Key points are not available for this paper at this time.
Replicated mammalian chromosomes condense to segregate during anaphase, and they de-condense at the conclusion of mitosis. Currently, it is not understood what the factors and events are that specify de-condensation. Here, we demonstrate that chromosome de-condensation needs the function of an inner nuclear membrane (INM) protein hsSUN1 and a membrane-associated histone acetyltransferase (HAT), hALP. We propose that nascently reforming nuclear envelope employs hsSUN1 and hALP to acetylate histones for de-compacting DNA at the end of mitosis. Replicated mammalian chromosomes condense to segregate during anaphase, and they de-condense at the conclusion of mitosis. Currently, it is not understood what the factors and events are that specify de-condensation. Here, we demonstrate that chromosome de-condensation needs the function of an inner nuclear membrane (INM) protein hsSUN1 and a membrane-associated histone acetyltransferase (HAT), hALP. We propose that nascently reforming nuclear envelope employs hsSUN1 and hALP to acetylate histones for de-compacting DNA at the end of mitosis. The eukaryotic nucleus is separated from other organelles by an envelope containing two membrane layers continuous with the endoplasmic reticulum. Nuclear membrane proteins fall into three categories according to their localization. The first group is the trans-nuclear membrane proteins resident in the nuclear pore complex (NPC). 2The abbreviations used are:NPCnuclear pore complexSUNSad1-UNC84ChIPchromatin immunoprecipitationINMinner nuclear membraneH3pSer10phosphorylated histone H3 at serine 10hALPhuman acetyl-transferase-like proteinLAPlamin-associated polypeptideLBRlamin B receptorHAThistone acetyltransferaseHDAChistone deacetylaseORFopen reading frameRIPAradioimmune precipitation assay bufferPBSphosphate-buffered salineGSTglutathione S-transferaseHAhemagglutininDAPI4′,6-diamidino-2-phenylindoleGFPgreen fluorescent proteinWTwild type 2The abbreviations used are:NPCnuclear pore complexSUNSad1-UNC84ChIPchromatin immunoprecipitationINMinner nuclear membraneH3pSer10phosphorylated histone H3 at serine 10hALPhuman acetyl-transferase-like proteinLAPlamin-associated polypeptideLBRlamin B receptorHAThistone acetyltransferaseHDAChistone deacetylaseORFopen reading frameRIPAradioimmune precipitation assay bufferPBSphosphate-buffered salineGSTglutathione S-transferaseHAhemagglutininDAPI4′,6-diamidino-2-phenylindoleGFPgreen fluorescent proteinWTwild type The second group contains the inner membrane proteins (INM), which include the lamin B receptor (LBR), emerin, and lamin-associated The group proteins the nuclear membrane nuclear the a the for the of the nucleus and the and the nuclear a which nuclear and in DNA and proteins are with the nuclear a of in to reading of to chromosome to a of from and and in emerin, lamin and lamin B receptor with is that the proteins are to nuclear and that to the of a of in nuclear membrane to to proteins a at their The first the of of and of proteins that they to at during the at and to function in the of the the other in the nuclear envelope a and a other a to is the function of mammalian proteins the of nuclear membrane at the end of to to chromosome we the for We that hsSUN1 is of the factors to with chromosomes in of hsSUN1 to histones and de-condensation of chromosomes at the end of mitosis. to with mammalian inner nuclear membrane to hsSUN1 and to for chromosome de-condensation. a used by nascently to for in the and hALP from the DNA hsSUN1 from the and into hsSUN1 and and by the by and into hALP by and with for in the protein used for hsSUN1 first with protein and protein to in containing and with and with from the and with and containing the by to and to with of protein and proteins to with in and and the by the assay by the by with by to the and for at The by of and at for with and by and in and and for for and at at for of in in and with for at The with the with in of for to the and in for at and with in for at with in for lamin B nuclear pore complex and to at of to and for at three with and with fluorescent with the with a at in a with hsSUN1 and hALP from with hsSUN1 with hsSUN1 to We with the by of hsSUN1 to the Nuclear to from to for DNA from DNA and from of not from and that hsSUN1 is in hsSUN1 with a that hsSUN1 three at and and two at and that hsSUN1 is an not which hsSUN1 nuclear DNA we hsSUN1 and in We that hsSUN1 of and a nuclear envelope that hsSUN1 is for nuclear membrane localization. we into hsSUN1 in hsSUN1 of the protein from the nuclear envelope into the of three of with from the the first from hsSUN1 of the protein from the envelope into the the not the to hsSUN1 the hsSUN1 three and first are for in the nuclear Nuclear are not we and to hsSUN1 we first the of hsSUN1 with lamin the nucleus the envelope with lamin and emerin, is at the nuclear hsSUN1 and the nuclear pore complex with which the in are the into lamin and into the with is anaphase, hsSUN1 nascently separated at the of chromosomes the of hsSUN1 and We that hsSUN1 from to of lamin and lamin to and by lamin with hsSUN1 at nuclear other are that hsSUN1 and lamin in of of the of in with an of proteins and with and to lamin emerin, and and are DNA with two and of with hsSUN1 and an of hsSUN1 at the of chromosomes in in to hsSUN1 at the of to hsSUN1 lamin in chromosomes and proteins with in their with chromosomes We the hsSUN1 with to the of hsSUN1 and we hsSUN1 and and are in hsSUN1 and anaphase, hsSUN1 at the of chromosomes with to chromosome and hsSUN1 with chromosomes to of hsSUN1 and in and first at the of separated by with by DNA with of of and are in are in The of and are assay and are with and by by is that a which other proteins to a nuclear and with chromosomes we a We and and that a are we type hsSUN1 and the hsSUN1 and a precipitation assay a the used in a assay and histone and by a protein containing the hsSUN1 not a in the of for hsSUN1 Nuclear we the for hsSUN1 in nuclear envelope into with a fluorescent protein from and hsSUN1 protein to from the not the to in the nucleus in to and the protein a in and a nuclear envelope in which to of hsSUN1 nuclear envelope and of from with of hsSUN1 and with used a with a and and with is hsSUN1 is and DNA is with and and and used to nuclear envelope we for in for hsSUN1 and at the of DNA in hsSUN1 to in for the of nuclear envelope to and events at the end of and chromosomes Currently, it is two events are the nuclear envelope DNA we chromosome in and hsSUN1 We from chromosomes to DNA and with at the during by and the fluorescent is in hsSUN1 nuclear envelope and in an in DNA of hsSUN1 with with to hsSUN1 and and and DNA with and and of DNA in and by a of to and at the of are of in with of are of and and and in from with by a of in histone histone H3 histone in by a of to the by and at in DNA from a in de-condensation of We in with and a fluorescent histone in the of fluorescent chromosomes in chromosomes in hsSUN1 We of of of in and of of to and to the other with and not of and in to what for chromosome de-condensation in chromosomes are by histones function is by and other events of histone H3 at serine to the other what de-condensation is in and not hsSUN1 and that not in to factors to DNA We histone DNA de-condensation. the of histones in and hsSUN1 by a of for and and with an for and in the other H3 We in and for at and not at of and for at and of that of hsSUN1 not nuclear envelope and chromosome de-condensation and the of and and to that chromosome de-condensation is to a histone acetyltransferase which we that a a nuclear membrane-associated in that the a of is a nuclear membrane-associated protein hALP with hALP with chromosome in a is with hALP a for with we used to hALP B and and in DNA chromosome in with of hALP DNA of hALP with with with DNA with is in of hALP and with of hALP in and by used of of protein by to of in with of are of and and in hALP to from is that chromosomes they by nuclear envelope the of which membrane-associated hALP to DNA which that hsSUN1 hALP to chromosome by a protein with the of hsSUN1 to hALP. is that an and DNA an of an of with hALP contains the hsSUN1 and inner membrane-associated We hALP with into of the three we of in hALP of of de-condensation from and of of DNA of and and hALP function in chromosome de-condensation. of and of with of are from and by from the protein are with hsSUN1 hALP with an by hsSUN1 and we hALP. a we used a of which contains from and that hALP with not for a hsSUN1 is in to other three Here, we that the hsSUN1 three are for nuclear membrane and that is for that hsSUN1 an in the of nuclear and in hALP to are and nuclear The nuclear envelope a for and for nuclear Nuclear envelope and proteins nuclear and with to DNA and in the mammalian is nuclear membrane a mitosis. nuclear envelope and understood that nuclear envelope proteins first to protein the for to not Here, we that hsSUN1 and lamin in with chromosomes in hsSUN1 is the first a protein is that hsSUN1 a in and that to and chromosome de-condensation protein an at the end of chromosomes are to for for the of that DNA to two is in for the of the needs from it is that a DNA with of H3 what DNA de-condensation at the end of is that the to de-condensation is not a at that de-condensation is by in and and of and and of of in histones to histone DNA and to the of a histone which by We hsSUN1 is for the a of histones at the end of and a for the of chromosome de-condensation. from is that chromosome not to for DNA de-condensation. a is to DNA de-condensation of that to three to the hsSUN1 and The first is that hsSUN1 histone histone which and of to and which second is that DNA de-condensation the of a nuclear Here, of hsSUN1 nuclear membrane with de-condensation. in and nuclear nuclear envelope and de-condensation are with is that of the two are in the of a reforming envelope an protein is used to a for of DNA de-condensation. that with and to histone are with a in which and at the of the DNA a is which with in the is nuclear hALP in chromosome by in of the of hALP for chromosome hALP to DNA of hALP DNA and of to DNA de-condensation we the of other are with for hALP and hsSUN1 in DNA de-condensation. is that hsSUN1 with other nuclear nuclear in to hALP. to DNA de-condensation. is is into a to the of for the by histones in chromosome The eukaryotic nucleus is separated from other organelles by an envelope containing two membrane layers continuous with the endoplasmic reticulum. Nuclear membrane proteins fall into three categories according to their localization. The first group is the trans-nuclear membrane proteins resident in the nuclear pore complex (NPC). 2The abbreviations used are:NPCnuclear pore complexSUNSad1-UNC84ChIPchromatin immunoprecipitationINMinner nuclear membraneH3pSer10phosphorylated histone H3 at serine 10hALPhuman acetyl-transferase-like proteinLAPlamin-associated polypeptideLBRlamin B receptorHAThistone acetyltransferaseHDAChistone deacetylaseORFopen reading frameRIPAradioimmune precipitation assay bufferPBSphosphate-buffered salineGSTglutathione S-transferaseHAhemagglutininDAPI4′,6-diamidino-2-phenylindoleGFPgreen fluorescent proteinWTwild type 2The abbreviations used are:NPCnuclear pore complexSUNSad1-UNC84ChIPchromatin immunoprecipitationINMinner nuclear membraneH3pSer10phosphorylated histone H3 at serine 10hALPhuman acetyl-transferase-like proteinLAPlamin-associated polypeptideLBRlamin B receptorHAThistone acetyltransferaseHDAChistone deacetylaseORFopen reading frameRIPAradioimmune precipitation assay bufferPBSphosphate-buffered salineGSTglutathione S-transferaseHAhemagglutininDAPI4′,6-diamidino-2-phenylindoleGFPgreen fluorescent proteinWTwild type The second group contains the inner membrane proteins (INM), which include the lamin B receptor (LBR), emerin, and lamin-associated The group proteins the nuclear membrane nuclear the a the for the of the nucleus and the and the nuclear a which nuclear and in DNA and nuclear pore complex inner nuclear membrane histone H3 at serine acetyl-transferase-like protein lamin-associated lamin B receptor histone acetyltransferase histone reading precipitation assay fluorescent protein type nuclear pore complex inner nuclear membrane histone H3 at serine acetyl-transferase-like protein lamin-associated lamin B receptor histone acetyltransferase histone reading precipitation assay fluorescent protein type proteins are with the nuclear a of in to reading of to chromosome to a of from and and in emerin, lamin and lamin B receptor with is that the proteins are to nuclear and that to the of a of in nuclear membrane to to proteins a at their The first the of of and of proteins that they to at during the at and to function in the of the the other in the nuclear envelope a and a other a to is the function of mammalian proteins the of nuclear membrane at the end of to to chromosome we the for We that hsSUN1 is of the factors to with chromosomes in of hsSUN1 to histones and de-condensation of chromosomes at the end of mitosis. to with mammalian inner nuclear membrane to hsSUN1 and to for chromosome de-condensation. a used by nascently to for in the and hALP from the DNA hsSUN1 from the and into hsSUN1 and and by the by and into hALP by and with for in the protein used for hsSUN1 first with protein and protein to in containing and with and with from the and with and containing the by to and to with of protein and proteins to with in and and the by the assay by the by with by to the and for at The by of and at for with and by and in and and for for and at at for of in in and with for at The with the with in of for to the and in for at and with in for at with in for lamin B nuclear pore complex and to at of to and for at three with and with fluorescent with the with a at in a with hsSUN1 and hALP from with hsSUN1 with hsSUN1 to We with the by and hALP from the DNA hsSUN1 from the and into hsSUN1 and and by the by and into hALP by and with for in the protein used for hsSUN1 first with protein and protein to in containing and with and with from the and with and containing the by to and to with of protein and proteins to with in and and the by the assay by the by with by to the and for at The by of and at for with and by and in and and for for and at at for of in in and with for at The with the with in of for to the and in for at and with in for at with in for lamin B nuclear pore complex and to at of to and for at three with and with fluorescent with the with a at in a with hsSUN1 and hALP from with hsSUN1 with hsSUN1 to We with the by of hsSUN1 to the Nuclear to from to for DNA from DNA and from of not from and that hsSUN1 is in hsSUN1 with a that hsSUN1 three at and and two at and that hsSUN1 is an not which hsSUN1 nuclear DNA we hsSUN1 and in We that hsSUN1 of and a nuclear envelope that hsSUN1 is for nuclear membrane localization. we into hsSUN1 in hsSUN1 of the protein from the nuclear envelope into the of three of with from the the first from hsSUN1 of the protein from the envelope into the the not the to hsSUN1 the hsSUN1 three and first are for in the nuclear Nuclear are not we and to hsSUN1 we first the of hsSUN1 with lamin the nucleus the envelope with lamin and emerin, is at the nuclear hsSUN1 and the nuclear pore complex with which the in are the into lamin and into the with is anaphase, hsSUN1 nascently separated at the of chromosomes the of hsSUN1 and We that hsSUN1 from to of lamin and lamin to and by lamin with hsSUN1 at nuclear other are that hsSUN1 and lamin in to hsSUN1 lamin in chromosomes and proteins with in their with chromosomes We the hsSUN1 with to the of hsSUN1 and we hsSUN1 and and are in hsSUN1 and anaphase, hsSUN1 at the of chromosomes with to chromosome and hsSUN1 with chromosomes to of hsSUN1 and in and first at the of separated by with by DNA with of of and are in are in The of and are assay and are with and by by is that a which other proteins to a nuclear and with chromosomes we a We and and that a are we type hsSUN1 and the hsSUN1 and a precipitation assay a the used in a assay and histone and by a protein containing the hsSUN1 not a in the of for hsSUN1 Nuclear we the for hsSUN1 in nuclear envelope into with a fluorescent protein from and hsSUN1 protein to from the not the to in the nucleus in to and the protein a in and a nuclear envelope in which to of hsSUN1 nuclear envelope and of from with of hsSUN1 and with used a with a and and with is hsSUN1 is and DNA is with and and and used to nuclear envelope we for in for hsSUN1 and at the of DNA in hsSUN1 to in for the of nuclear envelope to and events at the end of and chromosomes Currently, it is two events are the nuclear envelope DNA we chromosome in and hsSUN1 We from chromosomes to DNA and with at the during by and the fluorescent is in hsSUN1 nuclear envelope and in an in DNA of hsSUN1 with with to hsSUN1 and and and DNA with and and of DNA in and by a of to and at the of are of in with of are of and and and in from with by a of in histone histone H3 histone in by a of to the by and at in DNA from a in de-condensation of We in with and a fluorescent histone in the of fluorescent chromosomes in chromosomes in hsSUN1 We of of of in and of of to and to the other with and not of and in to what for chromosome de-condensation in chromosomes are by histones function is by and other events of histone H3 at serine to the other what de-condensation is in and not hsSUN1 and that not in to factors to DNA We histone DNA de-condensation. the of histones in and hsSUN1 by a of for and and with an for and in the other H3 We in and for at and not at of and for at and of that of hsSUN1 not nuclear envelope and chromosome de-condensation and the of and and to that chromosome de-condensation is to a histone acetyltransferase which we that a a nuclear membrane-associated in that the a of is a nuclear membrane-associated protein hALP with hALP with chromosome in a is with hALP a for with we used to hALP B and and in DNA chromosome in with of hALP DNA of hALP with with with DNA with is in of hALP and with of hALP in and by used of of protein by to of in with of are of and and in hALP to from is that chromosomes they by nuclear envelope the of which membrane-associated hALP to DNA which that hsSUN1 hALP to chromosome by a protein with the of hsSUN1 to hALP. is that an and DNA an of an of with hALP contains the hsSUN1 and inner membrane-associated We hALP with into of the three we of in hALP of of de-condensation from and of of DNA of and and hALP function in chromosome de-condensation. of and of with of are from and by from the protein are with hsSUN1 hALP with an by hsSUN1 and we hALP. a we used a of which contains from and that hALP with not of hsSUN1 to the Nuclear to from to for DNA from DNA and from of not from and that hsSUN1 is in hsSUN1 with a that hsSUN1 three at and and two at and that hsSUN1 is an not which hsSUN1 nuclear DNA we hsSUN1 and in We that hsSUN1 of and a nuclear envelope that hsSUN1 is for nuclear membrane localization. we into hsSUN1 in hsSUN1 of the protein from the nuclear envelope into the of three of The with from the the first from hsSUN1 of the protein from the envelope into the the not the to hsSUN1 the hsSUN1 three and first are for in the nuclear Nuclear are not we and to hsSUN1 we first the of hsSUN1 with lamin the nucleus the envelope with lamin and emerin, is at the nuclear hsSUN1 and the nuclear pore complex with which the in are the into lamin and into the with is anaphase, hsSUN1 nascently separated at the of chromosomes the of hsSUN1 and We that hsSUN1 from to of lamin and lamin to and by lamin with hsSUN1 at nuclear other are that hsSUN1 and lamin in to hsSUN1 lamin in chromosomes and proteins with in their with chromosomes We the hsSUN1 with to the of hsSUN1 and we hsSUN1 and and are in hsSUN1 and anaphase, hsSUN1 at the of chromosomes with to chromosome and hsSUN1 with chromosomes is that a which other proteins to a nuclear and with chromosomes we a We and and that a are we type hsSUN1 and the hsSUN1 and a precipitation assay a the used in a assay and histone and by a protein containing the hsSUN1 not a in the of for hsSUN1 Nuclear we the for hsSUN1 in nuclear envelope into with a fluorescent protein from and hsSUN1 protein to from the not the to in the nucleus in to and the protein a in and a nuclear envelope in which to nuclear envelope we for in for hsSUN1 and at the of DNA in hsSUN1 to in for the of nuclear envelope to and events at the end of and chromosomes Currently, it is two events are the nuclear envelope DNA we chromosome in and hsSUN1 We from chromosomes to DNA and with at the during by and the fluorescent is in hsSUN1 nuclear envelope and in an in DNA in DNA from a in de-condensation of We in with and a fluorescent histone in the of fluorescent chromosomes in chromosomes in hsSUN1 We of of of in and of of to and to the other with and not of and in to what for chromosome de-condensation in chromosomes are by histones function is by and other events of histone H3 at serine to the other what de-condensation is in and not hsSUN1 and that not in to factors to DNA We histone DNA de-condensation. the of histones in and hsSUN1 by a of for and and with an for and in the other H3 We in and for at and not at of and for at and of that of hsSUN1 not nuclear envelope and chromosome de-condensation and the of and and hALP to that chromosome de-condensation is to a histone acetyltransferase which we that a a nuclear membrane-associated in that the a of is a nuclear membrane-associated protein We hALP with hALP with chromosome in a is with hALP a for with we used to hALP B and and in DNA chromosome in with hsSUN1 hALP to from is that chromosomes they by nuclear envelope the of which membrane-associated hALP to DNA which that hsSUN1 hALP to chromosome by a protein with the of hsSUN1 to hALP. is that an and DNA de-condensation. We an of an of with hALP contains the hsSUN1 and inner membrane-associated We hALP with into of the three we of in hALP of of de-condensation from and of of DNA of and The from the protein are with hsSUN1 hALP with an by hsSUN1 and we hALP. a we used a of which contains from and that hALP with not for a hsSUN1 is in to other three Here, we that the hsSUN1 three are for nuclear membrane and that is for that hsSUN1 an in the of nuclear and in hALP to are and nuclear The nuclear envelope a for and for nuclear Nuclear envelope and proteins nuclear and with to DNA and in the mammalian is nuclear membrane a mitosis. nuclear envelope and understood that nuclear envelope proteins first to protein the for to not Here, we that hsSUN1 and lamin in with chromosomes in hsSUN1 is the first a protein is that hsSUN1 a in and that to and chromosome de-condensation protein an at the end of chromosomes are to for for the of that DNA to two is in for the of the needs from it is that a DNA with of H3 what DNA de-condensation at the end of is that the to de-condensation is not a at that de-condensation is by in and and of and and of of in histones to histone DNA and to the of a histone which by We hsSUN1 is for the a of histones at the end of and a for the of chromosome de-condensation. from is that chromosome not to for DNA de-condensation. a is to DNA de-condensation of that to three to the hsSUN1 and The first is that hsSUN1 histone histone which and of to and which second is that DNA de-condensation the of a nuclear Here, of hsSUN1 nuclear membrane with de-condensation. in and nuclear nuclear envelope and de-condensation are with is that of the two are in the of a reforming envelope an protein is used to a for of DNA de-condensation. that with and to histone are with a in which and at the of the DNA a is which with in the is nuclear hALP in chromosome by in of the of hALP for chromosome hALP to DNA of hALP DNA and of to DNA de-condensation we the of other are with for hALP and hsSUN1 in DNA de-condensation. is that hsSUN1 with other nuclear nuclear in to hALP. to DNA de-condensation. is is into a to the of for the by histones in chromosome for a hsSUN1 is in to other three Here, we that the hsSUN1 three are for nuclear membrane and that is for that hsSUN1 an in the of nuclear and in hALP to are and nuclear The nuclear envelope a for and for nuclear Nuclear envelope and proteins nuclear and with to DNA and in the mammalian is nuclear membrane a mitosis. nuclear envelope and understood that nuclear envelope proteins first to protein the for to not Here, we that hsSUN1 and lamin in with chromosomes in hsSUN1 is the first a protein is that hsSUN1 a in and that to and chromosome de-condensation protein an at the end of mitosis. chromosomes are to for for the of that DNA to two is in for the of the needs from it is that a DNA with of H3 what DNA de-condensation at the end of is that the to de-condensation is not a at that de-condensation is by in and and of and and of of in histones to histone DNA and to the of a histone which by We hsSUN1 is for the a of histones at the end of and a for the of chromosome de-condensation. from is that chromosome not to for DNA de-condensation. a is to DNA de-condensation of that to three to the hsSUN1 and The first is that hsSUN1 histone histone which and of to and which second is that DNA de-condensation the of a nuclear Here, of hsSUN1 nuclear membrane with de-condensation. in and nuclear nuclear envelope and de-condensation are with is that of the two are in the of a reforming envelope an protein is used to a for of DNA de-condensation. that with and to histone are with a in which and at the of the DNA a is which with in the is nuclear hALP in chromosome by in of the of hALP for chromosome hALP to DNA of hALP DNA and of to DNA de-condensation we the of other are with for hALP and hsSUN1 in DNA de-condensation. is that hsSUN1 with other nuclear nuclear in to hALP. to DNA de-condensation. is is into a to the of for the by histones in chromosome We DNA for hsSUN1 and at of for for and for and and of the for reading of the with with
Chi et al. (Fri,) studied this question.