Amieh Joi Brooks
Project Year
Amieh with lab equipment.

Peroxisomes are small, membrane-bound organelles in eukaryotic organisms responsible for key metabolic processes, including fatty acid breakdown. Cells maintain metabolic homeostasis by dynamically adjusting their peroxisome numbers through peroxisome biogenesis and pexophagy, the peroxisome-specific form of autophagy, which removes damaged or stressed peroxisomes before they cause cell toxicity. Improper regulation of peroxisomes can result in Peroxisome Biogenesis Disorders (PBDs), a class of developmental disorders caused by mutations in biogenesis-related Pex proteins. The peroxisome stress caused by acute rather than chronic peroxisome dysfunction is similar to the effects of aging. To induce peroxisomal stress, we focused on the downstream effects of import stress– the interruption of selective transport into the peroxisome– caused by the inducible cleavage of the N-terminus of Pex5, the cytosolic receptor protein responsible for peroxisome protein import. We generated yeast strains expressing a galactose-inducible TEV protease (a site-specific protein-cleaving enzyme) alongside Pex11-GFP, a peroxisomal membrane protein tagged with Green Fluorescent Protein that serves as a reporter for organelle degradation, and monitored peroxisomal degradation, using immunoblotting to probe for the accumulation of free GFP compared to the full length Pex11-GFP. Here we show that our TEV system induces Pex5 cleavage as designed; and that we can readout the Pex11-GFP reporter. However, there is no observable difference in free GFP signal between the positive and negative controls under galactose conditions. Further protocol optimization is required in order to read out the effects cleaving Pex5 has on pexophagy. Future directions will include adjusting sample saturation to eliminate nutrient starvation as a confounding variable. Being able to induce peroxisome stress in vivo and monitoring pexophagy will serve as a tool for identifying regulatory signals that maintain peroxisomal homeostasis.

 

Major
Biology
Faculty Sponsor(s):
Brooke Gardner
Departments:
Cellular, Molecular and Developmental Biology
Mentor(s):
Milagros Esmerode