Endogenous Inhibitor Research Articles

Characterization and mechanism of seed dormancy in Symplocos paniculata.

Symplocos paniculata is a highly desirable oil species for biodiesel and premium edible oil feedstock. While germplasm preservation and breeding are crucial, the severity of seed dormancy poses a challenge to successful germination. We employed S. paniculata seeds as experimental materials and conducted an investigation into the types and causes of seed dormancy by analyzing the morphology and developmental characteristics of its embryo, exploring the water permeability property of the endocarp, and examining the presence of endogenous inhibitors, aiming to establish a theoretical foundation for overcoming seed dormancy and maximizing germplasm resource utilization. The findings revealed that the seed embryo had matured into a fully developed embryo, and no dormancy in terms of embryo morphology was observed. Upon reaching maturity, the endocarp of seeds undergoes significant lignification, resulting in notable differences in water absorption between cracked and intact seeds. The impermeability of the endocarp is one of the factors contributing to mechanical restriction. The different phases of endosperm extraction exerted varying effects on the germination of Chinese cabbage seeds, with the methanol phase exhibiting the most potent inhibitory effect. The presence of endogenous inhibitors emerged as the primary factor contributing to physiological dormancy in seeds. GC-MS analysis and validation trials revealed that fatty acids and phenolics, including hexadecanoic acid, oxadecanoic acid, and m-cresol, constituted the main types of endogenous inhibitory compounds found within the endosperm. These findings suggest that the seed dormancy in S. paniculata seeds has endocarp mechanical restriction, and the presence of endogenous inhibitors causes physiological dormancy.

The Clinical Development of Taldefgrobep Alfa: An Anti-Myostatin Adnectin for the Treatment of Duchenne Muscular Dystrophy.

Duchenne muscular dystrophy (DMD) is a genetic muscle disorder that manifests during early childhood and is ultimately fatal. Recently approved treatments targeting the genetic cause of DMD are limited to specific subpopulations of patients, highlighting the need for therapies with wider applications. Pharmacologic inhibition of myostatin, an endogenous inhibitor of muscle growth produced almost exclusively in skeletal muscle, has been shown to increase muscle mass in several species, including humans. Taldefgrobep alfa is an anti-myostatin recombinant protein engineered to bind to and block myostatin signaling. Preclinical studies of taldefgrobep alfa demonstrated significant decreases in myostatin and increased lower limb volume in three animal species, including dystrophic mice. This manuscript reports the cumulative data from three separate clinical trials of taldefgrobep alfa in DMD: a phase1 study in healthy adult volunteers (NCT02145234), and two randomized, double-blind, placebo-controlled studies in ambulatory boys with DMD-a phase1b/2 trial assessing safety (NCT02515669) and a phase2/3 trial including the North Star Ambulatory Assessment (NSAA) as the primary endpoint (NCT03039686). In healthy adult volunteers, taldefgrobep alfa was generally well tolerated and resulted in a significant increase in thigh muscle volume. Treatment with taldefgrobep alfa was associated with robust dose-dependent suppression of free myostatin. In the phase1b/2 trial, myostatin suppression was associated with a positive effect on lean body mass, though effects on muscle mass were modest. The phase2/3 trial found that the effects of treatment did not meet the primary endpoint pre-specified futility analysis threshold (change from baseline of ≥ 1.5 points on the NSAA total score). The futility analysis demonstrated that taldefgrobep alfa did not result in functional change for boys with DMD. The program was subsequently terminated in 2019. Overall, there were no safety concerns, and no patients were withdrawn from treatment as a result of treatment-related adverse events or serious adverse events. NCT02145234, NCT02515669, NCT03039686.

Inhibition of phosphatidylinositol 3-kinase catalytic subunit alpha by miR-203a-3p reduces hypertrophic scar formation via phosphatidylinositol 3-kinase/AKT/mTOR signaling pathway.

Hypertrophic scar (HS) is a common fibroproliferative skin disease that currently has no truly effective therapy. Given the importance of phosphatidylinositol 3-kinase catalytic subunit alpha (PIK3CA) in hypertrophic scar formation, the development of therapeutic strategies for endogenous inhibitors against PIK3CA is of great interest. Here, we explored the molecular mechanisms underlying the protective effects of miR-203a-3p (PIK3CA inhibitor) against excessive scar. Bioinformatic analysis, immunohistochemistry, immunofluorescence, miRNA screening and fluorescence in situ hybridization assays were used to identify the possible pathways and target molecules mediating HS formation. A series of in vitro and in vivo experiments were used to clarify the role of PIK3CA and miR-203a-3p in HS. Mechanistically, transcriptomic sequencing, immunoblotting, dual-luciferase assay and rescue experiments were executed. Herein, we found that PIK3CA and the phosphatidylinositol 3-kinase (PI3K)/AKT/mTOR pathway were upregulated in scar tissues and positively correlated with fibrosis. We then identified miR-203a-3p as the most suitable endogenous inhibitor of PIK3CA. miR-203a-3p suppressed the proliferation, migration, collagen synthesis and contractility as well as the transdifferentiation of fibroblasts into myofibroblasts in vitro, and improved the morphology and histology of scars in vivo. Mechanistically, miR-203a-3p attenuated fibrosis by inactivating the PI3K/AKT/mTOR pathway by directly targeting PIK3CA. PIK3CA and the PI3K/AKT/mTOR pathway are actively involved in scar fibrosis and miR-203a-3p might serve as a potential strategy for hypertrophic scar therapy through targeting PIK3CA and inactivating the PI3K/AKT/mTOR pathway.

A human embryonic stem cell-based model reveals the cell of origin of FOXR2-activated CNS neuroblastoma.

FOXR2-activated central nervous system (CNS) neuroblastoma (CNS NB-FOXR2) is a recently identified subtype of brain tumor characterized by the elevated expression of the transcription factor FOXR2 mainly due to genomic rearrangements. However, the precise pathogenic mechanisms, including the cell type of origin, remain elusive. A gene expression analysis of patient tumors was performed to identify putative cell types of origin. Based on this prediction, a new human embryonic stem cell-based model was developed to validate the origin and to examine the molecular and cellular mechanisms underlying the formation of CNS NB-FOXR2. Our data showed that CNS NB-FOXR2 tumors express a high level of lineage marker genes associated with the medial ganglionic eminence (MGE), a transient structure located in the developing ventral forebrain. Our model confirmed the cell-type-specific effect of FOXR2 on the proliferation and in vivo tumorigenicity. Additionally, we found that FOXR2 overexpression activated the MEK/ERK signaling pathway through a suppression of the endogenous RAS inhibitor DIRAS3. The MEK inhibitor trametinib suppressed the proliferation of FOXR2-expressing MGE progenitors more than nonexpressing cells. Our study collectively demonstrates that MGE progenitors are the cell of origin of CNS NB-FOXR2 and that FOXR2 activates the MEK/ERK signaling pathway, providing a potential therapeutic target.

Therapeutic potential of elafin in airway inflammatory disease

Elafin, which is derived from trappin-2 or pre-elafin by proteolysis, is an endogenous serine protease inhibitor with a low molecular weight. Its inhibitory activity is dependent on anchoring to the extracellular matrix by forming covalent bonds with its distinctive N-terminal domain via tissue transglutaminases. In addition to inhibiting proteases, it also exhibits anti-inflammatory, antibiotic, antifungal, antiviral and immunomodulatory functions. Elafin plays an important role in inflammatory disease and is a promising candidate for the anti-inflammatory treatment of respiratory diseases. This review will discuss the therapeutic potential of elafin in airway inflammation and provide evidence and suggestions for the future treatment of airway inflammatory diseases. In addition, the therapeutic potential of elafin in lung cancer is also discussed.

HSPA12A acts as a scaffolding protein to inhibit cardiac fibroblast activation and cardiac fibrosis

IntroductionCardiac fibrosis is the main driver for adverse remodeling and progressive functional decline in nearly all types of heart disease including myocardial infarction (MI). The activation of cardiac fibroblasts (CF) into myofibroblasts is responsible for cardiac fibrosis. Unfortunately, no ideal approach for controlling CF activation currently exists. ObjectivesThis study investigated the role of Heat shock protein A12A (HSPA12A), an atypical member of the HSP70 family, in CF activation and MI-induced cardiac fibrosis. MethodsPrimary CF and Hspa12a knockout mice were used in the experiments. CF activation was indicated by the upregulation of myofibroblast characters including alpha-Smooth muscle actin (αSMA), Collagen, and Fibronectin. Cardiac fibrosis was illustrated by Masson’s trichrome and picrosirius staining. Cardiac function was examined using echocardiography. Glycolytic activity was indicated by levels of extracellular lactate and the related protein expression. Protein stability was examined following cycloheximide and MG132 treatment. Protein-protein interaction was examined by immunoprecipitation-immunoblotting analysis. ResultsHSPA12A displayed a high expression level in quiescent CF but showed a decreased expression in activated CF, while ablation of HSPA12A in mice promoted CF activation and cardiac fibrosis following MI. HSPA12A overexpression inhibited the activation of primary CF through inhibiting glycolysis, while HSPA12A knockdown showed the opposite effects. Moreover, HSPA12A upregulated the protein expression of transcription factor p53, by which mediated the HSPA12A-induced inhibition of glycolysis and CF activation. Mechanistically, this action of HSPA12A was achieved by acting as a scaffolding protein to bind p53 and ubiquitin specific protease 10 (USP10), thereby promoting the USP10-mediated p53 protein stability and the p53-medicated glycolysis inhibition. ConclusionThe present study provided clear evidence that HSPA12A is a novel endogenous inhibitor of CF activation and cardiac fibrosis. Targeting HSPA12A in CF could represent a promising strategy for the management of cardiac fibrosis in patients.

The biological function of Serpinb9 and Serpinb9-based therapy.

Recent breakthroughs in discovering novel immune signaling pathways have revolutionized different disease treatments. SERPINB9 (Sb9), also known as Proteinase Inhibitor 9 (PI-9), is a well-known endogenous inhibitor of Granzyme B (GzmB). GzmB is a potent cytotoxic molecule secreted by cytotoxic T lymphocytes and natural killer cells, which plays a crucial role in inducing apoptosis in target cells during immune responses. Sb9 acts as a protective mechanism against the potentially harmful effects of GzmB within the cells of the immune system itself. On the other hand, overexpression of Sb9 is an important mechanism of immune evasion in diseases like cancers and viral infections. The intricate functions of Sb9 in different cell types represent a fine-tuned regulatory mechanism for preventing immunopathology, protection against autoimmune diseases, and the regulation of cell death, all of which are essential for maintaining health and responding effectively to disease challenges. Dysregulation of the Sb9 will disrupt human normal physiological condition, potentially leading to a range of diseases, including cancers, inflammatory conditions, viral infections or other pathological disorders. Deepening our understanding of the role of Sb9 will aid in the discovery of innovative and effective treatments for various medical conditions. Therefore, the objective of this review is to consolidate current knowledge regarding the biological role of Sb9. It aims to offer insights into its discovery, structure, functions, distribution, its association with various diseases, and the potential of nanoparticle-based therapies targeting Sb9.

Rem2 interacts with CaMKII at synapses and restricts long-term potentiation in hippocampus.

Synaptic plasticity, the process whereby neuronal connections are either strengthened or weakened in response to stereotyped forms of stimulation, is widely believed to represent the molecular mechanism that underlies learning and memory. The holoenzyme calcium/calmodulin-dependent protein kinase II (CaMKII) plays a well-established and critical role in the induction of a variety of forms of synaptic plasticity such as long-term potentiation (LTP), long-term depression (LTD) and depotentiation. Previously, we identified the GTPase Rem2 as a potent, endogenous inhibitor of CaMKII. Here, we report that knock out of Rem2 enhances LTP at the Schaffer collateral to CA1 synapse in hippocampus, consistent with an inhibitory action of Rem2 on CaMKII in vivo. Further, re-expression of WT Rem2 rescues the enhanced LTP observed in slices obtained from Rem2 conditional knock out (cKO) mice, while expression of a mutant Rem2 construct that is unable to inhibit CaMKII in vitro fails to rescue increased LTP. In addition, we demonstrate that CaMKII and Rem2 interact in dendritic spines using a 2pFLIM-FRET approach. Taken together, our data lead us to propose that Rem2 serves as a brake on synaptic potentiation via inhibition of CaMKII activity. Further, the enhanced LTP phenotype we observe in Rem2 cKO slices reveals a previously unknown role for Rem2 in the negative regulation of CaMKII function.

GABA and nitric oxide reduce AsV toxicity in tomato and brinjal seedlings by regulating sulphur assimilation and proline metabolism

Arsenate (AsV) is one of the most hazardous elements, and its increasing accumulation in plants is the major area of concern in present days. Therefore, an environmentally reliable approach is required to reduce the load of AsV into vegetables. In the current study, the potential role of gamma amino butyric acid (GABA; 10 µM) and sodium nitroprusside a donor of NO (SNP; 10 µM) in 21 days old seedlings of tomato and brinjal grown in Hoagland medium containing 25 µM of AsV was analysed by estimating physiological and biochemical attributes. AsV exposure reduced root and shoot length and dry mass by 18, 9 % and 15 % in tomato, and 23 and 10 %, and 27 % in brinjal seedlings, respectively. Additionally, AsV decreased leaf gas exchange parameters i.e. stomatal conductance, internal CO2 concentration, transpiration rate and subsequently photosynthetic rate. Although AsV stimulated sulphur assimilation and proline metabolism, but it raised the oxidative stress as evident by increased biomarkers; superoxide radicals (SOR), hydrogen peroxide (H2O2), lipid peroxidation (MDA), and protein oxidation in both the seedlings. The application of GABA and SNP significantly mitigated negative effects of AsV on both the vegetables. The results indicate that GABA was unable to reduce AsV stress in the presence of L-NAME (an endogenous NO biosynthetic inhibitor), but addition of SNP rescued the effect of L-NAME. Overall, the findings suggest that GABA and SNP effectively mitigate AsV stress however, the involvement of NO appears to be necessary for GABA to achieve this task efficiently in the studied vegetables. These results will help to design strategies for mitigating arsenate stress in vegetable crops.

Clinical Significance of Frequently Down-Regulated Phosphatidylethanolamine-Binding Protein-1 in Gallbladder Cancer.

Promoter hypermethylation of tumor suppressor genes has been demonstrated to be one of the major mechanisms of their epigenetic regulation in various reports. We have studied the promoter methylation status of PEBP1 and evaluated its correlation with gallbladder carcinogenesis. PEBP1, an endogenous inhibitor of Raf/MEK/ERK signaling pathway, is a tumor suppressor gene. We aimed to study the expression profile of PEBP1 and understand the mechanism and significance of its deregulation in gallbladder cancer. PEBP1 expression analysis and its promoter methylation status were investigated in 77 gallbladder carcinoma (GBC) and tissue biopsies from 28 patients of gallstone disease by RT-PCR and MS-PCR, respectively. Our results of the mRNA expression profiling demonstrate that PEBP1 is down-regulated in 62.3% (48/77), while 31.2% (24/77) of the gallbladder cancer biopsies show no significant change and 6.5% (5/77) show up-regulated expression compared to tissue samples of gallstone diseases. In GBC, 48.1% (N = 37) GBC biopsy samples exhibited significantly heterozygous promoter hypermethylation compared to tissue samples from gallstone diseases which show promoter hypermethylation in 3 (10.7%) samples only. In gallbladder cancer, the PEBP1 methylation is significantly associated with lymph node metastasis and shorter period of survival. PEBP1 is frequently down-regulated and hypermethylated in gallbladder cancer and its promoter hypermethylation is a frequent and early inactivating mechanism in GBC.

Lipolysis products from triglyceride-rich lipoproteins induce stress protein ATF3 in osteoblasts.

High fat diets overwhelm the physiological mechanisms for absorption, storage, and utilization of triglycerides (TG); consequently TG, TG-rich lipoproteins (TGRL), and TGRL remnants accumulate, circulate systemically, producing dyslipidemia. This associates with, or is causative for increased atherosclerotic cardiovascular risk, ischemic stroke, fatty liver disease, and pancreatitis. TGRL hydrolysis by endothelial surface-bound lipoprotein lipase (LPL) generates metabolites like free fatty acids which have proinflammatory properties. While osteoblasts utilize fatty acids as an energy source, dyslipidemia is associated with negative effects on the skeleton. In this study we investigated the effects of TGRL lipolysis products (TGRL-LP) on expression of a stress responsive transcription factor, termed activating transcription factor 3 (ATF3), reactive oxygen species (ROS), ATF3 target genes, and angiopoietin-like 4 (Angptl4) in osteoblasts. As ATF3 negatively associates with osteoblast differentiation, we also investigated the skeletal effects of global ATF3 deletion in mice. TGRL-LPincreased expression of Atf3, proinflammatory proteins Ptgs2 and IL-6, and induced ROS in MC3T3-E1 osteoblastic cells. Angptl4 is an endogenous inhibitor of LPL which was transcriptionally induced by TGRL-LP, while recombinant Angptl4 prevented TG-driven Atf3 induction. Atf3 global knockout male mice demonstrated increased trabecular and cortical microarchitectural parameters. In summary, we find that TGRL-LP induce osteoblastic cell stress as evidenced by expression of ATF3, which may contribute to the negative impact of dyslipidemia in the skeleton. Further, concomitant induction of Angptl4 in osteoblasts might play a protective role by reducing local lipolysis.

NLRP3/1-mediated pyroptosis: beneficial clues for the development of novel therapies for Alzheimer's disease.

The inflammasome is a multiprotein complex involved in innate immunity that mediates the inflammatory response leading to pyroptosis, which is a lytic, inflammatory form of cell death. There is accumulating evidence that nucleotide-binding domain and leucine-rich repeat pyrin domain containing 3 (NLRP3) inflammasome-mediated microglial pyroptosis and NLRP1 inflammasome-mediated neuronal pyroptosis in the brain are closely associated with the pathogenesis of Alzheimer's disease. In this review, we summarize the possible pathogenic mechanisms of Alzheimer's disease, focusing on neuroinflammation. We also describe the structures of NLRP3 and NLRP1 and the role their activation plays in Alzheimer's disease. Finally, we examine the neuroprotective activity of small-molecule inhibitors, endogenous inhibitor proteins, microRNAs, and natural bioactive molecules that target NLRP3 and NLRP1, based on the rationale that inhibiting NLRP3 and NLRP1 inflammasome-mediated pyroptosis can be an effective therapeutic strategy for Alzheimer's disease.

The Contribution of Tissue Inhibitor of Metalloproteinase-2 Genotypes to Breast Cancer Risk in Taiwan.

Tissue inhibitor of metalloproteinase-2 (TIMP-2) is an endogenous inhibitor of matrix metalloproteinase-2 and is highly expressed in breast cancer (BC) cases at diagnosis. However, the genetic investigations for the association of TIMP-2 genotypes with BC risk are rather limited. In this study, contribution of TIMP-2 rs8179090, rs4789936, rs2009196 and rs7342880 genotypes to BC risk was examined among Taiwan's BC population. TIMP-2 genotypic profiles were revealed among 1232 BC cases and 1232 controls about their contribution to BC using a PCR-based RFLP methodology. The TIMP-2 rs8179090 homozygous variant CC genotype was significantly higher in BC cases than controls (odds ratio (OR) = 2.76, 95% confidence interval (95%CI) = 1.78-4.28, p = 0.0001). Allelic analysis showed that C allele carriers have increased risk for BC (OR = 1.39, 95%CI = 1.20-1.62, p = 0.0001). Genotypic together with allelic analysis showed that TIMP-2 rs4789936, rs2009196 or rs7342880 were not associated with BC risk. Stratification analysis showed that TIMP-2 rs8179090 genotypes were significantly associated with BC risk among younger (≤55) aged women, not among those of an elder (>55) age. Last, rs8179090 genotypes were also associated with triple negative BC. This study sheds light into the etiology of BC in Taiwanese women. Rs8179090 may be incorporated into polygenic risk scores and risk prediction models, which could aid in stratifying individuals for targeted breast cancer screening.

Rational design of proteasome inhibitors based on the structure of the endogenous inhibitor PI31/Fub1.

Proteasome inhibitors are widely used anticancer drugs. The three clinically approved agents are modified small peptides that preferentially target one of the proteasome's three active sites (β5) at physiologic concentrations. In addition to these drugs, there is also an endogenous proteasome inhibitor, PI31/Fub1, that enters the proteasome's interior to simultaneously yet specifically inhibit all three active sites. Here, we have used PI31's evolutionarily optimized inhibitory mechanisms to develop a suite of potent and specific β2 inhibitors. The lead compound strongly inhibited growth of multiple myeloma cells as a standalone agent, indicating the compound's cell permeability and establishing β2 as a potential therapeutic target in multiple myeloma. The lead compound also showed strong synergy with the existing β5 inhibitor bortezomib; such combination therapies might help with existing challenges of resistance and severe side effects. These results represent an effective method for rational structure-guided development of proteasome inhibitors.

Matrix metalloproteinases system profile analysis and their endogenous inhibitors in children with periodontal diseases and various dysplasia phenotypes

Relevance. The search and development of modern non-invasive methods for early periodontal disease detection are of scientific and practical value for a personalized approach to disease course prognosis and explaining the choice of treatment tactics. Morphological immaturity, high intensity of anabolic processes, functional failure of neurohumoral, endocrine and immunological defence systems combined with an imbalance between the synthesis and degradation of extracellular matrix components in children with undifferentiated connective tissue disease (UCTD) significantly increases the risk of developing periodontal diseases. The available data on the activity of salivary matrix metalloproteinases (MMPs), which play a leading role in regulating connective tissue protein metabolism and bone remodelling mechanisms in children with UCTD of various degrees, are scarce and require further study.Purpose. The study aimed to explain the clinical, diagnostic and prognostic value of MMPs as markers of inflammatory periodontal diseases in children with UC TD and dysplastic disorders of various se verity.Material and methods. The study included 67 children with UCTD (main group) and 34 children of health groups I and II (comparison group) aged 12-17. The UCTD severity was established according to the diagnostic criteria by L. N. Abbakumova (2006) and a scale for assessing the significance of phenotypic and visceral signs. The main group was divided into two subgroups: Subgroup 1 (n = 38) – children with mild and moderate UCTD; Subgroup 2 (n=29) – children with severe UCTD. The studied groups had their periodontal status assessed, as well as the concentration of MMP-1, MMP-2, MMP-8, MMP-9 and their tissue inhibitors (TIMP-1, TIMP-2) in the oral fluid identified using the enzyme immunoassay, along with calculation done for the MMP ⁄ TIMP coefficients that set a balance between the degradation and synthesis of collagen.Results. The children with phenotypic signs of UCTD in the oral fluid appeared to show a statistically significant increase in the MMP-1, MMP-2, MMP-8, and MMP-9 levels and an imbalanced ratio in MMP-1⁄TIMP-1, MMP- 2⁄TIMP-2, MMP-8⁄TIMP-1, MMP-9⁄TIMP-1, compared with health groups I, II. An increase in the MMP-1, MMP-2, and MMP-8 concentrations, along with dominating expression of MMP-9 over TIMP-1 in the oral fluid of children of Subgroup 2, causes an increase in intensity and prevalence of periodontal diseases compared to the patients in Sub-group 1 and comparison group.Conclusion. Thus, when children with UCTD don’t demonstrate an increase in specific tissue inhibitors TIMP-1 and TIMP-2 in their oral fluid, along with an increase in the levels of the respective matrixins is the key pathogenetic factor in the degradation of extracellular matrix proteins, which causes a depressing impact on the proliferative activity in the periodontal set of tissues.

Eosinophilic Chronic Rhinosinusitis and Pathogenic Role of Protease.

Chronic rhinosinusitis (CRS) is an inflammation of the nasal and paranasal sinus mucosa, and eosinophilic CRS (eCRS) is a subtype characterized by significant eosinophil infiltration and immune response by T-helper-2 cells. The pathogenesis of eCRS is heterogeneous and involves various environmental and host factors. Proteases from external sources, such as mites, fungi, and bacteria, have been implicated in inducing type 2 inflammatory reactions. The balance between these proteases and endogenous protease inhibitors (EPIs) is considered important, and their imbalance can potentially lead to type 2 inflammatory reactions, such as eCRS. In this review, we discuss various mechanisms by which exogenous proteases influence eCRS and highlight the emerging role of endogenous protease inhibitors in eCRS pathogenesis.

BIOMEDICAL APPLICATION OF K5 PLASMINOGEN FRAGMENT

Aim. Plasminogen kringle 5 is an endogenous angiogenic inhibitor. The purpose of the present review was to highlight the potential biomedical application of kringle 5 in the regulation of angiogenesis and tumor growth. Methods. Angiogenesis is a complex process that involves endothelial cell proliferation, migration, basement membrane degradation, and neovessel organization. Since the uncontrolled growth of new blood vessels causes the progression of many common diseases, first of all, oncological diseases, autoimmune disorders, neovascular damage of the eye, the use of angiostatins can be a promising pharmacotherapeutic approach to the prevention and adjuvant therapy of these pathological conditions. The advantages of angiostatins application are their non-toxicity even at high doses, non-immunogenicity, lack of tolerance of target cells to their action. Angiostatins comprise a group of kringle-containing proteolytically-derived fragments of plasminogen/plasmin, which act as potent inhibitory mediators of endothelial proliferation and migration. Among all known angiostatin species, isolated K5 plasminogen fragment was shown to display the most potent inhibitory activity against proliferation of endothelial cells via triggering multiple signaling pathways, which lead to cell death and resulting angiogenesis suppression. Results. Current literature data suggest that in addition to expressed and highly specific cytotoxicity in relation to endotheliocytes and some types of tumor cells, the kringle domain 5 of human plasminogen has other advantages as an antiangiogenic and antitumor regulator, including its specific inhibitory activity, which affects only activated, proliferating endothelial cells, and therefore is non-toxic to other types of normal cells. As an endogenous protein, which is formed in the human organism, K5 does not provoke an immune response. K5 as a small polypeptide molecule with a stable structure can be obtained as a recombinant protein in E. coli cells, and can also be used in pharmacokinetic systems of targeted delivery and sustained release. Conclusions. The prospect of successful use of K5 as a therapeutic agent to manage pathological processes associated with dysregulation of angiogenesis makes it necessary to develop and improve methods of its production and to further test its plausible pleiotropic biological activities.

MMP‐2 regulates Src activation via repression of the CHK/MATK tumor suppressor in osteosarcoma

AbstractBackgroundDoxorubicin, a first‐line anticancer drug for osteosarcoma treatment, has been the subject of recent research exploring the mechanisms behind its chemoresistance and its ability to enhance cell migration at sublethal concentrations. Matrix metalloproteinase‐2 (MMP‐2), a type IV collagenase and zinc‐dependent endopeptidase, is well‐known for degrading the extracellular matrix and promoting cancer metastasis. Our previous work demonstrated that nuclear MMP‐2 regulates ribosomal RNA transcription via histone clipping, thereby controlling gene expression. Additionally, MMP‐2 activity is regulated by the non‐receptor tyrosine kinase and oncogene, Src, which plays a crucial role in cell adhesion, invasion, and metastasis. Src kinase is primarily regulated by two endogenous inhibitors: C‐terminal Src kinase (Csk) and Csk homologous kinase (CHK/MATK).AimIn this study, we reveal that the MMP‐2 gene acts as an upstream regulator of Src kinase activity by suppressing its endogenous inhibitor, CHK/MATK, in osteosarcoma cells.Methods and ResultsWe show that enhanced osteosarcoma cell migration which is induced by sublethal concentrations of doxorubicin can be overcome by inactivating the MMP‐2 gene or overexpressing CHK/MATK. Our findings highlight the MMP‐2 gene as a promising additional target for combating cancer cell migration and metastasis. This is due to its role in suppressing on the gene and protein expression of the tumor suppressor CHK/MATK in osteosarcoma.ConclusionBy targeting the MMP‐2 gene, we can potentially enhance the effectiveness of doxorubicin treatment and reduce chemoresistance in osteosarcoma.

Specific inhibition on PAI-1 reduces the dose of Alteplase for ischemic stroke treatment

Administration of recombinant tPA (rtPA, or trade name Alteplase®) is an FDA-approved therapy for acute ischemic stroke (AIS), but poses the risk of hemorrhagic complications. Recombinant tPA can be rapidly inactivated by the endogenous inhibitor, plasminogen activator inhibitor 1 (PAI-1). In this work, we study a novel treatment approach that combines a PAI-1 inhibitor, PAItrap4, with a reduced dose of rtPA to address the hemorrhagic concern of rtPA. PAItrap4 is a highly specific and very potent protein-based inhibitor of PAI-1, comprising of a variant of uPA serine protease domain, human serum albumin, and a cyclic RGD peptide. PAItrap4 efficiently targets and inhibits PAI-1 on activated platelets, and also possesses a long half-life in vivo. Our results demonstrate that PAItrap4 effectively counteracts the inhibitory effects of PAI-1 on rtPA, preserving rtPA activity based on amidolytic and clot lysis assays. In an in vivo murine stroke model, PAItrap4, together with low-dose rtPA, enhances the blood perfusion in the stroke-affected areas, reduces infarct size, and promotes neurological recovery in mice. Importantly, such treatment does not increase the amount of cerebral hemorrhage, thus reducing the risk of cerebral hemorrhage. In addition, PAItrap4 does not compromise the normal blood coagulation function in mice, demonstrating its safety as a therapeutic agent. These findings highlight this combination therapy as a promising alternative for the treatment of ischemic stroke, offering improved safety and efficacy.

Simvastatin restores pulmonary endothelial function in the setting of pulmonary over-circulation

Statin therapy is a cornerstone in the treatment of systemic vascular diseases. However, statins have failed to translate as therapeutics for pulmonary vascular disease. Early pulmonary vascular disease in the setting of congenital heart disease (CHD) is characterized by endothelial dysfunction, which precedes the more advanced stages of vascular remodeling. These features make CHD an ideal cohort in which to re-evaluate the potential pulmonary vascular benefits of statins, with a focus on endothelial biology. However, it is critical that the full gamut of the pleiotropic effects of statins in the endothelium are uncovered. The purpose of this investigation was to evaluate the therapeutic potential of simvastatin for children with CHD and pulmonary over-circulation, and examine mechanisms of simvastatin action on the endothelium. Our data demonstrate that daily simvastatin treatment preserves endothelial function in our shunt lamb model of pulmonary over-circulation. Further, using pulmonary arterial endothelial cells (PAECs) isolated from Shunt and control lambs, we identified a new mechanism of statin action mediated by increased expression of the endogenous Akt1 inhibitor, C-terminal modifying protein (CTMP). Increases in CTMP were able to decrease the Akt1-mediated mitochondrial redistribution of endothelial nitric oxide synthase (eNOS) which correlated with increased enzymatic coupling, identified by increases in NO generation and decreases in NOS-derived superoxide. Together our data identify a new mechanism by which simvastatin enhances NO signaling in the pulmonary endothelium and identify CTMP as a potential therapeutic target to prevent the endothelial dysfunction that occurs in children born with CHD resulting in pulmonary over-circulation.