Junko Takahashi

PML nuclear bodies and neuronal intranuclear inclusion in polyglutamine diseases

In polyglutamine diseases, accumulation in the nucleus of mutant proteins induces the formation of neuronal intranuclear inclusions (NIIs). The nucleus is compartmentalized into structural and functional domains, which are involved in NII formation. Promyelocytic leukemia protein (PML), a major component of nuclear bodies, and mSin3A, a component of the transcription co-repressor complex, were used to investigate how the intranuclear domains/sites relate to NII formation in SCA2, SCA3, SCA7, SCA17 and DRPLA brains. We demonstrate that the size of PML-positive intranuclear structures was larger in pathological brains than in control ones and that these structures contained mutant proteins. PML colocalized only with small NIIs, which maintained the ring-like structure of normal nuclear bodies. Enlarged ring-like PML-positive structures, devoid of mutant proteins, were also found and might represent structures where mutant polyglutamine proteins have been successfully processed. These data suggest that NIIs originate from nuclear bodies, where mutant proteins accumulate for degradation.

Neuronal intranuclear hyaline inclusion disease with polyglutamine-immunoreactive inclusions

Abstract Neuronal intranuclear hyaline inclusion disease (NIHID) is a group of neurodegenerative disorders characterized by the presence of intranuclear inclusions in neurons (NIs). We report here clinicopathological findings of a 25-year-old female patient who died after 13 years of a clinical course characterized by progressive gait disturbance and movement disorders. Histological examination revealed widespread NIs with neuronal loss in restricted regions; neuronal loss was severe in the subthalamic nucleus, internal pallidum, substantia nigra, Edinger-Westphal nucleus and Purkinje cell layer. Quantification of the NIs combined with a graded evaluation of neuronal loss revealed an overall tendency for more severe neuronal loss to be accompanied by a lower frequency of NIs. A morphological similarity to the nuclear inclusions recently identified in several CAG repeat diseases prompted us to examine the immunolocalization of ubiquitin and expanded polyglutamine stretches, which demonstrated the presence of ubiquitin at the periphery of most NIs. An expanded polyglutamine stretch was seen in the center of limited number of NIs. These findings indicate that abnormal fragments such as expanded polyglutamine regions are incorporated into the inclusion, aggregated in its center, and thereby metabolized by a ubiquitin-dependent proteolytic pathway. Although it remains to be elucidated how the formation of NIs is related to neuronal degeneration, our findings suggest that NIs are formed in the process of sequestering or degrading abnormal protein fragments and formation of NIs may not be immediately toxic to neurons.

Tyrosine hydroxylase-immunoreactive neurons are decreased in number in the cerebral cortex of Parkinson's disease

Tyrosine hydroxylase (TH)‐immunoreactive (IR) neurons and their relationship with Lewy bodies were investigated in Parkinsons disease. Using anti‐TH and/or anti‐ubiquitin antibodies, we evaluated the cerebral cortices included superior frontal gyrus, precentral gyrus, postcentral gyrus, inferior temporal gyrus, cuneus, cingulate gyrus, short and long gyri of insula, and parahippocampal gyrus from 18 autopsy cases of Parkinsons disease and 16 controls. The appearance of TH‐IR neurons in cerebral cortices was suggestive of non‐pyramidal interneurons. The mean number of TH‐IR neurons and the density of TH‐IR fibers in Parkinsons disease were decreased in comparison with the controls. The cognitive impairment in Parkinsons disease has been accounted for by the lesions of the basal nucleus of Meynert, the locus ceruleus, and the cortical Lewy bodies in the cerebral cortex. In addition to these lesions, the global loss of non‐pyramidal TH‐IR cortical neurons and TH‐IR fibers would induce the dysfunction of higher‐order control of the neocortex and the limbic system in Parkinsons disease. Double‐immunostaining with anti‐TH and anti‐ubiquitin antibodies did not show the TH‐IR neuron with cortical Lewy body in the cerebral cortices of Parkinsons disease. In the cerebral cortices of Parkinsons disease, TH‐IR non‐pyramidal neurons in which cortical Lewy body is not formed decreased in number.

An autopsy case of Pena-Shokeir syndrome: severe retardation of skeletal muscle development compared with neuronal abnormalities.

An infant with multiple joint ankyloses, facial anomalies, and pulmonary hypoplasia, features similar to the phenotype of Pena-Shokeir syndrome, was examined at autopsy. Histological examination of the skeletal muscles revealed many small muscle fibers in a mixed, not group, distribution, although the structure of them was normally arranged. Histochemical assessment of adenosine triphosphatase (ATPase) activity of the iliopsoas muscle demonstrated the failure of the differentiation into type I fibers and the retardation of the skeletal muscle. At the same time, severe pulmonary hypoplasia, which was the likely cause for the retardation of the respiratory system, was found. In contrast to these numerous pathologic changes in the skeletal muscles, no significant abnormalities were observed in the central nervous system except for a somewhat immature external appearance; however, an examination of the spinal cord could not be carried out. Overall, this pattern of pathology suggests the possibility that developmental disorders of the mesenchyme are the primary contributors to the pathogenesis of Pena-Shokeir syndrome, while the immaturity of the central nervous system is involved to a lesser degree.

Expression of vascular endothelial growth factor (VEGF) and its two receptors in diffusely infiltrating astrocytomas and relationship to proliferative activity of tumor cells.

We studied the relationships among vascular endothelial growth factor (VEGF), its receptors (Flt1 and Flk1), and MIB-1. Their expression in 47 diffusely infiltrating astrocytomas obtained at surgery or autopsy was investigated by the ABC method and analyzed quantitatively. The positive rate of VEGF in tumor cells was higher than that in endothelial cells, and Flk1 was lower in tumor cells (P<0.01, 0.01), whereas Flt1 in both tumor cells and endothelial cells was found at similar levels (P>0.05). In tumor cells, VEGF became high with increased histological grades (P<0.01), whereas both Flt1 and Flk1 were higher in grade 4 than in grades 2 and 3 (P<0.01, 0.05). VEGF, Flt1, and Flk1 in endothelial cells were also highly expressed in grade 4 (P<0.01). The distribution of MIB-1-positive nuclei in grade 4 was similar to VEGF, and the percent of positivity from grade 2 to grade 4 also increased (P<0.01). There was a linear positive correlation between VEGF and both Flt1 and Flk1 in both tumor cells and endothelial cells (P<0.01). So was the percent of positivity with VEGF, Flt1, and Flk1 in tumor cells and endothelial cells (P<0.01). The experiment suggests that VEGF may act as a growth factor for both endothelial cells and tumor cells. VEGF, Flt1, and Flk1 can be considered as indicators of the malignancy potential of diffusely infiltrating astrocytomas. The expression of VEGF and the two receptors may be affected by the proliferative activity of tumor cells.

Bax-induced apoptosis not demonstrated in the congenital toxoplasmosis in mice

A prominent neuropathological change observed in a murine model of congenital toxoplasmosis is cerebral cortical hypoplasia. In the early embryonic life of toxoplasmosis mice, the number of apoptotic cell observed in cerebral cortex is increased, indicating that increased number of apoptotic cells might relate to the pathogenetic mechanism of the cortical hypoplasia. Immunohistochemical expression of apoptosis-related factors, Bcl-2 and Bax has been studied in fetal murine brains infected with toxoplasma and in controls. Paraffin sections of the fetal brains on embryonic day (ED) 10, 12, 14, 16 and 18 were applied for the immunostains of Bcl-2 and Bax. Totally, 47 experimental animals (ED10: n=8, ED12: n=6, ED14: n=12, ED16: n=6, ED18: n=15) and 48 control animals (ED10: n=6, ED12: n=8, ED14: n=9, ED16: n=9, ED18: n=16) were examined. Bcl-2 positive cells were detected on ED10, whereas Bax positive cells appeared on ED14. No difference of Bcl-2 and Bax expression between toxoplasmosis and control groups was detected, suggesting that there is no clear relation between Bax-induced apoptosis and cortical dysplasia in congenital toxoplasmosis.