Expression Of Calretinin Research Articles

Calretinin expression in odontogenic cysts and odontogenic tumors and the possible role of calretinin in pathogenesis of ameloblastoma.

Introduction:Histopathological diagnosis of odontogenic cysts and tumors is a task mostly accomplished with hematoxylin and eosin staining. However, the use of additional diagnostic modalities such as immunohistochemistry may be necessary in histologically similar lesions. The reports of studies which have used calretinin as an immunohistochemical marker for ameloblastoma have been conflicting.Aim:The aim of the study was to evaluate the use of calretinin as a specific diagnostic marker for ameloblastoma and observe its expression in odontogenic cysts and other odontogenic tumors.Materials and Methods:Formalin-fixed, paraffin-embedded sections were taken from the archives which included 15 cases each of dentigerous cyst, radicular cyst, odontogenic keratocyst and ameloblastoma five cases of adenomatoid odontogenic tumor and three cases of ameloblastic carcinoma. Immunohistochemistry was done with calretinin antibody.Results:All ameloblastomas were positive for calretinin, whereas no other tumor or cyst showed positivity. Differences in proportion of calretinin expression were statistically significant with P = 0.000.Conclusion:Calretinin can be considered as a specific marker for ameloblastomas.

Expression of Calretinin Among Different Neurochemical Classes of Interneuron in the Superficial Dorsal Horn of the Mouse Spinal Cord

Around 75% of neurons in laminae I-II of the mouse dorsal horn are excitatory interneurons, and these are required for normal pain perception. We have shown that four largely non-overlapping excitatory interneuron populations can be defined by expression of the neuropeptides neurotensin, neurokinin B (NKB), gastrin-releasing peptide (GRP) and substance P. In addition, we recently identified a population of excitatory interneurons in glabrous skin territory that express dynorphin. The calcium-binding protein calretinin is present in many excitatory neurons in this region, but we know little about its relation to these neuropeptide markers. Here we show that calretinin is differentially expressed, being present in the majority of substance P-, GRP- and NKB-expressing cells, but not in the neurotensin or dynorphin cells. Calretinin-positive cells have been implicated in detection of noxious mechanical stimuli, but are not required for tactile allodynia after neuropathic pain. Our findings are therefore consistent with the suggestion that neuropathic allodynia involves the neurotensin and/or dynorphin excitatory interneuron populations. Around a quarter of inhibitory interneurons in lamina I-II contain calretinin, and recent transcriptomic studies suggest that these co-express substance P. We confirm this, by showing that inhibitory Cre-expressing cells in a Tac1Cre knock-in mouse are calretinin-immunoreactive. Interestingly, there is evidence that these cells express low levels of peptidylglycine alpha-amidating monooxygenase, an enzyme required for maturation of neuropeptides. This may explain our previous finding that although the substance P precursor preprotachykinin A can be detected in some inhibitory interneurons, very few inhibitory axonal boutons are immunoreactive for substance P.

Antidepressant but Not Prophylactic Ketamine Administration Alters Calretinin and Calbindin Expression in the Ventral Hippocampus.

Ketamine has been found to have rapid, long-lasting antidepressant effects in treatment-resistant (TR) patients with major depressive disorder (MDD). Recently, we have also shown that ketamine acts as a prophylactic to protect against the development of stress-induced depressive-like behavior in mice, indicating that a preventative treatment against mental illness using ketamine is possible. While there is significant investigation into ketamine’s antidepressant mechanism of action, little is known about ketamine’s underlying prophylactic mechanism. More specifically, whether ketamine’s prophylactic action is molecularly similar to or divergent from its antidepressant action is entirely unknown. Here, we sought to characterize immunohistochemical signatures of cell populations governing ketamine’s antidepressant and prophylactic effects. 129S6/SvEv mice were treated with saline (Sal) or ketamine (K) either before a social defeat (SD) stressor as a prophylactic, or after SD as an antidepressant, then subsequently assessed for depressive-like behavior. Post-fixed brains were processed for doublecortin (DCX), calretinin (CR) and calbindin (CB) expression. The number of DCX+ neurons in the dentate gyrus (DG) of the hippocampus (HPC) was not affected by prophylactic or antidepressant ketamine treatment, while the number of CR+ neurons in the ventral hilus increased with antidepressant ketamine under SD conditions. Moreover, antidepressant, but not prophylactic ketamine administration significantly altered CR and CB expression in the ventral HPC (vHPC). These data show that while antidepressant ketamine treatment mediates some of its effects via adult hippocampal markers, prophylactic ketamine administration does not, at least in 129S6/SvEv mice. These data suggest that long-lasting behavioral effects of prophylactic ketamine are independent of hippocampal DCX, CR and CB expression in stress-susceptible mice.

Changes in the Expression of Calbindin and Calretinin in Interneurons of the Spinal Dorsal Horns Under Conditions of Antiorthostatic Suspension in Mice.

In female C57Bl/6 mice subjected to antiorthostatic suspension of the hind limbs for 30 days, calbindin- and calretinin-containing interneurons of the dorsal horns of the upper thoracic segments of the spinal cord were studied using immunohistochemical methods. In mice of the experimental group, cross-sectional area of calbindin- and calretinin-containing interneurons decreased in laminae I, II, and III and increased in laminae IV and V and in the region of the medial edge of the dorsal horn. After antiorthostatic suspension, expression of calretinin decreased in interneurons of laminae I and II and calbindin expression increased in the interneurons of laminae III, IV, and V. The total number of interneurons in laminae of the spinal cord detected by Nissl staining in the control and experimental groups remained unchanged. After antiorthostatic suspension and in control group, number of interneurons immunoreactive for calbindin and calretinin was maximum in lamina II and minimum in laminae IV and V and in the region of the medial edge of the spinal dorsal horn.

Solid papillary carcinoma with reverse polarity of the breast harbors specific morphologic, immunohistochemical and molecular profile in comparison with other benign or malignant papillary lesions of the breast: a comparative study of 9 additional cases

Solid papillary carcinoma with reverse polarity is a rare breast cancer of favorable prognosis that can be difficult to diagnose. We report here nine additional cases of this tumor, and we describe its morphologic, immunohistochemical and molecular profile in comparison to other types of papillary and micropapillary lesions of the breast that are intraductal papilloma with usual ductal hyperplasia, encapsulated papillary carcinoma, solid papillary carcinoma and invasive micropapillary carcinoma. We studied nine cases of this special papillary tumor and six of each other types mentioned above. We found that solid papillary carcinoma with reverse polarity harbor specific morphologic features as cuboid or tall cells with abundant eosinophilic cytoplasms located at the basal pole giving the impression of reverse nuclear polarity. Nuclei were sometimes grooved. Immunohistochemistry demonstrated the lack of myoepithelial cells, as in encapsulated papillary carcinoma and solid papillary carcinoma, questioning their invasive nature. Seven of nine solid papillary carcinoma with reverse polarity showed a low Ki67 proliferative index (Ki67 <5%). They showed expression of CK5/6 as in intraductal papilloma with usual ductal hyperplasia. They showed expression of calretinin and a low or lack of hormonal receptor (HR) expression that were not observed in other breast tumors studied. By whole-exome analysis, seven of nine solid papillary carcinomas with reverse polarity (78%) harbored a hotspot mutation in IDH2 (R172) that was totally absent in other groups. Six of nine tumors (67%) also harbored PRUNE2 mutation, including the two IDH2 wild-type cases. We also demonstrated for the first time in this breast tumor, immunostaining with a specific antibody IDH1/2 mutant R132/R172 (7/9) that can highlight IDH2 mutation. Moreover, transcriptomic analysis showed that proteoglycan pathway was significantly enriched. Our findings support the fact that solid papillary carcinoma with reverse polarity is a singular breast neoplasm that can be distinguished from other papillary breast tumors.

Vasoactive Intestinal Polypeptide-Immunoreactive Interneurons within Circuits of the Mouse Basolateral Amygdala.

In cortical structures, principal cell activity is tightly regulated by different GABAergic interneurons (INs). Among these INs are vasoactive intestinal polypeptide-expressing (VIP+) INs, which innervate preferentially other INs, providing a structural basis for temporal disinhibition of principal cells. However, relatively little is known about VIP+ INs in the amygdaloid basolateral complex (BLA). In this study, we report that VIP+ INs have a variable density in the distinct subdivisions of the mouse BLA. Based on different anatomical, neurochemical, and electrophysiological criteria, VIP+ INs could be identified as IN-selective INs (IS-INs) and basket cells expressing CB1 cannabinoid receptors. Whole-cell recordings of VIP+ IS-INs revealed three different spiking patterns, none of which was associated with the expression of calretinin. Genetic targeting combined with optogenetics and in vitro recordings enabled us to identify several types of BLA INs innervated by VIP+ INs, including other IS-INs, basket and neurogliaform cells. Moreover, light stimulation of VIP+ basket cell axon terminals, characterized by CB1 sensitivity, evoked IPSPs in ∼20% of principal neurons. Finally, we show that VIP+ INs receive a dense innervation from both GABAergic inputs (although only 10% from other VIP+ INs) and distinct glutamatergic inputs, identified by their expression of different vesicular glutamate transporters.In conclusion, our study provides a wide-range analysis of single-cell properties of VIP+ INs in the mouse BLA and of their intrinsic and extrinsic connectivity. Our results reinforce the evidence that VIP+ INs are structurally and functionally heterogeneous and that this heterogeneity could mediate different roles in amygdala-dependent functions.SIGNIFICANCE STATEMENT We provide the first comprehensive analysis of the distribution of vasoactive intestinal polypeptide-expressing (VIP+) interneurons (INs) across the entire mouse amygdaloid basolateral complex (BLA), as well as of their morphological and physiological properties. VIP+ INs in the neocortex preferentially target other INs to form a disinhibitory network that facilitates principal cell firing. Our study is the first to demonstrate the presence of such a disinhibitory circuitry in the BLA. We observed structural and functional heterogeneity of these INs and characterized their input/output connectivity. We also identified several types of BLA INs that, when inhibited, may provide a temporal window for principal cell firing and facilitate associative plasticity, e.g., in fear learning.

Absence of calretinin protein expression in malignant mesotheliomas from asbestos-exposed NF2+/\u2212 mice and mouse mesothelioma cell lines from various mouse strains

BackgroundCalretinin is the most widespread positive marker for the immunohistochemical identification of malignant mesothelioma (MM) and was proposed to serve as a blood-based biomarker. Functionally, evidence has accumulated that calretinin might be implicated in MM tumorigenesis. We aimed to identify calretinin (CR; Calb2) in murine MM and reactive mesothelial cells in granuloma from asbestos-exposed NF2+/− mice, a line heterozygous for the tumor suppressor merlin (NF2), used as a mouse MM model. Additionally, we sought to ascertain the presence of calretinin in MM cell lines from other mouse strains. We also intended to investigate the role of calretinin in mesotheliomagenesis by comparing the survival of asbestos-exposed NF2+/− and NF2+/-CR−/− mice.MethodsNF2+/− and NF2+/-CR−/− mice, both lines on a C57Bl/6J background, were exposed to asbestos following an established protocol. Tumor histology and asbestos-induced mortality were assessed. MM and granuloma from NF2+/− mice were analyzed with immunohistochemical methods for calretinin expression. Levels of Calb2 mRNA and calretinin expression in tumors and MM cell lines of various mouse strains were determined by RT-qPCR and Western blot analysis, respectively.ResultsNo expression of calretinin at the protein level was detected, neither in MM from NF2+/− mice, NF2+/− MM-derived cell lines nor immortalized mesothelial cells of mouse origin. At the mRNA level we detected Calb2 expression in MM cell lines from different mouse strains. Survival of NF2+/− and NF2+/-CR−/− mice exposed to asbestos showed no significant difference in a log-rank (Kaplan-Meier) comparison.ConclusionsThe concomitant determination of calretinin and mesothelin blood levels has been proposed for early detection of human MM. Mouse MM models based on asbestos exposure are assumed to yield helpful information on the time course of appearance of mesothelin and calretinin in the blood of asbestos-treated mice determining the earliest time point for interventions. However, the observed absence of calretinin in MM from NF2+/− mice and derived cell lines, as well as from MM cells from Balb/c and C3H mice likely precludes the use of calretinin as a biomarker for mouse MM. The results also indicate possible species differences with respect to an involvement of calretinin in the formation of MM.

A Subset of Palisade Endings Only in the Medial and Inferior Rectus Muscle in Monkey Contain Calretinin.

PurposeTo further chemically characterize palisade endings in extraocular muscles in rhesus monkeys.MethodsExtraocular muscles of three rhesus monkeys were studied for expression of the calcium-binding protein calretinin (CR) in palisade endings and multiple endings. The complete innervation was visualized with antibodies against the synaptosomal-associated protein of 25 kDa and combined with immunofluorescence for CR. Six rhesus monkeys received tracer injections of choleratoxin subunit B or wheat germ agglutinin into either the belly or distal myotendinous junction of the medial or inferior rectus muscle to allow retrograde tracing in the C-group of the oculomotor nucleus. Double-immunofluorescence methods were used to study the CR content in retrogradely labeled neurons in the C-group.ResultsA subgroup of palisade and multiple endings was found to express CR, only in the medial and inferior rectus muscle. In contrast, the en plaque endings lacked CR. Accordingly, within the tracer-labeled neurons of the C-group, a subgroup expressed CR.ConclusionsThe study indicates that two different neuron populations targeting nontwitch muscle fibers are present within the C-group for inferior rectus and medial rectus, respectively, one expressing CR, one lacking CR. It is possible that the CR-negative neurons represent the basic population for all extraocular muscles, whereas the CR-positive neurons giving rise to CR-positive palisade endings represent a specialized, perhaps more excitable type of nerve ending in the medial and inferior rectus muscles, being more active in vergence. The malfunction of this CR-positive population of neurons that target nontwitch muscle fibers could play a significant role in strabismus.

Characterization and potential roles of calretinin in rodent spermatozoa

Calretinin has been detected in various excitable cells but the presence and putative roles of such a calcium-binding protein has never been characterized in sperm.Epididymal spermatozoa were collected from C57Bl6 (wild-type, WT) or calretinin knockout (CR−/−) mice and Wistar rats. A specific staining for calretinin was detected by immunofluorescence in the principal piece of the flagellum, both in WT mouse and rat spermatozoa. Western blots confirmed the expression of calretinin in rat and WT spermatozoa as well as its absence in CR−/− mice.No significant difference was observed in the spontaneous acrosome reaction between WT and CR−/− sperm. The addition of the calcium-ionophore A-23187, Thapsigargin or Progesterone to WT or CR−/− incubated spermatozoa induced increases in the acrosome reaction but the stimulatory effects were identical in both genotypes. Motility measurements assessed by computer-assisted sperm analysis indicated that, under basal non-stimulatory conditions, CR-/- sperm exhibited a lower curvilinear velocity and a smaller lateral head movement amplitude, although no difference was observed for the beat cross frequency. After incubation with 25 mM NH4Cl, the curvilinear velocity, the amplitude of the lateral head movement and the hyperactivation were increased, while the beat cross frequency was decreased, in both genotypes.Evaluation of the in vivo fertility potential indicated that the CR−/− litter sizes were clearly reduced compared to the WT litter sizes.Our study describes, for the first time, the expression of calretinin in sperm. These data extend the potential implication of calcium-binding proteins in the sperm calcium-signaling cascade and bring new insights into the understanding of sperm physiology.

Loss of calretinin and parvalbumin positive interneurones in the hippocampal CA1 of aged Alzheimer’s disease mice

Neuronal degeneration associated with Alzheimer’s disease (AD), is linked to impaired calcium homeostasis and to changes in calcium-binding proteins (CBPs). The AD-related modification of neuronal CBPs remains controversial. Here we analysed the presence and expression of calretinin (CR) and parvalbumin (PV) in the hippocampal CA1 neurones of 18 months old 3xTg-AD mice compared to non-Tg animals. We found a layer specific decrease in number of interneurones expressing CR and PV (by 33.7% and 52%, respectively). Expression of PV decreased (by 13.8%) in PV-positive neurones, whereas expression of CR did not change in CR positive cells. The loss of specific subpopulations of Ca2+-binding proteins expressing interneurones (CR and PV) together with the decrease of PV in the surviving cells may be linked to their vulnerability to AD pathology. Specific loss of inhibitory interneurones with age could contribute to overall increase in the network excitability associated with AD.

Calretinin Participates in Regulating Steroidogenesis by PLC-Ca2+-PKC Pathway in Leydig Cells

Calretinin, a Ca2+-binding protein, participates in many cellular events. Our previous studies found the high expression of calretinin in testicular Leydig cells. In this study, (MLTC-1 cells were infected with LV-calb2, R2C cells with LV-siRNA-calb2. The primary mouse Leydig cells were also used to confirm those data from cell lines. Testosterone level was significantly higher in the MLTC-1 cells with over-expressed calretinin than in the control, while progesterone was lower in the R2C cells in which down-regulated calretinin. The expressions of StAR changed in synchrony with hormones. Cytoplasmic Ca2+ level was significantly increased when calretinin was over-expressed. When MLTC-1 cells were infected with LV-calb2 and then stimulated using Clopiazonic, a Ca2+-releasing agent, testosterone was significantly increased. Interestingly, the expression levels of PLC, p-PKCµ (PKD), p-MARCKS and CREB, were significantly increased in the MLTC-1 cells with over-expressed calretinin, while PLC, p-PKD, p-MARCKS, MARCKS and CREB were decreased in the R2C cells with down-regulated calretinin. We also observed the increased expression of calretinin up-regulated testosterone production and the expressions of StAR and PLC in primary mouse Leydig cells. So, calretinin as a Ca2+-binding protein participates in the regulation of steroidogenesis via the PLC-Ca2+-PKC pathway in Leydig cells.

Regulation of calretinin in malignant mesothelioma is mediated by septin 7 binding to the CALB2 promoter

BackgroundThe calcium-binding protein calretinin (gene name: CALB2) is currently considered as the most sensitive and specific marker for the diagnosis of malignant mesothelioma (MM). MM is a very aggressive tumor strongly linked to asbestos exposure and with no existing cure so far. The mechanisms of calretinin regulation, as well as its distinct function in MM are still poorly understood.MethodsWe searched for transcription factors binding to the CALB2 promoter and modulating calretinin expression. For this, DNA-binding assays followed by peptide shotgun-mass spectroscopy analyses were used. CALB2 promoter activity was assessed by dual-luciferase reporter assays. Furthermore, we analyzed the effects of CALB2 promoter-binding proteins by lentiviral-mediated overexpression or down-regulation of identified proteins in MM cells. The modulation of expression of such proteins by butyrate was determined by subsequent Western blot analysis. Immunohistochemical analysis of embryonic mouse lung tissue served to verify the simultaneous co-expression of calretinin and proteins interacting with the CALB2 promoter during early development. Finally, direct interactions of calretinin with target proteins were evidenced by co-immunoprecipitation experiments.ResultsSeptin 7 was identified as a butyrate-dependent transcription factor binding to a CALB2 promoter region containing butyrate-responsive elements (BRE) resulting in decreased calretinin expression. Accordingly, septin 7 overexpression decreased calretinin expression levels in MM cells. The regulation was found to operate bi-directionally, i.e. calretinin overexpression also decreased septin 7 levels. During murine embryonic development calretinin and septin 7 were found to be co-expressed in embryonic mesenchyme and undifferentiated mesothelial cells. In MM cells, calretinin and septin 7 colocalized during cytokinesis in distinct regions of the cleavage furrow and in the midbody region of mitotic cells. Co-immunoprecipitation experiments revealed this co-localization to be the result of a direct interaction between calretinin and septin 7.ConclusionsOur results demonstrate septin 7 not only serving as a “cytoskeletal” protein, but also as a transcription factor repressing calretinin expression. The negative regulation of calretinin by septin 7 and vice versa sheds new light on mechanisms possibly implicated in MM formation and identifies these proteins as transcriptional regulators and putative targets for MM therapy.

Baseline striatal and nigral interneuronal protein levels in two distinct mice strains differ in accordance with their MPTP susceptibility

Epidemiological studies reveal an ethnicity-based bias in prevalence of Parkinson’s disease (PD), deriving from the differences that exist between Caucasians and African or Asian populations. Experimental mice models provide a scope to analyse the cellular mechanisms of differential susceptibility to PD. C57BL/6J mice, for instance, are more susceptible to MPTP-induced Parkinsonism whereas CD-1 mice are resistant. In PD-pathogenesis, interneuronal contribution is also likely, although they comprise only 5–10% of the striatal cells. The interneurons harbour calcium binding proteins, like calretinin (Cal-R) and parvalbumin (PV), which are crucial in Ca2+ homeostasis for preventing calcium-induced excitotoxicity. GAD-67-immunoreactive interneurons are the other prominent set of GABAergic interneurons. In PD, dopamine loss up-regulates GAD-67 expression in striatal projection neurons and other basal ganglia circuit. We studied the possible contribution of interneurons in determining variable susceptibility by assessing the expression of calretinin, PV and GAD-67 in both striatum and substantia nigra pars compacta (SNpc) in two distinct mice strains, i.e. C57BL/6J and CD-1 under normal conditions, using unbiased stereology for quantification of immunoreactive cells and immunoblotting. The vulnerable C57BL/6J had lesser basal parvalbumin expression in both nigra and striatum whereas the calretinin levels were low only in the striatum. GAD-67 expression showed no perceptible differences in the striatum or SNpc of either of the strains. Differential expression of calcium buffering/binding proteins under normal physiological condition proffers a role for interneurons in the differential susceptibility to PD. Thus, even the baseline susceptibility indices i.e. without using the neurotoxin; can provide vital mechanistic insights into PD pathogenesis.

Value of immunocytochemistry in differential diagnosis of gastric adenocarcinoma, reactive mesothelial cells and malignant epithelial mesothelioma in metastatic effusion fluid

Objective: To investigate the diagnostic value of some antibodies in peritoneal fluid of patients with gastric cancer and malignant epithelioid mesothelioma in serous effusion. Methods: One hundred and eighty-two cases of serous effusion were collected at Jilin Cancer Hospital, from July 2012 to July 2016. The expression of GLUT1, CDX2, Villin, calretinin and WT1 was evaluated using SP immunocytochemical technique in peritoneal fluid samples collected from 98 patients with gastric cancer and 74 patients with reactive mesothelial cells. The expression of GLUT1, calretinin and WT1 was also evaluated in serous effusion from 10 patients with mesothelioma. Results: The sensitivity of GLUT1, CDX2 and Villin in adenocarcinoma cells was 91.8%(90/98), 68.4% (67/98) and 88.8%(87/98), respectively. The specificity was 95.9% (71/74), 100.0%(74/74) and 100.0% (74/74), respectively. The sensitivity of calretinin and WT1 for reactive mesothelium was 93.2% (69/74) and 79.7% (59/74), respectively. The specificity was 96.9% (95/98) and 100.0% (98/98), respectively. The sensitivity of GLUT1, calretinin and WT1 for mesothelioma was 9/10, 9/10 and 7/10. The reactivity of GLUT1, CDX2, Villin, calretinin and WT1 showed a significant difference (P<0.01) between adenocarcinoma cells and reactive mesothelium. The reactivity of GLUT1 showed a significant difference (P<0.01) between mesothelioma and reactive mesothelium. Conclusions: The optimal combination is a panel of GLUT1, CDX2, Villin, calretinin and WT1 for differential diagnosis between adenocarcinoma cells and reactive mesothelium in peritoneal fluid of patients with gastric cancer. Whereas GLUT1, calretinin and WT1 is the best for differential diagnosis between reactive mesothelium and mesothelioma in serous effusions.

Oncomodulin Expression Reveals New Insights into the Cellular Organization of the Murine Utricle Striola.

Oncomodulin (OCM, aka β-parvalbumin) is an EF-hand calcium binding protein that is expressed in a restricted set of hair cells in the peristriolar region of the mammalian utricle. In the present study, we determined the topologic distribution of OCM among hair cell phenotypes to advance our understanding of the cellular organization of the striola and the relationship of these phenotypes with characteristics of tissue polarity. The distributions of OCM-positive (OCM+) hair cells were quantified in utricles of mature C57Bl/6 mice. Immunohistochemistry was conducted using antibodies to OCM, calretinin, and β3-tubulin. Fluorophore-conjugated phalloidin was used to label hair cell stereocilia, which provided the basis for determining hair cell counts and morphologic polarizations. We found OCM expression in striolar types I and II hair cells, though the distributions were dissimilar to the native striolar type I and II distributions, favoring type I hair cells. The distribution of OCM immunoreactivity among striolar type I hair cells also reflected nonrandom distribution among type Ic and Id phenotypes (i.e., those receiving calretinin-positive and calretinin-negative calyces, respectively). However, many OCM+ hair cells were found lateral to the striola, and within the epithelial region encompassing OCM+ hair cells, the distributions of OCM+ types Ic and Id hair cells were similar to the native distributions of Ic and Id in this region. Summarily, these data provide a quantitative perspective supporting the existence of different underlying factors driving the topologic expression of OCM in hair cells than those responsible for tissue polarity characteristics associated within the utricular striola, including calretinin expression in afferent calyces.

Expression of calretinin in odontogenic tumors: An observational study

Background and Aim: Calretinin is largely expressed in the central and peripheral nervous system and is also known to be expressed in the odontogenic epithelium during odontogenesis and in certain odontogenic tumors. However, the role of calretinin in the pathogenesis of odontogenic tumors is yet to be confirmed. Thus, the present study is aimed at evaluating the expression and role of calretinin in selected odontogenic tumors. Materials and Methods: The study included six ameloblastoma and one adenomatoid odontogenic tumor, one calcifying epithelial odontogenic tumor and one deciduous tooth germ. Sections were subjected to immunohistochemistry procedure, and staining intensity, pattern, and localization of the immunopositive cells were determined. Results: Results showed that 50% ameloblastomas were immunopositive to calretinin, whereas adenomatoid and calcifying epithelial odontogenic tumor showed mild reactivity. Intensity was higher in the ameloblastomas compared with the other odontogenic tumors. Conclusion: Calretinin appears to be expressing significantly more in ameloblastoma when compared with other odontogenic tumors. On the basis of these results, it is suggested that calretinin might play a possible role in the pathogenesis of ameloblastomas. However, statistics could not be applied due to the lesser sample size and hence we suggest that further studies have to be done along with other proliferative cell cycle and apoptotic markers with larger sample size.

Prdm13 is required for Ebf3+ amacrine cell formation in the retina

Amacrine interneurons play a critical role in the processing of visual signals within the retina. They are highly diverse, representing 30 or more distinct subtypes. Little is known about how amacrine subtypes acquire their unique gene expression and morphological features. We characterized the gene expression pattern of the zinc-finger transcription factor Prdm13 in the mouse. Consistent with a developmental role, Prdm13 was expressed by Ptf1a+ amacrine and horizontal precursors. Over time, Prdm13 expression diverged from the transiently expressed Ptf1a and marked just a subset of amacrine cells in the adult retina. While heterogeneous, we show that most of these Prdm13+ amacrine cells express the transcription factor Ebf3 and the calcium binding protein calretinin. Loss of Prdm13 did not affect the number of amacrine cells formed during development. However, we observed a modest loss of amacrine cells and increased apoptosis that correlated with the onset timing of Ebf3 expression. Adult Prdm13 loss-of-function mice had 25% fewer amacrine cells, altered calretinin expression, and a lack of Ebf3+ amacrines. Forcing Prdm13 expression in retinal progenitor cells did not significantly increase amacrine cell formation, Ebf3 or calretinin expression, and appeared detrimental to the survival of photoreceptors. Our data show that Prdm13 is not required for amacrine fate as a class, but is essential for the formation of Ebf3+ amacrine cell subtypes. Rather than driving subtype identity, Prdm13 may act by restricting competing fate programs to maintain identity and survival.

Differential Effects of Parkinson's Disease on Interneuron Subtypes within the Human Anterior Olfactory Nucleus.

Synucleinopathies (including α-synucleinopathies), which include Parkinson’s disease (PD), manifest themsevles early on (stage 1) in the olfactory system; preferentially in the anterior olfactory nucleus (AON). In particular, the non-motor, early manifestations of PD include hyposmia, which is the partial loss of the sense of smell. The neural basis of hyposmia in PD, however, is poorly understood; but the AON appears to be a key structure in the disease’s progression. We analyzed whether α-synuclein was involved in the differential interneuron vulnerability associated with PD in the retrobulbar, cortical anterior and cortical posterior divisions of the AON. First, we determined the expression of the calcium binding interneuron markers, calretinin, calbindin and parvalbumin, as well as non-calcium binding interneuron marker, somatostatin, in neuronal cell bodies alone (cells/mm2) and in neuronal cell bodies and neurites (% of area fraction) of post-mortem tissue from PD cases and age-matched controls (n = 4 for each) by immunofluorescent confocal microscopy. Results indicated that parvalbumin expression was upregulated in neuronal cell bodies throughout the anterior olfactory nucleus of PD cases compared with controls. Furthermore, there was increased calbindin, calretinin and parvalbumin expression in the cell bodies and neurites of neurons in the retrobulbar division and also increased parvalbumin expression in the neurites of neurons in the cortical division; calretinin expression was also increased in neuronal cell bodies and neurites in the cortical posterior division. Second, we analyzed the co-localization of the above markers with α-synuclein, with results indicating that α-synuclein co-localized with the calcium-binding proteins, but only partially with somatostatin. Taken together, these results indicate differential expression levels among different neural markers in the divisions of the AON in PD cases and point to several possibilities, among them: possible neuroprotective mechanisms of calcium-binding proteins against α-synuclein; and the differential involvement of somatostatin in α-synuclein-positive cell bodies and neurites.

Individual variability in the structural properties of neurons in the human inferior olive.

The inferior olive (IO) is the sole source of the climbing fibers innervating the cerebellar cortex. We have previously shown both individual differences in the size and folding pattern of the principal nucleus (IOpr) in humans as well as in the expression of different proteins in IOpr neurons. This high degree of variability was not present in chimpanzee samples. The neurochemical differences might reflect static differences among individuals, but might also reflect age-related processes resulting in alterations of protein synthesis. Several observations support the latter idea. First, accumulation of lipofuscin, the "age pigment" is well documented in IOpr neurons. Second, there are silver- and abnormal tau-immunostained intraneuronal granules in IOpr neurons (Ikeda et al. Neurosci Lett 258:113-116, 1998). Finally, Olszewski and Baxter (Cytoarchitecture of the human brain stem, Second edn. Karger, Basel, 1954) observed an apparent loss of IOpr neurons in older individuals. We have further investigated the possibility of age-related changes in IOpr neurons using silver- and immunostained sections. We found silver-labeled intraneuronal granules in neurons of the IOpr in all human cases studied (n = 17, ages 25-71). We did not, however, confirm immunostaining with antibodies to abnormal tau. There was individual variability in the density of neurons as well as in the expression of the calcium-binding protein calretinin. In the chimpanzee, there were neither silver-stained intraneuronal granules nor irregularities in immunostaining. Overall, the data support the hypothesis that in some, but not all, humans there are functional changes in IOpr neurons and ultimately cell death. Neurochemical changes of IOpr neurons may contribute to age-related changes in motor and cognitive skills mediated by the cerebellum.

Non-canonical heterogeneous cellular distribution and co-localization of CaMKII\u03b1 and CaMKII\u03b2 in the spinal superficial dorsal horn

Ca2+/calmodulin-dependent protein kinase II (CaMKII) is a key enzyme in long-term plasticity in many neurons, including in the nociceptive circuitry of the spinal dorsal horn. However, although the role of CaMKII heterooligomers in neuronal plasticity is isoform-dependent, the distribution and co-localization of CaMKII isoforms in the dorsal horn have not been comprehensively investigated. Here, quantitative immunofluorescence analysis was used to examine the distribution of the two major neuronal CaMKII isoforms, α and β, in laminae I–III of the rat dorsal horn, with reference to inhibitory interneurons and neuronal populations defined by expression of parvalbumin, calretinin, and calbindin D28k. Unexpectedly, all or nearly all inhibitory and excitatory neurons showed both CaMKIIα and CaMKIIβ immunoreactivity, although at highly variable levels. Lamina III neurons showed less CaMKIIα immunoreactivity than laminae I–II neurons. Whereas CaMKIIα immunoreactivity was found at nearly similar levels in inhibitory and excitatory neurons, CaMKIIβ generally showed considerably lower immunoreactivity in inhibitory neurons. Distinct populations of inhibitory calretinin neurons and excitatory parvalbumin neurons exhibited high CaMKIIα-to-CaMKIIβ immunoreactivity ratios. CaMKIIα and CaMKIIβ immunoreactivity showed positive correlation at GluA2+ puncta in pepsin-treated tissue. These results suggest that, unlike the forebrain, the dorsal horn is characterized by similar expression of CaMKIIα in excitatory and inhibitory neurons, whereas CaMKIIβ is less expressed in inhibitory neurons. Moreover, CaMKII isoform expression varies considerably within and between neuronal populations defined by laminar location, calcium-binding protein expression, and transmitter phenotype, suggesting differences in CaMKII function both between and within neuronal populations in the superficial dorsal horn.