Sichuan University

About: Sichuan University is a education organization based out in Chengdu, China. It is known for research contribution in the topics: Catalysis & Population. The organization has 107623 authors who have published 102844 publications receiving 1612131 citations. The organization is also known as: Sìchuān Dàxué.

RAP2 mediates mechanoresponses of the Hippo pathway

Abstract: Mammalian cells are surrounded by neighbouring cells and extracellular matrix (ECM), which provide cells with structural support and mechanical cues that influence diverse biological processes1. The Hippo pathway effectors YAP (also known as YAP1) and TAZ (also known as WWTR1) are regulated by mechanical cues and mediate cellular responses to ECM stiffness2,3. Here we identified the Ras-related GTPase RAP2 as a key intracellular signal transducer that relays ECM rigidity signals to control mechanosensitive cellular activities through YAP and TAZ. RAP2 is activated by low ECM stiffness, and deletion of RAP2 blocks the regulation of YAP and TAZ by stiffness signals and promotes aberrant cell growth. Mechanistically, matrix stiffness acts through phospholipase Cγ1 (PLCγ1) to influence levels of phosphatidylinositol 4,5-bisphosphate and phosphatidic acid, which activates RAP2 through PDZGEF1 and PDZGEF2 (also known as RAPGEF2 and RAPGEF6). At low stiffness, active RAP2 binds to and stimulates MAP4K4, MAP4K6, MAP4K7 and ARHGAP29, resulting in activation of LATS1 and LATS2 and inhibition of YAP and TAZ. RAP2, YAP and TAZ have pivotal roles in mechanoregulated transcription, as deletion of YAP and TAZ abolishes the ECM stiffness-responsive transcriptome. Our findings show that RAP2 is a molecular switch in mechanotransduction, thereby defining a mechanosignalling pathway from ECM stiffness to the nucleus.

A consistency and consensus based decision support model for group decision making with multiplicative preference relations

Abstract: In group decision making (GDM) with multiplicative preference relations (also known as pairwise comparison matrices in the Analytical Hierarchy Process), to come to a meaningful and reliable solution, it is preferable to consider individual consistency and group consensus in the decision process. This paper provides a decision support model to aid the group consensus process while keeping an acceptable individual consistency for each decision maker. The concept of an individual consistency index and a group consensus index is introduced based on the Hadamard product of two matrices. Two algorithms are presented in the designed support model. The first algorithm is utilized to convert an unacceptable preference relation to an acceptable one. The second algorithm is designed to assist the group in achieving a predefined consensus level. The main characteristics of our model are that: (1) it is independent of the prioritization method used in the consensus process; (2) it ensures that each individual multiplicative preference relation is of acceptable consistency when the predefined consensus level is achieved. Finally, some numerical examples are given to verify the effectiveness of our model.

Solvent induced shape recovery of shape memory polymer based on chemically cross-linked poly(vinyl alcohol)

Abstract: A shape memory polymer based on poly(vinyl alcohol) (SM-PVA) chemically cross-linked with glutaraldehyde exhibits good temperature responsive shape memory behavior. In the present investigation, solvent-induced shape memory behavior is observed by immersing this kind of SM-PVA in good or poor solvents (including water, DMF, and EG etc.) for PVA. A significant indication of shape memory is the decrease of the glass transition temperature (Tg), which is caused by PVA swelling in certain solvents. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), swelling equilibrium and bending tests are carried out to find the mechanism behind this interesting phenomenon. Factors that influence the permeation of solvents in the polymer depend on the rate and degree of swelling and whether swelling will occur, which determines the shape recovery ratio in different solvents. Water can induce shape recovery in a shorter time than organic solvents. The structure of water and PVA, and the interaction between them, contribute to the shorter recovery time. SM-PVA has an excellent shape recovery ratio even after several test cycles. Using solvents as a stimulus for shape memory behavior will extend applications of SMPs, especially in the field of medical devices, where stimulus instead of heat is highly desired.