DNA binding protein A (
DbpA) is a member of the human cold shock domain-containing
protein superfamily, with known functions in cell proliferation, differentiation, and stress responses.
DbpA mediates tight junction-associated activities in tubular epithelial cells, but the function of
DbpA in mesangial cells is unknown. Here, we found
DbpA protein expression restricted to vascular smooth muscle cells in healthy human kidney tissue but profound induction of
DbpA protein expression within the glomerular mesangial compartment in mesangioproliferative
nephritis. In vitro, depletion or overexpression of
DbpA using lentiviral constructs led to inhibition or promotion, respectively, of mesangial cell proliferation. Because
platelet-derived growth factor B (PDGF-B) signaling has a pivotal role in mesangial cell proliferation, we examined the regulatory effect of PDGF-B on
DbpA. In vitro studies of human and rat mesangial cells confirmed a stimulatory effect of PDGF-B on
DbpA transcript numbers and
protein levels. Additional in vivo investigations showed
DbpA upregulation in experimental rat anti-Thy1.1
nephritis and murine mesangioproliferative
nephritis models. To interfere with PDGF-B signaling, we injected nephritic rats with PDGF-B neutralizing aptamers or the
MEK/ERK inhibitor
U0126. Both interventions markedly decreased
DbpA protein expression. Conversely, continuous PDGF-B infusion in healthy rats induced
DbpA expression predominantly within the mesangial compartment. Taken together, these results indicate that
DbpA is a novel target of PDGF-B signaling and a key mediator of mesangial cell proliferation.