Integrin-linked kinase mediates bone morphogenetic protein 7-dependent renal epithelial cell morphogenesis

Area of Science:

• Developmental Biology
• Molecular Biology
• Cell Biology

Background:

• Bone morphogenetic protein 7 (BMP7) is known to stimulate renal branching morphogenesis.
• This process involves signaling pathways including p38 mitogen-activated protein kinase (p38(MAPK)) and activating transcription factor 2 (ATF-2).

Purpose of the Study:

• To investigate the novel role of integrin-linked kinase (ILK) in mediating renal epithelial cell morphogenesis.
• To identify p38(MAPK) as a target of ILK signaling in renal epithelial morphogenesis.

Main Methods:

• Utilized embryonic kidney explants and a cell culture model of renal epithelial morphogenesis.
• Employed adenovirus-mediated gene expression to manipulate ILK levels (wild-type and dominant-negative mutant).
• Assessed ILK kinase activity and phosphorylation of downstream targets (phospho-p38(MAPK), phospho-ATF-2) in response to BMP7 and ILK modulation.
• Used a specific p38(MAPK) inhibitor (SB203580) to determine the order of signaling events.

Main Results:

• ILK expression was spatially and temporally correlated with kidney branching morphogenesis.
• ILK overexpression stimulated ureteric bud branching, while dominant-negative ILK inhibited it.
• BMP7 increased ILK activity, and ILK overexpression enhanced BMP7-induced renal cell morphogenesis.
• ILK functions upstream of p38(MAPK) in the BMP7 signaling pathway, influencing phospho-p38(MAPK) and phospho-ATF-2 levels.

Conclusions:

• Integrin-linked kinase (ILK) plays a crucial role in mediating renal epithelial cell morphogenesis.
• ILK is a key component of the BMP7 signaling pathway, acting upstream of p38(MAPK) and ATF-2.
• This study elucidates a novel ILK-dependent signaling mechanism essential for kidney development.