Modulation Of Proteins Research Articles

Quantitative proteomic analysis of circulating exosomes reveals the mechanism by which Triptolide protects against collagen-induced arthritis.

Triptolide (TP), a natural product derived from the herbal medicine Tripterygium wilfordii, exhibits potent immunosuppressive activity. However, the mechanisms underlying its effects in rheumatoid arthritisremain incompletely understood. Collagen-induced arthritis (CIA) model was induced in Sprague-Dawley rats by immunization with bovine type II collagen, and TP was administrated as treatment. The therapeutic effect of TP was evaluated based on paw swelling, histopathology, and serum levels of inflammatory factors. Exosomes isolated from rat serum were characterized by transmission electron microscopy, dynamic light scattering, and western blotanalysis. Proteomic profiling of exosomes was analyzed by direct DIA quantitative proteomics analysis. Gene ontology and the Kyoto Encyclopedia of Genes and Genomes databases were employed for enrichment analysis related to molecular function, biological processes, and signaling pathways. Western blot analysis was used to analyze differentially expressed proteins. TP treatment ameliorated arthritic phenotypes in CIA rats as evidenced by reduced arthritis score, paw swelling, pathological injury severity scores, and serum levels of inflammatory cytokines. The proteomic analysis revealed that TP treatment significantly inhibited complement and coagulation cascades, interleukin-17 signaling pathway, and cholesterol metabolism, which were reactivated in CIA rats. Importantly, lipocalin 2 (LCN2) and myeloperoxidase (MPO) levels were markedly upregulated in the CIA group but suppressed upon TP administration. Furthermore, in synovial tissues, LCN2 and MPO expression levels were also elevated in the CIA group but decreased following TP treatment. Our findings demonstrate that TP alleviates CIA, possibly through modulation of exosomal LCN2 and MPO proteins.

Shenqi Fuzheng injection facilitates skeletal muscle mitophagy mediated by the ubiquitination of HIF-1α to ameliorate cancer-associated fatigue.

Cancer-related fatigue (CRF) significantly impacts the quality of life of cancer patients. This study investigates the therapeutic potential of Shenqi Fuzheng injection (SFI) in managing CRF, focusing on its mechanistic action in skeletal muscle. We utilized a CRF mouse model to examine the effects of SFI on physical endurance, monitoring activity levels, swimming times and rest periods. Proteomic analysis of the gastrocnemius muscle was performed using isobaric tags and liquid chromatography-tandem mass spectrometry to map the muscle proteome changes post-SFI treatment. Mitochondrial function in skeletal muscle was assessed via ATP bioluminescence assay. Furthermore, the regulatory role of the hypoxia inducible factor 1 subunit alpha (HIF-1α) signalling pathway in mediating SFI's effects was explored through western blotting. In CRF-induced C2C12 myoblasts, we evaluated cell viability (CCK-8 assay), apoptosis (flow cytometry) and mitophagy (electron microscopy). The study also employed pulldown, luciferase and chromatin immunoprecipitation assays to elucidate the molecular mechanisms underlying SFI's action, particularly focusing on the transcriptional regulation of PINK1 through HIF-1α binding at the PINK1 promoter region. Our findings reveal that SFI enhances physical mobility, reduces fatigue symptoms and exerts protective effects on skeletal muscles by mitigating mitochondrial damage and augmenting antioxidative responses. SFI promotes cell viability and induces mitophagy while decreasing apoptosis, primarily through the modulation of HIF-1α, PINK1 and p62 proteins. These results underscore SFI's efficacy in enhancing mitochondrial autophagy, thereby offering a promising approach for ameliorating CRF. The study not only provides insight into SFI's potential therapeutic mechanisms but also establishes a foundation for further exploration of SFI interventions in CRF management.

P025 The haves and the have nots: characterising the CFTR protein modulator ineligible cohort in a large paediatric cystic fibrosis (CF) centre

P025 The haves and the have nots: characterising the CFTR protein modulator ineligible cohort in a large paediatric cystic fibrosis (CF) centre

Evaluating the correlation between expression levels of carboxyl terminal modulator protein (CTMP) and the efficacy of trastuzumab in Syrian patients with HER2+ metastatic breast cancer.

Evaluating the correlation between expression levels of carboxyl terminal modulator protein (CTMP) and the efficacy of trastuzumab in Syrian patients with HER2+ metastatic breast cancer.

Blockade of mGluR5 in nucleus accumbens modulates calcium sensor proteins, facilitates extinction, and attenuates reinstated morphine place preference in rats

Numerous findings confirm that the metabotropic glutamate receptors (mGluRs) are involved in the conditioned place preference (CPP) induced by morphine. Here we focused on the role of mGluR5 in the nucleus accumbens (NAc) as a main site of glutamate action on the rewarding effects of morphine. Firstly, we investigated the effects of intra-NAc administrating mGluR5 antagonist 3-((2-Methyl-1,3-thiazol-4-yl) ethynyl) pyridine hydrochloride (MTEP; 1, 3, and 10 μg/μl saline) on the extinction and the reinstatement phase of morphine CPP. Moreover, to determine the downstream signaling cascades of mGluR5 in morphine CPP, the protein levels of stromal interaction molecules (STIM1 and 2) in the NAc and hippocampus (HPC) were measured by western blotting. The behavioral data indicated that the mGluR5 blockade by MTEP at the high doses of 3 and 10 μg facilitated the extinction of morphine-induced CPP and attenuated the reinstatement to morphine in extinguished rats. Molecular results showed that the morphine led to increased levels of STIM proteins in the HPC and increased the level of STIM1 without affecting STIM2 in the NAc. Furthermore, intra-NAc microinjection of MTEP (10 μg) in the reinstatement phase decreased STIM1 in the NAc and HPC and reduced the STIM2 in the HPC. Collectively, our data show that morphine could facilitate brain reward function in part by increasing glutamate-mediated transmission through activation of mGluR5 and modulation of STIM proteins. Therefore, these results highlight the therapeutic potential of mGluR5 antagonists in morphine use disorder.

Akkermansia muciniphila postbiotic administration mitigates choline-induced plasma Trimethylamine-N-Oxide production in mice

BackgroundTrimethylamine-N-Oxide (TMAO) is believed to be linked to increased likelihood of cardiovascular disease. While probiotics have shown limited effectiveness in reducing TMAO levels, the potential of postbiotics remains underexplored. This study aimed to evaluate the impact of Akkermansia muciniphila (A. muciniphila) postbiotic administration on choline-induced TMAO production in mice by modifying the gut microbiota.MethodsFemale C57BL/6J mice were divided into six groups, including a control group, high-choline diet group, live A. muciniphila probiotic group, pasteurized A. muciniphila postbiotic group, sodium butyrate group, and sodium propionate group. Various measurements and analyses were conducted, including TMAO and TMA levels in serum, urine, and cecal contents, as well as the expression of FXR and FMO3 in liver tissues. Additionally, metabolic parameters, body weight, serum lipid profile, hepatic protein expression (FMO3, FXR, CutC, and CutD), and gut microbiota composition were assessed.ResultsAdministration of A. muciniphila postbiotic significantly reduced choline-induced plasma TMAO levels in mice. Furthermore, improvements in serum lipid profiles and liver enzyme levels suggested potential enhancements in lipid metabolism and liver function. The study also observed modulation of specific proteins related to TMAO production and metabolism, including CutC and CutD.ConclusionThe findings highlight the potential of A. muciniphila postbiotics as a dietary strategy for mitigating cardiovascular disease risk by modulating the gut-TMAO axis. Postbiotics, particularly A. muciniphila, offer advantages over probiotics and warrant further investigation for their therapeutic applications in gastrointestinal and metabolic disorders.Graphical

Proteomic Analysis of Milk Fat Globule Membrane Protein Modulation of Differently Expressed Proteins in Lactobacillus plantarum under Bile Salt Stress.

Tolerance to bile stress is a crucial property for lactic acid bacteria (LAB) to survive in the gastrointestinal tract and exert their beneficial effects. Whey powder enriched with milk fat globule membrane proteins (M-WPI) as a functional component is protective for strains under stress conditions. The current study investigated the key mechanisms of action involved in Lactobacillus plantarum (L. plantarum) CGMCC 23701 survival in the presence of bile and the protective mechanism of M-WPI. According to proteomic analysis (proteomics), there could be several reasons for the greater protective effect of M-WPI. These include promoting the synthesis of fatty acids and peptidoglycans to repair the structure of the cell surface, regulating the metabolism of carbohydrates and amino acids to release energy and produce a range of precursors, enabling the expression of the repair system to repair damaged DNA, and promoting the expression of proteins associated with the multidrug efflux pump, which facilitates the exocytosis of intracellular bile salts. This study helps us to better understand the changes in proteome of L. plantarum CGMCC 23701 under bile salt stress and M-WPI protection, which will provide a new method for the protection and development of functional LAB.

Diving into progress: a review on current therapeutic advancements in spinal muscular atrophy

Spinal muscular atrophy (SMA) is an uncommon disorder associated with genes characterized by the gradual weakening and deterioration of muscles, often leading to substantial disability and premature mortality. Over the past decade, remarkable strides have been made in the field of SMA therapeutics, revolutionizing the landscape of patient care. One pivotal advancement is the development of gene-targeted therapies, such as nusinersen, onasemnogene abeparvovec and risdiplam which have demonstrated unprecedented efficacy in slowing disease progression. These therapies aim to address the root cause of SMA by targeting the survival motor neuron (SMN) gene, effectively restoring deficient SMN protein levels. The advent of these innovative approaches has transformed the prognosis for many SMA patients, offering a glimmer of hope where there was once limited therapeutic recourse. Furthermore, the emergence of small molecule compounds and RNA-targeting strategies has expanded the therapeutic arsenal against SMA. These novel interventions exhibit diverse mechanisms of action, including SMN protein stabilization and modulation of RNA splicing, showcasing the multifaceted nature of SMA treatment research. Collective efforts of pharmaceutical industries, research centers, and patient advocacy groups have played an important role in expediting the translation of scientific discoveries into visible clinical benefits. This review not only highlights the remarkable progress achieved in SMA therapeutics but also generates the ray of hope for the ongoing efforts required to enhance accessibility, optimize treatment strategies, rehabilitation (care and therapies) and ultimately pave the way for an improved quality of life for individuals affected by SMA.

#1521 EZH2 promotes cyst growth in autosomal dominant polycystic kidney disease

Abstract Background and Aims Autosomal dominant polycystic kidney disease (ADPKD) is the leading hereditary kidney disease worldwide. Epigenetic modulations of genes and proteins play important roles in ADPKD pathogenesis. In this study, the role of enhancer of zeste homolog 2 (EZH2), a histone lysine methyltransferase, was investigated in ADPKD. Method To elucidate the role of EZH2 in ADPKD pathogenesis, we employed inducible knockout models, specifically targeting Pkd1 alone (Pkd1fl/fl) or both Pkd1 and EZH2 (Pkd1fl/fl: Ezh2fl/fl) in mouse models. Molecular analyses included assessing EZH2 expression levels and H3K27 trimethylation in Pkd1 knockout cells, kidney tissues from Pkd1 knockout mice, and samples from ADPKD patients. Functional investigations involved the use of EZH2-specific inhibitors, GSK126 and EPZ-6438, to inhibit EZH2 activity. Additionally, Ezh2 knockdown was employed to assess its impact on cystogenesis in MDCK cells. The embryonic kidney cyst model was utilized to evaluate the effects of GSK126 and EPZ-6438 on cyst growth. Results We found that EZH2 expression and the trimethylation of lysine 27 on histone H3 (H3K27) were upregulated in Pkd1 knockout cells and kidney tissues of Pkd1 knockout mice and ADPKD patients. Using EZH2-specific inhibitors GSK126/EPZ-6438 and knockdown of Ezh2 both suppressed cystogenesis in MDCK cells. GSK126 and EPZ-6438 delayed cyst growth in the embryonic kidney cyst model. Double knockout of Pkd1 and Ezh2 significantly decreased the kidney volume, cyst indexes, H3K27 methylation level, and the proliferation of renal cystic epithelial cells compared with Pkd1 knockout mice. Moreover, GSK126 delayed cyst growth and protected renal function in both early- and late-onset Pkd1 conditional knockout mice. EZH2 promoted the proliferation of renal cystic epithelial cells by activating STAT3 through H3K27 methylation. Conclusion Inhibiting EZH2 emerged as a promising strategy to impede cyst growth and attenuate disease progression across various PKD models. These findings establish a molecular foundation for the potential use of EZH2-specific inhibitors in delaying ADPKD cyst growth in the future.

Hydrophobic Mismatch in the Thylakoid Membrane Regulates Photosynthetic Light Harvesting.

The ability to harvest light effectively in a changing environment is necessary to ensure efficient photosynthesis and crop growth. One mechanism, known as qE, protects photosystem II (PSII) and regulates electron transfer through the harmless dissipation of excess absorbed photons as heat. This process involves reversible clustering of the major light-harvesting complexes of PSII (LHCII) in the thylakoid membrane and relies upon the ΔpH gradient and the allosteric modulator protein PsbS. To date, the exact role of PsbS in the qE mechanism has remained elusive. Here, we show that PsbS induces hydrophobic mismatch in the thylakoid membrane through dynamic rearrangement of lipids around LHCII leading to observed membrane thinning. We found that upon illumination, the thylakoid membrane reversibly shrinks from around 4.3 to 3.2 nm, without PsbS, this response is eliminated. Furthermore, we show that the lipid digalactosyldiacylglycerol (DGDG) is repelled from the LHCII-PsbS complex due to an increase in both the pKa of lumenal residues and in the dipole moment of LHCII, which allows for further conformational change and clustering in the membrane. Our results suggest a mechanistic role for PsbS as a facilitator of a hydrophobic mismatch-mediated phase transition between LHCII-PsbS and its environment. This could act as the driving force to sort LHCII into photoprotective nanodomains in the thylakoid membrane. This work shows an example of the key role of the hydrophobic mismatch process in regulating membrane protein function in plants.

Phase separation-competent FBL promotes early pre-rRNA processing and translation in acute myeloid leukaemia.

RNA-binding proteins (RBPs) are pivotal in acute myeloid leukaemia (AML), a lethal disease. Although specific phase separation-competent RBPs are recognized in AML, the effect of their condensate formation on AML leukaemogenesis, and the therapeutic potential of inhibition of phase separation are underexplored. In our in vivo CRISPR RBP screen, fibrillarin (FBL) emerges as a crucial nucleolar protein that regulates AML cell survival, primarily through its phase separation domains rather than methyltransferase or acetylation domains. These phase separation domains, with specific features, coordinately drive nucleoli formation and early processing of pre-rRNA (including efflux, cleavage and methylation), eventually enhancing the translation of oncogenes such as MYC. Targeting the phase separation capability of FBL with CGX-635 leads to elimination of AML cells, suggesting an additional mechanism of action for CGX-635 that complements its established therapeutic effects. We highlight the potential of PS modulation of critical proteins as a possible therapeutic strategy for AML.

Suanzaoren decoction exerts its antidepressant effect via the CaMK signaling pathway.

Calmodulin-dependent protein kinases (CaMKs) are widely regarded as "memory molecules" due to their role in controlling numerous neuronal functions in the brain, and the CaMK signaling pathway plays a crucial role in controlling synaptic plasticity. Suanzaoren decoction (SZRD) can improve depression-like behavior and thus has potential benefits in the clinical treatment of depression; however, its mechanism of action is not fully understood. In this study, we found that key proteins in the CaMK signaling pathway were regulated by the decoction used to treat depression. The purpose of this research was to ascertain if the SZRD's therapeutic efficacy in the treatment of depression is associated with the modulation of key proteins in the CaMK signaling pathway. A rat model of depression was created by exposing the animals to chronic, unexpected, mild stress. Model rats were given intragastric administration of SZRD or fluoxetine every morning once a day. Protein and mRNA relative expression levels of CaM, CaMK I, and CaMK IV in the hippocampus were measured by Western blot, quantitative polymerase chain reaction, and immunohistochemistry in the hippocampus. Our findings demonstrated that SZRD significantly improved the mood of depressed rats. This indicates that SZRD, by modulating the CaMK signaling system, may alleviate depressive symptoms and lessen work and life-related pressures.

Metformin induction of heat shock factor 1 activation and the mitochondrial unfolded protein response alleviate cardiac remodeling in spontaneously hypertensive rats.

Heart failure and cardiac remodeling are both characterized by mitochondrial dysfunction. Healthy mitochondria are required for adequate contractile activity and appropriate regulation of cell survival. In the mammalian heart, enhancement of the mitochondrial unfolded protein response (UPRmt) is cardioprotective under pressure overload conditions. We explored the UPRmt and the underlying regulatory mechanism in terms of hypertension-induced cardiac remodeling and the cardioprotective effect of metformin. Male spontaneously hypertensive rats and angiotensin II-treated neonatal rat cardiomyocytes were used to induce cardiac hypertrophy. The results showed that hypertension induced the formation of aberrant mitochondria, characterized by a reduced mtDNA/nDNA ratio and swelling, as well as lower levels of mitochondrial complexes I to V and inhibition of the expression of one protein subunit of each of complexes I to IV. Such changes eventually enlarged cardiomyocytes and increased cardiac fibrosis. Metformin treatment increased the mtDNA/nDNA ratio and regulated the UPRmt, as indicated by increased expression of activating transcription factor 5, Lon protease 1, and heat shock protein 60, and decreased expression of C/EBP homologous protein. Thus, metformin improved mitochondrial ultrastructure and function in spontaneously hypertensive rats. Invitro analyses revealed that metformin reduced the high levels of angiotensin II-induced mitochondrial reactive oxygen species in such animals and stimulated nuclear translocation of heat shock factor 1 (HSF1). Moreover, HSF1 small-interfering RNA reduced the metformin-mediated improvements in mitochondrial morphology and the UPRmt by suppressing hypertrophic signals and cardiomyocyte apoptosis. These results suggest that HSF1/UPRmt signaling contributes to the beneficial effects of metformin. Metformin-mediated targeting of mitochondrial protein homeostasis and modulation of HSF1 levels have potential therapeutic implications in terms of cardiac remodeling.

KiSS-1 Modulation by Epigenetic Agents Improves the Cisplatin Sensitivity of Lung Cancer Cells.

Epigenetic alterations my play a role in the aggressive behavior of Non-Small Cell Lung Cancer (NSCLC). Treatment with the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA, vorinostat) has been reported to interfere with the proliferative and invasive potential of NSCLC cells. In addition, the DNA methyltransferase inhibitor azacytidine (AZA, vidaza) can modulate the levels of the metastasis suppressor KiSS-1. Thus, since cisplatin is still clinically available for NSCLC therapy, the aim of this study was to evaluate drug combinations between cisplatin and SAHA as well as AZA using cisplatin-sensitive H460 and -resistant H460/Pt NSCLC cells in relation to KiSS-1 modulation. An analysis of drug interaction according to the Combination-Index values indicated a more marked synergistic effect when the exposure to SAHA or AZA preceded cisplatin treatment with respect to a simultaneous schedule. A modulation of proteins involved in apoptosis (p53, Bax) was found in both sensitive and resistant cells, and compared to the treatment with epigenetic agents alone, the combination of cisplatin and SAHA or AZA increased apoptosis induction. The epigenetic treatments, both as single agents and in combination, increased the release of KiSS-1. Finally, the exposure of cisplatin-sensitive and -resistant cells to the kisspeptin KP10 enhanced cisplatin induced cell death. The efficacy of the combination of SAHA and cisplatin was tested in vivo after subcutaneous inoculum of parental and resistant cells in immunodeficient mice. A significant tumor volume inhibition was found when mice bearing advanced tumors were treated with the combination of SAHA and cisplatin according to the best schedule identified in cellular studies. These results, together with the available literature, support that epigenetic drugs are amenable for the combination treatment of NSCLC, including patients bearing cisplatin-resistant tumors.

Linagliptin ameliorates tacrolimus-induced renal injury: role of Nrf2/HO-1 and HIF-1α/CTGF/PAI-1

BackgroundTacrolimus (TAC) is a frequently used immunosuppressive medication in organ transplantation. However, its nephrotoxic impact limits its long-term usage. This study aims to investigate the effect of linagliptin (Lina) on TAC-induced renal injury and its underlying mechanisms.Methods and resultsThirty-two Sprague Dawley rats were treated with TAC (1.5 mg/kg/day, subcutaneously) and/or Lina (5 mg/kg/day, orally) for 4 weeks. Histological examination was conducted, and serum and urinary biomarkers were measured to assess kidney function and integrity. Furthermore, ELISA, Western blot analysis and immunohistochemical assay were employed to determine signaling molecules of oxidative stress, profibrogenic, hypoxic, and apoptotic proteins. Tacrolimus caused renal dysfunction and histological deterioration evidenced by increased serum creatinine, blood urea nitrogen (BUN), urinary cystatin C, and decreased serum albumin as well as elevated tubular injury and interstitial fibrosis scores. Additionally, TAC significantly increased the expression of collagen type-1, alpha-smooth muscle actin (α-SMA), plasminogen activator inhibitor-1 (PAI-1), and transforming growth factor-beta1 (TGF-β1) renal content. Moreover, TAC decreased the expression of nuclear factor erythroid-2-related factor2 (Nrf2), heme oxygenase 1 (HO-1), and mitochondrial superoxide dismutase (SOD2). In addition, TAC increased protein expression of hypoxia-inducible factor1-alpha (HIF-1α), connective tissue growth factor (CTGF), inducible nitric oxide synthase (iNOS), 8-hydroxy-2-deoxyguanosine (8-OHdG), as well as nitric oxide (NO), 4-hydroxynonenal, caspase-3 and Bax renal contents. Furthermore, TAC decreased Bcl-2 renal contents. The Lina administration markedly attenuated these alterations.ConclusionLina ameliorated TAC-induced kidney injury through modulation of oxidative stress, hypoxia, and apoptosis related proteins.

Crystal structure of the long Rib domain of the LPXTG-anchored surface protein from Limosilactobacillus reuteri.

The Rib domain, which is often found as tandem-repeat structural modules in surface proteins of Gram-positive bacteria, plays important roles in mediating interactions of bacteria with their environments and hosts. A comprehensive structural analysis of various Rib domains is essential to fully understand their impact on the structure and functionality of these bacterial adhesins. To date, structural information has been limited for this expansive group of domains. In this study, the high-resolution crystal structure of the second member of the long Rib domain, a unique subclass within the Rib-domain family, derived from Limosilactobacillus reuteri is presented. The data not only demonstrate a highly conserved structure within the long Rib domain, but also highlight an evolutionary convergence in structural architecture with other modular domains found in cell-adhesion molecules.

Management of dyslipidemia in coronary artery disease: the present and the future.

Coronary artery disease (CAD) remains a leading cause of global morbidity and mortality, necessitating continuous refinement in the management of dyslipidemia, one of its major risk factors, to mitigate cardiovascular risks. Previous studies have proven the critical role of immediate and robust low-density lipoprotein cholesterol (LDL-C) reduction in the aftermath of acute coronary syndrome (ACS). Emphasizing the evidence supporting this approach, we delve into the impact of early intervention on cardiovascular outcomes and propose optimal strategies for achieving rapid LDL-C lowering, while also providing the rationale for early proprotein convertase subtilisin/kexin 9 inhibitor use after an ACS. Given the importance of the residual lipidemic risk, we present an overview of emerging therapeutic avenues poised to reshape dyslipidemia management, such as bempedoic acid, lipoprotein(a) inhibition, ApoC3 modulation, and angiopoietin-like protein 3 targeting. This comprehensive review amalgamates current evidence with future prospects, offering a holistic perspective on the management of dyslipidemia in CAD. By exploring both the urgency for immediate post-ACS LDL-C reduction and the exciting advancements on the horizon, this article provides a roadmap for clinicians navigating the intricate landscape of lipid-lowering therapies in CAD.

Large-scale chemoproteomics expedites ligand discovery and predicts ligand behavior in cells.

Chemical modulation of proteins enables a mechanistic understanding of biology and represents the foundation of most therapeutics. However, despite decades of research, 80% of the human proteome lacks functional ligands. Chemical proteomics has advanced fragment-based ligand discovery toward cellular systems, but throughput limitations have stymied the scalable identification of fragment-protein interactions. We report proteome-wide maps of protein-binding propensity for 407 structurally diverse small-molecule fragments. We verified that identified interactions can be advanced to active chemical probes of E3 ubiquitin ligases, transporters, and kinases. Integrating machine learning binary classifiers further enabled interpretable predictions of fragment behavior in cells. The resulting resource of fragment-protein interactions and predictive models will help to elucidate principles of molecular recognition and expedite ligand discovery efforts for hitherto undrugged proteins.

Membrane Heteroreceptor Complexes as Second-Order Protein Modulators: A Novel Integrative Mechanism through Allosteric Receptor-Receptor Interactions.

Bioluminescence and fluorescence resonance energy transfer (BRET and FRET) together with the proximity ligation method revealed the existence of G-protein-coupled receptors, Ionotropic and Receptor tyrosine kinase heterocomplexes, e.g., A2AR-D2R, GABAA-D5R, and FGFR1-5-HT1AR heterocomplexes. Molecular integration takes place through allosteric receptor-receptor interactions in heteroreceptor complexes of synaptic and extra-synaptic regions. It involves the modulation of receptor protomer recognition, signaling and trafficking, as well as the modulation of behavioral responses. Allosteric receptor-receptor interactions in hetero-complexes give rise to concepts like meta-modulation and protein modulation. The introduction of receptor-receptor interactions was the origin of the concept of meta-modulation provided by Katz and Edwards in 1999, which stood for the fine-tuning or modulation of nerve cell transmission. In 2000-2010, Ribeiro and Sebastiao, based on a series of papers, provided strong support for their view that adenosine can meta-modulate (fine-tune) synaptic transmission through adenosine receptors. However, another term should also be considered: protein modulation, which is the key feature of allosteric receptor-receptor interactions leading to learning and consolidation by novel adapter proteins to memory. Finally, it must be underlined that allosteric receptor-receptor interactions and their involvement both in brain disease and its treatment are of high interest. Their pathophysiological relevance has been obtained, especially for major depressive disorder, cocaine use disorder, and Parkinson's disease.

Dynamics of Single-Cell Protein Covariation during Epithelial-Mesenchymal Transition.

Physiological processes, such as the epithelial-mesenchymal transition (EMT), are mediated by changes in protein interactions. These changes may be better reflected in protein covariation within a cellular cluster than in the temporal dynamics of cluster-average protein abundance. To explore this possibility, we quantified proteins in single human cells undergoing EMT. Covariation analysis of the data revealed that functionally coherent protein clusters dynamically changed their protein-protein correlations without concomitant changes in the cluster-average protein abundance. These dynamics of protein-protein correlations were monotonic in time and delineated protein modules functioning in actin cytoskeleton organization, energy metabolism, and protein transport. These protein modules are defined by protein covariation within the same time point and cluster and, thus, reflect biological regulation masked by the cluster-average protein dynamics. Thus, protein correlation dynamics across single cells offers a window into protein regulation during physiological transitions.