Abstract: SA-PO299

The RNA Binding Protein Staufen2 Is Required to Maintain Integrity of the Golgi Apparatus and Podocyte Cell-Matrix Adhesion

Session Information

Category: Cell Biology

  • 204 Extracellular Matrix Biology, Fibrosis, Cell Adhesion

Authors

  • Harris, Jessica J., Boston Childrens Hospital, Boston, Massachusetts, United States
  • Schumacher, Valerie A., Childrens Hospital Boston, Boston, Massachusetts, United States
Background

Proper adhesion of podocytes to the glomerular basement membrane is necessary to withstand high transcapillary filtration pressure and to prevent glomerulosclerosis. Our preliminary data shows that the RNA binding protein Staufen2, known to mediate mRNA transport and local translation in neurons, is required for podocyte-matrix adhesion. In addition, we demonstrate that mice deficient in Staufen1 and 2 are more susceptible to glomerular disease, suggesting a role for local translation in the maintenance of the glomerular filtration barrier. The present study aims at determining the molecular mechanisms by which Staufen2 regulates cell-matrix adhesion.

Methods

A cell biological and biochemical approach was used to study the role of Staufen2 in the maintenance of cell-matrix adhesion.

Results

The most critical cell-matrix adhesion receptor in podocytes is a3b1 integrin, which bridges laminin 521 in the GBM to the intracellular actin cytoskeleton. We show that glycosylation of integrin β1 is altered in Staufen2 knockdown immortalized podocytes and that there is decreased phosphorylation of the b1 integrin effectors Src tyrosine kinase and focal adhesion kinase (FAK). Specifically, complex-type N-glycans added to b1 integrin in the Golgi apparatus by glucosaminyltransferases Gnt-III and V were decreased in Staufen2 knockdown cells. Both corresponding mRNAs were found to be bound and stabilized by Staufen2, suggesting a role for Staufen2 in regulating complex-type glycosylation. In addition, the Golgi apparatus was severely fragmented in Staufen2 knockdown podocytes, especially following mechanical stretch. This coincided with an increase in F-actin, known to cause Golgi fragmentation.

Conclusion

Staufen2 mediated morphological and functional integrity of the Golgi apparatus may represent a novel mechanism by which podocyte-matrix adhesion is maintained.

Funding

  • NIDDK Support