Difference between revisions of "Talk:Cell Mitochondria"

From CellBiology
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==2014==
 
==2014==
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PLoS One. 2013 Oct 18;8(10):e76941. doi: 10.1371/journal.pone.0076941. eCollection 2013.
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Sigma-1 receptor chaperone at the ER-mitochondrion interface mediates the mitochondrion-ER-nucleus signaling for cellular survival.
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Mori T1, Hayashi T, Hayashi E, Su TP.
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Author information
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Abstract
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The membrane of the endoplasmic reticulum (ER) of a cell forms contacts directly with mitochondria whereby the contact is referred to as the mitochondrion-associated ER membrane or the MAM. Here we found that the MAM regulates cellular survival via an MAM-residing ER chaperone the sigma-1 receptor (Sig-1R) in that the Sig-1R chaperones the ER stress sensor IRE1 to facilitate inter-organelle signaling for survival. IRE1 is found in this study to be enriched at the MAM in CHO cells. We found that IRE1 is stabilized at the MAM by Sig-1Rs when cells are under ER stress. Sig-1Rs stabilize IRE1 and thus allow for conformationally correct IRE1 to dimerize into the long-lasting, activated endonuclease. The IRE1 at the MAM also responds to reactive oxygen species derived from mitochondria. Therefore, the ER-mitochondrion interface serves as an important subcellular entity in the regulation of cellular survival by enhancing the stress-responding signaling between mitochondria, ER, and nucleus.
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PMID 24204710
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Int J Cell Biol. 2014;2014:709828. Epub 2014 Jan 22.
 
Int J Cell Biol. 2014;2014:709828. Epub 2014 Jan 22.

Revision as of 23:19, 31 March 2014

2014

PLoS One. 2013 Oct 18;8(10):e76941. doi: 10.1371/journal.pone.0076941. eCollection 2013. Sigma-1 receptor chaperone at the ER-mitochondrion interface mediates the mitochondrion-ER-nucleus signaling for cellular survival. Mori T1, Hayashi T, Hayashi E, Su TP. Author information

Abstract The membrane of the endoplasmic reticulum (ER) of a cell forms contacts directly with mitochondria whereby the contact is referred to as the mitochondrion-associated ER membrane or the MAM. Here we found that the MAM regulates cellular survival via an MAM-residing ER chaperone the sigma-1 receptor (Sig-1R) in that the Sig-1R chaperones the ER stress sensor IRE1 to facilitate inter-organelle signaling for survival. IRE1 is found in this study to be enriched at the MAM in CHO cells. We found that IRE1 is stabilized at the MAM by Sig-1Rs when cells are under ER stress. Sig-1Rs stabilize IRE1 and thus allow for conformationally correct IRE1 to dimerize into the long-lasting, activated endonuclease. The IRE1 at the MAM also responds to reactive oxygen species derived from mitochondria. Therefore, the ER-mitochondrion interface serves as an important subcellular entity in the regulation of cellular survival by enhancing the stress-responding signaling between mitochondria, ER, and nucleus. PMID 24204710


Int J Cell Biol. 2014;2014:709828. Epub 2014 Jan 22. Formation and Regulation of Mitochondrial Membranes. Schenkel LC, Bakovic M. Author information

Abstract Mitochondrial membrane phospholipids are essential for the mitochondrial architecture, the activity of respiratory proteins, and the transport of proteins into the mitochondria. The accumulation of phospholipids within mitochondria depends on a coordinate synthesis, degradation, and trafficking of phospholipids between the endoplasmic reticulum (ER) and mitochondria as well as intramitochondrial lipid trafficking. Several studies highlight the contribution of dietary fatty acids to the remodeling of phospholipids and mitochondrial membrane homeostasis. Understanding the role of phospholipids in the mitochondrial membrane and their metabolism will shed light on the molecular mechanisms involved in the regulation of mitochondrial function and in the mitochondrial-related diseases.


phosphatidylglycerol (PG) and cardiolipin (CL), are exclusively components of mitochondrial membrane (Figure 1). PC and PE are the most abundant phospholipids, comprising 40 and 30% of total mitochondrial phospholipids, respectively. PA and PS comprise 5% of the total mitochondrial phospholipids [6, 7]. Unlike plasma membrane, mitochondrial membranes contain high levels of cardiolipin (~15% of total phospholipids) and low levels of sphingolipids and cholesterol


PMID 24578708

Biochim Biophys Acta. 2014 Apr;1841(4):595-609. doi: 10.1016/j.bbalip.2013.11.014. Epub 2013 Dec 6. MAM (mitochondria-associated membranes) in mammalian cells: Lipids and beyond. Vance JE. Author information

Abstract One mechanism by which communication between the endoplasmic reticulum (ER) and mitochondria is achieved is by close juxtaposition between these organelles via mitochondria-associated membranes (MAM). The MAM consist of a region of the ER that is enriched in several lipid biosynthetic enzyme activities and becomes reversibly tethered to mitochondria. Specific proteins are localized, sometimes transiently, in the MAM. Several of these proteins have been implicated in tethering the MAM to mitochondria. In mammalian cells, formation of these contact sites between MAM and mitochondria appears to be required for key cellular events including the transport of calcium from the ER to mitochondria, the import of phosphatidylserine into mitochondria from the ER for decarboxylation to phosphatidylethanolamine, the formation of autophagosomes, regulation of the morphology, dynamics and functions of mitochondria, and cell survival. This review focuses on the functions proposed for MAM in mediating these events in mammalian cells. In light of the apparent involvement of MAM in multiple fundamental cellular processes, recent studies indicate that impaired contact between MAM and mitochondria might underlie the pathology of several human neurodegenerative diseases, including Alzheimer's disease. Moreover, MAM has been implicated in modulating glucose homeostasis and insulin resistance, as well as in some viral infections. Copyright © 2013 Elsevier B.V. All rights reserved. KEYWORDS: Apoptosis, Autophagy, Endoplasmic reticulum, Lipid transport, Mitochondria, Neurodegeneration

PMID 24316057

Lecture Audio 2013

The University has a system for automated recording of lectures called Lectopia. Lectopia requires login using your student number and unipass. I will be adding the link to each iLecture Audio following the Lecture. Due to the automated recording method, most lectures begin 4-5 minutes into MP3 recordings and occasionally stop before the lecture does.


Archive: 2013 | 2012 | Printable version 2012 Lecture | 2010 | 2009

MH - note that content will not match exactly current lecture structure but has been selected as having similar content


2008 | 2007 Lecture Slides PDF

Movie Powering the Cell - Mitochondria

New insights into the role of mitochondria-associated endoplasmic reticulum membrane

Int Rev Cell Mol Biol. 2011;292:73-117.

Fujimoto M, Hayashi T. Source Cellular Stress Signaling Unit, Cellular Pathobiology Section, Integrative Neuroscience Branch, Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, DHHS, Baltimore, Maryland, USA.

Abstract

The mitochondria-associated endoplasmic reticulum membrane (MAM) is a specialized subdomain of the endoplasmic reticulum (ER) membrane that regulates ER-mitochondria communications. The MAM is characterized by direct apposition to a mitochondrion, a unique lipid profile, and the expression of a unique set of proteins involved in Ca(2+) signaling, phospholipid biosynthesis, protein folding, and membrane tethering. The association of the MAM with a mitochondrion is in part cytoskeleton independent and dynamically changed by an elevation of the cytosolic Ca(2+) level. The mechanisms underlying the genesis of MAM are unclear but might involve COPI-dependent vesicular transport and soluble NSF attachment protein receptor. The MAM is recognized as a center for intermembrane transport of phospholipids and for direct Ca(2+) transmission to mitochondria that activates the tricarboxylic acid cycle. However, MAM might be also involved in the interorganelle transport of cholesterol, ceramides, ATP, and proteins as well as in proteasomal protein degradation and lipid droplet formation. Recent studies have begun to unveil the importance of interorganelle communication in the innate immune response to virus infection and in the pathophysiology of neurodegenerative/neurodevelopmental disorders. Thus, drug discovery aimed at regulating ER-to-mitochondria communication may open a new avenue in treatments of human diseases. Copyright © 2011 Elsevier Inc. All rights reserved.

PMID 22078959


2010

Mitochondria and the culture of the Borg: understanding the integration of mitochondrial function within the reticulum, the cell, and the organism

Bioessays. 2010 Nov;32(11):958-66. doi: 10.1002/bies.201000073. Epub 2010 Sep 7.

Braschi E, McBride HM. Source University of Ottawa Heart Institute, Ottawa, Ontario, Canada. Abstract As endosymbionts, the mitochondria are unique among organelles. This review provides insights into mitochondrial behavior and introduces the idea of a unified collective, an interconnected reticulum reminiscent of the Borg, a fictional humanoid species from the Star Trek television series whereby decisions are made within their network (or "hive"), linked to signaling cascades that coordinate the cross-talk between mitochondrial and cellular processes ("subspace domain"). Similarly, mitochondrial dynamics are determined by two distinct processes, namely the local regulation of fission/fusion and the global control of their behavior through cellular signaling pathways. Indeed, decisions within the hive provide each mitochondrial unit with autonomous control of their own degradation, whereby mitochondrial fusion is inactivated and they become substrates for autophagy. Decisions within the subspace domain couple signaling pathways involved in the functional integration of mitochondria with complex cellular transitions, including developmental cues, mitosis, and apoptosis. Copyright © 2010 WILEY Periodicals, Inc.

PMID 20824657


Cytochrome c maintains mitochondrial transmembrane potential and ATP generation after outer mitochondrial membrane permeabilization during the apoptotic process

J Cell Biol. 2001 Apr 16;153(2):319-28.

Waterhouse NJ, Goldstein JC, von Ahsen O, Schuler M, Newmeyer DD, Green DR.

Division of Cellular Immunology, La Jolla Institute for Allergy and Immunology, San Diego, California 92121, USA.

Abstract

During apoptosis, cytochrome c is released into the cytosol as the outer membrane of mitochondria becomes permeable, and this acts to trigger caspase activation. The consequences of this release for mitochondrial metabolism are unclear. Using single-cell analysis, we found that when caspase activity is inhibited, mitochondrial outer membrane permeabilization causes a rapid depolarization of mitochondrial transmembrane potential, which recovers to original levels over the next 30-60 min and is then maintained. After outer membrane permeabilization, mitochondria can use cytoplasmic cytochrome c to maintain mitochondrial transmembrane potential and ATP production. Furthermore, both cytochrome c release and apoptosis proceed normally in cells in which mitochondria have been uncoupled. These studies demonstrate that cytochrome c release does not affect the integrity of the mitochondrial inner membrane and that, in the absence of caspase activation, mitochondrial functions can be maintained after the release of cytochrome c.

PMID: 11309413 http://www.ncbi.nlm.nih.gov/pubmed/11309413

J. Cell Biol. Vol. 153 No. 2 p.319

Waterhouse et al.

Video 1 (1.5MB)

Loss and regeneration of {Delta}{Psi}m after cytochrome c release. Cc-GFP-HeLa cells were treated with actinomycin D (1 µM) in the presence of N-benzoylcarbonyl-Val-Ala-Asp-fluorome-thylketone (zVADfmk) (100 µM), and confocal images were taken every 2 min. The cytochrome c-GFP (green, left) shows the coordinate release of cytochrome c in the individual cells (the staining goes from punctate to diffuse upon release). TMRE fluorescence in the same cells (red, right) shows the loss and recovery of {Delta}{Psi}m. The red and green images are of the same cells taken at the same time. The frames are separate rather than overlaid for clarity, and a mathematical representation of loss and regen-eration of {Delta}{Psi}m in a similarly treated cell is shown in Fig. 4 A.