Differential expression of human γ-tubulin isotypes during neuronal development and oxidative stress points to a γ-tubulin-2 prosurvival function.

γ-Tubulins are highly conserved members of the tubulin superfamily essential for microtubule nucleation. Humans possess 2 γ-tubulin genes. It is thought that γ-tubulin-1 represents a ubiquitous isotype, whereas γ-tubulin-2 is found predominantly in the brain, where it may be endowed with divergent functions beyond microtubule nucleation. The molecular basis of the purported functional differences between γ-tubulins is unknown. We report discrimination of human γ-tubulins according to their electrophoretic and immunochemical properties. In vitro mutagenesis revealed that the differences in electrophoretic mobility originate in the C-terminal regions of the γ-tubulins. Using epitope mapping, we discovered mouse monoclonal antibodies that can discriminate between human γ-tubulin isotypes. Real time quantitative RT-PCR and 2-dimensional-PAGE showed that γ-tubulin-1 is the dominant isotype in fetal neurons. Although γ-tubulin-2 accumulates in the adult brain, γ-tubulin-1 remains the major isotype in various brain regions. Localization of γ-tubulin-1 in mature neurons was confirmed by immunohistochemistry and immunofluorescence microscopy on clinical samples and tissue microarrays. Differentiation of SH-SY5Y human neuroblastoma cells by all-trans retinoic acid, or oxidative stress induced by mitochondrial inhibitors, resulted in upregulation of γ-tubulin-2, whereas the expression of γ-tubulin-1 was unchanged. Fractionation experiments and immunoelectron microscopy revealed an association of γ-tubulins with mitochondrial membranes. These data indicate that in the face of predominant γ-tubulin-1 expression, the accumulation of γ-tubulin-2 in mature neurons and neuroblastoma cells during oxidative stress may denote a prosurvival role of γ-tubulin-2 in neurons.-Dráberová, E., Sulimenko, V., Vinopal, S., Sulimenko, T., Sládková, V., D'Agostino, L., Sobol, M., Hozák, P., Kren, L., Katsetos, C. D., Dráber, P. Differential expression of human γ-tubulin isotypes during neuronal development and oxidative stress points to γ-tubulin-2 prosurvival function.

Malignant glioma with primitive neuroectodermal tumor-like component (MG-PNET): novel microarray findings in a pediatric patient.

Central nervous system (CNS) tumors exhibiting dual features of malignant glioma (MG) and primitive neuroectodermal tumor (PNET) are rare and diagnostically challenging. Previous studies have shown that MG-PNET carry MYCN or MYC gene amplifications within the PNET component concomitant with glioma-associated alterations, most commonly 10q loss, in both components [9]. Here we confirm and extend the profile of molecular genetic findings in a MG-PNET involving the left frontal lobe of a 12-year-old male. Histologically, the PNET-like component showed morphological features akin to anaplastic medulloblastoma highlighted by widespread immunoreactivity for ßIII-tubulin (TUBB3) and nonphosphorylated neurofilament protein, and to a lesser degree, Neu-N, synaptophysin, and CD99, whereas the gliomatous component was demarcated by glial fibrillary acidic protein (GFAP) labeling. Immunohistochemical labeling with an anti-H3K27M mutant-specific antibody was not detectable in either gliomatous and/or PNET-like areas. Interphase fluorescent in situ hybridization (FISH) study on touch preparations from frozen tumor and formaldehyde-fixed, paraffin-embedded histological sections showed amplification of MYC in both PNET-like and gliomatous areas. Single nucleotide polymorphism (SNP) microarray analysis revealed that the tumor carried gains of multiple chromosomes and chromosome arms, losses of multiple chromosomes and chromosome arms, gains of multiple chromosomal segments (not limited to amplification of chromosomal segments 4q12 including PDGFRA, and 8q24.21 including MYC), and a hitherto unreported chromothripsis-like abnormality on chromosome 8. No mutations were identified for IDH1, IDH2, or BRAF genes by sequence analysis. The molecular genetic findings support the presence of a CNS-PNET as an integral part of the tumor coupled with overlapping genetic alterations found in both adult and pediatric high-grade gliomas/glioblastoma. Collectively, microarray data point to a complex underpinning of genetic alterations associated with the MG-PNET tumor phenotype.
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ENhancinG vAGinal dElivery in Greece through educational and behavioral interventions among maternity care providers regarding labor management: the ENGAGE stepped-wedge randomized prospective trial protocol.

BACKGROUND: There is an emerging need to systematically investigate the causes for the increased cesarean section rates in Greece and undertake interventions so as to substantially reduce its rates. To this end, the ability of the participating Greek obstetricians to follow evidence-based guidelines and respond to other educational and behavioral interventions while managing labor will be explored, along with barriers and enablers. Herein discussed is the protocol of a stepped-wedge designed intervention trial in Greek maternity units with the aforementioned goals in mind, named ENGAGE (ENhancinG vAGinal dElivery in Greece). METHODS: Twenty-two selected maternity units in Greece will participate in a multicenter stepped-wedge randomized prospective trial involving 20,000 to 25,000 births, with two of them entering the intervention period of the study each month (stepped randomization). The maternity care units entering the study will apply the suggested interventions for a period of 8-18 months depending on the time they enter the intervention stage of the study. There will also be an initial phase of the study lasting from 8 to 18 months including observation and recording of the routine practice (cesarean section, vaginal birth, and maternal and perinatal morbidity and mortality) in the participating units. The second phase, the intervention period, will include such interventions as the application of the HSOG (the Hellenic Society of Obstetrics and Gynecology) Guidelines on labor management, training on the correct interpretation of cardiotocography, and dealing with emergencies in vaginal deliveries, while the steering committee members will be available to discuss and implement organizational and behavioral changes, answer questions, clarify relevant issues, and provide practical instructions to the participating healthcare professionals during regular visits or video conferences. Furthermore, during the study, the results will be available for the participating units in order for them to monitor their own performance while also receiving feedback regarding their rates. Τhe final 2-month phase of the study will be devoted to completing follow-up questionnaires with data concerning maternal and neonatal morbidities that occurred after the completion of the intervention period. The total duration of the study is estimated at 28 months. The primary outcome assessed will be the cesarean section rate change and the secondary outcomes will be maternal and neonatal morbidity and mortality. DISCUSSION: The study is expected to yield new information on the effects, advantages, possibilities, and challenges of consistent clinical engagement and implementation of behavioral, educational, and organizational interventions described in detail in the protocol on cesarean section practice in Greece. The results may lead to new insights into means of improving the quality of maternal and neonatal care, particularly since this represents a shared effort to reduce the high cesarean section rates in Greece and, moreover, points the way to their reduction in other countries. TRIAL REGISTRATION: NCT04504500 (ClinicalTrials.gov). The trial was prospectively registered. Ethics Reference No: 320/23.6.2020, Bioethics and Conduct Committee, School of Medicine, National and Kapodistrian University of Athens, Athens, Greece.

Nuclear γ-tubulin associates with nucleoli and interacts with tumor suppressor protein C53.

γ-Tubulin is assumed to be a typical cytosolic protein necessary for nucleation of microtubules from microtubule organizing centers. Using immunolocalization and cell fractionation techniques in combination with siRNAi and expression of FLAG-tagged constructs, we have obtained evidence that γ-tubulin is also present in nucleoli of mammalian interphase cells of diverse cellular origins. Immunoelectron microscopy has revealed γ-tubulin localization outside fibrillar centers where transcription of ribosomal DNA takes place. γ-Tubulin was associated with nucleolar remnants after nuclear envelope breakdown and could be translocated to nucleoli during mitosis. Pretreatment of cells with leptomycin B did not affect the distribution of nuclear γ-tubulin, making it unlikely that rapid active transport via nuclear pores participates in the transport of γ-tubulin into the nucleus. This finding was confirmed by heterokaryon assay and time-lapse imaging of photoconvertible protein Dendra2 tagged to γ-tubulin. Immunoprecipitation from nuclear extracts combined with mass spectrometry revealed an association of γ-tubulin with tumor suppressor protein C53 located at multiple subcellular compartments including nucleoli. The notion of an interaction between γ-tubulin and C53 was corroborated by pull-down and co-immunoprecipitation experiments. Overexpression of γ-tubulin antagonized the inhibitory effect of C53 on DNA damage G(2) /M checkpoint activation. The combined results indicate that aside from its known role in microtubule nucleation, γ-tubulin may also have nuclear-specific function(s).

Improving tissue characterization, differentiation and diagnosis in gynecology with the narrow-band imaging technique: A systematic review.

Narrow-band imaging (NBI), an on-demand, real-time endoscopic imaging technique, was developed to enhance visualization of the mucosal vascular network and surface texture. The present article provides a systematic review of studies that assessed the use of NBI in gynecological endoscopy. The following electronic databases were searched: PubMed (1950-2020), Google Scholar (2004-2020) and Cochrane Library (2010-2020). In the initial search, 3,836 entries were identified, of which 31 were finally included in the systematic review. Of the selected studies, 10 (32%) were case reports, 19 (61.2%) were prospective studies and 2 (6.4%) were randomized controlled trials with control groups. The selected studies reported on the use of NBI in hysteroscopy, laparoscopy and colposcopy. It was revealed that NBI utilization in hysteroscopy increased the accuracy, sensitivity and specificity in detecting malignant and premalignant lesions. NBI improved the specificity and sensitivity in the detection of endometriotic lesions and cervical lesions. Conventional white light endoscopy in gynecology may be significantly improved by the use of NBI. Further studies with larger cohorts and improved design are required to achieve more reliable results. It is of special interest that utilization of this method requires apparatus which is expensive; concerns are the long training and experience of staff required and the long learning curve.

O-GlcNAc transferase regulates glioblastoma acetate metabolism via regulation of CDK5-dependent ACSS2 phosphorylation.

Glioblastomas (GBMs) preferentially generate acetyl-CoA from acetate as a fuel source to promote tumor growth. O-GlcNAcylation has been shown to be elevated by increasing O-GlcNAc transferase (OGT) in many cancers and reduced O-GlcNAcylation can block cancer growth. Here, we identify a novel mechanism whereby OGT regulates acetate-dependent acetyl-CoA and lipid production by regulating phosphorylation of acetyl-CoA synthetase 2 (ACSS2) by cyclin-dependent kinase 5 (CDK5). OGT is required and sufficient for GBM cell growth and regulates acetate conversion to acetyl-CoA and lipids. Elevating O-GlcNAcylation in GBM cells increases phosphorylation of ACSS2 on Ser-267 in a CDK5-dependent manner. Importantly, we show that ACSS2 Ser-267 phosphorylation regulates its stability by reducing polyubiquitination and degradation. ACSS2 Ser-267 is critical for OGT-mediated GBM growth as overexpression of ACSS2 Ser-267 phospho-mimetic rescues growth in vitro and in vivo. Importantly, we show that pharmacologically targeting OGT and CDK5 reduces GBM growth ex vivo. Thus, the OGT/CDK5/ACSS2 pathway may be a way to target altered metabolic dependencies in brain tumors.

Human breast tumor cells express IL-10 and IL-12p40 transcripts and proteins, but do not produce IL-12p70.

IL-10 transcripts were expressed in 14/15 primary breast adenocarcinomas and in 5/8 established breast tumor lines. Immunohistochemistry and immunoprecipitation from lysates and supernatants revealed that established breast tumor lines produced IL-10 protein. Immunohistochemistry revealed that IL-10 is localized to tumor cells of primary breast adenocarcinomas and to occasional infiltrating MNC. Established breast tumor cell lines expressed IL-12p40 transcripts (6/8) and protein (4/7) and IL-12p35 transcripts (6/7). Using two sandwich ELISAs, specific, respectively, for IL-12p40 and IL-12p70 proteins, we demonstrated that established breast tumor cell lines produce IL-12p40 monomer/homodimer, but not IL-12p70. Positive staining for IL-12p70 in primary breast adenocarcinomas was found only in MNC infiltrating the tumor while tumor cells were negative. IL-12p40 homodimer/monomer inhibit as antagonists IL-12 or IL-23, although they may also act as agonists and positive regulators. Also, primary breast adenocarcinomas (15/15) and established breast tumor cell lines (6/8) expressed TGF-ß1 transcripts. IL-10, IL-12p40 and TGF-ß1 may inhibit substantially the anti-tumor immune response.

Differential expression and cellular distribution of gamma-tubulin and betaIII-tubulin in medulloblastomas and human medulloblastoma cell lines.

In previous studies, we have shown overexpression and ectopic subcellular distribution of gamma-tubulin and betaIII-tubulin in human glioblastomas and glioblastoma cell lines (Katsetos et al., 2006, J Neuropathol Exp Neurol 65:455-467; Katsetos et al., 2007, Neurochem Res 32:1387-1398). Here we determined the expression of gamma-tubulin in surgically excised medulloblastomas (n = 20) and in the human medulloblastoma cell lines D283 Med and DAOY. In clinical tissue samples, the immunohistochemical distribution of gamma-tubulin labeling was pervasive and inversely related to neuritogenesis. Overexpression of gamma-tubulin was widespread in poorly differentiated, proliferating tumor cells but was significantly diminished in quiescent differentiating tumor cells undergoing neuritogenesis, highlighted by betaIII-tubulin immunolabeling. By quantitative real-time PCR, gamma-tubulin transcripts for TUBG1, TUBG2, and TUBB3 genes were detected in both cell lines but expression was less prominent when compared with the human glioblastoma cell lines. Immunoblotting revealed comparable amounts of gamma-tubulin and betaIII-tubulin in different phases of cell cycle; however, a larger amount of gamma-tubulin was detected in D283 Med when compared with DAOY cells. Interphase D283 Med cells exhibited predominantly diffuse cytoplasmic gamma-tubulin localization, in addition to the expected centrosome-associated distribution. Robust betaIII-tubulin immunoreactivity was detected in mitotic spindles of DAOY cells. Our data indicate that overexpression of gamma-tubulin may be linked to phenotypic dedifferentiation (anaplasia) and tumor progression in medulloblastomas and may potentially serve as a promising tumor marker.

Tubulin targets in the pathobiology and therapy of glioblastoma multiforme. II. gamma-Tubulin.

Glioblastoma multiforme (GBM) is the most common and deadliest form of primary brain cancer in adults. Despite advances in molecular biology and genetics of cancer there is no currently available treatment for these tumors. Aberrant patterns of gamma-tubulin expression and compartmentalization in GBM have been reported lending credence to the assertion that these changes might underlie perturbations in microtubule nucleation and mitosis associated with glioma tumorigenesis and tumor progression. This minireview focuses on the role of gamma-tubulin in the pathobiology of GBM in the light of emerging concepts concerning the function of gamma-tubulin and its potential role in tumorigenesis putting forward the concept that gamma-tubulin might serve as a novel marker of anaplastic change in gliomas.

Tubulin targets in the pathobiology and therapy of glioblastoma multiforme. I. Class III beta-tubulin.

Glioblastoma multiforme (GBM) is the most common and deadliest form of primary brain cancer in adults. Despite advances in molecular biology and genetics of gliomas currently there is no effective treatment or promising molecularly targeted experimental therapeutic strategies for these tumors. In previous studies we have shown aberrant overexpression of the class III beta-tubulin isotype (betaIII-tubulin) in GBM and have proposed that this change may reflect perturbations in microtubule dynamics associated with glioma tumorigenesis, tumor progression and malignant transformation into GBM. This minireview focuses on microtubules and tubulin as emerging targets in potential therapy of GBM using a new class of betaIII-tubulin-targeted drugs in the light of recent developments concerning the function and potential role of this isotype in clinically aggressive tumor behavior, cancer stem cells, tumor hypoxia and chemoresistance to tubulin binding agents, principally taxanes.

Expression of γ-tubulin in non-small cell lung cancer and effect on patient survival.

INTRODUCTION: It has been reported that overexpression and altered compartmentalization of γ-tubulin may contribute to tumorigenesis and tumor aggressiveness in a variety of human malignancies. We have shown that γ-tubulin expression and cellular distribution pattern is also altered in non-small cell lung cancer (NSCLC) (Histol. Histopathol. 2012; 27: 1183-1194). In the present study we examined the relationship between γ-tubulin expression and patient overall survival (OS). MATERIAL AND METHODS: Immunohistochemistry was performed, with well-characterized anti-γ-tubulin antibodies, on 109 formalin-fixed, paraffin-embedded NSCLC specimens (p-TNM stage I-III). γ-Tubulin labeling indexes (LIs) were determined, and the association of γ-tubulin expression with clinicopathological parameters was evaluated. To analyze OS rates according to γ-tubulin LIs, patients were categorized into three groups: those with low (0-30%), intermediate (31-69%) or high (70-100%) γ-tubulin LI. Association of clinicopathological parameters and γ-tubulin with survival were examined using univariate and multivariate Cox regression analysis. RESULTS: No statistically significant association was seen between γ-tubulin overexpression and histological type, tumor differentiation, p-TNM stage and adenocarcinoma subtyping. Longer survival was observed in the high γ-tubulin LI group of patients with p-TNM stages II+III when compared to intermediate or low γ-tubulin LI groups, but the difference was not statistically significant (p=0.066). On the other hand, when combined low and intermediate γ-tubulin LI groups (p-TNM stages II+III) where compared to high γ-tubulin LI group, statistically significant longer survival was observed in high γ-tubulin group (p=0.021). CONCLUSION: Our findings suggest that level of γ-tubulin expression may have an impact on patient survival at more advanced NSCLC stages.

Class III beta-tubulin is constitutively coexpressed with glial fibrillary acidic protein and nestin in midgestational human fetal astrocytes: implications for phenotypic identity.

Class III beta-tubulin isotype (betaIII-tubulin) is widely regarded as a neuronal marker in developmental neurobiology and stem cell research. To test the specificity of this marker protein, we determined its expression and distribution in primary cultures of glial fibrillary acidic protein (GFAP)-expressing astrocytes isolated from the cerebral hemispheres of 2 human fetuses at 18 to 20 weeks of gestation. Cells were maintained as monolayer cultures for 1 to 21 days without differentiation induction. By immunofluorescence microscopy, coexpression of betaIII-tubulin and GFAP was detected in cells at all time points but in spatially distinct patterns. The numbers of GFAP+ cells gradually decreased from Days 1 to 21 in vitro, whereas betaIII-tubulin immunoreactivity was present in 100% of cells at all time points. beta-III-tubulin mRNA and protein expression were demonstrated in cultured cells by reverse-transcriptase-polymerase chain reaction and immunoblotting, respectively. Glial fibrillary acidic protein+/beta-III-tubulin-positive cells coexpressed nestin and vimentin but lacked neurofilament proteins, CD133, and glutamate-aspartate transporter. Weak cytoplasmic staining was detected with antibodies against microtubule-associated protein 2 isoforms. Confocal microscopy, performed on autopsy brain samples of human fetuses at 16 to 20 gestational weeks, revealed widespread colocalization of GFAP and betaIII-tubulin in cells of the ventricular/subventricular zones and the cortical plate. Our results indicate that in the midgestational human brain, betaIII-tubulin is not neuron specific because it is constitutively expressed in GFAP+/nestin+ presumptive fetal astrocytes.

[Neuroprotection in perinatal hypoxic-ischemic encephalopathy. Effective treatment and future perspectives]. / Neuroprotección en la encefalopatía hipóxico isquémica perinatal. Tratamientos con eficacia clinica demostrada y perspectivas futuras.

The aim of this paper is to review the results of recent clinical studies of some therapies that have demonstrated a neuroprotective effect in perinatal hypoxic-ischemic encephalopathy (HIE) and to present the future perspectives of other clinical and basic research investigations. THERAPIES WITH DEMONSTRATED CLINICAL EFFICACY: ALLOPURINOL: It blocks the production of free radicals following hypoxia-ischemia. In a recent study, infants with hypoplastic left heart syndrome treated with allopurinol, but not those with other congenital cardiopathies, had significantly less number of complications than controls, including death, seizures, coma or cardiac events. OPIOIDS: In another recent study, newborns with HIE treated with morphine or phentanyl, had less severe brain damage on MRI and a better neurological outcome. HYPOTHERMIA: Both local (head cooling) or systemic (whole body) hypothermia have a neuroprotective effect in selected newborns with HIE. FUTURE PERSPECTIVES: ANTIEPILEPTIC DRUGS: They have multiple mechanisms of action that can block the biochemical cascade of neuronal damage in HIE. OTHER THERAPEUTIC MODALITIES: Among them the following should be emphasized: combined neuroprotective treatments, growth factors, genetic therapies, stem cell transplant, and neuroprotective immunization. In conclusion, a better knowledge of the molecular mechanisms of HIE pathogenesis and better clinical studies of neuroprotective therapies will open new possibilities aplicable to clinical practice. These advances will undoubtedly improve the prognosis of newborns with HIE.

Novel mutations involving ßI-, ßIIA-, or ßIVB-tubulin isotypes with functional resemblance to ßIII-tubulin in breast cancer.

Tubulin is the target for very widely used anti-tumor drugs, including Vinca alkaloids, taxanes, and epothilones, which are an important component of chemotherapy in breast cancer and other malignancies. Paclitaxel and other tubulin-targeting drugs bind to the ß subunit of tubulin, which is a heterodimer of α and ß subunits. ß-Tubulin exists in the form of multiple isotypes, which are differentially expressed in normal and neoplastic cells and differ in their ability to bind to drugs. Among them, the ßIII isotype is overexpressed in many aggressive and metastatic cancers and may serve as a prognostic marker in certain types of cancer. The underpinning mechanisms accounting for the overexpression of this isotype in cancer cells are unclear. To better understand the role of ß-tubulin isotypes in cancer, we analyzed over 1000 clones from 90 breast cancer patients, sequencing their ß-tubulin isotypes, in search of novel mutations. We have elucidated two putative emerging molecular subgroups of invasive breast cancer, each of which involve mutations in the ßI-, ßIIA-, or ßIVB isotypes of tubulin that increase their structural, and possibly functional, resemblance to the ßIII isotype. A unifying feature of the first of the two subgroups is the mutation of the highly reactive C239 residue of ßI- or ßIVB-tubulin to L239, R239, Y239, or P239, culminating in probable conversion of these isotypes from ROS-sensitive to ROS-resistant species. In the second subgroup, ßI, ßIIA, and ßIVB have up to seven mutations to the corresponding residues in ßIII-tubulin. Given that ßIII-tubulin has emerged as a pro-survival factor, overexpression of this isotype may confer survival advantages to certain cancer cell types. In this mini-review, we bring attention to a novel mechanism by which cancer cells may undergo adaptive mutational changes involving alternate ß-tubulin isotypes to make them acquire some of the pro-survival properties of ßIII-tubulin. These "hybrid" tubulins, combining the sequences and/or properties of two wild-type tubulins (ßIII and either ßI, ßIIA, or ßIVB), are novel isotypes expressed solely in cancer cells and may contribute to the molecular understanding and stratification of invasive breast cancer and provide novel molecular targets for rational drug development.

Altered cellular distribution and subcellular sorting of gamma-tubulin in diffuse astrocytic gliomas and human glioblastoma cell lines.

Centrosome amplification is a pivotal mechanism underlying tumorigenesis but its role in gliomas is underinvestigated. The present study specifically examines the expression and distribution of the centrosome-associated cytoskeletal protein gamma-tubulin in 56 primary diffuse astrocytic gliomas (grades II-IV) and in 4 human glioblastoma cell lines (U87MG, U118MG, U138MG, and T98G). Monoclonal anti-peptide antibodies recognizing epitopes in C-terminal or N-terminal domains of the gamma-tubulin molecule were used in immunohistochemical, immunofluorescence, and immunoblotting studies. In tumors in adults (n = 46), varying degrees of localization were detected in all tumor grades, but immunoreactivity was significantly increased in high-grade anaplastic astrocytomas and glioblastomas multiforme as compared to low-grade diffuse astrocytomas (p = 0.0001). A similar trend was noted in diffuse gliomas in children but the sample of cases was too small as to be statistically meaningful. Two overlapping patterns of ectopic cellular localization were identified in both primary tumors and glioblastoma cell lines: A punctate pattern, in which gamma-tubulin was partially co-distributed with pericentrin in the pericentriolar region, and a diffuse pattern, independent of pericentrin staining, denoting a soluble pool of gamma-tubulin. Cellular gamma-tubulin was detected in both soluble and insoluble (nocodazole-resistant) fractions of glioblastoma cells. Divergent localizations of gamma-tubulin and pericentrin suggest a differential distribution of these 2 centrosome-associated proteins in glioblastoma cell lines. Our results indicate that overexpression and ectopic cellular distribution of gamma-tubulin in astrocytic gliomas may be significant in the context of centrosome protein amplification and may be linked to tumor progression and anaplastic potential.

Anomalous inhibitory circuits in cortical tubers of human tuberous sclerosis complex associated with refractory epilepsy: aberrant expression of parvalbumin and calbindin-D28k in dysplastic cortex.

Damage or loss of inhibitory cortical gamma-aminobutyric acid (GABA)ergic interneurons is associated with impaired inhibitory control of neocortical pyramidal cells, leading to hyperexcitability and epileptogenesis. The calcium binding proteins parvalbumin and calbindin-D(28k) are expressed in subpopulations of GABAergic local circuit neurons in the neocortex and can serve as neuronotypic markers. Parvalbumin and calbindin-D(28k) facilitate the neuron's ability to sustain firing and provide neuroprotection. The goal of this study was to assess the hitherto unknown status of inhibitory interneurons in cortical tubers of human tuberous sclerosis complex. Surgically excised cortical tubers from three patients with tuberous sclerosis complex were evaluated immunohistochemically with antibodies to parvalbumin and calbindin-D(28k). Cortical specimens from young patients with intractable seizures, including microdysgenesis (n = 3), postischemic cortical scarring (n = 1), porencephaly (n = 1), postictal gliosis (n = 3), and low-grade neuronal or glial tumors (n = 5), were also examined for comparison. In cortical tubers, calcium binding protein immunoreactivities (calbindin-D(28k) > parvalbumin) were present in medium- or large-size dysplastic neurons, whereas giant or ballooned cells were parvalbumin or calbindin-D(28k) negative. In microdysgenesis, a nearly normal number of parvalbumin-positive neurons and a decreased number of calbindin-D(28k)-positive neurons were present. In peritumoral but more so in gliotic cortex, a coordinate decrease of parvalbumin and calbindin-D(28k) immunoreactivities was present. Our findings indicate that the expression of parvalbumin or calbindin-D(28k) by subpopulations of dysplastic neurons in cortical tubers is aberrant and denotes dysfunctional inhibitory circuits inept for excitoprotection.