333
Using Xenopus to Understand Pluripotency
potential for therapeutical use. During the 70 years since the
frst NT experiments, we have uncovered a vast reserve of
knowledge that has aided the development of reprogramming
technology. SCNT can be applied to agriculture, namely to
aid in the preservation of endangered species. In hand with
the recently lauded gene-editing technology CRISPR, SCNT
can enable the production of cloned organisms with useful
traits such as disease resistance. Development of SCNT has
led to the ability to generate patient-derived NT embryonic
cells (ntESCs). The isogeneity of ntESCs eliminates the possibility of immune rejection, marking an exciting feat in the
therapeutic progress of this feld (Tachibana et al., 2013).
ntESCs could greatly aid in the development of cell replacement therapies and disease modeling. A decade after cloning
the frst mammal, we have been successful in cloning the f rst
non-human primate (Liu et al., 2018).
We have taken a signifcant leap from the initial in vivo
SCNT experiments carried out on Xenopus embryos to the
successful cloning of primates. SCNT has several advantages in comparison to other reprogramming techniques,
the chief advantage being its rapidity and the high quality
of stem cells that can be produced. However, there are still
several roadblocks to reprogramming that limit its translation into the clinic. Reprogramming effciency continues to
be low, which is the primary disadvantage in this technique,
followed closely by the ethical and practical limitations
that arise with theacquirement of human eggs. To improve
effciency, SCNT experiments into the Xenopus oocyte or
using Xenopus oocyte/egg extracts continue to be extremely
valuable model systems to study reprogramming factors and
factors causing resistance. In addition, understanding the
factors causing resistance of differentiated cells to nuclear
reprogramming will also reveal important safeguarding
mechanisms of cells, which help to maintain differentiated
cell identities in healthy organisms and that are impaired in
disease. The value of Xenopus as a model system for studying reprogramming continues to be noteworthy.
REFERENCES
Angelov, D., Molla, A., Perche, P.-Y., Hans, F., Côté, J., Khochbin,
S., Bouvet, P., & Dimitrov, S. (2003). The histone variant
macroH2A interferes with transcription factor binding and
SWI/SNF nucleosome remodeling. Molecular Cell, 11(4),
1033–1041. https://doi.org/10.1016/s1097-2765(03)00100-x
Blau, H. M., Chiu, C.-P., & Webster, C. (1983). Cytoplasmic activation
of human nuclear genes in stable heterocaryons. Cell, 32(4),
1171–1180. https://doi.org/10.1016/0092-8674(83)90300-8
Boiani, M., Eckardt, S., Schöler, H. R., & McLaughlin, K. J. (2002).
Oct4 distribution and level in mouse clones: Consequences
for pluripotency. Genes & Development, 16 (10), 1209–1219.
https://doi.org/10.1101/gad.966002
Bortvin, A., Eggan, K., Skaletsky, H., Akutsu, H., Berry, D. L.,
Yanagimachi, R., Page, D. C., & Jaenisch, R. (2003).
Incomplete reactivation of Oct4-related genes in mouse
embryos cloned from somatic nuclei. Development, 130(8),
1673–1680. https://doi.org/10.1242/dev.00366
Briggs, R., & King, T. J. (1952). Transplantation of living nuclei
from blastula cells into enucleated frogs’ eggs. Proceedings
of the National Academy of Sciences of the United States of
America, 38 (5), 455–463.
Campbell, K. H., McWhir, J., Ritchie, W. A., & Wilmut, I. (1996).
Sheep cloned by nuclear transfer from a cultured cell line.
Nature, 380 (6569), 64–66. https://doi.org/10.1038/380064a0
Chang, C.-C., Gao, S., Sung, L.-Y., Corry, G. N., Ma, Y., Nagy, Z.
P., Tian, X. C., & Rasmussen, T. P. (2010). Rapid elimination
of the histone variant MacroH2A from somatic cell heterochromatin after nuclear transfer. Cellular Reprogramming,
12 (1), 43–53. https://doi.org/10.1089/cell.2009.0043
Chung, Y. G., Matoba, S., Liu, Y., Eum, J. H., Lu, F., Jiang, W., Lee,
J. E., Sepilian, V., Cha, K. Y., Lee, D. R., & Zhang, Y. (2015).
Histone demethylase expression enhances human somatic
cell nuclear transfer effciency and promotes derivation
of pluripotent stem cells. Cell Stem Cell, 17(6), 758–766.
https://doi.org/10.1016/j.stem.2015.10.001
Davis, R. L., Weintraub, H., & Lassar, A. B. (1987).
Expression of a single transfected cDNA converts f broblasts to myoblasts. Cell, 51(6), 987–1000. https://doi.
org/10.1016/0092-8674(87)90585-x
Dean, W., Santos, F., Stojkovic, M., Zakhartchenko, V., Walter, J.,
Wolf, E., & Reik, W. (2001). Conservation of methylation
reprogramming in mammalian development: Aberrant reprogramming in cloned embryos. Proceedings of the National
Academy of Sciences, 98(24), 13734–13738. https://doi.
org/10.1073/pnas.241522698
De Robertis, E. M. D., & Gurdon, J. B. (1977). Gene activation
in somatic nuclei after injection into amphibian oocytes.
Proceedings of the National Academy of Sciences, 74(6),
2470–2474. https://doi.org/10.1073/pnas.74.6.2470
Elsdale, T. R., Gurdon, J. B., & Fischberg, M. (1960). A description of the technique for nuclear transplantation in Xenopus
laevis. Development, 8 (4), 437–444.
Evans, M. J., & Kaufman, M. H. (1981). Establishment in culture of
pluripotential cells from mouse embryos. Nature, 292(5819),
154–156. https://doi.org/10.1038/292154a0
Ganier, O., Bocquet, S., Peiffer, I., Brochard, V., Arnaud, P., Puy,
A., Jouneau, A., Feil, R., Renard, J.-P., & Méchali, M.
(2011). Synergic reprogramming of mammalian cells by
combined exposure to mitotic Xenopus egg extracts and
transcription factors. Proceedings of the National Academy
of Sciences, 108(42), 17331–17336. https://doi.org/10.1073/
pnas.1100733108
Gonzalez-Muñoz, E., Arboleda-Estudillo, Y., Otu, H. H., &
Cibelli, J. B. (2014). Histone chaperone ASF1A is required
for maintenance of pluripotency and cellular reprogramming. Science, 345(6198), 822–825. https://doi.org/10.1126/
science.1254745
Greenberg, M., & Bourc’his, D. (2019). The diverse roles of DNA
methylation in mammalian development and disease: Nature
reviews. Molecular Cell Biology, 20(10), 590–607. https://
doi.org/10.1038/s41580-019-0159-6
Gurdon, J. B. (1960). The developmental capacity of nuclei taken
from differentiating endoderm cells of Xenopus laevis. Journal
of Embryology and Experimental Morphology, 8, 505–526.
Gurdon, J. B. (1962). The developmental capacity of nuclei
taken from intestinal epithelium cells of feeding tadpoles.
Development, 10 (4), 622–640.
Gurdon, J. B., Elsdale, T. R., & Fischberg, M. (1958). Sexually
mature individuals of Xenopus laevis from the transplantation of single somatic nuclei. Nature, 182(4627), 64–65.
https://doi.org/10.1038/182064a0
Gurdon, J. B., & Uehlinger, V. (1966). “Fertile” intestine nuclei. Nature,
210(5042), 1240–1241. https://doi.org/10.1038/2101240a0
Using Xenopus to Understand Pluripotency
potential for therapeutical use. During the 70 years since the
frst NT experiments, we have uncovered a vast reserve of
knowledge that has aided the development of reprogramming
technology. SCNT can be applied to agriculture, namely to
aid in the preservation of endangered species. In hand with
the recently lauded gene-editing technology CRISPR, SCNT
can enable the production of cloned organisms with useful
traits such as disease resistance. Development of SCNT has
led to the ability to generate patient-derived NT embryonic
cells (ntESCs). The isogeneity of ntESCs eliminates the possibility of immune rejection, marking an exciting feat in the
therapeutic progress of this feld (Tachibana et al., 2013).
ntESCs could greatly aid in the development of cell replacement therapies and disease modeling. A decade after cloning
the frst mammal, we have been successful in cloning the f rst
non-human primate (Liu et al., 2018).
We have taken a signifcant leap from the initial in vivo
SCNT experiments carried out on Xenopus embryos to the
successful cloning of primates. SCNT has several advantages in comparison to other reprogramming techniques,
the chief advantage being its rapidity and the high quality
of stem cells that can be produced. However, there are still
several roadblocks to reprogramming that limit its translation into the clinic. Reprogramming effciency continues to
be low, which is the primary disadvantage in this technique,
followed closely by the ethical and practical limitations
that arise with theacquirement of human eggs. To improve
effciency, SCNT experiments into the Xenopus oocyte or
using Xenopus oocyte/egg extracts continue to be extremely
valuable model systems to study reprogramming factors and
factors causing resistance. In addition, understanding the
factors causing resistance of differentiated cells to nuclear
reprogramming will also reveal important safeguarding
mechanisms of cells, which help to maintain differentiated
cell identities in healthy organisms and that are impaired in
disease. The value of Xenopus as a model system for studying reprogramming continues to be noteworthy.
REFERENCES
Angelov, D., Molla, A., Perche, P.-Y., Hans, F., Côté, J., Khochbin,
S., Bouvet, P., & Dimitrov, S. (2003). The histone variant
macroH2A interferes with transcription factor binding and
SWI/SNF nucleosome remodeling. Molecular Cell, 11(4),
1033–1041. https://doi.org/10.1016/s1097-2765(03)00100-x
Blau, H. M., Chiu, C.-P., & Webster, C. (1983). Cytoplasmic activation
of human nuclear genes in stable heterocaryons. Cell, 32(4),
1171–1180. https://doi.org/10.1016/0092-8674(83)90300-8
Boiani, M., Eckardt, S., Schöler, H. R., & McLaughlin, K. J. (2002).
Oct4 distribution and level in mouse clones: Consequences
for pluripotency. Genes & Development, 16 (10), 1209–1219.
https://doi.org/10.1101/gad.966002
Bortvin, A., Eggan, K., Skaletsky, H., Akutsu, H., Berry, D. L.,
Yanagimachi, R., Page, D. C., & Jaenisch, R. (2003).
Incomplete reactivation of Oct4-related genes in mouse
embryos cloned from somatic nuclei. Development, 130(8),
1673–1680. https://doi.org/10.1242/dev.00366
Briggs, R., & King, T. J. (1952). Transplantation of living nuclei
from blastula cells into enucleated frogs’ eggs. Proceedings
of the National Academy of Sciences of the United States of
America, 38 (5), 455–463.
Campbell, K. H., McWhir, J., Ritchie, W. A., & Wilmut, I. (1996).
Sheep cloned by nuclear transfer from a cultured cell line.
Nature, 380 (6569), 64–66. https://doi.org/10.1038/380064a0
Chang, C.-C., Gao, S., Sung, L.-Y., Corry, G. N., Ma, Y., Nagy, Z.
P., Tian, X. C., & Rasmussen, T. P. (2010). Rapid elimination
of the histone variant MacroH2A from somatic cell heterochromatin after nuclear transfer. Cellular Reprogramming,
12 (1), 43–53. https://doi.org/10.1089/cell.2009.0043
Chung, Y. G., Matoba, S., Liu, Y., Eum, J. H., Lu, F., Jiang, W., Lee,
J. E., Sepilian, V., Cha, K. Y., Lee, D. R., & Zhang, Y. (2015).
Histone demethylase expression enhances human somatic
cell nuclear transfer effciency and promotes derivation
of pluripotent stem cells. Cell Stem Cell, 17(6), 758–766.
https://doi.org/10.1016/j.stem.2015.10.001
Davis, R. L., Weintraub, H., & Lassar, A. B. (1987).
Expression of a single transfected cDNA converts f broblasts to myoblasts. Cell, 51(6), 987–1000. https://doi.
org/10.1016/0092-8674(87)90585-x
Dean, W., Santos, F., Stojkovic, M., Zakhartchenko, V., Walter, J.,
Wolf, E., & Reik, W. (2001). Conservation of methylation
reprogramming in mammalian development: Aberrant reprogramming in cloned embryos. Proceedings of the National
Academy of Sciences, 98(24), 13734–13738. https://doi.
org/10.1073/pnas.241522698
De Robertis, E. M. D., & Gurdon, J. B. (1977). Gene activation
in somatic nuclei after injection into amphibian oocytes.
Proceedings of the National Academy of Sciences, 74(6),
2470–2474. https://doi.org/10.1073/pnas.74.6.2470
Elsdale, T. R., Gurdon, J. B., & Fischberg, M. (1960). A description of the technique for nuclear transplantation in Xenopus
laevis. Development, 8 (4), 437–444.
Evans, M. J., & Kaufman, M. H. (1981). Establishment in culture of
pluripotential cells from mouse embryos. Nature, 292(5819),
154–156. https://doi.org/10.1038/292154a0
Ganier, O., Bocquet, S., Peiffer, I., Brochard, V., Arnaud, P., Puy,
A., Jouneau, A., Feil, R., Renard, J.-P., & Méchali, M.
(2011). Synergic reprogramming of mammalian cells by
combined exposure to mitotic Xenopus egg extracts and
transcription factors. Proceedings of the National Academy
of Sciences, 108(42), 17331–17336. https://doi.org/10.1073/
pnas.1100733108
Gonzalez-Muñoz, E., Arboleda-Estudillo, Y., Otu, H. H., &
Cibelli, J. B. (2014). Histone chaperone ASF1A is required
for maintenance of pluripotency and cellular reprogramming. Science, 345(6198), 822–825. https://doi.org/10.1126/
science.1254745
Greenberg, M., & Bourc’his, D. (2019). The diverse roles of DNA
methylation in mammalian development and disease: Nature
reviews. Molecular Cell Biology, 20(10), 590–607. https://
doi.org/10.1038/s41580-019-0159-6
Gurdon, J. B. (1960). The developmental capacity of nuclei taken
from differentiating endoderm cells of Xenopus laevis. Journal
of Embryology and Experimental Morphology, 8, 505–526.
Gurdon, J. B. (1962). The developmental capacity of nuclei
taken from intestinal epithelium cells of feeding tadpoles.
Development, 10 (4), 622–640.
Gurdon, J. B., Elsdale, T. R., & Fischberg, M. (1958). Sexually
mature individuals of Xenopus laevis from the transplantation of single somatic nuclei. Nature, 182(4627), 64–65.
https://doi.org/10.1038/182064a0
Gurdon, J. B., & Uehlinger, V. (1966). “Fertile” intestine nuclei. Nature,
210(5042), 1240–1241. https://doi.org/10.1038/2101240a0