Title: A new cell model to investigate the contribution of FIT2 on ApoB biogenesis and VLDL secretion
Abstract:
Cholesterol build-up in arterial walls leads to plaque formation, causing atherosclerosis, a condition that results in coronary artery disease, claiming 610,000 lives annually and ranking as the third leading cause of mortality worldwide. Although the mechanism of cholesterol uptake by tissues has been elucidated, certain aspects of how lipids are loaded onto a hepatic scaffold protein, apolipoprotein B (ApoB), and secreted as very-low density lipoprotein (VLDL) into circulation to transport cholesterol to tissues, is less clear.
Lipid loading onto ApoB occurs in two steps: the first is mediated by microsomal triglyceride transport protein, followed by a second step involving the less-defined, endoplasmic reticulum (ER) resident fat storage-inducing transmembrane protein 2 (FIT2). It is known that FIT2 aids in the formation of cytosolic lipid droplets. I hypothesize that given its ER localization, FIT2 functions bi-directionally, creating lipid droplets in the ER lumen that are added to partially lipidated ApoB, promoting VLDL secretion.
To test this hypothesis, we have developed a ‘humanized’ McArdle cell model lacking the RNA editing enzyme APOBEC1, ensuring expression of only the ApoB100 isoform of the protein, as observed in human hepatocytes. After characterizing this model, I will investigate: a) changes in VLDL secretion in the absence of FIT2; b) the impact of lipid accumulation in the ER membrane on the ability of ER-associated degradation (ERAD) substrates to retrotranslocate into the cytosol; and c) the induction of stress pathways like the unfolded protein response and ER phagy due to lipid accumulation
Title: The Appelmans protocol: Using methods from the past to train the phages of the future
Abstract:
Viruses that infect bacteria, known as bacteriophages, are being re-examined as potential therapeutics to combat bacterial infections. A major constraint to the widespread use of phages in medicine is the limited host-range phages have for their bacterial host. Specificities of individual phages to their hosts are often as narrow as the strain level of bacteria. Indeed, while the Hatfull lab has been able to treat over 20 patients suffering from non-tuberculosis mycobacterial (NTM) infections, many patient-derived NTM isolates are not susceptible to any phages in our collection and thus cannot be considered as candidates for phage therapy. This is especially true for Mycobacterium abscessus clinical isolates which have two distinct colony morphologies: smooth and rough. While approximately 80% of rough M. abscessus isolates are susceptible to at least one phage in our collection, the same can only be said of around 40% of smooth strain isolates. Furthermore, almost no smooth strains are effectively killed by the few phages that are able to infect those strains. The problem of identifying phages that can infect and kill smooth strain M. abscessus has been a difficult one to overcome. A solution to this problem may come from a mostly forgotten, century old, method to train phages to obtain an expand host range: the Appelmans protocol. This method can be used to leverage experimental evolution of multiple phages against multiple bacterial hosts to increase the host range of one or more of those phages. The successful implementation of this method has resulted in the expansion in the host range of at least one phage (Muddy_HRMAR8) which is now able to infect and kill several smooth strain M. abscessus isolates.
Brodsky and Hatfull Lab
Friday, October 11th, 2024
12:00PM
Langley A219B