Purpose: To evaluate the roles of CB1 cannabinoid receptors in cellular functions of trabecular meshwork (TM) cells, including cell migration, adhesion, morphology and cytoskeleton changes.
Methods: Noladin ether, a selective CB1 receptor agonist, and SR141716A, a selective CB1 receptor antagonist, were used to characterize the cellular functions of cultured porcine TM cells. Fluorescence assisted transmigration invasion and motility assays (FATIMA) were conducted to study TM cell migration using soluble fibronectin as a chemoattractant. Wound healing assays were used to further study TM cell migration. Standard cell adhesion assays of TM cells were performed on fibronectin-coated plates. In morphological studies, Alexafluor 488-labeled phalloidin staining was used to examine actin filaments, and immunocytochemistry using anti-paxillin antibodies was used to detect focal adhesions.
Results: In cell migration assays, CB1 agonist noladin ether at nanomolar ranges led to a concentration-dependent inhibition of migration of TM cells toward soluble fibronectin. CB1 antagonist SR141716A antagonized noladin ether-induced inhibition of migration of TM cells. In addition, noladin ether caused a delay in wound healing of confluent trabecular meshwork monolayers and this effect of noladin ether was antagonized by SR141716A. In cell adhesion assays, noladin ether treatment led to a moderate, but significant decrease of adhesion of TM cells to fibronectin-coated surface. This effect of noladin ether was concentration-dependent, and was antagonized by SR141716A. In morphological studies, noladin ether treatment caused rounding of TM cells in contrast to well-spread control TM cells. In addition, there was a reduction and fragmentation of actin stress fibers stained with Alexafluor 488-labeled phalloidin and a decrease of focal adhesions detected with an anti-paxillin antibody.
Conclusions: Noladin ether modulates the migration, adhesion, morphology, and actin cytoskeleton of TM cells. These effects of noladin ether are mediated through TM cell CB1 cannabinoid receptors.