Advillin acts upstream of phospholipase C ϵ1 in steroid-resistant nephrotic syndrome

J Clin Invest. 2017 Dec 1;127(12):4257-4269. doi: 10.1172/JCI94138. Epub 2017 Oct 23.

Abstract

Steroid-resistant nephrotic syndrome (SRNS) is a frequent cause of chronic kidney disease. Here, we identified recessive mutations in the gene encoding the actin-binding protein advillin (AVIL) in 3 unrelated families with SRNS. While all AVIL mutations resulted in a marked loss of its actin-bundling ability, truncation of AVIL also disrupted colocalization with F-actin, thereby leading to impaired actin binding and severing. Additionally, AVIL colocalized and interacted with the phospholipase enzyme PLCE1 and with the ARP2/3 actin-modulating complex. Knockdown of AVIL in human podocytes reduced actin stress fibers at the cell periphery, prevented recruitment of PLCE1 to the ARP3-rich lamellipodia, blocked EGF-induced generation of diacylglycerol (DAG) by PLCE1, and attenuated the podocyte migration rate (PMR). These effects were reversed by overexpression of WT AVIL but not by overexpression of any of the 3 patient-derived AVIL mutants. The PMR was increased by overexpression of WT Avil or PLCE1, or by EGF stimulation; however, this increased PMR was ameliorated by inhibition of the ARP2/3 complex, indicating that ARP-dependent lamellipodia formation occurs downstream of AVIL and PLCE1 function. Together, these results delineate a comprehensive pathogenic axis of SRNS that integrates loss of AVIL function with alterations in the action of PLCE1, an established SRNS protein.

Keywords: Monogenic diseases; Nephrology.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Actin-Related Protein 2-3 Complex / genetics
  • Actin-Related Protein 2-3 Complex / metabolism
  • Cell Movement / genetics
  • Diglycerides / genetics
  • Diglycerides / metabolism
  • Female
  • Humans
  • Male
  • Microfilament Proteins* / genetics
  • Microfilament Proteins* / metabolism
  • Mutation*
  • Nephrotic Syndrome / congenital*
  • Nephrotic Syndrome / genetics
  • Nephrotic Syndrome / metabolism
  • Nephrotic Syndrome / pathology
  • Phosphoinositide Phospholipase C* / genetics
  • Phosphoinositide Phospholipase C* / metabolism
  • Podocytes* / metabolism
  • Podocytes* / pathology
  • Pseudopodia* / genetics
  • Pseudopodia* / metabolism

Substances

  • AVIL protein, human
  • Actin-Related Protein 2-3 Complex
  • Diglycerides
  • Microfilament Proteins
  • Phosphoinositide Phospholipase C
  • phospholipase C epsilon

Supplementary concepts

  • Nephrotic syndrome, idiopathic, steroid-resistant