ULOGA PROTEINA IQGC U REGULACIJI STANIČNE ADHEZIJE U PROTISTU DICTYOSTELIUM DISCOIDEUM

doctoral thesis

• Title (english): THE ROLE OF IQGC PROTEIN IN THE REGULATION OF ADHESION IN DICTYOSTELIUM DISCOIDEUM PROTIST
• Author: Lucija Mijanović
• Mentor: Igor Weber (mentor)
• Committee member: Biljana Balen (predsjednik povjerenstva)
• Committee member: Inga Urlić (član povjerenstva)
• Committee member: Vedrana Filić Mileta (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2023-03-24, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology
• Universal decimal classification (UDC): 577 - Biochemistry. Molecular biology. Biophysics

Abstract

Protein IqgC iz protista Dictyostelium discoideum dijeli svojstva proteina iz skupina IQGAP i
RasGAP te regulira endocitozu deaktivacijom male GTPaze RasG. Cilj ovog rada je
karakterizacija dodatne uloge proteina IqgC u regulaciji stanične adhezije. Testovima adhezije
pokazala sam da stanice mutanta iqgCimaju defekt u pričvršćivanju za podlogu. Ekspresijom
skraćenih varijanti proteina IqgC u stanicama iqgCutvrdila sam da je za normalnu adheziju
nužna prisutnost obje domene proteina, domene RGCt i domene GAP. Korištenjem
mikroskopije TIRF ustanovila sam da je protein IqgC lokaliziran u fokalnim adhezijskim
strukturama, gdje ga navodi domena RGCt. Biokemijskim pokusima i metodom BiFC
ustanovila sam da protein IqgC veže malu GTPazu RapA. Analizom kretanja stanica otkrila
sam anomalije u nasumičnom kretanju i kemotaksiji stanica mutanta iqgC-
, vjerojatno
posredovane deregulacijom aktivnosti GTPaza RasG i RapA. Analizom lokalizacije i
aktivnosti proteina IqgC u staničnim sojevima deficijentnim za razne proteine regulatore
adhezije identificirala sam signalni put reguliran proteinom RapA unutar kojeg protein IqgC
djeluje kao pozitivni regulator adhezije.

Abstract (english)

IqgC protein from the protist Dictyostelium discoideum shares the properties of IQGAP and
RasGAP proteins and regulates endocytosis by deactivating small GTPase RasG. The goal of
this work is an investigation of an additional role of IqgC in the regulation of adhesion. Using
adhesion assays, I showed that mutant iqgCcells attach poorly to the substratum. Rescue
experiments with truncated variants of IqgC showed that both RGCt and GAP domains are
necessary for normal adhesion. Using TIRF microscopy, I established that IqgC is localized in
focal adhesion structures and that the RGCt domain is responsible for its proper localization.
Biochemistry and BiFC experiments identified an interaction between IqgC and RapA.
Migration assays detected anomalies in random motility and chemotaxis of iqgCcells, likely
mediated by deregulation of RasG and RapA signaling. By testing the localization and
activity of the IqgC protein in cell strains deficient for various adhesion regulators, I
identified a signaling pathway regulated by RapA where IqgC acts as a positive regulator of
cell adhesion.

• Keywords: adhezija; IqgC; RapA; RasG; GTPaze Ras; Dictyostelium discoideum
• Keywords (english): adhesion; IqgC; RapA; RasG; Ras GTPases; Dictyostelium discoideum
• Language: croatian
• URN:NBN: urn:nbn:hr:217:565685
• Promotion: 2023
• Study programme: Title: Biology; Study programme type: university; Study level: postgraduate; Academic / professional title: doktor/doktorica znanosti, područje prirodnih znanosti, polje biologija (doktor/doktorica znanosti, područje prirodnih znanosti, polje biologija)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Embargoed access; Embargo expiration date: 2025-03-24
• Created on: 2023-04-03 09:25:54