Mechanisms of misfolded protein sequestration and degradation

/Abstract Misfolded proteins acquire toxic conformations that disrupt essential cellular processes, leading to cell death in diseases like cancer, Alzheimer’s, Parkinson’s, and Huntington’s diseases. Therefore, cells have developed different ways to manage misfolded proteins. This research will elucidate how cells sort misfolded proteins into distinct compartments that sequester and concentrate toxic, misfolded proteins for more efficient refolding or clearance. The quality control mechanisms that manage misfolded proteins wear down over time. This results in the buildup of protein aggregates that are a hallmark of proteinopathies. Identifying novel mechanisms for how cells sort misfolded proteins into quality control compartments will create numerous new therapeutic strategies to treat these devastating disorders. Previous work has shown that misfolded proteins are spatially sequestered into membrane-less compartments in the cell. However, we don’t know the mechanisms that control the formation, localization, and degradation of these compartments. This knowledge gap is even larger for aggregation-prone proteins such as those that cause disease. We will address the fundamental questions of why and how cells form inclusions, the role of inclusions in disease, and critically, how to promote degradation of these inclusions to prevent cell death in disease. These studies can also shed light on the apparent paradox of protein aggregates being both toxic and protective to cells. Our recent work elucidated a potential mechanism of degradation as compartments are recruited to the nucleus- vacuole junction (NVJ) to facilitate vacuolar clearance. ESCRT proteins, normally associated with protein trafficking, play an important role in this novel clearance mechanism. We are using a panel of misfolded proteins to probe the interactions required for sorting misfolded proteins into protein quality control compartments, transporting compartments to specific cellular sites, and determining clearance mechanisms for the compartments. We will accomplish this by using a combination of genetic deletions, live-cell time-lapse fluorescence microscopy, and a suite of biochemical techniques for determining changes in the aggregation state of proteins previously developed by the PI. The overall goal of our research is to uncover the basic cellular mechanisms that go awry in proteinopathies such as cancer and neurodegeneration. Project Number: 1R15GM163286-01 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of General Medical Sciences (NIGMS) | Principal Investigator: Emily Sontag | Institution: MARQUETTE UNIVERSITY, MILWAUKEE, WI | Award Amount: $569,258 | Activity Code: R15 | Study Section: Cell Structure and Function 1 Study Section[CSF1] View on NIH RePORTER: https://reporter.nih.gov/project-details/11292301