Degradation of Misfolded ER-retained Proteins
Proteins Proteins which are destined for the plasma membrane or for secretion are synthesized, folded to their proper form, and processed at the endoplasmic reticulum (ER). Under a variety of conditions, proteins become terminally misfolded in the ER and are targeted for degradation by quality control pathways. When this process is impaired, misfolded proteins accumulate in the endoplasmic reticulum (ER) and ultimately cause disease, such as diabetes or liver disease.
The most well characterized pathway for degradation of misfolded proteins in the ER is ER associated degradation (ERAD), which involves retrotranslocation of the protein to the cytosol and degradation by the proteasome. However, some misfolded proteins are poorly recognized by the ERAD system, necessitating their disposal by other pathway(s) that are not well characterized. To learn more about these alternate ER-associated degradation pathways, we have created a fluorescent protein (FP)-tagged misfolding protein that is localized in the ER at steady state.
We plan to use both biochemical and advanced microscopy techniques to examine the factors involved in targeting ER-retained misfolded protein for degradation, as well as to look at how the different degradation pathways interact. The findings from this study may provide novel insights into the regulation of degradation pathways utilized by disease-related, ER-retained proteins.
Figure: Shown here is an NRK cell co-expressing a YFP-tagged misfolding variant of the prion protein (yellow) with KDEL-CFP, an ER-marker (cyan). The YFP-PrPmisf is localized to the ER in steady-state conditions. We will examine the degradation pathways of this misfolded ER-retained PrP. Click the image for a larger view.
For more information, contact Prasanna Satpute-Krishnan.