Transgenic Research

, Volume 19, Issue 2, pp 285–289

Mice with podocyte-specific overexpression of wild type α-actinin-4 are healthy controls for K256E-α-actinin-4 mutant transgenic mice

  • Jean-Louis Michaud
  • Erin Stitt-Cavanaugh
  • Nicole Endlich
  • Karlhans Endlich
  • Yves De Repentigny
  • Rashmi Kothary
  • Chris R. J. Kennedy
Brief Communication

Abstract

Mutations in the gene ACTN4 encoding the actin bundling protein—α-actinin-4 underlie an inherited form of kidney lesions known as focal segmental glomerulosclerosis (FSGS). Previously, we developed a model for this condition by generating mice with podocyte-specific overexpression of a disease-causing mutant α-actinin-4 (K256E-ACTN4pod+). However, whether α-actinin-4 overexpression artifacts and not the gain of affinity effects of the mutation accounted for the robust FSGS phenotype in these mice was unclear. To address this question, we developed a control line of mice with podocyte-specific overexpression of wildtype α-actinin-4 (wt-ACTN4pod+). An 8.3 kb fragment of the mouse nephrin promoter (NPHS1) was used to drive expression of a hemagglutinin (HA)-tagged wildtype α-actinin-4 coding sequence in mice. Five founder lines expressing the HA-tagged α-actinin-4 protein in a podocyte-specific manner were obtained, as determined by co-immunofluorescence with HA and synaptopodin antibodies. Quantitative PCR revealed that renal transgene mRNA levels of wt-ACTN4pod+ mice are similar to K256E-ACTN4pod+ mice. In contrast to K256E-ACTN4pod+ mice which exhibit albuminuria, podocyte foot process effacement and glomerular scarring, wt-ACTN4pod+ mice are healthy and indistinguishable from non-transgenic littermates. These findings suggest that the K256E mutation itself and not overexpression of α-actinin-4 protein per se accounts for the FSGS phenotype in our transgenic model.

Keywords

α-Actinin-4 Podocyte Glomerulosclerosis 

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Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  • Jean-Louis Michaud
    • 1
    • 2
  • Erin Stitt-Cavanaugh
    • 1
    • 2
  • Nicole Endlich
    • 3
  • Karlhans Endlich
    • 3
  • Yves De Repentigny
    • 1
  • Rashmi Kothary
    • 1
    • 2
  • Chris R. J. Kennedy
    • 1
    • 2
  1. 1.Kidney Research Centre, Division of Nephrology, Department of Medicine, Ottawa Health Research InstituteOttawa Hospital and University of OttawaOttawaCanada
  2. 2.Department of Cellular and Molecular MedicineUniversity of OttawaOttawaCanada
  3. 3.Department of Anatomy and Cell BiologyUniversity of GreifswaldGreifswaldGermany

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