||School of Medicine, Institute for Biogenesis Research
||PhD (Kyoto University, Japan)
||(808) 692 1411
||(808) 692 1962
||651 Ilalo St., BSB 163A, Honolulu, HI 96813
Axis Specification and Germ Layer Formation in Mammalian Embryos.
Differentiation and Morphogenesis in Pluripotent Stem Cells.
Description of research:
How can a single cell, like the fertilized egg, transform into a complex architecture, like our body? With respect to this biggest question of Developmental Biology, my lab is currently conducting research projects under the following two main themes:
"Axis Specification and Germ Layer Formation in Mammalian Embryos"
Soon after implantation, the embryo of human or mouse is a single layer of epithelial tissue, called the epiblast. Later, one edge of the epiblast forms the structure called the primitive streak, from which cells migrate away to form new tissue layers. This event, i.e., the formation of the primary germ layers (ectoderm, mesoderm, and endoderm), is the first step towards the generation of complex body patterns. Furthermore, the primitive streak formation is the first morphological landmark of body axis specification, as it establishes the caudal end of the future body.
Activation of Wnt/beta-catenin signaling, an evolutionary conserved signal transduction machinery, is the key to the formation of the primitive streak in the epiblast. The specific questions that are addressed in my current projects are:
1) How Wnt/beta-catenin signaling is activated in a localized region of the epiblast?
2) What genes are turned on by Wnt/beta-catenin signaling in the primitive streak?
3) How can cells in the primitive streak transform from epithelial into migratory state?
"Differentiation and Morphogenesis in Pluripotent Stem Cells"
Embryonic stem (ES) cells and induced pluripotent stem (iPS) cells can be maintained and propagated in a culture dish as undifferentiated cell populations, which are very similar to early embryonic cells before germ layer formation. Because studies of mammalian embryos are often hindered by the unique reproductive mode of mammals (i.e., embryos normally develop in the uterus), pluripotent stem cells, like ES and iPS cells, can serve as great in vitro models, which can be experimentally manipulated more easily. Furthermore, these pluripotent stem cells offer tremendous promise for the future regenerative medicine, as they can be used to derive various types of functional tissues in vitro, and those stem cell-derived tissues may be used for tissue replacement therapy and drug screening.
The goal of my lab is to elucidate molecular and cellular mechanisms of differentiation (e.g., of mesoderm and endoderm tissues) and morphogenesis (e.g., of tissue elongation along the body axis) using mouse and human pluripotent stem cells.
Figure1: Confocal microscopy image of mouse E6.5 stage embryo, showing the distribution of pluripotency regulator OCT4 protein (green) and all the nuclei (red). The epiblast shows nuclear localization of OCT4 protein. Arrowhead indicates the site of the primitive streak formation.
Figure 2: in vitro axial elongation morphogenesis in aggregated P19 embryonal carcinoma cells. Scale bar = 1 mm.
- Alarcon, V.B., Marikawa, Y. (2004) Molecular study of mouse peri-implantation development using the in vitro culture of aggregated inner cell mass. Molecular Reproduction and Development 67, 83-90.
- Marikawa, Y., Fujita, T.C., Alarcon, V.B. (2004) An enhancer-trap lacZ transgene reveals a distinct expression pattern of the Kinesin family 26B in mouse embryos. Development Genes and Evolution 214, 64-71.
- Marikawa, Y., Fujita, T.C., Alarcon, V.B. (2005) Heterogeneous DNA methylation status of the regulatory element of the mouse Oct4 gene in adult somatic cell population. Cloning and Stem Cells 7, 8-16.
- Yamazaki, Y., Low, E.W., Marikawa, Y., Iwahashi, K., Bartolomei, M.S., McCarrey, J.R., Yanagimachi, R. (2005) Adult mice cloned from migrating primordial germ cells. Proceedings of the National Academy of Sciences of USA 102, 11361-11366.
- Alarcon, V.B., Marikawa, Y. (2005) Unbiased contribution of the first two blastomeres to mouse blastocyst development. Molecular Reproduction and Development 72, 354-361.
- Marikawa, Y. (2006) Wnt/beta-catenin signaling and body plan formation in mouse embryos. Seminars in Cell and Developmental Biology 17, 175-184.
- Yamazaki, Y., Fujita, T.C., Low, E.W., Alarcon, V.B., Yanagimachi, R., Marikawa, Y. (2006) Gradual DNA demethylation of the Oct4 promoter in cloned mouse embryos. Molecular Reproduction and Development 73, 180-188.
- Alarcon, V.B., Marikawa, Y. (2008) Spatial alignment of the mouse blastocyst axis across the first cleavage plane is caused by mechanical constraint rather than developmental bias among blastomeres. Molecular Reproduction and Development 75, 1143-1153.
- Tamashiro, D.A., Alarcon, V.B., Marikawa, Y. (2008) Ectopic expression of mouse Sry interferes with Wnt/beta-catenin signaling in mouse embryonal carcinoma cell lines. Biochimica et Biophysica Acta 1780, 1395-1402.
- Marikawa, Y., Tamashiro, D.A., Fujita, T.C., Alarcon, V.B. (2009) Aggregated P19 mouse embryonal carcinoma cells as a simple in vitro model to study the molecular regulations of mesoderm formation and axial elongation morphogenesis. Genesis 47, 93-106.
- Marikawa, Y., Alarcon, V.B. (2009) Establishment of trophectoderm and inner cell mass lineages in the mouse embryo. Molecular Reproduction and Development 76, 1019-1032.
- Marikawa, Y., Tamashiro, D.A., Fujita, T.C., Alarcon, V.B. (2011) Dual Roles of Oct4 in the Maintenance of Mouse P19 Embryonal Carcinoma Cells: As Negative Regulator of Wnt/beta-Catenin Signaling and Competence Provider for Brachyury Induction. Stem Cells and Development 20:621-633.
- Gelber K, Tamura AN, Alarcon VB, Marikawa Y. (2011) A potential use of embryonic stem cell medium for the in vitro culture of preimplantation embryos. Journal of Assisted Reproduction and Genetics 28:659-668.
- Tamashiro DA, Alarcon VB, Marikawa Y. (2012) Nkx1-2 is a transcriptional repressor and is essential for the activation of Brachyury in P19 mouse embryonal carcinoma cell. Differentiation. 83:282-292.
- Jaremko KL, Marikawa Y. (2012) Regulation of Developmental Competence and Commitment towards the Definitive Endoderm Lineage in Human Embryonic Stem Cells. Stem Cell Research. (in press)