1
|
Fairless R, Williams SK, Diem R. Calcium-Binding Proteins as Determinants of Central Nervous System Neuronal Vulnerability to Disease. Int J Mol Sci 2019; 20:ijms20092146. [PMID: 31052285 PMCID: PMC6539299 DOI: 10.3390/ijms20092146] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2019] [Revised: 04/26/2019] [Accepted: 04/27/2019] [Indexed: 12/14/2022] Open
Abstract
Neuronal subpopulations display differential vulnerabilities to disease, but the factors that determine their susceptibility are poorly understood. Toxic increases in intracellular calcium are a key factor in several neurodegenerative processes, with calcium-binding proteins providing an important first line of defense through their ability to buffer incoming calcium, allowing the neuron to quickly achieve homeostasis. Since neurons expressing different calcium-binding proteins have been reported to be differentially susceptible to degeneration, it can be hypothesized that rather than just serving as markers of different neuronal subpopulations, they might actually be a key determinant of survival. In this review, we will summarize some of the evidence that expression of the EF-hand calcium-binding proteins, calbindin, calretinin and parvalbumin, may influence the susceptibility of distinct neuronal subpopulations to disease processes.
Collapse
Affiliation(s)
- Richard Fairless
- Department of Neurology, University Clinic Heidelberg, 69120 Heidelberg, Germany.
- Clinical Cooperation Unit (CCU) Neurooncology, German Cancer Consortium (DKTK), German Cancer Research Center (DFKZ), 69120 Heidelberg, Germany.
| | - Sarah K Williams
- Department of Neurology, University Clinic Heidelberg, 69120 Heidelberg, Germany.
- Clinical Cooperation Unit (CCU) Neurooncology, German Cancer Consortium (DKTK), German Cancer Research Center (DFKZ), 69120 Heidelberg, Germany.
| | - Ricarda Diem
- Department of Neurology, University Clinic Heidelberg, 69120 Heidelberg, Germany.
- Clinical Cooperation Unit (CCU) Neurooncology, German Cancer Consortium (DKTK), German Cancer Research Center (DFKZ), 69120 Heidelberg, Germany.
| |
Collapse
|
2
|
Hao Y, Chow AW, Yip WC, Li CH, Wan TF, Tong BC, Cheung KH, Chan WY, Chen Y, Cheng CH, Ko WH. G protein-coupled estrogen receptor inhibits the P2Y receptor-mediated Ca(2+) signaling pathway in human airway epithelia. Pflugers Arch 2016; 468:1489-503. [PMID: 27271044 PMCID: PMC4951515 DOI: 10.1007/s00424-016-1840-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2016] [Revised: 05/11/2016] [Accepted: 05/22/2016] [Indexed: 12/18/2022]
Abstract
P2Y receptor activation causes the release of inflammatory cytokines in the bronchial epithelium, whereas G protein-coupled estrogen receptor (GPER), a novel estrogen (E2) receptor, may play an anti-inflammatory role in this process. We investigated the cellular mechanisms underlying the inhibitory effect of GPER activation on the P2Y receptor-mediated Ca2+ signaling pathway and cytokine production in airway epithelia. Expression of GPER in primary human bronchial epithelial (HBE) or 16HBE14o- cells was confirmed on both the mRNA and protein levels. Stimulation of HBE or 16HBE14o- cells with E2 or G1, a specific agonist of GPER, attenuated the nucleotide-evoked increases in [Ca2+]i, whereas this effect was reversed by G15, a GPER-specific antagonist. G1 inhibited the secretion of two proinflammatory cytokines, interleukin (IL)-6 and IL-8, in cells stimulated by adenosine 5′-(γ-thio)triphosphate (ATPγS). G1 stimulated a real-time increase in cAMP levels in 16HBE14o- cells, which could be inhibited by adenylyl cyclase inhibitors. The inhibitory effects of E2 or G1 on P2Y receptor-induced increases in Ca2+ were reversed by treating the cells with a protein kinase A (PKA) inhibitor. These results demonstrated that the inhibitory effects of G1 or E2 on P2Y receptor-mediated Ca2+ mobilization and cytokine secretion were due to GPER-mediated activation of a cAMP-dependent PKA pathway. This study has reported, for the first time, the expression and function of GPER as an anti-inflammatory component in human bronchial epithelia, which may mediate through its opposing effects on the pro‐inflammatory pathway activated by the P2Y receptors in inflamed airway epithelia.
Collapse
Affiliation(s)
- Yuan Hao
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Alison W Chow
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Wallace C Yip
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Chi H Li
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Tai F Wan
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Benjamin C Tong
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - King H Cheung
- School of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong
| | - Wood Y Chan
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Yangchao Chen
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong
| | - Christopher H Cheng
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong.
| | - Wing H Ko
- School of Biomedical Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong.
| |
Collapse
|
3
|
Schwaller B. Calretinin: from a "simple" Ca(2+) buffer to a multifunctional protein implicated in many biological processes. Front Neuroanat 2014; 8:3. [PMID: 24550787 PMCID: PMC3913827 DOI: 10.3389/fnana.2014.00003] [Citation(s) in RCA: 94] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 01/19/2014] [Indexed: 12/30/2022] Open
Abstract
The hexa-EF-hand Ca(2+)-binding protein calretinin (CR) is predominantly expressed in specific neurons of the central and peripheral nervous system. However, CR expression is also observed in non-neuronal cells, e.g., during embryonic development and in mesothelioma cells. Of the 6 EF-hand domains, 5 are functional; the first 4 domains form 2 pairs showing high cooperativity within a pair that results in non-linear modulation of intracellular Ca(2+) signals by CR. EF-hand domain 5 has a low affinity and represents the identified interaction site with CR-binding partners present in mouse cerebellar granule cells. CR binding to other targets including the pore-forming α1 subunit of the Ca(2+) channel Ca V 2.1, as well as to huntingtin indicates additional Ca(2+) sensor functions besides the well-known Ca(2+)-buffering functions. The absence of CR in cerebellar granule cells of CR(-/-) mice results in increased excitability and altered firing of Purkinje cells and promotes cerebellar 160-Hz oscillations impairing motor coordination. The putative role of CR in neuroprotection is still highly discussed. Altogether, CR emerges as a multi-functional protein also associated with development, i.e., cell proliferation, differentiation, and cell death.
Collapse
Affiliation(s)
- Beat Schwaller
- Anatomy, Department of Medicine, University of FribourgFribourg, Switzerland
| |
Collapse
|
4
|
Kalwat MA, Wiseman DA, Luo W, Wang Z, Thurmond DC. Gelsolin associates with the N terminus of syntaxin 4 to regulate insulin granule exocytosis. Mol Endocrinol 2011; 26:128-41. [PMID: 22108804 DOI: 10.1210/me.2011-1112] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The plasma membrane soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE) protein syntaxin (Syn)4 is required for biphasic insulin secretion, although how it regulates each phase remains unclear. In a screen to identify new Syn4-interacting factors, the calcium-activated F-actin-severing protein gelsolin was revealed. Gelsolin has been previously implicated as a positive effector of insulin secretion, although a molecular mechanism to underlie this function is lacking. Toward this, our in vitro binding studies showed the Syn4-gelsolin interaction to be direct and mediated by the N-terminal Ha domain (amino acid residues 39-70) of Syn4. Syn4-gelsolin complexes formed under basal conditions and dissociated upon acute glucose or KCl stimulation; nifedipine blocked dissociation. The dissociating action of secretagogues could be mimicked by expression of the N-terminal Ha domain of Syn4 fused to green fluorescent protein (GFP) (GFP-39-70). Furthermore, GFP-39-70 expression in isolated mouse islet and clonal MIN6 β-cells initiated insulin release in the absence of appropriate stimuli. Consistent with this, the inhibitory GFP-39-70 peptide also initiated Syn4 activation in the absence of stimuli. Moreover, although MIN6 β-cells expressing the GFP-39-70 peptide maintained normal calcium influx in response to KCl, KCl-stimulated insulin secretion and the triggering pathway of insulin secretion were significantly impaired. Taken together, these data support a mechanistic model for gelsolin's role in insulin exocytosis: gelsolin clamps unsolicited soluble N-ethylmaleimide-sensitive factor attachment receptor (SNARE)-regulated exocytosis through direct association with Syn4 in the absence of appropriate stimuli, which is relieved upon stimulus-induced calcium influx to activate gelsolin and induce its dissociation from Syn4 to facilitate insulin exocytosis.
Collapse
Affiliation(s)
- Michael A Kalwat
- Departments of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA
| | | | | | | | | |
Collapse
|
5
|
Clarkson C, Juíz JM, Merchán MA. Long-term regulation in calretinin staining in the rat inferior colliculus after unilateral auditory cortical ablation. J Comp Neurol 2011; 518:4261-76. [PMID: 20878787 DOI: 10.1002/cne.22453] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
In this study we analyzed the effects in the inferior colliculus of a unilateral ablation of the auditory cortex in rats. Variations in both calretinin immunoreactivity and protein levels determined by Western blot suggest that such lesions induce changes in the regulation of this calcium-binding protein. Stereological counts of calretinin-immunoreactive neurons in the inferior colliculus 15, 90, and 180 days after the lesion showed a progressive increase in the number of immunoreactive neurons, with a parallel increase in the intensity of staining. Two hundred forty days after the cortical lesion, both the number of immunoreactive neurons and the staining intensity had returned to control values. The effects of the cortical lesion on calretinin regulation are more intense in those inferior colliculus subdivisions more densely innervated by the corticocollicular projection. This finding, along with the time course of calretinin regulation suggests that degeneration of the descending projection is linked to calretinin regulation in the inferior colliculus. We hypothesize, based on the role of calretinin, that the observed increase in immunoreactivity levels seen in the inferior colliculus after lesioning of the auditory cortex may be related to altered excitability in deafferented neurons. Our finding, may reflect adaptive mechanisms to changes in calcium influx and excitability in inferior colliculus neurons induced by lesions of the descending projection from the cortex to the inferior colliculus.
Collapse
Affiliation(s)
- Cheryl Clarkson
- Instituto de Neurociencias de Castilla y León, Salamanca, Spain
| | | | | |
Collapse
|
6
|
Billing-Marczak K, Ziemińska E, Leśniak W, Łazarewicz JW, Kuźnicki J. Calretinin gene promoter activity is differently regulated in neurons and cancer cells. Role of AP2-like cis element and zinc ions. ACTA ACUST UNITED AC 2004; 1678:14-21. [PMID: 15093134 DOI: 10.1016/j.bbaexp.2004.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2003] [Revised: 01/14/2004] [Accepted: 01/22/2004] [Indexed: 11/21/2022]
Abstract
Calretinin (CR) is an EF-hand calcium binding protein expressed in a tissue-specific manner. CR gene is active in some neurons, such as cerebellar granule neurons and in some tumor cells such as colon adenocarcinoma or epithelial mesothelioma. Our aim was to understand the mechanism(s) involved in tissue-specific regulation of CR gene transcription. Our recent paper showed that an "AP2-like" sequence located between -90/-80 bp of the CR gene promoter is important for specific expression of this gene in neurons differentiating from DEV multipotent cells [Biochim. Biophys. Acta (1577) 2000 412]. We now show by electrophoretic mobility shift assay (EMSA) that in cerebellar granule neurons, there is a nuclear protein that interacts with the "AP2-like" sequence. This interaction results in an increased CR gene promoter activity. In contrast, the "AP2-like" sequence does not play such a role in regulation of the CR gene transcription in adenocarcinoma and mesothelioma cancer cells. In these cells mutation in the "AP2-like" element did not affect transcriptional activity of the CR gene promoter and no protein binding to this element was observed by EMSA. These data clearly show that expression of CR gene in neurons and cancer cells is regulated by different mechanisms. On the other hand, in both cell types, the activity of CR gene promoter can be stimulated by zinc ions.
Collapse
Affiliation(s)
- Katarzyna Billing-Marczak
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warsaw, Poland
| | | | | | | | | |
Collapse
|
7
|
Berkova Z, Morris AP, Estes MK. Cytoplasmic calcium measurement in rotavirus enterotoxin-enhanced green fluorescent protein (NSP4-EGFP) expressing cells loaded with Fura-2. Cell Calcium 2003; 34:55-68. [PMID: 12767893 DOI: 10.1016/s0143-4160(03)00022-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The green fluorescent protein (GFP) and its analogs are standard markers of protein expression and intracellular localization of proteins. The fluorescent properties of GFP complicate accurate measurement of intracellular calcium using calcium sensitive fluorophores, which show a great degree of spectral overlap with GFP, or their K(d) values are too high for accurate measurement of subtle changes in cytoplasmic calcium concentrations. Here we describe a simple modification of the standard microscope-based Fura-2 calcium-imaging technique which permits the quantitative measurement of intracellular calcium levels in cells expressing enhanced green fluorescent protein (EGFP) fusion proteins. Longpass emission filtering of the Fura-2 signal in cells expressing an EGFP fusion protein is sufficient to eliminate the EGFP-Fura-2 emission spectra overlap and allows quantitative calibration of intracellular calcium. To validate this technique, we investigated the ability of rotavirus enterotoxin NSP4-EGFP to elevate intracellular calcium levels in mammalian HEK 293 cells. We show here that inducible intracellular expression of NSP4-EGFP fusion protein elevates basal intracellular calcium more than two-fold by a phospholipase C (PLC) independent mechanism.
Collapse
Affiliation(s)
- Z Berkova
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA
| | | | | |
Collapse
|
8
|
Melvin NR, Dyck RH. Developmental distribution of calretinin in mouse barrel cortex. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2003; 143:111-4. [PMID: 12763586 DOI: 10.1016/s0165-3806(03)00102-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We describe the postnatal development of calretinin expression in the mouse barrel cortex by immunohistochemistry. A densely staining neuropil and numerous cell bodies appeared throughout layer V, but only within barrel septa of layer IV, at postnatal day 4. This staining pattern became most robust at postnatal day 8. Thereafter, calretinin expression became reduced until the third postnatal week when it attained its mature levels, and the barrel-specific staining was no longer apparent.
Collapse
Affiliation(s)
- Neal R Melvin
- Neuroscience Research Group, Department of Neuroscience, University of Calgary, Calgary, Alberta, Canada T2N 4N1
| | | |
Collapse
|
9
|
Schwaller B, Meyer M, Schiffmann S. 'New' functions for 'old' proteins: the role of the calcium-binding proteins calbindin D-28k, calretinin and parvalbumin, in cerebellar physiology. Studies with knockout mice. CEREBELLUM (LONDON, ENGLAND) 2002; 1:241-58. [PMID: 12879963 DOI: 10.1080/147342202320883551] [Citation(s) in RCA: 295] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Calretinin (CR), calbindin D-28k (CB) and parvalbumin (PV) belong to the large family of EF-hand calcium-binding proteins, which comprises more than 200 members in man. Structurally these proteins are characterized by the presence of a variable number of evolutionary well-conserved helix-loop-helix motives, which bind Ca2+ ions with high affinity. Functionally, they fall into two groups: by interaction with target proteins, calcium sensors translate calcium concentrations into signaling cascades, whereas calcium buffers are thought to modify the spatiotemporal aspects of calcium transients. Although CR, CB and PV are currently being considered calcium buffers, this may change as we learn more about their biology. Remarkable differences in their biophysical properties have led to the distinction of fast and slow buffers and suggested functional specificity of individual calcium buffers. Evaluation of the physiological roles of CR, CB and PV has been facilitated by the recent generation of mouse strains deficient in these proteins. Here, we review the biology of these calcium-binding proteins with distinct reference to the cerebellum, since they are particularly enriched in specific cerebellar neurons. CR is principally expressed in granule cells and their parallel fibres, while PV and CB are present throughout the axon, soma, dendrites and spines of Purkinje cells. PV is additionally found in a subpopulation of inhibitory interneurons, the stellate and basket cells. Studies on deficient mice together with in vitro work and their unique cell type-specific distribution in the cerebellum suggest that these calcium-binding proteins have evolved as functionally distinct, physiologically relevant modulators of intracellular calcium transients. Analysis of different brain regions suggests that these proteins are involved in regulating calcium pools critical for synaptic plasticity. Surprisingly, a major role of any of these three calcium-binding proteins as an endogenous neuroprotectant is not generally supported.
Collapse
Affiliation(s)
- Beat Schwaller
- Institute of Histology and General Embryology, University of Fribourg, Fribourg, Switzerland.
| | | | | |
Collapse
|
10
|
Araki CM, Hamassaki-Britto DE. Calretinin co-localizes with the NMDA receptor subunit NR1 in cholinergic amacrine cells of the rat retina. Brain Res 2000; 869:220-4. [PMID: 10865078 DOI: 10.1016/s0006-8993(00)02364-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Immunohistochemistry was used to verify whether choline-acetiltransferase colocalizes with calcium-binding proteins and NMDA receptor subunit NR1 in the rat retina. Whereas calbindin and parvalbumin were not observed in cholinergic amacrine cells, calretinin and NR1 were very frequently colocalized with ChAT. Calretinin/NR1-positive cells were also shown, suggesting that calretinin in cholinergic cells of the rat may be related to the buffering of excess intracellular calcium generated by activation of NMDA receptors.
Collapse
Affiliation(s)
- C M Araki
- Department of Histology and Embryology, Institute of Biomedical Sciences, University of São Paulo, Av. Prof. Lineu Prestes 1524, SP 05508-900, São Paulo, Brazil
| | | |
Collapse
|
11
|
Bubser M, Scruggs JL, Young CD, Deutch AY. The distribution and origin of the calretinin-containing innervation of the nucleus accumbens of the rat. Eur J Neurosci 2000; 12:1591-8. [PMID: 10792437 DOI: 10.1046/j.1460-9568.2000.00052.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The nucleus accumbens of the rat consists of several subregions that can be distinguished on the basis of histochemical markers. For example, the calcium-binding protein calbindin D28k is a useful marker of the core compartment of the nucleus accumbens. Calretinin, another calcium-binding protein, is found in a dense fibre plexus in the accumbal shell and septal pole regions. The source of the accumbal calretinin innervation is not known. We examined the distribution of calretinin in the nucleus accumbens and used tract-tracing and lesion methods to determine the source of this calretinin innervation. Intense calretinin immunoreactivity was present in the medial shell, but the density of calretinin axons diminished sharply in the ventrolateral shell. Regions of dense calretinin immunostaining and those areas with calbindin-like immunoreactive cell bodies were generally segregated in the nucleus accumbens, although some overlap in the transition region between the core and shell was seen. Small clusters of calretinin-immunoreactive fibres were seen in the core, where they were restricted to calbindin-negative patches. Injections of the anterograde tracer biotinylated dextran amine into the paraventricular thalamic nucleus labelled fibres in calretinin-rich regions of the accumbens. Conversely, injections of Fluoro-gold into the accumbal shell retrogradely labelled numerous cells in the paraventricular thalamic nucleus that were calretinin-immunoreactive. Electrolytic lesions of the paraventricular thalamic nucleus reduced calretinin levels in the shell by approximately 80%. These data indicate that the calretinin innervation of the nucleus accumbens is derived primarily from the thalamic paraventricular nucleus, and marks accumbal territories that are largely complementary to those defined by calbindin.
Collapse
Affiliation(s)
- M Bubser
- Departments of Psychiatry and Pharmacology and Center for Molecular Neuroscience, Vanderbilt University School of Medicine, Nashville, TN 37212, USA.
| | | | | | | |
Collapse
|
12
|
Palczewska M, Groves P, Kuznicki J. Use of Pichia pastoris for the expression, purification, and characterization of rat calretinin "EF-hand" domains. Protein Expr Purif 1999; 17:465-76. [PMID: 10600467 DOI: 10.1006/prep.1999.1154] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Calretinin (CR) is a calcium-binding, neuronal protein of undefined function. Related proteins either buffer intracellular calcium concentrations or are involved in calcium-signaling pathways. We transformed three CR gene fragment sequences, corresponding to its three complementary domains (I-II, III-IV, and V-VI), into Pichia pastoris. High yields of extracellular expression, of more than 200 mg/liter, were achieved. Simple purification protocols provide high yields of homogenous proteins: dialysis and DEAE-cellulose chromatography for domains I-II and III-IV or ammonium sulfate precipitation and octyl-Sepharose chromatography for domain V-VI. To our knowledge, this is the first report of the expression of an EF-hand protein using P. pastoris. Direct comparison of the purified yields of domain I-II indicates a approximately 20-fold improvement over Escherichia coli. N-terminal amino acid sequencing confirmed our gene products and two anti-calretinin antibodies recognized the appropriate domains. All three CR domains bind (45)Ca and the domain containing EF-hands V and VI seems to have a lower calcium capacity than the other domains. Circular dichroism indicates a high helix content for each of the domains. Calcium-induced structural changes in the first two domains, followed by tryptophan fluorescence, correspond with previous studies, while tyrosine emission fluorescence indicates calcium-induced structural changes also occur in domain V-VI. The methods and expression levels achieved are suitable for future NMR labeling of the proteins, with (15)N and (13)C, and structure-function studies that will help to further understand CR function.
Collapse
Affiliation(s)
- M Palczewska
- Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, 3 Pasteur Street, Warsaw, 02-093, Poland
| | | | | |
Collapse
|
13
|
Nemoto C, Hida T, Arai R. Calretinin and calbindin-D28k in dopaminergic neurons of the rat midbrain: a triple-labeling immunohistochemical study. Brain Res 1999; 846:129-36. [PMID: 10536220 DOI: 10.1016/s0006-8993(99)01950-2] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We used triple-labeling immunohistochemistry in rat midbrain sections to identify dopaminergic neurons that contain either one or both of the calcium-binding proteins, calretinin (CR) and calbindin-D28k (CB). Midbrain dopaminergic neurons were immunohistochemically labeled for tyrosine hydroxylase (TH), CR, and CB. In the substantia nigra pars compacta (SNC), TH+/CR+/CB+ cells were clustered in two regions: the dorsal tier of the rostral SNC and the medial part of the intermediate SNC. The ventral tier of the rostral SNC mainly comprised both TH+/CR+/CB- and TH+/CR-/CB- cells. The lateral part of the intermediate SNC and the caudal SNC primarily consisted of TH+/CR-/CB- cells. Throughout the extent of the SNC, approximately half of the TH+ neurons were stained for neither CR nor CB, while the remaining TH+ populations were labeled for CR and/or CB. Throughout the ventral tegmental area, TH+/CR+/CB+ cells, TH+/CR+/CB- cells, TH+/CR-/CB+ cells, and TH+/CR-/CB- cells were found generally scattered, though the TH+/CR-/CB- cells were dominant in number. In the substantia nigra pars lateralis, interfascicular nucleus, and caudal linear nucleus, more than half of the TH+ cells were stained for both CR and CB. In the retrorubral field, two-thirds of the TH+ neurons contained neither protein. The present findings suggest that the SNC can be divided into subcompartments based on the distribution of dopaminergic neurons that contain calcium-binding proteins. Furthermore, because CR and CB likely contribute to calcium homeostasis by buffering intracellular calcium concentrations, midbrain dopaminergic neurons containing one or both of these calcium-binding proteins may have a higher calcium-buffering capacity than those lacking the two proteins.
Collapse
Affiliation(s)
- C Nemoto
- Department of Anatomy, Fujita Health University School of Medicine, Toyoake, Aichi 470-1192, Japan
| | | | | |
Collapse
|