Rodney M. Dale
Ph.D. 2007, University of Chicago
Developmental Biology & Bioinformatics
Lab webpage: Dalelab.weebly.com
Multiple studies have now demonstrated that it is not the number of genes that are critical for the structural differences observed between animals, but how the many conserved orthologous genes are regulated. Throughout evolution, natural selection has found ways to keep or introduce non-coding DNA sequence, known as regulatory elements, into the genome that transcription factor proteins can bind to and control the time and place other genes are expressed. This has resulted in the large structural variation observed between organisms while still using similar homologous genes.
My research interests lies in understanding the genetic regulation of critical structural genes and how we can use identified regulatory elements to drive gene expression at desired times and places. My experimental paradigm uses the zebrafish, Danio rerio, to understand the genetic regulation of cartilage and bone formation of the vertebrate skull and notochord. As most vertebrates share a common developmental path using homologous genes and genetic networks to produce a mature animal, the zebrafish has proven to be an excellent tool to study aspects of normal and impaired vertebrate maturation. This is due to the zebrafish being amenable to the powerful and innovative combination of genetic, embryological, molecular and high-throughput techniques.
1. Identification of the tissue specific transcription factor binding sites critical for the col2a1a R2 regulatory element expression.
In Dale and Topczewski 2011, we identified a small novel regulatory sequence (R2) upstream of the col2a1a gene, one of two zebrafish homologues of the mammalian col2a1 gene. The R2 fragment is able to drive gene expression that recapitulates much of the endogenous expression of col2a1a in the developing cartilage, notochord, and ear. The goal of this project will be to genetically dissect the R2 sequence to identify the critical transcription factor binding sites that allow it to drive expression in these three tissue types.
2. Elucidate the mechanism of perichondrial expression of col2a1b during craniofacial development.
Unlike terrestrial vertebrates, the zebrafish, along with other teleost and jawless fish, have two COL2A1 homologues, col2a1a and col2a1b, suggesting that terrestrial vertebrates lost one of these genes after their evolution from fish. Interestingly, the genomic neighborhood around zebrafish col2a1b has been linked to the human chromosomal region containing COL2A1, and their respective proteins are more closely related than to col2a1a, but based on our previous work the expression pattern of col2a1b is not seen in chondrocytes but in the perichondrium, whereas col2a1a is expressed in both the perichondrium and chondrocytes.
Little is known about the function or the genetic regulation zebrafish col2a1b, but its expression in the perichondrium around the cartilage elements of the zebrafish cranium makes it an excellent target for promoter analysis for regulatory elements to drive gene expression in the forming perichondrium. While the perichondrium plays a critical part in cartilage development, few have looked at its role specifically. The col2a1b perichondrium regulatory element will allow us to study the morphogenetic changes in the perichondrium during the maturation of the vertebrate animal, which up to this point has not been well characterized.
3. The role of notochord sheath cells in intervertebral disc formation.
Beside congenital defects wear and tear of skeletal elements over a lifetime has become a major healthcare issue, as seen in intervertebral disc (IVD) degeneration and herniation, which are becoming more common in our aging industrialized societies. In mouse, it has been postulated that the notochord gives rise to a subpopulation of IVD cells, but how these cells migrate and form this critical structure has yet to be understood. By understanding the process of IVD formation researchers may discover novel therapies for IVD degeneration.
The larval zebrafish notochord is composed of two cell types, vacuolated cells (VC) and notochord sheath cells (NSC). In Dale and Topczewski, 2011, we used our Tg(1.7c2a1a:GFP) reporter fish line to identified the process by which the NSC retract from the forming embryonic notochord and surround the swelling VCs. The vertebrae of the zebrafish spine, called centra, form around the notochord in regular intervals, which are separated by IVD. In our R2 col2a1a derived transgenic fish the NSCs surrounding the notochord where centra are forming loose reporter activity, while those in the region that will give rise to the IVDs maintain reporter activity through adulthood. We are currently setting out to characterize the cellular changes and migration of NSCs plays in zebrafish IVD development using our Tg(R2c2a1a:GFP) zebrafish transgenic.
2012 Topczewski, J, Dale, RM, and Sisson, BE. PCP signaling in Craniofacial Development,
Organogenesis, Vol. 7, (4):255-59
2011 Dale, RM, and Topczewski, J, Identification of an evolutionarily conserved regulatory
element of the zebrafish col2a1a gene, Developmental Biology, Vol. 357, (2):518-531.
2010 Demonbreun, AR, Lapidos, KA, Heretis, K, Levin, S, Pytel, P, Dale, RM, Svensson, EC,
McNally, EM. Myoferlin regulation by NFAT in muscle injury, regeneration, and repair.
Journal of Cell Science, Vol. 123 (14):2413-22.
2009 Dale, RM, Sisson, BE, and Topczewski, J, The emerging role of Wnt/PCP signaling in
organ formation, Zebrafish, Vol. 6 (1):9-14
2007 Dale, RM, Remo, BF, and Svensson, EC. An alternative transcript of the FOG-2 gene
encodes a FOG-2 isoform lacking the FOG repression motif, Biochemical and
Biophysical Research Communications, Vol. 357 (3): 683-687.
2005 Svensson, EC, Wilk, J, Dale, RM, and Modrell, M. “The role of the transcriptional co-
repressor FOG-2 in cardiac development” in, Cardiovascular Development and
Congenital Malformations Artman, M., Benson, D.W., Srivastava, D., and Nakazawa,
M. (eds), p125-127.