Ubiquitin-positive, tau- and alpha-synuclein-negative inclusions are hallmarks of frontotemporal lobar degeneration with ubiquitin-positive inclusions and amyotrophic lateral sclerosis. Although the identity of the ubiquitinated protein specific to either disorder was unknown, we showed that TDP-43 is the major disease protein in both disorders. Pathologic TDP-43 was hyper-phosphorylated, ubiquitinated, and cleaved to generate C-terminal fragments and was recovered only from affected central nervous system regions, including hippocampus, neocortex, and spinal cord. TDP-43 represents the common pathologic substrate linking these neurodegenerative disorders.

No abstract

5-Methylcytosine (5mC) in genomic DNA has important epigenetic functions in embryonic development and tumor biology. 5-Hydroxymethylcytosine (5hmC) is generated from 5mC by the action of the TET (Ten-Eleven-Translocation) enzymes and may be an intermediate to further oxidation and finally demethylation of 5mC. We have used immunohistochemistry (IHC) and isotope-based liquid chromatography mass spectrometry (LC-MS) to investigate the presence and distribution of 5hmC in human brain and brain tumors. In the normal adult brain, IHC identified 61.5% 5hmC positive cells in the cortex and 32.4% 5hmC in white matter (WM) areas. In tumors, positive staining of cells ranged from 1.1% in glioblastomas (GBMs) (WHO Grade IV) to 8.9% in Grade I gliomas (pilocytic astrocytomas). In the normal adult human brain, LC-MS also showed highest values in cortical areas (1.17% 5hmC/dG [deoxyguanosine]), in the cerebral WM we measured around 0.70% 5hmC/dG. 5hmC levels were related to tumor differentiation, ranging from lowest values of 0.078% 5hmC/dG in GBMs (WHO Grade IV) to 0.24% 5hmC/dG in WHO Grade II diffuse astrocytomas. 5hmC measurements were unrelated to 5mC values. We find that the number of 5hmC positive cells and the amount of 5hmC/dG in the genome that has been proposed to be related to pluripotency and lineage commitment in embryonic stem cells is also associated with brain tumor differentiation and anaplasia.Epigenetics, the study of mechanisms that control gene expression (in a potentially heritable way), may be the most rapidly expanding field in tumor biology. On a molecular level, (i) DNA methylation, i.e., covalent modification of cytosine bases resulting in 5-methylcytosine (5mC), (ii) histone modifications and (iii) nucleosome positioning are regarded as the driving epigenetic mechanisms. They are fundamental to the regulation of many cellular processes, including gene and micro RNA expression, DNA-protein interactions, suppression of transposable element mobility, cellular differentiation, embryogenesis, X-chromosome inactivation and genomic imprinting.In tumor biology, DNA methylation is the best-studied epigenetic change. Epigenetic silencing of O 6 -methylguanine DNA-methyltransferase (MGMT) 1 has been described as a strong predictive factor of treatment response to chemotherapy with alkylating agents of glioblastoma (GBM) and anaplastic astrocytoma (AA). 2 Methylation of CpG islands in the MGMT promoter with ensuing repression of MGMT transcriptional activity is generally viewed as the cause for this correlation. 3 Oxidation of 5mC leading to 5-hydroxymethylcytosine (5hmC) has been identified as a new epigenetic phenomenon in mouse Purkinje cells. 4 Three possible modes of action of 5hmC were discussed. (i) It might influence chromatin structure and local transcriptional activity by recruiting selective 5hmC-binding proteins or excluding 5mC-binding proteins.(ii) Conversion of 5mC to 5hmC might facilitate passive DNA demethylation by excluding the maintenance DNMT1, which recognizes 5hmC poorly. (iii) 5hmC may...

Mitotic activity is one of the most reliable prognostic factors in meningiomas. The identification of mitotic figures (MFs) and the areas of highest mitotic activity in H&E-stained slides is a tedious and subjective task. Therefore, we compared the results from immunostaining for the mitosis-specific antibody anti-phosphohistone H3 (PHH3 mitotic index [MI]) with standard MF counts (H&E MI) and the Ki-67 labeling index (LI). The relationship between these proliferation indices and prognosis was investigated in a retrospective series of 265 meningiomas. The PHH3 staining method yielded greater sensitivity in the detection of MFs and facilitated MF counting. Mitotic thresholds of H&E MI of 4 or more per 10 high-power fields (HPF) and PHH3 MI of 6 or more per 10 HPF were found as the most appropriate prognostic cutoff values for the prediction of recurrence-free survival. All 3 proliferation indices were univariately associated with recurrences and deaths. In contrast with the Ki-67 LI, H&E MI and PHH3 MI also remained as independent predictors in the multivariate Cox hazards modeling (P = .0007 and P = .0004, respectively).