Muscle Biology at Saint Louis University

Jonathan Fisher, Associate Professor 
joined SLU faculty in 2001

Skeletal muscle plays predominant roles in clearance of glucose from the blood and whole body energy metabolism.  The lab investigates aspects of muscle metabolism including regulation of glucose transport into muscle, alteration of growth-related and metabolic signaling within muscle cells, and control of mitochondrial function.  In particular, we are interested in regulation of glucose transport under basal conditions, under the influence of hormones such as insulin (which stimulates glucose transport into muscle), and under conditions of metabolic stress.

The signaling pathways and players that are central in our work include:
  • insulin/IGF-1 signaling
  • the AMP activated protein kinase (AMPK), a cellular fuel gauge that broadly controls energy metabolism, including potentiation of insulin action
  • Ataxia Telangiectasia Mutated (ATM), which has recently been found to play roles in metabolic actions
The goal of the main project in the lab is to elucidate factors that regulate glucose and dehydroascorbic acid (oxidized form of vitamin C) uptake by the GLUT1 glucose transporter.  The initial findings are here.  As we enter the next stage of the project, comparative physiologist  Dan Warren has helped us establish assays for reactive oxygen species, and biochemist Blythe Janowiak has graciously provided her expertise on enzymatic and enzyme activity assays.

We generally work with skeletal muscle or myotubes (cultured muscle cells that are differentiated into multinucleated, muscle-like cells).  Shown to the left is a confocal microscopic image of myotubes into which we have introduced green fluorescent protein (GFP).  We use GFP as a tool to demonstrate transfection or transduction efficiency or to examine subcellular localization of GFP-tagged proteins.  Susan Spencer, a neuroscientist in the department, took the photo shown above and the one to the right 
showing myoblasts (mono-nucleated cultured muscle cells) expressing GLUT1-GFP with a nuclear stain (red).  The GLUT1-GFP expression plasmid was generously provided by Jeffrey Rathmell (Duke University).

Here's our 2013 PhunWeek visit to Park Elementary School in the Ferguson-Florissant School District.  Left to right:  Jon, Stan (doctoral student), Gaytri (senior), Rikki (first year medical student), Liz (masters student), Emma (junior), and Obi (senior).

Stan Andrisse (shown handing out certificates and cash prizes with an assist from me) mentored Andrea Webber, Gatryi Patel, and Joe Chen in a project to determine factors that regulate GLUT1 localization and activity.  Andrea, Gaytri, and Joe received the second place award for undergraduate research from the Department of Biology in May, 2012.

Here's Stan in action at EB2012:

(click on photo to enlarge) Graduate students, undergraduates, high school students, and high school science teachers form a diverse research team.

The lab's work on regulation of glucose transport is relevant to diabetes mellitus, the hallmark of which is high blood glucose levels.

Graduate students Stan Andrisse (left) and Larry Spears (right) flank high school students David Rubenstein and Nell Briggs who joined the lab in summer, 2011, as part of the Students and Teachers as Research Scientists (STARS) program.  In fall, 2012, David will study biomedical engineering at George Washington University.  Nell is headed to the University of Pennsylvania.  Congratulations, Nell and David!

Below:  The GLUT1 Crew!

Larry at EB2012: