6O31

CRYSTAL STRUCTURE OF THE ACTIN-BINDING DOMAIN OF HUMAN ALPHA-ACTININ-4


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.51 Å
  • R-Value Free: 0.254 
  • R-Value Work: 0.208 
  • R-Value Observed: 0.211 

Starting Model: experimental
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wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Phosphorylation of ACTN4 Leads to Podocyte Vulnerability and Proteinuric Glomerulosclerosis.

Feng, D.Kumar, M.Muntel, J.Gurley, S.B.Birrane, G.Stillman, I.E.Ding, L.Wang, M.Ahmed, S.Schlondorff, J.Alper, S.L.Ferrante, T.Marquez, S.L.Ng, C.F.Novak, R.Ingber, D.E.Steen, H.Pollak, M.R.

(2020) J Am Soc Nephrol 31: 1479-1495

  • DOI: https://doi.org/10.1681/ASN.2019101032
  • Primary Citation of Related Structures:  
    6O31, 6OA6

  • PubMed Abstract: 

    Genetic mutations in α -actinin-4 (ACTN4)-an important actin crosslinking cytoskeletal protein that provides structural support for kidney podocytes-have been linked to proteinuric glomerulosclerosis in humans. However, the effect of post-translational modifications of ACTN4 on podocyte integrity and kidney function is not known. Using mass spectrometry, we found that ACTN4 is phosphorylated at serine (S) 159 in human podocytes. We used phosphomimetic and nonphosphorylatable ACTN4 to comprehensively study the effects of this phosphorylation in vitro and in vivo . We conducted x-ray crystallography, F-actin binding and bundling assays, and immunofluorescence staining to evaluate F-actin alignment. Microfluidic organ-on-a-chip technology was used to assess for detachment of podocytes simultaneously exposed to fluid flow and cyclic strain. We then used CRISPR/Cas9 to generate mouse models and assessed for renal injury by measuring albuminuria and examining kidney histology. We also performed targeted mass spectrometry to determine whether high extracellular glucose or TGF- β levels increase phosphorylation of ACTN4. Compared with the wild type ACTN4, phosphomimetic ACTN4 demonstrated increased binding and bundling activity with F-actin in vitro . Phosphomimetic Actn4 mouse podocytes exhibited more spatially correlated F-actin alignment and a higher rate of detachment under mechanical stress. Phosphomimetic Actn4 mice developed proteinuria and glomerulosclerosis after subtotal nephrectomy. Moreover, we found that exposure to high extracellular glucose or TGF- β stimulates phosphorylation of ACTN4 at S159 in podocytes. These findings suggest that increased phosphorylation of ACTN4 at S159 leads to biochemical, cellular, and renal pathology that is similar to pathology resulting from human disease-causing mutations in ACTN4. ACTN4 may mediate podocyte injury as a consequence of both genetic mutations and signaling events that modulate phosphorylation.


  • Organizational Affiliation

    Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts dfeng@bidmc.harvard.edu mpollak@bidmc.harvard.edu.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Alpha-actinin-4234Homo sapiensMutation(s): 0 
Gene Names: ACTN4
UniProt & NIH Common Fund Data Resources
Find proteins for O43707 (Homo sapiens)
Explore O43707 
Go to UniProtKB:  O43707
PHAROS:  O43707
GTEx:  ENSG00000130402 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupO43707
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.51 Å
  • R-Value Free: 0.254 
  • R-Value Work: 0.208 
  • R-Value Observed: 0.211 
  • Space Group: P 41 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 38.069α = 90
b = 38.069β = 90
c = 302.655γ = 90
Software Package:
Software NamePurpose
REFMACrefinement
HKL-2000data reduction
HKL-2000data scaling
PHASERphasing

Structure Validation

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Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Disease (NIH/NIDDK)United StatesDK59588
National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Disease (NIH/NIDDK)United StatesDK114329
National Institutes of Health/National Institute of Diabetes and Digestive and Kidney Disease (NIH/NIDDK)United StatesDK007199

Revision History  (Full details and data files)

  • Version 1.0: 2020-02-26
    Type: Initial release
  • Version 1.1: 2020-09-09
    Changes: Database references
  • Version 1.2: 2023-10-11
    Changes: Data collection, Database references, Refinement description