The RhoA/ROCK-I/MLC pathway is involved in the ethanol-induced apoptosis by anoikis in astrocytes

Anoikis is a programmed cell death induced by loss of anchorage that is involved in tissue homeostasis and disease. Ethanol is an important teratogen that induces marked central nervous system (CNS) dysfunctions. Here we show that astrocytes exposed to ethanol undergo morphological changes associated with anoikis, including the peripheral reorganization of both focal adhesions and actin-myosin system, cell contraction, membrane blebbing and chromatin condensation. We found that either the small GTPase RhoA or its effector ROCK-I (Rho kinase), promotes membrane blebbing in astrocytes. Ethanol induces a ROCK-I activation that is mediated by RhoA, rather than by caspase-3 cleavage. Accordingly, the RhoA inhibitor C3, completely abolishes the ethanol-induced ROCK-I activation. Furthermore, inhibition of both RhoA and ROCK prevents the membrane blebbing induced by ethanol. Ethanol also promotes myosin light chain (MLC) phosphorylation, which might be involved in the actin-myosin contraction. All of these findings strongly support that ethanol-exposed astrocytes undergo apoptosis by anoikis and also that the RhoA/ROCK-I/MLC pathway participates in this process.