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Elgass KD, Smith EA, LeGros MA, Larabell CA, Ryan MT. Analysis of ER-mitochondria contacts using correlative fluorescence microscopy and soft X-ray tomography of mammalian cells. J Cell Sci 2015; 128:2795-804. [PMID: 26101352 DOI: 10.1242/jcs.169136] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 06/17/2015] [Indexed: 01/04/2023] Open
Abstract
Mitochondrial fission is important for organelle transport, quality control and apoptosis. Changes to the fission process can result in a wide variety of neurological diseases. In mammals, mitochondrial fission is executed by the GTPase dynamin-related protein 1 (Drp1; encoded by DNM1L), which oligomerizes around mitochondria and constricts the organelle. The mitochondrial outer membrane proteins Mff, MiD49 (encoded by MIEF2) and MiD51 (encoded by MIEF1) are involved in mitochondrial fission by recruiting Drp1 from the cytosol to the organelle surface. In addition, endoplasmic reticulum (ER) tubules have been shown to wrap around and constrict mitochondria before a fission event. Up to now, the presence of MiD49 and MiD51 at ER-mitochondrial division foci has not been established. Here, we combine confocal live-cell imaging with correlative cryogenic fluorescence microscopy and soft x-ray tomography to link MiD49 and MiD51 to the involvement of the ER in mitochondrial fission. We gain further insight into this complex process and characterize the 3D structure of ER-mitochondria contact sites.
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Affiliation(s)
- Kirstin D Elgass
- Hudson Institute for Medical Research, Monash Micro Imaging, Monash University, Melbourne 3168, Australia
| | - Elizabeth A Smith
- Department of Anatomy, School of Medicine, University of California San Francisco, San Francisco, CA 94158, USA National Centre for X-ray Tomography, Advanced Light Source, Berkeley, CA 94720, USA
| | - Mark A LeGros
- Department of Anatomy, School of Medicine, University of California San Francisco, San Francisco, CA 94158, USA National Centre for X-ray Tomography, Advanced Light Source, Berkeley, CA 94720, USA
| | - Carolyn A Larabell
- Department of Anatomy, School of Medicine, University of California San Francisco, San Francisco, CA 94158, USA National Centre for X-ray Tomography, Advanced Light Source, Berkeley, CA 94720, USA
| | - Michael T Ryan
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Melbourne 3800, Australia
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Clowney EJ, LeGros MA, Mosley CP, Clowney FG, Markenskoff-Papadimitriou EC, Myllys M, Barnea G, Larabell CA, Lomvardas S. Nuclear aggregation of olfactory receptor genes governs their monogenic expression. Cell 2012; 151:724-737. [PMID: 23141535 PMCID: PMC3659163 DOI: 10.1016/j.cell.2012.09.043] [Citation(s) in RCA: 237] [Impact Index Per Article: 19.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Revised: 05/18/2012] [Accepted: 09/26/2012] [Indexed: 12/13/2022]
Abstract
Gene positioning and regulation of nuclear architecture are thought to influence gene expression. Here, we show that, in mouse olfactory neurons, silent olfactory receptor (OR) genes from different chromosomes converge in a small number of heterochromatic foci. These foci are OR exclusive and form in a cell-type-specific and differentiation-dependent manner. The aggregation of OR genes is developmentally synchronous with the downregulation of lamin b receptor (LBR) and can be reversed by ectopic expression of LBR in mature olfactory neurons. LBR-induced reorganization of nuclear architecture and disruption of OR aggregates perturbs the singularity of OR transcription and disrupts the targeting specificity of the olfactory neurons. Our observations propose spatial sequestering of heterochromatinized OR family members as a basis of monogenic and monoallelic gene expression.
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Affiliation(s)
- E Josephine Clowney
- Program in Biomedical Sciences, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Mark A LeGros
- Department of Anatomy, University of California, San Francisco, San Francisco, CA 94158, USA; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Colleen P Mosley
- Department of Anatomy, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Fiona G Clowney
- Department of Anatomy, University of California, San Francisco, San Francisco, CA 94158, USA
| | | | - Markko Myllys
- Department of Physics, University of Jyväskylä, Jyväskylä FI-40014, Finland
| | - Gilad Barnea
- Department of Neuroscience, Brown University, Providence, RI 02912, USA
| | - Carolyn A Larabell
- Department of Anatomy, University of California, San Francisco, San Francisco, CA 94158, USA; Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Stavros Lomvardas
- Program in Biomedical Sciences, University of California, San Francisco, San Francisco, CA 94158, USA; Department of Anatomy, University of California, San Francisco, San Francisco, CA 94158, USA; Program in Neurosciences, University of California, San Francisco, San Francisco, CA 94158, USA.
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Miao J, Hodgson KO, Ishikawa T, Larabell CA, LeGros MA, Nishino Y. Imaging whole Escherichia coli bacteria by using single-particle x-ray diffraction. Proc Natl Acad Sci U S A 2003; 100:110-2. [PMID: 12518059 PMCID: PMC140897 DOI: 10.1073/pnas.232691299] [Citation(s) in RCA: 128] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We report the first experimental recording, to our knowledge, of the diffraction pattern from intact Escherichia coli bacteria using coherent x-rays with a wavelength of 2 A. By using the oversampling phasing method, a real space image at a resolution of 30 nm was directly reconstructed from the diffraction pattern. An R factor used for characterizing the quality of the reconstruction was in the range of 5%, which demonstrated the reliability of the reconstruction process. The distribution of proteins inside the bacteria labeled with manganese oxide has been identified and this distribution confirmed by fluorescence microscopy images. Compared with lens-based microscopy, this diffraction-based imaging approach can examine thicker samples, such as whole cultured cells, in three dimensions with resolution limited only by radiation damage. Looking forward, the successful recording and reconstruction of diffraction patterns from biological samples reported here represent an important step toward the potential of imaging single biomolecules at near-atomic resolution by combining single-particle diffraction with x-ray free electron lasers.
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Affiliation(s)
- Jianwei Miao
- Stanford Synchrotron Radiation Laboratory, Stanford Linear Accelerator Center, Stanford University, CA 94309-0210, USA.
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