Cloning and characterization of dominant negative splice variants of the human histamine H4 receptor.
The H(4)R (histamine H(4) receptor) is the latest identified member of the histamine receptor subfamily of GPCRs (G-protein-coupled receptors) with potential functional implications in inflammatory diseases and cancer. The H(4)R is primarily expressed in eosinophils and mast cells and has the highest homology with the H(3)R. The occurrence of at least twenty different hH(3)R (human H(3)R) isoforms led us to investigate the possible existence of H(4)R splice variants. In the present paper, we report on the cloning of the first two alternatively spliced H(4)R isoforms from CD34+ cord blood-cell-derived eosinophils and mast cells. These H(4)R splice variants are localized predominantly intracellularly when expressed recombinantly in mammalian cells. We failed to detect any ligand binding, H(4)R-ligand induced signalling or constitutive activity for these H(4)R splice variants. However, when co-expressed with full-length H(4)R [H(4)R((390)) (H(4)R isoform of 390 amino acids)], the H(4)R splice variants have a dominant negative effect on the surface expression of H(4)R((390)). We detected H(4)R((390))-H(4)R splice variant hetero-oligomers by employing both biochemical (immunoprecipitation and cell-surface labelling) and biophysical [time-resolved FRET (fluorescence resonance energy transfer)] techniques. mRNAs encoding the H(4)R splice variants were detected in various cell types and expressed at similar levels to the full-length H(4)R((390)) mRNA in, for example, pre-monocytes. We conclude that the H(4)R splice variants described here have a dominant negative effect on H(4)R((390)) functionality, as they are able to retain H(4)R((390)) intracellularly and inactivate a population of H(4)R((390)), presumably via hetero-oligomerization.
van Rijn
Richard M
RM
Leiden/Amsterdam Center for Drug Research, Department of Medicinal Chemistry, Vrije Universiteit Amsterdam, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.
van Marle
André
A
Chazot
Paul L
PL
Langemeijer
Ellen
E
Qin
Yongjun
Y
Shenton
Fiona C
FC
Lim
Herman D
HD
Zuiderveld
Obbe P
OP
Sansuk
Kamonchanok
K
Dy
Michel
M
Smit
Martine J
MJ
Tensen
Cornelis P
CP
Bakker
Remko A
RA
Leurs
Rob
R
D000595:Amino Acid Sequence; D000818:Animals; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D005312:Fetal Blood / Q000737:chemistry / Q000166:cytology / Q000378:metabolism; D014644:Genetic Variation; D018922:HL-60 Cells; D006801:Humans; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics*; D043562:Receptors, G-Protein-Coupled / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics*; D011968:Receptors, Histamine / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics*; D000074040:Receptors, Histamine H4
C418607:HRH4 protein, human; D020033:Protein Isoforms; D043562:Receptors, G-Protein-Coupled; D011968:Receptors, Histamine; D000074040:Receptors, Histamine H4