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Abstract: FR-PO748

Loss of FAM114A1 Attenuates Glomerular Injury by Preserving the Podocyte Cytoskeleton

Session Information

Category: Glomerular Diseases

  • 1401 Glomerular Diseases: Mechanisms, including Podocyte Biology

Authors

  • Hayashi, Norifumi, Kanazawa Ika Daigaku, Kahoku-gun, Ishikawa, Japan
  • Yokoyama, Hitoshi, Kanazawa Ika Daigaku, Kahoku-gun, Ishikawa, Japan
  • Furuichi, Kengo, Kanazawa Ika Daigaku, Kahoku-gun, Ishikawa, Japan
  • Beck, Laurence H., Boston University, Boston, Massachusetts, United States
Background

Transcriptomic analysis of microdissected human glomeruli has suggested novel molecular signatures associated with MN by revealing several genes differentially upregulated in MN compared to other glomerular diseases. We focused on a novel protein, Family with sequence similarity 114 member A1 (FAM114A1) that was identified as the top classifier gene in the dataset.

Methods

To detect exact localization of FAM114A1 in glomeruli, we applied immunofluorescence (IF) staining with normal human kidney specimens. Staining area was compared to determine if the expression of FAM114A1 increased at the protein level in human MN and rat passive Heymann nephritis (PHN). We knocked down FAM114A1 in cultured podocytes by siRNA transfection and conducted functional assays. We investigated protein structure of FAM114A1 in silico. To detect interacting proteins, affinity pulldown assay was performed using FAM114A1-3XFLAG protein and human glomerular extract. To determine the role of FAM114A1 in vivo, we analyzed Fam114a1 conventional knockout mice and conducted lipopolysaccharide (LPS) -induced albuminuria tests.

Results

IF studies showed the expression of FAM114A1 in the kidney was podocyte-specific and FAM114A1 mainly localized to podocyte primary and foot processes. The expression of FAM114A1 was increased in the human MN and rat PHN model. In cultured podocytes, FAM114A1 was colocalized with F-actin and adhesion molecules. Silencing FAM114A1 affected podocyte cytoskeletal development and podocyte cell migration. Affinity pulldown screening revealed that FAM114A1 interacts with several cytoskeleton-associated proteins. Mice lacking Fam114a1 displayed no overt proteinuria and histopathological abnormalities in glomeruli. However, the genetic loss of Fam114a1 attenuated albuminuria induced by LPS injury.

Conclusion

These findings suggest that glomerular injury can increase FAM114A1 expression which might promote podocyte cytoskeletal disruption. Loss of FAM114A1 could protect against glomerular injury by maintaining podocyte foot process structure.

Funding

  • NIDDK Support