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Journal of Thrombosis and Haemostasis :... Apr 2022Antiproteinases such as alpha-2-macroglobulin (A2M) play a role in hemostasis. A2M is highly conserved throughout evolution and is a high molecular weight... (Review)
Review
Antiproteinases such as alpha-2-macroglobulin (A2M) play a role in hemostasis. A2M is highly conserved throughout evolution and is a high molecular weight homo-tetrameric glycoprotein. A2M proteinase inhibitor activity is possible via a unique cage structure leading to proteinase entrapment without direct enzymatic activity inhibition. Following this entrapment, proteinase clearance is possible through A2M binding to the low-density lipoprotein receptor-related protein 1. A2M synthesis is regulated by pro-inflammatory cytokines and increases during several chronic or acute inflammatory diseases and varies with age. For instance, A2M plasma levels are known to be increased in patients with diabetes mellitus, nephrotic syndrome, or sepsis. Concerning hemostasis, A2M can trap many proteinases involved in coagulation and fibrinolysis. Because of its pleiotropic effects A2M can be seen as both anti- and pro-hemostatic. A2M can inhibit thrombin, factor Xa, activated protein C, plasmin, tissue-plasminogen activator, and urokinase. Through its many different functions A2M is generally put apart in the balanced regulation of hemostasis. In addition, the fact that A2M plasma levels are differently regulated during inflammatory-related diseases and that A2M can neutralize cytokines that also modify hemostasis could explain why it is difficult to link common proteins and parameters of hemostasis with the mechanisms of thrombosis in such diseases. Thus, we propose in the present review to summarize known functions of A2M, give a brief overview about diseases, and then to focus on the roles of this antiproteinase in hemostasis and thrombosis.
Topics: Cytokines; Female; Hemostasis; Humans; Pregnancy; Pregnancy-Associated alpha 2-Macroglobulins; Thrombin; Thrombosis; Transcription Factors; alpha-Macroglobulins
PubMed: 35037393
DOI: 10.1111/jth.15647 -
American Journal of Physiology. Heart... Apr 2022Both skin wound healing and the cardiac response to myocardial infarction (MI) progress through similar pathways involving inflammation, resolution, tissue repair, and...
Both skin wound healing and the cardiac response to myocardial infarction (MI) progress through similar pathways involving inflammation, resolution, tissue repair, and scar formation. Due to the similarities, we hypothesized that the healing response to skin wounding would predict future response to MI. Mice were given a 3-mm skin wound using a disposable biopsy punch and the skin wound was imaged daily until closure. The same set of animals was given MI by permanent coronary artery ligation 28 days later and followed for 7 days. Cardiac physiology was measured by echocardiography at baseline and MI and . Animals that survived until were grouped as survivors, and animals that died from MI were grouped as nonsurvivors. Survivors had faster skin wound healing than nonsurvivors. Faster skin wound healing predicted MI survival better than commonly used cardiac functional variables (e.g., infarct size, fractional shortening, and end diastolic dimension). -glycoproteome profiling of MI plasma revealed α-macroglobulin and ELL-associated factor 1 as strong predictors of future MI death and progression to heart failure. A second cohort of MI mice validated these findings. To investigate the clinical relevance of α-macroglobulin, we mapped the plasma glycoproteome in patients with MI 48 h after admission and in healthy controls. In patients, α-macroglobulin was increased 48 h after MI. Apolipoprotein D, another plasma glycoprotein, detrimentally regulated both skin and cardiac wound healing in male but not female mice by promoting inflammation. Our results reveal that the skin is a mirror to the heart and common pathways link wound healing across organs. Faster skin wound healers had more efficient cardiac healing after myocardial infarction (MI). Two plasma proteins at MI, EAF1 and A2M, predicted MI death in 66% of cases. ApoD regulated both skin and cardiac wound healing in male mice by promoting inflammation. The skin was a mirror to the heart and common pathways linked wound healing across organs.
Topics: Animals; Humans; Inflammation; Macroglobulins; Male; Mice; Mice, Inbred C57BL; Myocardial Infarction; Myocardium; Transcription Factors; Ventricular Remodeling; Wound Healing
PubMed: 35089808
DOI: 10.1152/ajpheart.00612.2021 -
Oxidative Medicine and Cellular... 2019Alpha-macroglobulins are ancient proteins that include monomeric, dimeric, and tetrameric family members. In humans, and many other mammals, the predominant... (Review)
Review
Alpha-macroglobulins are ancient proteins that include monomeric, dimeric, and tetrameric family members. In humans, and many other mammals, the predominant alpha-macroglobulin is alpha-2-macroglobulin ( M), a tetrameric protein that is constitutively abundant in biological fluids (e.g., blood plasma, cerebral spinal fluid, synovial fluid, ocular fluid, and interstitial fluid). M is best known for its remarkable ability to inhibit a broad spectrum of proteases, but the full gamut of its activities affects diverse biological processes. For example, M can stabilise and facilitate the clearance of the Alzheimer's disease-associated amyloid beta (A) peptide. Additionally, M can influence the signalling of cytokines and growth factors including neurotrophins. The results of several studies support the idea that the functions of M are uniquely regulated by hypochlorite, an oxidant that is generated during inflammation, which induces the native M tetramer to dissociate into dimers. This review will discuss the evidence for hypochlorite-induced regulation of M and the possible implications of this in neuroinflammation and neurodegeneration.
Topics: Amyloid beta-Peptides; Animals; Humans; Hypochlorous Acid; Immune System; Neurodegenerative Diseases; Peptide Hydrolases; Pregnancy-Associated alpha 2-Macroglobulins; Protein Binding; Signal Transduction
PubMed: 31428227
DOI: 10.1155/2019/5410657 -
Journal of Molecular Biology Mar 2022Alpha-2-Macroglobulin (A2M) is the critical pan-protease inhibitor of the innate immune system. When proteases cleave the A2M bait region, global structural...
Alpha-2-Macroglobulin (A2M) is the critical pan-protease inhibitor of the innate immune system. When proteases cleave the A2M bait region, global structural transformation of the A2M tetramer is triggered to entrap the protease. The structural basis behind the cleavage-induced transformation and the protease entrapment remains unclear. Here, we report cryo-EM structures of native- and intermediate-forms of the Xenopus laevis egg A2M homolog (A2Moo or ovomacroglobulin) tetramer at 3.7-4.1 Å and 6.4 Å resolution, respectively. In the native A2Moo tetramer, two pairs of dimers arrange into a cross-like configuration with four 60 Å-wide bait-exposing grooves. Each bait in the native form threads into an aperture formed by three macroglobulin domains (MG2, MG3, MG6). The bait is released from the narrowed aperture in the induced protomer of the intermediate form. We propose that the intact bait region works as a "latch-lock" to block futile A2M transformation until its protease-mediated cleavage.
Topics: Cryoelectron Microscopy; Peptide Hydrolases; Protein Conformation; Protein Multimerization; Proteolysis; Transcription Factors; Xenopus Proteins; alpha-Macroglobulins
PubMed: 34942166
DOI: 10.1016/j.jmb.2021.167413 -
Scientific Reports Sep 2019α-Macroglobulin is a highly abundant serum protein involved in the development of atherosclerosis and cardiac hypertrophy. However, its circulating molecular form and...
α-Macroglobulin is a highly abundant serum protein involved in the development of atherosclerosis and cardiac hypertrophy. However, its circulating molecular form and exact concentrations in human health/diseases are not known. Blue native-polyacrylamide gel electrophoresis of human serum was used to confirm the native conformation of α-macroglobulin. We created an enzyme-linked immunosorbent assay suitable for quantifying its circulating molecular form and undertook a cross-sectional study to measure its serum levels in 248 patients with diabetes mellitus and 59 healthy volunteers. The predominant circulating molecular form of α-macroglobulin was the tetramer, whereas its dimer was detectable in patients with high serum levels of α-macroglobulin. The serum α-macroglobulin concentration was not associated with glycated hemoglobin or any other glycemic variable as evaluated from 48-h continuous glucose monitoring, but showed close correlation with left ventricular posterior wall thickness, carotid artery intima-media thickness, urinary albumin:creatinine ratio (ACR) and brachial-ankle pulse wave velocity (baPWV). Multivariate analysis revealed only the ACR and baPWV to be independent variables influencing serum levels of α-macroglobulin. Thus, an increased ACR and baPWV are associated with higher serum concentrations of α-macroglobulin, and the latter may contribute to the mechanism by which albuminuria increases the risk of developing cardiovascular diseases.
Topics: Biomarkers; Blood Glucose; Case-Control Studies; Cross-Sectional Studies; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Female; Follow-Up Studies; Glycated Hemoglobin; Humans; Japan; Male; Middle Aged; Pregnancy-Associated alpha 2-Macroglobulins; Prognosis
PubMed: 31506491
DOI: 10.1038/s41598-019-49144-7 -
BMC Medicine Mar 2023Pre-eclampsia (PE) is one of the leading causes of maternal and fetal morbidity/mortality during pregnancy, and alpha-2-macroglobulin (A2M) is associated with...
BACKGROUND
Pre-eclampsia (PE) is one of the leading causes of maternal and fetal morbidity/mortality during pregnancy, and alpha-2-macroglobulin (A2M) is associated with inflammatory signaling; however, the pathophysiological mechanism by which A2M is involved in PE development is not yet understood.
METHODS
Human placenta samples, serum, and corresponding clinical data of the participants were collected to study the pathophysiologic mechanism underlying PE. Pregnant Sprague-Dawley rats were intravenously injected with an adenovirus vector carrying A2M via the tail vein on gestational day (GD) 8.5. Human umbilical artery smooth muscle cells (HUASMCs), human umbilical vein endothelial cells (HUVECs), and HTR-8/SVneo cells were transfected with A2M-expressing adenovirus vectors.
RESULTS
In this study, we demonstrated that A2M levels were significantly increased in PE patient serum, uterine spiral arteries, and feto-placental vasculature. The A2M-overexpression rat model closely mimicked the characteristics of PE (i.e., hypertension in mid-to-late gestation, histological and ultrastructural signs of renal damage, proteinuria, and fetal growth restriction). Compared to the normal group, A2M overexpression significantly enhanced uterine artery vascular resistance and impaired uterine spiral artery remodeling in both pregnant women with early-onset PE and in pregnant rats. We found that A2M overexpression was positively associated with HUASMC proliferation and negatively correlated with cell apoptosis. In addition, the results demonstrated that transforming growth factor beta 1 (TGFβ1) signaling regulated the effects of A2M on vascular muscle cell proliferation described above. Meanwhile, A2M overexpression regressed rat placental vascularization and reduced the expression of angiogenesis-related genes. In addition, A2M overexpression reduced HUVEC migration, filopodia number/length, and tube formation. Furthermore, HIF-1α expression was positively related to A2M, and the secretion of sFLT-1 and PIGF of placental origin was closely related to PE during pregnancy or A2M overexpression in rats.
CONCLUSIONS
Our data showed that gestational A2M overexpression can be considered a contributing factor leading to PE, causing detective uterine spiral artery remodeling and aberrant placental vascularization.
Topics: Animals; Female; Humans; Pregnancy; Rats; Endothelial Cells; Macroglobulins; Placenta; Placenta Growth Factor; Pre-Eclampsia; Rats, Sprague-Dawley; Uterine Artery
PubMed: 36894970
DOI: 10.1186/s12916-023-02807-9 -
Cellular and Molecular Life Sciences :... Mar 2011The plasmin-antiplasmin system plays a key role in blood coagulation and fibrinolysis. Plasmin and α(2)-antiplasmin are primarily responsible for a controlled and... (Review)
Review
The plasmin-antiplasmin system plays a key role in blood coagulation and fibrinolysis. Plasmin and α(2)-antiplasmin are primarily responsible for a controlled and regulated dissolution of the fibrin polymers into soluble fragments. However, besides plasmin(ogen) and α(2)-antiplasmin the system contains a series of specific activators and inhibitors. The main physiological activators of plasminogen are tissue-type plasminogen activator, which is mainly involved in the dissolution of the fibrin polymers by plasmin, and urokinase-type plasminogen activator, which is primarily responsible for the generation of plasmin activity in the intercellular space. Both activators are multidomain serine proteases. Besides the main physiological inhibitor α(2)-antiplasmin, the plasmin-antiplasmin system is also regulated by the general protease inhibitor α(2)-macroglobulin, a member of the protease inhibitor I39 family. The activity of the plasminogen activators is primarily regulated by the plasminogen activator inhibitors 1 and 2, members of the serine protease inhibitor superfamily.
Topics: Antifibrinolytic Agents; Binding Sites; Blood Coagulation; Fibrinolysis; Humans; Models, Biological; Models, Molecular; Plasminogen; Plasminogen Activators; Plasminogen Inactivators; Protein Structure, Tertiary; Serine Proteases; Serine Proteinase Inhibitors; alpha-Macroglobulins
PubMed: 21136135
DOI: 10.1007/s00018-010-0566-5 -
European Journal of Biochemistry Dec 1983Poly(A)-rich RNA was isolated from the livers of acutely inflamed rats by extraction with guanidinium HCl and oligo(dT)-cellulose chromatography. After translation in a...
Poly(A)-rich RNA was isolated from the livers of acutely inflamed rats by extraction with guanidinium HCl and oligo(dT)-cellulose chromatography. After translation in a recticulocyte lysate and immunoprecipitation with a specific antiserum to alpha 2-macroglobulin a polypeptide with an apparent molecular weight of 162000 could be detected. The cell-free synthesis of alpha 2-macroglobulin was stimulated 8-fold by the addition of RNase inhibitor. Full-length alpha 2-macroglobulin polypeptide chains appeared after 35 min in the presence of 1.85 mM Mg2+ and 100 mM K+. A nucleotide number of about 5100 was estimated for alpha 2-macroglobulin by means of sucrose gradient centrifugation of poly(A)-rich RNA followed by translation in vitro and immunoprecipitation of alpha 2-macroglobulin. In normal liver alpha 2-macroglobulin mRNA represented about 0.0007% of total translatable RNA. Acute inflammation generated by intramuscular injection of turpentine led to a 66-fold increase in translatable alpha 2-macroglobulin mRNA after 18 h, followed by a rapid decrease. In accordance to the induction of alpha 2-macroglobulin mRNA serum concentrations of alpha 2-macroglobulin increased to about 2 mg/ml. Unlike alpha 2-macroglobulin mRNA serum alpha 2-macroglobulin levels remained unchanged up to 60 h.
Topics: Animals; Cell-Free System; Chemical Precipitation; Immunochemistry; Inflammation; Liver; Male; Poly A; Protein Biosynthesis; RNA, Messenger; Rats; Rats, Inbred Strains; Turpentine; alpha-Macroglobulins
PubMed: 6197304
DOI: 10.1111/j.1432-1033.1983.tb07823.x -
PloS One 2015Alpha-2-macroglobulin is an abundant secreted protein that is of particular interest because of its diverse ligand binding profile and multifunctional nature, which...
Alpha-2-macroglobulin is an abundant secreted protein that is of particular interest because of its diverse ligand binding profile and multifunctional nature, which includes roles as a protease inhibitor and as a molecular chaperone. The activities of alpha-2-macroglobulin are typically dependent on whether its conformation is native or transformed (i.e. adopts a more compact conformation after interactions with proteases or small nucleophiles), and are also influenced by dissociation of the native alpha-2-macroglobulin tetramer into stable dimers. Alpha-2-macroglobulin is predominately present as the native tetramer in vivo; once purified from human blood plasma, however, alpha-2-macroglobulin can undergo a number of conformational changes during storage, including transformation, aggregation or dissociation. We demonstrate that, particularly in the presence of sodium chloride or amine containing compounds, freezing and/or lyophilization of alpha-2-macroglobulin induces conformational changes with functional consequences. These conformational changes in alpha-2-macroglobulin are not always detected by standard native polyacrylamide gel electrophoresis, but can be measured using bisANS fluorescence assays. Increased surface hydrophobicity of alpha-2-macroglobulin, as assessed by bisANS fluorescence measurements, is accompanied by (i) reduced trypsin binding activity, (ii) increased chaperone activity, and (iii) increased binding to the surfaces of SH-SY5Y neurons, in part, via lipoprotein receptors. We show that sucrose (but not glycine) effectively protects native alpha-2-macroglobulin from denaturation during freezing and/or lyophilization, thereby providing a reproducible method for the handling and long-term storage of this protein.
Topics: Freeze Drying; Freezing; Glucose; Humans; Protein Conformation; Sodium Chloride; Sucrose; alpha-Macroglobulins
PubMed: 26103636
DOI: 10.1371/journal.pone.0130036 -
Journal of Biological Physics Mar 2023Myricetin (MYR) is a bioactive secondary metabolite found in plants that is recognized for its nutraceutical value and is an essential constituent of various foods and...
Myricetin (MYR) is a bioactive secondary metabolite found in plants that is recognized for its nutraceutical value and is an essential constituent of various foods and beverages. It is reported to exhibit a plethora of activities, including antioxidant, antimicrobial, antidiabetic, anticancer, and anti-inflammatory. Alpha-2-macroglobulin (α2M) is a major plasma anti-proteinase that can inhibit proteinases of both human and non-human origin, regardless of their specificity and catalytic mechanism. Here, we explored the interaction of MYR-α2M using various biochemical and biophysical techniques. It was found that the interaction of MYR brings subtle change in its anti-proteolytic potential and thereby alters its structure and function, as can be seen from absorbance and fluorescence spectroscopy. UV spectroscopy of α2M in presence of MYR indicated the occurrence of hyperchromism, suggesting complex formation. Fluorescence spectroscopy reveals that MYR reduces the fluorescence intensity of native α2M with a shift in the wavelength maxima. At 318.15 K, MYR binds to α2M with a binding constant of 2.4 × 10 M, which indicates significant binding. The ΔG value was found to be - 7.56 kcal mol at 298.15 K, suggesting the interaction to be spontaneous and thermodynamically favorable. The secondary structure of α2M does not involve any major change as was confirmed by CD analysis. The molecular docking indicates that Asp-146, Ser-172, Glu-174, and Tyr-180 were the key residues involved in α2M-MYR complex formation. This study contributes to our understanding of the function and mechanism of protein and flavonoid binding by providing a molecular basis of the interaction between MYR and α2M.
Topics: Humans; Pregnancy; Female; Molecular Docking Simulation; Pregnancy-Associated alpha 2-Macroglobulins; Spectrum Analysis; Flavonoids
PubMed: 36662317
DOI: 10.1007/s10867-022-09621-z