scholarly journals Maturation-promoting factor induces nuclear envelope breakdown in cycloheximide-arrested embryos of Xenopus laevis.

1983 ◽  
Vol 97 (1) ◽  
pp. 81-91 ◽  
Author(s):  
R Miake-Lye ◽  
J Newport ◽  
M Kirschner
Keyword(s):  
Xenopus Laevis ◽  
Nuclear Envelope ◽  
Nuclear Lamina ◽  
Embryonic Cell ◽  
Immunofluorescent Staining ◽  
Interphase Nuclei ◽  
Nuclear Envelope Breakdown ◽  
G2 Phase ◽  
Embryonic Cell Cycle ◽  
Maturation Promoting Factor

We have studied the effect of maturation-promoting factor (MPF) on embryonic nuclei during the early cleavage stage of Xenopus laevis development. When protein synthesis is inhibited by cycloheximide during this stage, the embryonic cell cycle arrests in an artificially produced G2 phase-like state, after completion of one additional round of DNA synthesis. Approximately 100 nuclei can be arrested in a common cytoplasm if cytokinesis is first inhibited by cytochalasin B. Within 5 min after injection of MPF into such embryos, the nuclear envelope surrounding each nucleus disperses, as determined histologically or by immunofluorescent staining of the nuclear lamina with antilamin antiserum. The breakdown of the nuclear envelope occurs at levels of MPF comparable to or slightly lower than those required for oocyte maturation. Amplification of MPF activity, however, does not occur in the arrested egg as it does in the oocyte. These results suggest that MPF can act to advance interphase nuclei into the first events of mitosis and show that the nuclear lamina responds rapidly to MPF.

scholarly journals Remodeling of mouse thymocyte nuclei depends on the time of their transfer into activated, homologous oocytes

1988 ◽  
Vol 91 (4) ◽  
pp. 603-613
Author(s):  
D. Szollosi ◽  
R. Czolowska ◽  
M.S. Szollosi ◽  
A.K. Tarkowski
Keyword(s):  
Nuclear Envelope ◽  
Somatic Cell ◽  
Morphological Changes ◽  
Factor Activity ◽  
Cell Nuclei ◽  
Nuclear Envelope Breakdown ◽  
Somatic Cell Nucleus ◽  
Short Time ◽  
Nuclear Remodeling ◽  
Maturation Promoting Factor

The potential of parthenogenetically activated mouse oocytes to remodel somatic cell nuclei was studied by ultrastructural means using oocyte-thymocyte hybrids. Complete nuclear remodeling, initiated by nuclear envelope breakdown and chromosome condensation (which is followed by formation of pronucleus-like nucleus) is possible only during a short time gap between metaphase II and telophase of meiotic division. Maturation-promoting factor activity is high during this period. The thymocyte nucleus can follow the sequence of morphological changes only in concert with the development of the native nucleus and only after exposure of the chromatin to the ooplasm. If hybridization is effected with pronucleate oocytes, the thymocyte nucleus retains its interphase character but shows particular modifications in nucleolar morphology (identical to changes observed during reactivation of the nucleolus in stimulated lymphocyte) and in the activity of the nuclear envelope (blebbing). Thus the nucleus not exposed to maturation-promoting factor activity may be influenced by a ‘programme’ specific for oocyte (blebbing) and by a programme inherent in the introduced somatic cell nucleus.

Metaphase protein phosphorylation in Xenopus laevis eggs

1987 ◽  
Vol 7 (2) ◽  
pp. 760-768
Author(s):  
M J Lohka ◽  
J L Kyes ◽  
J L Maller
Keyword(s):  
Xenopus Laevis ◽  
Nuclear Envelope ◽  
Protein Phosphorylation ◽  
Tyrosine Kinases ◽  
Chromosome Condensation ◽  
Nuclear Envelope Breakdown ◽  
M Phase ◽  
Nuclear Events ◽  
Gamma S

Cytoplasmic extracts of metaphase (M-phase)-arrested Xenopus laevis eggs support nuclear envelope breakdown and chromosome condensation in vitro. Induction of nuclear breakdown is inhibited by AMPP(NH)P, a nonhydrolyzable ATP analog, but not by ATP or gamma-S-ATP, a hydrolyzable ATP analog, suggesting that protein phosphorylation may be required for M-phase nuclear events in vitro. By addition of [gamma-32P]ATP, we have identified in cytoplasmic extracts and in intact eggs at least six phosphoproteins that are present during M-phase but absent in G1/S-phase. These phosphoproteins also appear in response to partially purified preparations of maturation-promoting factor. A subset of these proteins are thiophosphorylated by gamma-S-ATP under conditions that promote nuclear envelope breakdown and chromosome condensation. Each of these proteins is phosphorylated on serine and threonine, and one, a 42-kilodalton protein, is also phosphorylated on tyrosine both in extracts and in intact eggs. These results indicate that activation of protein kinases accounts for at least part of the increased phosphorylation in M-phase and that both protein-serine-threonine kinases and protein-tyrosine kinases may play a role in controlling M-phase nuclear behavior.

scholarly journals A carboxyl-terminal interaction of lamin B1 is dependent on the CAAX endoprotease Rce1 and carboxymethylation

2003 ◽  
Vol 162 (7) ◽  
pp. 1223-1232 ◽  
Author(s):  
Christopher P. Maske ◽  
Michael S. Hollinshead ◽  
Niall C. Higbee ◽  
Martin O. Bergo ◽  
Stephen G. Young ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Lamina ◽  
Potential Mechanism ◽  
Interphase Nuclei ◽  
Lamin B1 ◽  
Carboxyl Terminal ◽  
Caax Motif

The mammalian nuclear lamina protein lamin B1 is posttranslationally modified by farnesylation, endoproteolysis, and carboxymethylation at a carboxyl-terminal CAAX motif. In this work, we demonstrate that the CAAX endoprotease Rce1 is required for lamin B1 endoproteolysis, demonstrate an independent pool of proteolyzed but nonmethylated lamin B1, as well as fully processed lamin B1, in interphase nuclei, and show a role for methylation in the organization of lamin B1 into domains of the nuclear lamina. Deficiency in the endoproteolysis or methylation of lamin B1 results in loss of integrity and deformity of the nuclear lamina. These data show that the organization of the nuclear envelope and lamina is dependent on a mechanism involving the methylation of lamin B1, and they identify a potential mechanism of laminopathy involving a B-type lamin.

scholarly journals Nuclear Envelope Breakdown Requires Overcoming the Mechanical Integrity of the Nuclear Lamina

2004 ◽  
Vol 279 (42) ◽  
pp. 43462-43467 ◽  
Author(s):  
Porntula Panorchan ◽  
Benjamin W. Schafer ◽  
Denis Wirtz ◽  
Yiider Tseng
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Lamina ◽  
Mechanical Integrity ◽  
Nuclear Envelope Breakdown

Sequential PKC- and Cdc2-mediated phosphorylation events elicit zebrafish nuclear envelope disassembly

1999 ◽  
Vol 112 (6) ◽  
pp. 977-987 ◽  
Author(s):  
P. Collas
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Nuclear Lamina ◽  
Cdc2 Kinase ◽  
Lamin B ◽  
Inner Nuclear Membrane ◽  
Nuclear Envelope Breakdown ◽  
Simultaneous Inhibition ◽  
Integral Proteins

Molecular markers of the zebrafish inner nuclear membrane (NEP55) and nuclear lamina (L68) were identified, partially characterized and used to demonstrate that disassembly of the zebrafish nuclear envelope requires sequential phosphorylation events by first PKC, then Cdc2 kinase. NEP55 and L68 are immunologically and functionally related to human LAP2beta and lamin B, respectively. Exposure of zebrafish nuclei to meiotic cytosol elicits rapid phosphorylation of NEP55 and L68, and disassembly of both proteins. L68 phosphorylation is completely inhibited by simultaneous inhibition of Cdc2 and PKC and only partially blocked by inhibition of either kinase. NEP55 phosphorylation is completely prevented by inhibition or immunodepletion of cytosolic Cdc2. Inhibition of cAMP-dependent kinase, MEK or CaM kinase II does not affect NEP55 or L68 phosphorylation. In vitro, nuclear envelope disassembly requires phosphorylation of NEP55 and L68 by both mammalian PKC and Cdc2. Inhibition of either kinase is sufficient to abolish NE disassembly. Furthermore, novel two-step phosphorylation assays in cytosol and in vitro indicate that PKC-mediated phosphorylation of L68 prior to Cdc2-mediated phosphorylation of L68 and NEP55 is essential to elicit nuclear envelope breakdown. Phosphorylation elicited by Cdc2 prior to PKC prevents nuclear envelope disassembly even though NEP55 is phosphorylated. The results indicate that sequential phosphorylation events elicited by PKC, followed by Cdc2, are required for zebrafish nuclear disassembly. They also argue that phosphorylation of inner nuclear membrane integral proteins is not sufficient to promote nuclear envelope breakdown, and suggest a multiple-level regulation of disassembly of nuclear envelope components during meiosis and at mitosis.

Decondensation of the mouse sperm nucleus within the interphase nucleus

Zygote ◽  
1998 ◽  
Vol 6 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Yasutaka Maeda ◽  
Hiroko Yanagimachi ◽  
Hiroyuki Tateno ◽  
Noriko Usui ◽  
R. Yanagimachi
Keyword(s):  
Nuclear Envelope ◽  
Interphase Nucleus ◽  
Sperm Nucleus ◽  
Interphase Nuclei ◽  
Mouse Sperm ◽  
Immature Oocytes ◽  
Nuclear Envelope Breakdown ◽  
Germinal Vesicles ◽  
Sperm Nuclei ◽  
Mouse Eggs

SummarySperm nuclei incorporated into the cytoplasm (ooplasm) of fertilised mouse eggs at the pronuclear stage remain condensed, whereas those injected into male or female pronuclei decondense. Similarly, sperm nuclei injected into germinal vesicles of immature oocytes or the nuclei of 2-cell embryos decondense, while those entering the cytoplasm of these oocytes / embryos do not. These facts seem to suggest that factors necessary for the decondensation of sperm nucleus are present in interphase nuclei and are released into the ooplasm during nuclear envelope breakdown. Nucleoplasmin, which is synthesised in the cytoplasm and accumulated within the nucleus, is likely a major candidate for these factors.

scholarly journals Identification of a Golgi-associated protein that undergoes mitosis dependent phosphorylation and relocation.

1990 ◽  
Vol 110 (5) ◽  
pp. 1513-1523 ◽  
Author(s):  
I McMorrow ◽  
W E Souter ◽  
G Plopper ◽  
B Burke
Keyword(s):  
Monoclonal Antibody ◽  
Nuclear Envelope ◽  
Immunofluorescence Microscopy ◽  
Nuclear Lamina ◽  
Early Prophase ◽  
Perinuclear Region ◽  
Nuclear Envelope Breakdown ◽  
Peripheral Membrane Protein ◽  
Double Label ◽  
Late Telophase

By means of a monoclonal antibody (BH3), we have identified a 57-kD protein (p57) that in interphase is restricted largely to the perinuclear region of the cell. Double label immunofluorescence microscopy suggests localization of p57 to the Golgi complex and associated membranous structures. Protease protection experiments and chemical extractability indicate that p57 is a peripheral membrane protein exposed to the cytoplasm. p57 displays unique behavior during mitosis. At the end of G2 or in early prophase, p57 leaves the perinuclear region and accumulates very rapidly within the nucleus, at a time when the nuclear envelope is still intact and before nuclear lamina disassembly. This relocation of p57 coincides with its hyperphosphorylation on serine and threonine residues. After nuclear envelope breakdown p57 becomes uniformly distributed throughout the mitotic cytoplasm until in late telophase when it returns to its perinuclear location and is once again excluded from the nucleus. The behavior of p57 during mitosis suggests that it may play a role in the cellular reorganization evident during mitotic prophase.

The structure and function of the nuclear lamins

1995 ◽  
Vol 53 ◽  
pp. 762-763
Author(s):  
R.D. Goldman ◽  
A. Goldman ◽  
S. Khuon ◽  
M. Montag-Lowy ◽  
R. Moir ◽  
...  
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Lamina ◽  
Structure And Function ◽  
Supramolecular Organization ◽  
Intermediate Filament Proteins ◽  
Nuclear Envelope Breakdown ◽  
Nuclear Lamins ◽  
Interphase Cells ◽  
Type V ◽  
And Function

The nuclear lamins are the Type V intermediate filament proteins comprising the nuclear lamina. The lamina is located subjacent to the nucleoplasmic face of the nuclear envelope where it interfaces with chromatin. The lamins are major karyoskeletal proteins which are thought to play important roles in the formation and maintenance of nuclear shape and architecture, as well as in the supramolecular organization of chromatin. The lamins have long been thought to be stable polymeric constituents of the interphase nuclear matrix, due to their insolubility in solutions containing detergents and high salt concentrations. During mitosis, however, the nuclear lamins depolymerize during nuclear envelope breakdown. Subsequently, the lamins repolymerize around the decondensing chromosomes as the nuclear envelope reassembles at the end of mitosis. Although there is a significant amount known about the properties and potential functions of the lamins during mitosis, surprisingly little is known about their properties during interphase. In light of this, we have undertaken experiments which are aimed at determining the properties of the lamins in interphase cells.

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