Human folliculin delays cell cycle progression through late S and G2/M-phases: effect of phosphorylation and tumor associated mutations

master's thesis

• Title (croatian): Ljudski folikulin odgađa napredovanje staničnog ciklusa putem kasne S i G2/M faze: učinak fosforilacije i mutacija povezanih s tumorom
• Author: Damien Jonas Adolphus Wilson
• Mentor: Maja Vlahović (mentor)
• Committee member: Floriana Jakuš (predsjednik povjerenstva)
• Committee member: Ljiljana Šerman (član povjerenstva)
• Committee member: Maja Vlahović (član povjerenstva)
• Granter: University of Zagreb; School of Medicine; (Department of Medical Biology); Zagreb
• Defense date and country: 2018-07-13, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Clinical Medical Sciences; Medical Microbiology

Abstract

The Birt-Hogg-Dube disease occurs as a result of germline mutations in the human Folliculin gene (FLCN), and is characterized by clinical features including fibrofolliculomas, lung cysts and multifocal renal neoplasia. Clinical and genetic evidence suggest that FLCN acts as a tumor suppressor gene. The human cell line UOK257, derived from the renal cell carcinoma of a patient with a germline mutation in the FLCN gene, harbors a truncated version of the FLCN protein. Reconstitution of the wild type FLCN protein into UOK257 cells delays cell cycle progression, due to a slower progression through the late S and G2/M-phases. Similarly, Flcn–/– mouse embryonic fibroblasts progress more rapidly through the cell cycle than wild type controls (Flcnflox/flox). The reintroduction of tumor-associated FLCN mutants (FLCN DF157, FLCN 1–469 or FLCN K508R) fails to delay cell cycle progression in UOK257 cells. Additionally, FLCN phosphorylation (on Serines 62 and 73) fluctuates throughout the cell cycle and peaks during the G2/M phase in cells treated with nocodazole. In keeping with this observation, the reintroduction of a FLCN phosphomimetic mutant into the UOK257 cell line results in faster progression through the cell cycle compared to those expressing the wild type FLCN protein. These findings suggest that the tumor suppression function of FLCN may be linked to its impact on the cell cycle and that FLCN phosphorylation is important for this activity. Additionally, these observations describe a novel in vitro assay for testing the functional significance of FLCN mutations and/or genetic polymorphisms.

Abstract (croatian)

Birt-Hogg-Dubeova bolest razvija se kao rezultat zametnih mutacija u ljudskom genu za folikulin (FLCN), a karakteriziraju je kliničke promjene poput razvoja fibrofolikuloma, plućnih cisti i multifokalne neoplazije bubrega. Dosadašnji klinički i genetički dokazi ukazuju na to da FLCN djeluje kao tumor-supresorski gen. Ljudska stanična kultura UOK257, dobivena od pacijenta s karcinomom bubrežnih stanica s pratećom zametnom mutacijom gena FLCN, specifična je zbog postojanja skraćene verzije bjelančevine FLCN. Rekonstitucija divljeg tipa bjelančevine FLCN u UOK257 stanice odgađa napredovanje staničnog ciklusa kroz kasnu S i G2/M fazu. Na sličan način Flcn-/- mišji embrijski fibroblasti napreduju znatno brže kroz stanični ciklus u usporedbi s kontrolnim divljim tipovima (Flcnflox/flox). Reintrodukcija mutiranih oblika gena FLCN (FLCN ΔF157, FLCN 1-469 or FLCN K508R) ne uspjeva odgoditi napredovanje staničnog ciklusa u UOK257 stanicama. Nadalje, fosforilacija FLCN-a (na serinu 62 i 73) fluktuira tijekom staničnog ciklusa, a vršnu vrijednost postiže tijekom G2/M faze u stanicama tretiranim nokodazolom. U skladu s navedenim opažanjem, ponovni unos fosfomimetičkog FLCN mutanta u UOK257 stanice rezultira bržim napredovanjem kroz stanični ciklus u usporedbi sa staničnom linijom koja nosi divlji tip bjelančevine FLCN. Ovi rezultati ukazuju na to da bi tumor-supresorska funkcija FLCN-a mogla biti povezana s njegovim učinkom na stanični ciklus, ali i da je fosforilacija FLCN-a jedan od ključnih koraka za tu aktivnost. Osim toga, ova zapažanja opisuju sasvim novi in vitro model za testiranje funkcionalne značajnosti mutacija gena FLCN i/ili genetskih
polimorfizama.

• Keywords: Birt-Hogg-Dube disease; folliculin; tumor suppressor gene; cell cycle
• Keywords (croatian): Birt-Hogg-Dubeova bolest; folikulin; tumor-supresorski gen; stanični ciklus
• Language: english
• URN:NBN: urn:nbn:hr:105:244521
• Study programme: Title: Medicine (in English language); Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: doktor/doktorica medicine (doktor/doktorica medicine)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2019-04-26 12:16:01