Caveolin-1 is an aggresome-inducing protein

Area of Science:

• Cell Biology
• Molecular Biology
• Protein Biochemistry

Background:

• Caveolin-1 (Cav1) forms caveolae, crucial for cellular processes like signaling and endocytosis.
• Aberrant Cav1 expression or mutations can cause mistrafficking and cellular dysfunction.
• Perinuclear accumulation of Cav1 has been previously, but incorrectly, associated with the Golgi complex.

Purpose of the Study:

• To investigate the nature of the perinuclear compartment where overexpressed Cav1 accumulates.
• To determine if Cav1 contributes to protein aggregate formation and cellular stress responses.
• To elucidate the relationship between Cav1, aggresomes, and cellular protein quality control mechanisms.

Main Methods:

• Expression of Cav1-GFP constructs in various cell types.
• Immunofluorescence microscopy to visualize Cav1 localization and aggresome markers (vimentin).
• Analysis of protein turnover machinery (ubiquitin, VCP/p97, proteasomes) within Cav1-containing inclusions.
• Treatment with proteasome inhibitors to study endogenous Cav1 behavior.

Main Results:

• Overexpressed Cav1-GFP forms cytoplasmic inclusion bodies identified as aggresomes.
• These Cav1-containing aggresomes are vimentin-encased and microtubule-dependent.
• Aggresomes are enriched with ubiquitin, VCP/p97, and proteasomes, indicating involvement in protein turnover.
• Aggresome formation is cell-type dependent and occurs with various Cav1 constructs.
• Endogenous Cav1 also accumulates in aggresomes under proteasomal stress.

Conclusions:

• Cav1 can induce aggresome formation and is localized within these structures when misfolded.
• This finding offers new insights into cellular mechanisms for handling misfolded Cav1.
• Aggresome formation may contribute to cellular phenotypes associated with abnormal Cav1 expression or mutations.