Ca Binding Protein Research Articles

Ca(2+)-sensors and ROS-GC: interlocked sensory transduction elements: a review.

From its initial discovery that ROS-GC membrane guanylate cyclase is a mono-modal Ca2+-transduction system linked exclusively with the photo-transduction machinery to the successive finding that it embodies a remarkable bimodal Ca2+ signaling device, its widened transduction role in the general signaling mechanisms of the sensory neuron cells was envisioned. A theoretical concept was proposed where Ca2+-modulates ROS-GC through its generated cyclic GMP via a nearby cyclic nucleotide gated channel and creates a hyper- or depolarized sate in the neuron membrane (Ca2+ Binding Proteins 1:1, 7–11, 2006). The generated electric potential then becomes a mode of transmission of the parent [Ca2+]i signal. Ca2+ and ROS-GC are interlocked messengers in multiple sensory transduction mechanisms. This comprehensive review discusses the developmental stages to the present status of this concept and demonstrates how neuronal Ca2+-sensor (NCS) proteins are the interconnected elements of this elegant ROS-GC transduction system. The focus is on the dynamism of the structural composition of this system, and how it accommodates selectivity and elasticity for the Ca2+ signals to perform multiple tasks linked with the SENSES of vision, smell, and possibly of taste and the pineal gland. An intriguing illustration is provided for the Ca2+ sensor GCAP1 which displays its remarkable ability for its flexibility in function from being a photoreceptor sensor to an odorant receptor sensor. In doing so it reverses its function from an inhibitor of ROS-GC to the stimulator of ONE-GC membrane guanylate cyclase.

Three functional facets of calbindin D-28k

Many neurons of the vertebrate central nervous system (CNS) express the Ca2+ binding protein calbindin D-28k (CB), including important projection neurons like cerebellar Purkinje cells but also neocortical interneurons. CB has moderate cytoplasmic mobility and comprises at least four EF-hands that function in Ca2+ binding with rapid to intermediate kinetics and affinity. Classically it was viewed as a pure Ca2+ buffer important for neuronal survival. This view was extended by showing that CB is a critical determinant in the control of synaptic Ca2+ dynamics, presumably with strong impact on plasticity and information processing. Already 30 years ago, in vitro studies suggested that CB could have an additional Ca2+ sensor function, like its prominent acquaintance calmodulin (CaM). More recent work substantiated this hypothesis, revealing direct CB interactions with several target proteins. Different from a classical sensor, however, CB appears to interact with its targets both, in its Ca2+-loaded and Ca2+-free forms. Finally, CB has been shown to be involved in buffered transport of Ca2+, in neurons but also in kidney. Thus, CB serves a threefold function as buffer, transporter and likely as a non-canonical sensor.

Accelerated Recovery of L-Type Ca Current Contributes to the Loss of SR Ca Release Restitution in Mice Lacking Casq2

Cardiac Ca-release from sarcoplasmic reticulum (SR) is reduced with successively shorter coupling intervals of premature stimuli, a phenomenon known as SR Ca-release restitution. Interestingly, myocytes lacking the SR luminal Ca binding protein calsequestrin (Casq2 KO) lack SR Ca-release restitution. Here we test whether altered L-type Ca current (ICa) responsible for triggering SR Ca-release contributes to the loss of Ca-release restitution.Results: ICa was recorded in voltage-clamped ventricular myocytes isolated from Casq2 KO mice and wild-type (WT) littermates. Cells were pre-treated with ryanodine and thapsigargin to eliminate SR Ca-release. After a 1 Hz train of depolarizing stimuli (S1), ICa restitution was measured by applying premature stimuli (S2) at successively shorter S1-S2 coupling intervals. Both groups have decreased ICa at short S1-S2 intervals, but ICa recovered significantly faster in KO vs. WT myocytes (p<0.001, Figure). Eliciting Ca-release by ICa tail currents (which eliminates participation of ICa restitution) reduced the difference between WT and KO Ca-release restitutions.Conclusion: Accelerated recovery of ICa contributes to loss of SR Ca-release restitution in mice lacking Casq2 and may further increase risk for ventricular arrhythmia in vivo.View Large Image | View Hi-Res Image | Download PowerPoint Slide

Comparative Examination of Inner Ear in Wild Type and Pituitary Adenylate Cyclase Activating Polypeptide (PACAP)-Deficient Mice

Pituitary adenylate cyclase activating polypeptide (PACAP) is a multifunctional neuropeptide with well-known neuroprotective and neurotrophic effects. The involvement of PACAP in sensory processing has also been documented, but little is known about its effects in the auditory system. PACAP and its specific receptor (PAC1) are present in the cochlea and in brain structures involved in auditory pathways. Recently, we have shown that PACAP protects cochlear cells against oxidative stress-induced apoptosis. The endolymphatic Ca(2+) concentration controlled by Ca(2+) buffers of the hair cells is essential for the normal hearing processes. In this study we examined the localization of PAC1 receptor and Ca(2+) buffering proteins (parvalbumin, calretinin, calbindin) in the inner ear of 5-day-old PACAP-deficient mice compared with wild-type mice in order to get a closer insight into the effect of endogenous PACAP in the cochlear function. We did not find differences in the distribution pattern of PAC1 receptors between the two groups, but wild-type animals showed significantly higher PAC1 receptor expression. In contrast, inner and outer hair cells of PACAP-deficient mice showed more pronounced parvalbumin, calbindin, and calretinin immunopositivity compared with wild-type mice. Elevated endolymphatic Ca(2+) is deleterious for cochlear function, while the high concentration of Ca(2+) buffers in hair cells may offer protection. The increased immunoreactivity of Ca(2+) binding proteins in the absence of PACAP provide further evidence the important role of PACAP in the hearing processes.

Calsequestrin 2 and arrhythmias

Calsequestrin is the most abundant Ca-binding protein of the specialized endoplasmic reticulum found in muscle, the sarcoplasmic reticulum (SR). Calsequestrin binds Ca with high capacity and low affinity and importantly contributes to the mobilization of Ca during each contraction both in skeletal and cardiac muscle. Surprisingly, mutations in the gene encoding the cardiac isoform of calsequestrin (Casq2) have been associated with an inherited form of ventricular arrhythmia triggered by emotional or physical stress termed catecholaminergic polymorphic ventricular tachycardia (CPVT). Despite normal cardiac contractility and normal resting ECG, CPVT patients present with a high risk of sudden death at a young age. Here, we review recent new insights regarding the role of calsequestrin in genetic and acquired arrhythmia disorders. Mouse models of CPVT have shed light on the pathophysiological mechanism underlying CPVT. Casq2 is not only a Ca-storing protein as initially hypothesized, but it has a far more complex function in Ca handling and regulating SR Ca release channels. The functional importance of Casq2 interactions with other SR proteins and the importance of alterations in Casq2 trafficking are also being investigated. Reports of altered Casq2 trafficking in animal models of acquired heart diseases such as heart failure suggest that Casq2 may contribute to arrhythmia risk beyond genetic forms of Casq2 dysfunction.

Abstract P084: Cardiac-Specific Overexpression of Human Histidine-Rich Calcium Binding Protein (HRC-S96A) Genetic Variant Impairs Sarcoplasmic Ca 2+ Handling, Resulting in Arrhythmias

Disturbed Ca-homeostasis in the cardiomyocyte is a hallmark of human and experimental heart failure. The histidine-rich Ca binding protein (HRC), an intraluminal SR protein is an additional regulator of SR Ca2+ cycling. Previous biochemical studies have shown that HRC can bind to triadin (a component of ryanodine receptors complex) and SERCA2a, suggesting that HRC may be involved in the regulation of SR Ca2+ release and Ca2+ uptake. We recently identified a human HRC genetic variant (S96A), which appears to correlate with ventricular arrhythmias and sudden death in dilated cardiomyopathy (DCM) patients. To gain insight into the physiological and pathological significance of the S96A-HRC variant, we generated transgenic mice with cardiac-specific overexpression of human HRC wild-type (HRC-WT) and S96A mutant (HRC-S96A) in the HRC null (HRC KO) background. We obtained lines with similar expression levels of HRC-S96A and HRC-WT for further characterization. Overexpression of human HRC-S96A resulted in decreased fractional shortening by 22% (7.7 ± 0.5% in HRC-WTs vs. 6.0 ± 0.4% in HRC-S96A), rates of contraction by 20% (75 ± 5 µm/sec in HRC-WTs vs. 60 ± 4 µm/sec in HRC-S96A) and rates of relaxation by 20% (87 ± 6 µm/sec in HRC-WTs vs. 70 ± 4.5 µm/sec in HRC-S96A) compared with HRC-WT. Myocytes isolated from HRC-S96A mice had diminished Ca2+ transient amplitude and delayed half-decay time of the Ca2+ transient. In addition, the frequency of Ca2+ sparks was significantly higher although caffeine-induced SR Ca2+ release (SR load) was reduced in HRC-S96A cells. To determine the effect of S96A-HRC under stress conditions, 5 Hz field stimulation in the presence of 1 µmol/L Isoproterenol was applied: after-contractions were developed in 46% (16 of 35) of HRC-S96A cardiomyocytes, compared to 12% (4 of 33) of HRC-WTs mice. The findings of the present study demonstrate that the human HRC-S96A variant results in impaired myocytes Ca2+ handling, associated with depressed SR Ca2+-uptake rate and increased rate of SR Ca2+ leak, which may destabilize the cells, promoting aftercontractions under stress conditions. Thus, there appears to be a link between this genetic variant and ventricular arrhythmias in DCM human carriers.

Lessons from calsequestrin-1 ablation in vivo: much more than a Ca2+ buffer after all

Calsequestrin type-1 (CASQ1), the main sarcoplasmic reticulum (SR) Ca(2+) binding protein, plays a dual role in skeletal fibers: a) it provides a large pool of rapidly-releasable Ca(2+) during excitation-contraction (EC) coupling; and b) it modulates the activity of ryanodine receptors (RYRs), the SR Ca(2+) release channels. We have generated a mouse lacking CASQ1 in order to further characterize the role of CASQ1 in skeletal muscle. Contrary to initial expectations, CASQ1 ablation is compatible with normal motor activity, in spite of moderate muscle atrophy. However, CASQ1 deficiency results in profound remodeling of the EC coupling apparatus: shrinkage of junctional SR lumen; proliferation of SR/transverse-tubule contacts; and increased density of RYRs. While force development during a twitch is preserved, it is nevertheless characterized by a prolonged time course, likely reflecting impaired Ca(2+) re-uptake by the SR. Finally, lack of CASQ1 also results in increased rate of SR Ca(2+) depletion and inability of muscle to sustain tension during a prolonged tetani. All modifications are more pronounced (or only found) in fast-twitch extensor digitorum longus muscle compared to slow-twitch soleus muscle, likely because the latter expresses higher amounts of calsequestrin type-2 (CASQ2). Surprisingly, male CASQ1-null mice also exhibit a marked increased rate of spontaneous mortality suggestive of a stress-induced phenotype. Consistent with this idea, CASQ1-null mice exhibit an increased susceptibility to undergo a hypermetabolic syndrome characterized by whole body contractures, rhabdomyolysis, hyperthermia and sudden death in response to halothane- and heat-exposure, a phenotype remarkably similar to human malignant hyperthermia and environmental heat-stroke. The latter findings validate the CASQ1 gene as a candidate for linkage analysis in human muscle disorders.

Characterisation of the interaction of the C-terminus of the dopamine D2 receptor with neuronal calcium sensor-1.

NCS-1 is a member of the neuronal calcium sensor (NCS) family of EF-hand Ca2+ binding proteins which has been implicated in several physiological functions including regulation of neurotransmitter release, membrane traffic, voltage gated Ca2+ channels, neuronal development, synaptic plasticity, and learning. NCS-1 binds to the dopamine D2 receptor, potentially affecting its internalisation and controlling dopamine D2 receptor surface expression. The D2 receptor binds NCS-1via a short 16-residue cytoplasmic C-terminal tail. We have used NMR and fluorescence spectroscopy to characterise the interactions between the NCS-1/Ca2+ and D2 peptide. The data show that NCS-1 binds D2 peptide with a Kd of ∼14.3 µM and stoichiometry of peptide binding to NCS-1 of 2∶1. NMR chemical shift mapping confirms that D2 peptide binds to the large, solvent-exposed hydrophobic groove, on one face of the NCS-1 molecule, with residues affected by the presence of the peptide spanning both the N and C-terminal portions of the protein. The NMR and mutagenesis data further show that movement of the C-terminal helix 11 of NCS-1 to fully expose the hydrophobic groove is important for D2 peptide binding. Molecular docking using restraints derived from the NMR chemical shift data, together with the experimentally-derived stoichiometry, produced a model of the complex between NCS-1 and the dopamine receptor, in which two molecules of the receptor are able to simultaneously bind to the NCS-1 monomer.

Changes in the Levels of Neurospecific Proteins and in Behavioral Phenomena in Rats with Hepatic Encephalopathy

We showed that, under conditions of experimental chronic hepatitis, excessive increases in the levels of a Ca-binding protein, S-100b, and a neuronal cell adhesion molecule, NCAM, occur in all parts of the brain of Wistar rats. This is accompanied by suppression of locomotor and orientational/research activity of the animals and increase in their stress sensitivity. Treatment by α ketoglutarate and cytoflavin in chronic hepatitis provides a clear neuroprotective effect.

Overexpression of histidine-rich calcium binding protein in equine ventricular myocardium

Histidine-rich calcium binding protein (HRC) is a high capacity, low affinity Ca(2+) binding protein, specifically expressed in striated muscles of mammals. In rabbit skeletal and cardiac muscles, HRC binds to sarcoplasmic reticulum (SR) membranes via triadin, a junctional SR protein. Recently, a potential role in heart failure and arrhythmogenesis has been assigned to HRC due to its activity as regulator of SR Ca(2+) uptake and Ca(2+) release. HRC might play a particularly relevant role in the equine heart, given its slower resting heart rate (20-35 beats/min) and longer action potential duration (APD) (0.6-1.0 s) than are found in other mammals. The results from this study showed for the first time direct evidence that HRC protein in equine cardiac muscle was expressed in association with the SR membranes and that HRC transcriptional activity was three times higher in the ventricles compared to the atria. The predominance of HRC mRNA up-regulation in ventricular myocardium was specific to the horse heart, since a more even distribution between atria and ventricles was found in animals of similar body size or species, such as cattle or domestic donkeys.

Dietary fructose inhibits lactation‐induced adaptations in rat 1,25‐(OH) 2 D 3 synthesis and calcium transport

We recently showed that excessive fructose consumption, already associated with numerous metabolic abnormalities, reduces rates of intestinal Ca(2+) transport. Using a rat lactation model with increased Ca(2+) requirements, we tested the hypothesis that mechanisms underlying these inhibitory effects of fructose involve reductions in renal synthesis of 1,25-(OH)(2)D(3). Pregnant and virgin (control) rats were fed isocaloric fructose or, as controls, glucose, and starch diets from d 2 of gestation to the end of lactation. Compared to virgins, lactating dams fed glucose or starch had higher rates of intestinal transcellular Ca(2+) transport, elevated intestinal and renal expression of Ca(2+) channels, Ca(2+)-binding proteins, and CaATPases, as well as increased levels of 25-(OH)D(3) and 1,25-(OH)(2)D(3). Fructose consumption prevented almost all of these lactation-induced increases, and reduced vitamin D receptor binding to promoter regions of Ca(2+) channels and binding proteins. Changes in 1,25-(OH)(2)D(3) level were tightly correlated with alterations in expression of 1α-hydroxylase but not with levels of parathyroid hormone and of 24-hydroxylase. Bone mineral density, content, and mechanical strength each decreased with lactation, but then fructose exacerbated these effects. When Ca(2+) requirements increase during lactation or similar physiologically challenging conditions, excessive fructose consumption may perturb Ca(2+) homeostasis because of fructose-induced reductions in synthesis of 1,25-(OH)(2)D(3).

Generation of a comprehensive panel of crustacean allergens from the North Sea Shrimp Crangon crangon

BackgroundPublished data on crustacean allergens are incomplete. The identification of tropomyosin (TM), arginine kinase (AK), sarcoplasmic Ca-binding protein (SCP) and myosin light chain (MLC) as shrimp allergens are all important contributions but additional allergens are required for the development of a complete set of reagents for component resolved diagnosis and the exploration of novel vaccination strategies. MethodsThe North Sea shrimp (Crangon crangon), which is frequently consumed in Europe, served as a model organism in this study. TM and AK were directly cloned from mRNA based on sequence homology and produced as recombinant proteins. Additional IgE-reactive proteins were isolated by preparative SDS-PAGE and identified by mass spectrometry and corresponding cDNAs were cloned and expressed in E. coli. The relevance of the 6 cloned crustacean allergens was confirmed with sera of 31 shrimp-allergic subjects, 12 of which had a positive double-blind, placebo-controlled food challenge (DBPCFC) to shrimp and 19 a convincing history of food allergy to shrimp, including 5 cases of anaphylaxis. Quantitative IgE measurements were performed by ImmunoCAP. ResultsSix recombinant crustacean proteins: TM, AK, SCP, a novel MLC, troponin C (TnC), and triosephosphate isomerase (TIM) bound IgE in ImmunoCAP analysis. Specific IgE to at least one of these single shrimp allergens was detected in 90% of the study population, thus the in vitro diagnostic sensitivity was comparable to that of shrimp extract (97%). In 75% of the subjects, the combined technical sensitivity was similar to or greater with single shrimp allergens than with natural shrimp extract. ConclusionsWe identified six IgE-binding proteins from C. crangon, three of which have not before been described as allergens in crustaceans. This extensive panel of shrimp allergens forms a valuable asset for future efforts towards the identification of clinically relevant biomarkers and as a basis to approach patient-tailored immunotherapeutic strategies.

Neurospora crassa homologue of Neuronal Calcium Sensor-1 has a role in growth, calcium stress tolerance, and ultraviolet survival

NCU04379 gene encodes a conserved Ca(2+) and/or calmodulin binding protein that possesses a consensus signal for N-terminal myristoylation and four EF-hands, characteristics of Neuronal Calcium Sensor-1proteins. The NCU04379.2 knockout mutant shows slow growth rate, increased sensitivity to calcium and ultraviolet (UV) irradiation, and a wild-type fragment carrying NCU04379 gene complements the mutant. Therefore, NCU04379 gene has a role in growth, calcium stress tolerance, and UV survival. Crosses homozygous for ΔNCU04379.2 mutant strains were fully fertile; however, we found evidence for involvement of Ca(2+)/calmodulin-dependent protein kinase encoding genes NCU02283 and NCU09123 in sexual development.

Ca2+ homeostasis defects and hereditary hearing loss

Ca(2+) acts as a fundamental signal transduction element in inner ear, delivering information about sound, acceleration and gravity through a small number of mechanotransduction channels in the hair cell stereocilia and voltage activated Ca(2+) channels at the ribbon synapse, where it drives neurotransmission. The mechanotransduction process relies on the endocochlear potential, an electrical potential difference between endolymph and perilymph, the two fluids bathing respectively the apical and basolateral membrane of the cells in the organ of Corti. In mouse models, deafness and lack or reduction of the endocochlear potential correlate with ablation of connexin (Cx) 26 or 30. These Cxs form heteromeric channels assembled in a network of gap junction plaques connecting the supporting and epithelial cells of the organ of Corti presumably for K(+) recycle and transfer of key metabolites, for example, the Ca(2+) -mobilizing second messenger IP(3) . Ca(2+) signaling in these cells could play a crucial role in regulating Cx expression and function. Another district where Ca(2+) signaling alterations link to hearing loss is hair cell apex, where ablation or missense mutations of the PMCA2 Ca(2+) -pump of the stereocilia cause deafness and loss of balance. If less Ca(2+) is exported from the stereocilia, as in the PMCA2 mouse mutants, Ca(2+) concentration in endolymph is expected to fall causing an alteration of the mechanotransduction process. This may provide a clue as to why, in some cases, PMCA2 mutations potentiated the deafness phenotype induced by coexisting mutations of cadherin-23 (Usher syndrome type 1D), a single pass membrane Ca(2+) binding protein that is abundantly expressed in the stereocilia.

Analysis of a salinity induced BjSOS3 protein from Brassica indicate it to be structurally and functionally related to its ortholog from Arabidopsis

Arabidopsis has been a favorite model system for plant biologist. It is anticipated that comparative analysis of this plant with other members of Brassicaceae may aid in identification of orthologs playing role as key genetic determinants for salinity response. In this endeavor, we have recently identified SOS family members from Brassica juncea in our laboratory and reported their salinity responsive transcriptional induction in seedlings of various diploid and amphidiploids species. In the present study, we have carried out detailed time kinetics for BjSOS3 expression in a salinity tolerant B.juncea var. CS52. Transcript analysis at the sensitive growth stages of plants viz. seedling and reproductive stage indicated clear differential transcriptional regulation of BjSOS3 under non-induced as well as salinity induced conditions in a time and organ specific manner, mirroring their respective tolerance physiology. Similar to its ortholog from Arabidopsis thaliana, the modeled BjSOS3 protein show typical features of a Ca(2+) binding protein with four conserved EF-hands. We have also attempted to study the binding of SOS3 protein with the modeled SOS2 protein. It has been established that SOS3 protein senses Ca(2+) though the binding is very weak; we show the down regulation of BjSOS3 mRNA in presence of calcium chelator - EGTA under the various stress conditions including ABA. In situ localization of BjSOS3-GFP fusion protein in onion peel has shown its presence strongly in plasma membrane as well as cytosol. The leads presented in the paper will assist in understanding and establishing the SOS signaling machinery in B.juncea.

Calmodulin as a direct detector of Ca2+ signals

Many forms of signal transduction occur when Ca2+ enters the cytoplasm of a cell. It has been generally thought that there is a fast buffer that rapidly reduces the free Ca2+ level and that it is this buffered level of Ca2+ that triggers downstream biochemical processes, notably the activation of calmodulin (CaM) and the resulting activation of CaM-dependent enzymes. Given the importance of these transduction processes, it is critical to understand exactly how Ca2+ triggers CaM. We have determined the rate at which Ca2+ binds to calmodulin (CaM) and found that Ca2+ binds more rapidly than to other Ca2+-binding proteins. This property of CaM and its high concentration argue for a new view of signal transduction: CaM directly intercepts incoming Ca2+ and sets the free Ca2+ levels (i.e., strongly contributes to fast Ca2+ buffering) rather than responding to the lower Ca2+ level set by other buffers. This property is critical for making CaM an efficient transducer. Our results also suggest a new role for other Ca2+ binding proteins (CBPs) in regulating the lifetime of Ca2+ bound to CaM, thereby setting the gain of signal transduction.

Duplication of calsequestrin genes in teleosts: Molecular characterization in the Senegalese sole (Solea senegalensis)

Calsequestrin is a moderate-affinity, high-capacity Ca(2+) binding protein in the sarcoplasmic reticulum of skeletal and cardiac muscle that seems to act as an intralumenal Ca(2+) buffer. Two different isoforms have been described in mammals, the skeletal and cardiac isoforms, encoded by CASQ1 and CASQ2 genes, respectively. In this study, we present molecular phylogenetic evidence of a gene duplication event of both calsequestrin genes in teleosts, referred to as casq1a/casq1b and casq2a/casq2b. We obtained the entire cDNAs encoding the four genes in the Senegalese sole (Solea senegalensis Kaup). Main features and sequence identities with other fish and mammalian calsequestrins are described. Expression profiles during larval development and in juvenile tissues were analyzed using a real-time PCR approach. In juvenile fish, casq1a and casq1b were highly expressed in skeletal muscle, whereas the highest casq2a and casq2b transcript levels were detected in heart and brain, respectively. During metamorphosis, casq2a and casq1b expression remained unchanged. In contrast, casq1a and casq2b mRNAs exhibited a continuous increase from the beginning of metamorphosis until post-metamorphosis. Transcriptional regulation of casq1 and casq2 genes by thyroid hormones (THs) was also evaluated. Larvae exposed to the goitrogen thiourea (TU) exhibited higher casq1a mRNA levels than untreated control, whereas expression of the remaining genes did not vary significantly. Moreover, addition of exogenous T4 hormone to TU-treated larvae increased the casq1a steady-state levels with respect to the untreated control at metamorphosis climax. Comprehensively, these results demonstrate the existence of four calsequestrin genes in teleosts differentially regulated by THs.

The Evolution of Milk Casein Genes from Tooth Genes before the Origin of Mammals

Caseins are among cardinal proteins that evolved in the lineage leading to mammals. In milk, caseins and calcium phosphate (CaP) form a huge complex called casein micelle. By forming the micelle, milk maintains high CaP concentrations, which help altricial mammalian neonates to grow bone and teeth. Two types of caseins are known. Ca-sensitive caseins (α(s)- and β-caseins) bind Ca but precipitate at high Ca concentrations, whereas Ca-insensitive casein (κ-casein) does not usually interact with Ca but instead stabilizes the micelle. Thus, it is thought that these two types of caseins are both necessary for stable micelle formation. Both types of caseins show high substitution rates, which make it difficult to elucidate the evolution of caseins. Yet, recent studies have revealed that all casein genes belong to the secretory calcium-binding phosphoprotein (SCPP) gene family that arose by gene duplication. In the present study, we investigated exon-intron structures and phylogenetic distributions of casein and other SCPP genes, particularly the odontogenic ameloblast-associated (ODAM) gene, the SCPP-Pro-Gln-rich 1 (SCPPPQ1) gene, and the follicular dendritic cell secreted peptide (FDCSP) gene. The results suggest that contemporary Ca-sensitive casein genes arose from a putative common ancestor, which we refer to as CSN1/2. The six putative exons comprising CSN1/2 are all found in SCPPPQ1, although ODAM also shares four of these exons. By contrast, the five exons of the Ca-insensitive casein gene are all reminiscent of FDCSP. The phylogenetic distribution of these genes suggests that both SCPPPQ1 and FDCSP arose from ODAM. We thus argue that all casein genes evolved from ODAM via two different pathways; Ca-sensitive casein genes likely originated directly from SCPPPQ1, whereas the Ca-insensitive casein genes directly differentiated from FDCSP. Further, expression of ODAM, SCPPPQ1, and FDCSP was detected in dental tissues, supporting the idea that both types of caseins evolved as Ca-binding proteins. Based on these findings, we propose two alternative hypotheses for micelle formation in primitive milk. The conserved biochemical characteristics in caseins and their immediate ancestors also suggest that many slight genetic modifications have created modern caseins, proteins vital to the sustained success of mammals.

Immunohistochemical study on the expression of calcium binding proteins (calbindin-D28k, calretinin, and parvalbumin) in the cerebral cortex and in the hippocampal region of nNOS knock-out(-/-) mice

Nitric oxide (NO) modulates the activities of various channels and receptors to participate in the regulation of neuronal intracellular Ca2+ levels. Ca2+ binding protein (CaBP) expression may also be altered by NO. Accordingly, we examined expression changes in calbindin-D28k, calretinin, and parvalbumin in the cerebral cortex and hippocampal region of neuronal NO synthase knockout(-/-) (nNOS-/-) mice using immunohistochemistry. For the first time, we demonstrate that the expression of CaBPs is specifically altered in the cerebral cortex and hippocampal region of nNOS-/- mice and that their expression changed according to neuronal type. As changes in CaBP expression can influence temporal and spatial intracellular Ca2+ levels, it appears that NO may be involved in various functions, such as modulating neuronal Ca2+ homeostasis, regulating synaptic transmission, and neuroprotection, by influencing the expression of CaBPs. Therefore, these results suggest another mechanism by which NO participates in the regulation of neuronal Ca2+ homeostasis. However, the exact mechanisms of this regulation and its functional significance require further investigation.

Cocaine and amphetamine regulated transcript, type-2 vesicular glutamate transporter and calbindin co-expression define spiny stellate cells in layer IV of the granular cerebral cortex

Event Abstract Back to Event Cocaine and amphetamine regulated transcript, type-2 vesicular glutamate transporter and calbindin co-expression define spiny stellate cells in layer IV of the granular cerebral cortex C. S. Molnár1, M. Sárvári1, I. Kalló2, Z. Liposits1, 2 and E. Hrabovszky1* 1 Hungarian Academy of Sciences, Institute of Experimental Medicine, Hungary 2 Pázmány Péter Catholic University, Department of Neuroscience, Hungary Microarray experiments from our laboratory identified cocaine and amphetamine regulated transcript (CART) as an estrogen-regulated cortical gene. The present studies addressed the anatomical location and functional phenotype of cortical CART neurons using immunohistochemical (IHC) and in situ hybridization (ISH) strategies. IHC and ISH studies localized CART expressing neurons in layer IV throughout the granular cortex of the rat. CART neurons were found to be distinct from GABAergic interneurons expressing glutamic acid decarboxylase-65 mRNA. Out of the Ca-binding proteins calretinin, parvalbumin and calbindin, CART neurons only expressed low levels of calbindin. ISH studies established that the distribution of CART/calbindin neurons was identical with that of VGLUT2 mRNA expressing cells in layer IV. Morphological studies with IHC determined that CART/VGLUT2/calbindin neurons correspond to spiny stellate cells known to establish local efferent cortical connections. Future studies will use electrophysiological tools to address the effects of CART on cortical neuronal functioning and molecular approaches to study the regulation of cortical CART expression under various physiological and pathological conditions. Acknowledgements This work was supported by grants from the Hungarian Scientific Research Fund (OTKA K69127 T73002 and K83710), the Hungarian Health Research Council Fund (ETT 122/2009) and the European Community's Seventh Framework Programme (FP7/2007-2013; grant agreement n° 245009). Keywords: Molecular and cellular neurobiology, Neuroscience Conference: 13th Conference of the Hungarian Neuroscience Society (MITT), Budapest, Hungary, 20 Jan - 22 Jan, 2011. Presentation Type: Abstract Topic: Molecular and cellular neurobiology Citation: Molnár CS, Sárvári M, Kalló I, Liposits Z and Hrabovszky E (2011). Cocaine and amphetamine regulated transcript, type-2 vesicular glutamate transporter and calbindin co-expression define spiny stellate cells in layer IV of the granular cerebral cortex. Front. Neurosci. Conference Abstract: 13th Conference of the Hungarian Neuroscience Society (MITT). doi: 10.3389/conf.fnins.2011.84.00001 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 03 Mar 2011; Published Online: 23 Mar 2011. * Correspondence: Dr. E. Hrabovszky, Hungarian Academy of Sciences, Institute of Experimental Medicine, Budapest, Hungary, hrabovszky.erik@koki.mta.hu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers C. S Molnár M. Sárvári I. Kalló Z. Liposits E. Hrabovszky Google C. S Molnár M. Sárvári I. Kalló Z. Liposits E. Hrabovszky Google Scholar C. S Molnár M. Sárvári I. Kalló Z. Liposits E. Hrabovszky PubMed C. S Molnár M. Sárvári I. Kalló Z. Liposits E. Hrabovszky Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.