Dissertation
Crosstalk at the crossroads: MIRO1 regulates mitochondria ER contact sites and mitochondrial activity in proliferating cells
University of Iowa
Doctor of Philosophy (PhD), University of Iowa
Autumn 2024
DOI: 10.25820/etd.007537
Abstract
Restenosis due to neointima formation continues to be a clinically relevant vascular complication driven by aberrant proliferation of VSMCs. While the effects of cytosolic Ca2+ on cell proliferation are well established, recent data point towards a role for mitochondrial Ca2+ entry to promote VSMC proliferation, in part by increasing ROS production and providing ATP and biosynthetic intermediates. Mitochondria-ER contact sites (MERCS) promote signal transduction to mitochondria and are vital for mitochondrial dynamics, lipid exchange, Ca2+ homeostasis, and energy metabolism. Ca2+ release at MERCS exposes mitochondria to high local [Ca2+] taken up by the mitochondrial Ca2+ uniporter (MCU). MIRO1, an outer mitochondrial membrane GTPase, drives intracellular mitochondrial mobility via the binding of cytosolic Ca2+ to its EF hand domains. Recent studies have shown that MIRO1 associates with the MCU and MERCS. Here, we examined whether mitochondrial metabolism changes during proliferation depend on MERCS dynamics and regulated by MIRO1.
This thesis elucidates the key role of MIRO1 in mitochondria/ER alignment, MERCS formation, and mitochondrial metabolic activity during the cell cycle. Proximity ligation of IP3R and VDAC1, as well as MIRO1 and GRP75 increased during G1/S compared to G0 phase. Split GFP ER/mitochondrial contacts of 40 nm also increased. Mitochondrial [Ca2+], membrane potential, and ATP levels correlated with MERCS formation during the cell cycle. MIRO1 deletion decreased wound healing and blocked G1/S progression, cell cycle-dependent MERCS formation and altered ER Ca2+ release and mitochondrial Ca2+ uptake. MIRO1 mutants lacking the Ca2+-sensitive EF hands or transmembrane domain did not rescue MERCS formation defects. Taken together, this work demonstrates that MIRO1 controls MERCS formation during the cell cycle and increases mitochondrial [Ca2+] that drives metabolic activity and proliferation.
Details
- Title: Subtitle
- Crosstalk at the crossroads: MIRO1 regulates mitochondria ER contact sites and mitochondrial activity in proliferating cells
- Creators
- Benney Timi-epere Endoni
- Contributors
- Isabella M. Grumbach (Advisor)Ethan Anderson (Committee Member)Yuriy Usachev (Committee Member)Renata Pereira Alambert (Committee Member)Matthew Potthoff (Committee Member)
- Resource Type
- Dissertation
- Degree Awarded
- Doctor of Philosophy (PhD), University of Iowa
- Degree in
- Biomedical Science (Molecular Medicine)
- Date degree season
- Autumn 2024
- DOI
- 10.25820/etd.007537
- Publisher
- University of Iowa
- Number of pages
- xvii, 130 pages
- Copyright
- Copyright 2024 Benney T. Endoni
- Language
- English
- Date submitted
- 12/09/2024
- Description illustrations
- Illustrations, tables, graphs, charts
- Description bibliographic
- Includes bibliographical references (pages 116-130).
- Public Abstract (ETD)
Atherosclerosis is a very common disease of the vessels in the body that transport blood, for example in the heart and brain. It is a leading cause of illness and death worldwide. The disease makes the blood vessels to become thick, hard, and narrow. This lowers the blood flow in the heart and brain and can cause a heart attack or stroke. Doctors use a method called balloon angioplasty to open narrowed or blocked arteries. But in many patients, the artery that was opened becomes narrowed and blocked again over time after the procedure has been performed. This is due to rapid healing and scarring within the blood vessel. The rapid healing is caused by an excessive growth of the smooth muscle cells present in the middle layer of the arteries. Treatments that help to stop this process remain to be uncovered. Therefore, discovering previously untested mechanisms that control the growth of smooth muscle cells will lead to a better understanding and development of new treatment options. The work in this thesis characterized the connection between mitochondria, the powerhouse of the cells that makes energy for growth and another part of the cell where calcium is stored. Removing an anchor that makes mitochondria move interrupts that connection and stops mitochondria from taking up calcium which it needs to make energy need for cell growth. I hope that the results of my work can help us find new ways to block cell growth after angioplasty and make new drugs to treat atherosclerosis.
- Academic Unit
- Biomedical Science Program
- Record Identifier
- 9984774867302771
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