Giordano, Lucia Laura (2015) Molecular mechanisms of the CtBP1-S/BARS dependent membrane fission processes involved in membrane trafficking and in mitosis. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Resource language: English
Title: Molecular mechanisms of the CtBP1-S/BARS dependent membrane fission processes involved in membrane trafficking and in mitosis.
Giordano, Lucia
Date: 27 March 2015
Number of Pages: 170
Institution: Università degli Studi di Napoli Federico II
Department: Scienze Chimiche
Scuola di dottorato: Biotecnologie
Dottorato: Scienze biotecnologiche
Ciclo di dottorato: 27
Coordinatore del Corso di dottorato:
Sannia, GiovanniUNSPECIFIED
Date: 27 March 2015
Number of Pages: 170
Keywords: Membrane fission, membrane trafficking, mitosis, CtBP1-S/BARS
Settori scientifico-disciplinari del MIUR: Area 05 - Scienze biologiche > BIO/10 - Biochimica
Area 05 - Scienze biologiche > BIO/11 - Biologia molecolare
Date Deposited: 07 Apr 2015 07:44
Last Modified: 17 Apr 2018 01:00
DOI: 10.6093/UNINA/FEDOA/10150

Collection description

This thesis is focused on the role of CtBP1-S/BARS (C-terminal binding protein 1-short form/ brefeldin A ADP-ribosylation substrate; BARS), in membrane fission, a process that is involved in both intracellular membrane trafficking and Golgi partitioning during mitosis. The Golgi complex is the organelle that was initially described in 1898 by the Italian Camillo Golgi, although the real existence of this organelle was debated for decades, until the introduction of electron microscopy in the 1950s, which solved the controversy. Nowadays, it is well known that the Golgi complex is a cell organelle that is involved in many cellular functions, such as intracellular trafficking, post-translational modification of proteins and lipids, cell partitioning during mitosis, and membrane curvature and fission. Golgi membrane curvature and the membrane fission that follows is integral to many cell functions, such as membrane trafficking and cell partitioning. They are required for the formation of intracellular transport carriers, and are controlled by cooperative contributions of both lipids and proteins. Membrane fission appears to rely on multiple mechanisms, and many of these are mediated by BARS. BARS is a dual-function protein that acts as a co-repressor of transcription in the nucleus and as a regulator of membrane fission in the cytoplasm. In our laboratory, it has been demonstrated that BARS is required in the following processes: macropinocytosis, fluid-phase endocytosis, membrane transport from the trans-Golgi network (TGN) to the basolateral plasma membrane (PM), COPI vesicle formation, and Golgi partitioning that occurs during the G2 phase of the cell cycle (a step that controls cell entry into mitosis). In the first part of my project, I focused my studies on the fission-inducing property of BARS that is required during the formation of basolaterally directed post-Golgi carriers. Here, the fission-driving property of BARS is associated with a lysophosphatidic acid acyltransferase (LPAAT) activity. I have shown that BARS specifically binds LPAATδ, a Golgi-resident enzyme that our laboratory has characterised as an LPAAT enzyme that can incorporate acyl-coenzyme A (acylCoA) into lysophosphatidic acid (LPA), to form phosphatidic acid (PA). This LPAATδ activity is required at the fission step during post-Golgi carrier formation, as shown by long tubular carrier precursors that emanate from the Golgi mass but cannot undergo fission under LPAATδ inhibition. In the second part of my project, I focused on the fission-inducing property of BARS in Golgi partitioning during mitosis. Mitosis, or cell division, requires accurate duplication and segregation of the cell contents, which includes not only the genome, but also the intracellular organelles. Correct inheritance of the Golgi complex is crucial for cell division. The Golgi complex is composed of individual stacks of cisternae that are laterally connected by tubules, and the cleavage of these tubules in G2 phase leads to the break-up of the Golgi ribbon into separate stacks. Treatments that block the fission-inducing activity of BARS inhibit the cleavage of these tubules, which results in potent and prolonged cell-cycle block in G2 phase. With the aim to better understand and define the molecular mechanisms underlying this BARS-mediated Golgi-ribbon unlinking process, I analysed: (i) the role of the LPAATδ enzyme, a BARS interactor, in this process; and (ii) whether the BARS-driven fission machinery interface with the other well-known signalling pathways is required for Golgi fragmentation in mitosis.


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