Activating transcription factor 3 (ATF3) promotes sublytic C5b-9-induced glomerular mesangial cells apoptosis through up-regulation of Gadd45α and KLF6 gene expression.

The sublytic C5b-9 complexes can result in glomerular mesangial cells (GMCs) apoptosis, which involved in the initiation and development of rat Thy-1 nephritis. Activating transcription factor 3 (ATF3) is an immediate early gene for cells to cope with a variety of stress signals, and our previous study revealed that ATF3 could promote GMCs apoptosis attacked by sublytic C5b-9. But the mechanism of ATF3 promoting GMCs apoptosis triggered by sublytic C5b-9 attack has not been elucidated. In this study, the data showed that the expression of ATF3, growth arrest and DNA damage-45 alpha (Gadd45α), Krüppel-like factor 6 (KLF6) and proliferating cell nuclear antigen (PCNA) in the GMCs in response to sublytic C5b-9 stimulation for the indicated time was significantly increased, and ATF3 expression could lead to GMCs apoptosis through up-regulation of Gadd45α and KLF6, but not up-regulation of PCNA. Furthermore, Gadd45α was identified as a downstream target gene regulated by ATF3 directly, and KLF6 might be regulated by ATF3 in an indirect manner.