Structural classification of αββ and ββα supersecondary structure units in proteins

We present a fully automatic structural classification of supersecondary structure units, consisting of two hydrogen-bonded β strands, preceded or followed by an α helix. The classification is performed on the spatial arrangement of the secondary structure elements, irrespective of the length and conformation of the intervening loops. The similarity of the arrangements is estimated by a structure alignment procedure that uses as similarity measure the root mean square deviation of superimposed backbone atoms. Applied to a set of 141 well-resolved nonhomologous protein structures, the classification yields 11 families of recurrent arrangements. In addition, fragments that are structurally intermediate between the families are found; they reveal the continuity of the classification. The analysis of the families shows that the α helix and β hairpin axes can adopt virtually all relative orientations, with, however, some preferable orientations; moreover, according to the orientation, preferences in the left/right handedness of the α–β connection are observed. These preferences can be explained by favorable side by side packing of the α helix and the β hairpin, local interactions in the region of the α–β connection or stabilizing environments in the parent protein. Furthermore, fold recognition procedures and structure prediction algorithms coupled to database-derived potentials suggest that the preferable nature of these arrangements does not imply their intrinsic stability. They usually accommodate a large number of sequences, of which only a subset is predicted to stabilize the motif. The motifs predicted as stable could correspond to nuclei formed at the very beginning of the folding process. Proteins 30:193–212, 1998. © 1998 Wiley-Liss, Inc.     

5α‐Androst‐16‐en‐3α‐ol β‐D‐Glucuronide,Precursor of 5α‐Androst‐16‐en‐3α‐ol in Human Sweat

5α‐Androst‐16‐en‐3α‐ol (α‐androstenol) is an important contributor to human axilla sweat odor. It is assumed that α‐andostenol is excreted from the apocrine glands via a H₂O‐soluble conjugate, and this precursor was formally characterized in this study for the first time in human sweat. The possible H₂O‐soluble precursors, sulfate and glucuronide derivatives, were synthesized as analytical standards, i.e., α‐androstenol, β‐androstenol sulfates, 5α‐androsta‐5,16‐dien‐3β‐ol (β‐androstadienol) sulfate, α‐androstenol β‐glucuronide, α‐androstenol α‐glucuronide, β‐androstadienol β‐glucuronide, and α‐androstenol β‐glucuronide furanose. The occurrence of α‐androstenol β‐glucuronide was established by ultra performance liquid chromatography (UPLC)/MS (heated electrospray ionization (HESI)) in negative‐ion mode in pooled human sweat, containing eccrine and apocrine secretions and collected from 25 female and 24 male underarms. Its concentration was of 79 ng/ml in female secretions and 241 ng/ml in male secretions. The release of α‐androstenol was observed after incubation of the sterile human sweat or α‐androstenol β‐glucuronide with a commercial glucuronidase enzyme, the urine‐isolated bacteria Streptococcus agalactiae, and the skin bacteria Staphylococcus warneri DSM 20316, Staphylococcus haemolyticus DSM 20263, and Propionibacterium acnes ATCC 6919, reported to have β‐glucuronidase activities. We demonstrated that if α‐ and β‐androstenols and androstadienol sulfates were present in human sweat, their concentrations would be too low to be considered as potential precursors of malodors; therefore, the H₂O‐soluble precursor of α‐androstenol in apocrine secretion should be a β‐glucuronide.     

Kappa opioids promote the proliferation of astrocytes via Gβγ and β‐arrestin 2‐dependent MAPK‐mediated pathways

GTP binding regulatory protein (G protein)‐coupled receptors can activate MAPK pathways via G protein‐dependent and ‐independent mechanisms. However, the physiological outcomes correlated with the cellular signaling events are not as well characterized. In this study, we examine the involvement of G protein and β‐arrestin 2 pathways in kappa opioid receptor‐induced, extracellular signal‐regulated kinase 1/2 (ERK1/2)‐mediated proliferation of both immortalized and primary astrocyte cultures. As different agonists induce different cellular signaling pathways, we tested the prototypic kappa agonist, U69593 as well as the structurally distinct, non‐nitrogenous agonist, C(2)‐methoxymethyl salvinorin B (MOM‐Sal‐B). In immortalized astrocytes, U69593, activated ERK1/2 by a rapid (min) initial stimulation that was sustained over 2 h and increased proliferation. Sequestration of activated Gβγ subunits attenuated U69593 stimulation of ERK1/2 and suppressed proliferation in these cells. Furthermore, small interfering RNA silencing of β‐arrestin 2 diminished sustained ERK activation induced by U69593. In contrast, MOM‐Sal‐B induced only the early phase of ERK1/2 phosphorylation and did not affect proliferation of immortalized astrocytes. In primary astrocytes, U69593 produced the same effects as seen in immortalized astrocytes. MOM‐Sal‐B elicited sustained ERK1/2 activation which was correlated with increased primary astrocyte proliferation. Proliferative actions of both agonists were abolished by either inhibition of ERK1/2, Gβγ subunits or β‐arrestin 2, suggesting that both G protein‐dependent and ‐independent ERK pathways are required for this outcome.     

Interaction of antidiabetic α‐glucosidase inhibitors and gut bacteria α‐glucosidase

Carbohydrate hydrolyzing α‐glucosidases are commonly found in microorganisms present in the human intestine microbiome. We have previously reported crystal structures of an α‐glucosidase from the human gut bacterium Blaubia (Ruminococcus) obeum (Ro‐αG1) and its substrate preference/specificity switch. This novel member of the GH31 family is a structural homolog of human intestinal maltase‐glucoamylase (MGAM) and sucrase–isomaltase (SI) with a highly conserved active site that is predicted to be common in Ro‐αG1 homologs among other species that colonize the human gut. In this report, we present structures of Ro‐αG1 in complex with the antidiabetic α‐glucosidase inhibitors voglibose, miglitol, and acarbose and supporting binding data. The in vitro binding of these antidiabetic drugs to Ro‐αG1 suggests the potential for unintended in vivo crossreaction of the α‐glucosidase inhibitors to bacterial α‐glucosidases that are present in gut microorganism communities. Moreover, analysis of these drug‐bound enzyme structures could benefit further antidiabetic drug development.     

Syntheses and anti‐tubercular activity of β‐substituted and α,β‐disubstituted peptidyl β‐aminoboronates and boronic acids

Tuberculosis is still affecting millions of people worldwide, and new resistant strains of Mycobacterium tuberculosis are being found. It is therefore necessary to find new compounds for treatment. In this paper, we report the synthesis and in vitro testing of peptidyl β‐aminoboronic acids and β‐aminoboronates with anti‐tubercular activity. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.     

IFN‐γ inhibits basal and α‐MSH‐induced melanogenesis

Inflammatory cytokines are closely related to pigmentary changes. In this study, the effects of IFN‐γ on melanogenesis were investigated. IFN‐γ inhibits basal and α‐MSH‐induced melanogenesis in B16 melanoma cells and normal human melanocytes. MITF mRNA and protein expressions were significantly inhibited in response to IFN‐γ. IFN‐γ inhibited CREB binding to the MITF promoter but did not affect CREB phosphorylation. Instead, IFN‐γ inhibited the association of CBP and CREB through the increased association between CREB binding protein (CBP) and STAT1. These findings suggest that IFN‐γ inhibits both basal and α‐MSH‐induced melanogenesis by inhibiting MITF expression. The inhibitory action of IFN‐γ in α‐MSH‐induced melanogenesis is likely to be associated with the sequestration of CBP via the association between CBP and STAT1. These data suggest that IFN‐γ plays a role in controlling inflammation‐ or UV‐induced pigmentary changes.     

Mir‐29b promotes human aortic valve interstitial cell calcification via inhibiting TGF‐β3 through activation of wnt3/β‐catenin/Smad3 signaling

Herein, we hypothesized that pro‐osteogenic MicroRNAs (miRs) could play functional roles in the calcification of the aortic valve and aimed to explore the functional role of miR‐29b in the osteoblastic differentiation of human aortic valve interstitial cells (hAVICs) and the underlying molecular mechanism. Osteoblastic differentiation of hAVICs isolated from human calcific aortic valve leaflets obtained intraoperatively was induced with an osteogenic medium. Alizarin red S staining was used to evaluate calcium deposition. The protein levels of osteogenic markers and other proteins were evaluated using western blotting and/or immunofluorescence while qRT‐PCR was applied for miR and mRNA determination. Bioinformatics and luciferase reporter assay were used to identify the possible interaction between miR‐29b and TGF‐β3. Calcium deposition and the number of calcification nodules were pointedly and progressively increased in hAVICs during osteogenic differentiation. The levels of osteogenic and calcification markers were equally increased, thus confirming the mineralization of hAVICs. The expression of miR‐29b was significantly increased during osteoblastic differentiation. Furthermore, the osteoblastic differentiation of hAVICs was significantly inhibited by the miR‐29b inhibition. TGF‐β3 was markedly downregulated while Smad3, Runx2, wnt3, and β‐catenin were significantly upregulated during osteogenic induction at both the mRNA and protein levels. These effects were systematically induced by miR‐29b overexpression while the inhibition of miR‐29b showed the inverse trends. Moreover, TGF‐β3 was a direct target of miR‐29b. Inhibition of miR‐29b hinders valvular calcification through the upregulation of the TGF‐β3 via inhibition of wnt/β‐catenin and RUNX2/Smad3 signaling pathways.     

miR‐145 is differentially regulated by TGF‐β1 and ischaemia and targets Disabled‐2 expression and wnt/β‐catenin activity

The effect of wnt/β‐catenin signalling in the response to acute myocardial infarction (AMI) remains controversial. The membrane receptor adaptor protein Disabled‐2 (Dab2) is a tumour suppressor protein and has a critical role in stem cell specification. We recently demonstrated that down‐regulation of Dab2 regulates cardiac protein expression and wnt/β‐catenin activity in mesenchymal stem cells (MSC) in response to transforming growth factor‐β₁ (TGF‐β₁). Although Dab2 expression has been shown to have effects in stem cells and tumour suppression, the molecular mechanisms regulating this expression are still undefined. We identified putative binding sites for miR‐145 in the 3′‐UTR of Dab2. In MSC in culture, we observed that TGF‐β₁ treatment led to rapid and sustained up‐regulation of pri–miR‐145. Through gain and loss of function studies we demonstrate that miR‐145 up‐regulation was required for the down‐regulation of Dab2 and increased β‐catenin activity in response to TGF‐β₁. To begin to define how Dab2 might regulate wnt/β‐catenin in the heart following AMI, we quantified myocardial Dab2 as a function of time after left anterior descending ligation. There was no significant Dab2 expression in sham‐operated myocardium. Following AMI, Dab2 levels were rapidly up‐regulated in cardiac myocytes in the infarct border zone. The increase in cardiac myocyte Dab2 expression correlated with the rapid and sustained down‐regulation of myocardial pri–miR‐145 expression following AMI. Our data demonstrate a novel and critical role for miR‐145 expression as a regulator of Dab2 expression and β‐catenin activity in response to TGF‐β₁ and hypoxia.     

Eu3+‐tetrakis β‐diketonate complexes for solid‐state lighting application

Eu³⁺–β‐diketonate complexes are used, for example, in solid‐state lighting (SSL) or light‐converting molecular devices. However, their low emission quantum efficiency due to water molecules coordinated to Eu³⁺ and low photostability are still problems to be addressed. To overcome such challenges, we synthesized Eu³⁺ tetrakis complexes based on [Q][Eu(tfaa)₄] and [Q][Eu(dbm)₄] (Q1 = C₂₆H₅₆N⁺, Q2 = C₁₉H₄₂N⁺, and Q3 = C₁₇H₃₈N⁺), replacing the water molecules in the tris stoichiometry. The tetrakis β‐diketonates showed desirable thermal stability for SSL and, under excitation at 390 nm, they displayed the characteristic Eu³⁺ emission in the red spectral region. The quantum efficiencies of the dbm complexes achieved values as high as 51%, while the tfaa complexes exhibited lower quantum efficiencies (28–33%), but which were superior to those reported for the tris complexes. The structures were evaluated using the Sparkle/PM7 model and comparing the theoretical and the experimental Judd–Ofelt parameters. [Q1][Eu(dbm)₄] was used to coat a near‐UV light‐emitting diode (LED), producing a red‐emitting LED prototype that featured the characteristic emission spectrum of [Q1][Eu(dbm)₄]. The emission intensity of this prototype decreased only 7% after 30 h, confirming its high photostability, which is a notable result considering Eu³⁺ complexes, making it a potential candidate for SSL.     

Biosynthesis of the leucine derived α‐, β‐ and γ‐hydroxynitrile glucosides in barley (Hordeum vulgare L.)

Barley (Hordeum vulgare L.) produces five leucine‐derived hydroxynitrile glucosides (HNGs), of which only epiheterodendrin is a cyanogenic glucoside. The four non‐cyanogenic HNGs are the β‐HNG epidermin and the γ‐HNGs osmaronin, dihydroosmaronin and sutherlandin. By analyzing 247 spring barley lines including landraces and old and modern cultivars, we demonstrated that the HNG level varies notably between lines whereas the overall ratio between the compounds is constant. Based on sequence similarity to the sorghum (Sorghum bicolor) genes involved in dhurrin biosynthesis, we identified a gene cluster on barley chromosome 1 putatively harboring genes that encode enzymes in HNG biosynthesis. Candidate genes were functionally characterized by transient expression in Nicotiana benthamiana. Five multifunctional P450s, including two CYP79 family enzymes and three CYP71 family enzymes, and a single UDP‐glucosyltransferase were found to catalyze the reactions required for biosynthesis of all five barley HNGs. Two of the CYP71 enzymes needed to be co‐expressed for the last hydroxylation step in sutherlandin synthesis to proceed. This observation, together with the constant ratio between the different HNGs, suggested that HNG synthesis in barley is organized within a single multi‐enzyme complex.     

Human α‐amino‐β‐carboxymuconate‐ε‐semialdehyde decarboxylase (ACMSD): A structural and mechanistic unveiling

Human α‐amino‐β‐carboxymuconate‐ε‐semialdehyde decarboxylase determines the fate of tryptophan metabolites in the kynurenine pathway by controlling the quinolinate levels for de novo nicotinamide adenine dinucleotide biosynthesis. The unstable nature of its substrate has made gaining insight into its reaction mechanism difficult. Our electron paramagnetic resonance (EPR) spectroscopic study on the Cu‐substituted human enzyme suggests that the native substrate does not directly ligate to the metal ion. Substrate binding did not result in a change of either the hyperfine structure or the super‐hyperfine structure of the EPR spectrum. We also determined the crystal structure of the human enzyme in its native catalytically active state (at 1.99 Å resolution), a substrate analogue‐bound form (2.50 Å resolution), and a selected active site mutant form with one of the putative substrate binding residues altered (2.32 Å resolution). These structures illustrate that each asymmetric unit contains three pairs of dimers. Consistent with the EPR findings, the ligand‐bound complex structure shows that the substrate analogue does not directly coordinate to the metal ion but is bound to the active site by two arginine residues through noncovalent interactions. Proteins 2015; 83:178–187. © 2014 Wiley Periodicals, Inc.     

Functional α1‐ and β2‐adrenergic receptors in human osteoblasts

Central (hypothalamic) control of bone mass is proposed to be mediated through β2‐adrenergic receptors (β2‐ARs). While investigations in mouse bone cells suggest that epinephrine enhances both RANKL and OPG mRNA via both β‐ARs and α‐ARs, whether α‐ARs are expressed in human bone cells is controversial. The current study investigated the expression of α1‐AR and β2‐AR mRNA and protein and the functional role of adrenergic stimulation in human osteoblasts (HOBs). Expression of α1B‐ and β2‐ARs was examined by RT‐PCR, immunofluorescence microscopy and Western blot (for α1B‐ARs). Proliferation in HOBs was assessed by ³H‐thymidine incorporation and expression of RANKL and OPG was determined by quantitative RT‐PCR. RNA message for α1B‐ and β2‐ARs was expressed in HOBs and MG63 human osteosarcoma cells. α1B‐ and β2‐AR immunofluorescent localization in HOBs was shown for the first time by deconvolution microscopy. α1B‐AR protein was identified in HOBs by Western blot. Both α1‐agonists and propranolol (β‐blocker) increased HOB replication but fenoterol, a β2‐agonist, inhibited it. Fenoterol nearly doubled RANKL mRNA and this was inhibited by propranolol. The α1‐agonist cirazoline increased OPG mRNA and this increase was abolished by siRNA knockdown of α1B‐ARs in HOBs. These data indicate that both α1‐ARs and β2‐ARs are present and functional in HOBs. In addition to β2‐ARs, α1‐ARs in human bone cells may play a role in modulation of bone turnover by the sympathetic nervous system. J. Cell. Physiol. 220: 267–275, 2009. © 2009 Wiley‐Liss, Inc.     

Solution properties of γ‐crystallins: Hydration of fish and mammal γ‐crystallins

Lens γ crystallins are found at the highest protein concentration of any tissue, ranging from 300 mg/mL in some mammals to over 1000 mg/mL in fish. Such high concentrations are necessary for the refraction of light, but impose extreme requirements for protein stability and solubility. γ‐crystallins, small stable monomeric proteins, are particularly associated with the lowest hydration regions of the lens. Here, we examine the solvation of selected γ‐crystallins from mammals (human γD and mouse γS) and fish (zebrafish γM2b and γM7). The thermodynamic water binding coefficient B₁ could be probed by sucrose expulsion, and the hydrodynamic hydration shell of tightly bound water was probed by translational diffusion and structure‐based hydrodynamic boundary element modeling. While the amount of tightly bound water of human γD was consistent with that of average proteins, the water binding of mouse γS was found to be relatively low. γM2b and γM7 crystallins were found to exhibit extremely low degrees hydration, consistent with their role in the fish lens. γM crystallins have a very high methionine content, in some species up to 15%. Structure‐based modeling of hydration in γM7 crystallin suggests low hydration is associated with the large number of surface methionine residues, likely in adaptation to the extremely high concentration and low hydration environment in fish lenses. Overall, the degree of hydration appears to balance stability and tissue density requirements required to produce and maintain the optical properties of the lens in different vertebrate species.     

Activation of Wnt/β‐catenin signalling is required for TGF‐β/Smad2/3 signalling during myofibroblast proliferation

Fibrosis in animal models and human diseases is associated with aberrant activation of the Wnt/β‐catenin pathway. Despite extensive research efforts, effective therapies are still not available. Myofibroblasts are major effectors, responsible for extracellular matrix deposition. Inhibiting the proliferation of the myofibroblast is crucial for treatment of fibrosis. Proliferation of myofibroblasts can have many triggering effects that result in fibrosis. In recent years, the Wnt pathway has been studied as an underlying factor as a primary contributor to fibrotic diseases. These efforts notwithstanding, the specific mechanisms by which Wnt‐mediated promotes fibrosis reaction remain obscure. The central role of the transforming growth factor‐β (TGF‐β) and myofibroblast activity in the pathogenesis of fibrosis has become generally accepted. The details of interaction between these two processes are not obvious. The present investigation was conducted to evaluate the level of sustained expression of fibrosis iconic proteins (vimentin, α‐SMA and collagen I) and the TGF‐β signalling pathway that include smad2/3 and its phosphorylated form p‐smad2/3. Detailed analysis of the possible molecular mechanisms mediated by β‐catenin revealed epithelial–mesenchymal transition and additionally demonstrated transitions of fibroblasts to myofibroblast cell forms, along with increased activity of β‐catenin in regulation of the signalling network, which acts to counteract autocrine TGF‐β/smad2/3 signalling. A major outcome of this study is improved insight into the mechanisms by which epithelial and mesenchymal cells activated by TGFβ1‐smad2/3 signalling through Wnt/β‐catenin contribute to lung fibrosis.     

Characterization of an Importin α/β‐recognized nuclear localization signal in β‐dystroglycan

β‐dystroglycan (β‐DG) is a widely expressed transmembrane protein that plays important roles in connecting the extracellular matrix to the cytoskeleton, and thereby contributing to plasma membrane integrity and signal transduction. We previously observed nuclear localization of β‐DG in cultured cell lines, implying the existence of a nuclear targeting mechanism that directs it to the nucleus instead of the plasma membrane. In this study, we delineate the nuclear import pathway of β‐DG, characterizing a functional nuclear localization signal (NLS) in the β‐DG cytoplasmic domain, within amino acids 776–782. The NLS either alone or in the context of the whole β‐DG protein was able to target the heterologous GFP protein to the nucleus, with site‐directed mutagenesis indicating that amino acids R⁷⁷⁹ and K⁷⁸⁰ are critical for NLS functionality. The nuclear transport molecules Importin (Imp)α and Impβ bound with high affinity to the NLS of β‐DG and were found to be essential for NLS‐dependent nuclear import in an in vitro reconstituted nuclear transport assay; cotransfection experiments confirmed the dependence on Ran for nuclear accumulation. Intriguingly, experiments suggested that tyrosine phosphorylation of β‐DG may result in cytoplasmic retention, with Y⁸⁹² playing a key role. β‐DG thus follows a conventional Impα/β‐dependent nuclear import pathway, with important implications for its potential function in the nucleus. J. Cell. Biochem. 110: 706–717, 2010. © 2010 Wiley‐Liss, Inc.     

Novel renin inhibitors containing derivatives of N‐alkylleucyl‐β‐hydroxy‐γ‐amino acids

In search for new drugs lowering arterial blood pressure, which could be applied in anti‐hypertensive therapy, research concerning agents blocking of renin‐angiotensin‐aldosteron system has been conducted. Despite many years of research conducted at many research centers around the world, aliskiren is the only one renin inhibitor, which is used up to now. Four novel potential renin inhibitors, having structure based on the peptide fragment 8–13 of human angiotensinogen, a natural substrate for renin, were designed and synthesized. All these inhibitors contain unnatural moieties that are derivatives of N‐methylleucyl‐β‐hydroxy‐γ‐amino acids at the P₂‐P₁' position: 4‐[N‐(N‐methylleucyl)‐amino]‐3‐hydroxy‐7‐(3‐nitroguanidino)‐heptanoic acid (AHGHA), 4‐[N‐(N‐methylleucyl)‐amino]‐3‐hydroxy‐5‐phenyl‐pentanoic acid (AHPPA) or 4‐[N‐(N‐methylleucyl)‐amino]‐8‐benzyloxycarbonylamino‐3‐hydroxyoctanoic acid (AAHOA). The previously listed synthetic β‐hydroxy‐γ‐amino acids constitute pseudodipeptidic units that correspond to the P₁‐P₁' position of the inhibitor molecule. An unnatural amino acid, 4‐methoxyphenylalanin (Phe(4‐OMe)), was introduced at the P₃ position of the obtained compounds. Three of these compounds contain isoamylamide of 6‐aminohexanoic acid (ε‐Ahx‐Iaa) at the P₂'‐P₃' position. The proposed modifications of the selected human angiotensinogen fragment are intended to increase bioactivity, bioavailability, and stability of the inhibitor molecule in body fluids and tissues. The inhibitor Boc‐Phe(4‐OMe)‐MeLeu‐AHGHA‐OEt was obtained in the form of an ethyl ester. The hydrophobicity coefficient, expressed as log P varied between 3.95 and 8.17. In vitro renin inhibitory activity of all obtained compounds was contained within the range 10^?6‐10^?9 M. The compound Boc‐Phe(4‐OMe)‐MeLeu‐AHPPA‐Ahx‐Iaa proved to be the most active (IC₅₀ = 1.05 × 10^?9 M). The compounds Boc‐Phe(4‐OMe)‐MeLeu‐AHGHA‐Ahx‐Iaa and Boc‐Phe(4‐OMe)‐MeLeu‐AHPPA‐Ahx‐Iaa are resistant to chymotrypsin. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.     

A Potential Role for 5‐Androstene‐3β,7β,17β‐triol in Obesity and Metabolic Syndrome

Metabolic syndrome is marked by perturbed glucocorticoid (GC) signaling, systemic inflammation, and altered immune status. Dehydroepiandrosterone (DHEA), a major circulating adrenal steroid and dietary supplement, demonstrates antiobesity, anti‐inflammatory, GC‐opposing and immune‐modulating activity when administered to rodents. However, plasma DHEA levels failed to correlate with metabolic syndrome and oral replacement therapy provided only mild benefits to patients. Androstene‐3β,7β,17β‐triol (β‐AET) an anti‐inflammatory metabolite of DHEA, also exhibits GC‐opposing and immune‐modulating activity when administered to rodents. We hypothesized a role for β‐AET in obesity. We now report that plasma levels of β‐AET positively correlate with BMI in healthy men and women. Together with previous studies, the observations reported here may suggest a compensatory role for β‐AET in preventing the development of metabolic syndrome. The β‐AET structural core may provide the basis for novel pharmaceuticals to treat this disease.     

Lectin BS‐I inhibits cell migration and invasion via AKT/GSK‐3β/β‐catenin pathway in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is most common malignant cancer worldwide; however, the mortality rate of HCC remains high due to the invasion and metastasis of HCC. Thus, exploring novel treatments to prevent the invasion of HCC is needed for improving clinical outcome of this fatal disease. In this study, we identified lectin from Bandeiraea simplicifolia seeds (BS‐I) binds to metastasis‐associated HCC cell surface glycans by a lectin microarray and inhibits HCC cell migration and invasion through downregulating the matrix metalloproteinase 2 (MMP2), matrix metalloproteinase 9 (MMP9) and urokinase‐type plasminogen activator (uPA) production. These effects of BS‐I were mediated by inhibiting the activation of AKT/GSK‐3β/β‐catenin pathway and depended on specificity of lectin BS‐I binding to GalNAc. GSK3β inhibitors rescued BS‐I‐mediated inhibition of migration and invasion of HCC cell. Further, we identified that lectin BS‐I interacts with sGrp78, affects membrane localization of sGrp78 and attenuates the binding of sGrp78 and p85 to inhibit the activation of AKT/GSK‐3β/β‐catenin pathway. Overexpression of Grp78 or P85 rescues BS‐I‐mediated inhibition of migration and invasion of HCC cell. These findings demonstrated for the first time that BS‐I can act as a novel potential drug to prevent the invasion of HCC.