Recombinant Semliki Forest virus for over-expression and pharmacological characterisation of the histamine H-2 receptor in mammalian cells

We describe the use of recombinant Semliki Forest virus (SFV) vectors for e fficient expression of the rat histamine H-2 (rH(2)) receptor in COS-7 (Afr ican green monkey kidney cells) cells. Recombinant SFV-infected COS-7 cells express the histamine rH(2) receptor in a time-dependent fashion with a ma ximum expression level of 50 pmol mg(-1) after 40 h. SFV-mediated histamine rH(2) receptor expression shows similar pharmacological properties as the receptor expressed transiently or stably in mammalian cells. In addition, w e demonstrate the pharmacological and functional characterisation of the (D N)-N-115 mutated histamine rH(2) receptor. It has been shown that the (DN)- N-115 mutation renders the receptor constitutively active and structurally unstable. The rapid onset of and high maximal expression levels obtained fr om SFV-infected COS-7 cells enabled us to characterise this mutant receptor . We prove that recombinant SFV vectors are powerful tools for heterologous expression of G-protein-coupled receptors and that one can achieve both th e high-level gene expression described for baculovirus-infected insect cell s and the use of mammalian cells as hosts. (C) 2001 Elsevier Science B.V. A ll rights reserved.