Evidence for association of bipolar disorder to haplotypes in the 22q12.3 region near the genes stargazin, IFT27 and parvalbumin

We have previously reported genome-wide significant linkage of bipolar disorder to a region on 22q12.3 near the marker D22S278. Towards identifying the susceptibility gene, we have conducted a fine-mapping association study of the region in two independent family samples, an independent case-control sample and a genome-wide association dataset. Two hundred SNPs were first examined in a 5 Mb region surrounding the D22S278 marker in a sample of 169 families and analyzed using PLINK. The peak of association was a haplotype near the genes stargazin (CACNG2), intraflagellar transport protein homolog 27 (IFT27) and parvalbumin (PVALB; P = 4.69 × 10(-4)). This peak overlapped a significant haplotype in a family based association study of a second independent sample of 294 families (P = 1.42 × 10(-5)). Analysis of the combined family sample yielded statistically significant evidence of association to a rare three SNP haplotype in the gene IFT27 (P = 8.89 × 10(-6)). Twelve SNPs comprising these haplotypes were genotyped in an independent sample of 574 bipolar I cases and 550 controls. Statistically significant association was found for a haplotype window that overlapped the region from the first two family samples (P = 3.43 × 10(-4)). However, analyses of the two family samples using the program LAMP, found no evidence for association in this region, but did yield significant evidence for association to a haplotype 3' of CACNG2 (P = 1.76 × 10(-6)). Furthermore, no evidence for association was found in a large genome-wide association dataset. The replication of association to overlapping haplotypes in three independent datasets suggests the presence of a bipolar disorder susceptibility gene in this region.

Melatonin regulates the calcium-buffering proteins, parvalbumin and hippocalcin, in ischemic brain injury

Melatonin has anti-oxidant activity and it exerts a neuroprotective effects during ischemic brain injury. Calcium-buffering proteins including parvalbumin and hippocalcin are involved in neuronal differentiation and maturation through calcium signaling. This study investigated whether melatonin moderates parvalbumin and hippocalcin expression in cerebral ischemia and glutamate toxicity-induced neuronal cell death. Focal cerebral ischemia was induced by middle cerebral artery occlusion (MCAO). Male Sprague-Dawley rats were treated with vehicle or melatonin (5 mg/kg) prior to MCAO, and cerebral cortical tissues were collected 24 hr after MCAO. Parvalbumin and hippocalcin levels were decreased in vehicle-treated animal with MCAO, whereas melatonin prevented the ischemic injury-induced reduction in these proteins. In cultured hippocampal cells, glutamate toxicity decreased parvalbumin and hippocalcin levels, while melatonin treatment prevented the glutamate exposure-induced diminished in these proteins levels. Melatonin also attenuated the glutamate toxicity-induced increase in intracellular Ca(2+) levels. These results suggest that the maintenance of parvalbumin and hippocalcin levels by melatonin in ischemic injury contributes to the neuroprotective effect of melatonin against neuronal cell damage.

The absence of the calcium-buffering protein calbindin is associated with faster age-related decline in hippocampal metabolism

Although reductions in the expression of the calcium-buffering proteins calbindin D-28K (CB) and parvalbumin (PV) have been observed in the aging brain, it is unknown whether these changes contribute to age-related hippocampal dysfunction. To address this issue, we measured basal hippocampal metabolism and hippocampal structure across the lifespan of C57BL/6J, calbindin D-28k knockout (CBKO) and parvalbumin knockout (PVKO) mice. Basal metabolism was estimated using steady state relative cerebral blood volume (rCBV), which is a variant of fMRI that provides the highest spatial resolution, optimal for the analysis of individual subregions of the hippocampal formation. We found that like primates, normal aging in C57BL/6J mice is characterized by an age-dependent decline in rCBV-estimated dentate gyrus (DG) metabolism. Although abnormal hippocampal fMRI signals were observed in CBKO and PVKO mice, only CBKO mice showed accelerated age-dependent decline of rCBV-estimated metabolism in the DG. We also found age-independent structural changes in CBKO mice, which included an enlarged hippocampus and neocortex as well as global brain hypertrophy. These metabolic and structural changes in CBKO mice correlated with a deficit in hippocampus-dependent learning in the active place avoidance task. Our results suggest that the decrease in CB that occurs during normal aging is involved in age-related hippocampal metabolic decline. Our findings also illustrate the value of using multiple MRI techniques in transgenic mice to investigate mechanisms involved in the functional and structural changes that occur during aging.

PGC-1α induces mitochondrial and myokine transcriptional programs and lipid droplet and glycogen accumulation in cultured human skeletal muscle cells

The transcriptional coactivator peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α) is a chief activator of mitochondrial and metabolic programs and protects against atrophy in skeletal muscle (skm). Here we tested whether PGC-1α overexpression could restructure the transcriptome and metabolism of primary cultured human skm cells, which display a phenotype that resembles the atrophic phenotype. An oligonucleotide microarray analysis was used to reveal the effects of PGC-1α on the whole transcriptome. Fifty-three different genes showed altered expression in response to PGC-1α: 42 upregulated and 11 downregulated. The main gene ontologies (GO) associated with the upregulated genes were mitochondrial components and processes and this was linked with an increase in COX activity, an indicator of mitochondrial content. Furthermore, PGC-1α enhanced mitochondrial oxidation of palmitate and lactate to CO₂, but not glucose oxidation. The other most significantly associated GOs for the upregulated genes were chemotaxis and cytokine activity, and several cytokines, including IL-8/CXCL8, CXCL6, CCL5 and CCL8, were within the most highly induced genes. Indeed, PGC-1α highly increased IL-8 cell protein content. The most upregulated gene was PVALB, which is related to calcium signaling. Potential metabolic regulators of fatty acid and glucose storage were among mainly regulated genes. The mRNA and protein level of FITM1/FIT1, which enhances the formation of lipid droplets, was raised by PGC-1α, while in oleate-incubated cells PGC-1α increased the number of smaller lipid droplets and modestly triglyceride levels, compared to controls. CALM1, the calcium-modulated δ subunit of phosphorylase kinase, was downregulated by PGC-1α, while glycogen phosphorylase was inactivated and glycogen storage was increased by PGC-1α. In conclusion, of the metabolic transcriptome deficiencies of cultured skm cells, PGC-1α rescued the expression of genes encoding mitochondrial proteins and FITM1. Several myokine genes, including IL-8 and CCL5, which are known to be constitutively expressed in human skm cells, were induced by PGC-1α.

Convergent differential regulation of parvalbumin in the brains of vocal learners

Spoken language and learned song are complex communication behaviors found in only a few species, including humans and three groups of distantly related birds – songbirds, parrots, and hummingbirds. Despite their large phylogenetic distances, these vocal learners show convergent behaviors and associated brain pathways for vocal communication. However, it is not clear whether this behavioral and anatomical convergence is associated with molecular convergence. Here we used oligo microarrays to screen for genes differentially regulated in brain nuclei necessary for producing learned vocalizations relative to adjacent brain areas that control other behaviors in avian vocal learners versus vocal non-learners. A top candidate gene in our screen was a calcium-binding protein, parvalbumin (PV). In situ hybridization verification revealed that PV was expressed significantly higher throughout the song motor pathway, including brainstem vocal motor neurons relative to the surrounding brain regions of all distantly related avian vocal learners. This differential expression was specific to PV and vocal learners, as it was not found in avian vocal non-learners nor for control genes in learners and non-learners. Similar to the vocal learning birds, higher PV up-regulation was found in the brainstem tongue motor neurons used for speech production in humans relative to a non-human primate, macaques. These results suggest repeated convergent evolution of differential PV up-regulation in the brains of vocal learners separated by more than 65–300 million years from a common ancestor and that the specialized behaviors of learned song and speech may require extra calcium buffering and signaling.

[Cloning, expression and purification of allergen parvalbumin from Aristichthys nobilis and its allergic activity]

OBJECTIVE

To clone, express and identify the parvalbumin gene from Aristichthys nobilis, and investigate its allergenicity.

METHODS

The parvalbumin gene was amplified by RT-PCR and cloned into PMD18-T for sequencing and analysis. Then the target gene was subcloned into pET-28a (+) for expression in E. coli BL21 (DE3) by IPTG induction. The recombinant protein was purified by metal (Ni2+) chelating affinity chromatography. Its allergenicity was examined by Western-blotting assay.

RESULTS

The length of gene (Accession No. FJ013047) was 330 bp, coding 109 amino acids. The E. coli strain could express a recombinant protein with a molecular weight of 11 537 Da. The recombinant allergen was identified as its affinity to specific IgE antibodies from the allergic patient sera by Western-blotting.

CONCLUSION

The parvalbumin gene from Aristichthys nobilis is successfully cloned and expressed in this study, and the recombinant protein possesses good IgE-binding capacity.

PVALB, a new Hürthle adenoma diagnostic marker identified through gene expression

CONTEXT

A better means to accurately identify malignant thyroid nodules and to distinguish them from benign tumors is needed. We previously identified markers for detecting thyroid malignancy, with sensitivity estimated at or close to 100%. One lingering problem with these markers was that false positives occurred with Hürthle cell adenomas (HCA) which lowered test specificity.

METHODS

To locate accurate diagnostic markers, we profiled in depth the transcripts of a HCA and a Hürthle cell carcinoma (HCC). From 1146 differentially expressed genes, 18 transcripts specifically expressed in HCA were tested by quantitative PCR in a wide range of thyroid tumors (n = 76). Sensibility and specificity were calculated using receiver operating characteristic (ROC). Selected markers were further validated in an independent set of thyroid tumors (n = 82) by immunohistochemistry. To define the panel that would yield best diagnostic accuracy, these markers were tested in combination with our previous identified markers.

RESULTS

Seventeen of the 18 genes showed statistical significance based on a mean relative level of expression (P < 0.05). KLK1 (sensitivity = 0.97) and PVALB (sensitivity = 0.94) were the best candidate markers. The combination of PVALB and C1orf24 increased specificity to >97% and maintained sensitivity for detection of carcinoma.

CONCLUSION

We identified tumor markers that can be used in combination for a more accurate preoperative diagnosis of thyroid nodules and for postoperative diagnosis of thyroid carcinoma in tumor sections. This improved test would help physicians rapidly focus treatment on true malignancies and avoid unnecessary treatment of benign tumors, simultaneously improving medical care and reducing costs.

Purification and characterization of parvalbumins from silver carp (Hypophthalmichthy molitrix)

BACKGROUND

As the largest producer and consumer of freshwater fish in the world, many people suffer from allergy for consuming freshwater fish in China. However, the allergen profiles of freshwater fish are rarely known.

RESULTS

Parvalbumins (PVs) from the white muscle of silver carp (Hypophthalmichthy molitrix) were purified by ammonium sulfate fractionation and column chromatography including DEAE-Sepharose and Superdex 75. Three PV isoforms-PV-I, PV-II, and PV-III-were obtained and their molecular masses as estimated by tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis were 12, 11, and 14 kDa, respectively. All the PVs could be detected by anti-frog PV monoclonal antibody. PV-I and PV-II were quite possibly glycoproteins, while PV-III was not glycosylated, as analyzed by periodic acid-Schiff (PAS) staining. Thermal stability revealed that PV-I and PV-II easily formed polymers, while these proteins were stable in a pH range of 4.0-10.0. A PV gene encoding 110 amino acid residues was cloned and it revealed high identity with PVs from other species of fish.

CONCLUSION

Three isotypes of PV were purified to homogeneity and one distinct PV gene was cloned in silver carp white muscle.

Opposite effect of phencyclidine on activity-regulated cytoskeleton-associated protein (Arc) in juvenile and adult limbic rat brain regions

The psychotomimetic effect of NMDA antagonists such as phencyclidine (PCP) in humans spurred the hypoglutamatergic theory of schizophrenia. This theory is supported by animal studies demonstrating schizophrenia-like behavioral and molecular changes following PCP administration to adult or neonatal animals. However, schizophrenia is believed to develop in part due to neurodevelopmental dysfunction during adolescence. Therefore, the effects of PCP in juvenile animals may better reflect the pathophysiology of schizophrenia. Here, we compare the effect of PCP (5mg/kg/day for 5 days) on activity-regulated cytoskeleton-associated protein (Arc) and parvalbumin mRNA expression in juvenile and adult rats. Arc is a marker for excitatory neurotransmission. Parvalbumin is a marker for GABAergic neurotransmission, known to be reduced in postmortem brains of schizophrenics. PCP reduced parvalbumin mRNA expression in the medial prefrontal cortex (mPFC), ventrolateral orbitofrontal cortex (VLO) and shell of the nucleus accumbens (ACCshell) in both juvenile and adult rats. Contrarily, PCP produced opposite effects on Arc mRNA expression in the mPFC, VLO and ACCshell, leading to decreased expression in juvenile and increased expression in adult rats. The differential effect of PCP in juvenile and adult rats may be caused by the immature functional state of the prefrontal cortex in juvenile rats. These results demonstrate differences between the effects of PCP in juvenile and adult rats. The decrease in Arc mRNA in juvenile rats corresponds best with the proposed "hypofrontality" in schizophrenia, suggesting the merits of using PCP in juvenile animals as a model for schizophrenia, as this would relate better to the typical onset and clinical features of schizophrenia.

Characterisation of purified parvalbumin from five fish species and nucleotide sequencing of this major allergen from Pacific pilchard, Sardinops sagax

IgE-mediated allergic reaction to seafood is a common cause of food allergy including anaphylactic reactions. Parvalbumin, the major fish allergen, has been shown to display IgE cross-reactivity among fish species consumed predominantly in Europe and the Far East. However, cross-reactivity studies of parvalbumin from fish species widely consumed in the Southern hemisphere are limited as is data relating to immunological and molecular characterisation. In this study, antigenic cross-reactivity and the presence of oligomers and isomers of parvalbumin from five highly consumed fish species in Southern Africa were assessed by immunoblotting using purified parvalbumin and crude fish extracts. Pilchard (Sardinops sagax) parvalbumin was found to display the strongest IgE reactivity among 10 fish-allergic consumers. The cDNA sequence of the beta-form of pilchard parvalbumin was determined and designated Sar sa 1.0101 (accession number FM177701 EMBL/GenBank/DDBJ databases). Oligomeric forms of parvalbumin were observed in all fish species using a monoclonal anti-parvalbumin antibody and subject's sera. Isoforms varied between approximately 10-13 kDa. A highly cross-reactive allergenic isoform of parvalbumin was identified and sequenced, providing a successful primary step towards the generation of a recombinant form that could be used for diagnostic and potential therapeutic use in allergic individuals.

Deficits in adult prefrontal cortex neurons and behavior following early post-natal NMDA antagonist treatment

The prefrontal cortex (PFC) is associated with higher cognitive functions including attention and working memory and has been implicated in the regulation of impulsivity as well as the pathology of complex mental illnesses. N-methyl D-aspartate (NMDA) antagonist treatment with dizocilpine induces cell death which is greatest in the frontal cortex on post-natal day seven (P7), however the long-term structural and behavioral effects of this treatment are unknown. This study investigates both the acute neurotoxicity of P7 dizocilpine and the persistent effects of this treatment on pyramidal cells and parvalbumin interneurons in the adult PFC, a brain region involved in the regulation of impulsivity. Dizocilpine treatment on P7 increased cleaved caspase-3 immunoreactivity (IR) in the PFC on P8. In adult mice (P82), P7 dizocilpine treatment resulted in 50% fewer parvalbumin-positive interneurons (p<0.01) and 42% fewer layer V pyramidal neurons (p<0.01) in the PFC. Double immunohistochemistry revealed cleaved caspase-3 IR in both GAD67 IR interneurons and GAD67 (-) neurons. Following dizocilpine treatment at P7, adults showed reduced time in the center of the open field suggesting increased anxiety-like behavior. These findings indicate that early brain insults affecting glutamatergic neurotransmission lead to persistent brain pathology that could contribute to impulsivity and cognitive dysfunction.

Detection of parvalbumin, a common fish allergen gene in food, by real-time polymerase chain reaction

Fish, as one of the most common causes of IgE-mediated food hypersensitivity, has recently received increasing attention from the food industry and legislative and regulatory agencies. A real-time polymerase chain reaction assay based on TaqMan-MGB probe technology was developed for the detection of parvalbumin, a major fish allergen gene. The assay had a sensitivity up to 5 pg purified fish DNA and had no cross-reaction with other species, such as cattle, sheep, swine, chicken, shrimp, lobster, crab, squid, clam, rice, soybean, maize, and potato. The coefficient of variation for both intra- and interexperimental variability demonstrated high reproducibility and accuracy. The assay proved to be a potential tool for the detection and label management of fish allergens in food.

The continuing disappearance of "pure" Ca2+ buffers

Advances in the understanding of a class of Ca(2+)-binding proteins usually referred to as "Ca(2+) buffers" are reported. Proteins historically embraced within this group include parvalbumins (alpha and beta), calbindin-D9k, calbindin-D28k and calretinin. Within the last few years a wealth of data has accumulated that allow a better understanding of the functions of particular family members of the >240 identified EF-hand Ca(2+)-binding proteins encoded by the human genome. Studies often involving transgenic animal models have revealed that they exert their specific functions within an intricate network consisting of many proteins and cellular mechanisms involved in Ca(2+) signaling and Ca(2+) homeostasis, and are thus an essential part of the Ca(2+) homeostasome. Recent results indicate that calbindin-D28k, possibly also calretinin and oncomodulin, the mammalian beta parvalbumin, might have additional Ca(2+) sensor functions, leaving parvalbumin and calbindin-D9k as the only "pure" Ca(2+) buffers.

A neonatal ventral hippocampal lesion causes functional deficits in adult prefrontal cortical interneurons

Animals with a neonatal ventral hippocampal lesion (NVHL) develop abnormal behaviors during or after adolescence, suggesting that early insults can have delayed consequences. Many of these behaviors depend on the prefrontal cortex (PFC), and we have reported that PFC pyramidal neurons of adult rats with an NVHL respond to stimulation of the ventral tegmental area with an increase in firing instead of the characteristic decrease. As the dopamine modulation of cortical interneurons matures during adolescence, these findings raise the possibility that maturation of local inhibitory circuits within the PFC may have been altered in NVHL rats. Here, we assessed the state of PFC interneurons in NVHL rats with in situ hybridization measures of the mRNAs for the calcium binding protein parvalbumin (PV) and the GABA synthesizing enzyme GAD(67), as well as with electrophysiological measures of interneuron function. Although no differences were observed with PV or GAD(67), whole-cell recordings in slices revealed abnormal responses to the D(2) agonist quinpirole in interneurons from NVHL rats. The loss of D(2) modulation of local inhibition in slices from NVHL rats was also evident in the absence of a lasting component in the D(2) attenuation of excitatory synaptic responses in pyramidal neurons, which in sham treated rats was picrotoxin sensitive. The results suggest that the neonatal lesion causes improper maturation, but not loss, of PFC interneurons during adolescence, a finding consistent with current interpretations of imaging data in schizophrenia that suggest a hyperactive, "noisy" cortex underlying dysfunction in the PFC and other cortical areas.

Combining molecular dynamics and machine learning to improve protein function recognition

As structural genomics efforts succeed in solving protein structures with novel folds, the number of proteins with known structures but unknown functions increases. Although experimental assays can determine the functions of some of these molecules, they can be expensive and time consuming. Computational approaches can assist in identifying potential functions of these molecules. Possible functions can be predicted based on sequence similarity, genomic context, expression patterns, structure similarity, and combinations of these. We investigated whether simulations of protein dynamics can expose functional sites that are not apparent to the structure-based function prediction methods in static crystal structures. Focusing on Ca2+ binding, we coupled a machine learning tool that recognizes functional sites, FEATURE, with Molecular Dynamics (MD) simulations. Treating molecules as dynamic entities can improve the ability of structure-based function prediction methods to annotate possible functional sites.

Solution structure of Ca2+-free rat beta-parvalbumin (oncomodulin)

Relative to other parvalbumin isoforms, the mammalian beta-parvalbumin (oncomodulin) displays attenuated divalent ion affinity. High-resolution structural data for the Ca(2+)-bound protein have provided little insight into the physical basis for this behavior, prompting an examination of the unliganded state. This article describes the solution structure and peptide backbone dynamics of Ca(2+)-free rat beta-parvalbumin (beta-PV). Ca(2+) removal evidently provokes significant structural alterations. Interaction between the D helix and the AB domain in the Ca(2+)-bound protein is greatly diminished in the apo-form, permitting the D helix to straighten. There is also a significant reorganization of the hydrophobic core and a concomitant remodeling of the interface between the AB and CD-EF domains. These modifications perturb the orientation of the C and D helices, and the energetic penalty associated with their reversal could contribute to the low-affinity signature of the CD site. By contrast, Ca(2+) removal causes a comparatively minor perturbation of the E and F helices, consistent with the more typical divalent ion affinity observed for the EF site. Ca(2+)-free rat beta-PV retains structural rigidity on the picosecond-nanosecond timescale. At 20 degrees C, the majority of amide vectors show no evidence for motion on timescales above 20 ps, and the average order parameter for the entire molecule is 0.92.

Inhibition and synchronization of basal amygdala principal neuron spiking by parvalbumin-positive interneurons

Using mice that express enhance green fluorescent protein (EGFP) under the control of the parvalbumin promoter, we made paired recordings from interneurons and principal neurons in the basal amygdala. In synaptically connected pairs, we show that single action potentials in a parvalbumin expressing interneuron can inhibit spiking in the synaptically connected principal neuron. When principal neurons were provided with suprathreshold oscillatory drive via a somatic patch pipette, action potentials in the interneuron inhibited spiking in principal neurons only when the interneuron spike occurred shortly before excitation reached threshold in the principal neuron. Moreover, after this spike inhibition, there was a rebound excitation in the principal neurons that was seen as an increased probability of firing on the cycle after inhibition. These results illustrate the major role of local inhibition in the basal amygdala. We propose that these interneurons in the basal amygdala provide a potent inhibition that acts to inhibit firing of principal neurons during cortically driven oscillations.

Molecular cloning, expression and phylogenetic analyses of parvalbumin in tilapia, Oreochromis mossambicus

The gene expression of parvalbumin (Pvalb), a high-affinity calcium-binding protein and the major fish allergen, was significantly increased in the tilapia fry treated with methyltestosterone (MT) as examined using a subtractive hybridization assay. Using the real-time quantitative PCR, we further confirmed the increased Pvalb expression in the MT-treated tilapia fry. The 568 base pairs (bp) tilapia Pvalb (tPvalb) cDNA clone was fully sequenced and found to contain a coding region of 330 bp, which encodes a 108 amino acids protein with a molecular weight of 11,370.5 and an calculated isoelectric point of 4.56. The predicted secondary structure of tPvalb is comprised of seven alpha helices. It contains two characteristic EF-hand calcium-binding motifs, one PKC and five casein kinase II consensus phosphorylation sites. The tPvalb is highly homologous to the selected fish Pvalbs at a similarity ranging from 53% to 80%. The phylogenetic tree analysis showed that the tPvalb is closest to the Scomber japonicus Pvalb. The tPvalb was found to express in the heart, muscle, gill, kidney, brain and ovary of adult fish by RT-PCR analysis. In situ hybridization also revealed that the tPvalb was highly expressed in the hypothalamus and sarcoplasmic reticulum. A tPvalb glutathione S-transferase (GST) fusion protein was generated and digested by thrombin to remove the GST moiety. Further Western analysis showed that the tPvalb protein was cross-reacted to an anti-rat Pvalb antibody. Those results suggest that Pvalb is evolutionally conserved in tilapia.

Developmental regulation of the membrane properties of central vestibular neurons by sensory vestibular information in the mouse

The effect of the lack of vestibular input on the membrane properties of central vestibular neurons was studied by using a strain of transgenic, vestibular-deficient mutant KCNE1(-/-) mice where the hair cells of the inner ear degenerate just after birth. Despite the absence of sensory vestibular input, their central vestibular pathways are intact. Juvenile and adult homozygous mutant have a normal resting posture, but show a constant head bobbing behaviour and display the shaker/waltzer phenotype characterized by rapid bilateral circling during locomotion. In juvenile mice, the KCNE1 mutation was associated with a strong decrease in the expression of the calcium-binding proteins calbindin, calretinin and parvalbumin within the medial vestibular nucleus (MVN) and important modifications of the membrane properties of MVN neurons. In adult mice, however, there was almost no difference between the membrane properties of MVN neurons of homozygous and control or heterozygous mutant mice, which have normal inner ear hair cells and show no behavioural symptoms. The expression levels of calbindin and calretinin were lower in adult homozygous mutant animals, but the amount of calcium-binding proteins expressed in the MVN was much greater than in juvenile mice. These data demonstrate that suppression of sensory vestibular inputs during a 'sensitive period' around birth can generate the circling/waltzing behaviour, but that this behaviour is not due to persistent abnormalities of the membrane properties of central vestibular neurons. Altogether, maturation of the membrane properties of central vestibular neurons is delayed, but not impaired by the absence of sensory vestibular information.

A recombinant hypoallergenic parvalbumin mutant for immunotherapy of IgE-mediated fish allergy

IgE-mediated allergy to fish is a frequent cause of severe anaphylactic reactions. Parvalbumin, a small calcium-binding protein, is the major fish allergen. We have recently isolated a cDNA coding for carp parvalbumin, Cyp c 1, and expressed in Escherichia coli a recombinant Cyp c 1 molecule, which contained most IgE epitopes of saltwater and freshwater fish. In this study, we introduced mutations into the calcium-binding domains of carp parvalbumin by site-directed mutagenesis and produced in E. coli three parvalbumin mutants containing amino acid exchanges either in one (single mutants; Mut-CD and Mut-EF) or in both of the calcium-binding sites (double mutant; Mut-CD/EF). Circular dichroism analyses of the purified derivatives and the wild-type allergen showed that Mut-CD/EF exhibited the greatest reduction of overall protein fold. Dot blot assays and immunoblot inhibition experiments performed with sera from 21 fish-allergic patients showed that Mut-CD/EF had a 95% reduced IgE reactivity and represented the derivative with the least allergenic activity. The latter was confirmed by in vitro basophil histamine release assays and in vivo skin prick testing. The potential applicability for immunotherapy of Mut-CD/EF was demonstrated by the fact that mouse IgG Abs could be raised by immunization with the mutated molecule, which cross-reacted with parvalbumins from various fish species and inhibited the binding of fish-allergic patients' IgE to the wild-type allergen. Using the hypoallergenic carp parvalbumin mutant Mut-CD/EF, it may be possible to treat fish allergy by immunotherapy.

Parvalbumin isoforms differentially accelerate cardiac myocyte relaxation kinetics in an animal model of diastolic dysfunction

The cytosolic Ca(2+)/Mg(2+)-binding protein alpha-parvalbumin (alpha-Parv) has been shown to accelerate cardiac relaxation; however, beyond an optimal concentration range, alpha-Parv can also diminish contractility. Mathematical modeling suggests that increasing Parv's Mg(2+) affinity may lower the effective concentration of Parv ([Parv]) to speed relaxation and, thus, limit Parv-mediated depressed contraction. Naturally occurring alpha/beta-Parv isoforms show divergence in amino acid primary structure (57% homology) and cation-binding affinities, with beta-Parv having an estimated 16% greater Mg(2+) affinity and approximately 200% greater Ca(2+) affinity than alpha-Parv. We tested the hypothesis that, at the same or lower estimated [Parv], mechanical relaxation rate would be more significantly accelerated by beta-Parv than by alpha-Parv. Dahl salt-sensitive (DS) rats were used as an experimental model of diastolic dysfunction. Relaxation properties were significantly slowed in adult cardiac myocytes isolated from DS rats compared with controls: time from peak contraction to 50% relaxation was 57 +/- 2 vs. 49 +/- 2 (SE) ms (P < 0.05), validating this model system. DS cardiac myocytes were subsequently transduced with alpha- or beta-Parv adenoviral vectors. Upon Parv gene transfer, beta-Parv caused significantly faster relaxation than alpha-Parv (P < 0.05), even though estimated [beta-Parv] was approximately 10% of [alpha-Parv]. This comparative analysis showing distinct functional outcomes raises the prospect of utilizing naturally occurring Parv variants to address disease-associated slowed cardiac relaxation.

Age-related changes in parvalbumin-positive interneurons in the striatum, but not in the sensorimotor cortex in dystonic brains of the dt mutant hamster

In the dt(sz) hamster, a model of paroxysmal dystonia, an age-dependent increase in the activity of striatal projection neurons has been hypothesized to be based on a deficit of striatal parvalbumin-immunoreactive (PV(+)) interneurons at an age of most marked expression of dystonia (30-40 days of life). In the present study, the spontaneous age-dependent remission of paroxysmal dystonia in older dt(sz) hamsters (age>90 days) was found to coincide with a normalization of the density of striatal PV(+) interneurons. Furthermore, the arborization of these interneurons was lower in 31 day old dt(sz) hamsters, but was even higher in dt(sz) mutant at an age of >90 days than in control animals. Double-labeling with bromodeoxyuridine failed to show a retarded proliferation, while the number of interneurons with strong expression of PV mRNA was lower in young mutant hamsters. As shown by unaltered density of PV(+) interneurons in sensorimotor cortex of 31 day old dt(sz) hamsters, PV containing interneurons are not reduced throughout the whole brain at the sensitive age. The present data suggest that a retarded postnatal maturation of striatal PV(+) interneurons plays a critical role in paroxysmal dystonia.

Parvalbumin is a mobile presynaptic Ca2+ buffer in the calyx of Held that accelerates the decay of Ca2+ and short-term facilitation

Presynaptic Ca2+ signaling plays a crucial role in short-term plasticity of synaptic transmission. Here, we studied the role of mobile endogenous presynaptic Ca2+ buffer(s) in modulating paired-pulse facilitation at a large excitatory nerve terminal in the auditory brainstem, the calyx of Held. To do so, we assessed the effect of presynaptic whole-cell recording, which should lead to the diffusional loss of endogenous mobile Ca2+ buffers, on paired-pulse facilitation and on intracellular Ca2+ concentration ([Ca2+]i) transients evoked by action potentials. In unperturbed calyces briefly preloaded with the Ca2+ indicator fura-6F, the [Ca2+]i transient decayed surprisingly fast (tau(fast), approximately 30 ms). Presynaptic whole-cell recordings made without additional Ca2+ buffers slowed the decay kinetics of [Ca2+]i and paired-pulse facilitation (twofold to threefold), but the amplitude of the [Ca2+]i transient was changed only marginally. The fast [Ca2+]i decay was restored by adding the slow Ca2+ buffer EGTA (50-100 microM) or parvalbumin (100 microM), a Ca2+-binding protein with slow Ca2+-binding kinetics, to the presynaptic pipette solution. In contrast, the fast Ca2+ buffer fura-2 strongly reduced the amplitude of the [Ca2+]i transient and slowed its decay, suggesting that the mobile endogenous buffer in calyces of Held has slow, rather than fast, binding kinetics. In parvalbumin knock-out mice, the decay of [Ca2+]i and facilitation was slowed approximately twofold compared with wild-type mice, similar to what is observed during whole-cell recordings in rat calyces of Held. Thus, in young calyces of Held, a mobile Ca2+ buffer with slow binding kinetics, primarily represented by parvalbumin, accelerates the decay of spatially averaged [Ca2+]i and paired-pulse facilitation.

Networks of parvalbumin-positive interneurons in the basolateral amygdala

The amygdala is a temporal lobe structure that is required for processing emotional information. Polymodal sensory information enters the amygdala at the level of the basolateral amygdala (BLA) and undergoes local processing, after which the behavioral and autonomic responses that accompany emotions are initiated. Two main neuron types are present in the BLA, pyramidal-like principal neurons that use glutamate as their transmitter, and local circuit interneurons that use GABA as their transmitter. Although the properties of principal neurons are known in some detail, very little is known about the properties of BLA interneurons or the local circuits in which they are involved. Using mice in which EGFP (enhanced green fluorescent protein) is expressed under the control of the parvalbumin promoter, we characterized the properties of parvalbumin-positive interneurons in the BLA. By making recordings from interneuron-interneuron and interneuron-principal neuron pairs, we analyzed the intrinsic circuitry of the BLA. We show that parvalbumin-positive interneurons can be divided into four subtypes as defined by their firing properties. Interneurons are electrically coupled in subtype-specific networks and exhibit subtype-specific heterogeneities in their synaptic dynamics and patterns of connectivity. We propose that these properties allow networks of parvalbumin-expressing neurons to perform an array of information-processing tasks within the BLA.

Differences in locomotor behavior revealed in mice deficient for the calcium-binding proteins parvalbumin, calbindin D-28k or both

We investigated the role of the two calcium-binding proteins parvalbumin (PV) and calbindin D-28k (CB) in the locomotor activity and motor coordination using null-mutant mice for PV (PV-/-), CB (CB-/-) or both proteins (PV-/-CB-/-). These proteins are expressed in distinct, mainly non-overlapping populations of neurons of the central and peripheral nervous system and PV additionally in fast-twitch muscles. In a test measuring repeated locomotor activity during 18-20 days, the analysis revealed a slightly increased activity in mice lacking either protein, while the lack of both decreased the number of beams crossed during active periods. An increase in the characteristic speed during the first 8 days could be attributed to PV-deficiency, while the elimination of CB in CB-/- and double-KO mice decreased the percentage of fast movements at all time points. In the latter, additionally a reduction of the fastest speed was observed. The alterations in locomotor activity (fast movements, fastest speed) strongly correlate with the impairment in locomotor coordination in mice deficient for CB evidenced in the runway assay and the rotarod assay. The graded locomotor phenotype (CB>PV) is qualitatively correlated with alterations in Purkinje cell firing reported previously in these mice. The presence or absence of either protein did not affect the spontaneous locomotor activity when animals were placed in a novel environment and tested only once for 30 min. In summary, the lack of these calcium-binding proteins yields characteristic, yet distinct phenotypes with respect to locomotor activity and coordination.