Progress of the talin and the mechanical basis theory of memory / 解剖学报

Memory loss induced by aging and hypoxia is very common, so exploring the mechanism of memory production, storage and retrieval is of great significance to daily life and clinical work. The storage and retrieval of memory is probably similar to the computer. We summarized the research progress of MeshCODE theory, the mechanical basis of memory. Memory loss in certain diseases (such as Alzheimer's disease) or pathological conditions (such as aging, lack of oxygen) may be associated with abnormal folding of talin, a mechanosensitive protein. It can dynamically regulate synaptic activity by changing the state of the domain, storing or updating information about small changes in mechanical forces in binary form, and initiating chemical processes such as ligand redistribution in neurons, so that memory is stored in the brain in a binary format, known as the MeshCODE theory.

Molecular dynamics simulation of force-regulated interaction between talin and Rap1b / 生物医学工程学杂志

The binding of talin-F0 domain to ras-related protein 1b (Rap1b) plays an important role in the formation of thrombosis. However, since talin is a force-sensitive protein, it remains unclear whether and how force regulates the talin-F0/Rap1b interaction. To explore the effect of force on the binding affinity and the dynamics mechanisms of talin-F0/Rap1b, molecular dynamics simulation was used to observe and compare the changes in functional and conformational information of the complex under different forces. Our results showed that when the complex was subjected to tensile forces, there were at least two dissociation pathways with significantly different mechanical strengths. The key event determining the mechanical strength difference between the two pathways was whether the β4 sheet of the F0 domain was pulled away from the original β1-β4 parallel structure. As the force increased, the talin-F0/Rap1b interaction first strengthened and then weakened, exhibiting the signature of a transition from catch bonds to slip bonds. The mechanical load of 20 pN increased the interaction index of two residue pairs, ASP 54-ARG 41 and GLN 18-THR 65, which resulted in a significant increase in the affinity of the complex. This study predicts the regulatory mechanism of the talin-F0/Rap1b interaction by forces in the intracellular environment and provides novel ideas for the treatment of related diseases and drug development.

Talin1 is highly expressed in the fallopian tube and chorionic villi to promote trophoblast invasion in tubal pregnancy / 南方医科大学学报

OBJECTIVE@#To investigate the expression of Talin1 in the fallopian tube and chorionic villi in patients with tubal pregnancy and its role in regulating invasion and migration of trophoblasts.@*METHODS@#Immunohistochemistry and Western blotting were used to detect the localization and expression level of Talin1 in the fallopian tube and chorionic villi in patients with tubal pregnancy and in women with normal pregnancy. In the cell experiment, HTR-8/SVneo cells was transfected with Talin1 siRNA and the changes in cell invasion and migration were assessed using scratch assay and Transwell assay. The expressions of MMP-2, MMP-9, N-cadherin and Snail in the transfected cells were detected by qRT-PCR and Western blotting.@*RESULTS@#Positive expression of Talin1 was detected in both normal fallopian tube tissues and tissues from women tubal pregnancy, and its expression was localized mainly in the cytoplasm of cilia cells. The expression level of Talin1 was significantly higher in both the fallopian tube and chorionic villi in women with tubal pregnancy than in normal fallopian tube and chorionic villi samples (P < 0.01). In HTR-8/SVneo cells, transfection with Talin1 siRNA significantly inhibited cell invasion (P < 0.01) and migration (P < 0.05), down-regulated the expression of N-cadherin, MMP-2 and Snail (P < 0.05), and up-regulated the expression of MMP-9 in the cells (P < 0.05).@*CONCLUSION@#The expression of Talin1 in the fallopian tube and chorionic villi is significantly increased in women with tubal pregnancy, suggesting the association of Talin1-regulated trophoblast cell invasion with the occurrence of tubal pregnancy.

LPS stimulating neutrophils firmly adhered to ICAM-1 to form extracellular traps depends on integrin Mac-1 and cytoskeletal proteins / 生物医学工程学杂志

Neutrophil extracellular traps (NETs) play an important role in the formation of immunothrombosis. However, how vascular endothelial cells mediate the formation of NETs has not been fully understood. We stimulated neutrophils firmly attached on the endothelial cell surface intercellular adhesion molecule-1 (ICAM-1) with lipopolysaccharide (LPS) or phorbol-12-myristate-13-acetate (PMA) for 4 h, then labeled NETs-DNA with Sytox green dye and the formation of NETs was observed by fluorescent microscopy. The area and fluorescence intensity of NETs-DNA were analyzed to quantify the formation of NETs. The results showed that both PMA and LPS were able to induce firmly adhered neutrophils on ICAM-1 to produce NETs. NETs induced by PMA were independent of neither β2 integrin lymphocyte function-associated antigen-1 (LFA-1) nor macrophage antigen complex-1 (Mac-1). In contrast, LPS-stimulated NETs were mediated by Mac-1 integrin, but not by LFA-1. After inhibition of actin filaments or Talin-1, the formation of NETs irrespective of the stimulus was significantly reduced. This study reveals the mechanism of the direct interaction between neutrophils and endothelial cells to produce NETs under inflammatory conditions, providing a new theoretical basis for the treatment of related diseases and the development of new drugs.

Changes in expression of Talin1 and F-actin during serum-induced proliferation of pulmonary artery smooth muscle cells of rats with hepatopulmonary syndrome / 中华麻醉学杂志

Objective To evaluate the changes in the expression of Talin1 and F-actin during ser-um-induced proliferation of pulmonary artery smooth muscle cells ( PASMCs) of rats with hepatopulmonary syndrome ( HPS) . Methods Twenty healthy male Sprague-Dawley rats, weighing 220-250 g, were used for producing HPS by chronic ligation of the common bile duct. Blood samples from the abdominal aorta were collected to prepare serum. Primarily cultured PASMCs obtained from rats were seed in 6- or 96-well plates and divided into 2 groups using a random number table method: control group ( group C) and HPS group ( group HPS) , with 24 wells in each group ( for 6-well plates) or with 30 wells in each group ( for 96-well plates) . In C and HPS groups, normal rat serum or HPS rat serum were added, respectively, with the final concentration of 5％. At 24, 48 and 72 h of incubation, the expression of Talin1, F-actin and G-actin was determined by Western blot, the F-actin∕G-actin ratio was calculated, and the proliferation of PASMCs was measured by 3H-TdR incorporation and CCK-8 assays. Results Compared with group C, the proliferation of PASMCs was significantly enhanced, the expression of Talin1 was up-regulated, and the F-actin∕G-actin ratio was increased in group HPS ( P<0. 05) . The proliferation of PASMCs was gradually en-hanced, the expression of Talin1 was gradually up-regulated, and the F-actin∕G-actin ratio was gradually increased with the prolonged incubation time in group HPS (P<0. 05). Conclusion The mechanism by which the HPS rat serum induces proliferation of PASMCs may be related to up-regulating the expression of Talin1 and F-actin.

Trypanosoma cruzi down-regulates mechanosensitive proteins in cardiomyocytes

BACKGROUND Cardiac physiology depends on coupling and electrical and mechanical coordination through the intercalated disc. Focal adhesions offer mechanical support and signal transduction events during heart contraction-relaxation processes. Talin links integrins to the actin cytoskeleton and serves as a scaffold for the recruitment of other proteins, such as paxillin in focal adhesion formation and regulation. Chagasic cardiomyopathy is caused by infection by Trypanosoma cruzi and is a debilitating condition comprising extensive fibrosis, inflammation, cardiac hypertrophy and electrical alterations that culminate in heart failure. OBJECTIVES Since mechanotransduction coordinates heart function, we evaluated the underlying mechanism implicated in the mechanical changes, focusing especially in mechanosensitive proteins and related signalling pathways during infection of cardiac cells by T. cruzi. METHODS We investigated the effect of T. cruzi infection on the expression and distribution of talin/paxillin and associated proteins in mouse cardiomyocytes in vitro by western blotting, immunofluorescence and quantitative real-time polymerase chain reaction (qRT-PCR). FINDINGS Talin and paxillin spatial distribution in T. cruzi-infected cardiomyocytes in vitro were altered associated with a downregulation of these proteins and mRNAs levels at 72 h post-infection (hpi). Additionally, we observed an increase in the activation of the focal adhesion kinase (FAK) concomitant with increase in β-1-integrin at 24 hpi. Finally, we detected a decrease in the activation of FAK at 72 hpi in T. cruzi-infected cultures. MAIN CONCLUSION The results suggest that these changes may contribute to the mechanotransduction disturbance evidenced in chagasic cardiomyopathy.

Relationship between Talin and its signaling pathway and hepatocellular carcinoma / 国际外科学杂志

Alterations of cell adhesion of tumor cells is the initial step of invasion and metastasis of tumor cells.Integrin receptors are cell surface receptors with critical functions in cell adhesion and migration,which can mediate many signaling pathway occurred,including the integrin/FAK signaling pathway,directly or indirectly affecting tumor recurrence and metastasis.Integrin/FAK signaling pathway is thought to play an impartant role in integrin-mediated signaling transduction pathway leading to adhesion and metastasis of hepatocellular carcinoma.Talin is the first cytoskeletal protein that has been proposed to act as the final common step in integrin activation,which is a major component of the focal adhesion.This study reviews the construction and function of talin,its reaction with integrin/FAK signaling pathway,as well as its relationship with hepatocellular carcinoma and other tumors.