Andrew Hollenbach

Project:

Alveolar rhabdomyosarcoma (ARMS) is an aggressive childhood solid muscle tumor that has a poor prognosis with an event-free four-year survival rate of only 17%.  This fact emphasizes the necessity of the identification of novel molecular targets for rational drug design in the treatment of ARMS.  One if the most frequent soft tissue sarcomas in children, ARMS is characterized by the t(2;13)(q35;q14) chromosomal translocation which results in the fusion of two transcription factors that are important for muscle development, Pax3 and FKHR.  Despite the identification and characterization of the transcriptional properties of the oncogenic fusion protein Pax3-FKHR, little is known about how its transcriptional activity is regulated by post-translational events such as phosphorylation, how this regulation may differ from wild-type Pax3, or how this regulation may be important for the development of ARMS.  Inhibitors of phosphorylation are becoming key targets in the development of drugs for the treatment of cancer and may emerge as a key aspect in the development of treatments for ARMS.  Therefore, the overall objective of my project is to understand the manner in which phosphorylation regulates the transcriptional activity of Pax3 and how Pax3-FKHR may alter this regulation.  The information gained from the successful completion of this project will be essential for identifying molecular targets that will allow the rational drug design for the treatment of ARMS.

Relevant publications:

Dietz, K. N., Miller, P. J., and Hollenbach, A. D., (2008) “Identification of serine 205 as a site of phosphorylation on Pax3 in proliferating but not differentiating primary myoblasts.” Prot. Sci. [Epub ahead of print].

Sidhu, A., Miller, P. J., Johanson, K. E., and Hollenbach, A. D., (2008) “Novel flanking DNA sequences enhance FKHR (FOXO1a) DNA binding affinity but do not alter DNA bending.” Biochemistry June 7 [Epub ahead of print].

Bakkar, N., Wang, J., Ledner, K. J., Wang, H., Dahlman, J., Carathers, M., Acharyya, S., Rudnicki, M. A., Hollenbach, A. D., and Guttridge, D. C. (2008) “IKK/NF-kB Regulates Skeletal Myogenesis Via a Signaling Switch to Inhibit Differentiation and Promote Mitochondrial Biogenesis” J. Cell Biol. 180(4), 787 – 802.

Miller, P. J. and Hollenbach, A. D. (2007) “The oncogenic fusion protein Pax3-FKHR has a greater post-translational stability relative to Pax3 during early myogenesis.” Biochim. Biophys. Acta 1770(10), 1450-1458.

Pritchard, C., Grosveld, G. and Hollenbach, A.D. (2003) "Alternative splicing of Pax3 produces a transcriptionally inactive protein." Gene 305, 61-69.

Hollenbach, A.D., McPherson, C.J., Mientjes, D.J., Iyengar, R. and Grosveld, G. (2002) "Daxx and histone deacetylase ll associate with chromatin through an interaction with core histones and the chromatin-associated protein Dek" J.Cell Sci. 115, 3319-3330.

Hollenbach, A.D., McPherson, C.J., Lagutina, I. and Grosveld, G. (2002) The EF-hand calcium-binding protein calmyrin inhibits the DNA-binding and transcriptional activity of Pax3., Biochim. Biophys. Acta1574(3), 321-328.

Lam, P Y-P, Sublett, J.E., Hollenbach, A.D. and Roussel, M.F. (1999)The oncogenic potential of the Pax3-FKHR fusion protein requires the Pax3 homeodomain recognition helix but not the Pax3 paired-box DNA binding domain., Mol. Cell. Biol. 19, 594-601.

Hollenbach, A.D., Sublett, J.E., McPherson, C.J. and Grosveld, G. (1999) The Pax3-FKHR oncoprotein is unresponsive to the Pax3-associated repressor hDaxx., EMBO Journal 18, 3702-3711.

Contact info: aholle@lsuhsc.edu