cAMP-response element binding protein mediates podocyte injury in diabetic nephropathy by targeting lncRNA DLX6-AS1

Progressive proteinuria is one of the earliest clinical features of diabetic nephropathy (DN). In our previous study, lncRNA DLX6-AS1 (DLX6-AS1, Dlx6os1 in the mouse) was found to be associated with the extent of albuminuria in DN patients. Furthermore, the lack of Dlx6os1 was pivotal in switching off the inflammatory response in db/db mouse model. However, the regulatory factors responsible for elevated DLX6-AS1 in DN remains unknown.

To identify potential regulatory factors for DLX6-AS1, JASPAR database and DNA pull down combined subsequent liquid chromatography-tandem mass spectrometry were used. Dual-luciferase reporter assay and chromatin immunoprecipitation were then performed to confirm binding sites. We also investigated the effects of the regulatory factors on DN progression in db/db mouse model and cultured human podocytes.

Our analyses demonstrated that cAMP-response element binding protein (CREB) was highly expressed and closely associated with DLX6-AS1 in DN. In db/db mouse and in cultured podocytes, CREB silencing significantly reduced the level of DLX6-AS1 or Dlx6os1 and attenuated renal damage. Mechanistically, CREB overexpression aggravated renal inflammation and destroyed the structure of podocytes by targeting DLX6-AS1. The damaging role of CREB in podocyte injury was also inhibited by 666-15, a selective inhibitor, in a dose-dependent manner. In vivo, the inhibition of CREB by 666-15 significantly attenuated albuminuria and ameliorated inflammatory infiltration in podocytes.

Our findings indicated that CREB is a key mediator of podocyte injury and acts by regulating DLX6-AS1. Thus, CREB may be an effective and potential therapeutic target for the treatment of DN.