Research status of E3 ubiquitin ligase Smurf2 and related signaling pathways in glioma

Glioma is the tumor with the highest incidence in the brain,and it is eager to seek new and efiective treatment.The interaction of ubiquitination and deubiquitination regulates many cell activities in organisms,and participates in tumor occurrence,development,migration,invasion and other processes.This article summarized the progress of E3 ubiquitination ligase smad ubiquitination regulatory factor 2(Smurf2)and glioma-related signaling pathways to assist clinical diagnosis and treatment of glioma.

Pilose antler aqueous extract promotes the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells by stimulating the BMP-2/Smad1, 5/Runx2 signaling pathway

Peptides from Pilose antler aqueous extract(PAAE) have been shown to stimulate the proliferation and differentiation of bone marrow mesenchymal stem cells(BMSCs). However, the underlying molecular mechanisms are not well understood. Here, PAAE was isolated and purified to explore the molecular mechanisms underlying PAAE’s effects on BMSCs as well as its osteoprotective effects in ovariectomized rats. Our results showed that PAAE promoted proliferation and differentiation of BMSCs to become osteoblasts by enhancing ALP activity and increasing extracellular matrix mineralization. The trabecular microarchitecture of ovariectomized rats was also found to be protected by PAAE. Quantitative reverse transcription-polymerase chain reaction(Quantitative RT-PCR) results suggest that PAAE also increased the expression of osteogenic markers including, alkaline phosphatase(ALP), runt-related transcription factor 2(Runx2), osteocalcin(OCN), bone morphogenetic protein-2(BMP-2), and collagen I(COL-I). Immunoblotting results indicated that PAAE upregulated the levels of BMP-2 and Runx2 and was associated with Smad1/5 phosphorylation. PAAE A at the concentration of 200μg·mL^-1 showed the strongest effect on proliferation and osteogenic differentiation of BMSCs after 48 h. Using matrix-assisted laser desorption/ionization time of flight mass spectrometry(MALDI-TOF MS), we identified the molecular weight of PAAE A and found that it is less than 3000 Da and showed several significant peaks. In conclusion, PAAE activates the BMP-2/Smad1, 5/Runx2 pathway to induce osteoblastic differentiation and mineralization in BMSCs and can inhibit OVX-induced bone loss. These mechanisms are likely responsible for its therapeutic effect on postmenopausal osteoporosis.

Deamidation enables pathogenic SMAD6 variants to activate the BMP signaling pathway

The BMP signaling pathway plays a crucial role in regulating early embryonic development and tissue homeostasis.SMAD6 encodes a negative regulator of BMP,and rare variants of SMAD6 are recurrently found in individuals with birth defects.However,we observed that a subset of rare pathogenic variants of SMAD6 consistently exhibited positive regulatory effects instead of the initial negative effects on the BMP signaling pathway.We sought to determine whether these SMAD6 variants have common pathogenic mechanisms.Here,we showed that pathogenic SMAD6 variants accompanying this functional reversal exhibit similar increases in deamidation.Mechanistically,increased deamidation of SMAD6 variants promotes the accumulation of the BMP receptor BMPR1A and the formation of new complexes,both of which lead to BMP signaling pathway activation.Specifically,two residues,N262 and N404,in SMAD6 were identified as the crucial sites of deamidation,which was catalyzed primarily by glutamine-fructose-6-phosphate transaminase 2(GFPT2).Additionally,treatment of cells harboring SMAD6 variants with a deamidase inhibitor restored the inhibitory effect of SMAD6 on the BMP signaling pathway.Conversely,when wild-type SMAD6 was manually simulated to mimic the deamidated state,the reversed function of activating BMP signaling was reproduced.Taken together,these findings show that deamidation of SMAD6 plays a crucial role in the functional reversal of BMP signaling activity,which can be induced by a subset of various SMAD6 variants.Our study reveals a common pathogenic mechanism shared by these variants and provides a potential strategy for preventing birth defects through deamidation regulation,which might prevent the off-target effects of gene editing.

The role of Smad6 in immunity of the pearl oyster Pinctada fucata martensii

Inhibitory Smads(I-Smads),which belong to the Smad family and inhibit bone morphogenic protein 2(BMP2)signaling by a variety of mechanisms,can suppress innate immunity responses in vertebrates.However,there are no reports for the role of Smad6 in immunity in mollusks.In this study,we showed that Smad6 of the pearl oyster Pinctada fucata martensii was located in the Smad6 cluster of the phylogenetic tree;mRNA expression of Smad6 and Smad3 was up-regulated after lipopolysaccharide and polyinosinic:polycytidylic challenge;and transcript levels of Smad6 and Smad3 showed opposite patterns during wound healing.Under salinity stress,water inflow and outflow in the gills appear to be regulated by BMP2-Smads signals,and BMP2-Smads signaling may be closely related to the immune response.Our results indicate that Smad6 is involved in immunity,that it plays a positive role in the response to immune challenge and an inhibitory role during wound healing,and that Smad6 and Smad3 may work against each other.

Cytokine receptor-like factor 1(CRLF1)promotes cardiac fibrosis via ERK1/2 signaling pathway

Cardiac fibrosis is a cause of morbidity and mortality in people with heart disease.Anti-fibrosis treatment is a significant therapy for heart disease,but there is still no thorough understanding of fibrotic mechanisms.This study was carried out to ascertain the functions of cytokine receptor-like factor 1(CRLF1)in cardiac fibrosis and clarify its regulatory mechanisms.We found that CRLF1 was expressed predominantly in cardiac fibroblasts.Its expression was up-regulated not only in a mouse heart fibrotic model induced by myocardial infarction,but also in mouse and human cardiac fibroblasts provoked by transforming growth factor-β1(TGF-β1).Gain-and loss-of-function experiments of CRLF1 were carried out in neonatal mice cardiac fibroblasts(NMCFs)with or without TGF-β1 stimulation.CRLF1 overexpression increased cell viability,collagen production,cell proliferation capacity,and myofibroblast transformation of NMCFs with or without TGF-β1 stimulation,while silencing of CRLF1 had the opposite effects.An inhibitor of the extracellular signal-regulated kinase 1/2(ERK1/2)signaling pathway and different inhibitors of TGF-β1 signaling cascades,comprising mothers against decapentaplegic homolog(SMAD)-dependent and SMAD-independent pathways,were applied to investigate the mechanisms involved.CRLF1 exerted its functions by activating the ERK1/2 signaling pathway.Furthermore,the SMAD-dependent pathway,not the SMAD-independent pathway,was responsible for CRLF1 up-regulation in NMCFs treated with TGF-β1.In summary,activation of the TGF-β1/SMAD signaling pathway in cardiac fibrosis increased CRLF1 expression.CRLF1 then aggravated cardiac fibrosis by activating the ERK1/2 signaling pathway.CRLF1 could become a novel potential target for intervention and remedy of cardiac fibrosis.

Xueshuantong for Injection(Lyophilized,注射用血栓通)Alleviates Streptozotocin-Induced Diabetic Retinopathy in Rats

Objective To investigate the ameliorate effect and underlying mechanism of Xueshuantong for Injection(Lyophilized,注射用血栓通,XST)in streptozocin(STZ)-induced diabetic retinopathy(DR)rats.Methods Diabetes mellitus(DM)model was induced by intraperitoneal(i.p.)injection of STZ(60 mg/kg)in Sprague-Dawley rats.Diabetic rats were randomized into 3 groups(n=10)according to a random number table,including DM,XST50 and XST100 groups.XST treatment groups were daily i.p.injected with 50 or 100 mg/kg XST for 60 days,respectively.The control and DM groups were given i.p.injection with saline.Blood glucose level and body weight were recorded every week.Histological changes in the retina tissues were observed with hematoxylin-eosin staining.Apoptosis and inflammation related factors,including cleaved caspase-3,glial fifibrillary acidic protein(GFAP),tumor necrosis factor-α(TNF-α)and intercellular cell adhesion molecule-1(ICAM-1)were detected by Western blot or real-time polymerase chain reaction.Then,the levels of advanced glycation end product(AGE)and its receptor(RAGE)were investigated.Tight junctions proteins(Zonula occludens-1(ZO-1),Occludin and Claudin-5)of blood-retinal barrier were detected by Western blot.The levels of retinal fifibrosis,transforming growth factor-β1(TGF-β1)-Smad2/3 signaling pathway were evaluated at last.Results There was no signifificant difference in the body weight and blood glucose level between XST and DM groups(P>0.05).Compared with the DM group,XST treatment signifificantly increased the retinal thickness of rats(P<0.05 or P<0.01),and suppressed cleaved caspase-3 expression(P<0.01).XST increased the protein expressions of ZO-1,Occludin and Claudin-5 and decreased the mRNA expressions of matrix metalloproteinase 2(MMP-2)and MMP-9(P<0.05 or P<0.01).Moreover,XST signifificantly reduced the productions of AGE and RAGE proteins in the retina of rats(P<0.05 or P<0.01),suppressed the over-expression of TNF-α,and decreased the elevated level of ICAM-1 in retina of rats(P<0.05 or P<0.01).XST signifificantly reduced the levels ofα-smooth muscle actin(α-SMA),connective tissue growth factor(CTGF),TGF-β1 and phosphorylation of Smad2/3 protein in rats(P<0.05 or P<0.01).Conclusions XST had protective effects on DR with possible mechanisms of inhibiting the inflammation and apoptosis,up-regulating the expression of tight junction proteins,suppressing the productions of AGE and RAGE proteins,and blocking the TGF-β/Smad2/3 signaling pathway.XST treatment might play a role for the future therapeutic strategy against DR.