Hp1α is a chromatin crosslinker that controls nuclear and mitotic chromosome mechanics

Amy R. Strom; Ronald J. Biggs; Edward J. Banigan; Xiaotao Wang; Katherine Chiu; Cameron Herman; Jimena Collado; Feng Yue; Joan C.Ritland Politz; Leah J. Tait; David Scalzo; Agnes Telling; Mark Groudine; Clifford P. Brangwynne; John F. Marko; Andrew D. Stephens

doi:10.7554/eLife.63972

Hp1α is a chromatin crosslinker that controls nuclear and mitotic chromosome mechanics

Amy R. Strom, Ronald J. Biggs, Edward J. Banigan, Xiaotao Wang, Katherine Chiu, Cameron Herman, Jimena Collado, Feng Yue, Joan C.Ritland Politz, Leah J. Tait, David Scalzo, Agnes Telling, Mark Groudine, Clifford P. Brangwynne, John F. Marko, Andrew D. Stephens^*

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

61 Scopus citations

Abstract

Chromatin, which consists of DNA and associated proteins, contains genetic information and is a mechanical component of the nucleus. Heterochromatic histone methylation controls nucleus and chromosome stiffness, but the contribution of heterochromatin protein HP1α (CBX5) is unknown. We used a novel HP1α auxin-inducible degron human cell line to rapidly degrade HP1α. Degradation did not alter transcription, local chromatin compaction, or histone methylation, but did decrease chromatin stiffness. Single-nucleus micromanipulation reveals that HP1α is essential to chromatin-based mechanics and maintains nuclear morphology, separate from histone methylation. Further experiments with dimerization-deficient HP1α^I165E indicate that chromatin crosslinking via HP1α dimerization is critical, while polymer simulations demonstrate the importance of chromatin-chromatin crosslinkers in mechanics. In mitotic chromosomes, HP1α similarly bolsters stiffness while aiding in mitotic alignment and faithful segregation. HP1α is therefore a critical chromatin-crosslinking protein that provides mechanical strength to chromosomes and the nucleus throughout the cell cycle and supports cellular functions.

Original language	English (US)
Article number	e63972
Journal	eLife
Volume	10
DOIs	https://doi.org/10.7554/eLife.63972
State	Published - Jun 2021

Funding

This work was supported by the NIH Center for 3D Structure and Physics of the Genome of the 4DN Consortium (U54DK107980 and 1UM1HG011536) and the NIH Physical Sciences-Oncology Center (U54CA193419). CPB and ARS were supported by the Howard Hughes Medical Institute, and grants from the NIH 4D Nucleome Program (U01 DA040601); ARS is supported by the LSRF Fellowship from Mark Foundation For Cancer Research. We thank Daniel S.W. Lee for experimental discussion and support, and Yiche Chang for the generous gift of pHR-HP1α-mCherry plasmids. We thank Daniel Shams for helping write a custom script for analyzing mitotic chromosome micromanipulation force measurements. EJB was supported by the NIH Center for 3D Structure and Physics of the Genome of the 4DN Consortium (U54DK107980), the NIH Physical Sciences-Oncology Center (U54CA193419), and NIH grant GM114190. XW and FY are supported by 1R35GM124820, R01HG009906, U01CA200060 and R24DK106766. JP, DS, LT, AT, and MG were funded by 4DN (U01DA040583). KC and ADS are supported by the Pathway to Independence Award (R00GM123195) and 4D Nucleome two center grant (1UM1HG011536). This work was supported by the NIH Center for 3D Structure and Physics of the Genome of the 4DN Consortium (U54DK107980 and 1UM1HG011536) and the NIH Physical Sciences-Oncology Center (U54CA193419). CPB and ARS were supported by the Howard Hughes Medical Institute, and grants from the NIH 4D Nucleome Program (U01 DA040601); ARS is supported by the LSRF Fellowship from Mark Foundation For Cancer Research. We thank Daniel S.W. Lee for experimental discussion and support, and Yiche Chang for the generous gift of pHR-HP1a-mCherry plasmids. We thank Daniel Shams for helping write a custom script for analyzing mitotic chromosome micromanipulation force measurements. EJB was supported by the NIH Center for 3D Structure and Physics of the Genome of the 4DN Consortium (U54DK107980), the NIH Physical Sciences-Oncology Center (U54CA193419), and NIH grant GM114190. XW and FY are supported by 1R35GM124820, R01HG009906, U01CA200060 and R24DK106766. JP, DS, LT, AT, and MG were funded by 4DN (U01DA040583). KC and ADS are supported by the Pathway to Independence Award (R00GM123195) and 4D Nucleome two center grant (1UM1HG011536).

ASJC Scopus subject areas

General Immunology and Microbiology
General Biochemistry, Genetics and Molecular Biology
General Neuroscience

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Strom, A. R., Biggs, R. J., Banigan, E. J., Wang, X., Chiu, K., Herman, C., Collado, J., Yue, F., Politz, J. C. R., Tait, L. J., Scalzo, D., Telling, A., Groudine, M., Brangwynne, C. P., Marko, J. F., & Stephens, A. D. (2021). Hp1α is a chromatin crosslinker that controls nuclear and mitotic chromosome mechanics. eLife, 10, Article e63972. https://doi.org/10.7554/eLife.63972

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title = "Hp1α is a chromatin crosslinker that controls nuclear and mitotic chromosome mechanics",

abstract = "Chromatin, which consists of DNA and associated proteins, contains genetic information and is a mechanical component of the nucleus. Heterochromatic histone methylation controls nucleus and chromosome stiffness, but the contribution of heterochromatin protein HP1α (CBX5) is unknown. We used a novel HP1α auxin-inducible degron human cell line to rapidly degrade HP1α. Degradation did not alter transcription, local chromatin compaction, or histone methylation, but did decrease chromatin stiffness. Single-nucleus micromanipulation reveals that HP1α is essential to chromatin-based mechanics and maintains nuclear morphology, separate from histone methylation. Further experiments with dimerization-deficient HP1αI165E indicate that chromatin crosslinking via HP1α dimerization is critical, while polymer simulations demonstrate the importance of chromatin-chromatin crosslinkers in mechanics. In mitotic chromosomes, HP1α similarly bolsters stiffness while aiding in mitotic alignment and faithful segregation. HP1α is therefore a critical chromatin-crosslinking protein that provides mechanical strength to chromosomes and the nucleus throughout the cell cycle and supports cellular functions.",

author = "Strom, {Amy R.} and Biggs, {Ronald J.} and Banigan, {Edward J.} and Xiaotao Wang and Katherine Chiu and Cameron Herman and Jimena Collado and Feng Yue and Politz, {Joan C.Ritland} and Tait, {Leah J.} and David Scalzo and Agnes Telling and Mark Groudine and Brangwynne, {Clifford P.} and Marko, {John F.} and Stephens, {Andrew D.}",

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AU - Strom, Amy R.

AU - Biggs, Ronald J.

AU - Banigan, Edward J.

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AU - Chiu, Katherine

AU - Herman, Cameron

AU - Collado, Jimena

AU - Yue, Feng

AU - Politz, Joan C.Ritland

AU - Tait, Leah J.

AU - Scalzo, David

AU - Telling, Agnes

AU - Groudine, Mark

AU - Brangwynne, Clifford P.

AU - Marko, John F.

AU - Stephens, Andrew D.

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N2 - Chromatin, which consists of DNA and associated proteins, contains genetic information and is a mechanical component of the nucleus. Heterochromatic histone methylation controls nucleus and chromosome stiffness, but the contribution of heterochromatin protein HP1α (CBX5) is unknown. We used a novel HP1α auxin-inducible degron human cell line to rapidly degrade HP1α. Degradation did not alter transcription, local chromatin compaction, or histone methylation, but did decrease chromatin stiffness. Single-nucleus micromanipulation reveals that HP1α is essential to chromatin-based mechanics and maintains nuclear morphology, separate from histone methylation. Further experiments with dimerization-deficient HP1αI165E indicate that chromatin crosslinking via HP1α dimerization is critical, while polymer simulations demonstrate the importance of chromatin-chromatin crosslinkers in mechanics. In mitotic chromosomes, HP1α similarly bolsters stiffness while aiding in mitotic alignment and faithful segregation. HP1α is therefore a critical chromatin-crosslinking protein that provides mechanical strength to chromosomes and the nucleus throughout the cell cycle and supports cellular functions.

AB - Chromatin, which consists of DNA and associated proteins, contains genetic information and is a mechanical component of the nucleus. Heterochromatic histone methylation controls nucleus and chromosome stiffness, but the contribution of heterochromatin protein HP1α (CBX5) is unknown. We used a novel HP1α auxin-inducible degron human cell line to rapidly degrade HP1α. Degradation did not alter transcription, local chromatin compaction, or histone methylation, but did decrease chromatin stiffness. Single-nucleus micromanipulation reveals that HP1α is essential to chromatin-based mechanics and maintains nuclear morphology, separate from histone methylation. Further experiments with dimerization-deficient HP1αI165E indicate that chromatin crosslinking via HP1α dimerization is critical, while polymer simulations demonstrate the importance of chromatin-chromatin crosslinkers in mechanics. In mitotic chromosomes, HP1α similarly bolsters stiffness while aiding in mitotic alignment and faithful segregation. HP1α is therefore a critical chromatin-crosslinking protein that provides mechanical strength to chromosomes and the nucleus throughout the cell cycle and supports cellular functions.

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Hp1α is a chromatin crosslinker that controls nuclear and mitotic chromosome mechanics

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