ABSTRACT
BACKGROUND: Overexpression of tumor-associated growth arrest-specific protein 6 (Gas6) is found in many tumor entities. The prognostic value of Gas6 in renal cell carcinoma (RCC), especially in non-clear cell RCC, is still unclear. AIM: The aim of the study was to evaluate the prognostic impact of Gas6 expression in a large cohort of patients with chromophobe RCC (chRCC). MATERIAL AND METHODS: Patients who underwent renal surgery due to chRCC were retrospectively evaluated. Tumor specimens were analyzed for Gas6 expression by immunohistochemistry. RESULTS: Eighty-one chRCC patients were eligible for analysis; of these, 24 (29.6%) patients were positive for Gas6. No significant associations were found for Gas6 expression and clinical attributes in patients with chRCC. The Kaplan-Meier analysis revealed no differences in 5-year overall survival for Gas6- compared to Gas6+ (89.6% vs. 100.0%; p = 0.288) tumors. CONCLUSION: In chRCC, Gas6 expression is not associated with survival and other parameters of aggressiveness. Due to the rare incidence of chRCC, further studies with larger cohorts are warranted.
Subject(s)
Carcinoma, Renal Cell , Intercellular Signaling Peptides and Proteins , Kidney Neoplasms , Carcinoma, Renal Cell/pathology , Humans , Immunohistochemistry , Kidney Neoplasms/pathology , Prognosis , Retrospective StudiesABSTRACT
Inhalation of crystalline silica (CS) can cause silicosis, which is one of the most serious interstitial lung diseases worldwide. Autophagy dysfunction is an essential step in silicosis progression. In this study, we aim to identify the effect of growth arrest-specific protein 6 (Gas6) during autophagy induction and macrophage inflammatory response caused by CS. After RAW 264.7 macrophages exposed to CS, the levels of Gas6 and autophagy markers (p62, Beclin1, and LC3-II/LC3-I) were increased, accompanied with enhanced inflammatory cytokines secretion. Using autophagy activator (rapamycin) repressed, whereas autophagy inhibitor (3-methyladenine) promoted inflammatory cytokines release. Besides, inhibition of Gas6 aggravated CS-induced inflammatory response, and autophagy inhibition facilitated the promoted effect of Gas6 silencing, resulting in elevated expression of inflammatory cytokines. These findings reveal the protective effects of Gas6 and autophagy in macrophages in response to CS exposure, and highlight the autophagy regulated by Gas6 may be a potential prevention target for CS-induced lung inflammatory response.
Subject(s)
Silicon Dioxide , Silicosis , Autophagy , Cytokines/metabolism , Humans , Intercellular Signaling Peptides and Proteins , Macrophages , Silicon Dioxide/toxicity , Silicosis/metabolismABSTRACT
CONTEXT: Ginsenoside Rb1 (Rb1) exerts many beneficial effects and protects against cardiovascular disease. OBJECTIVE: To investigate whether Rb1 could attenuate age-related vascular impairment and identify the mechanism. MATERIALS AND METHODS: Female C57BL/6J mice aged 2 and 18 months, randomly assigned to Young, Young + 20 mg/kg Rb1, Old + vehicle, Old + 10 mg/kg Rb1 and Old + 20 mg/kg Rb1 groups, were daily intraperitoneal injected with vehicle or Rb1 for 3 months. The thoracic aorta segments were used to inspect the endothelium-dependent vasorelaxation. Left thoracic aorta tissues were collected for histological or molecular expression analyses, including ageing-related proteins, markers relevant to calcification and fibrosis, and expression of Gas6/Axl. RESULTS: We found that in Old + vehicle group, the expression of senescence proteins and cellular adhesion molecules were significantly increased, with worse endothelium-dependent thoracic aorta relaxation (58.35% ± 2.50%) than in Young group (88.84% ± 1.20%). However, Rb1 treatment significantly decreased the expression levels of these proteins and preserved endothelium-dependent relaxation in aged mice. Moreover, Rb1 treatment also reduced calcium deposition, collagen deposition, and the protein expression levels of collagen I and collagen III in aged mice. Furthermore, we found that the downregulation of Gas6 protein expression by 41.72% and mRNA expression by 52.73% in aged mice compared with young mice was abrogated by Rb1 treatment. But there was no significant difference on Axl expression among the groups. CONCLUSIONS: Our study confirms that Rb1 could ameliorate vascular injury, suggesting that Rb1 might be a potential anti-ageing related vascular impairment agent.
Subject(s)
Aging/drug effects , Ginsenosides/pharmacology , Intercellular Signaling Peptides and Proteins/genetics , Vascular Diseases/prevention & control , Age Factors , Aging/pathology , Animals , Aorta, Thoracic/drug effects , Aorta, Thoracic/metabolism , Dose-Response Relationship, Drug , Endothelium, Vascular/drug effects , Endothelium, Vascular/metabolism , Female , Gene Expression Regulation/drug effects , Ginsenosides/administration & dosage , Mice , Mice, Inbred C57BL , RNA, Messenger/metabolism , Vasodilation/drug effectsABSTRACT
OBJECTIVE: To investigate the role of growth arrest-specific protein 6 (Gas6) in the process of the migration and osteogenic differentiation of human periodontal ligament cells (hPDLCs). METHODS: After different concentrations of recombinant human Gas6 (rhGas6) were added to hPDLCs, cell prolife-ration experiment (CCK-8) was taken to observe the effect of rhGas6 on hPDLCs cell proliferation. Scratch test and cell migration test (Transwell) were taken to analyze the migratory ability of hPDLCs in different concentrations of rhGas6 groups. After osteogenic induction, real-time quantitative polymerase chain reaction (real-time PCR) was taken to detect the expression of the Runt-related transcription factor 2 (Runx2) and alkaline phosphatase (ALP). ALP staining was used to detect the amount of mineralized nodules. RESULTS: After adding different concentrations of rhGas6, there were no statistically significant differences in hPDLCs cell proliferation among the experimental groups and the control group at 24, 48 and 72 hours (P>0.05). After 24 h of scratch, the healing area in the 800 µg/L of the rhGas6 group was greater than that in the control group, but without statistically significant difference (31.06%±13.70% vs. 21.79%±9.51%, P>0.05). In the migration test, after 24 h, the number of hPDLCs cells which penetrated through the membrane in the 800 µg/L rhGas6 group was significantly higher than that in the control group (P < 0.01). After rhGas6 was added and osteogenic induction, Runx2 and ALP gene expressions of hPDLCs in the 800 µg/L group were significantly higher than those in the control group (1.60±0.30 vs. 0.91±0.10, 2.81±0.61 vs. 0.86±0.12, P < 0.01). After Gas6 was knocked down, the ALP expression of hPDLCs was significantly lower than that of the control group (0.39±0.07 vs. 0.92±0.14, P < 0.01). There was no significant change in Runx2 expression (P>0.05). After 7 days of osteogenic induction, the mineralized nodules formed in the Gas6 knockdown group were significantly less than those in control group (0.25±0.04 vs. 1.00±0.11, P < 0.001). After 14 days of induction, the staining degree of the Gas6 knockdown group was lower than that of the control group, but there was no significant difference (0.86±0.04 vs. 1.00±0.16, P>0.05). CONCLUSION: After downregulation of Gas6 gene, mineralized nodule formation was reduced and ALP gene expressions were decreased in the early stage of osteogenic induction (7 days). After addition of rhGas6, Runx2 and ALP gene expressions were increased and the number of cell migration was increased, suggesting that Gas6 might play a promoting role in the migration and osteogenic differentiation of human periodontal ligament cells.
Subject(s)
Osteogenesis , Periodontal Ligament , Alkaline Phosphatase , Cell Differentiation , Cell Proliferation , Cells, Cultured , Humans , Intercellular Signaling Peptides and ProteinsABSTRACT
OBJECTIVE: The purpose of this study is to determine whether TAM receptors and ligands associated with the activity and severity of lupus nephritis. METHODS: Clinical data were statistically analysed and studied in 122 SLE patients, diagnosed from 2013 to 2016 in First Hospital Affiliated to Harbin Medical University. Levels of TAM receptors and ligands in the plasma of 122 SLE patients were measured by ELISA. Renal biopsies were performed to confirm lupus nephritis (LN) by histopathology in 68 patients. The associations of TAM receptors and ligands with clinical and serological parameters were analysed in 68 LN patients. RESULTS: Amongst patients with SLE, those with LN had significantly higher plasma sMer, sAxl and GAS6 levels than those without renal involvement (P < 0.01 for all comparisons). Additional comparisons on the renal function-associated clinical parameters confirmed an indicative role of the sMer, sAXL and GAS6 levels in the cohort of patients with more severe nephritis. Patients with higher sMer, sAXL and GAS6 levels of LN patients tended to suffer from proliferative glomerulonephritis. The sAXL and GAS6 levels had a strong positive correlation with activity index (AI) in LN patients. Furthermore, there was a significant drop of the sMer, sAXL and GAS6 concentrations from the time of the biopsy to month t6, but no further decrease from months t6 to t12. CONCLUSIONS: These results suggest that plasma sMer, sAxl and GAS6 can be an additional clinical marker related to the disease activity and severity in LN.
Subject(s)
Intercellular Signaling Peptides and Proteins/metabolism , Lupus Nephritis/blood , Proto-Oncogene Proteins/metabolism , Receptor Protein-Tyrosine Kinases/metabolism , c-Mer Tyrosine Kinase/metabolism , Adolescent , Adult , Aged , Biomarkers/metabolism , Child , Cohort Studies , Enzyme-Linked Immunosorbent Assay , Female , Follow-Up Studies , Humans , Lupus Nephritis/pathology , Male , Middle Aged , ROC Curve , Young Adult , Axl Receptor Tyrosine KinaseABSTRACT
BACKGROUND AND PURPOSE: Ischemic stroke activates Toll-like receptors (TLRs), triggering rapid inflammatory cytokine production. Axl signaling has multiple roles, including regulating cytokine secretion, clearing apoptotic cells, and maintaining cell survival, however, its role in inflammation after ischemic stroke has not been examined. We hypothesized that activation of Axl by recombinant Growth-arrest-specific protein 6 (rGas6) attenuates neuroinflammation by inhibiting the TLR/TRAF/NF-κB pathway after middle cerebral artery occlusion (MCAO) in rats. METH: Sprague-Dawley rats were subjected to 2h of MCAO. One hour after reperfusion, the rats were given an intranasal injection of rGas6, vehicle, or R428 (Axl receptor inhibitor). Neurological scores, infarct volumes, immunofluorescence staining, Morris Water Maze, rotarod test and histology alterations were analyzed. The expressions of proinflammatory cytokines, including IL-1ß, IL-6, TNF-α, and Gas6, Axl, STAT1, SOCS1, SOCS3 and the TLR/TRAF/NF-κB pathway were quantified using Western blot. RESULTS: Endogenous expressions of Gas6 and Axl decreased significantly by 24h after MCAO. rGas6 reduced brain infarction and improved neurologic deficits scores, and increased expression of Axl and decreased the expressions of TRAF3, TRAF6 and inflammatory factors IL-1ß, IL-6, and TNF-α. Four weeks after MCAO, rGas6 improved long-term neurological behavior and memory. Inhibition of the Axl/TLR/TRAF/NF-κB pathway reversed the brain protection by rGas6. CONCLUSION: rGas6 reduced the neurological deficits by inhibiting neuroinflammation via the TLR/TRAF/NF-κB signaling pathway. rGas6 can be used as potential treatment to ischemic stroke.
Subject(s)
Brain/drug effects , Infarction, Middle Cerebral Artery/pathology , Intercellular Signaling Peptides and Proteins/pharmacology , Neuroprotective Agents/pharmacology , Receptor Protein-Tyrosine Kinases/metabolism , Animals , Anti-Inflammatory Agents/pharmacology , Brain/metabolism , Brain/pathology , Enzyme Activation/drug effects , Infarction, Middle Cerebral Artery/metabolism , Inflammation/metabolism , Inflammation/pathology , Intercellular Signaling Peptides and Proteins/metabolism , Male , NF-kappa B/metabolism , Rats , Rats, Sprague-Dawley , Recombinant Proteins/metabolism , Recombinant Proteins/pharmacology , Signal Transduction/drug effects , Signal Transduction/physiology , Toll-Like Receptors/metabolism , Tumor Necrosis Factor Receptor-Associated Peptides and Proteins/metabolismABSTRACT
Subclinical vitamin K deficits refer to carboxylation defects of different types of vitamin K-dependent hepatic and extrahepatic so-called Gla proteins without prolongation of the prothrombin time. This condition has been reported in different clinical situations due to insufficient supply or malabsorption of vitamin K as well as drug interactions. This review discusses the effects of different vitamin K subspecies on tumour growth and the possible anti-tumour effects of increased vitamin K intake. Blocking carboxylation of vitamin K-dependent proteins with warfarin anticoagulation - what are the risks/benefits for carcinogenesis? Previous studies on both heparin and low molecular weight heparin blocking of the vitamin K-dependent factors X and II have shown tumour suppressive effects. Vitamin K has anti-inflammatory effects that could also impact carcinogenesis, but little data exists on this subject.
Subject(s)
Carcinogenesis/metabolism , Vitamin K/physiology , Animals , Cell Proliferation , Humans , Neoplasms/etiology , Neoplasms/metabolism , Neoplasms/pathology , Risk Factors , Vitamin K Deficiency/complications , Vitamin K Deficiency/metabolismABSTRACT
AXL is the gene that encodes the Anexelekto (AXL) receptor tyrosine kinase that demonstrates significant roles in various cellular processes, including cell growth, survival, and migration. Anexelekto is a Greek word meaning excessive and uncontrolled, semantically implying the crucial involvement of AXL in cancer and immune biology, and in promoting cancer metastasis. AXL overexpression appears to drive epithelial to mesenchymal transition, tumor angiogenesis, decreased antitumor immune response, and resistance to therapeutic agents. Recently, AXL has been reported to play important roles in several viral infections, including SARS-CoV-2. We have previously outlined the importance of microRNAs (miRNAs, miRs) and especially miR-155 in SARS-CoV-2 pathophysiology through regulation of the Renin-Angiotensin Aldosterone System (RAAS) and influence on several aspects of host innate immunity. MiRNAs are negative regulators of gene expression, decreasing the stability of target RNAs or limiting their translation and, enthrallingly, miR-155 is also involved in AXL homeostasis-both endogenously and pharmaceutically using repurposed drugs (e.g., metformin)-highlighting thrifty evolutionary host innate immunity mechanisms that successfully can thwart viral entry and replication. Cancer, infections, and immune system disturbances will increasingly involve miRNA diagnostics and therapeutics in the future.
Subject(s)
COVID-19 , MicroRNAs , Neoplasms , Humans , SARS-CoV-2/metabolism , Axl Receptor Tyrosine Kinase , Proto-Oncogene Proteins/genetics , Epithelial-Mesenchymal Transition/genetics , COVID-19/genetics , MicroRNAs/geneticsABSTRACT
Objective: Growth arrest-specific protein 6 (Gas6) may harbor protective effects in acute brain injury. This study was designed to determine the relation of serum Gas6 levels to severity and prognosis after traumatic brain injury (TBI). Methods: In this prospective cohort study of 114 controls and 114 patients with severe TBI, multivariate analysis was used to assess relationships between serum Gas6 levels, Glasgow coma scale (GCS) score, Rotterdam computed tomography (CT) score, postinjury 180-day mortality, overall survival and poor prognosis (Extended Glasgow outcome scale score 1-4). Results: Significantly increased serum Gas6 levels of patients (median, 10.3 ng/mL versus 32.5 ng/mL; P < 0.001), as compared with controls, were independently correlated with Rotterdam CT score (t = 3.629, P < 0.001) and GCS score (t=-3.393, P = 0.001), and independently predicted 180-day mortality (odds ratio, 1.078; 95% confidence interval (CI), 1.007-1.154), overall survival (hazard ratio, 1.074; 95% CI, 1.012-1.139) and poor prognosis (odds ratio, 1.129; 95% CI, 1.059-1.205). Areas under receiver operating characteristic curve (AUCs) of serum Gas6 levels for discriminating risks of 180-day mortality and poor prognosis were 0.785 (95% CI, 0.699-0.857) and 0.793 (95% CI, 0.707-0.863), respectively; and serum Gas6 levels above 30.9 ng/mL and 28.3 ng/mL predicted 180-day mortality and poor prognosis with maximum Youden indices of 0.451 and 0.468, respectively. The predictive ability of serum Gas6 levels for mortality was similar to those of GCS score (AUC, 0.833; 95% CI, 0.751-0.896; P = 0.286) and Rotterdam CT score (AUC, 0.823; 95% CI, 0.740-0.888; P = 0.432). The discriminatory capability of serum Gas6 levels for the risk of poor prognosis was in the range of GCS score (AUC, 0.846; 95% CI, 0.766-0.906; P = 0.178) and Rotterdam CT score (AUC, 0.831; 95% CI, 0.750-0.895; P = 0.368). Conclusion: Serum Gas6 may appear as a promising biochemical parameter for aiding in the assessment of trauma severity and prediction of prognosis among patients with severe TBI.
ABSTRACT
BACKGROUND: Growth-arrest-specific protein 6 (Gas6) exerts nervous protective effects on acute brain injury. We endeavored to ascertain whether serum Gas6 concentrations are associated with severity, delayed cerebral ischemia (DCI) and prognosis following aneurysmal subarachnoid hemorrhage (aSAH). METHODS: We measured serum Gas6 concentrations of 124 aSAH patients. The Hunt-Hess scale and modified Fisher grading scale were used to evaluate illness severity. Multivariate analysis was utilized to determine relationships between serum Gas6 concentrations and severity, DCI plus 90-day unfavorable outcome (Glasgow outcome scale score of 1-3). RESULTS: Patients with unfavorable outcome or DCI had significantly higher serum Gas6 concentrations than other remainders (median, 35.0 vs 23.3 ng/ml; 36.1 vs 25.3 ng/ml; both P < 0.001). Serum Gas6 concentrations displayed independent correlations with Hunt-Hess scores (t = 5.518, P < 0.001) and modified Fisher scores (t = 3.531, P = 0.001). Serum Gas6 concentrations were independently associated with unfavorable outcome (OR: 1.125; 95% CI, 1.063-1.190; P = 0.014) and DCI (OR: 1.104; 95% CI, 1.041-1.170; P = 0.010) as well as exhibited AUCs of 0.786 (95% CI, 0.703-0.854) and 0.753 (95% CI, 0.668-0.826) for predicting unfavorable outcome and DCI respectively. Its discriminatory ability for risk of unfavorable outcome or DCI was similar to those of Hunt-Hess scores and modified Fisher scores (all P > 0.05). CONCLUSIONS: Serum Gas6 concentrations are independently associated with stroke severity and worse clinical outcome after aSAH, indicating serum Gas6 may be a potential prognostic biomarker for aSAH.
Subject(s)
Brain Ischemia , Stroke , Subarachnoid Hemorrhage , Cerebral Infarction , Humans , Prospective Studies , Stroke/complicationsABSTRACT
Several studies have demonstrated that growth arrest-specific protein 6 (Gas6) and Axl are highly expressed in various tumor tissues, such as renal cell and esophageal carcinoma. However, the effect of the Gas6/Axl signaling pathway on lung adenocarcinoma is still unclear. The aim of the present study was to investigate the effect of the Gas6/Axl signaling pathway on lung adenocarcinoma cells and its mechanism of action, which may provide a novel target for the clinical treatment of lung adenocarcinoma. Human lung adenocarcinoma tissues were used to examine the activation of the Gas6/Axl signaling pathway. In addition, the human lung adenocarcinoma cell line A549 was employed to study the effects of the Gas6/Axl signaling pathway on the proliferation, migration, invasion and apoptosis of lung adenocarcinoma cells. Recombinant human Gas6 protein and inhibitor TP-0903 were used to activate and inhibit the Gas6/Axl signaling pathway, respectively. The results revealed that Gas6 and Axl expression level was increased in human lung adenocarcinoma tissues compared with adjacent healthy tissues. After inhibition of the Gas6/Axl signaling pathway with TP-0903, p21, p53, caspase 3, caspase 8 and caspase 9 exhibited higher expression level in A549 cells. The opposite effect was observed when the Gas6/Axl signaling pathway was activated. In addition, the migratory and invasive ability of A549 cells was determined via wound-healing and Transwell invasion assays. The results indicated that the migratory and invasive ability of A549 cells was significantly increased when the Gas6/Axl signaling pathway was activated and inhibition of Gas6/Axl signaling pathway caused the opposite results. Activity of Gas6/Axl signaling pathway was shown to be positively associated with cell proliferation by Cell Counting Kit 8 and clone formation assays. In conclusion, the Gas6/Axl signaling pathway was revealed to promote the proliferation, migration and invasion and inhibit the apoptosis of lung adenocarcinoma cells, which serve important roles in the progression of lung adenocarcinoma.
ABSTRACT
Role of growth arrest-specific 6 (Gas6), member of vitamin K (VK)-dependent protein family in hyperlipidemia-associated inflammation remains unresolved. To address this, blood samples were collected from hyperlipidemic subjects and age-matched healthy controls and observed that gamma-glutamyl carboxylated Gas6 (Gla-Gas6) but not total Gas6 were significantly lower while pro-inflammatory markers, MCP-1 and ICAM-1 were remarkably higher in hyperlipidemic subjects compared to control. Correlation analyses demonstrated that Gla-Gas6 levels were inversely correlated with MCP-1 and ICAM-1 but positively with plasma VK in hyperlipidemic subjects but not in control. This suggests that boosting VK level might ameliorate the hyperlipidemia-associated inflammatory pathophysiology via augmenting Gla-Gas6. Further studies with high fat diet (HFD)-fed mice demonstrated that VK supplementation (1, 3, and 5 µg/kg BW, 8 weeks) dose-dependently reduced both hepatic and plasma levels of MCP-1 and ICAM-1 while elevating that of Gla-Gas6 but not total Gas6 in HFD-fed mice. Cell culture studies with gamma-glutamyl carboxylase (enzyme causes VK-dependent carboxylation of Gas6) knockdown hepatocytes and monocytes dissected the direct role of Gla-Gas6 in inhibiting high palmitic acid (0.75 mM)-induced inflammation via arresting MCP-1/ICAM-1 mediated hepatocyte-monocyte adhesion. The present study demonstrated an important role of Gla-Gas6 in facilitating the prophylactic effect of VK against hyperlipidemia associated inflammation.
Subject(s)
Chemokine CCL2/metabolism , Hyperlipidemias/complications , Inflammation/drug therapy , Intercellular Adhesion Molecule-1/metabolism , Intercellular Signaling Peptides and Proteins/metabolism , Vitamin K/pharmacology , Cell Adhesion/drug effects , Cell Adhesion/physiology , Chemokine CCL2/genetics , Chronic Disease , Gene Expression Regulation/drug effects , Hepatocytes/physiology , Humans , Inflammation/etiology , Intercellular Adhesion Molecule-1/genetics , Intercellular Signaling Peptides and Proteins/genetics , Monocytes/physiologyABSTRACT
Phosphatidylserine (PS) is an anionic phospholipid that is usually localized in the inner leaflets of the plasma membrane. However, the enzyme scramblase catalyzes the externalization of PS on the outer leaflet of the plasma membrane during apoptosis or cellular stress. This event prompts the recognition of PS displaying cells by phagocytes leading to "apoptotic clearance." Multiple PS receptors (PSRs) mediate this process including members from the TAM (Tyro3, Axl, Mertk) receptor Tyrosine kinases (RTKs) by interacting with PS via bridging proteins like Gas6 and ProS1. Ironically, this network (PS/TAM) that evolved for boosting cellular health through clearance of apoptotic and necrotic cells, has been manoeuvred by pathogens and tumor cells using "apoptotic mimicry." Enveloped viruses, responsible for most of the lethal epidemics and pandemics including the current SARS-CoV2 outbreak, have employed apoptotic mimicry to their advantage. In the current chapter, we summarize the existing knowledge regarding the involvement of PS/Gas6, ProS1/TAM in facilitating infectivity in a diverse set of cell lines, animals as well as organoids. This network executes a largely proviral role in facilitating infection as seen with Zika, Ebola, Influenza and Dengue viruses. However, this response varies with strains and the cells infected, and in some cases, this same signaling displays an antiviral function. We also report multiple studies that have used neutralizing antibodies and small molecule inhibitors in successfully reducing viral replication and ameliorating pathogenicity. Knowledge about this unique signaling pathway and measures that can be taken to inhibit it is most valuable now given how enveloped viruses lead to plagues on the entire globe.
Subject(s)
Proto-Oncogene Proteins/metabolism , RNA Virus Infections/metabolism , RNA Viruses/metabolism , Receptor Protein-Tyrosine Kinases/metabolism , Receptors, Cell Surface/metabolism , Signal Transduction , c-Mer Tyrosine Kinase/metabolism , Animals , Humans , Intercellular Signaling Peptides and Proteins/metabolism , Protein S/metabolism , Axl Receptor Tyrosine KinaseABSTRACT
PURPOSE: Growth arrest-specific protein 6 (Gas6) is a vitamin K-dependent protein that plays an important role in the pathogenesis of autoimmune diseases. The purpose of this study was to explore the expression of Gas6 and its effects on autoimmune thyroiditis (AIT). METHOD: A total of 24 male NOD.H-2h4 mice were randomly assigned to three groups: (1) a control group supplied with regular water; (2) a sodium iodide (NaI) group supplied with 0.005% sodium iodide water; and (3) a group treated with recombinant mouse Gas6 (rmGas6) after iodine supplementation (NaIâ¯+â¯Gas6 group). The severity of lymphocytic infiltration in the thyroid was measured through histopathology. Serum levels of tumor necrosis factor α (TNF-α), interleukin (IL) 6 and IL-1ß, as well as anti-thyroglobulin antibody (TgAb) titers were measured using an enzyme-linked immunosorbent assay. In addition, the expression of Gas6, Caspase 3, TAM receptors (Axl and MerTK), nuclear factor κB (NF-κB) and I-kappa-B α (IκB-α) were measured by Western blotting. Finally, the proportions of T cells were determined in the splenocytes of NOD.H-2h4 mice by flow cytometry. RESULTS: The mRNA and protein expression of Gas6 was significantly lower in the NaI group compared to the control group. Serum levels of TgAb, TNF-α, IL-6 and IL-1ß were also significantly higher in the NaI group but were dramatically reduced after rmGas6 injection. The prevalence of thyroiditis and the infiltration of lymphocytes were significantly lower in the NaIâ¯+â¯Gas6 group compared to the NaI group. The protein expression of cleaved-Caspase 3, phosphorylation of MerTK, and NF-κB and IκB-α in the thyroid gland were significantly reduced after rmGas6 administration. The proportion of Th1, Th2 and Th17 cells in splenocytes were also significantly reduced after rmGas6 treatment, whereas there was a dramatic increase in the proportion of Treg cells. CONCLUSION: Gas6 exerts an anti-inflammatory effect in a mouse model of AIT and may therefore be a potential therapeutic target.
Subject(s)
Intercellular Signaling Peptides and Proteins/immunology , Thyroiditis, Autoimmune/immunology , Animals , Apoptosis , Autoantibodies/blood , Cytokines/blood , Disease Models, Animal , Intercellular Signaling Peptides and Proteins/genetics , Intercellular Signaling Peptides and Proteins/pharmacology , Iodine , Male , Mice , Recombinant Proteins/pharmacology , Thyroid Gland/immunology , Thyroiditis, Autoimmune/bloodABSTRACT
BACKGROUND: Growth arrest-specific 6 (Gas6) is a vitamin K-dependent protein secreted by immune cells, endothelial cells, vascular smooth muscle cells, and adipocytes. Recent studies indicate that Gas6 and receptors of the TAM (Tyro3, Axl, and Mer) family may be involved in the pathogenesis of obesity, systemic inflammation, and insulin resistance. The aim of this study was to investigate the association between plasma Gas6 protein and the c.843 + 7G>A Gas6 polymorphism in metabolic syndrome (MetS). METHODS: Two hundred five adults (88 men and 117 women) were recruited in this study. Plasma Gas6 concentration, general, and biochemical data were measured. All subjects were genotyped for the c.843 + 7G>A Gas6 polymorphism. RESULTS: Plasma Gas6 concentrations decreased in parallel with various MetS components in all groups (P = 0.017 for trend). Patients in the second and third tertiles of Gas6 level had higher high-density lipoprotein cholesterol (HDL-C) levels than those in the first tertile overall and in the female group. Plasma Gas6 levels were significantly positively correlated with HDL-C level and negatively with fasting glucose level in the female patients. The A allele and genotype AA in single nucleotide polymorphism c.843 + 7G>A were less frequent in the subjects with MetS compared to those without MetS. CONCLUSIONS: Our results demonstrated a positive correlation between Gas6 protein values and HDL-C and reinforce the association with fasting glucose. In addition, the presence of c.843 + 7G>A Gas6 polymorphisms, especially the AA genotype, had an association with MetS. The potential role of the Gas6/TAM system in MetS deserves further investigation.
Subject(s)
Intercellular Signaling Peptides and Proteins/blood , Intercellular Signaling Peptides and Proteins/genetics , Metabolic Syndrome/blood , Metabolic Syndrome/genetics , Polymorphism, Single Nucleotide , Adult , Aged , Case-Control Studies , Female , Genetic Predisposition to Disease , Genotype , Humans , Male , Metabolic Syndrome/epidemiology , Middle Aged , Young AdultABSTRACT
Previously, we demonstrated that growth arrest-specific protein 6 (Gas6)/Axl or Mer signaling inhibited the transforming growth factor (TGF)-ß1-induced epithelial-mesenchymal transition (EMT) in lung epithelial cells. Hepatocyte growth factor (HGF) has also been shown to inhibit TGF-ß1-induced changes in EMT markers. Here, we examined whether Gas6 signaling can induce the production of HGF and c-Met in lung alveolar epithelial cells to mediate the inhibition of EMT and to inhibit the migration and invasion of epithelial cells. The inhibition of the RhoA/Rho kinase pathway, using either a RhoA-targeted small interfering RNA (siRNA) or the Rho kinase pharmacologic inhibitor Y27362, prevented the inhibition of TGF-ß1-induced EMT in LA-4 cells and primary alveolar type II (AT II) epithelial cells. The c-Met antagonist PHA-665752 also blocked the anti-EMT effects associated with Gas6. Moreover, treatment with Y27362 or PHA-665752 prevented the Gas6-mediated inhibition of TGF-ß1-induced migration and invasion. Our data provided evidence that the RhoA-dependent production of HGF and c-Met mediated the Gas6-induced inhibition of EMT, migration and invasion in lung alveolar epithelial cells. Thus, Gas6/Axl and Mer/RhoA signaling may be necessary for the maintenance of homeostasis in the alveolar epithelium, via HGF and c-Met.
Subject(s)
Alveolar Epithelial Cells/cytology , Hepatocyte Growth Factor/metabolism , Intercellular Signaling Peptides and Proteins/metabolism , Proto-Oncogene Proteins c-met/metabolism , rhoA GTP-Binding Protein/metabolism , Alveolar Epithelial Cells/metabolism , Amides/pharmacology , Animals , Cell Line , Cell Movement/drug effects , Epithelial-Mesenchymal Transition/drug effects , Homeostasis/drug effects , Humans , Indoles/pharmacology , Male , Mice , Mice, Inbred BALB C , Pyridines/pharmacology , RNA, Small Interfering/pharmacology , Signal Transduction , Sulfones/pharmacology , rhoA GTP-Binding Protein/geneticsABSTRACT
The present study for the first time aims to examine the hypothesis that circulating gamma-glutamyl carboxylated growth arrest specific protein 6 (Gla-Gas6) deficiency may be associated with hyperlipidemia and vitamin K (VK) supplementation may ameliorate the impaired lipid homeostasis via activating Gas6 protein. Subjects with hyperlipidemia (n=22) and age-matched healthy controls (n=19) were included in this study. Results showed that plasma levels of Gla-Gas6 protein and VK were significantly lower in hyperlipidemic subjects compared to control. Moreover, Gla-Gas6 levels were significantly and positively correlated with VK (P=.034, r=0.452) and negatively with triglyceride (P=.022, r=-0.485) and total cholesterol (P=.043, r=-0.435) in hyperlipidemic subjects, which suggest that VK supplementation may have a positive effect in activating Gas6 protein and thereby reducing the aberrant plasma lipid levels. Further studies with high-fat diet (HFD)-fed animal model of hyperlipidemia demonstrated that VK supplementation (5 µg/kg body weight, 8 weeks) reduced the plasma lipid levels, stimulated both the plasma levels and the hepatic protein expression of Gla-Gas6 protein, and regulated the AMPK/SREBP1/PPARα signaling pathways of hepatic lipid metabolism in HFD-fed mice. Moreover, by using palmitic acid (PA, 0.75 mM)-treated both control and GGCX knockdown hepatocytes, this study dissected the direct role of Gla-Gas6 in mediating the positive effect of VK on preventing the PA-induced impaired hepatic lipid metabolism via regulating AMPK/SREBP1/PPARα pathways. Combining all, the present study demonstrated the beneficial effect of VK supplementation in preventing the impaired lipid homeostasis via activating VK-dependent Gas6 protein.
Subject(s)
AMP-Activated Protein Kinases/metabolism , Intercellular Signaling Peptides and Proteins/metabolism , PPAR alpha/metabolism , Sterol Regulatory Element Binding Protein 1/metabolism , Vitamin K/metabolism , Animals , Cell Survival , Female , Hepatocytes/metabolism , Homeostasis , Humans , Hyperlipidemias/metabolism , Intercellular Signaling Peptides and Proteins/genetics , Lipid Metabolism , Male , Mice , Middle Aged , Palmitic Acid/metabolism , Signal Transduction , Triglycerides/metabolismABSTRACT
Essentials Signaling by Gas6 through Tyro3/Axl/Mer receptors is essential for stable platelet aggregation. UNC2025 is a small molecule inhibitor of the Mer tyrosine kinase. UNC2025 decreases platelet activation in vitro and thrombus formation in vivo. UNC2025's anti-platelet effect is synergistic with inhibition of the ADP receptor, P2Y12 . SUMMARY: Background Growth arrest-specific protein 6 signals through the TAM (TYRO-3-AXL-MERTK) receptor family, mediating platelet activation and thrombus formation via activation of the aggregate-stabilizing αIIb ß3 integrin. Objective To describe the antithrombotic effects mediated by UNC2025, a small-molecule MERTK tyrosine kinase inhibitor. Methods MERTK phosphorylation and downstream signaling were assessed by immunoblotting. Light transmission aggregometry, flow cytometry and microfluidic analysis were used to evaluate the impact of MERTK inhibition on platelet activation and stability of aggregates in vitro. The effects of MERTK inhibition on arterial and venous thrombosis, platelet accumulation at microvascular injury sites and tail bleeding times were determined with murine models. The effects of combined treatment with ADP-P2Y1&12 pathway antagonists and UNC2025 were also evaluated. Results and Conclusions Treatment with UNC2025 inhibited MERTK phosphorylation and downstream activation of AKT and SRC, decreased platelet activation, and protected animals from pulmonary embolism and arterial thrombosis without increasing bleeding times. The antiplatelet effect of UNC2025 was enhanced in combination with ADP-P2Y1&12 pathway antagonists, and a greater than additive effect was observed when these two agents with different mechanisms of inhibition were coadministered. TAM kinase signaling represents a potential therapeutic target, as inhibition of this axis, especially in combination with ADP-P2Y pathway antagonism, mediates decreased platelet activation, aggregate stability, and thrombus formation, with less hemorrhagic potential than current treatment strategies. The data presented here also demonstrate antithrombotic activity mediated by UNC2025, a novel translational agent, and support the development of TAM kinase inhibitors for clinical applications.
Subject(s)
Adenine/analogs & derivatives , Blood Platelets/drug effects , Piperazines/pharmacology , Platelet Activation/drug effects , Platelet Aggregation Inhibitors/pharmacology , Protein Kinase Inhibitors/pharmacology , Pulmonary Embolism/prevention & control , Thrombosis/prevention & control , c-Mer Tyrosine Kinase/antagonists & inhibitors , Adenine/pharmacokinetics , Adenine/pharmacology , Animals , Blood Platelets/enzymology , Disease Models, Animal , Drug Synergism , Drug Therapy, Combination , Female , Humans , Intercellular Signaling Peptides and Proteins/metabolism , Male , Mice, Inbred C57BL , Phosphorylation , Piperazines/pharmacokinetics , Platelet Aggregation/drug effects , Platelet Aggregation Inhibitors/pharmacokinetics , Platelet Glycoprotein GPIIb-IIIa Complex/metabolism , Protein Kinase Inhibitors/pharmacokinetics , Proto-Oncogene Proteins/metabolism , Pulmonary Embolism/blood , Pulmonary Embolism/enzymology , Purinergic P2Y Receptor Antagonists/pharmacology , Receptor Protein-Tyrosine Kinases/metabolism , Signal Transduction/drug effects , Thrombosis/blood , Thrombosis/enzymology , c-Mer Tyrosine Kinase/metabolism , Axl Receptor Tyrosine KinaseABSTRACT
AIM: Growth arrest specific protein 6 (Gas-6) and its tyrosine kinase receptor Axl plays an important role in apoptosis, and regulation of innate immune response, therefore, we investigated their plasma concentrations in Rheumatoid arthritis (RA) patients and correlated them to clinical, laboratory and radiological parameters of the disease. METHODS: Plasma from 77 RA patients and 50 normal healthy subjects were assayed for plasma Gas6 and Axl levels. Demographic, clinical and serological data were prospectively assessed. Rheumatoid arthritis disease activity was assessed using 28-joint Disease Activity Score (DAS-28) and functional capacity by modified health assessment questionnaire (mHAQ). Standardized x-rays for hands and feet were done to all participants. RESULTS: The level of Gas6 and Axl were significantly decreased in the RA patients compared to those of the healthy control subjects. Levels of Gas6 correlated positively with Axl levels in both patients and healthy control. Gas6 levels were remarkably reduced in those patients with erosive RA than those without. Levels of Gas6 were found to be negatively correlated with the presence of erosive disease and positively correlated with DAS-28, ESR, Leucocytosis and IL6. CONCLUSION: The plasma concentrations of Gas6 and Axl are altered in RA patients and thus may have a role in RA pathogenesis. Further mechanistic studies on the involvement of all TAM receptors tyrosine kinases pathway in RA are needed to help in understanding the pathogenesis and possibly aid in diagnosis and future treatments of RA especially for patients with erosive disease.
Subject(s)
Arthritis, Rheumatoid/blood , Intercellular Signaling Peptides and Proteins/blood , Proto-Oncogene Proteins/blood , Receptor Protein-Tyrosine Kinases/blood , Adult , Arthritis, Rheumatoid/diagnosis , Biomarkers/blood , Blood Sedimentation , Case-Control Studies , Cross-Sectional Studies , Disability Evaluation , Down-Regulation , Female , Humans , Interleukin-6/blood , Male , Middle Aged , Predictive Value of Tests , Prospective Studies , Severity of Illness Index , Surveys and Questionnaires , Axl Receptor Tyrosine KinaseABSTRACT
Growth arrest-specific protein 6 (Gas6) works synergistically with erythropoietin (EPO) to increase the proliferation and maturation of erythroblasts. However, the role of Gas 6 levels on EPO resistance in hemodialysis (HD) patients remains unclear. Therefore, the objective of this study was the first to examine the correlation between plasma Gas6 levels and EPO resistance in HD patients. We enrolled 134 HD patients and 85 healthy individuals. The HD patients were divided into 2 groups: 98 non-EPO-resistant patients and 36 EPO-resistant patients. Plasma levels of Gas6, interleukin 6 (IL-6), high-sensitivity C-reactive protein (hs-CRP), and albumin were quantified. Compared with non-EPO-resistant patients, EPO-resistant patients had elevated plasma concentrations of Gas6 (15.4 ± 3.3 vs. 13.7 ± 3.2 ng/mL, P = 0.006), IL-6 (3.1 ± 3.1 vs. 2.1 ± 1.5 pg/mL, P = 0.009), and hs-CRP (12.7 ± 25.2 vs. 4.5 ± 5.5 mg/L, P = 0.002). In EPO-resistant HD patients, plasma Gas6 levels were negatively correlated with albumin levels (r = -0.388, P < 0.021). Elevated Gas6 levels are associated with EPO resistance in HD patients. Also, EPO resistance is related to inflammation and malnutrition. Thus, circulating Gas6 levels could be used as the potential marker in HD patients with EPO resistance.