Muscarinic Receptors and BK Channels Are Affected by Lipid Raft Disruption of Salivary Gland Cells

Abstract

Activity-dependent fluid secretion is the most important physiological function of salivary glands and is regulated via muscarinic receptor signaling. Lipid rafts are important for G-protein coupled receptor (GPCR) signaling and ion channels in plasma membranes. However, it is not well understood whether lipid raft disruption affects all membrane events or only specific functions in muscarinic receptor-mediated water secretion in salivary gland cells. We investigated the effects of lipid raft disruption on the major membrane events of muscarinic transcellular water movement in human salivary gland (HSG) cells. We found that incubation with methyl-β-cyclodextrin (MβCD), which depletes lipid rafts, inhibited muscarinic receptor-mediated Ca2+ signaling in HSG cells and isolated mouse submandibular acinar cells. However, MβCD did not inhibit a Ca2+ increase induced by thapsigargin, which activates store-operated Ca2+ entry (SOCE). Interestingly, MβCD increased the activity of the large-conductance Ca2+-activated K+ channel (BK channel). Finally, we found that MβCD did not directly affect the translocation of aquaporin-5 (AQP5) into the plasma membrane. Our results suggest that lipid rafts maintain muscarinic Ca2+ signaling at the receptor level without directly affecting the activation of SOCE induced by intracellular Ca2+ pool depletion or the translocation of AQP5 into the plasma membrane.

Multifunctional Proximity Labeling Strategy for Lipid Raft-Specific Sialic Acid Tracking and Engineering

“…The specificity of lipid raft targeting was validated by the reduced fluorescent signal observed when cholesterol was depleted in cellular lipid rafts using methyl-β-cyclodextrin (MβCD) (Figure 2). 46 Additionally, we investigated the changes in CTxB-FITC binding after cells were treated with different concentrations of MβCD using CLSM. We found that CTxB-FITC binding to cells decreased with increasing MβCD concentration and reached a plateau at 100 μM (Figure S7).…”

Total glucosides of paeony alleviates experimental Sjögren's syndrome through inhibiting NLRP3 inflammasome activation of submandibular gland cells

“…There are some limitations to the interpretation of our results. First, in our study, mouse submandibular gland cells were prepared according to previous studies (46)(47)(48). The epithelium, fibroblasts were not able to be separated by this isolation method.…”