Protogenin and ERdj3 participate in mouse vertebral patterning by regulating Hox gene expression

• Main Authors: Wei-Chih Kuo, 郭韋志
• Other Authors: Ming-Ji Fann
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/22582754933765278696

碩士 === 國立陽明大學 === 生命科學系暨基因體科學研究所 === 103 === Protogenin (Prtg) is an immunoglobulin superfamily gene that expresses from mouse embryonic day 7 to 10 (E7 to E10) and disappears after E10.5. This implies that Prtg may involve in regulation of early embryonic development. Prtg has been reported as a membrane receptor and an adhesion molecule which regulates neurogenesis, neural crest cell apoptosis and migration, and paraxial mesoderm cell ingression. ERdj3 has been found as a ligand of Prtg. In this study, I found that Prtg and ERdj3 knockout (Prtg-/- and ERdj3-/-) mice have defects on vertebral patterning. Skeletal staining of postnatal day 1 mice shows that Prtg-/- and ERdj3-/- mice exhibit anterior homeotic transformation in thoracic and lumbar vertebrae, a phenotypic characteristic similar to those of Hox6 to Hox10 mutants. According to this evidence, I hypothesize that Prtg and ERdj3 affect mouse vertebral patterning by regulating Hox genes. Results from in situ hybridization of E10.5 embryos show that expression of Hoxa7, Hoxa10, and Hoxd9 in somites is decreased in Prtg-/- embryos; expression of Hoxb6 and Hoxb9 is extended more posteriorly in Prtg-/- embryos; expression of Hoxc8 is increased in Prtg-/- embryos; expression of Hoxc9 is shifted posteriorly in Prtg-/- embryos; and expression of Hoxb2, Hoxb5, Hoxb8, Hoxc6, Hoxc10 and Hoxd10 has no difference between Prtg-/- and control embryos. These results reveal that Prtg has a novel function on vertebral patterning by specifically regulating expression of a subset of Hox genes. To study the molecular mechanisms of Hox gene regulation underlying Prtg and ERdj3, I used ES cell-derived mesodermal cells as an in vitro model. I demonstrated that a cultured protocol is able to differentiate ES cells into mesodermal lineage successfully by detecting their expression of Oct4 and Brachyury. Prtg, a subset of Hox genes, and Hox upstream genes are expressed in this ES-derived mesodermal cells. Taken together, this study found a novel function of Prtg and ERdj3 on vertebral patterning through Hox gene regulation, and generated a mesoderm cell model to examine Hox gene regulation by Prtg and ERdj3.