The Interaction between GFAP and Fascin in U343 Glioma Cell Line

Objective : Glial fibrillary acidic protein (GFAP) is a 50kDa intermediate filament protein that acts as a specific marker for filial cell differentiation. And GFAP has a role in maintaining cytoskeletal architecture and shape. We hypothesize that GFAP supports cytoskeletal integrity in glial cells by key interactions with intermidiate filament associated protein(IFAP). Our study aims to characterize this interaction between these molecules in detail and determine its physiological relevance in glial cells. Methods : To isolate IFAP that bind to GFAP, we screened a human fetal brain cDNA library using the yeast two-hybrid assay. The interaction screen resulted in a number of positive interacting clones which were subjected to DNA sequence analysis and their identities were determined by Gen Bank Basic Local Alignment Search Tool(BLAST) searching. Results : One of the GFAP-binding proteins isolated encodes an actin-bundling protein called fascin. Fascin is a well-characterized protein tha: functions to organize filamentous actin into packed bundles. We confirmed the GFAP-fascin interaction by coimmunoprecipitation analyses in the U343 glioma cell line. Immunolocalization studies demonstrated GFAP and fascin colocalized in normal astrocytes, glioma cell lines, and glioma tumour specimens. Furthermore, ultrastructural electron microscopy data demonstrated an association between GFAP and fascin. Specifically, there was colocalization within astrccytic processes and cellular protrusions. Conclusion : The colocalization of GFAP and fascin suggests that this interaction is important in glial cell architecture and stability. Additional studies are underway to evaluate the function and importance of this interaction in glial cells.ope