Cyclic mechanical stretch upregulates Akt, MAPK, and NF-kappaB signaling pathways in BV2 microglia

Abstract

Mild traumatic brain injury (mTBI) is prevalent in contact sports. Post injury, microglia in the central nervous system are known to produce an inflammatory response. Moreover, with repeated injuries, chronic inflammation may be sustained, which is detrimental to the host. This study focuses on the signaling pathways that are activated with brain injury-induced injury. We hypothesize that mechanical stretch activates inflammatory signaling pathways in microglia. This experiment utilized impulse, cyclic, and sham-stretch conditions in the presence or absence of the mechanosensitive channel inhibitor GSMTx4. Afterwards, the cell lysate was collected, and the samples were analyzed by a Luminex multiplexed ELISA to determine if there was a change in protein phosphorylation across 27 phosphoproteins in three main signaling pathways: Akt, MAPK, and NFkB. My data showed that GSMTx4 had little impact on phosphorylation, but it did increase the expression of the Akt pathway proteins. Nonetheless, the minimal role GSMTx4 played in the measured phospho-protein signaling pathways at acute timepoints could imply that Piezo1 does not play a direct role in acute pathway activation. Of note, however, a control 20% cyclic stretch resulted in an upregulation in phosphorylation in all signaling pathways. As such, future studies will include GSMTx4-treated BV2 microglia that undergo cyclic stretch at varying degrees. Clinically, this data is useful in understanding how sustained injury can force the progression of neurodegenerative diseases.