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dc.contributor.authorPapanicolaou, Kyriakosen_US
dc.date.accessioned2015-08-07T03:21:19Z
dc.date.available2015-08-07T03:21:19Z
dc.date.issued2013
dc.date.submitted2013
dc.identifier.other(ALMA)contemp
dc.identifier.urihttps://hdl.handle.net/2144/12827
dc.descriptionThesis (Ph.D.)--Boston University PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you.en_US
dc.description.abstractMitofusin-1 (Mfn-1) and mitofusin-2 (Mfn-2) are membrane-embedded mechanoenzymes involved in the remodelling and merging of the mitochondrial biomembrane. In differentiated cardiac myocytes, mitochondria occupy a third of the cell's volume and express both Mfn-1 and Mfn-2. The present thesis was aimed at exploring the roles of Mfn-1 and Mfn-2 specifically in cardiac myocytes using loss-offunction approaches in mice. We individually ablated either Mfn-1 or Mfn-2 specifically in cardiac myocytes. Ultramicroscopic analysis conducted in hearts of Mfn-1 KO or Mfn-2 KO mice revealed significant alterations in mitochondrial structure. Nevertheless, these knockout mice had normal heart function and a normal lifespan. Furthermore, Mfn-1 and Mfn-2 deficient mitochondria exhibited normal respiratory function in vitro. We also tested the susceptibility of Mfu-1 and Mfu-2 mitochondria against stress and unexpectedly found that the absence of these proteins conferred resistance to mitochondrial permeability transition (MPT). MPT reflects the loss of membrane integrity in mitochondria and is strongly associated with cell death. Using isolated adult cardiac myocytes we were able to demonstrate that the cell death in either Mfu-1 KO or Mfn-2 KO cells was delayed, consistent with the idea that MPT is attenuated in the absence of these proteins. We also utilized Mfn-2 KO mice to demonstrate that loss of Mfn-2 was associated with protection against cardiac ischemia/reperfusion injury, a stress model strongly linked to MPT. This work suggested for the first time that both Mfu-1 and Mfu-2 have important roles in the process of MPT. To incorporate these novel findings in context with the well-known role of mitofusins in membrane merging, I propose a working model where mitochondrial membrane fusion proceeds through formation of transient lipidic pores that compromise mitochondrial membrane integrity and serve as hotspots for MPT in conditions of stress. Lastly, we generated and characterized mice double-knockout (DKO) for Mfu-1 and Mfu-2. These mice are born in the expected ratios but undergo aberrant cardiac remodelling during the first week of their life and eventually succumb. The DKO mitochondria present multiple morphological and molecular abnormalities. This latter work illustrates that Mfn-1 and Mfn-2 operate interchangeably to regulate the early postnatal development of cardiac myocytes.en_US
dc.language.isoen_US
dc.publisherBoston Universityen_US
dc.titleConsequences of mitofusin ablation in cardiac myocytes. A genetic study in miceen_US
dc.typeThesis/Dissertationen_US
etd.degree.nameDoctor of Philosophyen_US
etd.degree.leveldoctoralen_US
etd.degree.disciplineMolecular Medicineen_US
etd.degree.grantorBoston Universityen_US


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