Chromatin tethering to the nuclear envelope by nuclear actin filaments: a novel role of the actin cytoskeleton in the Xenopus blastula.
The Xenopus oocyte is known to accumulate filamentous or F-actin in the nucleus, but it is currently unknown whether F-actin also accumulates in embryo nuclei. Using fluorescence-labeled actin reporters, we examined the actin distribution in Xenopus embryonic cells and found that F-actin accumulates in nuclei during the blastula stage but not during the gastrula stage. To further investigate nuclear F-actin, we devised a Xenopus egg extract that reproduces the formation of nuclei in which F-actin accumulates. Using this extract, we found that F-actin accumulates primarily at the subnuclear membranous region and is essential to maintain chromatin binding to the nuclear envelope in well-developed nuclei. We also provide evidence that nuclear F-actin increases the structural stability of nuclei and contributes to chromosome alignment on the mitotic spindle at the following M phase. These results suggest the physiological importance of nuclear F-actin accumulation in rapidly dividing large Xenopus blastula cells.
Group of Developmental Cell Biology, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan.
Haruka
H
Oda
Group of Developmental Cell Biology, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan.
Natsuki
N
Shirai
Group of Developmental Cell Biology, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan.
Naoko
N
Ura
Group of Developmental Cell Biology, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan.
Keita
K
Ohsumi
Group of Developmental Cell Biology, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, 464-8602, Japan.
Mari
http://orcid.org/0000-0003-1956-7966
M
Iwabuchi
D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D000818:Animals; D036703:Blastula / Q000166:cytology* / Q000378:metabolism; D002474:Cell-Free System; D002843:Chromatin / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000378:metabolism; D009685:Nuclear Envelope / Q000378:metabolism*; D010063:Ovum / Q000166:cytology / Q000378:metabolism; D014982:Xenopus laevis / Q000196:embryology / Q000378:metabolism*
D000199:Actins; D002843:Chromatin