1
|
Ramms DJ, Raimondi F, Arang N, Herberg FW, Taylor SS, Gutkind JS. G αs-Protein Kinase A (PKA) Pathway Signalopathies: The Emerging Genetic Landscape and Therapeutic Potential of Human Diseases Driven by Aberrant G αs-PKA Signaling. Pharmacol Rev 2021; 73:155-197. [PMID: 34663687 PMCID: PMC11060502 DOI: 10.1124/pharmrev.120.000269] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Many of the fundamental concepts of signal transduction and kinase activity are attributed to the discovery and crystallization of cAMP-dependent protein kinase, or protein kinase A. PKA is one of the best-studied kinases in human biology, with emphasis in biochemistry and biophysics, all the way to metabolism, hormone action, and gene expression regulation. It is surprising, however, that our understanding of PKA's role in disease is largely underappreciated. Although genetic mutations in the PKA holoenzyme are known to cause diseases such as Carney complex, Cushing syndrome, and acrodysostosis, the story largely stops there. With the recent explosion of genomic medicine, we can finally appreciate the broader role of the Gαs-PKA pathway in disease, with contributions from aberrant functioning G proteins and G protein-coupled receptors, as well as multiple alterations in other pathway components and negative regulators. Together, these represent a broad family of diseases we term the Gαs-PKA pathway signalopathies. The Gαs-PKA pathway signalopathies encompass diseases caused by germline, postzygotic, and somatic mutations in the Gαs-PKA pathway, with largely endocrine and neoplastic phenotypes. Here, we present a signaling-centric review of Gαs-PKA-driven pathophysiology and integrate computational and structural analysis to identify mutational themes commonly exploited by the Gαs-PKA pathway signalopathies. Major mutational themes include hotspot activating mutations in Gαs, encoded by GNAS, and mutations that destabilize the PKA holoenzyme. With this review, we hope to incite further study and ultimately the development of new therapeutic strategies in the treatment of a wide range of human diseases. SIGNIFICANCE STATEMENT: Little recognition is given to the causative role of Gαs-PKA pathway dysregulation in disease, with effects ranging from infectious disease, endocrine syndromes, and many cancers, yet these disparate diseases can all be understood by common genetic themes and biochemical signaling connections. By highlighting these common pathogenic mechanisms and bridging multiple disciplines, important progress can be made toward therapeutic advances in treating Gαs-PKA pathway-driven disease.
Collapse
Affiliation(s)
- Dana J Ramms
- Department of Pharmacology (D.J.R., N.A., J.S.G.), Department of Chemistry and Biochemistry (S.S.T.), and Moores Cancer Center (D.J.R., N.A., J.S.G.), University of California, San Diego, La Jolla, California; Laboratorio di Biologia Bio@SNS, Scuola Normale Superiore, Pisa, Italy (F.R.); and Department of Biochemistry, University of Kassel, Kassel, Germany (F.W.H.)
| | - Francesco Raimondi
- Department of Pharmacology (D.J.R., N.A., J.S.G.), Department of Chemistry and Biochemistry (S.S.T.), and Moores Cancer Center (D.J.R., N.A., J.S.G.), University of California, San Diego, La Jolla, California; Laboratorio di Biologia Bio@SNS, Scuola Normale Superiore, Pisa, Italy (F.R.); and Department of Biochemistry, University of Kassel, Kassel, Germany (F.W.H.)
| | - Nadia Arang
- Department of Pharmacology (D.J.R., N.A., J.S.G.), Department of Chemistry and Biochemistry (S.S.T.), and Moores Cancer Center (D.J.R., N.A., J.S.G.), University of California, San Diego, La Jolla, California; Laboratorio di Biologia Bio@SNS, Scuola Normale Superiore, Pisa, Italy (F.R.); and Department of Biochemistry, University of Kassel, Kassel, Germany (F.W.H.)
| | - Friedrich W Herberg
- Department of Pharmacology (D.J.R., N.A., J.S.G.), Department of Chemistry and Biochemistry (S.S.T.), and Moores Cancer Center (D.J.R., N.A., J.S.G.), University of California, San Diego, La Jolla, California; Laboratorio di Biologia Bio@SNS, Scuola Normale Superiore, Pisa, Italy (F.R.); and Department of Biochemistry, University of Kassel, Kassel, Germany (F.W.H.)
| | - Susan S Taylor
- Department of Pharmacology (D.J.R., N.A., J.S.G.), Department of Chemistry and Biochemistry (S.S.T.), and Moores Cancer Center (D.J.R., N.A., J.S.G.), University of California, San Diego, La Jolla, California; Laboratorio di Biologia Bio@SNS, Scuola Normale Superiore, Pisa, Italy (F.R.); and Department of Biochemistry, University of Kassel, Kassel, Germany (F.W.H.)
| | - J Silvio Gutkind
- Department of Pharmacology (D.J.R., N.A., J.S.G.), Department of Chemistry and Biochemistry (S.S.T.), and Moores Cancer Center (D.J.R., N.A., J.S.G.), University of California, San Diego, La Jolla, California; Laboratorio di Biologia Bio@SNS, Scuola Normale Superiore, Pisa, Italy (F.R.); and Department of Biochemistry, University of Kassel, Kassel, Germany (F.W.H.)
| |
Collapse
|
2
|
Koch C, Schuldiner M, Herrmann JM. ER-SURF: Riding the Endoplasmic Reticulum Surface to Mitochondria. Int J Mol Sci 2021; 22:9655. [PMID: 34502567 PMCID: PMC8432098 DOI: 10.3390/ijms22179655] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 08/29/2021] [Indexed: 02/08/2023] Open
Abstract
Most mitochondrial proteins are synthesized in the cytosol and targeted to the mitochondrial surface in a post-translational manner. The surface of the endoplasmic reticulum (ER) plays an active role in this targeting reaction. ER-associated chaperones interact with certain mitochondrial membrane protein precursors and transfer them onto receptor proteins of the mitochondrial surface in a process termed ER-SURF. ATP-driven proteins in the membranes of mitochondria (Msp1, ATAD1) and the ER (Spf1, P5A-ATPase) serve as extractors for the removal of mislocalized proteins. If the re-routing to mitochondria fails, precursors can be degraded by ER or mitochondria-associated degradation (ERAD or MAD respectively) in a proteasome-mediated reaction. This review summarizes the current knowledge about the cooperation of the ER and mitochondria in the targeting and quality control of mitochondrial precursor proteins.
Collapse
Affiliation(s)
- Christian Koch
- Cell Biology, University of Kaiserslautern, 67663 Kaiserslautern, Germany;
| | - Maya Schuldiner
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 7610001, Israel;
| | | |
Collapse
|
3
|
Cenini G, Hebisch M, Iefremova V, Flitsch LJ, Breitkreuz Y, Tanzi RE, Kim DY, Peitz M, Brüstle O. Dissecting Alzheimer's disease pathogenesis in human 2D and 3D models. Mol Cell Neurosci 2021; 110:103568. [DOI: 10.1016/j.mcn.2020.103568] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Revised: 09/30/2020] [Accepted: 10/12/2020] [Indexed: 02/06/2023] Open
|
4
|
Abstract
Mitochondria are essential organelles of eukaryotic cells. They consist of hundreds of different proteins that exhibit crucial activities in respiration, catabolic metabolism and the synthesis of amino acids, lipids, heme and iron-sulfur clusters. With the exception of a handful of hydrophobic mitochondrially encoded membrane proteins, all these proteins are synthesized on cytosolic ribosomes, targeted to receptors on the mitochondrial surface, and transported across or inserted into the outer and inner mitochondrial membrane before they are folded and assembled into their final native structure. This review article provides a comprehensive overview of the mechanisms and components of the mitochondrial protein import systems with a particular focus on recent developments in the field.
Collapse
Affiliation(s)
- Katja G Hansen
- Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Strasse 13, 67663, Kaiserslautern, Germany
| | - Johannes M Herrmann
- Cell Biology, University of Kaiserslautern, Erwin-Schrödinger-Strasse 13, 67663, Kaiserslautern, Germany.
| |
Collapse
|
5
|
A-Kinase Anchoring Protein 1: Emerging Roles in Regulating Mitochondrial Form and Function in Health and Disease. Cells 2020; 9:cells9020298. [PMID: 31991888 PMCID: PMC7072574 DOI: 10.3390/cells9020298] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/1970] [Revised: 01/17/2020] [Accepted: 01/21/2020] [Indexed: 01/01/2023] Open
Abstract
Best known as the powerhouse of the cell, mitochondria have many other important functions such as buffering intracellular calcium and reactive oxygen species levels, initiating apoptosis and supporting cell proliferation and survival. Mitochondria are also dynamic organelles that are constantly undergoing fission and fusion to meet specific functional needs. These processes and functions are regulated by intracellular signaling at the mitochondria. A-kinase anchoring protein 1 (AKAP1) is a scaffold protein that recruits protein kinase A (PKA), other signaling proteins, as well as RNA to the outer mitochondrial membrane. Hence, AKAP1 can be considered a mitochondrial signaling hub. In this review, we discuss what is currently known about AKAP1's function in health and diseases. We focus on the recent literature on AKAP1's roles in metabolic homeostasis, cancer and cardiovascular and neurodegenerative diseases. In healthy tissues, AKAP1 has been shown to be important for driving mitochondrial respiration during exercise and for mitochondrial DNA replication and quality control. Several recent in vivo studies using AKAP1 knockout mice have elucidated the role of AKAP1 in supporting cardiovascular, lung and neuronal cell survival in the stressful post-ischemic environment. In addition, we discuss the unique involvement of AKAP1 in cancer tumor growth, metastasis and resistance to chemotherapy. Collectively, the data indicate that AKAP1 promotes cell survival throug regulating mitochondrial form and function. Lastly, we discuss the potential of targeting of AKAP1 for therapy of various disorders.
Collapse
|
6
|
Haushalter KJ, Schilling JM, Song Y, Sastri M, Perkins GA, Strack S, Taylor SS, Patel HH. Cardiac ischemia-reperfusion injury induces ROS-dependent loss of PKA regulatory subunit RIα. Am J Physiol Heart Circ Physiol 2019; 317:H1231-H1242. [PMID: 31674811 PMCID: PMC6962616 DOI: 10.1152/ajpheart.00237.2019] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 10/21/2019] [Accepted: 10/21/2019] [Indexed: 12/27/2022]
Abstract
Type I PKA regulatory α-subunit (RIα; encoded by the Prkar1a gene) serves as the predominant inhibitor protein of the catalytic subunit of cAMP-dependent protein kinase (PKAc). However, recent evidence suggests that PKA signaling can be initiated by cAMP-independent events, especially within the context of cellular oxidative stress such as ischemia-reperfusion (I/R) injury. We determined whether RIα is actively involved in the regulation of PKA activity via reactive oxygen species (ROS)-dependent mechanisms during I/R stress in the heart. Induction of ex vivo global I/R injury in mouse hearts selectively downregulated RIα protein expression, whereas RII subunit expression appears to remain unaltered. Cardiac myocyte cell culture models were used to determine that oxidant stimulus (i.e., H2O2) alone is sufficient to induce RIα protein downregulation. Transient increase of RIα expression (via adenoviral overexpression) negatively affects cell survival and function upon oxidative stress as measured by increased induction of apoptosis and decreased mitochondrial respiration. Furthermore, analysis of mitochondrial subcellular fractions in heart tissue showed that PKA-associated proteins are enriched in subsarcolemmal mitochondria (SSM) fractions and that loss of RIα is most pronounced at SSM upon I/R injury. These data were supported via electron microscopy in A-kinase anchoring protein 1 (AKAP1)-knockout mice, where loss of AKAP1 expression leads to aberrant mitochondrial morphology manifested in SSM but not interfibrillar mitochondria. Thus, we conclude that modification of RIα via ROS-dependent mechanisms induced by I/R injury has the potential to sensitize PKA signaling in the cell without the direct use of the canonical cAMP-dependent activation pathway.NEW & NOTEWORTHY We uncovered a previously undescribed phenomenon involving oxidation-induced activation of PKA signaling in the progression of cardiac ischemia-reperfusion injury. Type I PKA regulatory subunit RIα, but not type II PKA regulatory subunits, is dynamically regulated by oxidative stress to trigger the activation of the catalytic subunit of PKA in cardiac myocytes. This effect may play a critical role in the regulation of subsarcolemmal mitochondria function upon the induction of ischemic injury in the heart.
Collapse
Affiliation(s)
- Kristofer J Haushalter
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California
- Veterans Affairs San Diego Healthcare System, San Diego, California
| | - Jan M Schilling
- Veterans Affairs San Diego Healthcare System, San Diego, California
- Department of Anesthesiology, University of California, San Diego, La Jolla, California
| | - Young Song
- Veterans Affairs San Diego Healthcare System, San Diego, California
- Department of Anesthesiology and Pain Medicine, Yonsei University College of Medicine, Seoul, South Korea
| | - Mira Sastri
- Department of Pharmacology, University of California, San Diego, La Jolla, California
| | - Guy A Perkins
- National Center for Microscopy and Imaging Research, University of California, San Diego, La Jolla, California
| | - Stefan Strack
- Department of Pharmacology, University of Iowa Carver College of Medicine, Iowa City, Iowa
| | - Susan S Taylor
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California
- Department of Pharmacology, University of California, San Diego, La Jolla, California
| | - Hemal H Patel
- Veterans Affairs San Diego Healthcare System, San Diego, California
- Department of Anesthesiology, University of California, San Diego, La Jolla, California
| |
Collapse
|
7
|
Marin W. A-kinase anchoring protein 1 (AKAP1) and its role in some cardiovascular diseases. J Mol Cell Cardiol 2019; 138:99-109. [PMID: 31783032 DOI: 10.1016/j.yjmcc.2019.11.154] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 11/08/2019] [Accepted: 11/22/2019] [Indexed: 01/09/2023]
Abstract
A-kinase anchoring proteins (AKAPs) play crucial roles in regulating compartmentalized multi-protein signaling networks related to PKA-mediated phosphorylation. The mitochondrial AKAP - AKAP1 proteins are enriched in heart and play cardiac protective roles. This review aims to thoroughly summarize AKAP1 variants from their sequence features to the structure-function relationships between AKAP1 and its binding partners, as well as the molecular mechanisms of AKAP1 in cardiac hypertrophy, hypoxia-induced myocardial infarction and endothelial cells dysfunction, suggesting AKAP1 as a candidate for cardiovascular therapy.
Collapse
Affiliation(s)
- Wenwen Marin
- Institute for Translational Medicine, Medical Faculty of Qingdao University, Qingdao 266021, China.
| |
Collapse
|
8
|
Traub LM. A nanobody-based molecular toolkit provides new mechanistic insight into clathrin-coat initiation. eLife 2019; 8:41768. [PMID: 31038455 PMCID: PMC6524969 DOI: 10.7554/elife.41768] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Accepted: 04/24/2019] [Indexed: 12/21/2022] Open
Abstract
Besides AP-2 and clathrin triskelia, clathrin coat inception depends on a group of early-arriving proteins including Fcho1/2 and Eps15/R. Using genome-edited cells, we described the role of the unstructured Fcho linker in stable AP-2 membrane deposition. Here, expanding this strategy in combination with a new set of llama nanobodies against EPS15 shows an FCHO1/2–EPS15/R partnership plays a decisive role in coat initiation. A nanobody containing an Asn-Pro-Phe peptide within the complementarity-determining region 3 loop is a function-blocking pseudoligand for tandem EPS15/R EH domains. Yet, in living cells, EH domains gathered at clathrin-coated structures are poorly accessible, indicating residence by endogenous NPF-bearing partners. Forcibly sequestering cytosolic EPS15 in genome-edited cells with nanobodies tethered to early endosomes or mitochondria changes the subcellular location and availability of EPS15. This combined approach has strong effects on clathrin coat structure and function by dictating the stability of AP-2 assemblies at the plasma membrane.
Collapse
Affiliation(s)
- Linton M Traub
- Department of Cell Biology, School of Medicine, University of Pittsburgh, Pittsburgh, United States
| |
Collapse
|
9
|
Zhang J, Feng J, Ma D, Wang F, Wang Y, Li C, Wang X, Yin X, Zhang M, Dagda RK, Zhang Y. Neuroprotective Mitochondrial Remodeling by AKAP121/PKA Protects HT22 Cell from Glutamate-Induced Oxidative Stress. Mol Neurobiol 2019; 56:5586-5607. [PMID: 30652267 DOI: 10.1007/s12035-018-1464-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 12/19/2018] [Indexed: 01/05/2023]
Abstract
Protein kinase A (PKA) is a ser/thr kinase that is critical for maintaining essential neuronal functions including mitochondrial homeostasis, bioenergetics, neuronal development, and neurotransmission. The endogenous pool of PKA is targeted to the mitochondrion by forming a complex with the mitochondrial scaffold A-kinase anchoring protein 121 (AKAP121). Enhanced PKA signaling via AKAP121 leads to PKA-mediated phosphorylation of the fission modulator Drp1, leading to enhanced mitochondrial networks and thereby blocking apoptosis against different toxic insults. In this study, we show for the first time that AKAP121/PKA confers neuroprotection in an in vitro model of oxidative stress induced by exposure to excess glutamate. Unexpectedly, treating mouse hippocampal progenitor neuronal HT22 cells with an acute dose or chronic exposure of glutamate robustly elevates PKA signaling, a beneficial compensatory response that is phenocopied in HT22 cells conditioned to thrive in the presence of excess glutamate but not in parental HT22 cells. Secondly, redirecting the endogenous pool of PKA by transiently transfecting AKAP121 or transfecting a constitutively active mutant of PKA targeted to the mitochondrion (OMM-PKA) or of an isoform of AKAP121 that lacks the KH and Tudor domains (S-AKAP84) are sufficient to significantly block cell death induced by glutamate toxicity but not in an oxygen deprivation/reperfusion model. Conversely, transient transfection of HT22 neuronal cells with a PKA-binding-deficient mutant of AKAP121 is unable to protect against oxidative stress induced by glutamate toxicity suggesting that the catalytic activity of PKA is required for AKAP121's protective effects. Mechanistically, AKAP121 promotes neuroprotection by enhancing PKA-mediated phosphorylation of Drp1 to increase mitochondrial fusion, elevates ATP levels, and elicits an increase in the levels of antioxidants GSH and superoxide dismutase 2 leading to a reduction in the level of mitochondrial superoxide. Overall, our data supports AKAP121/PKA as a new molecular target that confers neuroprotection against glutamate toxicity by phosphorylating Drp1, to stabilize mitochondrial networks and mitochondrial function and to elicit antioxidant responses.
Collapse
Affiliation(s)
- Jingdian Zhang
- Department of Neurology and Neuroscience Center, First Hospital of Jilin University, Xinmin Street No. 71, Changchun, 130000, China
| | - Jiachun Feng
- Department of Neurology and Neuroscience Center, First Hospital of Jilin University, Xinmin Street No. 71, Changchun, 130000, China
| | - Di Ma
- Department of Neurology and Neuroscience Center, First Hospital of Jilin University, Xinmin Street No. 71, Changchun, 130000, China
| | - Feng Wang
- National-Local Joint Engineering Laboratory of Animal Models for Human Diseases, Changchun, Jilin, China
| | - Yumeng Wang
- Department of Physiology, College of Basic Medical Sciences, Norman Bethune Health Science Center, Jilin University, Xinmin Street No. 126, Changchun, 130000, China
| | - Chunxiao Li
- Department of Neurology and Neuroscience Center, First Hospital of Jilin University, Xinmin Street No. 71, Changchun, 130000, China
| | - Xu Wang
- Department of Neurology and Neuroscience Center, First Hospital of Jilin University, Xinmin Street No. 71, Changchun, 130000, China
| | - Xiang Yin
- Department of Neurology and Neuroscience Center, First Hospital of Jilin University, Xinmin Street No. 71, Changchun, 130000, China
| | - Ming Zhang
- Department of Pharmacology, College of Basic Medical Sciences, Jilin University, 126 Xin Min Street, Changchun, 130021, Jilin, China
| | - Ruben K Dagda
- Department of Pharmacology, Reno School of Medicine, University of Nevada, Mailstop 318, Howard Medical Sciences Building 148A (Office), Reno, NV, 89557,, USA
| | - Ying Zhang
- Department of Neurology and Neuroscience Center, First Hospital of Jilin University, Xinmin Street No. 71, Changchun, 130000, China.
| |
Collapse
|
10
|
Aggarwal S, Gabrovsek L, Langeberg LK, Golkowski M, Ong SE, Smith FD, Scott JD. Depletion of dAKAP1-protein kinase A signaling islands from the outer mitochondrial membrane alters breast cancer cell metabolism and motility. J Biol Chem 2018; 294:3152-3168. [PMID: 30598507 DOI: 10.1074/jbc.ra118.006741] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 12/21/2018] [Indexed: 01/23/2023] Open
Abstract
Breast cancer screening and new precision therapies have led to improved patient outcomes. Yet, a positive prognosis is less certain when primary tumors metastasize. Metastasis requires a coordinated program of cellular changes that promote increased survival, migration, and energy consumption. These pathways converge on mitochondrial function, where distinct signaling networks of kinases, phosphatases, and metabolic enzymes regulate these processes. The protein kinase A-anchoring protein dAKAP1 compartmentalizes protein kinase A (PKA) and other signaling enzymes at the outer mitochondrial membrane and thereby controls mitochondrial function and dynamics. Modulation of these processes occurs in part through regulation of dynamin-related protein 1 (Drp1). Here, we report an inverse relationship between the expression of dAKAP1 and mesenchymal markers in breast cancer. Molecular, cellular, and in silico analyses of breast cancer cell lines confirmed that dAKAP1 depletion is associated with impaired mitochondrial function and dynamics, as well as with increased glycolytic potential and invasiveness. Furthermore, disruption of dAKAP1-PKA complexes affected cell motility and mitochondrial movement toward the leading edge in invasive breast cancer cells. We therefore propose that depletion of dAKAP1-PKA "signaling islands" from the outer mitochondrial membrane augments progression toward metastatic breast cancer.
Collapse
Affiliation(s)
- Stacey Aggarwal
- From the Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195
| | - Laura Gabrovsek
- From the Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195
| | - Lorene K Langeberg
- From the Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195
| | - Martin Golkowski
- From the Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195
| | - Shao-En Ong
- From the Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195
| | - F Donelson Smith
- From the Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195
| | - John D Scott
- From the Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195
| |
Collapse
|
11
|
AKAP1 Protects from Cerebral Ischemic Stroke by Inhibiting Drp1-Dependent Mitochondrial Fission. J Neurosci 2018; 38:8233-8242. [PMID: 30093535 PMCID: PMC6146498 DOI: 10.1523/jneurosci.0649-18.2018] [Citation(s) in RCA: 78] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 07/29/2018] [Accepted: 08/01/2018] [Indexed: 12/20/2022] Open
Abstract
Mitochondrial fission and fusion impact numerous cellular functions and neurons are particularly sensitive to perturbations in mitochondrial dynamics. Here we describe that male mice lacking the mitochondrial A-kinase anchoring protein 1 (AKAP1) exhibit increased sensitivity in the transient middle cerebral artery occlusion model of focal ischemia. At the ultrastructural level, AKAP1-/- mice have smaller mitochondria and increased contacts between mitochondria and the endoplasmic reticulum in the brain. Mechanistically, deletion of AKAP1 dysregulates complex II of the electron transport chain, increases superoxide production, and impairs Ca2+ homeostasis in neurons subjected to excitotoxic glutamate. Ca2+ deregulation in neurons lacking AKAP1 can be attributed to loss of inhibitory phosphorylation of the mitochondrial fission enzyme dynamin-related protein 1 (Drp1) at the protein kinase A (PKA) site Ser637. Our results indicate that inhibition of Drp1-dependent mitochondrial fission by the outer mitochondrial AKAP1/PKA complex protects neurons from ischemic stroke by maintaining respiratory chain activity, inhibiting superoxide production, and delaying Ca2+ deregulation. They also provide the first genetic evidence that Drp1 inhibition may be of therapeutic relevance for the treatment of stroke and neurodegeneration.SIGNIFICANCE STATEMENT Previous work suggests that activation of dynamin-related protein 1 (Drp1) and mitochondrial fission contribute to ischemic injury in the brain. However, the specificity and efficacy of the pharmacological Drp1 inhibitor mdivi-1 that was used has now been discredited by several high-profile studies. Our report is timely and highly impactful because it provides the first evidence that genetic disinhibition of Drp1 via knock-out of the mitochondrial protein kinase A (PKA) scaffold AKAP1 exacerbates stroke injury in mice. Mechanistically, we show that electron transport deficiency, increased superoxide production, and Ca2+ overload result from genetic disinhibition of Drp1. In summary, our work settles current controversies regarding the role of mitochondrial fission in neuronal injury, provides mechanisms, and suggests that fission inhibitors hold promise as future therapeutic agents.
Collapse
|
12
|
Abstract
3′,5′-cyclic adenosine monophosphate (cAMP) signalling plays a major role in the cardiac myocyte response to extracellular stimulation by hormones and neurotransmitters. In recent years, evidence has accumulated demonstrating that the cAMP response to different extracellular agonists is not uniform: depending on the stimulus, cAMP signals of different amplitudes and kinetics are generated in different subcellular compartments, eliciting defined physiological effects. In this review, we focus on how real-time imaging using fluorescence resonance energy transfer (FRET)-based reporters has provided mechanistic insight into the compartmentalisation of the cAMP signalling pathway and allowed for the precise definition of the regulation and function of subcellular cAMP nanodomains.
Collapse
|
13
|
Chen G, Fu Q, Yu F, Ren R, Liu Y, Cao Z, Li G, Zhao X, Chen L, Wang H, You J. Wide-Acidity-Range pH Fluorescence Probes for Evaluation of Acidification in Mitochondria and Digestive Tract Mucosa. Anal Chem 2017; 89:8509-8516. [DOI: 10.1021/acs.analchem.7b02164] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Guang Chen
- The
Key Laboratory of Life-Organic Analysis; Key Laboratory of Pharmaceutical
Intermediates and Analysis of Natural Medicine, College of Chemistry
and Chemical Engineering, Qufu Normal University, Qufu 273165, China
- Key
Laboratory of Coastal Environmental Processes and Ecological Remediation,
Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
- Shandong
Province Key Laboratory of Detection Technology for Tumor Makers,
College of Chemistry and Chemical Engineering, Linyi University, Linyi 276005, China
| | - Qiang Fu
- The
Key Laboratory of Life-Organic Analysis; Key Laboratory of Pharmaceutical
Intermediates and Analysis of Natural Medicine, College of Chemistry
and Chemical Engineering, Qufu Normal University, Qufu 273165, China
| | - Fabiao Yu
- The
Key Laboratory of Life-Organic Analysis; Key Laboratory of Pharmaceutical
Intermediates and Analysis of Natural Medicine, College of Chemistry
and Chemical Engineering, Qufu Normal University, Qufu 273165, China
- Key
Laboratory of Coastal Environmental Processes and Ecological Remediation,
Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
| | - Rui Ren
- Shandong
Province Key Laboratory of Detection Technology for Tumor Makers,
College of Chemistry and Chemical Engineering, Linyi University, Linyi 276005, China
| | - Yuxia Liu
- The
Key Laboratory of Life-Organic Analysis; Key Laboratory of Pharmaceutical
Intermediates and Analysis of Natural Medicine, College of Chemistry
and Chemical Engineering, Qufu Normal University, Qufu 273165, China
| | - Ziping Cao
- The
Key Laboratory of Life-Organic Analysis; Key Laboratory of Pharmaceutical
Intermediates and Analysis of Natural Medicine, College of Chemistry
and Chemical Engineering, Qufu Normal University, Qufu 273165, China
| | - Guoliang Li
- The
Key Laboratory of Life-Organic Analysis; Key Laboratory of Pharmaceutical
Intermediates and Analysis of Natural Medicine, College of Chemistry
and Chemical Engineering, Qufu Normal University, Qufu 273165, China
| | - Xianen Zhao
- The
Key Laboratory of Life-Organic Analysis; Key Laboratory of Pharmaceutical
Intermediates and Analysis of Natural Medicine, College of Chemistry
and Chemical Engineering, Qufu Normal University, Qufu 273165, China
| | - Lingxin Chen
- The
Key Laboratory of Life-Organic Analysis; Key Laboratory of Pharmaceutical
Intermediates and Analysis of Natural Medicine, College of Chemistry
and Chemical Engineering, Qufu Normal University, Qufu 273165, China
- Key
Laboratory of Coastal Environmental Processes and Ecological Remediation,
Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
| | - Hua Wang
- The
Key Laboratory of Life-Organic Analysis; Key Laboratory of Pharmaceutical
Intermediates and Analysis of Natural Medicine, College of Chemistry
and Chemical Engineering, Qufu Normal University, Qufu 273165, China
| | - Jinmao You
- The
Key Laboratory of Life-Organic Analysis; Key Laboratory of Pharmaceutical
Intermediates and Analysis of Natural Medicine, College of Chemistry
and Chemical Engineering, Qufu Normal University, Qufu 273165, China
- Key
Laboratory of Coastal Environmental Processes and Ecological Remediation,
Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China
| |
Collapse
|
14
|
Jun YW, Park H, Lee YK, Kaang BK, Lee JA, Jang DJ. D-AKAP1a is a signal-anchored protein in the mitochondrial outer membrane. FEBS Lett 2016; 590:954-61. [PMID: 26950402 DOI: 10.1002/1873-3468.12123] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Accepted: 03/03/2016] [Indexed: 11/08/2022]
Abstract
Dual A-kinase anchoring protein 1a (D-AKAP1a, AKAP1) regulates cAMP signaling in mitochondria. However, it is not clear how D-AKAP1a is associated with mitochondria. In this study, we show that D-AKAP1a is a transmembrane protein in the mitochondrial outer membrane (MOM). We revealed that the N-terminus of D-AKAP1a is exposed to the intermembrane space of mitochondria and that its C-terminus is located on the cytoplasmic side of the MOM. Moderate hydrophobicity and the positively charged flanking residues of the transmembrane domain of D-AKAP1a were important for targeting. Taken together, D-AKAP1a can be classified as a signal-anchored protein in the MOM. Our topological study provides valuable information about the molecular and cellular mechanisms of mitochondrial targeting of AKAP1.
Collapse
Affiliation(s)
- Yong-Woo Jun
- Department of Ecological Science, College of Ecology and Environment, Kyungpook National University, Sangju-si, Gyeongsangbuk-do, Korea
| | - Heeju Park
- Department of Applied Biology, College of Ecology and Environment, Kyungpook National University, Sangju-si, Gyeongsangbuk-do, Korea
| | - You-Kyung Lee
- Department of Biological Science and Biotechnology, College of Life Science and Nano Technology, Hannam University, Yuseong-gu, Daejeon, Korea
| | - Bong-Kiun Kaang
- Department of Biological Sciences, College of Natural Sciences, Seoul National University, Gwanak-gu, Seoul, Korea
| | - Jin-A Lee
- Department of Biological Science and Biotechnology, College of Life Science and Nano Technology, Hannam University, Yuseong-gu, Daejeon, Korea
| | - Deok-Jin Jang
- Department of Ecological Science, College of Ecology and Environment, Kyungpook National University, Sangju-si, Gyeongsangbuk-do, Korea.,Department of Applied Biology, College of Ecology and Environment, Kyungpook National University, Sangju-si, Gyeongsangbuk-do, Korea
| |
Collapse
|
15
|
Czachor A, Failla A, Lockey R, Kolliputi N. Pivotal role of AKAP121 in mitochondrial physiology. Am J Physiol Cell Physiol 2016; 310:C625-8. [PMID: 26825124 DOI: 10.1152/ajpcell.00292.2015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 01/24/2016] [Indexed: 11/22/2022]
Abstract
In this Perspective, we discuss some recent developments in the study of the mitochondrial scaffolding protein AKAP121 (also known as AKAP1, or AKAP149 as the human homolog), with an emphasis on its role in mitochondrial physiology. AKAP121 has been identified to function as a key regulatory molecule in several mitochondrial events including oxidative phosphorylation, the control of membrane potential, fission-induced apoptosis, maintenance of mitochondrial Ca(2+)homeostasis, and the phosphorylation of various mitochondrial respiratory chain substrate molecules. Furthermore, we discuss the role of hypoxia in prompting cellular stress and damage, which has been demonstrated to mediate the proteosomal degradation of AKAP121, leading to an increase in reactive oxgyen species production, mitochondrial dysfunction, and ultimately cell death.
Collapse
Affiliation(s)
- Alexander Czachor
- Division of Allergy and Immunology, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Athena Failla
- Division of Allergy and Immunology, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Richard Lockey
- Division of Allergy and Immunology, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida
| | - Narasaiah Kolliputi
- Division of Allergy and Immunology, Department of Internal Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida
| |
Collapse
|
16
|
Ferré CA, Davezac N, Thouard A, Peyrin JM, Belenguer P, Miquel MC, Gonzalez-Dunia D, Szelechowski M. Manipulation of the N-terminal sequence of the Borna disease virus X protein improves its mitochondrial targeting and neuroprotective potential. FASEB J 2015; 30:1523-33. [PMID: 26700735 DOI: 10.1096/fj.15-279620] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 12/08/2015] [Indexed: 01/11/2023]
Abstract
To favor their replication, viruses express proteins that target diverse mammalian cellular pathways. Due to the limited size of many viral genomes, such proteins are endowed with multiple functions, which require targeting to different subcellular compartments. One salient example is the X protein of Borna disease virus, which is expressed both at the mitochondria and in the nucleus. Moreover, we recently demonstrated that mitochondrial X protein is neuroprotective. In this study, we sought to examine the mechanisms whereby the X protein transits between subcellular compartments and to define its localization signals, to enhance its mitochondrial accumulation and thus, potentially, its neuroprotective activity. We transfected plasmids expressing fusion proteins bearing different domains of X fused to enhanced green fluorescent protein (eGFP) and compared their subcellular localization to that of eGFP. We observed that the 5-16 domain of X was responsible for both nuclear export and mitochondrial targeting and identified critical residues for mitochondrial localization. We next took advantage of these findings and constructed mutant X proteins that were targeted only to the mitochondria. Such mutants exhibited enhanced neuroprotective properties in compartmented cultures of neurons grown in microfluidic chambers, thereby confirming the parallel between mitochondrial accumulation of the X protein and its neuroprotective potential.-Ferré C. A., Davezac, N., Thouard, A., Peyrin, J. M., Belenguer, P., Miquel, M.-C., Gonzalez-Dunia, D., Szelechowski, M. Manipulation of the N-terminal sequence of the Borna disease virus X protein improves its mitochondrial targeting and neuroprotective potential.
Collapse
Affiliation(s)
- Cécile A Ferré
- *INSERM, Unité Mixte de Recherche (UMR) 1043, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, France; Centre National de la Recherche Scientifique (CNRS), UMR 5282, Toulouse, France; Université Toulouse III Paul Sabatier, Toulouse, France; CNRS UMR 5547, Centre de Biologie du Développement, Toulouse, France; CNRS UMR 8256, Biological Adaptation and Aging, Institut de Biologie Paris Seine, Université Pierre et Marie Curie, Paris, France; and Université Pierre et Marie Curie, Sorbonne Universités, Paris, France
| | - Noélie Davezac
- *INSERM, Unité Mixte de Recherche (UMR) 1043, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, France; Centre National de la Recherche Scientifique (CNRS), UMR 5282, Toulouse, France; Université Toulouse III Paul Sabatier, Toulouse, France; CNRS UMR 5547, Centre de Biologie du Développement, Toulouse, France; CNRS UMR 8256, Biological Adaptation and Aging, Institut de Biologie Paris Seine, Université Pierre et Marie Curie, Paris, France; and Université Pierre et Marie Curie, Sorbonne Universités, Paris, France
| | - Anne Thouard
- *INSERM, Unité Mixte de Recherche (UMR) 1043, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, France; Centre National de la Recherche Scientifique (CNRS), UMR 5282, Toulouse, France; Université Toulouse III Paul Sabatier, Toulouse, France; CNRS UMR 5547, Centre de Biologie du Développement, Toulouse, France; CNRS UMR 8256, Biological Adaptation and Aging, Institut de Biologie Paris Seine, Université Pierre et Marie Curie, Paris, France; and Université Pierre et Marie Curie, Sorbonne Universités, Paris, France
| | - Jean-Michel Peyrin
- *INSERM, Unité Mixte de Recherche (UMR) 1043, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, France; Centre National de la Recherche Scientifique (CNRS), UMR 5282, Toulouse, France; Université Toulouse III Paul Sabatier, Toulouse, France; CNRS UMR 5547, Centre de Biologie du Développement, Toulouse, France; CNRS UMR 8256, Biological Adaptation and Aging, Institut de Biologie Paris Seine, Université Pierre et Marie Curie, Paris, France; and Université Pierre et Marie Curie, Sorbonne Universités, Paris, France
| | - Pascale Belenguer
- *INSERM, Unité Mixte de Recherche (UMR) 1043, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, France; Centre National de la Recherche Scientifique (CNRS), UMR 5282, Toulouse, France; Université Toulouse III Paul Sabatier, Toulouse, France; CNRS UMR 5547, Centre de Biologie du Développement, Toulouse, France; CNRS UMR 8256, Biological Adaptation and Aging, Institut de Biologie Paris Seine, Université Pierre et Marie Curie, Paris, France; and Université Pierre et Marie Curie, Sorbonne Universités, Paris, France
| | - Marie-Christine Miquel
- *INSERM, Unité Mixte de Recherche (UMR) 1043, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, France; Centre National de la Recherche Scientifique (CNRS), UMR 5282, Toulouse, France; Université Toulouse III Paul Sabatier, Toulouse, France; CNRS UMR 5547, Centre de Biologie du Développement, Toulouse, France; CNRS UMR 8256, Biological Adaptation and Aging, Institut de Biologie Paris Seine, Université Pierre et Marie Curie, Paris, France; and Université Pierre et Marie Curie, Sorbonne Universités, Paris, France
| | - Daniel Gonzalez-Dunia
- *INSERM, Unité Mixte de Recherche (UMR) 1043, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, France; Centre National de la Recherche Scientifique (CNRS), UMR 5282, Toulouse, France; Université Toulouse III Paul Sabatier, Toulouse, France; CNRS UMR 5547, Centre de Biologie du Développement, Toulouse, France; CNRS UMR 8256, Biological Adaptation and Aging, Institut de Biologie Paris Seine, Université Pierre et Marie Curie, Paris, France; and Université Pierre et Marie Curie, Sorbonne Universités, Paris, France
| | - Marion Szelechowski
- *INSERM, Unité Mixte de Recherche (UMR) 1043, Centre de Physiopathologie de Toulouse Purpan (CPTP), Toulouse, France; Centre National de la Recherche Scientifique (CNRS), UMR 5282, Toulouse, France; Université Toulouse III Paul Sabatier, Toulouse, France; CNRS UMR 5547, Centre de Biologie du Développement, Toulouse, France; CNRS UMR 8256, Biological Adaptation and Aging, Institut de Biologie Paris Seine, Université Pierre et Marie Curie, Paris, France; and Université Pierre et Marie Curie, Sorbonne Universités, Paris, France
| |
Collapse
|
17
|
Jun YW, Lee JA, Jang DJ. Development of intracellular organelle markers using modified glycolipid-binding peptides in mammalian cells. ANALYTICAL SCIENCE AND TECHNOLOGY 2015. [DOI: 10.5806/ast.2015.28.1.65] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
18
|
Mehta S, Aye-Han NN, Ganesan A, Oldach L, Gorshkov K, Zhang J. Calmodulin-controlled spatial decoding of oscillatory Ca2+ signals by calcineurin. eLife 2014; 3:e03765. [PMID: 25056880 PMCID: PMC4141273 DOI: 10.7554/elife.03765] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Calcineurin is responsible for mediating a wide variety of cellular processes in response to dynamic calcium (Ca(2+)) signals, yet the precise mechanisms involved in the spatiotemporal control of calcineurin signaling are poorly understood. Here, we use genetically encoded fluorescent biosensors to directly probe the role of cytosolic Ca(2+) oscillations in modulating calcineurin activity dynamics in insulin-secreting MIN6 β-cells. We show that Ca(2+) oscillations induce distinct temporal patterns of calcineurin activity in the cytosol and plasma membrane vs at the ER and mitochondria in these cells. Furthermore, we found that these differential calcineurin activity patterns are determined by variations in the subcellular distribution of calmodulin (CaM), indicating that CaM plays an active role in shaping both the spatial and temporal aspects of calcineurin signaling. Together, our findings provide new insights into the mechanisms by which oscillatory signals are decoded to generate specific functional outputs within different cellular compartments.
Collapse
Affiliation(s)
- Sohum Mehta
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, United States
| | - Nwe-Nwe Aye-Han
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, United States
| | - Ambhighainath Ganesan
- Department of Biomedical Engineering, The Johns Hopkins University, Baltimore, United States
| | - Laurel Oldach
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, United States
| | - Kirill Gorshkov
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, United States
| | - Jin Zhang
- Department of Pharmacology and Molecular Sciences, The Johns Hopkins University School of Medicine, Baltimore, United States The Solomon H. Snyder Department of Neuroscience, The Johns Hopkins University School of Medicine, Baltimore, United States Department of Oncology, The Johns Hopkins University School of Medicine, Baltimore, United States
| |
Collapse
|
19
|
Mason TA, Goldenring JR, Kolobova E. AKAP350C targets to mitochondria via a novel amphipathic alpha helical domain. CELLULAR LOGISTICS 2014; 4:e943597. [PMID: 25610720 DOI: 10.4161/21592780.2014.943597] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 06/24/2014] [Indexed: 02/01/2023]
Abstract
Mitochondria regulate metabolism and homeostasis within cells. Mitochondria are also very dynamic organelles, constantly undergoing fission and fusion. The importance of maintaining proper mitochondrial dynamics is evident in the various diseases associated with defects in these processes. Protein kinase A (PKA) is a key regulator of mitochondrial dynamics. PKA is spatially regulated by A-Kinase Anchoring Proteins (AKAPs). We completed cloning of a novel AKAP350 isoform, AKAP350C. Immunostaining for endogenous AKAP350C showed localization to mitochondria. The carboxyl-terminal 54-amino acid sequence unique to AKAP350C contains a novel amphipathic alpha helical mitochondrial-targeting domain. AKAP350C co-localizes with Mff (mitochondrial fission protein) and mitofusins 1 and 2 (mitochondrial fusion proteins), and likely regulates mitochondrial dynamics by scaffolding PKA and mitochondrial fission and fusion proteins.
Collapse
Affiliation(s)
- Twila A Mason
- Departments of Cell and Developmental Biology; Vanderbilt University Medical Center ; Nashville, TN USA ; Epithelial Biology Center; Vanderbilt University Medical Center ; Nashville, TN USA
| | - James R Goldenring
- Departments of Cell and Developmental Biology; Vanderbilt University Medical Center ; Nashville, TN USA ; Epithelial Biology Center; Vanderbilt University Medical Center ; Nashville, TN USA ; Department of Surgery; Vanderbilt University Medical Center ; Nashville, TN USA ; Nashville Department of Veterans Affairs Medical Center ; Nashville, TN USA
| | - Elena Kolobova
- Epithelial Biology Center; Vanderbilt University Medical Center ; Nashville, TN USA ; Department of Surgery; Vanderbilt University Medical Center ; Nashville, TN USA
| |
Collapse
|
20
|
Merrill RA, Strack S. Mitochondria: a kinase anchoring protein 1, a signaling platform for mitochondrial form and function. Int J Biochem Cell Biol 2014; 48:92-6. [PMID: 24412345 DOI: 10.1016/j.biocel.2013.12.012] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 11/28/2013] [Accepted: 12/26/2013] [Indexed: 12/31/2022]
Abstract
Mitochondria are best known for their role as cellular power plants, but they also serve as signaling hubs, regulating cellular proliferation, differentiation, and survival. A kinase anchoring protein 1 (AKAP1) is a scaffold protein that recruits protein kinase A (PKA) and other signaling proteins, as well as RNA, to the outer mitochondrial membrane. AKAP1 thereby integrates several second messenger cascades to modulate mitochondrial function and associated physiological and pathophysiological outcomes. Here, we review what is currently known about AKAP1's macromolecular interactions in health and disease states, including obesity. We also discuss dynamin-related protein 1 (Drp1), the enzyme that catalyzes mitochondrial fission, as one of the key substrates of the PKA/AKAP1 signaling complex in neurons. Recent evidence suggests that AKAP1 has critical roles in neuronal development and survival, which are mediated by inhibitory phosphorylation of Drp1 and maintenance of mitochondrial integrity.
Collapse
Affiliation(s)
| | - Stefan Strack
- Department of Pharmacology, University of Iowa, Iowa City, USA.
| |
Collapse
|
21
|
Cazabat L, Ragazzon B, Varin A, Potier-Cartereau M, Vandier C, Vezzosi D, Risk-Rabin M, Guellich A, Schittl J, Lechêne P, Richter W, Nikolaev VO, Zhang J, Bertherat J, Vandecasteele G. Inactivation of the Carney complex gene 1 (PRKAR1A) alters spatiotemporal regulation of cAMP and cAMP-dependent protein kinase: a study using genetically encoded FRET-based reporters. Hum Mol Genet 2013; 23:1163-74. [PMID: 24122441 DOI: 10.1093/hmg/ddt510] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Carney complex (CNC) is a hereditary disease associating cardiac myxoma, spotty skin pigmentation and endocrine overactivity. CNC is caused by inactivating mutations in the PRKAR1A gene encoding PKA type I alpha regulatory subunit (RIα). Although PKA activity is enhanced in CNC, the mechanisms linking PKA dysregulation to endocrine tumorigenesis are poorly understood. In this study, we used Förster resonance energy transfer (FRET)-based sensors for cAMP and PKA activity to define the role of RIα in the spatiotemporal organization of the cAMP/PKA pathway. RIα knockdown in HEK293 cells increased basal as well as forskolin or prostaglandin E1 (PGE1)-stimulated total cellular PKA activity as reported by western blots of endogenous PKA targets and the FRET-based global PKA activity reporter, AKAR3. Using variants of AKAR3 targeted to subcellular compartments, we identified similar increases in the response to PGE1 in the cytoplasm and at the outer mitochondrial membrane. In contrast, at the plasma membrane, the response to PGE1 was decreased along with an increase in basal FRET ratio. These results were confirmed by western blot analysis of basal and PGE1-induced phosphorylation of membrane-associated vasodilator-stimulated phosphoprotein. Similar differences were observed between the cytoplasm and the plasma membrane in human adrenal cells carrying a RIα inactivating mutation. RIα inactivation also increased cAMP in the cytoplasm, at the outer mitochondrial membrane and at the plasma membrane, as reported by targeted versions of the cAMP indicator Epac1-camps. These results show that RIα inactivation leads to multiple, compartment-specific alterations of the cAMP/PKA pathway revealing new aspects of signaling dysregulation in tumorigenesis.
Collapse
|
22
|
Grozdanov PN, Stocco DM. Short RNA molecules with high binding affinity to the KH motif of A-kinase anchoring protein 1 (AKAP1): implications for the regulation of steroidogenesis. Mol Endocrinol 2012; 26:2104-17. [PMID: 23077346 DOI: 10.1210/me.2012-1123] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
One of the key regulators of acute steroid hormone biosynthesis in steroidogenic tissues is the steroidogenic acute regulatory (STAR) protein. Acute regulation of STAR production on the transcriptional level is mainly achieved through a cAMP-dependent mechanism, which is well understood. However, less is known about the posttranscriptional regulation of STAR synthesis, specifically the factors influencing the destiny of the Star mRNA after it leaves the nucleus. Here, we show that the 3'-untranslated region of Star mRNA interacts with the heterogeneous nuclear ribonucleoprotein K-homology (KH) motif of the mitochondrial scaffold A-kinase anchoring protein 1 (AKAP1) in vitro with a moderate affinity as measured by EMSAs. A mutation that mimics the phosphorylation state of the KH motif at a specific serine either did not alter, or had a negative impact on, protein-RNA binding under these conditions. The KH motif of AKAP1 binds short pyrimidine-rich RNA molecules with a stable hairpin structure as demonstrated by in vitro selection. AKAP1 also interacts with STAR mRNA in a dibutyryl-cAMP-stimulated human steroidogenic adrenocortical carcinoma cell line in vivo. Therefore, we propose a model in which AKAP1 anchors Star mRNA at the mitochondria, thus stabilizing the translational complex at this organelle, a situation that might affect STAR production and steroidogenesis. In addition, we suggest that the last 216 amino acid residues of AKAP1 might participate in the degradation of STAR and other nuclear-encoded mitochondrial mRNAs through interaction with a RNA-induced silencing complex, specifically with the argonaute 2 protein.
Collapse
Affiliation(s)
- Petar N Grozdanov
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA
| | | |
Collapse
|
23
|
Tröger J, Moutty MC, Skroblin P, Klussmann E. A-kinase anchoring proteins as potential drug targets. Br J Pharmacol 2012; 166:420-33. [PMID: 22122509 DOI: 10.1111/j.1476-5381.2011.01796.x] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
A-kinase anchoring proteins (AKAPs) crucially contribute to the spatial and temporal control of cellular signalling. They directly interact with a variety of protein binding partners and cellular constituents, thereby directing pools of signalling components to defined locales. In particular, AKAPs mediate compartmentalization of cAMP signalling. Alterations in AKAP expression and their interactions are associated with or cause diseases including chronic heart failure, various cancers and disorders of the immune system such as HIV. A number of cellular dysfunctions result from mutations of specific AKAPs. The link between malfunctions of single AKAP complexes and a disease makes AKAPs and their interactions interesting targets for the development of novel drugs. LINKED ARTICLES This article is part of a themed section on Novel cAMP Signalling Paradigms. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.166.issue-2.
Collapse
Affiliation(s)
- Jessica Tröger
- Max Delbrück Center for Molecular Medicine Berlin-Buch (MDC), Berlin, Germany Leibniz Institute for Molecular Pharmacology (FMP), Berlin, Germany
| | | | | | | |
Collapse
|
24
|
Cell signaling and mitochondrial dynamics: Implications for neuronal function and neurodegenerative disease. Neurobiol Dis 2012; 51:13-26. [PMID: 22297163 DOI: 10.1016/j.nbd.2012.01.009] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2011] [Revised: 01/09/2012] [Accepted: 01/12/2012] [Indexed: 11/22/2022] Open
Abstract
Nascent evidence indicates that mitochondrial fission, fusion, and transport are subject to intricate regulatory mechanisms that intersect with both well-characterized and emerging signaling pathways. While it is well established that mutations in components of the mitochondrial fission/fusion machinery can cause neurological disorders, relatively little is known about upstream regulators of mitochondrial dynamics and their role in neurodegeneration. Here, we review posttranslational regulation of mitochondrial fission/fusion enzymes, with particular emphasis on dynamin-related protein 1 (Drp1), as well as outer mitochondrial signaling complexes involving protein kinases and phosphatases. We also review recent evidence that mitochondrial dynamics has profound consequences for neuronal development and synaptic transmission and discuss implications for clinical translation.
Collapse
|
25
|
Kim H, Scimia MC, Wilkinson D, Trelles RD, Wood MR, Bowtell D, Dillin A, Mercola M, Ronai ZA. Fine-tuning of Drp1/Fis1 availability by AKAP121/Siah2 regulates mitochondrial adaptation to hypoxia. Mol Cell 2012; 44:532-44. [PMID: 22099302 DOI: 10.1016/j.molcel.2011.08.045] [Citation(s) in RCA: 180] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 06/24/2011] [Accepted: 08/12/2011] [Indexed: 11/28/2022]
Abstract
Defining the mechanisms underlying the control of mitochondrial fusion and fission is critical to understanding cellular adaptation to diverse physiological conditions. Here we demonstrate that hypoxia induces fission of mitochondrial membranes, dependent on availability of the mitochondrial scaffolding protein AKAP121. AKAP121 controls mitochondria dynamics through PKA-dependent inhibitory phosphorylation of Drp1 and PKA-independent inhibition of Drp1-Fis1 interaction. Reduced availability of AKAP121 by the ubiquitin ligase Siah2 relieves Drp1 inhibition by PKA and increases its interaction with Fis1, resulting in mitochondrial fission. High AKAP121 levels, seen in cells lacking Siah2, attenuate fission and reduce apoptosis of cardiomyocytes under simulated ischemia. Infarct size and degree of cell death were reduced in Siah2(-/-) mice subjected to myocardial infarction. Inhibition of Siah2 or Drp1 in hatching C. elegans reduces their life span. Through modulating Fis1/Drp1 complex availability, our studies identify Siah2 as a key regulator of hypoxia-induced mitochondrial fission and its physiological significance in ischemic injury and nematode life span.
Collapse
Affiliation(s)
- Hyungsoo Kim
- Signal Transduction Program, Sanford-Burnham Medical Research Institute, La Jolla, CA 92037, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
26
|
Abstract
To identify candidate proteins in the nucleus accumbens (NAc) as potential pharmacotherapeutic targets for treating cocaine addition, an 8-plex iTRAQ (isobaric tag for relative and absolute quantitation) proteomic screen was performed using NAc tissue obtained from rats trained to self-administer cocaine followed by extinction training. Compared with yoked-saline controls, 42 proteins in a postsynaptic density (PSD)-enriched subfraction of the NAc from cocaine-trained animals were identified as significantly changed. Among proteins of interest whose levels were identified as increased was AKAP79/150, the rat ortholog of human AKAP5, a PSD scaffolding protein that localizes signaling molecules to the synapse. Functional downregulation of AKAP79/150 by microinjecting a cell-permeable synthetic AKAP (A-kinase anchor protein) peptide into the NAc to disrupt AKAP-dependent signaling revealed that inhibition of AKAP signaling impaired the reinstatement of cocaine seeking. Reinstatement of cocaine seeking is thought to require upregulated surface expression of AMPA glutamate receptors, and the inhibitory AKAP peptide reduced the PSD content of protein kinase A (PKA) as well as surface expression of GluR1 in NAc. However, reduced surface expression was not associated with changes in PKA phosphorylation of GluR1. This series of experiments demonstrates that proteomic analysis provides a useful tool for identifying proteins that can regulate cocaine relapse and that AKAP proteins may contribute to relapse vulnerability by promoting increased surface expression of AMPA receptors in the NAc.
Collapse
|
27
|
Mechanism of neuroprotective mitochondrial remodeling by PKA/AKAP1. PLoS Biol 2011; 9:e1000612. [PMID: 21526220 PMCID: PMC3079583 DOI: 10.1371/journal.pbio.1000612] [Citation(s) in RCA: 151] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2010] [Accepted: 03/10/2011] [Indexed: 11/29/2022] Open
Abstract
The mitochondrial signaling complex PKA/AKAP1 protects neurons against
mitochondrial fragmentation and cell death by phosphorylating and inactivating
the mitochondrial fission enzyme Drp1. Mitochondrial shape is determined by fission and fusion reactions catalyzed by
large GTPases of the dynamin family, mutation of which can cause neurological
dysfunction. While fission-inducing protein phosphatases have been identified,
the identity of opposing kinase signaling complexes has remained elusive. We
report here that in both neurons and non-neuronal cells, cAMP elevation and
expression of an outer-mitochondrial membrane (OMM) targeted form of the protein
kinase A (PKA) catalytic subunit reshapes mitochondria into an interconnected
network. Conversely, OMM-targeting of the PKA inhibitor PKI promotes
mitochondrial fragmentation upstream of neuronal death. RNAi and overexpression
approaches identify mitochondria-localized A kinase anchoring protein 1 (AKAP1)
as a neuroprotective and mitochondria-stabilizing factor in vitro and in vivo.
According to epistasis studies with phosphorylation site-mutant dynamin-related
protein 1 (Drp1), inhibition of the mitochondrial fission enzyme through a
conserved PKA site is the principal mechanism by which cAMP and PKA/AKAP1
promote both mitochondrial elongation and neuronal survival. Phenocopied by a
mutation that slows GTP hydrolysis, Drp1 phosphorylation inhibits the
disassembly step of its catalytic cycle, accumulating large, slowly recycling
Drp1 oligomers at the OMM. Unopposed fusion then promotes formation of a
mitochondrial reticulum, which protects neurons from diverse insults. Mitochondria, the cellular powerhouse, are highly dynamic organelles shaped by
opposing fission and fusion events. Research over the past decade has identified
many components of the mitochondrial fission/fusion machinery and led to the
discovery that mutations in genes coding for these proteins can cause human
neurological diseases. While it is well established that mitochondrial shape
changes are intimately involved in cellular responses to environmental
stressors, we know very little about the mechanisms by which cells dynamically
adjust mitochondrial form and function. In this report, we show that the
scaffold protein AKAP1 brings the cAMP-dependent protein kinase PKA to the outer
mitochondrial membrane to protect neurons from injury. The PKA/AKAP1 complex
functions by inhibiting Drp1, an enzyme that mechanically constricts and
eventually severs mitochondria. Whereas active, dephosphorylated Drp1 rapidly
cycles between cytosol and mitochondria, phosphorylated Drp1 builds up in
inactive mitochondrial complexes, allowing mitochondria to fuse into a
neuroprotective reticulum. Our results suggest that altering the balance of
kinase and phosphatase activities at the outer mitochondrial membrane may
provide the basis for novel neuroprotective therapies.
Collapse
|
28
|
Vanhee C, Guillon S, Masquelier D, Degand H, Deleu M, Morsomme P, Batoko H. A TSPO-related protein localizes to the early secretory pathway in Arabidopsis, but is targeted to mitochondria when expressed in yeast. JOURNAL OF EXPERIMENTAL BOTANY 2011; 62:497-508. [PMID: 20847098 PMCID: PMC3003801 DOI: 10.1093/jxb/erq283] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2010] [Revised: 08/16/2010] [Accepted: 08/19/2010] [Indexed: 05/29/2023]
Abstract
AtTSPO is a TspO/MBR domain-protein potentially involved in multiple stress regulation in Arabidopsis. As in most angiosperms, AtTSPO is encoded by a single, intronless gene. Expression of AtTSPO is tightly regulated both at the transcriptional and post-translational levels. It has been shown previously that overexpression of AtTSPO in plant cell can be detrimental, and the protein was detected in the endoplasmic reticulum (ER) and Golgi stacks, contrasting with previous findings and suggesting a mitochondrial subcellular localization for this protein. To ascertain these findings, immunocytochemistry and ABA induction were used to demonstrate that, in plant cells, physiological levels of AtTSPO colocalized with AtArf1, a mainly Golgi-localized protein in plant cells. In addition, fluorescent protein-tagged AtTSPO was targeted to the secretory pathway and did not colocalize with MitoTracker-labelled mitochondria. These results suggest that the polytopic membrane protein AtTSPO is cotranslationally targeted to the ER in plant cells and accumulates in the Trans-Golgi Network. Heterologous expression of AtTSPO in Saccharomyces cerevisiae, yeast devoid of TSPO-related protein, resulted in growth defects. However, subcellular fractionation and immunoprecipitation experiments showed that AtTSPO was targeted to mitochondria where it colocalized and interacted with the outer mitochondrial membrane porin VDAC1p, reminiscent of the subcellular localization and activity of mammalian translocator protein 18 kDa TSPO. The evolutionarily divergent AtTSPO appears therefore to be switching its sorting mode in a species-dependent manner, an uncommon peculiarity for a polytopic membrane protein in eukaryotic cells. These results are discussed in relation to the recognition and organelle targeting mechanisms of polytopic membrane proteins in eukaryotic cells.
Collapse
Affiliation(s)
- Celine Vanhee
- Institut des Sciences de la Vie (ISV), Molecular Physiology Group (FYMO), Université catholique de Louvain, Croix du Sud 4-15, 1348 Louvain-la-Neuve, Belgium
| | - Stéphanie Guillon
- Institut des Sciences de la Vie (ISV), Molecular Physiology Group (FYMO), Université catholique de Louvain, Croix du Sud 4-15, 1348 Louvain-la-Neuve, Belgium
| | - Danièle Masquelier
- Institut des Sciences de la Vie (ISV), Molecular Physiology Group (FYMO), Université catholique de Louvain, Croix du Sud 4-15, 1348 Louvain-la-Neuve, Belgium
| | - Hervé Degand
- Institut des Sciences de la Vie (ISV), Molecular Physiology Group (FYMO), Université catholique de Louvain, Croix du Sud 4-15, 1348 Louvain-la-Neuve, Belgium
| | - Magali Deleu
- Unité de Chimie Biologique Industrielle, Université de Liège, Gembloux Agro-BioTech (GxABT), Passage des Déportés 2, 5030 Gembloux, Belgium
| | - Pierre Morsomme
- Institut des Sciences de la Vie (ISV), Molecular Physiology Group (FYMO), Université catholique de Louvain, Croix du Sud 4-15, 1348 Louvain-la-Neuve, Belgium
| | - Henri Batoko
- Institut des Sciences de la Vie (ISV), Molecular Physiology Group (FYMO), Université catholique de Louvain, Croix du Sud 4-15, 1348 Louvain-la-Neuve, Belgium
| |
Collapse
|
29
|
Agnes RS, Jernigan F, Shell JR, Sharma V, Lawrence DS. Suborganelle sensing of mitochondrial cAMP-dependent protein kinase activity. J Am Chem Soc 2010; 132:6075-80. [PMID: 20380406 DOI: 10.1021/ja909652q] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A fluorescent sensor of protein kinase activity has been developed and used to characterize the compartmentalized location of cAMP-dependent protein kinase activity in mitochondria. The sensor functions via a phosphorylation-induced release of a quencher from a peptide-based substrate, producing a 150-fold enhancement in fluorescence. The quenching phenomenon transpires via interaction of the quencher with Arg residues positioned on the peptide substrate. Although the cAMP-dependent protein kinase is known to be present in mitochondria, the relative amount of enzyme positioned in the major compartments (outer membrane, intermembrane space, and the matrix) of the organelle is unclear. The fluorescent sensor developed in this study was used to reveal the relative matrix/intermembrane space/outer membrane (85:6:9) distribution of PKA in bovine heart mitochondria.
Collapse
Affiliation(s)
- Richard S Agnes
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA
| | | | | | | | | |
Collapse
|
30
|
Organic cation/carnitine transporter OCTN3 is present in astrocytes and is up-regulated by peroxisome proliferators-activator receptor agonist. Int J Biochem Cell Biol 2009; 41:2599-609. [DOI: 10.1016/j.biocel.2009.08.020] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2009] [Revised: 08/26/2009] [Accepted: 08/30/2009] [Indexed: 11/18/2022]
|
31
|
Anandatheerthavarada HK, Sepuri NBV, Avadhani NG. Mitochondrial targeting of cytochrome P450 proteins containing NH2-terminal chimeric signals involves an unusual TOM20/TOM22 bypass mechanism. J Biol Chem 2009; 284:17352-17363. [PMID: 19401463 DOI: 10.1074/jbc.m109.007492] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previously we showed that xenobiotic inducible cytochrome P450 (CYP) proteins are bimodally targeted to the endoplasmic reticulum and mitochondria. In this study, we investigated the mechanism of delivery of chimeric signal containing CYP proteins to the peripheral and channel-forming mitochondrial outer membrane translocases (TOMs). CYP+33/1A1 and CYP2B1 did not require peripheral TOM70, TOM20, or TOM22 for translocation through the channel-forming TOM40 protein. In contrast, CYP+5/1A1 and CYP2E1 were able to bypass TOM20 and TOM22 but required TOM70. CYP27, which contains a canonical cleavable mitochondrial signal, required all of the peripheral TOMs for its mitochondrial translocation. We investigated the underlying mechanisms of bypass of peripheral TOMs by CYPs with chimeric signals. The results suggested that interaction of CYPs with Hsp70, a cytosolic chaperone involved in the mitochondrial import, alone was sufficient for the recognition of chimeric signals by peripheral TOMs. However, sequential interaction of chimeric signal containing CYPs with Hsp70 and Hsp90 resulted in the bypass of peripheral TOMs, whereas CYP27A1 interacted only with Hsp70 and was not able to bypass peripheral TOMs. Our results also show that delivery of a chimeric signal containing client protein by Hsp90 required the cytosol-exposed NH(2)-terminal 143 amino acids of TOM40. TOM40 devoid of this domain was unable to import CYP proteins. These results suggest that compared with the unimodal mitochondrial targeting signals, the chimeric mitochondrial targeting signals are highly evolved and dynamic in nature.
Collapse
Affiliation(s)
- Hindupur K Anandatheerthavarada
- From the Department of Animal Biology and the Mari Lowe Center for Comparative Oncology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Naresh Babu V Sepuri
- From the Department of Animal Biology and the Mari Lowe Center for Comparative Oncology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Narayan G Avadhani
- From the Department of Animal Biology and the Mari Lowe Center for Comparative Oncology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104.
| |
Collapse
|
32
|
Chatre L, Matheson LA, Jack AS, Hanton SL, Brandizzi F. Efficient mitochondrial targeting relies on co-operation of multiple protein signals in plants. JOURNAL OF EXPERIMENTAL BOTANY 2008; 60:741-9. [PMID: 19112171 PMCID: PMC2652046 DOI: 10.1093/jxb/ern319] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2008] [Revised: 10/06/2008] [Accepted: 11/18/2008] [Indexed: 05/24/2023]
Abstract
To date, the most prevalent model for transport of pre-proteins to plant mitochondria is based on the activity of an N-terminal extension serving as a targeting peptide. Whether the efficient delivery of proteins to mitochondria is based exclusively on the action of the N-terminal extension or also on that of other protein determinants has yet to be defined. A novel mechanism is reported here for the targeting of a plant protein, named MITS1, to mitochondria. It was found that MITS1 contains an N-terminal extension that is responsible for mitochondrial targeting. Functional dissection of this extension shows the existence of a cryptic signal for protein targeting to the secretory pathway. The first 11 amino acids of the N-terminal extension are necessary to overcome the activity of this signal sequence and target the protein to the mitochondria. These data suggest that co-operation of multiple determinants within the N-terminal extension of mitochondrial proteins may be necessary for efficient mitochondrial targeting. It was also established that the presence of a tryptophan residue toward the C-terminus of the protein is crucial for mitochondrial targeting, as mutation of this residue results in a redistribution of MITS1 to the endoplasmic reticulum and Golgi apparatus. These data suggest a novel targeting model whereby protein traffic to plant mitochondria is influenced by domains in the full-length protein as well as the N-terminal extension.
Collapse
Affiliation(s)
- Laurent Chatre
- Department of Biology, 112 Science Place, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
| | - Loren A. Matheson
- Department of Biology, 112 Science Place, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
| | - Andrew S. Jack
- Department of Biology, 112 Science Place, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
| | - Sally L. Hanton
- Department of Biology, 112 Science Place, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
| | - Federica Brandizzi
- Department of Biology, 112 Science Place, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
- Department of Energy, Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA
| |
Collapse
|
33
|
Boopathi E, Srinivasan S, Fang JK, Avadhani NG. Bimodal protein targeting through activation of cryptic mitochondrial targeting signals by an inducible cytosolic endoprotease. Mol Cell 2008; 32:32-42. [PMID: 18851831 DOI: 10.1016/j.molcel.2008.09.008] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2007] [Revised: 04/21/2008] [Accepted: 09/17/2008] [Indexed: 10/21/2022]
Abstract
Bimodal targeting of the endoplasmic reticular protein, cytochrome P4501A1 (CYP1A1), to mitochondria involves activation of a cryptic mitochondrial targeting signal through endoprotease processing of the protein. Here, we characterized the endoprotease that regulates mitochondrial targeting of CYP1A1. The endoprotease, which was induced by beta-naphthoflavone, was a dimer of 90 kDa and 40 kDa subunits, each containing Ser protease domains. The purified protease processed CYP1A1 in a sequence-specific manner, leading to its mitochondrial import. The glucocorticoid receptor, retinoid X receptor, and p53 underwent similar processing-coupled mitochondrial transport. The inducible 90 kDa subunit was a limiting factor in many cells and some tissues and, thus, regulates the mitochondrial levels of these proteins. A number of other mitochondria-associated proteins with noncanonical targeting signals may also be substrates of this endoprotease. Our results describe a new mechanism of mitochondrial protein import that requires an inducible cytoplasmic endoprotease for activation of cryptic mitochondrial targeting signals.
Collapse
Affiliation(s)
- Ettickan Boopathi
- Department of Animal Biology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | | | | |
Collapse
|
34
|
Papp LV, Wang J, Kennedy D, Boucher D, Zhang Y, Gladyshev VN, Singh RN, Khanna KK. Functional characterization of alternatively spliced human SECISBP2 transcript variants. Nucleic Acids Res 2008; 36:7192-206. [PMID: 19004874 PMCID: PMC2602786 DOI: 10.1093/nar/gkn829] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Synthesis of selenoproteins depends on decoding of the UGA stop codon as the amino acid selenocysteine (Sec). This process requires the presence of a Sec insertion sequence element (SECIS) in the 3′-untranslated region of selenoprotein mRNAs and its interaction with the SECIS binding protein 2 (SBP2). In humans, mutations in the SBP2-encoding gene Sec insertion sequence binding protein 2 (SECISBP2) that alter the amino acid sequence or cause splicing defects lead to abnormal thyroid hormone metabolism. Herein, we present the first in silico and in vivo functional characterization of alternative splicing of SECISBP2. We report a complex splicing pattern in the 5′-region of human SECISBP2, wherein at least eight splice variants encode five isoforms with varying N-terminal sequence. One of the isoforms, mtSBP2, contains a mitochondrial targeting sequence and localizes to mitochondria. Using a minigene-based in vivo splicing assay we characterized the splicing efficiency of several alternative transcripts, and show that the splicing event that creates mtSBP2 can be modulated by antisense oligonucleotides. Moreover, we show that full-length SBP2 and some alternatively spliced variants are subject to a coordinated transcriptional and translational regulation in response to ultraviolet type A irradiation-induced stress. Overall, our data broadens the functional scope of a housekeeping protein essential to selenium metabolism.
Collapse
Affiliation(s)
- Laura V Papp
- Signal Transduction Laboratory, Queensland Institute of Medical Research, Herston, Queensland, Australia.
| | | | | | | | | | | | | | | |
Collapse
|
35
|
Carlucci A, Lignitto L, Feliciello A. Control of mitochondria dynamics and oxidative metabolism by cAMP, AKAPs and the proteasome. Trends Cell Biol 2008; 18:604-13. [PMID: 18951795 DOI: 10.1016/j.tcb.2008.09.006] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2008] [Revised: 09/27/2008] [Accepted: 09/29/2008] [Indexed: 12/29/2022]
Abstract
Mitochondria are highly specialized organelles and major players in fundamental aspects of cell physiology. In yeast, energy metabolism and coupling of mitochondrial activity to growth and survival is controlled by the protein kinase A pathway. In higher eukaryotes, modulation of the so-called A-kinase anchor protein (AKAP) complex regulates mitochondrial dynamics and activity, adapting the oxidative machinery and the metabolic pathway to changes in physiological demand. Protein kinases and phosphatases are assembled by AKAPs within transduction units, providing a mechanism to control signaling events at mitochondria and other target organelles. Ubiquitin-mediated proteolysis of signal transducers and effectors provides an additional layer of complexity in the regulation of mitochondria homeostasis. Genetic evidence indicates that alteration of one or more components of these biochemical pathways leads to mitochondrial dysfunction and human diseases. In this review, we focus on the emerging role of AKAP scaffolds and the proteasome pathway in the control of oxidative metabolism, organelle dynamics and the mitochondrial signaling network. These aspects are crucial elements for maintaining a proper energy balance and cellular lifespan.
Collapse
Affiliation(s)
- Annalisa Carlucci
- Dipartimento di Biologia e Patologia Molecolare e Cellulare, Università Federico II, Naples, Italy
| | | | | |
Collapse
|
36
|
Anandatheerthavarada HK, Sepuri NBV, Biswas G, Avadhani NG. An unusual TOM20/TOM22 bypass mechanism for the mitochondrial targeting of cytochrome P450 proteins containing N-terminal chimeric signals. J Biol Chem 2008; 283:19769-80. [PMID: 18480056 DOI: 10.1074/jbc.m801464200] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Previously we showed that xenobiotic-inducible cytochrome P450 (CYP) proteins are bimodally targeted to the endoplasmic reticulum and mitochondria. In the present study, we investigated the mechanism of delivery of chimeric signal-containing CYP proteins to the peripheral and channel-forming mitochondrial outer membrane translocases (TOMs). CYP+33/1A1 and CYP2B1 did not require peripheral TOM70, TOM20, or TOM22 for translocation through the channel-forming TOM40 protein. In contrast, CYP+5/1A1 and CYP2E1 were able to bypass TOM20 and TOM22 but required TOM70. CYP27, which contains a canonical cleavable mitochondrial signal, required all of the peripheral TOMs for its mitochondrial translocation. We investigated the underlying mechanisms of bypass of peripheral TOMs by CYPs with chimeric signals. The results suggested that interaction of CYPs with Hsp70, a cytosolic chaperone involved in the mitochondrial import, alone was sufficient for the recognition of chimeric signals by peripheral TOMs. However, sequential interaction of chimeric signal-containing CYPs with Hsp70 and Hsp90 resulted in the bypass of peripheral TOMs, whereas CYP27 interacted only with Hsp70 and was not able to bypass peripheral TOMs. Our results also show that delivery of chimeric signal-containing client proteins by Hsp90 required the cytosol-exposed N-terminal 143 amino acids of TOM40. TOM40 devoid of this domain was unable to bind CYP proteins. These results suggest that, compared with the unimodal mitochondria-targeting signals, the chimeric mitochondria-targeting signals are highly evolved and dynamic in nature.
Collapse
Affiliation(s)
- Hindupur K Anandatheerthavarada
- Department of Animal Biology and the Mari Lowe Center for Comparative Oncology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | | | | | | |
Collapse
|