In the broadest sense our lab is interested in the selective destruction of misfolded cellular proteins- a main line of defense that is harnessed by organisms to prevent the accumulation of these deleterious molecules. As a first step towards this goal, we are focused on discovering and studying proteostasis pathways in yeast, mammalian cells and multi-cellular eukaryotes, allowing us to synergistically capitalize on the investigative strengths that each has to offer. Here are some of the exciting research going on in the Neal lab!
ERAD and Retrotranslocation
The Endoplasmic Reticulum (ER) is one of the most intriguing organelles; playing critical roles in lipid synthesis as well as being major manufacturers of secretory and membrane proteins. Maintaining a healthy proteome is particularly challenging in the ER where high demand of protein synthesis generates constant misfolding stress. To off-set the catastrophic events that accompany accumulation of defective proteins, misfolded ER proteins are targeted for degradation via ER-associated degradation (ERAD). During ERAD, substrates destined for degradation are recognized by a membrane E3 ligase (i.e-Hrd1), tagged with a small molecule ubiquitin, delivered back into the cytoplasm by a dedicated export machinery, and degraded by the cytosolic proteasome. A unifying yet mysterious feature of all ERAD pathways is the requirement for removing misfolded substrates in to the cytosol; a process known as retrotranslocation. Hence, the major goal of the Neal lab is to understand this critical route of protein transport, and the family of proteins that mediate this branch of ERAD. Understanding this will hold great promise in both foundational and translational arenas of cell biology.
Rhomboids: a new mode in egress
We have recently discovered that a protein named Dfm1 – a member of a large but mysterious rhomboid superfamily is critical for retrotranslocating misfolded membrane substrates from the ER. This result is particularly exciting; answering a long-standing problem in foundational cell biology, and implicating the rhomboid family of proteins as key export factors in ERAD. The immediate goals we set out to address is to understand how Dfm1 and other rhomboids assist in the heroic thermodynamics of membrane protein extraction, to discover what cellular factors are involved in this action, and to discern the molecular underpinnings of failures in this process.
New stress pathway in membranes
We have also discovered that failure to remove misfolded membrane proteins from the ER cause a drastic cellular stress that appears to be distinct form the classic Unfolded Protein Response and thus there is of great interest in understanding the nature of this proteotoxic stress. Our goal is to unravel this novel stress pathway using a variety approaches including classical and reverse genetics and functional genomics to identify the pathways and participants altered upon initiation of this novel stress. This will reveal the molecular and biochemical precesses that result from this new strong stress at the ER membrane when retrotranslocation is not functioning properly.
Moving towards an integrated picture of protein quality control
We are interested in understanding protein quality control from an organismal perspective. Unraveling the mechanistic details associated with rhomboid-mediated export function will lay the groundworks for understanding the cellular and tissue specific roles of rhomboids in protein homeostasis. In addition, we are interested in using a chemical biology approach to identify small molecules that regulate rhomboid function. The generation of these compounds will provide a tidal wave of experiments that can quickly modulate ER export function and be used in other model systems for recapitulating disease phenotypes. This approach will transform the ERAD field by leaps and bounds in which clearance of disease-associated membrane protein will be precisely understood and provide molecular footholds for therapeutic intervention in ERAD-related diseases.