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Regulation and dynamics of the nucleoplasmic pool of A-type lamins

Konstantina Georgiou

Art der Arbeit

Masterarbeit

Universität

Universität Wien

Fakultät

Zentrum für Molekulare Biologie

Studiumsbezeichnung bzw. Universitätlehrgang (ULG)

Masterstudium Molekulare Biologie

Betreuer*in

Roland Foisner

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DOI

10.25365/thesis.54242

URN

urn:nbn:at:at-ubw:1-14022.43121.579067-2

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(Print-Exemplar eventuell in Bibliothek verfügbar)

Abstracts

Abstract

(Deutsch)

Nicht angegeben.

Abstract

(Englisch)

The nuclear lamina is a filamentous meshwork opposing the inner nuclear membrane of metazoan cells. It provides mechanical support to the nucleus and is involved in a plethora of cellular activities, such as nuclear mechanosignaling and chromatin organization. A- and B- type lamins are the major components of the lamina. B-type lamins remain permanently farnesylated and membrane-associated, while A-type lamins, due to additional post-translational processing and removal of the farnesyl residue, can also be found as a more soluble and dynamic pool in the nucleoplasm. The emerging unique functions of intranuclear lamins prompted us to address remaining open questions regarding their regulation and dynamics during the cell cycle. First, we investigated the origin and dynamics of nucleoplasmic A-type lamins using ectopically expressed EGFP-pre-lamin A and live-cell imaging. By analyzing changes in the distribution of newly synthesized wild type pre-lamin A and an assembly-deficient lamin A- ΔΚ32 mutant, both presumable farnesylated, we show that newly expressed farnesylated constructs are rapidly recruited to the nuclear periphery initially, even when they are unable to assemble into the lamina, before they partially, or completely, in the case of mutant lamin A, translocate to the nucleoplasm. In contrast, the fully processed lamin variants lacking farnesylation are localized exclusively in the nucleoplasm in early G1-phase following post-mitotic nuclear reassembly and, unlike the assembly-deficient lamin A- ΔΚ32 mutant, the majority of wildtype lamin A translocates to the nuclear periphery throughout G1. These data show that both transient lamin A farnesylation and its assembly into the lamina contribute to peripheral localization of lamin A, but these events take place at different cell cycle stages and depend on the processing state of lamins. Secondly, we investigated the role of the nucleoplasmic lamin A/C-binding protein, lamin associated polypeptide 2 alpha (LAP2α), in the regulation of lamin A localization. Direct monitoring of ectopic EGFP-tagged lamin A throughout G1, and endogenously tagged mEos3.2-lamin A/C in G1, S and G2 phase in LAP2α wildtype and knockout cells revealed no changes in the distribution of intranuclear lamins in the absence of LAP2α. However, we find that antibody staining of nucleoplasmic A-type lamins as well as their solubility and mobility is significantly reduced in LAP2α-depleted cells. Based on these data, we propose a revised model of LAP2α-mediated regulation of the nucleoplasmic lamin A/C pool. We suggest that LAP2α does not influence the level of nucleoplasmic lamins, but rather maintains them in a soluble and dynamic pool, possibly by affecting the assembly state of intranuclear lamins.

Autor*innen

Konstantina Georgiou

Haupttitel (Englisch)

Regulation and dynamics of the nucleoplasmic pool of A-type lamins

Publikationsjahr

2018

Umfangsangabe

77 Seiten : Illustrationen, Diagramme

Sprache

Englisch

Beurteiler*in

Roland Foisner

Klassifikation

42 Biologie > 42.13 Molekularbiologie

AC Nummer

AC15187348

Utheses ID

47929

Studienkennzahl

UA | 066 | 834 | |

Detailansicht

Abstracts

Schlagwörter