Dynamic associations of heterochromatin protein 1 with the nuclear envelope.
To study the dynamics of mammalian HP1 proteins we have microinjected recombinant forms of mHP1alpha, M31 and M32 into the cytoplasm of living cells. As could be expected from previous studies, the three fusion proteins were efficiently transported into the nucleus and targeted specific chromatin areas. However, before incorporation into these areas the exogenous proteins accumulated in a peripheral zone and associated closely with the nuclear envelope. This transient association did not occur when the cells were treated with deacetylase inhibitors, indicating an acetylation-inhibited interaction. In line with these observations, recombinant HP1 proteins exhibited saturable binding to purified nuclear envelopes and stained the nuclei of detergent-permeabilized cells in a rim-like fashion. Competition experiments with various M31 mutants allowed mapping of the nuclear envelope-binding site within an N-terminal region that includes the chromodomain. A His(6)-tagged peptide representing this region inhibited recruitment of LAP2beta and B-type lamins around the surfaces of condensed chromosomes, suggesting involvement of HP1 proteins in nuclear envelope reassembly.
Kourmouli
N
N
Department of Basic Sciences, The University of Crete School of Medicine, 71 110 Heraklion, Crete, Greece.
Theodoropoulos
P A
PA
Dialynas
G
G
Bakou
A
A
Politou
A S
AS
Cowell
I G
IG
Singh
P B
PB
Georgatos
S D
SD
D000107:Acetylation; D000818:Animals; D001665:Binding Sites; D001667:Binding, Competitive; D016466:CHO Cells; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D000090266:Chromobox Protein Homolog 5; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002875:Chromosomes / Q000378:metabolism; D006224:Cricetinae; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins; D003902:Detergents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D019084:Fluorescent Antibody Technique, Indirect; D005982:Glutathione Transferase / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D015151:Immunoblotting; D007700:Kinetics; D034882:Lamins; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D008845:Microinjections; D008938:Mitosis; D009154:Mutation; D009685:Nuclear Envelope / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D017830:Octoxynol / Q000494:pharmacology; D011485:Protein Binding; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000502:physiology
D002843:Chromatin; D002868:Chromosomal Proteins, Non-Histone; D004268:DNA-Binding Proteins; D003902:Detergents; D034882:Lamins; D008565:Membrane Proteins; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; C093413:lamina-associated polypeptide 2; D000090266:Chromobox Protein Homolog 5; D017830:Octoxynol; D005982:Glutathione Transferase