Acid‐sensing ion channels promote the inflammation and migration of cultured rat microglia

Abstract

Microglia, the major immune cells in central nervous system, act as the surveillance and scavenger of immune defense and inflammatory response. Previous studies suggest that there might be close relationship between acid-sensing ion channels (ASICs) and inflammation, however, the exact role of ASICs in microglia during inflammation remains elusive. In the present study, we identified the existence of ASICs in the primary cultured rat microglia and explored their functions. By using reverse transcriptase polymerase chain reaction (RT-PCR), quantitative real-time PCR (qPCR), western blotting, and immunofluorescence experiments, we demonstrated that ASIC1, ASIC2a, and ASIC3 were existed in cultured and in situ rat microglia. After lipopolysaccharide (LPS) stimulation, the expressions of microglial ASIC1 and ASIC2a were upregulated. Meanwhile, ASIC-like currents and acid-induced elevation of intracellular calcium were increased, which could be inhibited by the nonspecific ASICs antagonist amiloride and specific homomeric ASIC1a blocker PcTx1. In addition, both inhibitors reduced the expression of inflammatory cytokines, including inducible nitric oxide synthase and cyclooxygenase 2 stimulated by LPS. Furthermore, we also observed significant increase in the expression of ASIC1 and ASIC2a in scrape-stimulated microglial migration. Amiloride and PcTx1 prevented the migration by inhibiting ERK phosphorylation. Taken together, these results suggest that ASICs participate in neuroinflammatory response, which will provide a novel therapeutic strategy for controlling the inflammation-relevant neuronal diseases.

ASIC1 and ASIC3 contribute to acidity-induced EMT of pancreatic cancer through activating Ca2+/RhoA pathway

“…Transient receptor potential melastatin-like 7 induces EMT of breast cancer through a transient increased [Ca 2+ ]i, and attenuation of this channel reduces epidermal growth factor (EGF) and hypoxia-induced EMT. 39 Given that ASIC1 and ASIC3 can evoke Ca 2+ current and elevate [Ca 2+ ]i level of particular cells in acidification, 33, 40, 41, 42 we hypothesize that [Ca 2+ ]i acts as the second messenger, which mediates the acidity-induced EMT of pancreatic cancer. This study displayed that acidic pH e significantly increased [Ca 2+ ]i of pancreatic cancer cells in a pH-dependent manner, which was repressed by the inhibition of ASIC1 and ASIC3.…”

Multiple H+ sensors mediate the extracellular acidification-induced [Ca2+]i elevation in cultured rat ventricular cardiomyocytes

“…Methods were similar to our previous report with slightly modified3637. Primers used for RT-PCR analysis of all gene expressions were listed on Supplementary Table S1.…”

“…Membrane-bound primary antibodies were detected using proper secondary antibodies conjugated with horseradish peroxidase. Immunoblots were developed on films using the enhanced chemiluminescence technique3738 (SuperSignalWest Pico; Pierce Chemical Co., Rockford, IL, USA).…”

“…Ratio images (340/380 nm) were analyzed by TILLVISION 4.0 software. The amplitude of [Ca 2+ ] i transient (∆F) represented the difference between baseline concentration (F) and the transient peak response to the stimulation, and [Ca 2+ ] i response amplitude was defined as the normalized variations of [Ca 2+ ] i (∆F/F)3739.…”

MicroRNA-Let-7a regulates the function of microglia in inflammation

“…In response to any stimulus, microglia indicates a variety of responses that includes morphological alterations (Minten et al, 2012), migration to the site of injury (Jolivel et al, 2014;Yu et al, 2014), and increased expression of various factors such as cytokines (Kim et al, 2014;Skaper et al, 2014). Moreover, microglia transform into phagocytic cells; removing dead cells, protein aggregates, and viral pathogens (Hanisch and Kettenmann, 2007).…”