Focus, Philosophy and the Training Environment

Our laboratory is focused on studying the actin cytoskeleton, the critically important organizing structure found within the cytoplasm of our cells. The filamentous networks formed from the actin protein are so central to cell function that virtually no process within our cells, from growth and cell division, development, signal transduction, adaptation, to gene expression and more can properly operate without an actin cytoskeleton. It is therefore not surprising that many aspects of human disease including genesis and treatment are intimately tied to this important structure. Note that the figure at left (complements of Dr. Andreas Bremer) is a reconstruction of a single actin filament. Our interests lie in how regulation of the actin cytoskeleton contributes to diverse human disease states such as the rampant cell division and metastasis that occurs in cancerous tissues, how changes in actin organization contribute to immune cell development and function, how normal tissues adapt and survive the extreme stress conditions that accompany many treatment regimens, and the role of actin damage in the loss of red blood cell plasticity that leads to sickle cell crisis. In fact, actin is so important that our studies are likely to have influence in areas we cannot yet contemplate.

Our experimental approach is to focus on understanding how actin binding proteins regulate the dynamics and organization of the actin networks within our cells. Part of this effort is to identify new actin binding proteins and ask how they may influence actin dynamics in ways that may relate to medically relevant problems. This approach is always leading to the introduction of new research projects in the lab that typically become the focus for a single graduate student or post-doctoral fellow, the resulting sense of ownership over a problem creates an ideal training environment for young scientists. This training experience is further enriched by our utilization of powerful experimental systems that allow us to take a multi-pronged attack to any problem of interest, employing state-of-the-art cell biological, biochemical, molecular biological, structural, microscopy and genetic approaches. This adds great dimension to the training environment, allowing students to learn how to do science from several perspectives with well-controlled experiments and with a speed that allows for many experiments to be designed and executed in a relatively short period of time.

We are currently focusing on three specific biological problems. The first two relate to how cells adapt to stress: one to oxidative stress and the second to osmotic stress. The third problem relates to how actin networks are remodeled by a powerful actin filament breaking (severing) machine. The research goals are to understand at the cellular, molecular and, in fact, the atomic level the mechanisms of how these proteins are affecting the actin cytoskeleton. In addition, we have recently entered the arena of genomics to try and identify all genes that impact the function of the actin cytoskeleton and to subdivide this large network of genes into functional categories. Currently both our gene specific studies and our genomics work are funded with two separate NIH grants. However, the greater goal is to use the lab to create an optimal training environment for young scientists that teaches them how to ask a question and answer that question in a way that leads to the publication of meaningful papers in top tier journals. The purpose is not to merely train technicians but to train intellectuals that can start with a hypothesis and develop a meaningful contribution to our understanding of biology.

Other Goodies:

If the preceeding information has perked your interest, there is much more information to be found on the links below. For example, Dr. Amberg's initial interest in actin was focused on developing genetic methods to study how the surface of this relatively simple protein was interacting with so many accessory proteins. In his post-doctoral work with Dr. David Botstein, he adapted the two-hybrid protein interaction reporter system to study this problem. He identified several ligands that will interact with actin in the two-hybrid system and tested the ability of 35 clustered-charged-to-alanine scanning mutants of actin to interact with these ligands. This is what we call defining "differential interactions in the two-hybrid system".

Those actin mutations that disrupt a given interaction help define how the proteins are contacting each other. This can be most readily appreciated by examining our pictures showing the modeling of this data on the structure of actin. Perhaps the best example is the data for the Actin-Aip1 interaction, mutations that disrupt this interaction are shown in red.

There are some other handy items you can get to from this page including a list of everything we know about the genetic and physical interactions between proteins involved in yeast actin-cytoskeleton function. Note that this diagram is now out of date but is still very useful to show how beneficial genetic analysis can be. We have also been involved in imaging the actin cytoskeleton in three-dimensions and the images we have obtained can be seen below. Note that we have always made these images available even prior to publication but would certainly appreciate an acknowledgement when they are used in seminars and talks. Finally, additional and new information on Aip1p, Aip3p and Ssk2p will be made available and accessible through the links below.

High Res., Three-Dimensional Images of The Yeast Actin-Cytoskeleton	The Actinome Project
More on AIP1	More on SSK2	More on Aip3/Bud6