1
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Gray ALH, Sawaya MR, Acharyya D, Lou J, Edington EM, Best MD, Prosser RA, Eisenberg DS, Do TD. Atomic view of an amyloid dodecamer exhibiting selective cellular toxic vulnerability in acute brain slices. Protein Sci 2022; 31:716-727. [PMID: 34954854 PMCID: PMC8862425 DOI: 10.1002/pro.4268] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 12/14/2021] [Accepted: 12/23/2021] [Indexed: 12/16/2022]
Abstract
Atomic structures of amyloid oligomers that capture the neurodegenerative disease pathology are essential to understand disease-state causes and finding cures. Here we investigate the G6W mutation of the cytotoxic, hexameric amyloid model KV11. The mutation results into an asymmetric dodecamer composed of a pair of 30° twisted antiparallel β-sheets. The complete break between adjacent β-strands is unprecedented among amyloid fibril crystal structures and supports that our structure is an oligomer. The poor shape complementarity between mated sheets reveals an interior channel for binding lipids, suggesting that the toxicity may be due to a perturbation of lipid transport rather than a direct disruption of membrane integrity. Viability assays on mouse suprachiasmatic nucleus, anterior hypothalamus, and cerebral cortex demonstrated selective regional vulnerability consistent with Alzheimer's disease. Neuropeptides released from the brain slices may provide clues to how G6W initiates cellular injury.
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Affiliation(s)
- Amber L. H. Gray
- Department of ChemistryUniversity of TennesseeKnoxvilleTennesseeUSA
| | - Michael R. Sawaya
- HHMIUniversity of CaliforniaLos AngelesCaliforniaUSA,Department of Chemistry and BiochemistryUniversity of CaliforniaLos AngelesCaliforniaUSA,Department of Biological ChemistryUniversity of CaliforniaLos AngelesCaliforniaUSA,Molecular Biology InstituteUniversity of CaliforniaLos AngelesCaliforniaUSA,Department of Energy Institute for Genomics and ProteomicsUniversity of CaliforniaLos AngelesCaliforniaUSA
| | - Debalina Acharyya
- Department of Biochemistry & Cellular and Molecular BiologyUniversity of TennesseeKnoxvilleTennesseeUSA
| | - Jinchao Lou
- Department of ChemistryUniversity of TennesseeKnoxvilleTennesseeUSA
| | | | - Michael D. Best
- Department of ChemistryUniversity of TennesseeKnoxvilleTennesseeUSA
| | - Rebecca A. Prosser
- Department of Biochemistry & Cellular and Molecular BiologyUniversity of TennesseeKnoxvilleTennesseeUSA
| | - David S. Eisenberg
- HHMIUniversity of CaliforniaLos AngelesCaliforniaUSA,Department of Chemistry and BiochemistryUniversity of CaliforniaLos AngelesCaliforniaUSA,Department of Biological ChemistryUniversity of CaliforniaLos AngelesCaliforniaUSA,Molecular Biology InstituteUniversity of CaliforniaLos AngelesCaliforniaUSA,Department of Energy Institute for Genomics and ProteomicsUniversity of CaliforniaLos AngelesCaliforniaUSA
| | - Thanh D. Do
- Department of ChemistryUniversity of TennesseeKnoxvilleTennesseeUSA
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2
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Gillette MU, Mitchell JW. Electrophysiology of the Suprachiasmatic Nucleus: Single-Unit Recording. Methods Mol Biol 2022; 2482:181-189. [PMID: 35610427 DOI: 10.1007/978-1-0716-2249-0_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Oscillatory output from the suprachiasmatic nuclei (SCN) of the hypothalamus communicates time-of-day information to the brain and body. The SCN's intrinsic ~24-h rhythm can be measured in the neuronal firing rate both in vivo and in vitro, where it continues unperturbed. This robust reporter of endogenous physiology in the SCN brain slice can be widely used to study dynamic changes in SCN physiology, its changing sensitivity to phase-altering signals, and underlying mechanisms. To provide relevant and reproducible data, care must be taken to ensure health of the SCN brain slice. The methods detailed here have been proven to produce healthy, long-lived brain slices.
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Affiliation(s)
- Martha U Gillette
- Department of Cell and Developmental Biology and Neuroscience Program, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA.
| | - Jennifer W Mitchell
- Department of Cell and Developmental Biology and Neuroscience Program, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL, USA
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3
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Atkins N, Ren S, Hatcher N, Burgoon PW, Mitchell JW, Sweedler JV, Gillette MU. Functional Peptidomics: Stimulus- and Time-of-Day-Specific Peptide Release in the Mammalian Circadian Clock. ACS Chem Neurosci 2018; 9:2001-2008. [PMID: 29901982 DOI: 10.1021/acschemneuro.8b00089] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
Daily oscillations of brain and body states are under complex temporal modulation by environmental light and the hypothalamic suprachiasmatic nucleus (SCN), the master circadian clock. To better understand mediators of differential temporal modulation, we characterize neuropeptide releasate profiles by nonselective capture of secreted neuropeptides in an optic nerve horizontal SCN brain slice model. Releasates are collected following electrophysiological stimulation of the optic nerve/retinohypothalamic tract under conditions that alter the phase of the SCN activity state. Secreted neuropeptides are identified by intact mass via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). We found time-of-day-specific suites of peptides released downstream of optic nerve stimulation. Peptide release was modified differentially with respect to time-of-day by stimulus parameters and by inhibitors of glutamatergic or PACAPergic neurotransmission. The results suggest that SCN physiology is modulated by differential peptide release of both known and unexpected peptides that communicate time-of-day-specific photic signals via previously unreported neuropeptide signatures.
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4
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Khan AM, Grant AH, Martinez A, Burns GAPC, Thatcher BS, Anekonda VT, Thompson BW, Roberts ZS, Moralejo DH, Blevins JE. Mapping Molecular Datasets Back to the Brain Regions They are Extracted from: Remembering the Native Countries of Hypothalamic Expatriates and Refugees. ADVANCES IN NEUROBIOLOGY 2018; 21:101-193. [PMID: 30334222 PMCID: PMC6310046 DOI: 10.1007/978-3-319-94593-4_6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
This article focuses on approaches to link transcriptomic, proteomic, and peptidomic datasets mined from brain tissue to the original locations within the brain that they are derived from using digital atlas mapping techniques. We use, as an example, the transcriptomic, proteomic and peptidomic analyses conducted in the mammalian hypothalamus. Following a brief historical overview, we highlight studies that have mined biochemical and molecular information from the hypothalamus and then lay out a strategy for how these data can be linked spatially to the mapped locations in a canonical brain atlas where the data come from, thereby allowing researchers to integrate these data with other datasets across multiple scales. A key methodology that enables atlas-based mapping of extracted datasets-laser-capture microdissection-is discussed in detail, with a view of how this technology is a bridge between systems biology and systems neuroscience.
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Affiliation(s)
- Arshad M Khan
- UTEP Systems Neuroscience Laboratory, University of Texas at El Paso, El Paso, TX, USA.
- Department of Biological Sciences, University of Texas at El Paso, El Paso, TX, USA.
- Border Biomedical Research Center, University of Texas at El Paso, El Paso, TX, USA.
| | - Alice H Grant
- UTEP Systems Neuroscience Laboratory, University of Texas at El Paso, El Paso, TX, USA
- Department of Biological Sciences, University of Texas at El Paso, El Paso, TX, USA
- Graduate Program in Pathobiology, University of Texas at El Paso, El Paso, TX, USA
| | - Anais Martinez
- UTEP Systems Neuroscience Laboratory, University of Texas at El Paso, El Paso, TX, USA
- Department of Biological Sciences, University of Texas at El Paso, El Paso, TX, USA
- Graduate Program in Pathobiology, University of Texas at El Paso, El Paso, TX, USA
| | - Gully A P C Burns
- Information Sciences Institute, Viterbi School of Engineering, University of Southern California, Marina del Rey, CA, USA
| | - Brendan S Thatcher
- VA Puget Sound Health Care System, Office of Research and Development Medical Research Service, Department of Veterans Affairs Medical Center, Seattle, WA, USA
| | - Vishwanath T Anekonda
- VA Puget Sound Health Care System, Office of Research and Development Medical Research Service, Department of Veterans Affairs Medical Center, Seattle, WA, USA
| | - Benjamin W Thompson
- VA Puget Sound Health Care System, Office of Research and Development Medical Research Service, Department of Veterans Affairs Medical Center, Seattle, WA, USA
| | - Zachary S Roberts
- VA Puget Sound Health Care System, Office of Research and Development Medical Research Service, Department of Veterans Affairs Medical Center, Seattle, WA, USA
| | - Daniel H Moralejo
- Division of Neonatology, Department of Pediatrics, University of Washington School of Medicine, Seattle, WA, USA
| | - James E Blevins
- VA Puget Sound Health Care System, Office of Research and Development Medical Research Service, Department of Veterans Affairs Medical Center, Seattle, WA, USA
- Division of Metabolism, Endocrinology, and Nutrition, Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA
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5
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Matus-Ortega ME, Leff Gelman P, Calva-Nieves JC, Flores-Zamora A, Salazar-Juárez A, Torner-Aguilar CA, Gamba G, De Los Heros P, Peng B, Pintar JE, Gompf HS, Allen CN, Antón-Palma B. Mexneurin is a novel precursor of peptides in the central nervous system of rodents. FEBS Lett 2017; 591:1627-1636. [PMID: 28504339 DOI: 10.1002/1873-3468.12679] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Revised: 04/19/2017] [Accepted: 05/10/2017] [Indexed: 12/29/2022]
Abstract
Endomorphins (EMs) have been proposed as the endogenous ligand agonists of the μ-opioid receptor; however, no propeptide precursor protein for EMs has been identified. Here, to identify the presumed precursor of EMs, we designed an immunoscreening assay using specific affinity-purified rabbit antisera raised against synthetic EMs in a whole-mouse brain cDNA library. Following this approach, we identify a DNA sequence encoding a protein precursor, which we name proMexneurin, that contains three different peptide sequences: Mexneurin-1 (an EM-like peptide), Mexneurin-2, and Mexneurin-3, a peptide which appears to be unrelated to EMs. RT-PCR analysis and in situ hybridization reveal a widespread distribution of proMexneurin mRNA throughout the mouse brain. Both Mexneurin-1 and Mexneurin-3 peptides display biological activities in the mouse CNS.
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Affiliation(s)
- Maura E Matus-Ortega
- Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Ciudad de México, México
| | | | - Juan C Calva-Nieves
- Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Ciudad de México, México
| | - Anabel Flores-Zamora
- Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Ciudad de México, México
| | | | | | - Gerardo Gamba
- Molecular Physiology Unit, Instituto Nacional de Ciencias Médicas y Nutrición Salvador Zubirán and Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Paola De Los Heros
- Dirección de Investigación, Facultad de Medicina, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Bonnie Peng
- Department of Neuroscience and Cell Biology, Rutgers Biomedical and Health Sciences, Newark, NJ, USA
| | - John E Pintar
- Department of Neuroscience and Cell Biology, Rutgers Biomedical and Health Sciences, Newark, NJ, USA
| | - Heinrich S Gompf
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, USA
| | - Charles N Allen
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, OR, USA
| | - Benito Antón-Palma
- Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Ciudad de México, México
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6
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Romanova EV, Sweedler JV. Peptidomics for the discovery and characterization of neuropeptides and hormones. Trends Pharmacol Sci 2015; 36:579-86. [PMID: 26143240 DOI: 10.1016/j.tips.2015.05.009] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 05/28/2015] [Accepted: 05/29/2015] [Indexed: 12/31/2022]
Abstract
The discovery of neuropeptides as signaling molecules with paracrine or hormonal regulatory functions has led to trailblazing advances in physiology and fostered the characterization of numerous neuropeptide-binding G protein-coupled receptors (GPCRs) as potential drug targets. The impact on human health has been tremendous: approximately 30% of commercial drugs act via the GPCR pathway. However, about 25% of the GPCRs encoded by the mammalian genome still lack their pharmacological identity. Searching for the orphan GPCR endogenous ligands that are likely to be neuropeptides has proved to be a formidable task. Here we describe the mass spectrometry (MS)-based technologies and experimental strategies that have been successful in achieving high-throughput characterization of endogenous peptides in nervous and endocrine systems.
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Affiliation(s)
- Elena V Romanova
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, IL 61801, USA; Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Jonathan V Sweedler
- Department of Chemistry, University of Illinois at Urbana-Champaign, 600 S. Mathews Avenue, Urbana, IL 61801, USA; Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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7
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Lin LL, Huang HC, Juan HF. Circadian systems biology in Metazoa. Brief Bioinform 2015; 16:1008-24. [PMID: 25758249 DOI: 10.1093/bib/bbv006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2014] [Indexed: 12/30/2022] Open
Abstract
Systems biology, which can be defined as integrative biology, comprises multistage processes that can be used to understand components of complex biological systems of living organisms and provides hierarchical information to decoding life. Using systems biology approaches such as genomics, transcriptomics and proteomics, it is now possible to delineate more complicated interactions between circadian control systems and diseases. The circadian rhythm is a multiscale phenomenon existing within the body that influences numerous physiological activities such as changes in gene expression, protein turnover, metabolism and human behavior. In this review, we describe the relationships between the circadian control system and its related genes or proteins, and circadian rhythm disorders in systems biology studies. To maintain and modulate circadian oscillation, cells possess elaborative feedback loops composed of circadian core proteins that regulate the expression of other genes through their transcriptional activities. The disruption of these rhythms has been reported to be associated with diseases such as arrhythmia, obesity, insulin resistance, carcinogenesis and disruptions in natural oscillations in the control of cell growth. This review demonstrates that lifestyle is considered as a fundamental factor that modifies circadian rhythm, and the development of dysfunctions and diseases could be regulated by an underlying expression network with multiple circadian-associated signals.
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8
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Southey BR, Lee JE, Zamdborg L, Atkins N, Mitchell JW, Li M, Gillette MU, Kelleher NL, Sweedler JV. Comparing label-free quantitative peptidomics approaches to characterize diurnal variation of peptides in the rat suprachiasmatic nucleus. Anal Chem 2013; 86:443-52. [PMID: 24313826 PMCID: PMC3886391 DOI: 10.1021/ac4023378] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
![]()
Mammalian
circadian rhythm is maintained by the suprachiasmatic nucleus (SCN)
via an intricate set of neuropeptides and other signaling molecules.
In this work, peptidomic analyses from two times of day were examined
to characterize variation in SCN peptides using three different label-free
quantitation approaches: spectral count, spectra index and SIEVE.
Of the 448 identified peptides, 207 peptides were analyzed by two
label-free methods, spectral count and spectral index. There were
24 peptides with significant (adjusted p-value <
0.01) differential peptide abundances between daytime and nighttime,
including multiple peptides derived from secretogranin II, cocaine
and amphetamine regulated transcript, and proprotein convertase subtilisin/kexin
type 1 inhibitor. Interestingly, more peptides were analyzable and
had significantly different abundances between the two time points
using the spectral count and spectral index methods than with a prior
analysis using the SIEVE method with the same data. The results of
this study reveal the importance of using the appropriate data analysis
approaches for label-free relative quantitation of peptides. The detection
of significant changes in so rich a set of neuropeptides reflects
the dynamic nature of the SCN and the number of influences such as
feeding behavior on circadian rhythm. Using spectral count and spectral
index, peptide level changes are correlated to time of day, suggesting
their key role in circadian function.
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Affiliation(s)
- Bruce R Southey
- Department of Animal Sciences, ‡Department of Chemistry, §Institute for Genomic Biology, ∥Neuroscience Program, ⊥Department of Cell and Developmental Biology, and ¶Beckman Institute, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, United States
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9
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Craft GE, Chen A, Nairn AC. Recent advances in quantitative neuroproteomics. Methods 2013; 61:186-218. [PMID: 23623823 PMCID: PMC3891841 DOI: 10.1016/j.ymeth.2013.04.008] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2012] [Revised: 03/29/2013] [Accepted: 04/13/2013] [Indexed: 01/07/2023] Open
Abstract
The field of proteomics is undergoing rapid development in a number of different areas including improvements in mass spectrometric platforms, peptide identification algorithms and bioinformatics. In particular, new and/or improved approaches have established robust methods that not only allow for in-depth and accurate peptide and protein identification and modification, but also allow for sensitive measurement of relative or absolute quantitation. These methods are beginning to be applied to the area of neuroproteomics, but the central nervous system poses many specific challenges in terms of quantitative proteomics, given the large number of different neuronal cell types that are intermixed and that exhibit distinct patterns of gene and protein expression. This review highlights the recent advances that have been made in quantitative neuroproteomics, with a focus on work published over the last five years that applies emerging methods to normal brain function as well as to various neuropsychiatric disorders including schizophrenia and drug addiction as well as of neurodegenerative diseases including Parkinson's disease and Alzheimer's disease. While older methods such as two-dimensional polyacrylamide electrophoresis continued to be used, a variety of more in-depth MS-based approaches including both label (ICAT, iTRAQ, TMT, SILAC, SILAM), label-free (label-free, MRM, SWATH) and absolute quantification methods, are rapidly being applied to neurobiological investigations of normal and diseased brain tissue as well as of cerebrospinal fluid (CSF). While the biological implications of many of these studies remain to be clearly established, that there is a clear need for standardization of experimental design and data analysis, and that the analysis of protein changes in specific neuronal cell types in the central nervous system remains a serious challenge, it appears that the quality and depth of the more recent quantitative proteomics studies is beginning to shed light on a number of aspects of neuroscience that relates to normal brain function as well as of the changes in protein expression and regulation that occurs in neuropsychiatric and neurodegenerative disorders.
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Affiliation(s)
- George E Craft
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, 06508
| | - Anshu Chen
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, 06508
| | - Angus C Nairn
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, 06508
- Yale/NIDA Neuroproteomics Center, Yale University School of Medicine, New Haven, CT, 06508
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10
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Lee JE, Zamdborg L, Southey BR, Atkins N, Mitchell JW, Li M, Gillette MU, Kelleher NL, Sweedler JV. Quantitative peptidomics for discovery of circadian-related peptides from the rat suprachiasmatic nucleus. J Proteome Res 2013; 12:585-93. [PMID: 23256577 DOI: 10.1021/pr300605p] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
In mammals the suprachiasmatic nucleus (SCN), the master circadian clock, is sensitive to light input via the optic chiasm and synchronizes many daily biological rhythms. Here we explore variations in the expression levels of neuropeptides present in the SCN of rats using a label-free quantification approach that is based on integrating peak intensities between daytime, Zeitgeber time (ZT) 6, and nighttime, ZT 18. From nine analyses comparing the levels between these two time points, 10 endogenous peptides derived from eight prohormones exhibited significant differences in their expression levels (adjusted p-value <0.05). Of these, seven peptides derived from six prohormones, including GRP, PACAP, and CART, exhibited ≥ 30% increases at ZT 18, and the VGRPEWWMDYQ peptide derived from proenkephalin A showed a >50% increase at nighttime. Several endogenous peptides showing statistically significant changes in this study have not been previously reported to alter their levels as a function of time of day, nor have they been implicated in prior functional SCN studies. This information on peptide expression changes serves as a resource for discovering unknown peptide regulators that affect circadian rhythms in the SCN.
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Affiliation(s)
- Ji Eun Lee
- Department of Chemistry, Beckman Institute, University of Illinois at Urbana-Champaign , Urbana, Illinois 61801, USA
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11
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Millet LJ, Gillette MU. New perspectives on neuronal development via microfluidic environments. Trends Neurosci 2012; 35:752-61. [PMID: 23031246 DOI: 10.1016/j.tins.2012.09.001] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Revised: 08/18/2012] [Accepted: 09/06/2012] [Indexed: 11/28/2022]
Abstract
Understanding the signals that guide neuronal development and direct formation of axons, dendrites, and synapses during wiring of the brain is a fundamental challenge in developmental neuroscience. Discovery of how local signals shape developing neurons has been impeded by the inability of conventional culture methods to interrogate microenvironments of complex neuronal cytoarchitectures, where different subdomains encounter distinct chemical, physical, and fluidic features. Microfabrication techniques are facilitating the creation of microenvironments tailored to neuronal structures and subdomains with unprecedented access and control. The design, fabrication, and properties of microfluidic devices offer significant advantages for addressing unresolved issues of neuronal development. These high-resolution approaches are poised to contribute new insights into mechanisms for restoring neuronal function and connectivity compromised by injury, stress, and neurodegeneration.
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Affiliation(s)
- Larry J Millet
- Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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12
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Extracellular identification of a processed type II ComR/ComS pheromone of Streptococcus mutans. J Bacteriol 2012; 194:3781-8. [PMID: 22609914 DOI: 10.1128/jb.00624-12] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The competence-stimulating peptide (CSP) and the sigX-inducing peptide (XIP) are known to induce Streptococcus mutans competence for genetic transformation. For both pheromones, direct identification of the native peptides has not been accomplished. The fact that extracellular XIP activity was recently observed in a chemically defined medium devoid of peptides, as mentioned in an accompanying paper (K. Desai, L. Mashburn-Warren, M. J. Federle, and D. A. Morrison, J. Bacteriol. 194:3774-3780, 2012), provided ideal conditions for native XIP identification. To search for the XIP identity, culture supernatants were filtered to select for peptides of less than 3 kDa, followed by C(18) extraction. One peptide, not detected in the supernatant of a comS deletion mutant, was identified by tandem mass spectrometry (MS/MS) fragmentation as identical to the ComS C-terminal sequence GLDWWSL. ComS processing did not require Eep, a peptidase involved in processing or import of bacterial small hydrophobic peptides, since eep deletion had no inhibitory effect on XIP production or on synthetic XIP response. We investigated whether extracellular CSP was also produced. A reporter assay for CSP activity detection, as well as MS analysis of supernatants, revealed that CSP was not present at detectable levels. In addition, a mutant with deletion of the CSP-encoding gene comC produced endogenous XIP levels similar to those of a nondeletion mutant. The results indicate that XIP pheromone production is a natural phenomenon that may occur in the absence of natural CSP pheromone activity and that the heptapeptide GLDWWSL is an extracellular processed form of ComS, possibly the active XIP pheromone. This is the first report of direct identification of a ComR/ComS pheromone.
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13
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Murphy D, Konopacka A, Hindmarch C, Paton JFR, Sweedler JV, Gillette MU, Ueta Y, Grinevich V, Lozic M, Japundzic-Zigon N. The hypothalamic-neurohypophyseal system: from genome to physiology. J Neuroendocrinol 2012; 24:539-53. [PMID: 22448850 PMCID: PMC3315060 DOI: 10.1111/j.1365-2826.2011.02241.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The elucidation of the genomes of a large number of mammalian species has produced a huge amount of data on which to base physiological studies. These endeavours have also produced surprises, not least of which has been the revelation that the number of protein coding genes needed to make a mammal is only 22 333 (give or take). However, this small number belies an unanticipated complexity that has only recently been revealed as a result of genomic studies. This complexity is evident at a number of levels: (i) cis-regulatory sequences; (ii) noncoding and antisense mRNAs, most of which have no known function; (iii) alternative splicing that results in the generation of multiple, subtly different mature mRNAs from the precursor transcript encoded by a single gene; and (iv) post-translational processing and modification. In this review, we examine the steps being taken to decipher genome complexity in the context of gene expression, regulation and function in the hypothalamic-neurohypophyseal system (HNS). Five unique stories explain: (i) the use of transcriptomics to identify genes involved in the response to physiological (dehydration) and pathological (hypertension) cues; (ii) the use of mass spectrometry for single-cell level identification of biological active peptides in the HNS, and to measure in vitro release; (iii) the use of transgenic lines that express fusion transgenes enabling (by cross-breeding) the generation of double transgenic lines that can be used to study vasopressin (AVP) and oxytocin (OXT) neurones in the HNS, as well as their neuroanatomy, electrophysiology and activation upon exposure to any given stimulus; (iv) the use of viral vectors to demonstrate that somato-dendritically released AVP plays an important role in cardiovascular homeostasis by binding to V1a receptors on local somata and dendrites; and (v) the use of virally-mediated optogenetics to dissect the role of OXT and AVP in the modulation of a wide variety of behaviours.
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Affiliation(s)
- D Murphy
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, University of Bristol, Bristol, UK.
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14
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Lenco J, Lan R, Edwards N, Goldman R. MS/MS library facilitated MRM quantification of native peptides prepared by denaturing ultrafiltration. Proteome Sci 2012; 10:7. [PMID: 22304756 PMCID: PMC3331852 DOI: 10.1186/1477-5956-10-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Accepted: 02/04/2012] [Indexed: 12/18/2022] Open
Abstract
Naturally occurring native peptides provide important information about physiological states of an organism and its changes in disease conditions but protocols and methods for assessing their abundance are not well-developed. In this paper, we describe a simple procedure for the quantification of non-tryptic peptides in body fluids. The workflow includes an enrichment step followed by two-dimensional fractionation of native peptides and MS/MS data management facilitating the design and validation of LC- MRM MS assays. The added value of the workflow is demonstrated in the development of a triplex LC-MRM MS assay used for quantification of peptides potentially associated with the progression of liver disease to hepatocellular carcinoma.
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Affiliation(s)
- Juraj Lenco
- Georgetown University, Department of Oncology, Lombardi Comprehensive Cancer Center, 3970 Reservoir Rd NW, Washington, DC 20057, USA.
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