Role of TLR4 in endoplasmic reticulum stress induced by physical exercise in skeletal muscle

• Grant number: 20/04269-8
• Support Opportunities: Scholarships in Brazil - Master
• Start date: January 01, 2021
• End date: May 31, 2022
• Field of knowledge: Health Sciences - Physical Education
• Principal Investigator: Adelino Sanchez Ramos da Silva
• Grantee: Bruno Brieda Marafon
• Host Institution: Escola de Educação Física e Esporte de Ribeirão Preto (EEFERP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil

Abstract

Inflammation leads to endoplasmic reticulum (ER) stress, as well as the practice of acute (APE) and chronic physical exercise (CPE). However, there are still no data in the literature regarding the functions of TLR4 in ER stress during exercise. Therefore, the aim of the study is to verify the responses of markers of ER stress in TLR4 knockout (KO) mice and wild-type (WT) mice after acute and chronic physical exercise. 25 C57BL/6 Tlr4wt/wt male mice and 25 Tlr4-/- mice with 8 weeks of life were used. The animals were kept in polyethylene cages in trios, with controlled temperature (22 ± 2 ° C), inverted light-dark cycle (12:12h), with free access to food and water. The animals were separated into three groups for the acute physical exercise session (APE): control (sedentary mice), moderate (moderate physical exercise) and intense (intense physical exercise); and in two groups for the chronic training protocol (CPE): control (sedentary mice), trained (training protocol). The assessment of the physical performance of the mice occurred 48 hours before and after the CPE protocol, and consisted of the rotarod test, incremental load test, and exhaustive test. Two hours after performing the EFA protocols, and one week after the end of the CPE protocol, the animals were anesthetized and the skeletal muscles (gastrocnemius) were removed, isolated and stored in the freezer at -80°C for subsequent analysis of the gene expression using the Real Time-Polymerase Chain Reaction (RTq-PCR) and protein analysis using the Western blot technique. The results so far (APE) show that the TLR4 KO mice achieved a significantly lower speed than the WT group, as well as the Pmax-adjusted speed of 75%. There was no statistical difference between WT and KO mice at baseline for any of the verified proteins. The BiP chaperone showed a drop in KO mice after physical exercise regardless of intensity, when compared to the WT group (p <0.05). Observing Caspase3 responses in the KO group, there was a significant increase in this protein after intense exercise, when compared to moderate exercise. There was also a difference between the animals' genotypes for intense exercise, where Caspase3 was more expressed in KO mice. In conclusion, the lack of TLR4 seems to affect the availability of BiP during ER stress induced by APE, as well as leading to increased activation of Caspase 3, a protein related to cell apoptosis. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

DE VICENTE, LARISSA G.; MUNOZ, VITOR R.; PINTO, ANA P.; ROVINA, RAFAEL L.; DA ROCHA, ALISSON L.; MARAFON, BRUNO B.; DE A TAVARES, MARIA EDUARDA; TEIXEIRA, GIOVANA R.; FERRARI, GUSTAVO D.; ALBERICI, LUCIANE C.; et al. TLR4 deletion increases basal energy expenditure and attenuates heart apoptosis and ER stress but mitigates the training-induced cardiac function and performance improvement. Life Sciences, v. 285, NOV 15 2021. (20/04269-8, 17/09038-1)

MARAFON, BRUNO B.; PINTO, ANA P.; ROPELLE, EDUARDO R.; DE MOURA, LEANDRO P.; CINTRA, DENNYS E.; PAULI, JOSE R.; DA SILVA, ADELINO S. R.. Muscle endoplasmic reticulum stress in exercise. ACTA PHYSIOLOGICA, v. 235, n. 1, p. 13-pg., 2022-02-21. (21/08693-1, 20/04269-8, 19/11820-5)

MARAFON, BRUNO B.; PINTO, ANA P.; DE VICENTE, LARISSA G.; DA ROCHA, ALISSON L.; SIMABUCO, FERNANDO M.; ROPELLE, EDUARDO R.; DE MOURA, LEANDRO P.; CINTRA, DENNYS E.; PAULI, JOSE R.; DA SILVA, ADELINO S. R.. Genetic ablation of Toll-like Receptor 4 seems to activate the apoptosis pathway in the skeletal muscle of mice after acute physical exercise. Cell Biochemistry and Function, v. N/A, p. 12-pg., 2022-11-22. (20/13443-1, 20/04269-8, 19/11820-5, 21/06291-3)

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

MARAFON, Bruno Brieda. Role of TLR4 in endoplasmic reticulum stress induced by physical exercise in skeletal muscle. 2022. Master's Dissertation - Universidade de São Paulo (USP). Escola de Educação Física e Esporte de Ribeirão Preto (EEFERP) Ribeirão Preto.