Regulation of the Transcription Factor CREB in Skeletal Muscle after Exercise

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David M Thomson, Physiology and Developmental Biology

Evaluation of mentoring environment

My laboratory is running quite smoothly now. The students in the laboratory are proficient in performing experiments, obtaining data and interpreting it. My first undergraduate students have recently graduated, and I now have a nice array of experienced and newer inexperienced students, so the work is moving forward steadily, both in terms of productivity and of student training. I enjoy seeing students come into the lab with essentially no knowledge of laboratory techniques and the particular physiological topics that we study, and within a couple of months gaining enough knowledge to contribute to an intellectual discussion of the principles we study.

Our lab meetings are also going very well. All students in the lab present either data from their experiments or journal club articles where they review recently published data within our field of research. They are doing very well with this. It has been interesting to see the improvement in the quality of these presentations from semester to semester as the students increase their knowledge and understanding.

In September I was able to take three undergraduate students (Chris Flint, Kat Yokoyama and Shawn Platt) to the Integrative Physiology of Exercise conference in Miami , with MEG funding. Chris and Kat presented data obtained in part by this MEG grant. They all prepared very nice poster presentations. I was proud of the job they did. The project Chris is working on should be completed by the end of the year and will be submitted for publication. Kat’s project will probably be wrapped up next year. In all, I think that the current mentoring model is working well in giving students a high-quality and productive laboratory experience.

I’ve recently made some adjustments to my writing and teaching preparation schedules that allows me more time to get into the lab and work directly with the students at the bench than I previously had. I’m finding that this vastly improves lab productivity and student learning.

Participating students

The students currently participating in the work funded by this grant are:

  • Katherine Yokoyama
  • Ben Barton
  • Cameron Lamb
  • Megan Nuttall
  • Chris Flint
  • Zac Olesky
  • Derrick Hall

Evaluation of academic objectives and project findings

The purpose of the MEG that was funded last year was to characterize the regulation of CREB transcriptional activity after an hour-long exercise bout. We had a delay in getting this project started due to other pressing projects. However, preliminary data collection has been underway now for approximately 2 months. Ryan DiGiovanni, who has been in the lab for a little over a year now, has been leading the project and has helped supervise Catherine, Katherine, Ben, and Cameron in the experiments performed so far.

The primary objectives accomplished or nearly accomplished on the project to date are (stuents involved in parenthesis):

Objectives reached last year

  • We have fine-tuned the electrical stimulation protocol that we are using to study CREB activation so that it is appropriate for the measures we are looking to obtain. We have electrically stimulated two rats at 4 time-points and collected pilot tissues to ensure that our measures will work properly (Ryan).
  • We have worked out western blotting methods for CREB and TORC detection, and have identified TORC2 in skeletal muscle (Ryan, Catherine, Katherine, Ben, Cameron).
  • We are in the process of fine-tuning the methods for co-immunoprecipitation of CREB and TORC (Ryan).
  • Quantitative real-time PCR optimization is currently being done for mitochondrial proteins. (Catherine and Katherine)
  • We have successfully isolated nuclear and cytosolic fractions from skeletal muscle and verified the quality of the fractionation by western blotting for nuclear and cytosolic proteins. This is an important step in being able to perform the proposed nuclear run-on assays (Cameron).

This year’s research objectives reached

  • We determined that TORC2 and CREB localization do not consistently change during the time frame we looked at (Ryan, Chris, Kat).
  • mRNA for the The CREB target SIK1 is elevated in LKB1 KO mice vs. controls.
  • We’ve turned our attention to other potentially interesting transcription factors and events during contraction- Kat has shown that phosphorylation of the progesterone receptor increases with exercise in and LKB1-dependent manner.
  • Chris is showing that satellite cell activation in LKB1-deficient mice may be somewhat deficient perhaps through the MEF2 transcription factor.

We’ll finish out this project this by further collecting data on the progesterone and finishing the MEF2/satellite cell activation project. I expect both projects will lead to publications.