ArreSTick motif controls ß-arrestin-binding stability and extends phosphorylation-dependent ß-arrestin interactions to non-receptor proteins.

The binding and function of ß-arrestins are regulated by specific phosphorylation motifs present in G protein-coupled receptors (GPCRs). However, the exact arrangement of phosphorylated amino acids responsible for establishing a stable interaction remains unclear. We employ a 1D sequence convolution model trained on GPCRs with established ß-arrestin-binding properties. With this approach, amino acid motifs characteristic of GPCRs that form stable interactions with ß-arrestins can be identified, a pattern that we name "arreSTick." Intriguingly, the arreSTick pattern is also present in numerous non-receptor proteins. Using proximity biotinylation assay and mass spectrometry analysis, we demonstrate that the arreSTick motif controls the interaction between many non-receptor proteins and ß-arrestin2. The HIV-1 Tat-specific factor 1 (HTSF1 or HTATSF1), a nuclear transcription factor, contains the arreSTick pattern, and its subcellular localization is influenced by ß-arrestin2. Our findings unveil a broader role for ß-arrestins in phosphorylation-dependent interactions, extending beyond GPCRs to encompass non-receptor proteins as well.

[How did the survival of acute myeloid leukemia change over the last ten years in our unit?] / Hogyan változott az akut myeloid leukaemiás betegek túlélése a terápiás lehetoségek bovülésével az elmúlt 10 évben klinikánkon?

INTRODUCTION: Acute myeloid leukemia (AML) is a hematological malignancy with high mortality rate. The treatment is especially challenging in patients older than 65 years, which is the large majority of those. For patients unfit for intensive chemotherapy regimens, only palliative cytoreduction and basic supportive care used to be the options in our unit. However, from 2018, the azacitidine-venetoclax combination has been a new therapeutic alternative. This treatment resulted in marked survival benefit in clinical trials, however, its impact on the daily clinical practice and the entire patient population is unclear. OBJECTIVE: Our goal was to evaluate how the application of azacitidine-venetoclax changed the treatment and survival of AML patients in our practice. METHOD: We retrospectively analyzed the available clinical data of all AML patients treated consecutively between January 1, 2011 and December 31, 2021 at the 3rd Department of Internal Medicine (from 2020 onward called Department of Internal Medicine and Hematology), examining their treatment depending on the time period of therapy (2011-2017 and 2018-2021). Patients with acute promyelocytic leukemia were excluded. RESULTS: 423 patients were diagnosed during this period. The number of cases showed a marked increase: in the first 7 years of our study, 184 patients were diagnosed, while this rose to 239 during the subsequent 4 years. The median age of patients was 67.6 years, with more than 60% of patients aged over 65. An improving trend can be observed in the overall survival: between 2011 and 2017, the median overall survival was 4.8 ± 0.9 months, while between 2018 and 2021, it was 8.3 ± 1.4 months (p = 0.051). Moreover, in the case of patients over 65 there was a significant overall survival improvement: 3.1 ± 0.5 vs. 4.9 ± 0.6 months (p = 0,01). The main factor behind this improvement could be that a large proportion of over 65 patients previously only fit for supportive care could now be treated with azacitidine-venetoclax: the percentage of actively treated patients grew from 57.1% to 75.3% in the second period. CONCLUSION: The survival of patients unfit for curative therapy and older than 65 showed a steady increase which can be attributed to the introduction of new therapeutic alternatives. Orv Hetil. 2023; 164(45): 1787-1794.

Cannabinoid receptor type 1 (CB1R) inhibits hypothalamic leptin signaling via ß-arrestin1 in complex with TC-PTP and STAT3.

Molecular interactions between anorexigenic leptin and orexigenic endocannabinoids, although of great metabolic significance, are not well understood. We report here that hypothalamic STAT3 signaling in mice, initiated by physiological elevations of leptin, is diminished by agonists of the cannabinoid receptor 1 (CB1R). Measurement of STAT3 activation by semi-automated confocal microscopy in cultured neurons revealed that this CB1R-mediated inhibition requires both T cell protein tyrosine phosphatase (TC-PTP) and ß-arrestin1 but is independent of changes in cAMP. Moreover, ß-arrestin1 translocates to the nucleus upon CB1R activation and binds both STAT3 and TC-PTP. Consistently, CB1R activation failed to suppress leptin signaling in ß-arrestin1 knockout mice in vivo, and in neural cells deficient in CB1R, ß-arrestin1 or TC-PTP. Altogether, CB1R activation engages ß-arrestin1 to coordinate the TC-PTP-mediated inhibition of the leptin-evoked neuronal STAT3 response. This mechanism may restrict the anorexigenic effects of leptin when hypothalamic endocannabinoid levels rise, as during fasting or in diet-induced obesity.

Soluble B-cell maturation antigen as a monitoring marker for multiple myeloma.

Objective: Response to treatment in multiple myeloma (MM) is routinely measured by serum and urine M-protein and free light chain (FLC), as described by the International Myeloma Working Group (IMWG) consensus statement. A non-negligible subgroup of patients however present without measurable biomarkers, others become oligo or non-secretory during recurrent relapses. The aim of our research was to evaluate soluble B-cell maturation antigen (sBCMA) as a monitoring marker measured concurrent with the standard monitoring in MM patients at diagnosis, at relapse and during follow up, in order to establish its potential usefulness in oligo and non-secretory disease. Method: sBCMA levels were measured in 149 patients treated for plasma cell dyscrasia (3 monoclonal gammopathy of unknown significance, 5 smoldering myeloma, 7 plasmacytoma, 8 AL amyloidosis and 126 MM) and 16 control subjects using a commercial ELISA kit. In 43 newly diagnosed patients sBCMA levels were measured at multiple timepoints during treatment, and compared to conventional IMWG response and progression free survival (PFS). Results: sBCMA levels among control subjects were significantly lower than among newly diagnosed or relapsed MM patients [20.8 (14.7-38.7) ng/mL vs. 676 (89.5-1,650) and 264 (20.7-1,603) ng/mL, respectively]. Significant correlations were found between sBCMA and the degree of bone marrow plasma cell infiltration. Out of the 37 newly diagnosed patients who have reached partial response or better per IMWG criteria, 33 (89%) have had at least a 50% drop in sBCMA level by therapy week 4. Cohorts made similarly to IMWG response criteria-achieving a 50% or 90% drop in sBCMA levels compared to level at diagnosis-had statistically significant differences in PFS. Conclusion: Our results confirmed that sBCMA levels are prognostic at important decision points in myeloma, and the percentage of BCMA change is predictive for PFS. This highlights the great potential use of sBCMA in oligo- and non-secretory myeloma.

An Unexpected Enzyme in Vascular Smooth Muscle Cells: Angiotensin II Upregulates Cholesterol-25-Hydroxylase Gene Expression.

Angiotensin II (AngII) is a vasoactive peptide hormone, which, under pathological conditions, contributes to the development of cardiovascular diseases. Oxysterols, including 25-hydroxycholesterol (25-HC), the product of cholesterol-25-hydroxylase (CH25H), also have detrimental effects on vascular health by affecting vascular smooth muscle cells (VSMCs). We investigated AngII-induced gene expression changes in VSMCs to explore whether AngII stimulus and 25-HC production have a connection in the vasculature. RNA-sequencing revealed that Ch25h is significantly upregulated in response to AngII stimulus. The Ch25h mRNA levels were elevated robustly (~50-fold) 1 h after AngII (100 nM) stimulation compared to baseline levels. Using inhibitors, we specified that the AngII-induced Ch25h upregulation is type 1 angiotensin II receptor- and Gq/11 activity-dependent. Furthermore, p38 MAPK has a crucial role in the upregulation of Ch25h. We performed LC-MS/MS to identify 25-HC in the supernatant of AngII-stimulated VSMCs. In the supernatants, 25-HC concentration peaked 4 h after AngII stimulation. Our findings provide insight into the pathways mediating AngII-induced Ch25h upregulation. Our study elucidates a connection between AngII stimulus and 25-HC production in primary rat VSMCs. These results potentially lead to the identification and understanding of new mechanisms in the pathogenesis of vascular impairments.

Cardiac Amyloidosis with Normal Wall Thickness: Prevalence, Clinical Characteristics and Outcome in a Retrospective Analysis.

Background: Cardiac amyloidosis (CA) is a rare, progressive, infiltrative cardiac disease. Light chain (AL) and transthyretin (ATTR) amyloidosis are in the background in almost all cases. New, easily available diagnostic tools and recently introduced novel therapies for both types of CA put this disease into the field of interest. Increased left ventricular wall thickness (IWT) detected by echocardiography is generally thought to be a necessary part of the diagnosis. We aimed to determine the proportion of CA patients without IWT, and to define the clinical characteristics of this cohort. Methods: In an academic tertiary center for CA, we identified patients diagnosed and treated for CA between January 2009 and February 2022. In a retrospective analysis we defined the proportion of patients with (≥12 mm) and without (<12 mm) IWT, and described their clinical features. Results: We identified 98 patients suitable for the analysis. In total, 70 had AL and 27 ATTR CA; 89 patients had CA with IWT and 9 patients (9%) had CA without IWT. All non-IWT patients had AL type CA. Both group of patients had clinically significant disease, which is supported by the relevant elevation in cardiac biomarker levels. There was no difference between the outcome of the two groups. Conclusion: Patients without IWT form a relevant subgroup among those with CA. Our results suggest that diagnostic algorithms and criteria should take these individuals into consideration, and, therefore, give them access to effective treatments.

Functional Rescue of a Nephrogenic Diabetes Insipidus Causing Mutation in the V2 Vasopressin Receptor by Specific Antagonist and Agonist Pharmacochaperones.

The urine concentrating function of the kidney is essential to maintain the water homeostasis of the human body. It is mainly regulated by the arginine-vasopressin (AVP), which targets the type 2 vasopressin receptor (V2R) in the kidney. The inability of V2R to respond to AVP stimulation leads to decreased urine concentration and congenital nephrogenic diabetes insipidus (NDI). NDI is characterized by polyuria, polydipsia, and hyposthenuria. In this study, we identified a point mutation (S127F) in the AVPR2 gene of an NDI patient, and we characterized the impaired function of the V2R mutant in HEK293 cells. Based on our data, the S127F-V2R mutant is almost exclusively located intracellularly in the endoplasmic reticulum (ER), and very few receptors were detected at the cell surface, where the receptor can bind to AVP. The overexpressed S127F-V2R mutant receptor has negligible cAMP generation capability compared to the wild-type receptor in response to AVP stimulation. Since certain misfolded mutant proteins, that are retained in the ER, can be rescued by pharmacological chaperones, we examined the potential rescue effects of two pharmacochaperones on the S127F-V2R. We found that pretreatment with both tolvaptan (an established V2R inverse agonist) and MCF14 compound (a cell-permeable high-affinity agonist for the V2R) were capable of partially restoring the cAMP generating function of the receptor in response to vasopressin stimulation. According to our data, both cell permeant agonists and antagonists can function as pharmacochaperones, and serve as the starting compounds to develop medicines for patients carrying the S127F mutation.

Characterization of Type 1 Angiotensin II Receptor Activation Induced Dual-Specificity MAPK Phosphatase Gene Expression Changes in Rat Vascular Smooth Muscle Cells.

Activation of the type I angiotensin receptor (AT1-R) in vascular smooth muscle cells (VSMCs) plays a crucial role in the regulation of blood pressure; however, it is also responsible for the development of pathological conditions such as vascular remodeling, hypertension and atherosclerosis. Stimulation of the VSMC by angiotensin II (AngII) promotes a broad variety of biological effects, including gene expression changes. In this paper, we have taken an integrated approach in which an analysis of AngII-induced gene expression changes has been combined with the use of small-molecule inhibitors and lentiviral-based gene silencing, to characterize the mechanism of signal transduction in response to AngII stimulation in primary rat VSMCs. We carried out Affymetrix GeneChip experiments to analyze the effects of AngII stimulation on gene expression; several genes, including DUSP5, DUSP6, and DUSP10, were identified as upregulated genes in response to stimulation. Since various dual-specificity MAPK phosphatase (DUSP) enzymes are important in the regulation of mitogen-activated protein kinase (MAPK) signaling pathways, these genes have been selected for further analysis. We investigated the kinetics of gene-expression changes and the possible signal transduction processes that lead to altered expression changes after AngII stimulation. Our data shows that the upregulated genes can be stimulated through multiple and synergistic signal transduction pathways. We have also found in our gene-silencing experiments that epidermal growth factor receptor (EGFR) transactivation is not critical in the AngII-induced expression changes of the investigated genes. Our data can help us understand the details of AngII-induced long-term effects and the pathophysiology of AT1-R. Moreover, it can help to develop potential interventions for those symptoms that are induced by the over-functioning of this receptor, such as vascular remodeling, cardiac hypertrophy or atherosclerosis.

Optimization of the Heterologous Expression of the Cannabinoid Type-1 (CB1) Receptor.

The G protein-coupled type 1 cannabinoid receptor (CB1R) mediates virtually all classic cannabinoid effects, and both its agonists and antagonists hold major therapeutic potential. Heterologous expression of receptors is vital for pharmacological research, however, overexpression of these proteins may fundamentally alter their localization pattern, change the signalling partner preference and may also spark artificial clustering. Additionally, recombinant CB1Rs are prone to intense proteasomal degradation, which may necessitate substantial modifications, such as N-terminal truncation or signal sequence insertion, for acceptable cell surface expression. We report here that tuning down the expression intensity of the full-length CB1R reduces proteasomal degradation and offers receptor levels that are comparable to those of endogenous CB1 receptors. As opposed to high-efficiency expression with conventional promoters, weak promoter-driven CB1R expression provides ERK 1/2 and p38 MAPK signalling that closely resemble the activity of endogenous CB1Rs. Moreover, weakly expressed CB1R variants exhibit plasma membrane localization, preserve canonical Gi-signalling but prevent CB1R-Gs coupling observed with high-expression variants. Based on these findings, we propose that lowering the expression level of G protein-coupled receptors should always be considered in heterologous expression systems in order to reduce the pressure on the proteasomal machinery and to avoid potential signalling artefacts.

PharmacoSTORM nanoscale pharmacology reveals cariprazine binding on Islands of Calleja granule cells.

Immunolabeling and autoradiography have traditionally been applied as the methods-of-choice to visualize and collect molecular information about physiological and pathological processes. Here, we introduce PharmacoSTORM super-resolution imaging that combines the complementary advantages of these approaches and enables cell-type- and compartment-specific nanoscale molecular measurements. We exploited rational chemical design for fluorophore-tagged high-affinity receptor ligands and an enzyme inhibitor; and demonstrated broad PharmacoSTORM applicability for three protein classes and for cariprazine, a clinically approved antipsychotic and antidepressant drug. Because the neurobiological substrate of cariprazine has remained elusive, we took advantage of PharmacoSTORM to provide in vivo evidence that cariprazine predominantly binds to D3 dopamine receptors on Islands of Calleja granule cell axons but avoids dopaminergic terminals. These findings show that PharmacoSTORM helps to quantify drug-target interaction sites at the nanoscale level in a cell-type- and subcellular context-dependent manner and within complex tissue preparations. Moreover, the results highlight the underappreciated neuropsychiatric significance of the Islands of Calleja in the ventral forebrain.

Biased Coupling to ß-Arrestin of Two Common Variants of the CB2 Cannabinoid Receptor.

ß-arrestins are partners of the G protein-coupled receptors (GPCRs), regulating their intracellular trafficking and signaling. Development of biased GPCR agonists, selectively targeting either G protein or ß-arrestin pathways, are in the focus of interest due to their therapeutic potential in different pathological conditions. The CB2 cannabinoid receptor (CB2R) is a GPCR involved in various functions in the periphery and the central nervous system. Two common occurring variants of CB2R, harboring Q63R or L133I missense mutations, have been implicated in the development of a diverse set of disorders. To evaluate the effect of these mutations, we characterized the binding profile of these mutant CB2 receptors to G proteins and ß-arrestin2. Although their ability to inhibit cAMP signaling was similar, the Q63R mutant had increased, whereas the L133I mutant receptor had decreased ß-arrestin2 binding. In line with these observations, the variants also had altered intracellular trafficking. Our results show that two common variants of the CB2 receptor have biased signaling properties, which may contribute to the pathogenesis of the associated disorders and may offer CB2R as a target for further development of biased receptor activation strategies.

A general method for quantifying ligand binding to unmodified receptors using Gaussia luciferase.

Reliable measurement of ligand binding to cell surface receptors is of outstanding biological and pharmacological importance. Resonance energy transfer-based assays are powerful approaches to achieve this goal, but the currently available methods are hindered by the necessity of receptor tagging, which can potentially alter ligand binding properties. Therefore, we developed a tag-free system to measure ligand‒receptor interactions in live cells using the Gaussia luciferase (GLuc) as a bioluminescence resonance energy transfer donor. GLuc is as small as the commonly applied Nanoluciferase but has enhanced brightness, and its proper substrate is the frequently used coelenterazine. In our assay, bystander bioluminescence resonance energy transfer is detected between a GLuc-based extracellular surface biosensor and fluorescent ligands bound to their unmodified receptors. The broad spectrum of applications includes equilibrium and kinetic ligand binding measurements for both labeled and competitive unlabeled ligands, and the assay can be utilized for different classes of plasma membrane receptors. Furthermore, the assay is suitable for high-throughput screening, as evidenced by the identification of novel α1 adrenergic receptor ligands. Our data demonstrate that GLuc-based biosensors provide a simple, sensitive, and cost-efficient platform for drug characterization and development.