Christi Kern, PhD, Assistant Professor
The Role of Prrx Regulation of Extracellular Matrix Genes in Craniofacial Development
We are interested in the morphogenetic processes governing craniofacial development. Cleft palate is one of the most common craniofacial malformations in humans, impacting approximately 1 in 1000 live births. However the molecular mechanisms governing secondary palate formation prior to fusion are not well understood. Using mouse models deficient in the homeobox transcription factors Prrx1 and Prrx2 or goal is to understand the genetic circuitry involved in development of the secondary palate and determine altered genetic programs that result in cleft palate formation.
We have recently discovered that Prrx1 homeobox transcription factor is expressed in the secondary palatal shelves throughout fetal development and mice deficient in Prrx1 display a cleft palate defect resulting from a lack of vertical palate elevation in 100% of homozygous offspring. This defect is more severe in Prrx1/Prrx2 double deficient embryos. Three-dimensional (3D) reconstructions of the palatal shelf regions in both wild type (WT) and Prrx double knockout mice revealed obvious malformations by E14.5; by E15.5 3D reconstructions revealed that the secondary palate had not elevated and that the tongue was also severely malformed and hypoplastic compared to WT littermates. Since the Prrx genes encode paired related homeobox-containing DNA binding transcription factors, our recent focus has involved the identification of direct downstream transcriptional targets. We have identified several extracellular matrix genes that may be direct targets of the Prrx1 and Prrx2 paired-type related homeodomain proteins and are the focus of our ongoing research. Recently, and the focus of this study, using a combination of in vitro, ex vivo and in vivo experiments we have demonstrated that Prrx1 and Prrx2 regulate transcription of the proteoglycan versican. Due to the fact that versican is a direct target of Prrx1 and that changes in hydration of the ECM have been hypothesized to play a role in palatal elevation we examined the expression of versican in Prrx1 deficient mice at E13.5 and E14.5 time points prior to the Prrx1 cleft palate phenotype. At E13.5 and E14.5 there is a significant increase in versican localization throughout the developing palatal shelves. Our ongoing studies will seek to further characterize the dysmorphogenesis of the secondary palate in the Prrx deficient embryos and the corresponding levels of versican. We will examine the changes in cellular behavior of palatal mesenchyme in the Prrx1 deficient embryos compared to WT littermates. Finally we will determine the pathways altered in the Prrx deficient palatal shelves to begin to elucidate the role of Prrx1 in the genetic circuitry of secondary palate development. Recently, a SNP study identified PRRX1 as a candidate gene in cleft palate birth defects. Therefore, our Prrx mutant mice are a relevant and novel mouse model that may facilitate uncovering the genetic circuitry involved in normal secondary palate and cleft formation.
- R. Mukherjee, W.T. Rivers, J.M. Ruddy, R.G. Matthews, C.N. Koval, R.A. Plylar, E.I. Chang, R.K. Patal, C.B. Kern, R.E. Stroud, and F.G. Spinale. Long-Term Localized High-Frequency Electric Stimulation Within the Myocardial Infarct; Effects on Matrix Metalloproteinases and Regional Remodeling, Circulation 2010 In Press.
- C.B. Kern, A. Wessels, J. McGarity, L. Dixon, E. Alston, W.S. Argraves, D. Geeting, C.M. Nelson, D.R. Menick and S.S. Apte. Reduced versican cleavage due to Adamts9 haploinsufficiency is associated with cardiac and aortic anomalies, Matrix Biology, 2010 May; 29(4): 304-16.
- S.K. Mani, E.A. Egan, B.K. Addy, M. Grimm, H. Kasiganesan, T. Thiyagarajan, L. Renaud, J.H. Brown, C.B. Kern and D. R. Menick. Beta-Adrenergic receptor stimulated Ncx1 upregulation is mediated via CaMKII/AP-1 signaling pathway in adult cardiomyocytes, J Mol Cell Cardiol, 2009 In Press.
- R. H. Anderson, R.P. Thompson and C. B. Kern. Development of aortic valves with 2 and 3 leaflets, Journal of the American College of Cardiology, 2009, Dec 8;54(24):2319-20.
- S. Chandrasekaran,# R. E. Peterson,# S. K. Mani, L. Renaud, A. L. Buchholz, B. Addy, L. Xu, T. Thiyagarajan, C. B. Kern and Donald R. Menick. Histone Deacetylases Facilitate Ncx1 Upregulation in Adult Cardiocytes 2009 Faseb Journal, Nov;23(11):3851-64
- B. Snarr, C.B. Kern, and A. Wessels. Origin and Fate of Cardiac Mesenchyme, Developmental Dynamics 2008 Oct; 237 Jul (10): 2804-19.
- M. A. Cooley, C.B. Kern, V.M. Fresco, A. Wessels, R.P. Thompson, T. C. McQuinn, W. O. Twal, C. H. Mjaatvedt, C. J. Drake and W. S. Argraves. Fibulin-1 is required for morphogenesis of neural crest-derived structures, Developmental Biology 2008 15;319 (2):336-45.
- E.W Wirrig, B.S. Snarr, A. L. Phelps, J. L. Barth, V. M. Fresco C.B. Kern, C.H. Mjaatvedt, B. P. Toole, S. Hoffman, T.C. Trusk, W.S. Argraves, and A. Wessels. Cartilage Link Protein 1 (Crtl1), an extracellular matrix component playing an important role in heart developmental Developmental Biology 2007 Oct. 15;310(2):291-303.
- C.B. Kern, R.A. Norris, R.P. Thompson, W.S. Argraves, S.E. Fairey, L. Reyes, S. Hoffman, R.R. Markwald and C.H. Mjaatvedt Versican proteolysis mediates myocardial regression during outflow tract development. Developmental Dynamics 2007 Jan16;236(3):671-683.
- R.A. Norris, V. Mironov, B. Damon, V. Kasyanov, A. Ramamurthi, R. Moreno, T. Trusk, J. Potts, R. Goodwin, J. Davis, S. Hoffman, X. Wen, Y. Sugi, C.B. Kern, G. Forgacs, C. H. Mjaatvedt, D. Turner, and R. R. Markwald. Periostin binding to collagen Type IIS necessary for proper regulation of collagen fibrillogenesis and maintaining the biomechanical properties of connective tissues. J Cellular Biochemistry 2007 Jun 1;101(3):695-711.
- C.B. Kern, W.O. Twal, C.H. Mjaatvedt, S.E. Fairey, B.P. Toole, M.L. Iruela-Arispe and W.S. Argraves. Proteolytic Cleavage of Versican During Cardiac Cushion Morphogenesis. Developmental Dynamics 2006 Aug;235(8):2238-47.
- C.H. Mjaatvedt, C.B. Kern, R.A. Norris, S. Fairey, and C.L. Cave. The Normal Distribution of Melanocytes in the Mouse Heart. Anatomical Record. Part A, Discoveries in Molecular, Cellular, & Evolutionary Biology 2005 285(A): 748-757.
- R.A. Norris, C.B. Kern, A. Wessels, E.E. Wirrig, R.R. Markwald and C.H. Mjaatvedt. Detection of the Chicken IG-H3 Gene During Cardiac Development and its Complementary, Non-overlapping Pattern with Periostin. Anatomy and Embryology Anat Embryol (Berl). 2005 Aug; 210(1):13-23.
- C.B. Kern, S. Hoffman, R. Moreno, B.J. Damon, R.A. Norris, E.L. Krug, R.R. Markwarld and C.H. Mjaatvedt. Immunolocalization of Chick Periostin Protein in the Developing Heart. Anatomical Record. Part A, Discoveries in Molecular, Cellular, & Evolutionary Biology. 2005 284A: 415-423.