stabilizes MET in a conformation that promotes dimer formation. smFRET reveals that the in situ dimer structure closely resembles one of two previously published crystal structures, though with key differences. This study refines our understanding of MET activation and provides a methodological framework for studying other plasma membrane receptors

Peptides inhibiting the assembly of monomeric human l-lactate dehydrogenase into catalytically active homotetramer decrease the synthesis of lactate in cultured cells

The energetic metabolism of cancer cells relies on a substantial commitment of pyruvate to the catalytic action of lactate-generating dehydrogenases. This coupling mainly depends on lactate dehydrogenase A (LDH-A), which is overexpressed in different types of cancers, and therefore represents an appealing therapeutic target. Taking into account that the activity of LDHs is exclusively exerted by their tetrameric forms, it was recently shown that peptides perturbing the monomers-to-tetramer assembly inhibit human LDH-A (hLDH-A). However, to identify these peptides, tetrameric hLDH-A was transiently exposed to strongly acidic conditions inducing its dissociation into monomers, which were tested as a target for peptides at low pH. Nevertheless, the availability of native monomeric hLDH-A would allow performing similar screenings under physiological conditions. Here we report on the unprecedented isolation of recombinant monomeric hLDH-A at neutral pH, and on its use to identify peptides inhibiting the assembly of the tetrameric enzyme. Remarkably, the GQNGISDL octapeptide, mimicking the 296–303 portion of hLDH-A C-terminal region, was observed to effectively inhibit the target enzyme. Moreover, by dissecting the action of this octapeptide, the cGQND cyclic tetrapeptide was found to act as the parental compound. Furthermore, we performed assays using MCF7 and BxPC3 cultured cells, exclusively expressing hLDH-A and hLDH-B, respectively. By means of these assays we detected a selective action of linear and cyclic GQND tetrapeptides, inhibiting lactate secretion in MCF7 cells only. Overall, our observations suggest that peptides mimicking the C-terminal region of hLDH-A effectively interfere with protein–protein interactions responsible for the assembly of the tetrameric enzyme

Side-by-side comparison of uPAR-targeting optical imaging antibodies and antibody fragments for fluorescence-guided surgery of solid tumors

Purpose Radical resection is paramount for curative oncological surgery. Fluorescence-guided surgery (FGS) aids in intraoperative identification of tumor-positive resection margins. This study aims to assess the feasibility of urokinase plasminogen activator receptor (uPAR) targeting antibody fragments for FGS in a direct comparison with their parent IgG in various relevant in vivo models. Procedures Humanized anti-uPAR monoclonal antibody MNPR-101 (uIgG) was proteolytically digested into F(ab')2 and Fab fragments named uFab2 and uFab. Surface plasmon resonance (SPR) and cell assays were used to determine in vitro binding before and after fluorescent labeling with IRDye800CW. Mice bearing subcutaneous HT-29 human colonic cancer cells were imaged serially for up to 120 h after fluorescent tracer administration. Imaging characteristics and ex vivo organ biodistribution were further compared in orthotopic pancreatic ductal adenocarcinoma (BxPc-3-luc2), head-and-neck squamous cell carcinoma (OSC-19-luc2-GFP), and peritoneal carcinomatosis (HT29-luc2) models using the clinical Artemis fluorescence imaging system. Results Unconjugated and conjugated uIgG, uFab2, and uFab specifically recognized uPAR in the nanomolar range as determined by SPR and cell assays. Subcutaneous tumors were clearly identifiable with tumor-to-background ratios (TBRs) > 2 after 72 h for uIgG-800F and 24 h for uFab2-800F and uFab-800F. For the latter two, mean fluorescence intensities (MFIs) dipped below predetermined threshold after 72 h and 36 h, respectively. Tumors were easily identified in the orthotopic models with uIgG-800F consistently having the highest MFIs and uFab2-800F and uFab-800F having similar values. In biodistribution studies, kidney and liver fluorescence approached tumor fluorescence after uIgG-800F administration and surpassed tumor fluorescence after uFab2-800F or uFab-800F administration, resulting in interference in the abdominal orthotopic mouse models. Conclusions In a side-by-side comparison, FGS with uPAR-targeting antibody fragments compared with the parent IgG resulted in earlier tumor visualization at the expense of peak fluorescence intensity.Surgical oncolog

A multimodal molecular imaging approach targeting urokinase plasminogen activator receptor for the diagnosis, resection and surveillance of urothelial cell carcinoma

With a 5-year recurrence rate of 30-78%, urothelial cell carcinoma (UCC) rates amongst the highest of all solid malignancies. Consequently, after transurethral resection, patients are subjugated to life-long endoscopic surveillance. A multimodal near-infrared (NIR) fluorescence-based imaging strategy can improve diagnosis, resection and surveillance, hence increasing quality of life.Methods: Expression of urokinase plasminogen activator receptor (uPAR) and epithelial cell adhesion molecule (EpCAM) are determined on paraffin-embedded human UCC using immunohistochemistry and on UCC cell lines by flow cytometry. MNPR-101, a humanised monoclonal antibody targeting uPAR is conjugated to IRDye800CW and binding is validated in vitro using surface plasmon resonance and cell-based binding assays. In vivo NIR fluorescence and photoacoustic three-dimensional (3D) imaging are performed with subcutaneously growing human UM-UC-31uc2 cells in BALB/c-nude mice. The translational potential is confirmed in a metastasising UM-UC-31uc2 orthotopic mouse model. InfliximabIRDye800CW and rituximab-IRDye800CW are used as controls.Results: UCCs show prominent uPAR expression at the tumour-stroma interface and EpCAM on epithelial cells. uPAR and EpCAM are expressed by 6/7 and 4/7 UCC cell lines, respectively. In vitro, MNPR-101-IRDye800CW has a picomolar affinity for domain 2-3 of uPAR. In vivo fluorescence imaging with MNPR-101-IRDye800CW, specifically delineates both subcutaneous and orthotopic tumours with tumour-to-background ratios reaching as high as 6.8, differing significantly from controls (p < 0.0001). Photoacoustic 3D in depth imaging confirms the homogenous distribution of MNPR-101-IRDye800CW through the tumour.Conclusions: MNPR-101-IRDye800CW is suitable for multimodal imaging of UCC, awaiting clinical translation. (C) 2021 The Author(s). Published by Elsevier Ltd.Surgical oncolog

Frequency of left ventricular hypertrophy in non-valvular atrial fibrillation

Left ventricular hypertrophy (LVH) is significantly related to adverse clinical outcomes in patients at high risk of cardiovascular events. In patients with atrial fibrillation (AF), data on LVH, that is, prevalence and determinants, are inconsistent mainly because of different definitions and heterogeneity of study populations. We determined echocardiographic-based LVH prevalence and clinical factors independently associated with its development in a prospective cohort of patients with non-valvular (NV) AF. From the "Atrial Fibrillation Registry for Ankle-brachial Index Prevalence Assessment: Collaborative Italian Study" (ARAPACIS) population, 1,184 patients with NVAF (mean age 72 \ub1 11 years; 56% men) with complete data to define LVH were selected. ARAPACIS is a multicenter, observational, prospective, longitudinal on-going study designed to estimate prevalence of peripheral artery disease in patients with NVAF. We found a high prevalence of LVH (52%) in patients with NVAF. Compared to those without LVH, patients with AF with LVH were older and had a higher prevalence of hypertension, diabetes, and previous myocardial infarction (MI). A higher prevalence of ankle-brachial index 640.90 was seen in patients with LVH (22 vs 17%, p = 0.0392). Patients with LVH were at significantly higher thromboembolic risk, with CHA2DS2-VASc 652 seen in 93% of LVH and in 73% of patients without LVH (p &lt;0.05). Women with LVH had a higher prevalence of concentric hypertrophy than men (46% vs 29%, p = 0.0003). Logistic regression analysis demonstrated that female gender (odds ratio [OR] 2.80, p &lt;0.0001), age (OR 1.03 per year, p &lt;0.001), hypertension (OR 2.30, p &lt;0.001), diabetes (OR 1.62, p = 0.004), and previous MI (OR 1.96, p = 0.001) were independently associated with LVH. In conclusion, patients with NVAF have a high prevalence of LVH, which is related to female gender, older age, hypertension, and previous MI. These patients are at high thromboembolic risk and deserve a holistic approach to cardiovascular prevention

Antibody-drug conjugates: targeted weapons against cancer

Antibody drug conjugates (ADCs) are formed by a targeting antibody conjugated to a chemotherapeutic molecule through a linker. Recent data demonstrate that they represent a valuable advancement for the clinics and, despite their recent appearance, they are already undergoing an innovation wave aimed at targeting all their three building blocks. Thus, new antibody formats are being engineered, site-specific linkers are being designed and highly toxic molecules, like RNA polymerase inhibitors, start to be used for conjugation. These molecules were previously considered extremely toxic and could not be used as chemotherapeutic drugs. In this review, we will go through an overview of current cancer treatments and their limitations, and the logic which has led to the generation of ADCs. Their mechanism of action will be outlined and the most recent novelties in linker design and optimization will be discussed, along with present and near future of the current ADC pipeline