Calcium-induced nuclear actin and FAM110A-regulated spindle actin ensure the genomic integrity of interphase and mitotic cells

Abstract: Nuclear actin is involved in the regulation of transcription, DNA repair, and chromatin dynamics and is triggered by a variety of factors such as DNA damage, cell spreading, viral infection, and calcium signaling. In this study, we optimized a method of measuring nuclear calcium transients and investigated the kinetics and mechanisms of calcium signaling-induced nuclear actin filaments by utilizing the calmodulin-based calcium sensor jGCaMP7f and a nanobody-based actin chromobody. We found that the calcium sensor jGCaMP7f-NLS demonstrates a broader dynamic range than previous calcium sensors. We showed that nuclear calcium transients precede nuclear actin assembly by a few seconds and further established that polymerization of nuclear actin filaments occurs independently of the Arp2/3 function.
In contrast to calcium-mediated nuclear actin, we had previously shown that spindle actin, an aster-shaped actin structure that appears around centrosomes at the onset of mitosis, requires the activity of the Arp2/3 complex. In this thesis, we characterized how spindle actin filaments are guiding kinetochore microtubules following nuclear envelope breakdown. We further investigated the mechanism through which the interplay of spindle actin and microtubules control mitotic fidelity by screening three actin-microtubule crosslinkers: SEPT7, CLASP2, and FAM110A. We found a centrosomal localization of all three candidates in high resolution microscopy. We show that FAM110A, but not SEPT7 and CLASP2 control the organization of spindle actin and guidance of microtubules by actin. Through immunoprecipitation and in vitro reconstitution assays we found that the interaction of FAM110A with actin is mediated by its N-terminus (a.a. 40-61), whereas its interaction with microtubules is mediated by its C-terminus (a.a. 188-221). Moreover, we demonstrate that the interaction of FAM110A with actin is important for the maintenance of genomic integrity prior to the transition to anaphase, which is controlled by the spindle assembly checkpoint. We provide evidence that phosphorylation of FAM110A by cyclin kinase 1 (CK1) is necessary for the interaction of FAM110A and actin, thus for mitotic fidelity

Angaben zum Objekt

• Standort: Deutsche Nationalbibliothek Frankfurt am Main
• Umfang: Online-Ressource
• Sprache: Englisch
• Anmerkungen: Universität Freiburg, Dissertation, 2024

Klassifikation und Themen

• Schlagwort: Actin-bindende Proteine ; Zellskelett ; Actin ; Actin-Filament ; Struktur-Aktivitäts-Beziehung ; Kernhülle

Beteiligte, Orts- und Zeitangaben

• Ereignis: Veröffentlichung
• (wo): Freiburg
• (wer): Universität
• (wann): 2024
• Urheber: Safaralizade, Mahira
• Beteiligte Personen und Organisationen: Grosse, Robert ; Albert-Ludwigs-Universität Freiburg. Fakultät für Biologie

Weitere Informationen

• DOI: 10.6094/UNIFR/255187
• URN: urn:nbn:de:bsz:25-freidok-2551878
• Rechteinformation: Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Letzte Aktualisierung: 25.03.2025, 13:55 MEZ