Hsp70-Bag3 Module Regulates Macrophage Motility and Tumor Infiltration via Transcription Factor LITAF and CSF1

Area of Science:

• Molecular biology
• Cancer research
• Immunology

Background:

• The molecular chaperone Hsp70 and its co-chaperone Bag3 are involved in cancer development.
• Hsp70 influences cancer cell processes and macrophage tumor infiltration.
• The precise mechanisms by which Hsp70 affects macrophage functions remain unclear.

Purpose of the Study:

• To elucidate the molecular mechanisms underlying Hsp70's regulation of macrophage motility and tumor infiltration.
• To identify key proteins and pathways involved in this process.

Main Methods:

• Co-immunoprecipitation to identify protein interactions.
• Western blotting and quantitative PCR to assess protein and gene expression levels.
• Macrophage motility assays and chemokine level measurements.

Main Results:

• The Hsp70-bound co-chaperone Bag3 interacts with the transcription factor LITAF.
• The Hsp70-Bag3 complex controls LITAF expression by regulating its proteasomal and autophagy-dependent degradation.
• LITAF regulates the expression of the chemokine CSF1, which is crucial for macrophage motility.
• Silencing Bag3 or LITAF reduced macrophage motility, an effect reversed by adding CSF1.

Conclusions:

• A novel Hsp70-Bag3-LITAF-CSF1 pathway controlling macrophage motility and tumor infiltration has been identified.
• This pathway offers potential therapeutic targets for modulating immune cell behavior in cancer.