CBS Faculty Office: 4256

• Assc. in Chemistry, Lake Superior State University, 1996
• B.S. in Biology, Lake Superior State University, 1996
• M.A. in Kinesiology, University of Texas at Austin, 1999
• Ph.D. in Kinesiology, University of Illinois-Chicago, 2004

My overall research interest is to determine how skeletal muscles sense mechanical information and convert this stimulus into the molecular events that regulate changes in muscle mass. This interest has led me to study a protein kinase called the mammalian target of rapamycin (mTOR). Signaling by mTOR is necessary for mechanically-induced growth of skeletal muscle, and I have recently determined that mechanical stimuli activate mTOR signaling through a unique mechanism involving phospholipase D and the lipid second messenger phosphatidic acid (PLD→PA→mTOR). Based on this observation, my lab has focused on three projects which are all aimed at further defining how mechanical stimuli activate the PLD→PA→mTOR pathway and skeletal muscle growth.  

•  Live Cell Imaging of Mechanically-Induced Signaling Events
• Defining the Mechanically-Induced PLD→PA→mTOR Signaling Pathway
• Identification of  Molecules that Regulate Skeletal Muscle Growth / Atrophy

To learn more about these projects, please visit the lab website:

HORNBERGER LAB

Assistant Professor

• Principles of Vertebrate Physiology

•   Comparative Biomedical Sciences Graduate Program
•    Program in Cellular and Molecular Biology

Hornberger TA, Sukhija KB, Wang XR and Chien S. mTOR is the rapamycin-sensitive kinase that confers mechanically-induced phosphorylation of the hydrophobic motif site Thr(389) in p70(S6k). FEBS Letters 2007 Oct 2; 581(24): 4562-6. [Abstract]

Hornberger TA, Sukhija KB and Chien S. Regulation of mTOR by Mechanically Induced Signaling Events in Skeletal Muscle. Cell Cycle 2006  Jul 1; 5(13): 1391-1396.[Abstract]  

Hornberger TA, Chu WK, Mak YW, Hsiung JW, Haung S, and Chien S.  The Role of Phospholipase D and Phosphatidic Acid in the Mechanical Activation of mTOR Signaling in Skeletal Muscle. Proc Natl Acad. Sci USA 2006  Mar 21;103(12): 4741-6. [Abstract]  

Hornberger TA, Chien S.  Mechanical Stimuli and Nutrients Regulate Rapamycin-Sensitive Signaling Through Distinct  Mechanisms in Skeletal Muscle.  J. Cell. Biochem. 2006 Apr; 97(6): 1207-1216. [Abstract]

Hornberger TA, R.D. Mateja, J.L. Andrews and K.A. Esser. Aging does not alter the mechanosensitivity of the p38, p70S6k and JNK2 signaling pathways in skeletal muscle. J Appl Physiol. 2005 Apr; 98(4) 1562-1566. [Abstract]   

Hornberger TA, Armstrong D, Koh, T. Burkholder T, Esser KA.  Intracellular Signaling Specificity in Response to Uniaxial vs. Multiaxial Stretch: Implications for Mechanotransduction. Am J Physiol Cell Physiol. 2005 Jan; 288(1): C185-C194. [Abstract]   

Hornberger TA, R. Stuppard, K.E. Conley, M.J. Fedele, M.L. Fiorotto and K.A. Esser. Mechanical Stimuli Regulate Rapamycin-Sensitive Signaling by a Phosphoinositide 3-kinase, Protein Kinase B and Growth Factor Independent Mechanism. Biochem J. 2004 Jun 380(Pt 3): 795-804. [Abstract]