Characterization of intermediate filaments in PC12 cells

Area of Science:

• Cell Biology
• Neuroscience
• Protein Biochemistry

Background:

• PC12 cells are a rat pheochromocytoma cell line widely used in neuroscience research.
• Intermediate filaments (IFs) are crucial cytoskeletal components involved in cellular structure and mechanical stability.
• Neurofilament triplet (NFT) proteins are specific to neurons and play a role in axonal development and maintenance.

Purpose of the Study:

• To identify and characterize the major polypeptide of intermediate filaments (IFs) in PC12 cells.
• To investigate the effect of nerve growth factor (NGF) on the expression and distribution of IFs and neurofilament triplet (NFT) proteins in PC12 cells.
• To determine if NGF induces a switch in IF polypeptide composition.

Main Methods:

• Isolation and purification of IF-enriched cytoskeletal preparations from PC12 cells.
• In vitro assembly of IFs from PC12 cytoskeletal preparations.
• Peptide mapping to compare proteins.
• Immunofluorescence microscopy using antibodies against the 57 kDa protein and NFT proteins.
• SDS-PAGE and immunoblotting to analyze polypeptide composition.

Main Results:

• A 57 kDa protein was identified as the major polypeptide in PC12 cell IFs, distinct from vimentin.
• NGF treatment led to changes in IF distribution, with arrays coursing through cytoplasm and neurites.
• NGF treatment increased the presence of NFT proteins and their filamentous structures in PC12 cells over time.
• The 57 kDa protein and NFT proteins were found to codistribute within PC12 cells.

Conclusions:

• PC12 cells possess intermediate filaments composed of a complex set of polypeptides, including a novel 57 kDa IF protein.
• NGF treatment influences the organization of IFs and promotes the expression of NFT proteins in PC12 cells.
• NGF stimulation does not result in a complete switch from mesenchymal IF polypeptide expression to NFT polypeptide expression.