Native and cloned 5-HT(3A)(S) receptors are anchored to F-actin in clonal cells and neurons.

Using selective antibodies to visualize the short isoform of the 5-HT(3A) receptor, we report here that both native and cloned 5-HT(3A)(S) receptors formed clusters associated with F-actin in all cell types studied. NG 108-15 cells expressing native 5-HT(3A)(S) receptors, COS-7 cells transiently expressing 5-HT(3A)(S) subunits, and CHO cells stably transfected with a plasmid encoding the 5-HT(3A)(S) sequence all exhibited similar surface receptor topology with 5-HT(3A)(S) receptor cluster accumulation in F-actin-rich lamellipodia and microspikes. Colocalization and coclustering of 5-HT(3A)(S) subunits and F-actin were also observed in transfected hippocampal neurons. Treatment of the neurons with latrunculin-A, a compound altering F-actin polymerization, demonstrated that 5-HT(3A)(S) receptor cluster size and topology were dependent on F-actin integrity. These results suggest that the anchoring of 5-HT(3A)(S) receptor clusters to the cytoskeletal network probably plays a key role in the physiological regulation of the receptor topology and dynamics, as is the case for other members of the 4-TMD ion channel receptor family. (c) 2002 Elsevier Science (USA).