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A role for nuclear lamins in nuclear envelope assembly.

Lopez-Soler RI, Moir RD, Spann TP, Stick R, Goldman RD - J. Cell Biol. (2001)

Bottom Line: LB3T also binds to chromatin in the absence of interphase extract, but only in the presence of purified LB3.Additionally, we show that LB3T inhibits normal lamin polymerization in vitro.These findings suggest that lamin polymerization is required for both chromatin decondensation and the binding of nuclear membrane precursors during the early stages of normal nuclear envelope assembly.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell and Molecular Biology, Northwestern University Medical School, 303 East Chicago Avenue, Chicago, IL 60611, USA.

ABSTRACT
The molecular interactions responsible for nuclear envelope assembly after mitosis are not well understood. In this study, we demonstrate that a peptide consisting of the COOH-terminal domain of Xenopus lamin B3 (LB3T) prevents nuclear envelope assembly in Xenopus interphase extracts. Specifically, LB3T inhibits chromatin decondensation and blocks the formation of both the nuclear lamina-pore complex and nuclear membranes. Under these conditions, some vesicles bind to the peripheral regions of the chromatin. These "nonfusogenic" vesicles lack lamin B3 (LB3) and do not bind LB3T; however, "fusogenic" vesicles containing LB3 can bind LB3T, which blocks their association with chromatin and, subsequently, nuclear membrane assembly. LB3T also binds to chromatin in the absence of interphase extract, but only in the presence of purified LB3. Additionally, we show that LB3T inhibits normal lamin polymerization in vitro. These findings suggest that lamin polymerization is required for both chromatin decondensation and the binding of nuclear membrane precursors during the early stages of normal nuclear envelope assembly.

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Electron microscopy analysis of LB3T-treated and control nuclei. In the presence of LB3T, only membrane vesicles are found along the surface of condensed chromatin (A). In controls, decondensed chromatin masses surrounded by typical double membranes with nuclear pore complexes are seen (B, arrows). Bars, 2 μm.
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fig2: Electron microscopy analysis of LB3T-treated and control nuclei. In the presence of LB3T, only membrane vesicles are found along the surface of condensed chromatin (A). In controls, decondensed chromatin masses surrounded by typical double membranes with nuclear pore complexes are seen (B, arrows). Bars, 2 μm.

Mentions: Electron microscopic analyses of 50 sperm heads incubated in extracts containing LB3T (see Materials and methods) revealed the absence of double membrane/pore complexes that typify normal nuclear envelopes (Fig. 2 A). Instead, only a small number of membrane vesicles appeared in the peripheral region of the condensed chromatin in LB3T-treated preparations (compare Fig. 2, A and B). These results also confirm that LB3T blocks the formation of double membranes and pore complexes around chromatin.


A role for nuclear lamins in nuclear envelope assembly.

Lopez-Soler RI, Moir RD, Spann TP, Stick R, Goldman RD - J. Cell Biol. (2001)

Electron microscopy analysis of LB3T-treated and control nuclei. In the presence of LB3T, only membrane vesicles are found along the surface of condensed chromatin (A). In controls, decondensed chromatin masses surrounded by typical double membranes with nuclear pore complexes are seen (B, arrows). Bars, 2 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2196852&req=5

fig2: Electron microscopy analysis of LB3T-treated and control nuclei. In the presence of LB3T, only membrane vesicles are found along the surface of condensed chromatin (A). In controls, decondensed chromatin masses surrounded by typical double membranes with nuclear pore complexes are seen (B, arrows). Bars, 2 μm.
Mentions: Electron microscopic analyses of 50 sperm heads incubated in extracts containing LB3T (see Materials and methods) revealed the absence of double membrane/pore complexes that typify normal nuclear envelopes (Fig. 2 A). Instead, only a small number of membrane vesicles appeared in the peripheral region of the condensed chromatin in LB3T-treated preparations (compare Fig. 2, A and B). These results also confirm that LB3T blocks the formation of double membranes and pore complexes around chromatin.

Bottom Line: LB3T also binds to chromatin in the absence of interphase extract, but only in the presence of purified LB3.Additionally, we show that LB3T inhibits normal lamin polymerization in vitro.These findings suggest that lamin polymerization is required for both chromatin decondensation and the binding of nuclear membrane precursors during the early stages of normal nuclear envelope assembly.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell and Molecular Biology, Northwestern University Medical School, 303 East Chicago Avenue, Chicago, IL 60611, USA.

ABSTRACT
The molecular interactions responsible for nuclear envelope assembly after mitosis are not well understood. In this study, we demonstrate that a peptide consisting of the COOH-terminal domain of Xenopus lamin B3 (LB3T) prevents nuclear envelope assembly in Xenopus interphase extracts. Specifically, LB3T inhibits chromatin decondensation and blocks the formation of both the nuclear lamina-pore complex and nuclear membranes. Under these conditions, some vesicles bind to the peripheral regions of the chromatin. These "nonfusogenic" vesicles lack lamin B3 (LB3) and do not bind LB3T; however, "fusogenic" vesicles containing LB3 can bind LB3T, which blocks their association with chromatin and, subsequently, nuclear membrane assembly. LB3T also binds to chromatin in the absence of interphase extract, but only in the presence of purified LB3. Additionally, we show that LB3T inhibits normal lamin polymerization in vitro. These findings suggest that lamin polymerization is required for both chromatin decondensation and the binding of nuclear membrane precursors during the early stages of normal nuclear envelope assembly.

Show MeSH
Related in: MedlinePlus