ABSTRACT
Growth differentiation factor 15 (GDF-15) is a member of the transforming growth factor-β superfamily. It is widely distributed in the central and peripheral nervous systems. Whether and how GDF-15 modulates nociceptive signaling remains unclear. Behaviorally, we found that peripheral GDF-15 significantly elevated nociceptive response thresholds to mechanical and thermal stimuli in naïve and arthritic rats. Electrophysiologically, we demonstrated that GDF-15 decreased the excitability of small-diameter dorsal root ganglia (DRG) neurons. Furthermore, GDF-15 concentration-dependently suppressed tetrodotoxin-resistant sodium channel Nav1.8 currents, and shifted the steady-state inactivation curves of Nav1.8 in a hyperpolarizing direction. GDF-15 also reduced window currents and slowed down the recovery rate of Nav1.8 channels, suggesting that GDF-15 accelerated inactivation and slowed recovery of the channel. Immunohistochemistry results showed that activin receptor-like kinase-2 (ALK2) was widely expressed in DRG medium- and small-diameter neurons, and some of them were Nav1.8-positive. Blockade of ALK2 prevented the GDF-15-induced inhibition of Nav1.8 currents and nociceptive behaviors. Inhibition of PKA and ERK, but not PKC, blocked the inhibitory effect of GDF-15 on Nav1.8 currents. These results suggest a functional link between GDF-15 and Nav1.8 in DRG neurons via ALK2 receptors and PKA associated with MEK/ERK, which mediate the peripheral analgesia of GDF-15.
Subject(s)
Animals , Rats , Analgesia , Ganglia, Spinal , Growth Differentiation Factor 15 , Sensory Receptor Cells , Sodium Channels , Tetrodotoxin/pharmacologyABSTRACT
Growth differentiation factor 15 (GDF-15) is a member of the transforming growth factor-β superfamily. It is widely distributed in the central and peripheral nervous systems. Whether and how GDF-15 modulates nociceptive signaling remains unclear. Behaviorally, we found that peripheral GDF-15 significantly elevated nociceptive response thresholds to mechanical and thermal stimuli in naïve and arthritic rats. Electrophysiologically, we demonstrated that GDF-15 decreased the excitability of small-diameter dorsal root ganglia (DRG) neurons. Furthermore, GDF-15 concentration-dependently suppressed tetrodotoxin-resistant sodium channel Nav1.8 currents, and shifted the steady-state inactivation curves of Nav1.8 in a hyperpolarizing direction. GDF-15 also reduced window currents and slowed down the recovery rate of Nav1.8 channels, suggesting that GDF-15 accelerated inactivation and slowed recovery of the channel. Immunohistochemistry results showed that activin receptor-like kinase-2 (ALK2) was widely expressed in DRG medium- and small-diameter neurons, and some of them were Nav1.8-positive. Blockade of ALK2 prevented the GDF-15-induced inhibition of Nav1.8 currents and nociceptive behaviors. Inhibition of PKA and ERK, but not PKC, blocked the inhibitory effect of GDF-15 on Nav1.8 currents. These results suggest a functional link between GDF-15 and Nav1.8 in DRG neurons via ALK2 receptors and PKA associated with MEK/ERK, which mediate the peripheral analgesia of GDF-15.
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@#AIM: To investigate the expression of different kinds of transforming growth factors beta- 1(TGF- β1)and changes of activin receptor-like kinase(ALK)in pterygium and normal conjunctiva tissues. <p>METHODS: A total of 40 cases(40 eyes)of pterygium patients who underwent surgical treatment in our hospital were selected. In the same period, 40 cases(40 eyes)of normal conjunctiva tissues removed from the eye due to cataract surgery were selected. The expression of TGF-β1 receptors(ALK1/ALK5)in pterygium and normal conjunctiva tissues was detected by immunohistochemistry, with the proportion of positive staining cells counted. The expression of ALK1 and ALK5 mRNA and their proteins were quantified by reverse transcription polymerase chain reaction(RT-PCR)and Western Blot, respectively.<p>RESULTS: According to immunohistochemistry results, the ALK1 expression level was increased more distinct in pterygium group, compared to the normal conjunctiva group, and it was detected throughout the full-thickness pterygium epithelial cells, while only in the basal layer of epithelial cells in normal conjunctiva tissues; the ALK5 was detected in the basal layer of epithelial cells in both groups, while its level was decreased in the pterygium group compared to normal conjunctiva group. There was significant difference in the proportion of ALK1 and ALK5 positive cells between the two groups(all <i>P</i><0.05). The expression of the ALK1 mRNA and its protein in the pterygium tissues were significantly elevated, while the ALK5 mRNA level and its protein was significantly decreased, compared with the normal conjunctival group(<i>P</i><0.05).<p>CONCLUSION: Compared with the normal conjunctiva tissues, the expression of ALK1 and ALK5 in pterygium tissues was increased and decreased, respectively. This indicated different activation status of TGF-β signaling pathway, providing experimental evidence for further study on the pathogenesis of pterygium.
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OBJECTIVES: Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal dominant genetic disorder characterized by pathogenic blood vessel development and maintenance. HHT type 1 (HHT1) and type 2 (HHT2) are caused by variants in endoglin (ENG) and activin receptor-like kinase-1 (ACVRL1), respectively. The aim of this study was to identify the spectrum of pathogenic variants in ENG and ACVRL1 in Austrian HHT families. METHODS: In this prospective study, eight Austrian HHT families were screened for variants in ENG and ACVRL1 by polymerase chain reaction amplification and sequencing of DNA isolated from peripheral blood. RESULTS: Heterozygous variants were identified in all families under study. HHT1 was caused by a novel c.816+1G>A splice donor variant, a novel c.1479C>A nonsense (p.Cys493X) variant and a published c.1306C>T nonsense (p.Gln436X) variant in ENG. Variants found in ACVRL1 were novel c.200G>C (p.Arg67Pro) and known c.772G>A (p.Gly258Ser) missense variants in highly conserved residues, a known heterozygous c.100dupT frameshift (p.Cys34Leufs*4) and the known c.1204G>A missense (p.Gly402Ser) and c.1435C>T nonsense (p.Arg479X) variants as causes of HHT2. CONCLUSION: Novel and published variants in ENG (37.5%) and ACVRL1 (62.5%) were exclusively identified as the cause of HHT in an Austrian patient cohort. Identification of novel causative genetics variants should facilitate the development of tailored therapeutical applications in the future treatment of autosomal dominant HHT.
Subject(s)
Humans , Activins , Blood Vessels , Cohort Studies , DNA , Genetics , Polymerase Chain Reaction , Prospective Studies , Telangiectasia, Hereditary Hemorrhagic , Telangiectasis , Tissue DonorsABSTRACT
Activin receptor-like kinase (ALK) 1 is a transforming growth factor-β/bone morphogenetic pro-teins superfamily type Ⅰ receptor, predominantly expressed in active endothelial cells. ALK1 has been shown to play a piv-otal role in regulating angiogenesis, which is involved in vascular formation during embryonic and early postnatal develop-ment and angiogenesis-related diseases, such as cardiovascular disorders and tumor. Understanding the exact function of ALK1 in angiogenesis will provide theoretical basis for anti-angiogenic strategy of ALK1 inhibition. In the present study, we briefly recapitulate ALK1 signaling pathway and its role in blood vessel formation and pathological neovascularization.
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Objective To evaluate the effects of capparis spinosa total alkaloid on transforming growth factor-β( TGF-β)/Smad4 signalling pathways in systemic sclerosis (SSc). Methods A total of 90 BALB/c mice were randomly divided into normal control group, model control group, penicillamine ( 125 mg·kg-1) group and Capparis spinosa total alkaloid low (225 mg·kg-1),medium (450 mg·kg-1) and high ( 900 mg·kg-1) dose group. Except for the normal control group,SSc mouse model was established by daily subcutaneous injection of bleomycin in the back of the mice.After the establishment of the model,Capparis spinosa total alkaloid emulsifiable paste was externally applied to Capparis spinosa total alkaloid group,ground substance was externally applied to the mice in normal control group and model control groups, and penicillamine was intragastrically administrated in the penicillamine group for 60 days,once daily.After the treatment,The expression of TGF-β1in skin tissue was detected by Western-blotting and the levels of actin / in receptor-like kinase / Smad4, nuclear factor-κB in skin tissue were measured by ELISA. Results The expression of TGF-β1was significantly decreased after administration of 225,450 and 900 mg·kg-1capparis spinosa total alkaloid, and the levels of ALK1 and Smad4 were significantly decreased after administration of 900 mg·kg-1capparis spinosa total alkaloid as compared with model control group (P<0.05 or P<0.01),but the content of NF-κB was not influenced (P>0.05). Conclusion Capparis spinosa total alkaloid can accommodate abnormal expression of TGF-β1/Smad4 signalling pathways in SSc.
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OBJECTIVE To establish an in vitro screening system for activin receptor-like kinase 4,5 and 7 (ALK4,ALK5 and ALK7) inhibitors.METHODS The insect expression systems for kinase domain of ALK4,5,7 and Smad2/3 proteins were established using the Bac to Bac baculovirus expression system.The desired proteins were expressed in Sf9 insect cells and purified by GST affinity.The screening system was composed of the kinase,Smad3 protein,ATP as well as the compound.The impact of the compound on the activities of ALK kinase domains was examined by measuring the amount of remnant ATP in the system as ALKs catalyzed the phosphorylation of Smad3 protein and consumed ATP during the process.The screening conditions were optimized,and validation of the screening system was conducted using known ALKs inhibitors.RESULTS All the reconstructed Bacmids were identified to be correct by PCR and restriction enzyme digestion.All the proteins were expressed in Sf9 insect cells after transfection,and purified proteins were achieved by GST affinity purification.For the screening system,the optimized kinase concentration and Smad3 concentration were 10 mg· L-1 and the optimized ATP concentration was 10 nmol·L-1.The Z'factor for ALK4,ALK5,and ALK7 kinase inhibitors screening system was 0.71,0.51 and 0.74,respectively.The well-known ALK inhibitor SB431542 inhibited the catalytic activities of ALK4,ALK5,and ALK7 with IC50 values of 22,188 and 91 nmol· L-1,respectively.CONCLUSION The in vitro screening system for ALK4,ALK5 and ALK7 inhibitors is successfully established.
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OBJECTIVE To investigate the effect of tranilast on cardiac fibroblasts proliferation and phenotype transformation incubated with a high concentration of glucose and the possible mechanism. METHODS The cardiac fibroblasts were divided into seven groups in accordance with different nutrient solutions:normal control group(5.5 mmol · L-1 glucose),hypertonic group(5.5 mmol · L-1 glucose+mannitol 25 mmol · L- 1),high glucose group (25 mmol · L- 1 glucose),tranilast intervention groups (25 mmol·L-1 glucose+tranilast 50,100 and 200μmol·L-1),and activin receptor-like kinase 7(ALK7) inhibitor group(25 mmol · L-1 glucose+10μmol · L-1 SB431542). The cell proliferation was detected by MTT method. The transformation of cardiac fibroblasts was determined by immunfluorescence staining. The expression of fibroblast specific protein 1 (FSP-1),α-smooth muscle actin (α-SMA),transforming growth factor-β1(TGF-β1)and ALK7 was assessed by Western blotting. RESULTS Compared with nor?mal control group,A492 nm of cells in high glucose group was significantly increased(P<0.01),while the expression of α-SMA,TGF-β1 and ALK7 protein in high glucose group was significantly increased(P<0.01),but FSP-1 protein was significantly decreased(P<0.01). There was no difference between normal control group and hypertonic group. Compared with high glucose group,A492 nm of cells in tranilast or SB431542 intervention groups were decreased(P<0.05),and the expression of α-SMA,TGF-β1 and ALK7 protein was significantly decreased(P<0.05),but the expression of FSP-1 protein was increased (P<0.05)in tranilast or SB431542 intervention groups. CONCLUSION Tranilast can inhibit the proliferation and phenotype transformation of cardiac fibroblasts induced by high glucose,which may be related to down-regulation of the expression of ALK7.