Welcome! You have reached the homepage for the laboratory of Dr. Bryan Heit. Our lab is part of the Department of Microbiology and Immunology at Western University, and we are members of the Center for Human Immunology, the lead centre for the CIHR Human Immunology Network.
Our interests surround the function of phagocytes – white blood cells which ingest (phagocytose) pathogens, particles, and dead cells. We focus on the cellular and molecular processes which control the function of these cells during the maintenance of homeostasis, infection and chronic inflammatory disease. Central to most of our studies is the study of efferoctyosis – the phagocytic removal of apoptotic (dying) cells, and how failures in this process lead to inflammation, autoimmunity and infection.
Phagocytes are a class of white blood cells which have the capacity to engulf large particles such as bacterial and fungal pathogens, and subsequently destroy the engulfed material. The term phagocyte literally translates to “cell that eats”, which is an apt description of the primary function of these cells in our bodies. While there are many types of phagocytes, the Heit lab focuses primarily on macrophages, which play key roles in both maintaining our bodies and in fighting infections.
The Heit lab is excited to announce the discovery of membrane cages, a previously undescribed membrane structure.
This discovery has been published in the journal Scientific Reports. Membrane cages act to transiently block the diffusion of membrane proteins, thus structuring proteins in cellular membranes over short periods of time. This discovery was made, with our collaborator Dr John de Bruyn in the Department of Physics, through a combination of super resolution microscopy and classical cell biology techniques. We used high-speed super resolution microscopy to track the diffusion of CD93 – a macrophage receptor – and discovered that CD93 occasionally became trapped into membrane sub-regions that did not correlate to other known cellular structures. Through a range of experiments we were able to demonstrate that these “cages” were short lived (milliseconds to seconds), were independent of a previously described membrane structures, and that cages require cholesterol for their stability and strength.
Much remains to be discovered about the purpose and composition of this new cellular structure, but we expect cages to play an important role in structuring membrane proteins into functional units. Of particular interest to our lab is the negative impact of excess cholesterol on cages, an observation which suggests that some of the cellular deficiencies observed during diseases such as atherosclerosis (heart disease) may be a product of altered cage structure or function.
Dr. Gregor Reid, professor in the Department of Microbiology and Immunology at the University of Western Ontario, was just named a Fellow of the Royal Society of Canada! Dr. Reid is a pioneer in the study of probiotic organisms and the microbiome, and is leads our departments priobiotic research group. More information on his research and publications can be found at the webpage for the Microbiome and Probiotics Research Group.
This week the newest graduate students began working in the Department of Microbiology and Immunology. The Heit lab would like to welcome all of these new students to our department, including to Kyle, the newest member of the Heit lab!
Yesterday Dr. Roger Y. Tsein of the University of Californian, San Diego, passed away. Dr. Tsein’s work has had a profound impact on the work performed in the Heit lab. Indeed, over half of the experiments we conduct would not have been possible without his discovery and development of fluorescent proteins such as GFP.
In our lab these fluorescent proteins are used daily – we attach them to proteins of interest to track their location in cells, use variants of them to report biochemical activity and detect inter-protein interactions, and even use them to track cells within living organisms. And we are not alone – you would be hard-pressed to find a cell biology lab that doesn’t use fluorescent proteins in some aspect of their work. Examples of fluorescent images from the Heit lab can be seen in the image slider at the top of the page.
Dr. Ysein was awarded the 2008 Noble Prize in Chemistry for his work on fluorescent proteins, and continued to make significant contributions through to the end of his career.
We have lost a giant among us, and he will be sorely missed.