DMSO Enhances TGF-β Activity by Recruiting the Type II TGF-β Receptor From Intracellular Vesicles to the Plasma Membrane

Dimethyl sulfoxide (DMSO) is used to treat many diseases/symptoms. The molecular basis of the pharmacological actions of DMSO has been unclear. We hypothesized that DMSO exerts some of these actions by enhancing TGF-beta activity. Here we show that DMSO enhances TGF-beta activity by similar to 3-4-fold in Mv1Lu and NMuMG cells expressing Smad-dependent luciferase reporters. In Mv1Lu cells, DMSO enhances TGF-beta-stimulated expression of P-Smad2 and PAI-1. It increases cell-surface expression of TGF-beta receptors (T beta R-I and/or T beta R-II) by similar to 3-4-fold without altering their cellular levels as determined by I-125-labeled TGF-beta-cross-linking/Western blot analysis, suggesting the presence of large intracellular pools in these cells. Sucrose density gradient ultracentrifugation/Western blot analysis reveals that DMSO induces recruitment of T beta R-II (but not T beta R-I) from its intracellular pool to plasma-membrane microdomains. It induces more recruitment of T beta R-II to non-lipid raft microdomains than to lipid rafts/caveolae. Mv1Lu cells transiently transfected with T beta R-II-HA plasmid were treated with DMSO and analyzed by indirect immunofluoresence staining using anti-HA antibody. In these cells, T beta R-II-HA is present as a vesicle-like network in the cytoplasm as well as in the plasma membrane. DMSO causes depletion of T beta R-II-HA-containing vesicles from the cytoplasm and co-localization of T beta R-II-HA and cveolin-1 at the plasma membrane. These results suggest that DMSO, a fusogenic substance, enhances TGF-beta activity presumably by inducing fusion of cytoplasmic vesicles (containing T beta R-II) and the plasma membrane, resulting in increased localization of T beta R-II to non-lipid raft microdomains where canonical signaling occurs. Fusogenic activity of DMSO may play a pivotal role in its pharmacological actions involving membrane proteins with large cytoplasmic pools. (C) 2015 Wiley Periodicals, Inc.