[Structure and function of PDGF-R-alpha and its expression in normal kidney and kidney diseases]

Platelet-derived growth factor is commonly known as a mitogen. Many research data suggest a role for PDGF-beta R in the mitogenic response of mesangial cells. There are four members of PDGF family known as PDGF-A chain, PDGF-B chain, PDGF-C chain and PDGF-D chain, which in active forms are dimers. As far as two receptors PDGF-alpha R and PDGF-beta R are known to bind PDGF. There is a difference in binding affinity of various forms of PDGF by these receptors. Two different promotors P1 and P2 can be used for PDGF-alpha R gene transcription. There are several different haplotypes of promotor P1 sequence. Transcription of PDGF-alpha R gene is under control of many factors. Interaction between a receptor and its ligand includes receptor dimerisation and autophosphorylation of tyrosine residues. PDGF AA is unique in that it can only be bound by alpha-receptor dimer. PDGF-AA expression has been confirmed in the normal kidney, as well as in several renal diseases. Although the expression of PDGF-alpha R has been found to accompany that of PDGF-AA, its actual relevance for the development of the glomerular pathology is not clear.