1
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York HM, Joshi K, Wright CS, Kreplin LZ, Rodgers SJ, Moorthi UK, Gandhi H, Patil A, Mitchell CA, Iyer-Biswas S, Arumugam S. Deterministic early endosomal maturations emerge from a stochastic trigger-and-convert mechanism. Nat Commun 2023; 14:4652. [PMID: 37532690 PMCID: PMC10397212 DOI: 10.1038/s41467-023-40428-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2023] [Accepted: 07/24/2023] [Indexed: 08/04/2023] Open
Abstract
Endosomal maturation is critical for robust and timely cargo transport to specific cellular compartments. The most prominent model of early endosomal maturation involves a phosphoinositide-driven gain or loss of specific proteins on individual endosomes, emphasising an autonomous and stochastic description. However, limitations in fast, volumetric imaging long hindered direct whole cell-level measurements of absolute numbers of maturation events. Here, we use lattice light-sheet imaging and bespoke automated analysis to track individual very early (APPL1-positive) and early (EEA1-positive) endosomes over the entire population, demonstrating that direct inter-endosomal contact drives maturation between these populations. Using fluorescence lifetime, we show that this endosomal interaction is underpinned by asymmetric binding of EEA1 to very early and early endosomes through its N- and C-termini, respectively. In combination with agent-based simulation which supports a 'trigger-and-convert' model, our findings indicate that APPL1- to EEA1-positive maturation is driven not by autonomous events but by heterotypic EEA1-mediated interactions, providing a mechanism for temporal and population-level control of maturation.
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Affiliation(s)
- Harrison M York
- Monash Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton/Melbourne, VIC, 3800, Australia.
| | - Kunaal Joshi
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN, 47907, USA
| | - Charles S Wright
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN, 47907, USA
| | - Laura Z Kreplin
- Monash Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton/Melbourne, VIC, 3800, Australia
| | - Samuel J Rodgers
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton/Melbourne, VIC, 3800, Australia
| | - Ullhas K Moorthi
- Monash Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton/Melbourne, VIC, 3800, Australia
| | - Hetvi Gandhi
- Monash Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton/Melbourne, VIC, 3800, Australia
| | - Abhishek Patil
- Monash Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton/Melbourne, VIC, 3800, Australia
| | - Christina A Mitchell
- Department of Biochemistry and Molecular Biology, Biomedicine Discovery Institute, Monash University, Clayton/Melbourne, VIC, 3800, Australia
| | - Srividya Iyer-Biswas
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN, 47907, USA.
- Santa Fe Institute, Santa Fe, NM, 87501, USA.
| | - Senthil Arumugam
- Monash Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences, Monash University, Clayton/Melbourne, VIC, 3800, Australia.
- ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton/Melbourne, VIC, 3800, Australia.
- European Molecular Biological Laboratory Australia (EMBL Australia), Monash University, Clayton/Melbourne, VIC, 3800, Australia.
- Single Molecule Science, University of New South Wales, Sydney, NSW, 2052, Australia.
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2
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Wang W, Bian J, Sun Y, Li Z. The new fate of internalized membrane receptors: Internalized activation. Pharmacol Ther 2021; 233:108018. [PMID: 34626676 DOI: 10.1016/j.pharmthera.2021.108018] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2021] [Revised: 10/02/2021] [Accepted: 10/04/2021] [Indexed: 12/23/2022]
Abstract
Classically, the fate of internalized membrane receptors includes receptor degradation and receptor recycling. However, recent findings have begun to challenge these views. Much research demonstrated that many internalized membrane receptors can trigger distinct signal activation rather than being desensitized inside the cell. Here, we introduce the concept of "internalized activation" which not only represents a new mode of receptor activation, but also endows the new fate for receptor internalization (from death to life). The new activation mode and fate of membrane receptor are ubiquitous and have unique theoretical significance. We systematically put forward the features, process, and regulation of "internalized activation" and its significance in signal transduction and diseases. "Internalized activation" will provide a completely new understanding for the theory of receptor activation, internalization and novel drug targets for precision medicine.
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Affiliation(s)
- Wenjing Wang
- Department of Cardiology and Institute of Vascular Medicine, Peking University Third Hospital, Beijing Key Laboratory of Cardiovascular Receptors Research, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing 100191, China
| | - Jingwei Bian
- Department of Cardiology and Institute of Vascular Medicine, Peking University Third Hospital, Beijing Key Laboratory of Cardiovascular Receptors Research, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing 100191, China
| | - Yang Sun
- Department of Cardiology and Institute of Vascular Medicine, Peking University Third Hospital, Beijing Key Laboratory of Cardiovascular Receptors Research, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing 100191, China
| | - Zijian Li
- Department of Cardiology and Institute of Vascular Medicine, Peking University Third Hospital, Beijing Key Laboratory of Cardiovascular Receptors Research, Key Laboratory of Cardiovascular Molecular Biology and Regulatory Peptides, Ministry of Health, Key Laboratory of Molecular Cardiovascular Sciences, Ministry of Education, Beijing 100191, China; Department of Pharmacy, Peking University Third Hospital, Beijing 100191, China.
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3
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Liu L, Li C, Song S, Teo ZWN, Shen L, Wang Y, Jackson D, Yu H. FTIP-Dependent STM Trafficking Regulates Shoot Meristem Development in Arabidopsis. Cell Rep 2018; 23:1879-1890. [DOI: 10.1016/j.celrep.2018.04.033] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2017] [Revised: 12/04/2017] [Accepted: 04/05/2018] [Indexed: 10/16/2022] Open
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4
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Khanna P, Chua PJ, Wong BSE, Yin C, Thike AA, Wan WK, Tan PH, Baeg GH. GRAM domain-containing protein 1B (GRAMD1B), a novel component of the JAK/STAT signaling pathway, functions in gastric carcinogenesis. Oncotarget 2017; 8:115370-115383. [PMID: 29383166 PMCID: PMC5777778 DOI: 10.18632/oncotarget.23265] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 12/03/2017] [Indexed: 12/31/2022] Open
Abstract
Dysregulated JAK/STAT signaling has been implicated in the molecular pathogenesis of gastric cancer. However, downstream effectors of STAT signaling that facilitate gastric carcinogenesis remain to be explored. We previously identified the Drosophila ortholog of human GRAMD1B in our genome-wide RNAi screen to identify novel components of the JAK/STAT signaling pathway in Drosophila. Here, we examined the involvement of GRAMD1B in JAK/STAT-associated gastric carcinogenesis. We found that GRAMD1B expression is positively regulated by JAK/STAT signaling and GRAMD1B inhibition decreases STAT3 levels, suggesting the existence of a positive feedback loop. Consistently, GRAMD1B and JAK/STAT signaling acted synergistically to promote gastric cancer cell survival by upregulating the expression of the anti-apoptotic molecule Bcl-xL. Interestingly, our immunohistochemical analysis for GRAMD1B revealed a gradual loss of cytoplasmic staining but an increase in the nuclear accumulation of GRAMD1B, as gastric tissue becomes malignant. GRAMD1B expression levels were also found to be significantly associated with clinicopathological features of the gastric cancer patients, particularly the tumor grades and lymph node status. Moreover, GRAMD1B and pSTAT3 (Tyr705) showed a positive correlation in gastric tissues, thereby confirming the existence of a close link between these two signaling molecules in vivo. This new knowledge about JAK/STAT-GRAMD1B regulation deepens our understanding of JAK/STAT signaling in gastric carcinogenesis and provides a foundation for the development of novel biomarkers in gastric cancer.
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Affiliation(s)
- Puja Khanna
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117594, Singapore
| | - Pei Jou Chua
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117594, Singapore
| | - Belinda Shu Ee Wong
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117594, Singapore
| | - Changhong Yin
- Department of Pediatrics, New York Medical College, Valhalla, NY 10595, USA
| | - Aye Aye Thike
- Division of Pathology, Singapore General Hospital, Singapore 169856, Singapore
| | - Wei Keat Wan
- Division of Pathology, Singapore General Hospital, Singapore 169856, Singapore.,Academic Clinical Program for Pathology, Duke-NUS Graduate Medical School, Singapore 169857, Singapore
| | - Puay Hoon Tan
- Division of Pathology, Singapore General Hospital, Singapore 169856, Singapore
| | - Gyeong Hun Baeg
- Department of Anatomy, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 117594, Singapore
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5
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Xu X, Wang J, Yang R, Dong Z, Zhang D. Genetic or pharmacologic inhibition of EGFR ameliorates sepsis-induced AKI. Oncotarget 2017; 8:91577-91592. [PMID: 29207668 PMCID: PMC5710948 DOI: 10.18632/oncotarget.21244] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2017] [Accepted: 08/06/2017] [Indexed: 12/19/2022] Open
Abstract
Despite recent studies have demonstrated that the EGF receptor (EGFR) activation provided a renoprotective role during ischemic and folic acid-induced AKI, the role and regulation mechanism of EGFR in septic AKI remains unclear. Here, gefitinib, a highly selective EGFR inhibitor, abrogated LPS-induced phosphorylation of EGFR, ERK1/2, and STAT3 as well as expression of COX, eNOS, and proinflammatory cytokines in HK-2 cells. In addition, c-Src is an upstream of EGFR signaling pathway and mediates LPS-induced EGFR transactivation. In vivo, either gefitinib or genetic approaches (Wave-2 mutant mice, which have reduced EGFR tyrosine kinase activity) protected against LPS or cecal ligation and puncture (CLP) induced AKI respectively. Interestingly, the beneficial effects of gefitinib or genetic approaches were accompanied by the dephosphorylation of EGFR, ERK1/2, and STAT3, the down regulation of expression of COX, eNOS, macrophage infiltration, proinflammatory cytokines production and the renal cell apoptosis. Furthermore, mRNA array results indicated that gene families involved in cell death, inflammation, proliferation and signal transduction were down regulated in Wave-2 (Wa-2) mice. Take together, these data suggest that EGFR may mediate renal injury by promoting production of inflammatory factors and cell apoptosis. Inhibition of EGFR may have therapeutic potential for AKI during endotoxemia.
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Affiliation(s)
- Xuan Xu
- Department of Emergency Medicine, Second Xiangya Hospital, Central South University, Changsha, Hunan, People's Republic of China.,Emergency Medicine and Difficult Diseases Institute, Central South University, Changsha, Hunan, People's Republic of China.,Department of Emergency Medicine, Second Affiliated Hospital of Sun Yat-Sen University, Guangzhou, Guangdong, People's Republic of China
| | - Juan Wang
- Department of Emergency Medicine, Second Xiangya Hospital, Central South University, Changsha, Hunan, People's Republic of China.,Emergency Medicine and Difficult Diseases Institute, Central South University, Changsha, Hunan, People's Republic of China
| | - Ruhao Yang
- Department of Emergency Medicine, Second Xiangya Hospital, Central South University, Changsha, Hunan, People's Republic of China.,Emergency Medicine and Difficult Diseases Institute, Central South University, Changsha, Hunan, People's Republic of China
| | - Zheng Dong
- Department of Nephrology, Second Xiangya Hospital, Central South University, Changsha, Hunan, People's Republic of China.,Department of Cellular Biology and Anatomy, Medical College of Georgia and Charlie Norwood VA Medical Center, Augusta, Georgia, USA
| | - Dongshan Zhang
- Department of Emergency Medicine, Second Xiangya Hospital, Central South University, Changsha, Hunan, People's Republic of China.,Emergency Medicine and Difficult Diseases Institute, Central South University, Changsha, Hunan, People's Republic of China.,Department of Nephrology, Second Xiangya Hospital, Central South University, Changsha, Hunan, People's Republic of China
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6
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Length effects on the dynamic process of cellular uptake and exocytosis of single-walled carbon nanotubes in murine macrophage cells. Sci Rep 2017; 7:1518. [PMID: 28490792 PMCID: PMC5431871 DOI: 10.1038/s41598-017-01746-9] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 04/07/2017] [Indexed: 12/25/2022] Open
Abstract
Cellular uptake and exocytosis of SWCNTs are fundamental processes determining their intracellular concentration and effects. Despite the great potential of acid-oxidized SWCNTs in biomedical field, understanding of the influencing factors on these processes needs to be deepened. Here, we quantitatively investigated uptake and exocytosis of SWCNTs in three lengths-630 (±171) nm (L-SWCNTs), 390 (±50) nm (M-SWCNTs), and 195 (±63) nm (S-MWCNTs) in macrophages. The results showed that the cellular accumulation of SWCNTs was a length-independent process and non-monotonic in time, with the most SWCNTs (3950 fg/cell) accumulated at 8 h and then intracellular SWCNTs dropped obviously with time. The uptake rate of SWCNTs decreased with increasing concentration, suggesting that intracellular SWCNTs accumulation is a saturable process. After refreshing culture medium, we found increasing SWCNTs in supernatant and decreasing intracellular SWCNTs over time, confirming the exocytosis occurred. Selective inhibition of endocytosis pathways showed that the internalization of SWCNTs involves several pathways, in the order of macropinocytosis> caveolae-mediated endocytosis> clathrin-dependent endocytosis. Intriguingly, clathrin-mediated endocytosis is relatively important for internalizing shorter SWCNTs. The dynamic processes of SWCNTs uptake and exocytosis and the mechanisms revealed by this study may render a better understanding on SWCNT toxicity and facilitate the design of CNT products with mitigated toxicity and desired functions.
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7
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Yuan H, Sehgal PB. MxA Is a Novel Regulator of Endosome-Associated Transcriptional Signaling by Bone Morphogenetic Proteins 4 and 9 (BMP4 and BMP9). PLoS One 2016; 11:e0166382. [PMID: 27875556 PMCID: PMC5119740 DOI: 10.1371/journal.pone.0166382] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2016] [Accepted: 10/27/2016] [Indexed: 01/02/2023] Open
Abstract
There is confusion about the role that IFN-α plays in the pathogenesis of pulmonary arterial hypertension (PAH) with different investigators reporting a causative or a protective role. There is now clear evidence in PAH pathogenesis for the involvement of BMP4 and BMP9 signaling, and its disruption by mutations in BMPR2. In the present study, we investigated MxA, an IFN-α-inducible cytoplasmic dynamin-family GTPase for effects on BMP4/9 signaling, including in the presence of PAH-disease-associated mutants of BMPR2. In human pulmonary arterial endothelial cells (HPAECs), IFN-α-induced endogenous as well as exogenously expressed MxA was associated with endosomes that aligned alongside microtubules and tubules of the endoplasmic reticulum (ER). Moreover, IFN-α and MxA stimulated basal and BMP4/9 signaling to a Smad1/5/8-responsive pBRE-Luc reporter. In HEK293T cells, immunoelectron microscopy confirmed the association of MxA with endosomes, and immunofluorescence methods showed these to be positive for early endosome markers (early endosomal antigen 1, clathrin light chain and Rab5) and RSmad1/5/8. Functionally, using different genetic and inhibitor approaches, we observed that clathrin-mediated endocytosis enhanced and caveolin-mediated endocytosis inhibited the transcriptional response to BMP4 and BMP9. MxA produced a further 3-4-fold enhancement of the BMP-induced response in a clathrin-endocytosis dependent manner. The microtubule inhibitor nocodazole and stabilizer paclitaxel respectively attenuated and enhanced the effect of MxA, implicating microtubule integrity in this process. MxA enhanced BMP-induced signaling in the presence of wild-type BMPR2, and partially rescued signaling from some PAH-disease-associated BMPR2 mutants. Taken together, the data identify MxA as a novel stimulator of BMP4 and BMP9 transcriptional signaling, and suggest it to be a candidate IFN-α-inducible mechanism that might have a protective role against development of PAH and other vascular diseases.
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Affiliation(s)
- Huijuan Yuan
- Department of. Cell Biology & Anatomy, New York Medical College, Valhalla, New York, United States of America
| | - Pravin B. Sehgal
- Department of. Cell Biology & Anatomy, and Department of Medicine, New York Medical College, Valhalla, New York, United States of America
- * E-mail:
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8
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Widera D, Klenke C, Nair D, Heidbreder M, Malkusch S, Sibarita JB, Choquet D, Kaltschmidt B, Heilemann M, Kaltschmidt C. Single-particle tracking uncovers dynamics of glutamate-induced retrograde transport of NF-κB p65 in living neurons. NEUROPHOTONICS 2016; 3:041804. [PMID: 27226975 PMCID: PMC4870386 DOI: 10.1117/1.nph.3.4.041804] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 04/18/2016] [Indexed: 06/05/2023]
Abstract
Retrograde transport of NF-κB from the synapse to the nucleus in neurons is mediated by the dynein/dynactin motor complex and can be triggered by synaptic activation. The caliber of axons is highly variable ranging down to 100 nm, aggravating the investigation of transport processes in neurites of living neurons using conventional light microscopy. We quantified for the first time the transport of the NF-κB subunit p65 using high-density single-particle tracking in combination with photoactivatable fluorescent proteins in living mouse hippocampal neurons. We detected an increase of the mean diffusion coefficient ([Formula: see text]) in neurites from [Formula: see text] to [Formula: see text] after stimulation with glutamate. We further observed that the relative amount of retrogradely transported p65 molecules is increased after stimulation. Glutamate treatment resulted in an increase of the mean retrograde velocity from [Formula: see text] to [Formula: see text], whereas a velocity increase from [Formula: see text] to [Formula: see text] was observed for anterogradely transported p65. This study demonstrates for the first time that glutamate stimulation leads to an increased mobility of single NF-κB p65 molecules in neurites of living hippocampal neurons.
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Affiliation(s)
- Darius Widera
- University of Bielefeld, Cell Biology, Universitätsstr. 25, 33501 Bielefeld, Germany
- University of Reading, School of Pharmacy, Stem Cell Biology and Regenerative Medicine, Whiteknights, Reading RG6 6UB, United Kingdom
| | - Christin Klenke
- University of Bielefeld, Cell Biology, Universitätsstr. 25, 33501 Bielefeld, Germany
| | - Deepak Nair
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, 146 rue Léo-Saignat, Bordeaux 33077, France
- CNRS UMR 5297, 146 rue Léo-Saignat, Bordeaux 33077, France
| | - Meike Heidbreder
- Julius-Maximilians-Universität, Department of Biotechnology and Biophysics, Am Hubland, Würzburg 97074, Germany
| | - Sebastian Malkusch
- Johann Wolfgang Goethe-University, Institute for Physical and Theoretical Chemistry, Max-von-Laue-Street 7, Frankfurt 60438, Germany
| | - Jean-Baptiste Sibarita
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, 146 rue Léo-Saignat, Bordeaux 33077, France
- CNRS UMR 5297, 146 rue Léo-Saignat, Bordeaux 33077, France
- Bordeaux Imaging Center, UMS 3420 CNRS, US4 INSERM, France
| | - Daniel Choquet
- University of Bordeaux, Interdisciplinary Institute for Neuroscience, 146 rue Léo-Saignat, Bordeaux 33077, France
- CNRS UMR 5297, 146 rue Léo-Saignat, Bordeaux 33077, France
| | - Barbara Kaltschmidt
- University of Bielefeld, Cell Biology, Universitätsstr. 25, 33501 Bielefeld, Germany
- University of Bielefeld, Molecular Neurobiology, Universitätsstr. 25, Bielefeld 33501, Germany
| | - Mike Heilemann
- Johann Wolfgang Goethe-University, Institute for Physical and Theoretical Chemistry, Max-von-Laue-Street 7, Frankfurt 60438, Germany
| | - Christian Kaltschmidt
- University of Bielefeld, Cell Biology, Universitätsstr. 25, 33501 Bielefeld, Germany
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9
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Konopacki FA, Wong HHW, Dwivedy A, Bellon A, Blower MD, Holt CE. ESCRT-II controls retinal axon growth by regulating DCC receptor levels and local protein synthesis. Open Biol 2016; 6:150218. [PMID: 27248654 PMCID: PMC4852451 DOI: 10.1098/rsob.150218] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 03/13/2016] [Indexed: 01/08/2023] Open
Abstract
Endocytosis and local protein synthesis (LPS) act coordinately to mediate the chemotropic responses of axons, but the link between these two processes is poorly understood. The endosomal sorting complex required for transport (ESCRT) is a key regulator of cargo sorting in the endocytic pathway, and here we have investigated the role of ESCRT-II, a critical ESCRT component, in Xenopus retinal ganglion cell (RGC) axons. We show that ESCRT-II is present in RGC axonal growth cones (GCs) where it co-localizes with endocytic vesicle GTPases and, unexpectedly, with the Netrin-1 receptor, deleted in colorectal cancer (DCC). ESCRT-II knockdown (KD) decreases endocytosis and, strikingly, reduces DCC in GCs and leads to axon growth and guidance defects. ESCRT-II-depleted axons fail to turn in response to a Netrin-1 gradient in vitro and many axons fail to exit the eye in vivo. These defects, similar to Netrin-1/DCC loss-of-function phenotypes, can be rescued in whole (in vitro) or in part (in vivo) by expressing DCC. In addition, ESCRT-II KD impairs LPS in GCs and live imaging reveals that ESCRT-II transports mRNAs in axons. Collectively, our results show that the ESCRT-II-mediated endocytic pathway regulates both DCC and LPS in the axonal compartment and suggest that ESCRT-II aids gradient sensing in GCs by coupling endocytosis to LPS.
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Affiliation(s)
- Filip A Konopacki
- Department of Physiology Development Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Hovy Ho-Wai Wong
- Department of Physiology Development Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Asha Dwivedy
- Department of Physiology Development Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Anaïs Bellon
- Department of Physiology Development Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Michael D Blower
- Department of Molecular Biology, Harvard Medical School, Simches Research Center, Boston, MA 02114, USA
| | - Christine E Holt
- Department of Physiology Development Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
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10
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Ehrlich M. Endocytosis and trafficking of BMP receptors: Regulatory mechanisms for fine-tuning the signaling response in different cellular contexts. Cytokine Growth Factor Rev 2015; 27:35-42. [PMID: 26776724 DOI: 10.1016/j.cytogfr.2015.12.008] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Signaling by bone morphogenetic protein (BMP) receptors is regulated at multiple levels in order to ensure proper interpretation of BMP stimuli in different cellular settings. As with other signaling receptors, regulation of the amount of exposed and signaling-competent BMP receptors at the plasma-membrane is predicted to be a key mechanism in governing their signaling output. Currently, the endocytosis of BMP receptors is thought to resemble that of the structurally related transforming growth factor-β (TGF-β) receptors, as BMP receptors are constitutively internalized (independently of ligand binding), with moderate kinetics, and mostly via clathrin-mediated endocytosis. Also similar to TGF-β receptors, BMP receptors are able to signal from the plasma membrane, while internalization to endosomes may have a signal modulating effect. When at the plasma membrane, BMP receptors localize to different membrane domains including cholesterol rich domains and caveolae, suggesting a complex interplay between membrane distribution and internalization. An additional layer of complexity stems from the putative regulatory influence on the signaling and trafficking of BMP receptors exerted by ligand traps and/or co-receptors. Furthermore, the trafficking and signaling of BMP receptors are subject to alterations in cellular context. For example, genetic diseases involving changes in the expression of auxiliary factors of endocytic pathways hamper retrograde BMP signals in neurons, and perturb the regulation of synapse formation. This review summarizes current understanding of the trafficking of BMP receptors and discusses the role of trafficking in regulation of BMP signals.
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Affiliation(s)
- Marcelo Ehrlich
- Department of Cell Research and Immunology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel.
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11
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Blount MA, Cipriani P, Redd SK, Ordas RJ, Black LN, Gumina DL, Hoban CA, Klein JD, Sands JM. Activation of protein kinase Cα increases phosphorylation of the UT-A1 urea transporter at serine 494 in the inner medullary collecting duct. Am J Physiol Cell Physiol 2015; 309:C608-15. [PMID: 26333598 PMCID: PMC4628937 DOI: 10.1152/ajpcell.00171.2014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2014] [Accepted: 08/18/2015] [Indexed: 01/20/2023]
Abstract
Hypertonicity increases urea transport, as well as the phosphorylation and membrane accumulation of UT-A1, the transporter responsible for urea permeability in the inner medullary collect duct (IMCD). Hypertonicity stimulates urea transport through PKC-mediated phosphorylation. To determine whether PKC phosphorylates UT-A1, eight potential PKC phosphorylation sites were individually replaced with alanine and subsequently transfected into LLC-PK1 cells. Of the single mutants, only ablation of the S494 site dampened induction of total UT-A1 phosphorylation by the PKC activator phorbol dibutyrate (PDBu). This result was confirmed using a newly generated antibody that specifically detected phosphorylation of UT-A1 at S494. Hypertonicity increased UT-A1 phosphorylation at S494. In contrast, activators of cAMP pathways (PKA and Epac) did not increase UT-A1 phosphorylation at S494. Activation of both PKC and PKA pathways increased plasma membrane accumulation of UT-A1, although activation of PKC alone did not do so. However, ablating the PKC site S494 decreased UT-A1 abundance in the plasma membrane. This suggests that the cAMP pathway promotes UT-A1 trafficking to the apical membrane where the PKC pathway can phosphorylate the transporter, resulting in increased UT-A1 retention at the apical membrane. In summary, activation of PKC increases the phosphorylation of UT-A1 at a specific residue, S494. Although there is no cross talk with the cAMP-signaling pathway, phosphorylation of S494 through PKC may enhance vasopressin-stimulated urea permeability by retaining UT-A1 in the plasma membrane.
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Affiliation(s)
- Mitsi A Blount
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; and Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Penelope Cipriani
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; and
| | - Sara K Redd
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; and
| | - Ronald J Ordas
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; and
| | - Lauren N Black
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; and
| | - Diane L Gumina
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; and
| | - Carol A Hoban
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; and
| | - Janet D Klein
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; and Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
| | - Jeff M Sands
- Renal Division, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia; and Department of Physiology, Emory University School of Medicine, Atlanta, Georgia
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12
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Wang X, Schröder HC, Müller WEG. Polyphosphate as a metabolic fuel in Metazoa: A foundational breakthrough invention for biomedical applications. Biotechnol J 2015; 11:11-30. [PMID: 26356505 DOI: 10.1002/biot.201500168] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2015] [Revised: 07/24/2015] [Accepted: 08/19/2015] [Indexed: 12/17/2022]
Abstract
In animals, energy-rich molecules like ATP are generated in the intracellular compartment from metabolites, e.g. glucose, taken up by the cells. Recent results revealed that inorganic polyphosphates (polyP) can provide an extracellular system for energy transport and delivery. These polymers of multiple phosphate units, linked by high-energy phosphoanhydride bonds, use blood platelets as transport vehicles to reach their target cells. In this review it is outlined how polyP affects cell metabolism. It is discussed that polyP influences cell activity in a dual way: (i) as a metabolic fuel transferring metabolic energy through the extracellular space; and (ii) as a signaling molecule that amplifies energy/ATP production in mitochondria. Several metabolic pathways are triggered by polyP, among them biomineralization/hydroxyapatite formation onto bone cells. The accumulation of polyP in the platelets allows long-distance transport of the polymer in the extracellular space. The discovery of polyP as metabolic fuel and signaling molecule initiated the development of novel techniques for encapsulation of polyP into nanoparticles. They facilitate cellular uptake of the polymer by receptor-mediated endocytosis and allow the development of novel strategies for therapy of metabolic diseases associated with deviations in energy metabolism or mitochondrial dysfunctions.
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Affiliation(s)
- Xiaohong Wang
- ERC Advanced Investigator Grant Research Group at the Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Mainz, Rheinland-Pfalz, Germany.
| | - Heinz C Schröder
- ERC Advanced Investigator Grant Research Group at the Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Mainz, Rheinland-Pfalz, Germany
| | - Werner E G Müller
- ERC Advanced Investigator Grant Research Group at the Institute for Physiological Chemistry, University Medical Center of the Johannes Gutenberg University, Mainz, Rheinland-Pfalz, Germany.
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13
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Ch'ng TH, DeSalvo M, Lin P, Vashisht A, Wohlschlegel JA, Martin KC. Cell biological mechanisms of activity-dependent synapse to nucleus translocation of CRTC1 in neurons. Front Mol Neurosci 2015; 8:48. [PMID: 26388727 PMCID: PMC4560099 DOI: 10.3389/fnmol.2015.00048] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2015] [Accepted: 08/18/2015] [Indexed: 12/27/2022] Open
Abstract
Previous studies have revealed a critical role for CREB-regulated transcriptional coactivator (CRTC1) in regulating neuronal gene expression during learning and memory. CRTC1 localizes to synapses but undergoes activity-dependent nuclear translocation to regulate the transcription of CREB target genes. Here we investigate the long-distance retrograde transport of CRTC1 in hippocampal neurons. We show that local elevations in calcium, triggered by activation of glutamate receptors and L-type voltage-gated calcium channels, initiate active, dynein-mediated retrograde transport of CRTC1 along microtubules. We identify a nuclear localization signal within CRTC1, and characterize three conserved serine residues whose dephosphorylation is required for nuclear import. Domain analysis reveals that the amino-terminal third of CRTC1 contains all of the signals required for regulated nucleocytoplasmic trafficking. We fuse this region to Dendra2 to generate a reporter construct and perform live-cell imaging coupled with local uncaging of glutamate and photoconversion to characterize the dynamics of stimulus-induced retrograde transport and nuclear accumulation.
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Affiliation(s)
- Toh Hean Ch'ng
- Lee Kong Chian School of Medicine, Nanyang Technological University Singapore, Singapore ; School of Biological Sciences, Nanyang Technological University Singapore, Singapore
| | - Martina DeSalvo
- Department of Biological Chemistry, University of California, Los Angeles Los Angeles, CA, USA
| | - Peter Lin
- Department of Neurology and Neuroscience, Stanford University Palo Alto, CA, USA
| | - Ajay Vashisht
- Department of Biological Chemistry, University of California, Los Angeles Los Angeles, CA, USA
| | - James A Wohlschlegel
- Department of Biological Chemistry, University of California, Los Angeles Los Angeles, CA, USA
| | - Kelsey C Martin
- Department of Biological Chemistry, University of California, Los Angeles Los Angeles, CA, USA ; Department of Psychiatry and Biobehavioral Sciences, University of California, Los Angeles Los Angeles, CA, USA
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14
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Chua CEL, Tang BL. Role of Rab GTPases and their interacting proteins in mediating metabolic signalling and regulation. Cell Mol Life Sci 2015; 72:2289-304. [PMID: 25690707 PMCID: PMC11113524 DOI: 10.1007/s00018-015-1862-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Revised: 02/09/2015] [Accepted: 02/11/2015] [Indexed: 10/24/2022]
Abstract
The vesicular transport pathways, which shuttle materials to and from the cell surface and within the cell, and the metabolic (growth factor and nutrient) signalling pathways, which integrate a variety of extracellular and intracellular signals to mediate growth, proliferation or survival, are both important for cellular physiology. There is evidence to suggest that the transport and metabolic signalling pathways intersect-vesicular transport can affect the regulation of metabolic signals and vice versa. The Rab family GTPases regulate the specificity of vesicular transport steps in the cell. Together with their interacting proteins, Rabs would likely constitute the points of intersection between vesicular transport and metabolic signalling pathways. Examples of these points would include growth factor signalling, glucose and lipid metabolism, as well as autophagy. Many of these processes involve mechanistic/mammalian target of rapamycin (mTOR) complex 1 (mTORC1) in downstream cascades, or are regulated by TORC signalling. A general functionality of the vesicular transport processes controlled by the Rabs is also important for spatial and temporal regulation of the transmission of metabolic signals between the cell surface and the nucleus. In other cases, specific Rabs and their interacting proteins are known to function in recruiting metabolism-related proteins to target membranes, or may compete with other factors in the TORC signalling pathway as a means of metabolic regulation. We review and discuss herein examples of how Rabs and their interacting proteins can mediate metabolic signalling and regulation in cells.
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Affiliation(s)
- Christelle En Lin Chua
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University Health System, 8 Medical Drive, Singapore, 117597, Singapore,
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15
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Wu S, Gallagher KL. The movement of the non-cell-autonomous transcription factor, SHORT-ROOT relies on the endomembrane system. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 80:396-409. [PMID: 25124761 DOI: 10.1111/tpj.12640] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Revised: 07/29/2014] [Accepted: 08/04/2014] [Indexed: 05/08/2023]
Abstract
Plant cells are able to convey positional and developmental information between cells through the direct transfer of transcription factors. One well studied example of this is the SHORT-ROOT (SHR) protein, which moves from the stele into the neighboring ground tissue layer to specify endodermis. While it has been shown that SHR trafficking relies on plasmodesmata (PD), and interaction with the SHR INTERACTING EMBRYONIC LETHAL (SIEL) protein, little information is known about how SHR trafficking is controlled or how SIEL promotes the movement of SHR. Here we show that SHR can move from multiple different cell types in the root. Analysis of subcellular localization indicates that in the cytoplasm of root or leaf cells, SHR localizes to endosomes in a SIEL-dependent manner. Interference of early and late endosomes disrupts intercellular movement of SHR. Our findings reveal an essential role for the plant endomembrane, independent of secretion, in the intercellular trafficking of SHR.
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Affiliation(s)
- Shuang Wu
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA
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16
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Kaushik R, Grochowska KM, Butnaru I, Kreutz MR. Protein trafficking from synapse to nucleus in control of activity-dependent gene expression. Neuroscience 2014; 280:340-50. [PMID: 25230285 DOI: 10.1016/j.neuroscience.2014.09.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Revised: 08/18/2014] [Accepted: 09/04/2014] [Indexed: 10/24/2022]
Abstract
Long-lasting changes in neuronal excitability require activity-dependent gene expression and therefore the transduction of synaptic signals to the nucleus. Synaptic activity is rapidly relayed to the nucleus by membrane depolarization and the propagation of Ca(2+)-waves. However, it is unlikely that Ca(2+)-transients alone can explain the specific genomic response to the plethora of extracellular stimuli that control gene expression. In recent years a steadily growing number of studies report the transport of proteins from synapse to nucleus. Potential mechanisms for active retrograde transport and nuclear targets for these proteins have been identified and recent reports assigned first functions to this type of long-distance signaling. In this review we will discuss how the dissociation of synapto-nuclear protein messenger from synaptic and extrasynaptic sites, their transport, nuclear import and the subsequent genomic response relate to the prevailing concept behind this signaling mechanism, the encoding of signals at their site of origin and their decoding in the nucleus.
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Affiliation(s)
- R Kaushik
- Neuroplasticity Research Group, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - K M Grochowska
- Neuroplasticity Research Group, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - I Butnaru
- Neuroplasticity Research Group, Leibniz Institute for Neurobiology, Magdeburg, Germany
| | - M R Kreutz
- Neuroplasticity Research Group, Leibniz Institute for Neurobiology, Magdeburg, Germany.
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17
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Matusica D, Coulson EJ. Local versus long-range neurotrophin receptor signalling: endosomes are not just carriers for axonal transport. Semin Cell Dev Biol 2014; 31:57-63. [PMID: 24709025 DOI: 10.1016/j.semcdb.2014.03.032] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2014] [Revised: 03/24/2014] [Accepted: 03/31/2014] [Indexed: 01/25/2023]
Abstract
Neurotrophins play a critical role in neuronal development and survival, as well as maintenance of the adult nervous system. Neurotrophins can mediate their effects by signalling locally at the nerve terminal, or signalling retrogradely from the axonal terminal to the cell soma to regulate gene expression. Given that the axon terminals of many nerve cells can be up to a metre away from their soma, neurons have evolved specialized long-range signalling platforms that depend on a highly regulated network of intracellular membrane compartments termed "signalling endosomes". Endosomal trafficking of activated receptors controls not only the axonal retrograde signals but also local receptor recycling and degradation. Endosomal trafficking involving the sorting and compartmentalizing of different signals, which are subsequently distributed to the appropriate cellular destination, can at least partially explain how neurotrophins generate a diverse array of signalling outcomes. Although signalling endosomes provide a useful model for understanding how different cell surface receptor-mediated signals are generated and transported, the precise role, identity and functional definition of a signalling endosome remains unclear. In this review we will discuss the regulation of local versus long-range neurotrophin signalling, with a specific focus on recent developments in the role of endosomes in regulating the fate of Trk receptors.
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Affiliation(s)
- Dusan Matusica
- The Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane 4072 Qld, Australia
| | - Elizabeth J Coulson
- The Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane 4072 Qld, Australia.
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18
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Schmieg N, Menendez G, Schiavo G, Terenzio M. Signalling endosomes in axonal transport: Travel updates on the molecular highway. Semin Cell Dev Biol 2014; 27:32-43. [DOI: 10.1016/j.semcdb.2013.10.004] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2013] [Revised: 10/17/2013] [Accepted: 10/19/2013] [Indexed: 01/11/2023]
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19
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Targeted Materials. Drug Deliv 2014. [DOI: 10.1007/978-1-4939-1998-7_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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20
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Miaczynska M. Effects of membrane trafficking on signaling by receptor tyrosine kinases. Cold Spring Harb Perspect Biol 2013; 5:a009035. [PMID: 24186066 DOI: 10.1101/cshperspect.a009035] [Citation(s) in RCA: 93] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The intracellular trafficking machinery contributes to the spatial and temporal control of signaling by receptor tyrosine kinases (RTKs). The primary role in this process is played by endocytic trafficking, which regulates the localization of RTKs and their downstream effectors, as well as the duration and the extent of their activity. The key regulatory points along the endocytic pathway are internalization of RTKs from the plasma membrane, their sorting to degradation or recycling, and their residence in various endosomal compartments. Here I will review factors and mechanisms that modulate RTK signaling by (1) affecting receptor internalization, (2) regulating the balance between degradation and recycling of RTK, and (3) compartmentalization of signals in endosomes and other organelles. Cumulatively, these mechanisms illustrate a multilayered control of RTK signaling exerted by the trafficking machinery.
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Affiliation(s)
- Marta Miaczynska
- International Institute of Molecular and Cell Biology, Laboratory of Cell Biology, 02-109 Warsaw, Poland
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21
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Mohanty A, McBride HM. Emerging roles of mitochondria in the evolution, biogenesis, and function of peroxisomes. Front Physiol 2013; 4:268. [PMID: 24133452 PMCID: PMC3783979 DOI: 10.3389/fphys.2013.00268] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Accepted: 09/10/2013] [Indexed: 12/19/2022] Open
Abstract
In the last century peroxisomes were thought to have an endosymbiotic origin. Along with mitochondria and chloroplasts, peroxisomes primarily regulate their numbers through the growth and division of pre-existing organelles, and they house specific machinery for protein import. These features were considered unique to endosymbiotic organelles, prompting the idea that peroxisomes were key cellular elements that helped facilitate the evolution of multicellular organisms. The functional similarities to mitochondria within mammalian systems expanded these ideas, as both organelles scavenge peroxide and reactive oxygen species, both organelles oxidize fatty acids, and at least in higher eukaryotes, the biogenesis of both organelles is controlled by common nuclear transcription factors of the PPAR family. Over the last decade it has been demonstrated that the fission machinery of both organelles is also shared, and that both organelles act as critical signaling platforms for innate immunity and other pathways. Taken together it is clear that the mitochondria and peroxisomes are functionally coupled, regulating cellular metabolism and signaling through a number of common mechanisms. However, recent work has focused primarily on the role of the ER in the biogenesis of peroxisomes, potentially overshadowing the critical importance of the mitochondria as a functional partner. In this review, we explore the mechanisms of functional coupling of the peroxisomes to the mitochondria/ER networks, providing some new perspectives on the potential contribution of the mitochondria to peroxisomal biogenesis.
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Affiliation(s)
- Abhishek Mohanty
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University Montreal, QC, Canada
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22
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Harada H, Warabi E, Matsuki T, Yanagawa T, Okada K, Uwayama J, Ikeda A, Nakaso K, Kirii K, Noguchi N, Bukawa H, Siow RCM, Mann GE, Shoda J, Ishii T, Sakurai T. Deficiency of p62/Sequestosome 1 causes hyperphagia due to leptin resistance in the brain. J Neurosci 2013; 33:14767-77. [PMID: 24027277 PMCID: PMC6705174 DOI: 10.1523/jneurosci.2954-12.2013] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Revised: 08/05/2013] [Accepted: 08/07/2013] [Indexed: 01/08/2023] Open
Abstract
The cytoplasmic regulatory protein p62 (Sequestosome 1/A170) is known to modulate various receptor-mediated intracellular signaling pathways. p62 deficiency was shown to result in mature-onset obesity in mice, but the mechanisms underlying this abnormality remained unclear. Here we report that hyperphagia due to central leptin resistance is the cause of obesity in p62(-/-) mice. We found that these mice show hyperphagia. Restriction of food to the amount eaten by wild-type mice prevented excess body weight gain and fat accumulation, suggesting that overfeeding is the primary cause of obesity in p62(-/-) mice. Brain-specific p62 deficiency caused mature-onset obesity to the same extent as in p62(-/-) mice, further supporting a neuronal mechanism as the major cause of obesity in these mice. Immunohistochemical analysis revealed that p62 is highly expressed in hypothalamic neurons, including POMC neurons in the arcuate nucleus. Central leptin resistance was observed even in young preobese p62(-/-) mice. We found a defect in intracellular distribution of the transcription factor Stat3, which is essential for the action of leptin, in p62(-/-) mice. These results indicate that brain p62 plays an important role in bodyweight control by modulating the central leptin-signaling pathway and that lack of p62 in the brain causes leptin resistance, leading to hyperphagia. Thus, p62 could be a clinical target for treating obesity and metabolic syndrome.
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Affiliation(s)
- Harumi Harada
- Majors of Medical Sciences, University of Tsukuba, Ibaraki 305-8575, Japan
| | - Eiji Warabi
- Majors of Medical Sciences, University of Tsukuba, Ibaraki 305-8575, Japan
| | - Taizo Matsuki
- Department of Molecular Neuroscience and Integrative Physiology, Faculty of Medicine, Kanazawa University, Kanazawa, Ishikawa 920-8640, Japan
- Center for Behavioral Molecular Genetics, University of Tsukuba, Ibaraki 305-8575, Japan
| | - Toru Yanagawa
- Majors of Medical Sciences, University of Tsukuba, Ibaraki 305-8575, Japan
| | - Kosuke Okada
- Majors of Medical Sciences, University of Tsukuba, Ibaraki 305-8575, Japan
| | - Junya Uwayama
- Majors of Medical Sciences, University of Tsukuba, Ibaraki 305-8575, Japan
| | - Akira Ikeda
- Majors of Medical Sciences, University of Tsukuba, Ibaraki 305-8575, Japan
| | - Kazuhiro Nakaso
- Department of Neurology, Institute of Neurological Sciences, Faculty of Medicine, Tottori University, Yonago, Tottori 683-8504, Japan
| | - Kyoko Kirii
- Majors of Medical Sciences, University of Tsukuba, Ibaraki 305-8575, Japan
| | - Noriko Noguchi
- Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, Kyoto 610-0321, Japan, and
| | - Hiroki Bukawa
- Majors of Medical Sciences, University of Tsukuba, Ibaraki 305-8575, Japan
| | - Richard C. M. Siow
- Cardiovascular Division, British Heart Foundation Centre of Research Excellence, School of Medicine, King's College London, London SE1 9NH, United Kingdom
| | - Giovanni E. Mann
- Cardiovascular Division, British Heart Foundation Centre of Research Excellence, School of Medicine, King's College London, London SE1 9NH, United Kingdom
| | - Junichi Shoda
- Majors of Medical Sciences, University of Tsukuba, Ibaraki 305-8575, Japan
| | - Tetsuro Ishii
- Majors of Medical Sciences, University of Tsukuba, Ibaraki 305-8575, Japan
| | - Takeshi Sakurai
- Department of Molecular Neuroscience and Integrative Physiology, Faculty of Medicine, Kanazawa University, Kanazawa, Ishikawa 920-8640, Japan
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23
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Pálfy M, Reményi A, Korcsmáros T. Endosomal crosstalk: meeting points for signaling pathways. Trends Cell Biol 2012; 22:447-56. [PMID: 22796207 PMCID: PMC3430897 DOI: 10.1016/j.tcb.2012.06.004] [Citation(s) in RCA: 89] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2012] [Revised: 06/18/2012] [Accepted: 06/19/2012] [Indexed: 12/30/2022]
Abstract
Endocytosis participates in downregulating incoming signals, but 'signaling endosomes' may also serve as physical platforms for crosstalk between signaling pathways. Here, we briefly review the role of endosomes in signaling crosstalk and suggest that endosome-associated scaffold proteins mediate this crosstalk. In addition, using a proteome-wide in silico approach - in which we analyze endosome-binding properties and the capacity of candidates to recruit signaling proteins from more than one distinct pathway - we extend the list of putative crosstalk-mediating endosomal scaffolds. Because endosomal crosstalk may be an important systems-level regulator of pathway communication, scaffold proteins that mediate this crosstalk could be potential targets for pharmacological intervention and synthetic engineering.
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Affiliation(s)
- Máté Pálfy
- Department of Genetics, Eötvös Loránd University, Pázmány P. s. 1/C, Budapest, H-1117, Hungary
| | - Attila Reményi
- Department of Biochemistry, Eötvös Loránd University, Pázmány P. s. 1/C, Budapest, H-1117, Hungary
| | - Tamás Korcsmáros
- Department of Genetics, Eötvös Loránd University, Pázmány P. s. 1/C, Budapest, H-1117, Hungary
- Department of Medical Chemistry, Semmelweis University, Tűzoltó u. 37-47, Budapest, H-1094, Hungary
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24
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Grecco HE, Schmick M, Bastiaens PIH. Signaling from the living plasma membrane. Cell 2011; 144:897-909. [PMID: 21414482 DOI: 10.1016/j.cell.2011.01.029] [Citation(s) in RCA: 180] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 12/10/2010] [Accepted: 01/17/2011] [Indexed: 02/06/2023]
Abstract
Our understanding of the plasma membrane, once viewed simply as a static barrier, has been revolutionized to encompass a complex, dynamic organelle that integrates the cell with its extracellular environment. Here, we discuss how bidirectional signaling across the plasma membrane is achieved by striking a delicate balance between restriction and propagation of information over different scales of time and space and how underlying dynamic mechanisms give rise to rich, context-dependent signaling responses. In this Review, we show how computer simulations can generate counterintuitive predictions about the spatial organization of these complex processes.
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Affiliation(s)
- Hernán E Grecco
- Max Planck Institute for Molecular Physiology, Department of Systemic Cell Biology, Otto-Hahn-Str. 11, D-44227 Dortmund, Germany
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25
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German CL, Sauer BM, Howe CL. The STAT3 beacon: IL-6 recurrently activates STAT 3 from endosomal structures. Exp Cell Res 2011; 317:1955-69. [PMID: 21619877 DOI: 10.1016/j.yexcr.2011.05.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 05/10/2011] [Accepted: 05/10/2011] [Indexed: 01/12/2023]
Abstract
Endocytic trafficking plays an important role in signal transduction. Signal transducer and activator of transcription 3 (STAT3) and mitogen-activate protein kinase (MAPK) have both been localized to endosomal structures and are dependent upon endocytosis for downstream function. While the dependence of MAPK signaling upon endosomes has been well characterized, the involvement of endosomes in regulating STAT3 signaling has not been defined. Consequently, this study evaluated the role of endosomes in the initiation, modulation, amplification and persistence of interleukin-6(IL-6)-induced STAT3 signal transduction and transcription, and utilized IL-6-induced MAPK signaling as a comparator. Using pharmacologic treatment and temperature control of endocytic trafficking, pulse-chase treatments and in vitro kinase assays, STAT3 was found to interact with endosomes in a markedly different fashion than MAPK. STAT3 was activated by direct interaction with internal structures upstream of the late endosome following IL-6 exposure and persistent STAT3 signaling depended upon recurrent activation from endocytic structures. Further, STAT3 subcellular localization was not dependent upon endocytic trafficking. Instead, STAT3 transiently interacted with endosomes and relocated to the nucleus by an endosome-independent mechanism. Finally, endocytic trafficking played a central role in regulating STAT3 serine 727 phosphorylation through crosstalk with the MAPK signaling system. Together, these data reveal endosomes as central to the genesis, course and outcome of STAT3 signal transduction and transcription.
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Affiliation(s)
- Christopher L German
- Program in Molecular Neuroscience, Mayo Clinic College of Medicine, 200 First ST SW, Rochester, MN 55905, USA.
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26
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Ch'ng TH, Martin KC. Synapse-to-nucleus signaling. Curr Opin Neurobiol 2011; 21:345-52. [PMID: 21349698 DOI: 10.1016/j.conb.2011.01.011] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2011] [Revised: 01/31/2011] [Accepted: 01/31/2011] [Indexed: 12/21/2022]
Abstract
Signals generated in distal subcellular compartments of neurons must often travel long distances to the nucleus to trigger changes in gene expression. This retrograde signaling is critical to the development, function, and survival of neural circuits, and neurons have evolved multiple mechanisms to transmit signals over long distances. In this review, we briefly summarize the range of mechanisms whereby distally generated signals are transported to neuronal nuclei. We then focus on the transport of soluble signals from the synapse to the nucleus during neuronal plasticity.
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Affiliation(s)
- Toh Hean Ch'ng
- Department of Biological Chemistry, David Geffen School of Medicine, University of California, Los Angeles, CA 90095-1737, United States
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27
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Multi-scale spatio-temporal modeling: lifelines of microorganisms in bioreactors and tracking molecules in cells. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2010; 121:23-43. [PMID: 20140659 DOI: 10.1007/10_2009_53] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Agent-based models are rigorous tools for simulating the interactions of individual entities, such as organisms or molecules within cells and assessing their effects on the dynamic behavior of the system as a whole. In context with bioprocess and biosystems engineering there are several interesting and important applications. This contribution aims at introducing this strategy with the aid of two examples characterized by striking distinctions in the scale of the individual entities and the mode of their interactions. In the first example a structured-segregated model is applied to travel along the lifelines of single cells in the environment of a three-dimensional turbulent field of a stirred bioreactor. The modeling approach is based on an Euler-Lagrange formulation of the system. The strategy permits one to account for the heterogeneity present in real reactors in both the fluid and cellular phases, respectively. The individual response of the cells to local variations in the extracellular concentrations is pictured by a dynamically structured model of the key reactions of the central metabolism. The approach permits analysis of the lifelines of individual cells in space and time.The second application of the individual modeling approach deals with dynamic modeling of signal transduction pathways in individual cells. Usually signal transduction networks are portrayed as being wired together in a spatially defined manner. Living circuitry, however, is placed in highly malleable internal architecture. Creating a homogenous bag of molecules, a well-mixed system, the dynamic behavior of which is modeled with a set of ordinary differential equations is normally not valid. The dynamics of the MAP kinase and a steroid hormone pathway serve as examples to illustrate how single molecule tracking can be linked with the stochasticity of biochemical reactions, where diffusion and reaction occur in a probabilistic manner. The problem of hindered diffusion caused by macromolecular crowding is also taken into account.
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28
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Kam N, Pilpel Y, Fainzilber M. Can molecular motors drive distance measurements in injured neurons? PLoS Comput Biol 2009; 5:e1000477. [PMID: 19696880 PMCID: PMC2718615 DOI: 10.1371/journal.pcbi.1000477] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2009] [Accepted: 07/20/2009] [Indexed: 11/18/2022] Open
Abstract
Injury to nerve axons induces diverse responses in neuronal cell bodies, some of which are influenced by the distance from the site of injury. This suggests that neurons have the capacity to estimate the distance of the injury site from their cell body. Recent work has shown that the molecular motor dynein transports importin-mediated retrograde signaling complexes from axonal lesion sites to cell bodies, raising the question whether dynein-based mechanisms enable axonal distance estimations in injured neurons? We used computer simulations to examine mechanisms that may provide nerve cells with dynein-dependent distance assessment capabilities. A multiple-signals model was postulated based on the time delay between the arrival of two or more signals produced at the site of injury–a rapid signal carried by action potentials or similar mechanisms and slower signals carried by dynein. The time delay between the arrivals of these two types of signals should reflect the distance traversed, and simulations of this model show that it can indeed provide a basis for distance measurements in the context of nerve injuries. The analyses indicate that the suggested mechanism can allow nerve cells to discriminate between distances differing by 10% or more of their total axon length, and suggest that dynein-based retrograde signaling in neurons can be utilized for this purpose over different scales of nerves and organisms. Moreover, such a mechanism might also function in synapse to nucleus signaling in uninjured neurons. This could potentially allow a neuron to dynamically sense the relative lengths of its processes on an ongoing basis, enabling appropriate metabolic output from cell body to processes. Neurons have extremely long axonal processes that can reach lengths of up to 1 meter in human peripheral nerves. The neuronal cell body response to nerve injury is dependent on signals carried by molecular motors from the lesion site in the axon. The distance between the injury site and the cell body influences the type of response, suggesting that neurons must be able to estimate the distance of an axonal injury site, although how they do this is unknown. We have used a computational approach to model intracellular distance measurement after nerve injury. The models show the feasibility of a mechanism based on a rapid, near instantaneous, signal carried by action potentials in the nerve, followed by multiple slower signals carried on molecular motors. Such a mechanism can enable a neuron to discriminate between distances as close as 10% of total axon length. The model provides insights on retrograde injury signaling in neurons, including the biological relevance of the mechanism over different scales of nerves and organisms. Moreover, if similar mechanisms function in synapse to nucleus signaling in uninjured neurons, this could enable estimation of relative process lengths, thus guiding metabolic output from cell bodies to axons.
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Affiliation(s)
- Naaman Kam
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
| | - Yitzhak Pilpel
- Department of Molecular Genetics, Weizmann Institute of Science, Rehovot, Israel
| | - Mike Fainzilber
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, Israel
- * E-mail:
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Jordan BA, Kreutz MR. Nucleocytoplasmic protein shuttling: the direct route in synapse-to-nucleus signaling. Trends Neurosci 2009; 32:392-401. [PMID: 19524307 DOI: 10.1016/j.tins.2009.04.001] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2008] [Revised: 04/16/2009] [Accepted: 04/24/2009] [Indexed: 02/06/2023]
Abstract
In neurons multiple signaling pathways converge in the nucleus to regulate the expression of genes associated with long-term structural changes of synapto-dendritic input. Of pivotal importance for this type of transcriptional regulation is synapse-to-nucleus communication. Several studies suggest that the nuclear transport of proteins from synapses is involved in this signaling process, including evidence that synapses contain proteins with nuclear localization sequences and components of the nuclear import machinery. Here, we review the evidence for synapse-to-nucleus signaling by means of retrograde transport of proteins from distal processes. We discuss the mechanisms involved in their translocation and their role in the control of nuclear gene expression. Finally, we summarize the current thinking regarding the functional implications of nuclear signaling and address open questions in this evolving area of neuroscience.
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Affiliation(s)
- Bryen A Jordan
- Albert Einstein College of Medicine, Dominick P. Purpura Department of Neuroscience, Bronx, NY 10461, USA
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30
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Kermorgant S, Parker PJ. Receptor trafficking controls weak signal delivery: a strategy used by c-Met for STAT3 nuclear accumulation. ACTA ACUST UNITED AC 2008; 182:855-63. [PMID: 18779368 PMCID: PMC2528569 DOI: 10.1083/jcb.200806076] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
C-Met, the receptor of hepatocyte growth factor (HGF), through overexpression or mutation, is a major protooncogene that provides an attractive molecular target for cancer therapy. HGF/c-Met-induced tumorigenesis is dependent, in part, on the transcription factor and oncogene signal transducer and activator of transcription 3 (STAT3), which is believed to be activated by the receptor at the plasma membrane and then to travel to the nucleus where it acts. We demonstrate that although the robust signal to STAT3 elicited from the cytokine oncostatin-M does indeed support this mechanism of STAT3 action, for the weaker STAT3 signal emanating from c-Met, the activated receptor itself needs to be delivered to a perinuclear endosomal compartment to sustain phosphorylated STAT3 in the nucleus. This is signal specific because c-Met-induced extracellular signal-regulated kinase nuclear accumulation does not require receptor trafficking to the perinuclear compartment. This response is triggered from peripheral endosomes. Thus, control of growth factor receptor traffic determines the nature of the signal output, providing novel opportunities for intervention.
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Affiliation(s)
- Stéphanie Kermorgant
- Department of Tumour Biology, Cancer Research UK Clinical Centre, Bart's and the London Queen Mary's School of Medicine and Dentistry, London EC1M 6BQ, England, UK
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31
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Geldner N, Robatzek S. Plant receptors go endosomal: a moving view on signal transduction. PLANT PHYSIOLOGY 2008; 147:1565-74. [PMID: 18678748 PMCID: PMC2492600 DOI: 10.1104/pp.108.120287] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Accepted: 05/07/2008] [Indexed: 05/17/2023]
Affiliation(s)
- Niko Geldner
- Department of Plant Molecular Biology, University of Lausanne, 1015 Lausanne, Switzerland.
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32
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Sehgal PB. Paradigm shifts in the cell biology of STAT signaling. Semin Cell Dev Biol 2008; 19:329-40. [PMID: 18691663 DOI: 10.1016/j.semcdb.2008.07.003] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Revised: 07/15/2008] [Accepted: 07/17/2008] [Indexed: 01/25/2023]
Abstract
In recent years several of the key tenets of the original cytokine-STAT-signaling paradigm had to be revised. First, the notion that nonphosphorylated "inactive" STATs are present in the cytoplasm as free monomers which dimerized only subsequent to Tyr-phosphorylation has been replaced by the understanding that nonphosphorylated STATs in the cytoplasm exist largely as dimers and high molecular mass "statosome" complexes. Second, the notion that phosphorylation, either of Tyr or Ser residues or both, in STAT species is required for transcriptional activation has been replaced by the realization that nonphosphorylated STATs can be transcriptionally active albeit with respect to sets of target genes distinct from phosphorylated STATs. Third, the notion that it is the activation by phosphorylation of STATs at the plasma membrane that then leads to their import into the nucleus has been replaced by the recognition that even nonphosphorylated STATs shuttle between the cytoplasm and nucleus at all times in a constitutive manner. Fourth, the notion that the trans-cytoplasmic transit of STATs from the plasma membrane to the nuclear import machinery takes place exclusively as a free cytosolic process has been replaced by the understanding that at least a portion of this trans-cytoplasmic transit is mediated via membrane-associated caveolar and endocytic trafficking (the "signaling endosome" hypothesis). Fifth, the targeting and sequestration of activated STAT3 to long-lived endosomes in the cytoplasm requires consideration of STAT3-mediated "signal transduction" from the plasma membrane to cytoplasmic membrane destinations potentially for function(s) in the cytoplasm. Indeed, in tissue sections many discrete histologic cell types display PY-STAT3 almost exclusively in the cytoplasm with little, if any, in the nucleus. New challenges include determining the structural bases for the recruitment of nonphosphorylated dimeric STAT species to the cytosolic face of membranes including at the cytoplasmic tails of respective receptor complexes, the conformational changes subsequent to phosphorylation and the structural bases for the targeting and functions of STAT proteins within the cytoplasm per se.
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Affiliation(s)
- Pravin B Sehgal
- Department of Cell Biology & Anatomy, New York Medical College, Valhalla, NY 10595, United States.
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33
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Rajan SS, Liu HY, Vu TQ. Ligand-bound quantum dot probes for studying the molecular scale dynamics of receptor endocytic trafficking in live cells. ACS NANO 2008; 2:1153-1166. [PMID: 19206333 DOI: 10.1021/nn700399e] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Endocytic receptor trafficking is a complex, dynamic process underlying fundamental cell function. An integrated understanding of endocytosis at the level of single or small numbers of ligand bound-receptor complexes inside live cells is currently hampered by technical limitations. Here, we develop and test ligand nerve growth factor-bound quantum dot (NGF-QD) bioconjugates for imaging discrete receptor endocytic events inside live NGF-responsive PC12 cells. Using single particle tracking, QD hybrid gel coimmunoprecipitation, and immuno-colocalization, we illustrate and validate the use of QD-receptor complexes for imaging receptor trafficking at synchronized time points after QD-ligand-receptor binding and internalization (t = 15-150 min). The unique value of these probes is illustrated by new dynamic observations: (1) that endocytosis proceeds at strikingly regulated fashion, and (2) that diffusive and active forms of transport inside cells are rapid and efficient. QDs are powerful intracellular probes that can provide biologists with new capabilities and fresh insight for studying endocytic receptor signaling events, in real time, and at the resolution of single or small numbers of receptors in live cells.
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Affiliation(s)
- Sujata Sundara Rajan
- Department of Biomedical Engineering, Oregon Health & Science University, 3303 SW Bond Avenue, 13B, Portland, Oregon 97239, USA
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Zhou P, Porcionatto M, Pilapil M, Chen Y, Choi Y, Tolias KF, Bikoff JB, Hong EJ, Greenberg ME, Segal RA. Polarized signaling endosomes coordinate BDNF-induced chemotaxis of cerebellar precursors. Neuron 2007; 55:53-68. [PMID: 17610817 PMCID: PMC2661852 DOI: 10.1016/j.neuron.2007.05.030] [Citation(s) in RCA: 128] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2006] [Revised: 11/08/2006] [Accepted: 05/31/2007] [Indexed: 01/15/2023]
Abstract
During development, neural precursors migrate in response to positional cues such as growth factor gradients. However, the mechanisms that enable precursors to sense and respond to such gradients are poorly understood. Here we show that cerebellar granule cell precursors (GCPs) migrate along a gradient of brain-derived neurotrophic factor (BDNF), and we demonstrate that vesicle trafficking is critical for this chemotactic process. Activation of TrkB, the BDNF receptor, stimulates GCPs to secrete BDNF, thereby amplifying the ambient gradient. The BDNF gradient stimulates endocytosis of TrkB and associated signaling molecules, causing asymmetric accumulation of signaling endosomes at the subcellular location where BDNF concentration is maximal. Thus, regulated BDNF exocytosis and TrkB endocytosis enable precursors to polarize and migrate in a directed fashion along a shallow BDNF gradient.
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Affiliation(s)
- Pengcheng Zhou
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Department of Neurobiology, Harvard Medical School
| | - Marimelia Porcionatto
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Department of Neurobiology, Harvard Medical School
| | - Mariecel Pilapil
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Department of Neurobiology, Harvard Medical School
| | - Yicheng Chen
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Department of Neurobiology, Harvard Medical School
| | - Yoojin Choi
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Department of Neurobiology, Harvard Medical School
| | - Kimberley F. Tolias
- Division of Neuroscience, Children’s Hospital Boston and Department of Neurobiology, Harvard Medical School
| | - Jay B. Bikoff
- Division of Neuroscience, Children’s Hospital Boston and Department of Neurobiology, Harvard Medical School
| | - Elizabeth J. Hong
- Division of Neuroscience, Children’s Hospital Boston and Department of Neurobiology, Harvard Medical School
| | - Michael E. Greenberg
- Division of Neuroscience, Children’s Hospital Boston and Department of Neurobiology, Harvard Medical School
| | - Rosalind A. Segal
- Department of Pediatric Oncology, Dana-Farber Cancer Institute and Department of Neurobiology, Harvard Medical School
- To whom correspondence should be addressed: Rosalind A. Segal, Department of Pediatric Oncology, Dana-Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, 617-632-4737, 617-632-2085,
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35
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Abstract
Fungi invade substrates, such as host tissues, through hyphal tip growth. This article focuses on the corn smut fungus Ustilago maydis, in which tip growth and pathogenicity involve apical endocytic recycling by early endosomes. These organelles rapidly move bi-directionally along microtubules and this movement is mediated by opposing molecular motors. This motility seems to be essential for extended hyphal growth, possibly because it focuses the endocytic machinery at the hyphal tip and mediates communication between the tip and the sub-apical nucleus.
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Affiliation(s)
- Gero Steinberg
- Max-Planck-Institut für terrestrische Mikrobiologie, Karl-von-Frisch Strabe D-35043 Marburg, Germany.
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36
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Otis KO, Thompson KR, Martin KC. Importin-mediated nuclear transport in neurons. Curr Opin Neurobiol 2006; 16:329-35. [PMID: 16690311 DOI: 10.1016/j.conb.2006.05.001] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Accepted: 05/03/2006] [Indexed: 01/17/2023]
Abstract
The polarized morphology of neurons poses a particular challenge to intracellular signal transduction. Local signals generated at distal sites must be retrogradely transported to the nucleus to produce persistent changes in neuronal function. Such communication of signals between distal neuronal compartments and the nucleus occurs during axon guidance, synapse formation, synaptic plasticity and following neuronal injury. Recent studies have begun to delineate a role for the active nuclear import pathway in transporting signals from axons and dendrites to the nucleus. In this pathway, soluble cargo proteins are recognized by nuclear transport carriers, called importins, which mediate their translocation from the cytoplasm into the nucleus. In neurons, importins might serve an additional function by carrying signals from distal sites to the soma.
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Affiliation(s)
- Klara Olofsdotter Otis
- University of California, Los Angeles, Gonda Research Building 3506C, 695 Charles Young Drive South, Los Angeles, CA 90095-1761, USA
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37
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Mikenberg I, Widera D, Kaus A, Kaltschmidt B, Kaltschmidt C. TNF-alpha mediated transport of NF-kappaB to the nucleus is independent of the cytoskeleton-based transport system in non-neuronal cells. Eur J Cell Biol 2006; 85:529-36. [PMID: 16584809 DOI: 10.1016/j.ejcb.2006.02.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2006] [Revised: 02/09/2006] [Accepted: 02/13/2006] [Indexed: 11/25/2022] Open
Abstract
In unstimulated cells, proteins of the nuclear factor kappaB (NF-kappaB) transcription factor family are sequestered in the cytoplasm through interactions with IkappaB inhibitor proteins. Tumor necrosis factor alpha (TNF-alpha) activates the degradation of IkappaB-alpha and the nuclear import of cytoplasmic NF-kappaB. Nuclear localization of numerous cellular proteins is mediated by the ability of the cytoskeleton, usually microtubules, to direct their perinuclear accumulation. In a former study we have shown that activated NF-kappaB rapidly moves from distal processes in neurons towards the nucleus. The fast transport rate suggests the involvement of motor proteins in the transport of NF-kappaB. Here we address the question how NF-kappaB arrives at the nuclear membrane before import in non-neuronal cells, i.e., by diffusion alone or with the help of active transport mechanisms. Using confocal microscopy imaging and analysis of nuclear protein extracts, we show that NF-kappaB movement through the cytoplasm to the nucleus is independent of the cytoskeleton, in the three cell lines investigated here. Additionally we demonstrate that NF-kappaB p65 is not associated with the dynein/dynactin molecular motor complex. We propose that cells utilize two distinct mechanisms of NF-kappaB transport: (1) signaling via diffusion over short distances in non-neuronal cells and (2) transport via motor proteins that move along the cytoskeleton in neuronal processes where the distances between sites of NF-kappaB activation and nucleus can be vast.
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Affiliation(s)
- Ilja Mikenberg
- Institut für Neurobiochemie Universität Witten/Herdecke, Stockumer Str. 10, D-58448 Witten, Germany
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38
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Shah M, Patel K, Mukhopadhyay S, Xu F, Guo G, Sehgal PB. Membrane-associated STAT3 and PY-STAT3 in the Cytoplasm. J Biol Chem 2006; 281:7302-8. [PMID: 16407171 DOI: 10.1074/jbc.m508527200] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Signal transduction from the plasma membrane to the nucleus by STAT proteins is widely represented as exclusively a soluble cytosolic process. Using cell-fractionation methods, we observed that approximately 5% of cytoplasmic STAT3 was constitutively associated with the purified early endosome (EE) fraction in human Hep3B liver cells. By 15-30 min after interleukin-6 (IL-6) treatment, up to two-thirds of cytoplasmic Tyr-phosphorylated STAT3 can be associated with the purified early endosome fraction (Rab-5-, EEA1-, transferrin receptor-, and clathrin-positive fraction). Electron microscopy, immunofluorescence, and detergent dissection approaches confirmed the association of STAT3 and PY-STAT3 with early endosomes. STAT3 was constitutively associated with clathrin heavy chain in membrane and in the 1- to 2-MDa cytosolic complexes. The membrane association was dynamic in that, within 15 min of treatment with the vicinal-thiol cross-linker phenylarsine oxide, there was a dramatic increase in bulk STAT3 association with sedimentable membranes. The functional contribution of PY-STAT3 association with the endocytic pathway was evaluated in transient transfection assays using IL-6-inducible STAT3-reporter-luciferase constructs and selective regulators of this pathway. STAT3-transcriptional activation was inhibited by expression constructs for dominant negative dynamin K44A, epsin 2a, amphiphysin A1, and clathrin light chain but enhanced by that for the active dynamin species MxA. Taken together, these studies emphasize the contribution of the endocytic pathway to productive IL-6/STAT3 signaling.
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Affiliation(s)
- Mehul Shah
- Department of Cell Biology and Anatomy, New York Medical College, Valhalla, NY 10595, USA
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