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PubMed1997

Quantitative analysis of GAD65 and GAD67 immunoreactivities in somata of GABAergic neurons in the mouse hippocampus proper (CA1 and CA3 regions), with special reference to parvalbumin-containing neurons.

Intensities of the immunoreactivities against two GAD isoforms, GAD65 and GAD67, were examined quantitatively in somata of GABAergic neurons in the mouse hippocampus proper. All labeled somata contained both isoforms but showed diverse immunoreactivities against them. The somata showing weak immunoreactivity for GAD65 but moderate to intense immunoreactivity for GAD67 were frequently located in the stratum pyramidale of the CA1 and CA3 regions and were mainly composed of parvalbumin-containing neurons, a particular subpopulation of hippocampal GABAergic neurons. These data revealed additional distinctive properties of parvalbumin-containing neurons and suggest their specialized roles in the hippocampal GABAergic system.

Animals↗
PubMed1997

Coexpression of calretinin and parvalbumin in Ruffini-like endings in the rat incisor periodontal ligament.

The coexpression of calretinin- (CR) and parvalbumin-immunoreactivities (irs) was examined in oro-facial tissues of the rat. Nerve fibers coexpressing these calcium-binding proteins (CaBPs) were observed in the lingual periodontal ligament of incisors but not other tissues. In the part of periodontal ligament adjacent to the alveolar bone, such nerve fibers left nerve bundles and formed bush-like endings, i.e., they ramified repeatedly and terminated with one to four twigs. An immunoelectron microscopic method indicated that these endings were identical to Ruffini-like endings, 4% of trigeminal neurons retrogradely labeled from the inferior alveolar nerve coexpressed CR- and parvalbumin-irs. The present observations suggest that the coexpression of these CaBPs may be a specific marker for low-threshold mechanoreceptors in the trigeminal ganglion.

Animals↗
PubMed1997

Ultrastructural study of nitric oxide synthase-containing striatal neurons and their relationship with parvalbumin-containing neurons in rats.

Single- and double-label electron microscopic immunocytochemistry was used to examine the ultrastructure of striatal neurons containing nitric oxide synthase (NOS+) and evaluate the synaptic relationship of NOS+ striatal neurons with those containing parvalbumin (PV+). In both the single-label and double-label studies, NOS+ perikarya were observed to possess polylobulated nuclei. In the single-label studies, NOS+ terminals were seen forming synaptic contacts with dendritic shafts and dendritic spines that did not contain NOS, but not with NOS+ perikarya or dendrites. In the double-label studies (using diaminobenzidine and silver intensified immunogold as markers), nitric oxide synthase and parvalbumin immunoreactions were found in two different populations of medium-sized aspiny striatal neurons. The PV+ axon terminals were seen forming symmetric synapses on the dendritic spines of neurons devoid of PV or NOS labeling, on PV+ dendrites, and on NOS+ soma and dendrites. In contrast, NOS+ terminals were not observed to form synaptic contacts with the dendrites or soma of either PV+ or NOS+ neurons. These findings suggest that NOS+ striatal interneurons form synaptic contact with the spines and presumably the dendrites of striatal projection neurons, but not with the dendrites or soma of PV+ or NOS+ striatal interneurons. NOS+ neurons do, however, receive synaptic input from PV+ neurons.

Animals↗
PubMed1998

Prenatal ethanol exposure reduces parvalbumin-immunoreactive GABAergic neuronal number in the adult rat cingulate cortex.

The effect of prenatal ethanol exposure on the number of parvalbumin-immunoreactive (PA+) GABAergic neurons in the adult rat anterior cingulate cortex was determined. Pregnant Long-Evans rats were maintained on one of three diets throughout gestation: an ethanol-containing liquid diet, a similar, control liquid diet with the isocaloric substitution of sucrose for ethanol, or a lab chow control diet. Offspring were euthanized on postnatal day 60 and brains were prepared for parvalbumin immunocytochemistry. Rats exposed to the ethanol-containing diet contained 45% fewer PA+ neurons in the anterior cingulate cortex compared with sucrose and chow controls. This reduction occurred in the absence of changes in structure volume, and occurred in the absence of changes in PA+ neuronal size.

Animals↗
PubMed2000

Neurodegenerative and morphogenic changes in a mouse model of temporal lobe epilepsy do not depend on the expression of the calcium-binding proteins parvalbumin, calbindin, or calretinin.

The functional role of the calcium-binding proteins parvalbumin, calretinin, and calbindin D-28k for epileptogenesis and long-term seizure-related alterations of the hippocampal formation was assessed in single- and double-knockout mice, using a kainate model of mesial temporal lobe epilepsy. The effects of a unilateral intrahippocampal injection of kainic acid were assessed at one day, 30 days, and four months post-injection, using various markers of GABAergic interneurons (GABA-transporter type 1, GABA(A)-receptor alpha1 subunit, calretinin, calbindin D-28k, somatostatin, and neuropeptide Y). Parvalbumin-deficient, parvalbumin/calbindin-deficient, and parvalbumin/calretinin-deficient mice exhibited no difference in cytoarchitecture of the hippocampal formation and in the number, distribution, or morphology of interneurons compared to wild-type mice. Likewise, mutant mice were not more vulnerable to acute kainate-induced excitotoxicity or to long-term effects of recurrent focal seizures, and exhibited the same pattern of neurochemical alterations (e.g., bilateral induction of neuropeptide Y in granule cells) and morphogenic changes (enlargement and dispersion of dentate gyrus granule cells) as wild-type animals. Quantification of interneurons revealed no significant difference in neuronal vulnerability among the genotypes.These results indicate that the calcium-binding proteins investigated here are not essential for determining the neurochemical phenotype of interneurons. Furthermore, they are not protective against kainate-induced excitotoxicity in this model, and do not appear to modulate the overall level of excitability of the hippocampus. Finally, seizure-induced changes in gene expression in granule cells, which normally express high levels of calcium-binding proteins, apparently were not affected by the gene deletions analysed.

Animals↗
PubMed2000

Distribution of the calcium-binding proteins parvalbumin, calbindin D-28k and calretinin in the retina of two teleosts.

Using monoclonal antibodies against parvalbumin (PV) and calbindin (CB), and a polyclonal antiserum against calretinin (CR), the expression patterns of these proteins in the retina of the tench and rainbow trout were studied at light microscopic level in in toto preparations and radial sections. Parvalbumin was present in subpopulations of small amacrine cells in both species, but these cells were more abundant and had a clear centre-periphery gradient distribution in the tench. Using the McAB 300 monoclonal antibody against CB, glial cells such as Müller cells, astrocytes in the nerve fibre layer, and sparse large cells close to the entrance of the optic nerve were observed in both species. Moreover, this antibody strongly labelled H1 horizontal cells and their thick axon terminals in the tench retina, whereas only a small population of amacrine cells was stained in the trout. Calretinin was expressed in different types of ganglion cells and numerous neurones located in the inner plexiform layer in both species, but was more abundant and more strongly stained in the trout retina, where some bipolar cells were easily distinguishable. A comparison to current results in other vertebrate species is offered.

Animals↗
PubMed1997

Types of neurons, synaptic connections and chemical characteristics of cells immunoreactive for calbindin-D28K, parvalbumin and calretinin in the neocortex.

This article provides a general account of types of neurons, synaptic connections and chemical characteristics (colocalization studies) of cells immunoreactive for the three main calcium-binding proteins found in the neocortex, namely, calbindin-D28K, parvalbumin and calretinin. The main conclusion is two-fold. First, all, or the majority, of calbindin-, parvalbumin- and calretinin-immunoreactive cells are smooth nonpyramidal neurons (interneurons) which participate in a variety of complex cortical circuits that may differ depending on the species, cortical area or layer where they are located. Second, in general, different types of nonpyramidal neurons are stained for each of these calcium-binding proteins and display different chemical characteristics regarding a variety of neurotransmitters (or related compounds), cell surface markers and receptors. However, a certain overlap exits, which also shows regional and species differences.

Adult↗
PubMed2002

Immunological study of muscle parvalbumin isotypes in three African catfish during development.

Eleven parvalbumin isotypes expressed during the development of clariids Heterobranchus longifilis and Clarias gariepinus and claroteid Chrysichthys auratus were purified and electrophoresed on sodium-dodecyl-sulfate polyacrylamide gels. Immunochemical cross-reactions among these proteins were investigated by immunoblotting, using purified antibodies raised against three isotypes chosen at different stages of fish development. Antibodies raised against H. longifilis PA I (larval-juvenile isotype) and against C. gariepinus PA IIIa (juvenile-adult isotype) cross-reacted to a rather similar extent despite a weaker cross-reaction of anti-PA IIIa with larval-juvenile isotypes. On the other hand, antibodies raised against H. longifilis PA IV (an exclusively adult isotype) recognized markedly only H. longifilis PA IV and C. gariepinus PA IIIb. These two adult isotypes most likely belong to the alpha lineage, and all the others to the beta lineage. These results show that parvalbumin isotypes synthesized at different stages of fish growth differ structurally, and that the most marked difference is between larval-juvenile and adult clariid isotypes.

Animals↗
PubMed1989

cDNA sequence and chromosomal localization of the mouse parvalbumin gene, Pva.

In the homozygous condition, the mutation adr (arrested development of righting response) of the mouse causes a myotonia and a drastic reduction of the Ca2+-binding protein parvalbumin (PV) in fast muscles. Using a rat PV probe, a mouse cDNA clone was isolated from a lambda gt11 wild-type fast-muscle library and its nucleotide sequence was determined. The protein coding and the 3' nontranslated regions of the mouse gene show extensive homology with the rat PV gene. The result of Southern blot hybridization is consistent with a single copy gene for parvalbumin. Restriction fragment length polymorphisms (RFLPs) between Mus musculus domesticus (e.g. C57BL/6) and Mus spretus (SPE) were detected with the enzymes Eco RI, Pst I, and Sst I. The restriction fragment patterns of DNA samples from 65 individual offspring of (C57BL/6 x SPE)F1 x C57BL/6 backcrosses were tested with the PV probe and matched, for linkage detection, to pre-existing patterns established with various RFLP probes on the same samples. A co-distribution of PV-RFLPs with Pvt-1 and Mlvi-2, which had been localized on chromosome 15, was detected. Thus, the structural gene for PV, designated Pva, maps to chromosome 15 of the mouse whereas the adr mutation shows no linkage with markers on this chromosome. Gene locus homology between chromosome 15 of the mouse and chromosome 22 of man (which carries the human PV gene) is discussed.

Amino Acid Sequence↗
PubMed1995

Dynamics of parvalbumin studied by fluorescence emission and triplet absorption spectroscopy of tryptophan.

Fluorescence emission and triplet-triplet absorbance spectroscopy of the single tryptophan in cod parvalbumin were used to study the stability and dynamics of the protein as influenced by Ca2+ binding and interaction with a chaotropic agent. The concentrations for half-saturation for Ca binding were 3.6 x 10(-9), 3.3 x 10(-4), 7.1 x 10(-3), and 0.14 M in the presence of 0, 2, 3, and 4 M guanidine hydrochloride, respectively. As predicted for thermodynamic reversibility, the guanidine hydrochloride unfolding reaction depends upon Ca2+, and the delta G are as follows: 22.9, 29.3, 35.2, and 44.2 kJ/mol for no added Ca2+, 1, 2, and 5 mM Ca2+, respectively. The stability toward denaturation imparted by the binding of two Ca2+ is about -60 kJ/mol. For Ca(2+)-bound parvalbumin in the presence of excess Ca2+, the decay of the triplet state tryptophan is approximately exponential, and the lifetime decreases from 6.5 to 3.8 ms as the temperature increases from 10 to 40 degrees C. In contrast, the triplet decay of the calcium-free protein is nonexponential over the time range of microseconds to milliseconds, a result that may indicate that the Ca-free protein is molten-globule-like. At Ca2+ concentrations where the protein is partially saturated with Ca2+, the lifetime of the longest decay component is less than that for the Ca-saturated protein; this finding suggests an exchange of Ca2+ and a conformational change during the triplet lifetime. From these data, a rate constant for the process that includes calcium-related protein conformational change can be surmised to range between 200 and 500 s-1.

Animals↗
PubMed1992

Probing the metal-binding sites of cod parvalbumin using europium(III) ion luminescence and diffusion-enhanced energy transfer.

Excitation spectroscopy of the 7F0----5D0 transition of Eu3+ and diffusion-enhanced energy transfer are used to study metal-binding characteristics of the calcium-binding protein parvalbumin from codfish. Energy is transferred from Eu3+ ions occupying the CD- and EF-binding sites to the freely-diffusing Co(III) coordination complex energy acceptors: [Co(NH3)6]3+, [Co(NH3)5H2O]3+, [CoF(NH3)5]2+, [CoCl(NH3)5]2+, [Co(NO2)3(NH3)3], and [Co(ox)3]3-. In the absence of these inorganic energy acceptors, the excited-state lifetimes of Eu3+ bound to the CD and EF sites are indistinguishable, even in D2O; however, in the presence of the positively charged energy acceptor complexes, the Eu3+ probes in the cod parvalbumin have different excited-state lifetimes due to a greater energy-transfer site from Eu3+ in the CD site than from this ion in the EF site. The observation of distinct lifetimes for Eu3+ in the two sites allows the study of the relative binding site affinities and selectivity, using other members of the lanthanide ion series. Our results indicate that during the course of a titration of the metal-free protein, Eu3+ fills the two sites simultaneously. Eu3+ is competitively displaced by other Ln3+ ions, with the CD site showing a preference for the larger Ln3+ ions while the EF site shows little, if any, competitive selectivity across the Ln3+ ion series.

Animals↗
PubMed1994

Inactivation of individual Ca(2+)-binding sites in the paired EF-hand sites of parvalbumin reveals asymmetrical metal-binding properties.

Previously a rat parvalbumin mutant protein PVF102W was constructed with a reporter Trp at position 102 in the middle of the hydrophobic center [Pauls, T. L., et al. (1993) J. Biol. Chem. 268, 20897-20903]. In the present study three new parvalbumin mutant proteins, derived from PVF102W and containing alterations at positions essential for Ca2+ binding in either one of the two Ca(2+)-binding sites (PV-CD and PV-EF) or in both (PV-CD/-EF), were expressed and purified. With the flow dialysis method it was established that both PV-CD and PV-EF bind 1 Ca2+ with affinity constants KCa of 1.1 x 10(7) and 3.2 x 10(6) M-1, respectively. Mg2+ binding, monitored by equilibrium gel filtration in the absence of Ca2+, showed that both mutants bind 1 Mg2+ with KMg = 8 10(4) for PV-CD and 3 x 10(3) M-1 for PV-EF. Compared to the parameters of the parent mutant PVF102W (two sites with equal affinities of 2.7 x 10(7) and 3 x 10(4) M-1 for Ca2+ and Mg2+, respectively), these data indicate that inactivation of the EF site, much more than of the CD site, impairs divalent cation binding. The binding of Ca2+ and Mg2+ is mutually exclusive, indicative of a Ca2+/Mg2+ mixed site. However, as for PVF102W, the KMg values obtained from the competition equation are approximately 40-fold lower than the affinities measured by direct binding. PV-CD/-EF binds neither Ca2+ nor Mg2+. Trp fluorimetry revealed that in the three mutant PVs the residue Trp-102 is deeply buried in the hydrophobic core.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Fluorescence lifetime and solute quenching studies with the single tryptophan containing protein parvalbumin from codfish.

The fluorescence decay of cod parvalbumin (both its Ca2+-loaded and Ca2+-depleted forms) is found to be a nonexponential process. The decay data can be fitted either by a double-exponential decay law or by a distribution of decay times. To try to distinguish between the double-exponential and distribution fits, we have collected frequency domain and steady-state fluorescence data as a function of temperature and concentration of the quencher acrylamide. We argue that the correct decay law (i.e., double exponential or distribution) must be consistent with all the data collected as a function of temperature and quencher concentrations. We employ a global analysis procedure to simultaneously fit multiple data sets that are linked by an Arrhenius or Stern-Volmer relationship. For the Ca2+-loaded form of parvalbumin, the distribution model provides a consistent and reasonable fit for all of the frequency domain and steady-state data. The double-exponential model requires more fitting parameters, and some of these assume unreasonable values when this model is fitted to all of the data. For the Ca2+-depleted form of the protein, it is not clear whether the double-exponential or distribution model is superior. For our steady-state solute quenching studies we present a novel analysis in terms of a distribution of quenching constants.

Acrylamide↗
PubMed1981

Proton nuclear magnetic resonance determination of the sequential ytterbium replacement of calcium in carp parvalbumin.

The substitution of the paramagnetic lanthanide ion ytterbium for the calcium ions bound to the CD and EF sites of carp parvalbumin results in a series of 1H NMR resonances which are shifted far outside the envelope of the 1H NMR spectrum of the diamagnetic form of the protein. Titration of Ca2+-saturated parvalbumin with ytterbium (YB3+) demonstrate that Yb3+ sequentially replaces the two bound calcium ions of the protein. Analysis of the 1H NMR data yields the relative affinities of the two sites (CD and EF) for ytterbium with respect to calcium. The dissociation constants for ytterbium are then calculated to be KYb3+CD equals (4-7) x 10(-10) M and KYb3+EF equals (2-6) x 10(-10) M from the known dissociation constants for calcium [Haiech, J., Derancourt, J., Pechere, J.-F., & Demaille, J. G. (1979) Biochemistry 18, 2752-2758]. The approximate equality of these constants is verified by Yb3+ titrations of apoparvalbumin.

Animals↗
PubMed1979

Salt-induced conformational changes in skeletal myosin light chains, troponin-C, and parvalbumin.

Evidence for salt-induced changes in myosin light chains [dissociated by treatment with 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB)], troponin-C (TnC), and parvalbumin was obtained from chymotryptic digestion, circular dichroism, fluorescence, and difference absorption studies. High salt (0.6 M NaCl) protects the DTNB light chain from proteolysis, increases its alpha-helical content, and quenches the tryptophan fluorescence. These effects are similar to the changes induced by Ca2+ but smaller in magnitude. TnC is affected by monovalent cations in a similar manner. Changes in the alpha-helical content resemble the effect of Ca2+. The enhancement of tyrosine fluorescence reflects conformational changes in the Ca2+-Mg2+ binding sites. The increase in the fluorescence of dansylaziridine-labeled TnC suggests perturbation of Ca2+-specific sites by salt. Cancellation of this effect by Mg2+ binding to the high-affinity sites is indicative of site-site interactions. In Whiting parvalbumin, salt-induced a perturbation of tryptophan absorption similar in nature to the Ca2+ effect.

Animals↗
PubMed2003

Impact of proline residues on parvalbumin stability.

Despite its higher net charge and reduced opportunities for favorable tertiary interactions, Ca(2+)-free rat beta-parvalbumin is more stable than rat alpha-parvalbumin. Under conditions wherein alpha denatures at 45.8 degrees C, beta denatures at 53.6 degrees. The homologous chicken beta isoform known as CPV3 also exhibits heightened stability-prompting an inquiry into the stabilizing influence of Pro-21 and Pro-26. Individual P21A and P26A mutations lower the T(m) of rat beta by 3.2 degrees, decreasing conformational stability by 0.74 kcal/mol. Simultaneous replacement of Pro-21 and Pro-26 essentially abolishes the excess stability (DeltaT(m) = -7.6 degrees; DeltaDeltaG(conf) = -1.77 kcal/mol). Significantly, the P21A/P26A variant displays Ca(2+) affinity virtually indistinguishable from wild-type beta, implying that structural alterations in the AB domain do not necessarily influence the divalent ion affinity of the CD-EF domain. The consequences of introducing proline at positions 21 and 26 in rat alpha were also examined. Whereas the H26P mutation raises the T(m) by 5.6 degrees (DeltaDeltaG(conf) = 1.25 kcal/mol), A21P lowers the T(m) by 8.5 degrees (DeltaDeltaG(conf) = -1.9 kcal/mol). Replacement of Ala-21 by proline in an alpha AB/beta CD-EF chimera increases the T(m) by 5.8 degrees (DeltaDeltaG(conf) = 0.95 kcal/mol), implying that the destabilization of alpha by Pro-21 results from steric conflict with a residue in the CD-EF domain. Consistent with that hypothesis, the K80S mutation markedly stabilizes alpha A21P, yielding a protein with a T(m) 2.0 degrees higher than wild-type alpha. The observed differences in stability resulting from proline addition/removal are largely consistent with alterations in main-chain and side-chain conformational entropy.

Amino Acid Sequence↗
PubMed2004

Influence of monovalent cation identity on parvalbumin divalent ion-binding properties.

Rat alpha- and beta-parvalbumins have distinct monovalent cation-binding properties [Henzl et al. (2000) Biochemistry 39, 5859-5867]. Beta binds two Na(+) or one K(+), and alpha binds one Na(+) and no K(+). Ca(2+) abolishes these binding events, suggesting that the monovalent ions occupy the EF-hand motifs. This study compares alpha and beta divalent ion affinities in Na(+) and K(+) solutions. Solvent cation identity seriously affects alpha. In Hepes-buffered NaCl, at 5 degrees C, the macroscopic Ca(2+)-binding constants are 2.6 x 10(8) and 6.4 x 10(7) M(-1) and the Mg(2+) constants, 1.8 x 10(4) and 4.3 x 10(3) M(-1). In Hepes-buffered KCl, the Ca(2+) values increase to 2.9 x 10(9) and 6.6 x 10(8) M(-1) and the Mg(2+) values to 2.2 x 10(5) and 3.7 x 10(4) M(-1). Monte Carlo simulation of alpha binding data-employing site-specific constants and explicitly considering Na(+) binding-yields a K(Na) of 630 M(-1) and indicates that divalent ion-binding is positively cooperative. NMR data suggest that the lone Na(+) ion occupies the CD loop. Solvent cation identity has a smaller impact on beta. In Na(+), the Ca(2+) constants for the EF and CD sites are 2.3 x 10(7) and 1.5 x 10(6) M(-1), respectively; the Mg(2+) constants are 9.2 x 10(3) and 1.7 x 10(2) M(-1). In K(+), these values shift to 3.1 x 10(7) and 3.8 x 10(6) M(-1) and the latter to 1.4 x 10(4) and 2.9 x 10(2) M(-1). These data suggest that parvalbumin divalent ion affinity, particularly that of rat alpha, can be significantly attenuated by increased intracellular Na(+) levels.

Animals↗
PubMed2004

Crystal structure of a high-affinity variant of rat alpha-parvalbumin.

In model peptide systems, Ca2+ affinity is maximized in EF-hand motifs containing four carboxylates positioned on the +x and -x and +z and -z axes; introduction of a fifth carboxylate ligand reduces the affinity. However, in rat beta-parvalbumin, replacement of Ser-55 with aspartate heightens divalent ion affinity [Henzl, M. T., et al. (1996) Biochemistry 35, 5856-5869]. The corresponding alpha-parvalbumin variant (S55D/E59D) likewise exhibits elevated affinity [Henzl, M. T., et al. (2003) Anal. Biochem. 319, 216-233]. To determine whether these mutations produce a variation on the archetypal EF-hand coordination scheme, we have obtained high-resolution X-ray crystallographic data for alpha S55D/E59D. As anticipated, the aspartyl carboxylate replaces the serine hydroxyl at the +z coordination position. Interestingly, the Asp-59 carboxylate abandons the role it plays as an outer sphere ligand in wild-type rat beta, rotating away from the Ca2+ and, instead, forming a hydrogen bond with the amide of Glu-62. Superficially, the coordination sphere in the CD site of alpha S55D/E59D resembles that in the EF site. However, the orientation of the Asp-59 side chain is predicted to stabilize the D-helix, which may contribute to the heightened divalent ion affinity. DSC data indicate that the alpha S55D/E59D variant retains the capacity to bind 1 equiv of Na+. Consistent with this finding, when binding measurements are conducted in K(+)-containing buffer, divalent ion affinity is markedly higher. In 0.15 M KCl and 0.025 M Hepes-KOH (pH 7.4) at 5 degrees C, the macroscopic Ca2+ binding constants are 1.8 x 10(10) and 2.0 x 10(9) M(-1). The corresponding Mg2+ binding constants are 2.7 x 10(6) and 1.2 x 10(5) M(-1).

Amino Acid Substitution↗