LASP1 mediates ADAM17 upregulation in high glucose to promote fibrosis in diabetic kidneys

Diabetic kidney disease (DKD), a prevalent complication of diabetes, is the leading cause of chronic kidney disease globally. The current standard of care cannot halt disease progression and thus new therapeutic targets are needed. We previously showed that the metalloprotease ADAM17 mediates the profibrotic response to high glucose in kidney mesangial cells. Its upregulation in high glucose conditions augments its profibrotic effects. Here we investigate regulation of the Adam17 promoter region -2304/-1567, previously shown to be glucose responsive, for which regulatory factors have not yet been identified.

Adam17 promoter regulation, cell surface translocation and activation were assessed in primary rat mesangial cells using standard molecular biology techniques. Type 1 diabetes was induced in mice using streptozocin and kidney function and development of fibrosis were assessed after 24 weeks. Human and mouse kidneys were immunostained for LASP1.

In rat mesangial cells, the LIM and SH3 protein 1 (LASP1) was identified as a regulator of the Adam17 promoter in response to high glucose by mass spectrometry of nuclear lysate proteins binding to the -2304/-1567 promoter region. Knockdown of LASP1 prevented glucose-induced Adam17 promoter activation and transcript and protein upregulation. LASP1 nuclear localisation and regulation of Adam17 promoter activity in high glucose required phosphorylation of LASP1 on S146 by protein kinase A, but not protein kinase G, and Y171 phosphorylation by Src kinase. LASP1 also regulated glucose-induced ADAM17 cell surface localisation and activation, dependent on its phosphorylation by Src and interaction with focal adhesion kinase. Profibrotic responses to glucose were inhibited by LASP1 downregulation. In vivo, LASP1 expression was increased in the kidneys of type 1 diabetic mice and in kidneys of patients with DKD. Mice with Lasp1 knockout showed attenuated development of DKD.

LASP1 regulates the synthesis and activation of ADAM17 in mesangial cells and is required for the profibrotic response to high glucose. Its deletion protects against DKD in mice. Targeting LASP1 may have therapeutic value as an indirect method of ADAM17 inhibition to inhibit fibrosis in DKD.