title: DNA damage is a novel response to sublytic complement C5b-9-induced injury in podocytes.
abstract: In response to Ab-complement-mediated injury, podocytes can undergo lysis, apoptosis, or, when exposed to sublytic (<5% lysis) amounts of C5b-9, become activated. Following the insertion of sublytic quantities of C5b-9, there is an increase in signaling pathways and growth factor synthesis and release of proteases, oxidants, and other molecules. Despite an increase in DNA synthesis, however, sublytic C5b-9 is associated with a delay in G(2)/M phase progression in podocytes. Here we induced sublytic C5b-9 injury in vitro by exposing cultured rat podocytes or differentiated postmitotic mouse podocytes to Ab and a complement source; we also studied the passive Heymann nephritis model of experimental membranous nephropathy in rats. A major finding was that sublytic C5b-9-induced injury caused an increase in DNA damage in podocytes both in vitro and in vivo. This was associated with an increase in protein levels for p53, the CDK inhibitor p21, growth-arrest DNA damage-45 (GADD45), and the checkpoint kinases-1 and -2. Sublytic C5b-9 increased extracellular signal-regulated kinase-1 and -2 (ERK-1 and -2), and inhibiting ERK-1 and -2 reduced the increase in p21 and GADD45 and augmented the DNA damage response to sublytic C5b-9-induced injury. These results show that sublytic C5b-9 induces DNA damage in vitro and in vivo and may explain why podocyte proliferation is limited following immune-mediated injury.
authors.affiliation: Department of Medicine, Division of Nephrology, University of Washington, Seattle, Washington 98195, USA.
authors.forename: Jeffrey W
authors.initials: JW
authors.lastname: Pippin
authors.forename: Raghu
authors.initials: R
authors.lastname: Durvasula
authors.forename: Arndt
authors.initials: A
authors.lastname: Petermann
authors.forename: Keiju
authors.initials: K
authors.lastname: Hiromura
authors.forename: William G
authors.initials: WG
authors.lastname: Couser
authors.forename: Stuart J
authors.initials: SJ
authors.lastname: Shankland
mesh_terms: D000818:Animals; D017209:Apoptosis; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D015938:Complement Membrane Attack Complex / Q000494:pharmacology*; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000096:biosynthesis; D004249:DNA Damage; D004847:Epithelial Cells / Q000473:pathology; D005920:Glomerular Mesangium / Q000473:pathology; D047908:Intracellular Signaling Peptides and Proteins; D007678:Kidney Glomerulus / Q000473:pathology*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology; D014176:Protein Biosynthesis; D011494:Protein Kinases / Q000096:biosynthesis; D017346:Protein Serine-Threonine Kinases; D011506:Proteins; D051381:Rats; D016159:Tumor Suppressor Protein p53 / Q000032:analysis; D000097642:GADD45 Proteins
chemical_list: D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D015938:Complement Membrane Attack Complex; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D047908:Intracellular Signaling Peptides and Proteins; D020928:Mitogen-Activated Protein Kinases; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011506:Proteins; D016159:Tumor Suppressor Protein p53; D000097642:GADD45 Proteins; C493957:Cdkn1a protein, mouse; C493958:Cdkn1a protein, rat; C578633:Chek2 protein, mouse; C578632:Chek2 protein, rat