TY  - JOUR
A1  - Kunz, Tobias C.
A1  - Götz, Ralph
A1  - Gao, Shiqiang
A1  - Sauer, Markus
A1  - Kozjak-Pavlovic, Vera
T1  - Using Expansion Microscopy to Visualize and Characterize the Morphology of Mitochondrial Cristae
JF  - Frontiers in Cell and Developmental Biology
N2  - Mitochondria are double membrane bound organelles indispensable for biological processes such as apoptosis, cell signaling, and the production of many important metabolites, which includes ATP that is generated during the process known as oxidative phosphorylation (OXPHOS). The inner membrane contains folds called cristae, which increase the membrane surface and thus the amount of membrane-bound proteins necessary for the OXPHOS. These folds have been of great interest not only because of their importance for energy conversion, but also because changes in morphology have been linked to a broad range of diseases from cancer, diabetes, neurodegenerative diseases, to aging and infection. With a distance between opposing cristae membranes often below 100 nm, conventional fluorescence imaging cannot provide a resolution sufficient for resolving these structures. For this reason, various highly specialized super-resolution methods including dSTORM, PALM, STED, and SIM have been applied for cristae visualization. Expansion Microscopy (ExM) offers the possibility to perform super-resolution microscopy on conventional confocal microscopes by embedding the sample into a swellable hydrogel that is isotropically expanded by a factor of 4–4.5, improving the resolution to 60–70 nm on conventional confocal microscopes, which can be further increased to ∼ 30 nm laterally using SIM. Here, we demonstrate that the expression of the mitochondrial creatine kinase MtCK linked to marker protein GFP (MtCK-GFP), which localizes to the space between the outer and the inner mitochondrial membrane, can be used as a cristae marker. Applying ExM on mitochondria labeled with this construct enables visualization of morphological changes of cristae and localization studies of mitochondrial proteins relative to cristae without the need for specialized setups. For the first time we present the combination of specific mitochondrial intermembrane space labeling and ExM as a tool for studying internal structure of mitochondria.
KW  - Expansion microscopy
KW  - mitochondria
KW  - cristae
KW  - structured illumination microscope
KW  - ultrastructure
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-208296
SN  - 2296-634X
VL  - 8
ER  - 
TY  - JOUR
A1  - Ott, Christine
A1  - Dorsch, Eva
A1  - Fraunholz, Martin
A1  - Straub, Sebastian
A1  - Kozjak-Pavlovic, Vera
T1  - Detailed Analysis of the Human Mitochondrial Contact Site Complex Indicate a Hierarchy of Subunits
JF  - PLoS One
N2  - Mitochondrial inner membrane folds into cristae, which significantly increase its surface and are important for mitochondrial function. The stability of cristae depends on the mitochondrial contact site (MICOS) complex. In human mitochondria, the inner membrane MICOS complex interacts with the outer membrane sorting and assembly machinery (SAM) complex, to form the mitochondrial intermembrane space bridging complex (MIB). We have created knockdown cell lines of most of the MICOS and MIB components and have used them to study the importance of the individual subunits for the cristae formation and complex stability. We show that the most important subunits of the MIB complex in human mitochondria are Mic60/Mitofilin, Mic19/CHCHD3 and an outer membrane component Sam50. We provide additional proof that ApoO indeed is a subunit of the MICOS and MIB complexes and propose the name Mic23 for this protein. According to our results, Mic25/CHCHD6, Mic27/ApoOL and Mic23/ApoO appear to be periphery subunits of the MICOS complex, because their depletion does not affect cristae morphology or stability of other components.
KW  - co-immunoprecipitation
KW  - motor proteins
KW  - mitochondria
KW  - membrane potential
KW  - membrane proteins
KW  - protein complexes
KW  - mitochondrial membrane
KW  - outer membrane proteins
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-125347
VL  - 10
IS  - 3
ER  -