Opposing FlnA and FlnB interactions regulate RhoA activation in guiding dynamic actin stress fiber formation and cell spreading.

Filamins are a family of actin-binding proteins responsible for diverse biological functions in the context of regulating actin dynamics and vesicle trafficking. Disruption of these proteins has been implicated in multiple human developmental disorders. To investigate the roles of different filamin isoforms, we focused on FlnA and FlnB interactions in the cartilage growth plate, since mutations in both molecules cause chondrodysplasias. Current studies show that FlnA and FlnB share a common function in stabilizing the actin cytoskeleton, they physically interact in the cytoplasm of chondrocytes, and loss of FlnA enhances FlnB expression of chondrocytes in the growth plate (and vice versa), suggesting compensation. Prolonged FlnB loss, however, promotes actin-stress fiber formation following plating onto an integrin activating substrate whereas FlnA inhibition leads to decreased actin formation. FlnA more strongly binds RhoA, although both filamins overlap with RhoA expression in the cell cytoplasm. FlnA promotes RhoA activation whereas FlnB indirectly inhibits this pathway. Moreover, FlnA loss leads to diminished expression of ß1-integrin, whereas FlnB loss promotes integrin expression. Finally, fibronectin mediated integrin activation has been shown to activate RhoA and activated RhoA leads to stress fiber formation and cell spreading. Fibronectin stimulation in null FlnA cells impairs enhanced spreading whereas FlnB inhibited cells show enhanced spreading. While filamins serve a primary static function in stabilization of the actin cytoskeleton, these studies are the first to demonstrate a dynamic and antagonistic relationship between different filamin isoforms in the dynamic regulation of integrin expression, RhoGTPase activity and actin stress fiber remodeling.

Knowledge, attitude, and practice toward regenerative endodontics and factors affecting its practice among dental practitioners in Ajmer city: A cross-sectional study.

BACKGROUND: Regenerative methods, which regenerate the damaged structures, are one of the treatment methods in endodntics. This conservative approach helps to generate cells that may produce the lost structure. Thus, the aim of this study was to explore the knowledge, attitude, and practice among dental practitioners toward regenerative endodontics and factors affecting their knowledge, attitude, and practice. MATERIALS AND METHODS: It was a cross-sectional questionnaire study conducted in the month of June-August 2018 in Ajmer city. Permission to conduct the study was obtained from JLN Medical College and Hospital, Department of Dentistry. A total of 100 clinics were visited and face-to-face interview schedule was conducted. A total of 123 dental practitioners were interviewed. A 26 item questionnaire was generated to measure knowledge, attitude, and practice of dental professionals regarding regenerative endodontics. RESULTS: 63% of study participants had poor knowledge scores. Majority of study participants 83 (67%) had poor attitude scores. On applying Pearson's correlation, it was determined that the knowledge regarding regenerative endodontics was significantly (P ≤ 0.001) ** correlated to the attitude among study participants. On applying Chi-square test, it was assessed that the knowledge and practice among study participants were significantly (P = 0.041*) and (P = 0.001**) associated with gender of study participants. CONCLUSION: From above results, it is concluded that study participants have poor knowledge, attitude, and practice regarding regenerative endodontics. The knowledge regarding regenerative endodontics was significantly associated with the attitude of study participants. Participants with Masters of Dental Surgery (MDS) degree had a significant effect on the knowledge regarding the regenerative endodontics. Endodontic specialty has a significant effect on the attitude of study subjects.