Autophagy Modulators Profoundly Alter the Astrocyte Cellular Proteome.

Area of Science:

• Cellular Biology
• Molecular Biology
• Proteomics

Background:

• Autophagy is a fundamental cellular process for degradation and recycling, crucial for homeostasis and host defense.
• Pathogens exploit autophagy, and compounds like BafilomycinA1 (inducer) and Rapamycin (inhibitor) are used to study it.
• Known effects of these modulators target specific autophagy markers (e.g., LC3, p62).

Purpose of the Study:

• To investigate the global impact of autophagy modulators on host cell proteomes.
• To identify proteins affected by BafilomycinA1 and Rapamycin beyond established autophagy pathways.

Main Methods:

• U-251 astrocytic cells were treated with BafilomycinA1 and Rapamycin.
• Aptamer-based proteomic analysis (SOMAscan®) was employed to examine 1305 proteins.
• Complementary cytokine array analysis was performed on cell culture supernatants.

Main Results:

• Significant perturbations were observed in the U-251 astrocyte cellular proteome following drug treatment.
• Proteins involved in autophagy, such as cathepsins, were differentially regulated.
• Numerous proteins not previously linked to autophagy, including lactadherin and granulins, were significantly dysregulated, with some upregulated by both compounds.

Conclusions:

• BafilomycinA1 and Rapamycin exert profound and widespread effects on the cellular proteome.
• These commonly used autophagy modulators impact a broader range of cellular proteins than previously recognized.
• The findings necessitate a re-evaluation of the global cellular consequences when using these drugs to study autophagy.