1
|
Karunanithi S, Brown IR. Heat shock response and homeostatic plasticity. Front Cell Neurosci 2015; 9:68. [PMID: 25814928 PMCID: PMC4357293 DOI: 10.3389/fncel.2015.00068] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 02/17/2015] [Indexed: 11/13/2022] Open
Abstract
Heat shock response and homeostatic plasticity are mechanisms that afford functional stability to cells in the face of stress. Each mechanism has been investigated independently, but the link between the two has not been extensively explored. We explore this link. The heat shock response enables cells to adapt to stresses such as high temperature, metabolic stress and reduced oxygen levels. This mechanism results from the production of heat shock proteins (HSPs) which maintain normal cellular functions by counteracting the misfolding of cellular proteins. Homeostatic plasticity enables neurons and their target cells to maintain their activity levels around their respective set points in the face of stress or disturbances. This mechanism results from the recruitment of adaptations at synaptic inputs, or at voltage-gated ion channels. In this perspective, we argue that heat shock triggers homeostatic plasticity through the production of HSPs. We also suggest that homeostatic plasticity is a form of neuroprotection.
Collapse
Affiliation(s)
- Shanker Karunanithi
- School of Medical Science, Griffith University QLD, Australia ; Menzies Health Institute of Queensland, Griffith University QLD, Australia
| | - Ian R Brown
- Department of Biological Sciences, Centre for the Neurobiology of Stress, University of Toronto Scarborough Toronto, ON, Canada
| |
Collapse
|
2
|
Temperature and neuronal circuit function: compensation, tuning and tolerance. Curr Opin Neurobiol 2012; 22:724-34. [DOI: 10.1016/j.conb.2012.01.008] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2012] [Revised: 01/18/2012] [Accepted: 01/19/2012] [Indexed: 01/24/2023]
|
3
|
Rodgers CI, Armstrong GAB, Robertson RM. Coma in response to environmental stress in the locust: a model for cortical spreading depression. JOURNAL OF INSECT PHYSIOLOGY 2010; 56:980-990. [PMID: 20361971 DOI: 10.1016/j.jinsphys.2010.03.030] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2010] [Revised: 03/19/2010] [Accepted: 03/22/2010] [Indexed: 05/29/2023]
Abstract
Spreading depression (SD) is an interesting and important phenomenon due to its role in mammalian pathologies such as migraine, seizures, and stroke. Until recently investigations of the mechanisms involved in SD have mostly utilized mammalian cortical tissue, however we have discovered that SD-like events occur in the CNS of an invertebrate model, Locusta migratoria. Locusts enter comas in response to stress during which neural and muscular systems shut down until the stress is removed, and this is believed to be an adaptive strategy to survive extreme environmental conditions. During stress-induced comas SD-like events occur in the locust metathoracic ganglion (MTG) that closely resemble cortical SD (CSD) in many respects, including mechanism of induction, extracellular potassium ion changes, and propagation in areas equivalent to mammalian grey matter. In this review we describe the generation of comas and the associated SD-like events in the locust, provide a description of the similarities to CSD, and show how they can be manipulated both by stress preconditioning and pharmacologically. We also suggest that locust SD-like events are adaptive by conserving energy and preventing cellular damage, and we provide a model for the mechanism of SD onset and recovery in the locust nervous system.
Collapse
Affiliation(s)
- Corinne I Rodgers
- Department of Biology, Queen's University, Biosciences Complex, Kingston, Ontario, Canada.
| | | | | |
Collapse
|
4
|
Klose MK, Boulianne GL, Robertson RM, Atwood HL. Role of ATP-dependent calcium regulation in modulation of Drosophila synaptic thermotolerance. J Neurophysiol 2009; 102:901-13. [PMID: 19474168 DOI: 10.1152/jn.91209.2008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Maintenance of synaptic transmission requires regulation of intracellular Ca(2+) in presynaptic nerve terminals; loss of this regulation at elevated temperatures may cause synaptic failure. Accordingly, we examined the thermosensitivity of presynaptic calcium regulation in Drosophila larval neuromuscular junctions, testing for effects of disrupting calcium clearance. Motor neurons were loaded with the ratiometric Ca(2+) indicator Fura-dextran to monitor calcium regulation as temperature increased. Block of the Na(+)/Ca(2+) exchanger or removal of extracellular Ca(2+) prevented the normal temperature-induced increase in resting calcium. Conversely, two treatments that interfered with Ca(2+) clearance-inactivation of the endoplasmic reticulum Ca(2+)-ATPase with thapsigargin and inhibition of the plasma membrane Ca(2+)-ATPase with high pH-significantly accelerated the temperature-induced rise in resting Ca(2+) concentration and reduced the thermotolerance of synaptic transmission. Disrupting Ca(2+)-ATPase function by interfering with energy production also facilitated the temperature-induced rise in resting [Ca(2+)] and reduced thermotolerance of synaptic transmission. Conversely, fortifying energy levels with extra intracellular ATP extended the operating temperature range of both synaptic transmission and Ca(2+) regulation. In each of these cases, Ca(2+) elevations evoked by an electrical stimulation of the nerve (evoked Ca(2+) responses) failed when resting Ca(2+) remained >e 200 nM for several minutes. Failure of synaptic function was correlated with the release of intracellular calcium stores, and we provide evidence suggesting that release from the mitochondria disrupts evoked calcium responses and synaptic transmission. Thus the thermal limit of synaptic transmission may be directly linked to the stability of ATP-dependent mechanisms that regulate intracellular ion concentrations in the nerve terminal.
Collapse
Affiliation(s)
- M K Klose
- Department of Physiology, University of Toronto, Toronto, Ontario, Canada.
| | | | | | | |
Collapse
|
5
|
Money TGA, Rodgers CI, McGregor SMK, Robertson RM. Loss of potassium homeostasis underlies hyperthermic conduction failure in control and preconditioned locusts. J Neurophysiol 2009; 102:285-93. [PMID: 19386751 DOI: 10.1152/jn.91174.2008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
At extreme temperature, neurons cease to function appropriately. Prior exposure to a heat stress (heat shock [HS]) can extend the temperature range for action potential conduction in the axon, but how this occurs is not well understood. Here we use electrophysiological recordings from the axon of a locust visual interneuron, the descending contralateral movement detector (DCMD), to examine what physiological changes result in conduction failure and what modifications allow for the observed plasticity following HS. We show that at high temperature, conduction failure in the DCMD occurred preferentially where the axon passes through the thoracic ganglia rather than in the connective. Although the membrane potential hyperpolarized with increasing temperature, we observed a modest depolarization (3-6 mV) in the period preceding the failure. Prior to the conduction block, action potential amplitude decreased and half-width increased. Both of these failure-associated effects were attenuated following HS. Extracellular potassium concentration ([K+]o) increased sharply at failure and the failure event could be mimicked by the application of high [K+]o. Surges in [K+]o were muted following HS, suggesting that HS may act to stabilize ion distribution. Indeed, experimentally increased [K+]o lowered failure temperature significantly more in control animals than in HS animals and experimentally maintained [K+]o was found to be protective. We suggest that the more attenuated effects of failure on the membrane properties of the DCMD axon in HS animals is consistent with a decrease in the disruptive nature of the [K+]o-dependent failure event following HS and thus represents an adaptive mechanism to cope with thermal stress.
Collapse
Affiliation(s)
- Tomas G A Money
- Queen's University, Department of Biology, Kingston, Ontario, Canada K7L 3N6
| | | | | | | |
Collapse
|
6
|
Mileva-Seitz V, Xiao C, Seroude L, Robertson RM. Tissue-specific targeting of Hsp26 has no effect on heat resistance of neural function in larval Drosophila. Cell Stress Chaperones 2008; 13:85-95. [PMID: 18347945 PMCID: PMC2666220 DOI: 10.1007/s12192-008-0016-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2007] [Revised: 09/10/2007] [Accepted: 09/11/2007] [Indexed: 11/29/2022] Open
Abstract
Hsp26 belongs to the small heat-shock protein family and is normally expressed in all cells during heat stress. We aimed to determine if overexpression of this protein protects behavior and neural function in Drosophila melanogaster during heat stress, as has previously been shown for Hsp70. We used the UAS-GAL4 expression system to drive expression of Hsp26 in the whole animal (ubiquitously), in the motoneurons, and in the muscles of wandering third-instar larvae. There were slight increases in time to crawling failure and normalized excitatory junction potential (EJP) area for some of the transgenic lines, but these were not consistent. In addition, Hsp26 had no effect on the temperature at failure of EJPs, normalized EJP peak amplitude, and normalized EJP half-width. Overexpression larvae had a similar number of motoneuronal boutons and length of nerve terminals as controls, indicating that the occasional protective effects on locomotion were not due to changes at the synapse. We conclude that overexpression had a small thermoprotective effect on locomotion and no effect on neural function. As it has been shown that Hsp26 requires action of other Hsps to reactivate the denatured proteins to which it binds, we propose that at least in larvae, the function of Hsp26 was masked in the relative absence of other Hsps.
Collapse
Affiliation(s)
- Viara Mileva-Seitz
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6 Canada
- Institute of Medical Science, University of Toronto, 7213 Medical Sciences Building, 1 King’s College Circle, Toronto, ON M5S 1A8 Canada
| | - Chengfeng Xiao
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6 Canada
| | - Laurent Seroude
- Department of Biology, Queen’s University, Kingston, ON K7L 3N6 Canada
| | | |
Collapse
|
7
|
Klose MK, Atwood HL, Robertson RM. Hyperthermic preconditioning of presynaptic calcium regulation in Drosophila. J Neurophysiol 2008; 99:2420-30. [PMID: 18272873 DOI: 10.1152/jn.01251.2007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We examined the thermosensitivity of calcium regulation in Drosophila larval neuromuscular junctions, testing effects of prior heat shock and Hsp70 expression. Motor neurons were loaded with either the ratiometric indicator Fura-dextran or the nonratiometric indicator Oregon Green bis-(o-aminophenoxy)-N,N,N',N'-tetraacetic acid to monitor parameters of calcium regulation as temperature increased. Nerve terminals treated to a prior heat shock, and those of transgenic flies expressing higher than normal levels of Hsp70, were better able to maintain near-normal resting calcium concentrations, calcium influx, and calcium clearance at higher temperatures. Synaptic transmission was also protected by prior heat shock and by higher than normal Hsp70 expression. Thus the thermal limit of synaptic transmission may be directly linked to the stability of calcium regulation.
Collapse
Affiliation(s)
- M K Klose
- Department of Physiology, University of Toronto, 1 King's College Circle, Ontario, Canada.
| | | | | |
Collapse
|
8
|
Garlick KM, Robertson RM. Cytoskeletal stability and heat shock-mediated thermoprotection of central pattern generation in Locusta migratoria. Comp Biochem Physiol A Mol Integr Physiol 2007; 147:344-8. [PMID: 17368062 DOI: 10.1016/j.cbpa.2006.10.044] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2006] [Revised: 10/30/2006] [Accepted: 10/31/2006] [Indexed: 10/23/2022]
Abstract
Prior exposure to extreme temperatures can induce thermoprotection in migratory locusts, which is important for survival in their natural environment. An important motor activity that needs to be protected is ventilation. The mechanism underlying heat shock is not fully understood, and our goal was to test the idea that cytoskeletal stability is critical for such thermoprotection. Cytoskeletal stabilizers (concanavalin A) and destabilizers (colchicine) were bath-applied in semi-intact locust preparations in both control (C) and pre-treated heat-shocked (3 h, 45 degrees C) animals. We measured parameters of the ventilatory motor pattern during maintained high temperature (43 degrees C) and recorded the times taken for motor pattern generation to fail and then recover on returning to room temperature. We found that concanavalin A mimicked the effects of a prior heat stress in control animals by increasing time to failure and decreasing time to recovery of motor pattern generation. However, colchicine destroyed protection in heat-shocked animals by decreasing time to failure and increasing time to recovery. Our findings confirm that the cytoskeleton has a mechanistic role in preserving neural function at high temperatures, possibly through stabilizing ion channels and other integral membrane proteins (e.g. Na(+)/K(+) ATPase) and their interactions with heat shock proteins.
Collapse
|
9
|
Buccellato MA, Carsillo T, Traylor Z, Oglesbee M. Heat shock protein expression in brain: a protective role spanning intrinsic thermal resistance and defense against neurotropic viruses. PROGRESS IN BRAIN RESEARCH 2007; 162:395-415. [PMID: 17645929 DOI: 10.1016/s0079-6123(06)62019-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Heat shock proteins (HSPs) play an important role in the maintenance of cellular homeostasis, particularly in response to stressful conditions that adversely affect normal cellular structure and function, such as hyperthermia. A remarkable intrinsic resistance of brain to hyperthermia reflects protection mediated by constitutive and induced expression of HSPs in both neurons and glia. Induced expression underlies the phenomenon of hyperthermic pre-reconditioning, where transient, low-intensity heating induces HSPs that protect brain from subsequent insult, reflecting the prolonged half-life of HSPs. The expression and activity of HSPs that is characteristic of nervous tissue plays a role not just in the maintenance and defense of cellular viability, but also in the preservation of neuron-specific luxury functions, particularly those that support synaptic activity. In response to hyperthermia, HSPs mediate preservation or rapid recovery of synaptic function up to the point where damage in other organ systems becomes evident and life threatening. Given the ability of HSPs to enhance gene expression by neurotropic viruses, the constitutive and inducible HSP expression profiles would seem to place nervous tissues at risk. However, we present evidence that the virus-HSP relationship can promote viral clearance in animals capable of mounting effective virus-specific cell-mediated immune responses, potentially reflecting HSP-dependent increases in viral antigenic burden, immune adjuvant effects and cross-presentation of viral antigen. Thus, the protective functions of HSPs span the well-characterized intracellular roles as chaperones to those that may directly or indirectly promote immune function.
Collapse
Affiliation(s)
- Matthew A Buccellato
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Rd., Columbus, OH 43210, USA
| | | | | | | |
Collapse
|
10
|
Adamo S, Parsons N. The emergency life-history stage and immunity in the cricket, Gryllus texensis. Anim Behav 2006. [DOI: 10.1016/j.anbehav.2006.01.011] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
11
|
Chown SL, Terblanche JS. Physiological Diversity in Insects: Ecological and Evolutionary Contexts. ADVANCES IN INSECT PHYSIOLOGY 2006; 33:50-152. [PMID: 19212462 PMCID: PMC2638997 DOI: 10.1016/s0065-2806(06)33002-0] [Citation(s) in RCA: 313] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Affiliation(s)
- Steven L Chown
- Centre for Invasion Biology, Department of Botany and Zoology, Stellenbosch University, South Africa
| | | |
Collapse
|
12
|
Klose MK, Chu D, Xiao C, Seroude L, Robertson RM. Heat shock-mediated thermoprotection of larval locomotion compromised by ubiquitous overexpression of Hsp70 in Drosophila melanogaster. J Neurophysiol 2005; 94:3563-72. [PMID: 16093328 DOI: 10.1152/jn.00723.2005] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Maintaining the competence of locomotor circuitry under stressful conditions can benefit organisms by enabling locomotion to more tolerable microhabitats. We show that prior heat shock protects locomotion and the locomotor central pattern generator of larval Drosophila against subsequent hyperthermic stress. We combined molecular genetic, electrophysiological, and behavioral techniques to investigate heat shock-mediated thermoprotection. Prior heat shock increased the distance traveled by larvae during hyperthermia before failure. The frequency of the rhythm of peristaltic locomotor contractions and the velocity of locomotion were both less thermosensitive after heat shock and were less susceptible to failure at high temperatures. Rhythmic coordinated motor patterns, recorded intracellularly as excitatory junction potentials in body wall muscles of dissected preparations, were centrally generated because patterns could still be generated in the absence of sensory feedback (sensory function disrupted with shibire). Prior heat shock protected central circuit operation during hyperthermic stress by increasing the temperature at which it failed. Overexpression of Hsp70 after a heat shock using transgenic flies (traII) did not enhance thermoprotection, as expected, but had deleterious effects on parameters of behavior.
Collapse
Affiliation(s)
- Markus K Klose
- Department of Biology, Queen's University, 3118 Biosciences Complex, Kingston, ON, K7L 3N6, Canada
| | | | | | | | | |
Collapse
|
13
|
Money TGA, Anstey ML, Robertson RM. Heat Stress–Mediated Plasticity in a Locust Looming-Sensitive Visual Interneuron. J Neurophysiol 2005; 93:1908-19. [PMID: 15563551 DOI: 10.1152/jn.00908.2004] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Neural circuits are strongly affected by temperature and failure ensues at extremes. However, detrimental effects of high temperature on neural pathways can be mitigated by prior exposure to high, but sublethal temperatures (heat shock). Using the migratory locust, Locusta migratoria, we investigated the effects of heat shock on the thermosensitivity of a visual interneuron [the descending contralateral movement detector (DCMD)]. Activity in the DCMD was elicited using a looming stimulus and the response was recorded from the axon using intracellular and extracellular methods. The thoracic region was perfused with temperature-controlled saline and measurements were taken at 5° intervals starting at 25°C. Activity in DCMD was decreased in control animals with increased temperature, whereas heat-shocked animals had a potentiated response such that the peak firing frequency was increased. Significant differences were also found in the thermosensitivity of the action potential properties between control and heat-shocked animals. Heat shock also had a potentiating effect on the amplitude of the afterdepolarization. The concurrent increase in peak firing frequency and maintenance of action potential properties after heat shock could enhance the reliability with which DCMD initiates visually guided behaviors at high temperature.
Collapse
Affiliation(s)
- Tomas G A Money
- Department of Biology, Queen's University, Biosciences Complex, Kingston, Ontario, Canada K7L 3N6.
| | | | | |
Collapse
|
14
|
|