Palate morphogenesis: current understanding and future directions.
In the past, most scientists conducted their inquiries of nature via inductivism, the patient accumulation of "pieces of information" in the pious hope that the sum of the parts would clarify the whole. Increasingly, modern biology employs the tools of bioinformatics and systems biology in attempts to reveal the "big picture." Most successful laboratories engaged in the pursuit of the secrets of embryonic development, particularly those whose research focus is craniofacial development, pursue a middle road where research efforts embrace, rather than abandon, what some have called the "pedestrian" qualities of inductivism, while increasingly employing modern data mining technologies. The secondary palate has provided an excellent paradigm that has enabled examination of a wide variety of developmental processes. Examination of cellular signal transduction, as it directs embryogenesis, has proven exceptionally revealing with regard to clarification of the "facts" of palatal ontogeny-at least the facts as we currently understand them. Herein, we review the most basic fundamentals of orofacial embryology and discuss how functioning of TGFbeta, BMP, Shh, and Wnt signal transduction pathways contributes to palatal morphogenesis. Our current understanding of palate medial edge epithelial differentiation is also examined. We conclude with a discussion of how the rapidly expanding field of epigenetics, particularly regulation of gene expression by miRNAs and DNA methylation, is critical to control of cell and tissue differentiation, and how examination of these epigenetic processes has already begun to provide a better understanding of, and greater appreciation for, the complexities of palatal morphogenesis.
Greene
Robert M
RM
Department of Molecular, Cellular and Craniofacial Biology, University of Louisville, Birth Defects Center, ULSD, Louisville, Kentucky 40292, USA. dr.bob.greene@gmail.com
Pisano
M Michele
MM
D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D057225:Data Mining; D047108:Embryonic Development; D005260:Female; D053823:Hedgehog Proteins; D006801:Humans; D009024:Morphogenesis; D010159:Palate / Q000166:cytology / Q000196:embryology* / Q000378:metabolism; D011247:Pregnancy; D015398:Signal Transduction / Q000502:physiology; D016212:Transforming Growth Factor beta / Q000378:metabolism / Q000502:physiology
D019485:Bone Morphogenetic Proteins; D053823:Hedgehog Proteins; C509239:SHH protein, human; D016212:Transforming Growth Factor beta