Functional characterization of the mitotic kinesin like protein Mklp2 [Elektronische Ressource] / Stefan Hümmer. Betreuer: Erich Nigg

Stefan Hümmer

Sujets

• Biologie

Informations

• Publié par: ludwig-maximilians-universitat_munchen
• Publié le: 01 janvier 2009
• Nombre de lectures: 102
• Langue: Deutsch
• Poids de l'ouvrage: 2 Mo

Extrait

Functional characterization of the
mitotic kinesin-like protein Mklp2









Dissertation
zur Erlangung des Doktorgrades der Naturwissenschaften
(Dr. rer. nat.)
der Fakultät für Biologie der Ludwig-Maximilians-Universität
München



vorgelegt von

Stefan Hümmer



Martinsried / München 2009






























Erstgutachter: Prof. Dr. Erich A. Nigg
Zweitgutachter: Prof. Dr. Heinrich Leonhardt

Tag der mündlichen Prüfung: 14.12.2009 Ehrenwörtliche Erklärung über frühere Promotionsversuche


Hiermit erkläre ich, dass ich, Stefan Hümmer, die vorliegende Dissertation selbständig und
ohne unerlaubte Hilfe angefertigt habe. Sämtliche Experimente sind von mir selbst
durchgeführt, ausser wenn explizit auf Dritte verwiesen wird. Ich habe weder anderweitig
versucht, eine Dissertation einzureichen oder eine Doktorprüfung durchzuführen, noch habe
ich diese Dissertation oder Teile derselben einer anderen Prüfungskommission vorgelegt.


München, den 13.12.2009
Table of Contents

Table of Contents

Acknowledgements.................................................................................................... 1
Zusammenfassung..................................................................................................... 3
Summary ..................................................................................................................... 5
Introduction................................................................................................................. 6
1 The cell cycle and cell division ......................................................................................6
2 M-phase............................................................................................................................7
2.1 The mitotic spindle.............................................7
2.2 Regulation of mitotic progression by Cdk1.................................................................8
3 Cytokinesis ...........................................................10
3.1 Assembly and ingression of the contractile ring .......................................................11
3.2 Assembly of the spindle midzone........................................................12
3.3 Regulation of cytokinesis in space and time.............................................................14
4 The chromosomal passenger complex (CPC)......................16
5 Kinesins and the kinesin-6 family................................................................................19
6 The intermediate filament (IF) vimentin .................................................22
7 Chemical genetics................................................23
Aim of this work........................................................................................................ 26
Results....................................................................................................................... 27
Results 1: Regulation of the Mklp2.................................................................................27
1.1 Binding of Mklp2 to MTs after anaphase onset depends on its active motor domain
..............................................................................27
1.2 Mklp2 and the CPC are mutually dependent on each other for midzone localization......................28
1.3 The phospho-mimic mutant of INCENP (T59E) does not complement the function of
the CPC in cytokinesis....................................................................................................29
1.4 The phospho-mimic E) can not restore the localization of
Mklp2 at the central spindle...................................32
1.5 Mklp2 and the CPC interact upon anaphase onset..................................................33
1.6 The interaction between the CPC and Mklp2 is negatively regulated by Cdk1 ........34
1.7 Binding of the CPC and Mklp2 to MTs is negatively regulated by Cdk1 ..................35
1.8 INCENP is required to localize Mklp2 close to the ends of stable MTs in cells with
low Cdk1 activity.............................................................................................................37
1.9 Aurora B activity is required for the correct localization of the Mklp2/CPC complex in
cells undergoing monopolar cytokinesis.........................................................................39
Conclusion 1............................................................40
I Table of Contents

Results 2: The function of Mklp2 in late cytokinesis ....................................................41
2.1 Mklp2 depletion by RNAi causes a failure in late cytokinesis...................................41
2.2 Delocalization of vimentin to the cytokinetic bridge in Mklp2-depleted cells ............42
2.3 The phospho-mimic mutant of INCENP (T59E) can not restore the correct
localization of vimentin at the central spindle .................................................................44
2.4 No cytokinesis defect upon Mklp2 depletion in vimentin negative MCF-7 cells .......46
Conclusion 2.....................................................................................................................48
Results 3: Novel inhibitors for mitotic kinesins ............................................................49
3.1 Screen for novel Eg5 inhibitors..49
3.2 Improvement of monastrol by an applied structure activity relation (SAR) method..50
3.3 Novel inhibitors for kinesins in cytokinesis ...............................................................53
3.4 SH compounds inhibit Mklp2 and MPP1 in vitro and induce a cytokinesis defect in
vivo .................................................................................................................................54
3.5 SH1 does not interfere with Mklp2/MPP1 independent cellular processes ..............55
3.6 Binding of SH compounds to the target proteins is mediated by a kinesin 6-family
specific insertion in the motor domain....................58
3.7 The expression profile and RNAi phenotype of MPP1 do not correlate with a
potential target of SH compounds in vivo.......................................................................60
3.8 SH2 treatment correlates with the RNAi phenotype of Mklp2 in HeLa and MCF-7
cells ................................................................................................................................61
3.9 SH treatment does not interfere with the localisation of the target proteins in vivo ..62
Conclusion 3.....................................................................................................................64
Discussion................................................................................................................. 65
1 Cdk1 negatively regulates midzone localization of Mklp2 and the CPC..................65
1.1 MT binding of Mklp2 at anaphase onset is mediated by its motor domain...............65
1.2 Mklp2 and the CPC are mutually dependent on each other for midzone localization
.......................................................................................................................................65
1.3 The phospho-mimicking mutant of INCENP (T59E) as a tool to uncouple the early
from the late functions of the CPC in mitosis..................................................................66
1.4 The interaction between the CPC and Mklp2 is negatively regulated by Cdk1 ........67
1.5 Binding of the CPC and Mklp2 to MTs is negatively regulated by Cdk1 ..................68
1.6 INCENP is required to localize Mklp2 close to the ends of stable MTs in the absence
of Cdk1 activity ...............................................................................................................68
1.7 A potential feedback loop mechanism for the localization of Mklp2 and the CPC to
the spindle midzone...............................................69
1.8 The role of stable MTs in cleavage furrow positioning .............................................71
2 The function of Mklp2 in late cytokinesis ...................................................................74
3 Small molecule inhibitors for cytokinetic kinesins....................................................77
II Table of Contents

Materials and Methods............................................................................................. 80
1 Chemicals and buffers..................................................................................................80
2 Cloning procedures ........................80
3 Purification of His-fusion proteins from E. coli..........................................................82
4 Purification of tubulin and generation of stabilized MTs...........................................83
4.1 Purification of tubulin from pig brains ...................................................................