The mycotoxin phomoxanthone A disturbs the form and function of the inner mitochondrial membrane

AbstractMitochondria perform a plethora of functions in various cells of different tissues. Their architecture differs remarkably, for instance in neurons versus steroidogenic cells. Furthermore, aberrant mitochondrial architecture results in mitochondrial dysfunction. This indicates strongly that mitochondrial architecture and function are intimately linked. Therefore, a deep knowledge about the determinants of mitochondrial architecture and their function on a molecular level is of utmost importance. In the past decades, various proteins and protein complexes essential for formation of mitochondrial architecture have been identified. Here we will review the current knowledge of the MICOS complex, one of the major structural elements of mitochondria. MICOS is a multi-subunit complex present in the inner mitochondrial membrane. Multiple interaction partners in the inner and outer mitochondrial membrane point to participation in a multitude of important processes, such as generation of mitochondrial architecture, lipid metabolism, and protein import into mitochondria. Since the MICOS complex is highly conserved in form and function throughout evolution, we will highlight the importance of MICOS for mammals. We will emphasize in particular the current knowledge of the association of MICOS with severe human diseases, including Charcot–Marie–Tooth disease type 2, Alzheimer's disease, Parkinson's disease, Frontotemporal Dementia and Amyotrophic Lateral Sclerosis.

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Modulation and Analysis of Structure and Function of the Inner Mitochondrial Membrane Through the Application of Phospholipid Enrichment and Membrane Fusion Techniques

Membrane Fusion ◽

10.1201/9780367811525-35 ◽

2019 ◽

pp. 803-844

Author(s):

Brad Chazotte ◽

Charles R. Hackenbrock

Keyword(s):

Membrane Fusion ◽

Mitochondrial Membrane ◽

Structure And Function ◽

Inner Mitochondrial Membrane ◽

And Function

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Transmembrane BAX Inhibitor-1 Motif Containing Protein 5 (TMBIM5) Sustains Mitochondrial Structure, Shape, and Function by Impacting the Mitochondrial Protein Synthesis Machinery

Cells ◽

10.3390/cells9102147 ◽

2020 ◽

Vol 9 (10) ◽

pp. 2147

Author(s):

Bruno Seitaj ◽

Felicia Maull ◽

Li Zhang ◽

Verena Wüllner ◽

Christina Wolf ◽

...

Keyword(s):

Cell Death ◽

Protein Synthesis ◽

Mitochondrial Membrane ◽

Mitochondrial Protein ◽

Mitochondrial Protein Synthesis ◽

Inner Mitochondrial Membrane ◽

Mitochondrial Structure ◽

Protein Synthesis Machinery ◽

Atp Generation ◽

And Function

The Transmembrane Bax Inhibitor-1 motif (TMBIM)-containing protein family is evolutionarily conserved and has been implicated in cell death susceptibility. The only member with a mitochondrial localization is TMBIM5 (also known as GHITM or MICS1), which affects cristae organization and associates with the Parkinson’s disease-associated protein CHCHD2 in the inner mitochondrial membrane. We here used CRISPR-Cas9-mediated knockout HAP1 cells to shed further light on the function of TMBIM5 in physiology and cell death susceptibility. We found that compared to wild type, TMBIM5-knockout cells were smaller and had a slower proliferation rate. In these cells, mitochondria were more fragmented with a vacuolar cristae structure. In addition, the mitochondrial membrane potential was reduced and respiration was attenuated, leading to a reduced mitochondrial ATP generation. TMBIM5 did not associate with Mic10 and Mic60, which are proteins of the mitochondrial contact site and cristae organizing system (MICOS), nor did TMBIM5 knockout affect their expression levels. TMBIM5-knockout cells were more sensitive to apoptosis elicited by staurosporine and BH3 mimetic inhibitors of Bcl-2 and Bcl-XL. An unbiased proteomic comparison identified a dramatic downregulation of proteins involved in the mitochondrial protein synthesis machinery in TMBIM5-knockout cells. We conclude that TMBIM5 is important to maintain the mitochondrial structure and function possibly through the control of mitochondrial biogenesis.

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Abstract 15070: Micu1 Regulates Mitochondrial Cristae Structure and Function Independent of the Mitochondrial Calcium Uniporter Channel

Circulation ◽

10.1161/circ.142.suppl_3.15070 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Dhanendra Tomar ◽

Manfred Thomas ◽

Joanne Garbincius ◽

Devin Kolmetzky ◽

Oniel Salik ◽

...

Keyword(s):

Mitochondrial Membrane ◽

Coiled Coil ◽

Structure And Function ◽

Membrane Dynamics ◽

Size Exclusion ◽

Null Mouse ◽

Intermembrane Space ◽

Inner Mitochondrial Membrane ◽

Cytochrome C Release ◽

And Function

Background: MICU1 is an EF-hand domain containing Ca 2+ -sensor regulating the mitochondrial Ca 2+ uniporter channel and mitochondrial Ca 2+ uptake. MICU1-null mouse and fly models display perinatal lethality with disorganized mitochondrial architecture. Interestingly, these phenotypes are distinct from other mtCU loss-of-function models ( MCU, MICU2, EMRE, MCUR1 ) and thus are likely not explained solely by changes in matrix Ca 2+ content. Using size-exclusion proteomics and co-immunofluorescence, we found that MICU1 localizes to mitochondrial complexes lacking MCU. These observations suggest that MICU1 may have additional cellular functions independent of the MCU. Methods: Biotin-based proximity labeling and proteomics, protein biochemistry, live-cell Ca 2+ imaging, electron microscopy, confocal and super-resolution imaging were utilized to identify and validate MICU1 novel functions. Results: The expression of a MICU1-BioID2 fusion protein in MCU +/+ and MCU -/- cells allowed the identification of the total vs. MCU-independent MICU1 interactome. LC-MS analysis of purified biotinylated proteins identified the mitochondrial contact site and cristae organizing system (MICOS) components Mitofilin (MIC60) and Coiled-coil-helix-coiled-coil helix domain containing 2 (CHCHD2) as MCU independent novel MICU1 interactors. We demonstrate that MICU1 is essential for proper organization of the MICOS complex and that MICU1 ablation results in altered cristae organization, mitochondrial ultrastructure, mitochondrial membrane dynamics, membrane potential, and cell death signaling. We hypothesize that MICU1 is a MICOS Ca 2+ - sensor since perturbing MICU1 is sufficient to modulate cytochrome c release independent of Ca 2+ uptake across the inner mitochondrial membrane. Conclusions: Here, we provide the first experimental evidence of an intermembrane space Ca 2+ - sensor regulating mitochondrial membrane dynamics, independent of changes in matrix Ca 2+ content. This study provides a novel paradigm to understand Ca 2+ -dependent regulation of mitochondrial structure and function and may help explain the mitochondrial remodeling reported to occur in numerous disease states.

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Studies on mitochondrial structure and function in Physarum polycephalum. V. Behaviour of mitochondrial nucleoids throughout mitochondrial division cycle.

The Journal of Cell Biology ◽

10.1083/jcb.72.3.687 ◽

1977 ◽

Vol 72 (3) ◽

pp. 687-694 ◽

Cited By ~ 33

Author(s):

T Kuroiwa ◽

S Kawano ◽

M Hizume

Keyword(s):

Physarum Polycephalum ◽

Mitochondrial Membrane ◽

Light And Electron Microscopy ◽

Structure And Function ◽

Inner Mitochondrial Membrane ◽

Mitochondrial Division ◽

Mitochondrial Structure ◽

Mitochondrial Nucleoids ◽

And Function ◽

Narrow Bridge

The fine structure of mitochondria and mitochondrial nucleoids in exponentially growing Physarum polycephalum was studied at various periods throughout the mitochondrial division cycle by light and electron microscopy. The mitochondrial nucleoid elongates lingitudinally while the mitochondrion increases in size. When the nucleoid reaches a length of approximately 1.5 mum the mitochondrial membrane invaginates at the center of the mitochondrion and separates the mitochondrial contents. However, the nucleoid does not divide even when the mitochondrial sections are connected by a very narrow bridge. Just before division of the mitochondrion, the nucleoid divides by constriction of the limiting membrane of the dividing mitochondrion. After division, one end of the nucleoid appears to be associated with the inner mitochondrial membrane. The nucleoid then again becomes situated in the center of the mitochondrion before repeating these same processes.

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Rbfox2 is Critical for Maintaining Alternative Polyadenylation and Mitochondrial Health in Myoblasts

10.1101/2020.05.13.093013 ◽

2020 ◽

Author(s):

Jun Cao ◽

Elizabeth Jaworski ◽

Kempaiah Rayavara ◽

KarryAnne Belanger ◽

Amanda Sooter ◽

...

Keyword(s):

Mitochondrial Membrane ◽

Rna Binding ◽

Heart Diseases ◽

Mitochondrial Gene ◽

Alternative Polyadenylation ◽

Mitochondrial Genes ◽

Fine Tuning ◽

Inner Mitochondrial Membrane ◽

Altered Expression ◽

And Function

ABSTRACTThe RNA binding protein RBFOX2 is linked to heart and skeletal muscle diseases; yet, RBFOX2-regulated RNA networks have not been systematically identified. Although RBFOX2 has a well-known function in alternative splicing (AS), it is unclear whether RBFOX2 has other roles in RNA metabolism that affect gene expression and function. Utilizing state of the art techniques Poly(A)-ClickSeq (PAC-seq) and nanopore cDNA sequencing, we revealed a new role for RBFOX2 in fine tuning alternative polyadenylation (APA) of pre-mRNAs in myoblasts. We found that depletion of RBFOX2 altered expression of mitochondrial genes. We identified the mitochondrial gene Slc25a4 gene that transports ATP/ADP across inner mitochondrial membrane as a target of RBFOX2. Dissecting how RBFOX2 affects Slc25a4 APA uncovered that RBFOX2 binding motifs near the distal polyadenylation site (PAS) are critical for expression of Slc25a4. Consistent with changes in expression of mitochondrial genes, loss of RBFOX2 altered mitochondrial membrane potential and induced mitochondrial swelling. Our results unveiled a novel role for RBFOX2 in maintaining APA decisions and expression of mitochondrial genes in myoblasts relevant to heart diseases.

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APPROACHES TO THE RELATION OF STRUCTURE AND FUNCTION OF THE INNER MITOCHONDRIAL MEMBRANE

Probes and Membrane Function ◽

10.1016/b978-0-12-167801-2.50055-4 ◽

1971 ◽

pp. 371-376

Author(s):

Efraim Racker

Keyword(s):

Mitochondrial Membrane ◽

Structure And Function ◽

Inner Mitochondrial Membrane ◽

And Function

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ROLE OF ADENINE NUCLEOTIDES IN THE STRUCTURE AND FUNCTION OF THE ATP-ASE OF THE INNER MITOCHONDRIAL MEMBRANE

The Structural Basis of Membrane Function ◽

10.1016/b978-0-12-332450-4.50013-5 ◽

1976 ◽

pp. 69-79 ◽

Cited By ~ 1

Author(s):

Harvey S. Penefsky ◽

Neil E. Garrett ◽

Ta-min Chang

Keyword(s):

Mitochondrial Membrane ◽

Adenine Nucleotides ◽

Structure And Function ◽

Inner Mitochondrial Membrane ◽

And Function

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Structure and function of Pet100p, a molecular chaperone required for the assembly of cytochrome c oxidase in Saccharomyces cerevisiae

Biochemical Society Transactions ◽

10.1042/bst0290436 ◽

2001 ◽

Vol 29 (4) ◽

pp. 436-441 ◽

Cited By ~ 12

Author(s):

D. Forsha ◽

C. Church ◽

P. Wazny ◽

R. O. Poyton

Keyword(s):

Cytochrome C ◽

Cytochrome C Oxidase ◽

Molecular Chaperone ◽

Mitochondrial Membrane ◽

Protein Complexes ◽

Structure And Function ◽

Eukaryotic Cells ◽

Mitochondrial Membranes ◽

Inner Mitochondrial Membrane ◽

And Function

The assembly of cytochrome c oxidase in the inner mitochondrial membranes of eukaryotic cells requires the protein products of a large number of nuclear genes. In yeast, some of these act globally and affect the assembly of several respiratory-chain protein complexes, whereas others act in a cytochrome c oxidase-specific fashion. Many of these yeast proteins have human counterparts, which when mutated lead to energy-related diseases. One of these proteins, Pet100p, is a novel molecular chaperone that functions to incorporate a subcomplex containing cytochrome c oxidase subunits VII, VIIa and VIII into holo-(cytochrome c oxidase). Here we report the topological disposition of Pet100p in the inner mitochondrial membrane and show that its C-terminal domain is essential for its function as a cytochrome c oxidase-specific ‘assembly facilitator’.

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MICU1 regulates mitochondrial cristae structure and function independent of the mitochondrial calcium uniporter channel

10.1101/803213 ◽

2019 ◽

Author(s):

Dhanendra Tomar ◽

Manfred Thomas ◽

Joanne F. Garbincius ◽

Devin W. Kolmetzky ◽

Oniel Salik ◽

...

Keyword(s):

Mitochondrial Membrane ◽

Mitochondrial Protein ◽

Coiled Coil ◽

Membrane Dynamics ◽

Size Exclusion ◽

Mitochondrial Calcium ◽

Cellular Functions ◽

Inner Mitochondrial Membrane ◽

Cytochrome C Release ◽

And Function

AbstractMICU1 is an EF-hand-containing mitochondrial protein that is essential for gating of the mitochondrial Ca2+ uniporter channel (mtCU) and is reported to interact directly with the pore-forming subunit, MCU and scaffold EMRE. However, using size-exclusion proteomics, we found that MICU1 exists in mitochondrial complexes lacking MCU. This suggests that MICU1 may have additional cellular functions independent of regulating mitochondrial Ca2+ uptake. To discern mtCU-independent MICU1 functions, we employed a proteomic discovery approach using BioID2-mediated proximity-based (<10nm) biotinylation and subsequent LC-MS detection. The expression of a MICU1-BioID2 fusion protein in MICU1-/- and MCU-/- cells allowed the identification of total vs. mtCU-independent MICU1 interactors. Bioinformatics identified the Mitochondrial Contact Site and Cristae Organizing System (MICOS) components MIC60 (encoded by the IMMT gene) and Coiled-coil-helix-coiled-coil helix domain containing 2 (CHCHD2) as novel MICU1 interactors, independent of the mtCU. We demonstrate that MICU1 is essential for proper proteomic organization of the MICOS complex and that MICU1 ablation results in altered cristae organization and mitochondrial ultrastructure. We hypothesize that MICU1 serves as a MICOS calcium sensor, since perturbing MICU1 is sufficient to modulate cytochrome c release independent of mitochondrial Ca2+ uptake across the inner mitochondrial membrane (IMM). Here, we provide the first experimental evidence suggesting that MICU1 regulates cellular functions independent of mitochondrial calcium uptake and may serve as a critical mediator of Ca2+-dependent signaling to modulate mitochondrial membrane dynamics and cristae organization.

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