Objective To investigate the protective effect and mechanism of J147 on the injury of human neuroblastoma cells(SH-SY5Y)induced by high glucose(HG).Methods We established HG-induced SH-SY5Y cell injury model.Then SH-SY5Y cells were divided into blank control(Con)group HG group,HG+J147 0.5 μmol/L(HG+J147 0.5)group,HG+J147 1 μmol/L(HG+J147 1)group,HG+J147 2 μmol/L(HG+J147 2)group,HG+PI3K/AKT inhibitor LY294002(LY)10 μmol/L(HG+LY)group,HG+ERK1/2 inhibitor U0126(U0)5 μmol/L(HG+U0)group,HG+J147 2 μmol/L+LY 10 μmol/L(HG+J147 2+LY)group,HG+J147 2 μmol/L+U0 5 μmol/L(HG+J147 2+U0)group.Cell viability was detected by MTS cell proliferation and toxicity detection kit;LDH activity was tested by lactate dehydrogenase kit;morphological changes of SH-SY5Y cells were evaluated by microscope;cell apoptosis was detected by flow cytometry;and apoptosis-related proteins(Bcl-2,Bax)and signaling pathway-related proteins(p-AKT,AKT,p-ERK1/2,ERK1/2,p-CREB,CREB,BDNF)were detected by Western blot.Results Compared with Con group,the cell viability,Bcl-2/Bax ratio,p-AKT/AKT,p-ERK/ERK,p-CREB/CREB and BDNF protein expressions decreased(P<0.01),while LDH activity and apoptosis rate increased in HG group(P<0.01).Compared with HG group,the cell viability,Bcl-2/Bax ratio,p-AKT/AKT,p-ERK/ERK,p-CREB/CREB and BDNF protein expressions increased(P<0.01),while LDH activity and apoptosis rate decreased in HG+J147 2 group(P<0.01).Compared with HG+J147 2 group,the cell viability,Bcl-2/Bax ratio,p-AKT/AKT and BDNF protein expression decreased(P<0.05 or P<0.01),while LDH activity and apoptosis rate increased(P<0.05 or P<0.01),the expression of p-ERK/ERK protein in HG+J147 2+LY group decreased(P<0.05),and the expression of p-CREB/CREB protein in HG+J147 2+U0 group decreased in HG+J147 2+LY and HG+J147 2+U0 groups(P<0.05).Conclusions J147 can alleviate HG-induced SH-SY5Y cell damage,and the mechanism may be related to the activation of PI3K/AKT and ERK1/2 signaling and the reduction of apoptosis.

Staphylococcus aureus is the most important Gram-positive colonizer of human skin and nasal passage, causing high morbidity and mortality. SD-repeat containing protein D (SdrD), an MSCRAMM (Microbial Surface Components Recognizing Adhesive Matrix Molecules) family surface protein, plays an important role in S. aureus adhesion and pathogenesis, while its binding target and molecular mechanism remain largely unknown. Here we solved the crystal structures of SdrD N2-N3 domain and N2-N3-B1 domain. Through structural analysis and comparisons, we characterized the ligand binding site of SdrD, and proposed a featured sequence motif of its potential ligands. In addition, the structures revealed for the first time the interactions between B1 domain and N2-N3 domain among B domain-containing MSCRAMMs. Our results may help in understanding the roles SdrD plays in S. aureus adhesion and shed light on the development of novel antibiotics.
Amino Acid Sequence ; Bacterial Proteins ; chemistry ; genetics ; metabolism ; Binding Sites ; Calcium ; chemistry ; metabolism ; Calcium-Binding Proteins ; chemistry ; genetics ; metabolism ; Hydrogen Bonding ; Ligands ; Molecular Sequence Data ; Protein Binding ; Protein Structure, Tertiary ; Receptors, Cell Surface ; chemistry ; metabolism ; Recombinant Proteins ; biosynthesis ; chemistry ; genetics ; Sequence Alignment ; Staphylococcus aureus ; metabolism

Bone sialoprotein-binding protein (Bbp), a MSCRAMMs (Microbial Surface Components Recognizing Adhesive Matrix Molecules) family protein expressed on the surface of Staphylococcus aureus (S. aureus), mediates adherence to fibrinogen α (Fg α), a component in the extracellular matrix of the host cell and is important for infection and pathogenesis. In this study, we solved the crystal structures of apo-Bbp(273-598) and Bbp(273-598)-Fg α(561-575) complex at a resolution of 2.03 Å and 1.45 Å, respectively. Apo-Bbp(273-598) contained the ligand binding region N2 and N3 domains, both of which followed a DE variant IgG fold characterized by an additional D1 strand in N2 domain and D1' and D2' strands in N3 domain. The peptide mapped to the Fg α(561-575) bond to Bbp(273-598) on the open groove between the N2 and N3 domains. Strikingly, the disordered C-terminus in the apo-form reorganized into a highly-ordered loop and a β-strand G'' covering the ligand upon ligand binding. Bbp(Ala298-Gly301) in the N2 domain of the Bbp(273-598)-Fg α(561-575) complex, which is a loop in the apo-form, formed a short α-helix to interact tightly with the peptide. In addition, Bbp(Ser547-Gln561) in the N3 domain moved toward the binding groove to make contact directly with the peptide, while Bbp(Asp338-Gly355) and Bbp(Thr365-Tyr387) in N2 domain shifted their configurations to stabilize the reorganized C-terminus mainly through strong hydrogen bonds. Altogether, our results revealed the molecular basis for Bbp-ligand interaction and advanced our understanding of S. aureus infection process.
Bacterial Proteins ; chemistry ; genetics ; metabolism ; Carrier Proteins ; chemistry ; genetics ; metabolism ; Crystallography, X-Ray ; Fibrinogen ; metabolism ; Ligands ; Models, Molecular ; Mutation ; Peptide Fragments ; chemistry ; metabolism ; Protein Binding ; Protein Structure, Tertiary ; Staphylococcus aureus

Mechanosensitive (MS) channels are extensively studied membrane protein for maintaining intracellular homeostasis through translocating solutes and ions across the membrane, but its mechanisms of channel gating and ion selectivity are largely unknown. Here, we identified the YnaI channel as the Na/K cation-selective MS channel and solved its structure at 3.8 Å by cryo-EM single-particle method. YnaI exhibits low conductance among the family of MS channels in E. coli, and shares a similar overall heptamer structure fold with previously studied MscS channels. By combining structural based mutagenesis, quantum mechanical and electrophysiological characterizations, we revealed that ion selective filter formed by seven hydrophobic methionine (YnaI) in the transmembrane pore determined ion selectivity, and both ion selectivity and gating of YnaI channel were affected by accompanying anions in solution. Further quantum simulation and functional validation support that the distinct binding energies with various anions to YnaI facilitate Na/K pass through, which was defined as binding-block mechanism. Our structural and functional studies provided a new perspective for understanding the mechanism of how MS channels select ions driven by mechanical force.
Cryoelectron Microscopy ; Escherichia coli Proteins ; chemistry ; isolation & purification ; metabolism ; ultrastructure ; Ion Channels ; chemistry ; isolation & purification ; metabolism ; ultrastructure ; Mechanotransduction, Cellular ; Models, Molecular ; Quantum Theory

In the original publication the PDB numbers were not cited.