Expression of Fc alpha/mu receptor by human mesangial cells: a candidate receptor for immune complex deposition in IgA nephropathy.
IgA nephropathy is characterized by the deposition of IgA immune complexes in the glomerular mesangium, but the mechanisms responsible for this are not well understood. Human mesangial cells (HMCs) can bind IgA but do not express known IgA receptors. We show here that primary HMCs express mRNA for a novel receptor, the Fc alpha/mu receptor (Fcalpha/muR), and that receptor expression is upregulated by IL-1. We also detected mRNA for a novel receptor variant in HMCs that may encode a soluble form of the receptor. Fcalpha/muR was expressed in a heterologous system which showed that the receptor was approximately 58 kDa in weight and was only minimally N-glycosylated. As predicted from the characteristics of the murine homologue, the expressed human Fcalpha/muR was able to bind IgA and IgM, but not IgG. These results suggest that Fcalpha/muR may be the receptor responsible for mesangial IgA deposition in IgA nephropathy.
McDonald
Kenneth J
KJ
Renal Unit, Western Infirmary, Dumbarton Road, Glasgow G11 6NT, Scotland, United Kingdom. k.j.mcdonald@clinmed.gla.ac.uk
Cameron
Angus J M
AJ
Allen
Janet M
JM
Jardine
Alan G
AG
D017398:Alternative Splicing; D000818:Animals; D015703:Antigens, CD / Q000096:biosynthesis*; D019556:COS Cells; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D005920:Glomerular Mesangium / Q000166:cytology / Q000378:metabolism*; D005922:Glomerulonephritis, IGA / Q000378:metabolism*; D006801:Humans; D007070:Immunoglobulin A / Q000378:metabolism; D007074:Immunoglobulin G / Q000378:metabolism; D007075:Immunoglobulin M / Q000378:metabolism; D008024:Ligands; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011485:Protein Binding; D011961:Receptors, Fc / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction
D015703:Antigens, CD; D018076:DNA, Complementary; C036832:Fc(alpha) receptor; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D008024:Ligands; D011961:Receptors, Fc; C035311:immunoglobulin M receptor