Re-expression of Sall1 in podocytes protects against adriamycin-induced nephrosis

Lab Invest. 2017 Nov;97(11):1306-1320. doi: 10.1038/labinvest.2017.69. Epub 2017 Jul 31.

Abstract

The highly conserved spalt (sal) gene family members encode proteins characterized by multiple double zinc finger motifs of the C2H2 type. Humans and mice each have four known Sal-like genes (SALL1-4 in humans and Sall1-4 in mice). Sall1 is known to have a crucial role in kidney development. To explore the significance of Sall1 in differentiated podocytes, we investigated podocyte-specific Sall1-deficient mice (Sall1 KOp°d°/p°d°) using a podocin-Cre/loxP system and siRNA Sall1 knockdown (Sall1 KD) podocytes. Under physiological conditions, Sall1 KOp°d°/p°d° mice exhibited no proteinuria during their lifetime, but foot-process effacement was detected in some of the podocytes. To elucidate the role of Sall1 in injured podocytes, we used an adriamycin (ADR)-induced model of nephrosis and glomerulosclerosis. Surprisingly, the expression of Sall1 was elevated in control mice on day 14 after ADR injection. On day 28 after ADR injection, Sall1 KOp°d°/p°d° mice exhibited significantly higher levels of proteinuria and higher numbers of sclerotic glomeruli. Differentiated Sall1 KD podocytes showed a loss of synaptopodin, suppressed stress fiber formation, and, ultimately, impaired directed cell migration. In addition, the loss of Sall1 increased the number of apoptotic podocytes following ADR treatment. These results indicated that Sall1 has a protective role in podocytes; thus, we investigated the endoplasmic reticulum stress marker GRP78. GRP78 expression was higher in ADR-treated Sall1 KOp°d°/p°d° mice than in control mice. Sall1 appeared to influence the expression of GRP78 in injured podocytes. These results suggest that Sall1 is associated with actin reorganization, endoplasmic reticulum stress, and apoptosis in injured podocytes. These protective aspects of Sall1 re-expression in injured podocytes may have the potential to reduce apoptosis and possibly glomerulosclerosis.

MeSH terms

  • Actin Cytoskeleton / drug effects
  • Actin Cytoskeleton / metabolism
  • Actin Cytoskeleton / pathology
  • Animals
  • Antibiotics, Antineoplastic / adverse effects*
  • Apoptosis / drug effects
  • Biomarkers
  • Cell Line, Transformed
  • Cell Movement / drug effects
  • Crosses, Genetic
  • Doxorubicin / adverse effects*
  • Endoplasmic Reticulum Chaperone BiP
  • Endoplasmic Reticulum Stress / drug effects
  • Gene Expression Regulation / drug effects
  • Heat-Shock Proteins / genetics
  • Heat-Shock Proteins / metabolism
  • Kidney / drug effects*
  • Kidney / metabolism
  • Kidney / pathology
  • Mice, Knockout
  • Mice, Transgenic
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism
  • Nephrosis / chemically induced
  • Nephrosis / metabolism
  • Nephrosis / pathology
  • Nephrosis / prevention & control*
  • Podocytes / drug effects
  • Podocytes / metabolism*
  • Podocytes / pathology
  • RNA Interference
  • Recombinant Proteins / metabolism
  • Topoisomerase II Inhibitors / adverse effects*
  • Transcription Factors / antagonists & inhibitors
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*

Substances

  • Antibiotics, Antineoplastic
  • Biomarkers
  • Endoplasmic Reticulum Chaperone BiP
  • HSPA5 protein, human
  • Heat-Shock Proteins
  • Hspa5 protein, mouse
  • Microfilament Proteins
  • Recombinant Proteins
  • Sall1 protein, mouse
  • Synpo protein, mouse
  • Topoisomerase II Inhibitors
  • Transcription Factors
  • Doxorubicin