Expression Of calbindin-D28k Research Articles

Expression of calbindin-D28k is inversely correlated with proapototic gene expression in hydrogen peroxide-induced cell death in endometrial cancer cells

Calbindin-D28k (CaBP-28k) is a calcium binding protein important for intracellular Ca2+ buffering and known to have anti-apoptotic properties in neurons, osteoblasts and male germ cells. Although endometrial cancer is a common invasive gynecologic malignancy, the involvement of uterine CaBP-28k in apoptotic signaling of endometrial cancer is poorly understood. The present study investigates the role of CaBP-28k in hydrogen peroxide (H2O2)-induced apoptotic signaling in human endometrial Ishikawa cells. The dose- and time-dependent effect of H2O2 on Bax, p53 and Bcl-2 expression was assessed by Western blot analysis. Treatment of cells with 1 mM H2O2 for 1 h induced an increase in Bax and p53 expression, but the expression of Bcl-2 was not affected by H2O2 treatment. Interestingly, overexpression of CaBP-28k inhibited cell death and caused a decrease in Bax, p53 and caspase 3 expression during H2O2-induced apoptosis, suggesting that CaBP-28k blocks the up-regulation of apoptosis-related gene expression. siRNA knockdown of CaBP-28k resulted in an elevation of H2O2-induced cell death and an increase in Bax, p53 and caspase 3, providing additional evidence that induction of the CaBP-28k gene might be associated with survival signaling during H2O2-mediated cell death. Overall, these results suggest that CaBP-28k expression is inversely correlated with pro-apoptotic gene expression in human endometrial Ishikawa cells.

Expression of the Calbindin-d28k Protein and Gene in Human Ovary

Objective To investigate expression and localization of Calbindin-d28k (CaBP-d28k) in human ovary. Methods The expression of the CaBP-d28k protein and gene in 23 human ovarian samples was measured by immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR) methods. Results Positive expression of the CaBP-d28k protein and mRNA was observed in human ovary. The ovarian expression of the CaBP-d28k protein appeared in the cytoplasm of oocytes, granulose cells, theca cells, and two types of cells of corpus luteum. From primordial follicle, primary follicle to secondary follicle, increased CaBP-d28k levels were showed (P Conclusion Human ovarian tissue locally expresses CaBP-d28k, and its expression level increases with follicular development.

Expression of Calbindin-D28k in Human Endometrium During Menstrual Cycle.

Expression of Calbindin-D28k in Human Endometrium During Menstrual Cycle.

C-Ret–mediated hearing loss in mice with Hirschsprung disease

A significantly increased risk for dominant sensorineural deafness in patients who have Hirschsprung disease (HSCR) caused by endothelin receptor type B and SOX10 has been reported. Despite the fact that c-RET is the most frequent causal gene of HSCR, it has not been determined whether impairments of c-Ret and c-RET cause congenital deafness in mice and humans. Here, we show that impaired phosphorylation of c-Ret at tyrosine 1062 causes HSCR-linked syndromic congenital deafness in c-Ret knockin (KI) mice. The deafness involves neurodegeneration of spiral ganglion neurons (SGNs) with not only impaired phosphorylation of Akt and NF-kappaB but decreased expression of calbindin D28k in inner ears. The congenital deafness involving neurodegeneration of SGNs in c-Ret KI mice was rescued by introducing constitutively activated RET. Taken together with our results for three patients with congenital deafness with c-RET-mediated severe HSCR, our results indicate that c-Ret and c-RET are a deafness-related molecule in mice and humans.

Differential changes in cerebellar transmitter content and expression of calcium binding proteins and transcription factors in mouse administered with amphetamine

Cerebellar mechanisms were explored underlying the effects of amphetamine (Amph) on the brain, by monitoring primarily the neurochemistry of the cerebellum. Adult mice received repeated intermittent injections of d-Amph, 5 mg/kg or saline, twice daily for three days and once on day 4. As revealed by the biochemical analysis, the levels of GABA content were increased by 68–93% in the cerebellar vermis and hemisphere of mice at 4 h after the first (acute) or the last (repeated) Amph injections, though the glutamate content was unaltered, compared to the respective saline-treated controls. By contrast, at 4 h post-repeated Amph, in the vermis, the level of norepinephrine was approximate 38% lower than the corresponding control and 5-hydroxytryptamine (5-HT) resembled the control, whereas in the hemisphere, the norepinephrine content was similar to control and 5-HT 66% higher, implying cerebellar lobe-dependent changes. However, in both lobes, at 4 h after the acute and repeated Amph exposures, changes of the transmitter content were correlated with reductions of 50–64% in the levels of the phosphorylated (p) MAP kinase (K) expression and 39–55% in the calbindin-D28k (CB) of the Purkinje cell somata, and increases of 289–556% in pCREB, 373–594% c-FOS, and 51–76% calretinin of the granular layer, as shown by immunohistochemical analysis. The up-regulated GABA content in the vermis and hemisphere may be associated with the decreased expression of Purkinje somatal CB and pMAPK, implicating a relation between the Ca 2+ of Purkinje cells and the level of GABA. Furthermore, the prominent increases of the granular layer pCREB, c-FOS and calretinin may influence the activity of Purkinje cells, which are known to be modulated by the granule cells. The data indicate that the Amph exposure selectively alters specific transmitters in the cerebellar lobes and modifies the cellular expression of distinct signaling proteins in the cerebellar layers.

Evidence for the involvement of calbindin D28k in the presenilin 1 model of Alzheimer's disease

Pathological hallmarks of Alzheimer's disease include memory deficits, accumulation of amyloid beta (Aβ) plaques, the appearance of neurofibrillary tangles, and dysregulation of calcium homeostasis, which has been linked to mutations in the presenilin gene that code for presenilin (PS) proteins. PSs are a family of multi-pass transmembrane proteins where normal presenilins (PS1 and PS2) are highly localized in the endoplasmic reticulum (ER). Several past studies have explored alterations in long-term potentiation (LTP), a proposed molecular correlate of memory, and in behavioral tests of spatial memory in a variety of PS1 models. These reports suggest that calcium plays a role in these alterations, but mechanistic explanations for changes in LTP and in behavioral tests of memory are still lacking. To test the hypothesis that calcium-related mechanisms, such as changes in calcium buffering, are associated with alterations in LTP and memory, we utilized in vitro experimental paradigms of LTP in hippocampal slices obtained from the PS1-M146V transgenic mouse model of Alzheimer's disease (AD). We also used the in vivo Morris water maze (MWM), a test for hippocampal dependent spatial memory. In addition, we used cellular assays to explore molecular mechanisms. We confirm that PS1 mutations (M146V) enhance LTP. We also find increases in some parameters of the MWM, and alterations in other parameters, such as path length indicating impairment in cognitive functioning in PS1-M146V mice. In addition, these findings are observed in association with increased calbindin D28K expression in the CA1 hippocampus of PS1-M146V mice.

Cloning, comparative sequence analysis and mRNA expression of calcium-transporting genes in horses

Epithelial calcium transport occurs by paracellular and transcellular mechanisms. Transcellular transport in intestinal and renal epithelia involves several transport proteins, including transient receptor potential vanilloid member 5 (TRPV5), member 6 (TRPV6), calbindin D9k (CB9), calbindin D28k (CB28), sodium calcium exchanger 1 (NCX1), plasma membrane calcium ATPase 1 (PMCA1), and the vitamin D receptor (VDR). We are interested in the horse because of its unique calcium physiology (high blood calcium, high intestinal calcium absorption, high renal excretion of calcium, low vitamin D concentrations), and because horses often have dysregulated calcium balance with various diseases. We cloned the mRNA for equine TRPV5, TRPV6, CB9, CB28, NCX1, PMCA1, and VDR, performed comparative mRNA and protein sequence analysis, and quantified their mRNA expression in the kidney and gastrointestinal tract. Sequence homology for the mRNAs and proteins was high among mammals (>75%), with fish having the lowest homology (<75%). TRPV5, TRPV6, and CB9 expression was higher in the duodenum and proximal jejunum and followed a similar expression pattern. CB28 expression was greatest in the kidney. PMCA1 and NCX1 expression was similar throughout the intestine, but in the kidney PMCA1 expression was higher. Based on our findings, the proximal small intestine is the main site for transcellular calcium transport, with TRPV6 and CB9 serving as the main transport proteins. In the kidney, TRPV6, CB28, and PMCA1 are likely more important. The low VDR expression in the equine small intestine and kidney relative to the large intestine, together with the reported high intestinal absorption and renal excretion of calcium, and low vitamin D concentrations suggests that epithelial calcium transport in horses is not as dependent on vitamin D as in other species.

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

Nitric Oxide (NO) actively participates in the regulation of neuronal intracellular Ca2+ levels by modulating the activity of various channels and receptors. To test the possibility that modulation of Ca2+ buffer protein expression level by NO participates in this regulatory effect, we examined expression of calbindin-D28k, calretinin, and parvalbumin in the cerebellum of neuronal NO synthase knock-out (nNOS(-/-)) mice using immunohistochemistry. We observed that in the cerebellar cortex of the nNOS(-/-) mice, expression of calbindin-D28k and parvalbumin were significantly increased while expression of calretinin was significantly decreased. These results suggest another mechanism by which NO can participate in the regulation of Ca2+ homeostasis.

Zbtb20-Induced CA1 Pyramidal Neuron Development and Area Enlargement in the Cerebral Midline Cortex of Mice

Expression of the transcriptional repressor Zbtb20 is confined to the hippocampal primordium of the developing dorsal midline cortex in mice. Here, we show that misexpression of Zbtb20 converts projection neurons of the subiculum and postsubiculum (dorsal presubiculum) to CA1 pyramidal neurons that are innervated by Schaffer collateral projections in ectopic strata oriens and radiatum. The Zbtb20-transformed neurons express Bcl11B, Satb2, and Calbindin-D28k, which are markers of adult CA1 pyramidal neurons. Downregulation of Zbtb20 expression by RNA interference impairs the normal maturation of CA1 pyramidal neurons resulting in deficiencies in Calbindin-D28k expression and in reduced apical dendritic arborizations in stratum lacunosum moleculare. Overall, the results show that Zbtb20 is required for various aspects of CA1 pyramidal neuron development such as the postnatal extension of apical dendritic arbors in the distal target zone and the subtype differentiation of Calbindin-D28k-positive subsets. They further suggest that Zbtb20 plays a role in arealization of the midline cortex.

Effect of retinal ablation on the expression of calbindin D28k and GABA in the chick optic tectum

The effect of retinal ablation on qualitative and quantitative changes of calbindin D28k and GABA expression in the contralateral optic tectum was studied in young chicks. Fifteen days old chicks had unilateral retinal ablation and after 7 or 15 days, calbindin expression was analyzed by Western blot and immunocytochemistry. Neuronal degeneration was followed by the amino-cupric silver technique. After 15 days, retinal lesions produced a significant decrease in calbindin immunostaining in the neuropil of layers 5-6 and in the somata of neurons from the layers 8 and 10 of the contralateral tectum, being this effect less marked at 7 days post-lesion. Double staining revealed that 50-60% of cells in the layers 8 and 10 were calbindin and GABA positive, 30-45% were only calbindin positive and 5-10% were only GABAergic neurons. Retinal ablation also produced a decrease in the GABA expression at either 7 or 15 days after surgery. At 7 days, dense silver staining was observed in the layers 5-6 from the optic tectum contralateral to the retinal ablation, which mainly represented neuropil that would come from processes of retinal ganglion cells. Tectal neuronal bodies were not stained with silver, although some neurons were surrounded by coarse granular silver deposits. In conclusion, most of calbindin molecules are present in neurons of the tectal GABAergic inhibitory circuitry, whose functioning apparently depends on the integrity of the visual input. A possible role of calbindin in the control of intracellular Ca2+ in neurons of this circuit when the visual transmission arrives to the optic tectum remains to be studied.

Age-related changes in calbindin-D28k, parvalbumin, and calretinin immunoreactivity in the dog main olfactory bulb.

Expression and age-related changes of calbindin-D28k (CB), parvalbumin (PV), and calretinin (CR) in the main olfactory bulb of the dog were investigated by immunohistochemistry and western blot analysis. Neurons that expressed these calcium-binding proteins showed a characteristic laminar distribution. Most of CB-immunoreactive neurons were observed in the glomerular layer (GL) and the inner sublayer of the external plexiform layer (EPL). Most of PV-immunoreactive neurons were observed in the outer sublayer of the EPL. CR-immunoreactive neurons were mainly distributed in the GL and the granule cell layer. With regard to age-related changes, CB-immunoreactive neurons in the GL were stable among all age groups; however, in the EPL they decreased with age. PV-immunoreactive neurons decreased in middle-aged and aged groups. However, CR-immunoreactive neurons were not decreased in middle-aged and aged groups. These results suggest that CB-immunoreactive neurons in the EPL were most sensitive to aging, and that their reduction may be related to aging in the dog.

Gossypium herbaceam Extracts Attenuate Ibotenic Acid-induced Excitotoxicity in Rat Hippocampus

Excitotoxicity is one of the most extensively studied processes of neuronal death and plays an important role in Alzheimer's disease. In the present study, the protective effects of Gossypium herbaceam extracts (GHE) on learning and memory impairment induced by excitatory neurotoxin ibotenic acid were examined in vivo using Morris water maze. Furthermore, neuroprotective effects of GHE were investigated with methods of immunohistochemistry and biochemistry. Our data showed that oral administration with GHE at the doses of 35, 70 and 140 mg/kg exerted an improved effect on the learning and memory impairment in rats induced by intracerebral injection of ibotenic acid. To confirm the precise mechanism of memory improvement by presence of GHE, we further investigated the potential protection on the hippocampus. Our findings suggest that GHE afforded a beneficial inhibition on pro-apoptosis proteins expression following ibotenic acid. Additionally, calcium pump activity and calbindin-D28k expression were dramatically increased after GHE treatment, implicating that the modulation of calcium homeostasis could be involved in the mechanism underlying neuroprotection of GHE against ibotenic acid-induced excitotoxicity. These data suggested that GHE could be a potential agent for preventing or retarding the development or progression of Alzheimer's disease.

Effects of Thiazide on the Expression of TRPV5, Calbindin-D28K, and Sodium Transporters in Hypercalciuric Rats

TRPV5 is believed to play an important role in the regulation of urinary calcium excretion. We assessed the effects of hydrochlorothiazide (HCTZ) on the expression of TRPV5, calbindin-D28K, and several sodium transporters in hypercalciuric rats. Sprague-Dawley rats were divided into 4 groups; control, HCTZ, high salt, and high salt with HCTZ group in experiment 1; control, HCTZ, high calcium (Ca), and high Ca with HCTZ group in experiment 2. To quantitate the expression of TRPV5, calbindin-D28K, and sodium transporters, western blotting was performed. In both experiments, HCTZ significantly decreased urinary calcium excretion. TRPV5 protein abundance decreased in all hypercalciuric rats, and restored by HCTZ in both high salt with HCTZ and high Ca with HCTZ group. Calbindin-D28K protein abundance increased in the high salt and high salt with HCTZ groups, but did not differ among groups in experiment 2. Protein abundance of NHE3 and NKCC2 decreased in all hypercalciuric rats, and were restored by HCTZ in only high Ca-induced hypercalciuric rats. In summary, protein abundance of TRPV5, NHE3, and NKCC2 decreased in all hypercalciuric rats. The hypocalciuric effect of HCTZ is associated with increased protein abundance of TRPV5 in high salt or calcium diet-induced hypercalciuric rats.

The innervation patterns of single subthalamic neurons in rat

Epithelial calcium transport occurs by paracellular and transcellular mechanisms. Transcellular transport in intestinal and renal epithelia involves several transport proteins, including transient receptor potential vanilloid member 5 (TRPV5), member 6 (TRPV6), calbindin D9k (CB9), calbindin D28k (CB28), sodium calcium exchanger 1 (NCX1), plasma membrane calcium ATPase 1 (PMCA1), and the vitamin D receptor (VDR). We are interested in the horse because of its unique calcium physiology (high blood calcium, high intestinal calcium absorption, high renal excretion of calcium, low vitamin D concentrations), and because horses often have dysregulated calcium balance with various diseases. We cloned the mRNA for equine TRPV5, TRPV6, CB9, CB28, NCX1, PMCA1, and VDR, performed comparative mRNA and protein sequence analysis, and quantified their mRNA expression in the kidney and gastrointestinal tract. Sequence homology for the mRNAs and proteins was high among mammals (>75%), with fish having the lowest homology (<75%). TRPV5, TRPV6, and CB9 expression was higher in the duodenum and proximal jejunum and followed a similar expression pattern. CB28 expression was greatest in the kidney. PMCA1 and NCX1 expression was similar throughout the intestine, but in the kidney PMCA1 expression was higher. Based on our findings, the proximal small intestine is the main site for transcellular calcium transport, with TRPV6 and CB9 serving as the main transport proteins. In the kidney, TRPV6, CB28, and PMCA1 are likely more important. The low VDR expression in the equine small intestine and kidney relative to the large intestine, together with the reported high intestinal absorption and renal excretion of calcium, and low vitamin D concentrations suggests that epithelial calcium transport in horses is not as dependent on vitamin D as in other species.

Changes in calbindin-D28k and parvalbumin expression in the superior olivary complex following unilateral cochlear ablation in neonatal rats

Conclusion. Unilateral congenital deafness with a volume reduction in cochlear nucleus (CN) induced changes in the calcium-binding proteins (CaBPs) in the contralateral superior olivary complex (SOC) in the rat. With the loss of neurons and a volume reduction in the CN, a decrease in the input to the contralateral SOC may occur, which results in the down-regulation of CaBPs in these nuclei. This study may provide some implications regarding the neurochemistry in the auditory brainstem of deaf children. Objective. Hearing loss produced by cochlear damage during early development can result in persistent changes in the organization of the central auditory system in adults. The purpose of the present study was to investigate the neurochemical changes produced in the auditory brainstem of rats with unilateral cochlear ablation conducted before the onset of hearing. Materials and methods. Following unilateral cochlear ablation during early development, we examined the changes in the distribution of two CaBPs, calbindin-D28k (CB) and parvalbumin (PV), in the SOC. Results. Upon reaching adulthood, a marked decrease in CB- and PV-immunoreactive neurons was observed in the contralateral SOC, particularly in the medial nucleus of the trapezoid body (MNTB), although no neuronal cell death was observed. A volume reduction in the ipsilateral CN was also observed.

Meso Scale Discovery and Luminex Comparative Analysis of Calbindin D28K

The sensitivity of different renal regions to xenobiotics requires the development of a multiplex immunoassay for the simultaneous analysis of kidney biomarkers. Calbindin D28K is a distal tubule-specific protein that can be detected in urine under pathological conditions. In this study, a pair of anti-calbindin D28K antibodies was used in an immunoassay for the detection of calbindin D28K expression in rat and human kidney and urine. Comparative analysis of the immunoassay was performed on the Meso Scale Development (MSD) and Luminex platforms. Analysis on both platforms detected calbindin D28K concentrations between 100 ng/mL and 100 pg/mL. Luminex detected 10-fold the amount of calbindin D28K in samples analyzed as compared to MSD, whereas calbindin D28K level in rat and human urine was below detection limit in both platforms. The application of the immunoassays described herein may be useful in toxicological and pathological studies of distal tubular damage in rats and human.

Glutamate Receptors GluR1 and GluR4 in the Hamster Superior Colliculus: Distribution and Co-localization with Calcium-Binding Proteins and GABA

We investigated the distributions of AMPA glutamate receptor subtypes GluR1 and GluR4 in the hamster superior colliculus (SC) with antibody immunocytochemistry and the effect of enucleation on these distributions. We compared these labelings to those of GluR2/3 in our previous report (Park et al., 2004, Neurosci Res., 49:139–155) and calcium-binding proteins calbindin D28K, calretinin, parvalbumin, and GABA. Anti-GluR1-immunoreactive (IR) cells were scattered throughout the SC. By contrast, anti-GluR4-IR cells formed distinct clusters within the lower lateral stratum griseum intermediale (SGI) and lateral stratum album intermediale (SAI). The GluR1- and GluR4-IR neurons varied in size and morphology. The average diameter of the GluR1-IR cells was 13.00 µm, while the GluR4-IR cells was 20.00 µm. The large majority of IR neurons were round or oval cells, but they also included stellate, vertical fusiform and horizontal cells. Monocular enucleation appeared to have no effect on the GluR1 and GluR4 immunoreactivity. Some GluR1-IR cells expressed calbindin D28K (9.50%), calretinin (6.59%), parvalbumin (2.53%), and GABA (20.54%). By contrast, no GluR4-IR cells expressed calcium-binding proteins or GABA. Although the function of the AMPA receptor subunits in SC is not yet clear, the distinct segregation of the GluR subunits, its differential colocalization with calcium-binding proteins and GABA, and differential responses to enucleation suggest the functional diversity of the receptor subunits in visuo-motor integration in the SC.

The expression and implication of TRPV5, calbindin-D28k and NCX1 in idiopathic hypercalciuria

The expression of calcium epithelium TRPV5, alcium binding protein Calbindin-D28k and Na(+)/Ca(2+) exchanger NCX1 was detected in renal distal convoluted tubule, and their effects on urine calcium reabsorption and the possible pathogenic mechanism in idiopathic hypercalciuria (IH) were investigated. Genetic hypercalciuric stone-forming (GHS) rats were chosen as animal models to study urine calcium reabsorption and IH. The cognate female and male rats that had maximal urine calcium were matched to breed next generation. Twelve GHS rats and 12 normal control (NC) SD rats were selected. Western blot and real time quantitative PCR were used to detect the protein and gene expression of TRPV5, Calbindin-D28k and NCX1 respectively. The expression levels of TRPV5 protein and mRNA in GHS rats were significantly lower than in NC rats (P<0.05). Western blot revealed that the expression levels of Calbindin-D28k in GHS rats and NC rats were 0.49+/-0.02 and 0.20+/-0.01 respectively, with the difference being significant between them (P<0.05). By using real time quantitative PCR, it was found that there was no significant difference in Calbindin-28k mRNA expression levels between GHS rats and NC rats (P>0.05). There was no significant difference in the NCX1 expression between GHS rats and NC rats (P>0.05). It was suggested that TRPV5 and Calbindin-D28k might play an important role in urine calcium reabsorption and IH, but they differently contributed to the pathogenesis: The down-regulation of TRPV5 decreases urine calcium reabsorption, directly leading to loss of the urine calcium and resulting in hypercalciuria, and the increased Calbindin-D28k expression could relieve, neutralize and decrease intracellular Ca(2+) concentration to maintain calcium balance. NCX1 is not the key protein in urine calcium reabsorption.

Calbindin-D28K expression induced by glial cell line-derived neurotrophic factor in substantia nigra neurons dependent on PI3K/Akt/NF-κB signaling pathway

Calbindin-D28K is a calcium-binding protein in neuronal cytoplasm, which has the capability to protect neurons from degeneration. It was reported that glial cell line-derived neurotrophic factor (GDNF) increased calbindin-D28K expression in dopaminergic neurons in vitro. It was observed in our research that GDNF also enhanced the expression of calbindin-D28K in adult rat substantia nigra neurons in vivo. To investigate the intracellular signaling pathways underlying the calbindin-D28K expression induced by GDNF, immunoblot and immunoprecipitation analyses were performed in our present study. Our results showed that injection of GDNF alone into substantia nigra of an adult rat brain increased the calbindin-D28K expression; meanwhile, the phosphorylation level of protein kinase B (Akt) and extracellular signal-regulated kinase 1/2 (ERK1/2) increased. However, the calbindin-D28K expression induced by GDNF was specifically blocked by the inhibitor of phosphatidylinositol 3-kinase (PI3K), but the inhibitor of ERK1/2 did not block the calbindin-D28K expression. Furthermore, GDNF administration also caused the nuclear factor κB (NF-κB/p65), to translocate from cytoplasm into the nucleus, and the inhibitor of PI3K effectively blocked the translocation. Immunoprecipitation assay results further demonstrated that it was the p65/p52 complex of NF-κB, rather than the p65/p50 complex that translocated into the neuronal nucleus. The calbindin-D28K expression induced by GDNF was also inhibited when the NF-κB signaling pathway was blocked by Helenalin. These results described a novel mechanism by which the activation of PI3K/Akt→NF-κB (p65/p52) signaling pathway could play a role in the calbindin-D28K expression induced by GDNF.

The role of parvalbumin and calbindin D28k in experimental scrapie

Prion diseases are generally characterized by pronounced neuronal loss. In particular, a subpopulation of inhibitory neurones, characterized by the expression of the calcium-binding protein parvalbumin (PV), is selectively destroyed early in the course of human and experimental prion diseases. By contrast, nerve cells expressing calbindin D28 k (CB), another calcium-binding protein, as well as PV/CB coexpressing Purkinje cells, are well preserved. To evaluate, if PV and CB may directly contribute to neuronal vulnerability or resistance against nerve cell death, respectively, we inoculated PV- and CB-deficient mice, and corresponding controls, with 139A scrapie and compared them with regard to incubation times and histological lesion profiles. While survival times were slightly but significantly diminished in CB-/-, but not PV-/- mice, scrapie lesion profiles did not differ between knockout mice and controls. There was a highly significant and selective loss of isolectin B(4)-decorated perineuronal nets (which specifically demarcate the extracellular matrix surrounding the 'PV-expressing' subpopulation of cortical interneurones) in scrapie inoculated PV+/+, as well as PV-/- mice. Purkinje cell numbers were not different in CB+/+ and CB-/- mice. Our results suggest that PV expression is a surrogate marker for neurones highly vulnerable in prion diseases, but that the death of these neurones is unrelated to PV expression and thus based on a still unknown pathomechanism. Further studies including the inoculation of mice ectopically (over)expressing CB are necessary to determine whether the shortened survival of CB-/- mice is indeed due to a neuroprotective effect of this molecule.