Developmental immunohistochemistry of bifunctional protein in human brain

Immunohistochemical Localization of Peroxisomal Enzymes During Rat Embryonic Development

Peroxisomes are cytoplasmic organelles involved in a variety of metabolic pathways. Thus far, the morphological and biochemical features of peroxisomes have been extensively characterized in adult tissues. However, the existence of congenital peroxisomal disorders, primarily affecting tissue differentiation, emphasizes the importance of these organelles in the early stages of organogenesis. We investigated the occurrence and tissue distribution of three peroxisomal enzymes in rat embryos at various developmental stages. By means of a highly sensitive biotinyl-tyramide protocol, catalase, acyl-CoA oxidase, and ketoacyl-CoA thiolase were detected in embryonic tissues where peroxisomes had not thus far been recognized, i.e., adrenal and pancreatic parenchyma, choroid plexus, neuroblasts of cranial and spinal ganglia and myenteric plexus, and chondroblasts of certain skeletal structures. In other tissues, i.e., gut epithelium and neuroblasts of some CNS areas, they were identified earlier than previously. In select CNS areas, ultrastructural catalase cytochemistry allowed identification of actively proliferating organelles at early developmental stages in several cell types. Our data show that in most organs maturation of peroxisomes parallels the acquirement of specific functions, mainly related to lipid metabolism, thus supporting an involvement of the organelles in tissue differentiation.

Absence of functional peroxisomes from mouse CNS causes dysmyelination and axon degeneration

Peroxisomal metabolism is essential for normal brain development both in men and in mice. Using conditional knock-out mice, we recently showed that peroxisome deficiency in liver has a severe and persistent impact on the formation of cortex and cerebellum, whereas absence of functional peroxisomes from the CNS only causes developmental delays without obvious alteration of brain architecture. We now report that a substantial fraction of the latter Nes-Pex5 knock-out mice survive into adulthood but develop progressive motoric and coordination problems, impaired exploration, and a deficit in cognition and die before the age of 6 months. Histopathologically, both the white and gray matter of the CNS displayed a region-specific accumulation of neutral lipids, astrogliosis and microgliosis, upregulation of catalase, and scattered cell death. Nes-Pex5 knock-out mice featured a dramatic reduction of myelin staining in corpus callosum, whereas cerebellum and other white matter tracts were less affected or unchanged. This was accompanied by a depletion of alkenylphospholipids in myelin and differentially reduced immunoreactivity of myelin proteins. EM analysis revealed that myelin wrappings around axons did still form, but they showed a reduction in thickness relative to axon diameters. Remarkably, multifocal axonal damage occurred in the corpus callosum. Thereby, debris accumulated between axolemma and inner myelin surface and axons collapsed, although myelin sheaths remained present. These anomalies of myelinated axons were already present in juvenile mice but aggravated in adulthood. Together, loss of CNS peroxisomal metabolism both affects myelin sheaths and axonal integrity possibly via independent pathways.

Expression of catalase mRNA and protein in adult rat brain: detection by nonradioactive in situ hybridization with signal amplification by catalyzed reporter deposition (ISH-CARD) and immunohistochemistry (IHC)/immunofluorescence (IF)

Catalase, the classical peroxisomal marker enzyme, decomposes hydrogen peroxide and is involved in the antioxidant defense mechanisms of mammalian cells. In addition, catalase can oxidize, by means of its peroxidatic activity, a variety of substrates such as methanol and ethanol, producing the corresponding aldehydes. The involvement of brain catalase in the oxidation of ethanol is well established, and severe afflictions of the CNS in hereditary peroxisomal diseases (e.g., Zellweger syndrome) are well known. Whereas the distribution of catalase in the CNS has been investigated by enzyme histochemistry and immunohistochemistry (IHC), very little is known about the exact localization of catalase mRNA in brain. Here we report the application of a tyramine/CARD (catalyzed reporter deposition)-enhanced nonradioactive in situ hybridization (ISH) protocol for detection of catalase mRNA in sections of perfusion-fixed, paraffin-embedded rat brain. Catalase mRNA could be demonstrated in a large number of neurons throughout the rat brain as a distinct cytoplasmic staining signal with excellent morphological resolution. Compared to our standard ISH protocol, the CARD-enhanced protocol for catalase mRNA detection in rat brain showed higher sensitivity and significantly better signal-to-noise ratio. In parallel IHC experiments, using an antigen retrieval method consisting of combined trypsin digestion and microwave treatment of paraffin sections, the catalase antigen was found as distinct cytoplasmic granules in most catalase mRNA-positive neurons. In addition, catalase-positive granules, presumably peroxisomes, were found by confocal laser scanning microscopy in glial cells, which were identified by double labeling immunofluorescence for GFAP and CNPase for astroglial cells and oligodentrocytes, respectively. The excellent preservation of morphology and sensitive detection of both mRNA and protein in our preparations warrant the application of the protocols described here for systematic studies of catalase and other peroxisomal proteins in diverse pathological conditions such as Alzheimer's disease and aging.

Presence and inducibility of peroxisomes in a human glioblastoma cell line

We investigated the effect of the peroxisomal proliferator (PP) perfluorodecanoic acid (PFDA), alone or in combination with 9-cis-retinoic acid (RX) on the human glioblastoma cell line Lipari (LI). Cell proliferation, apoptotic rate, peroxisome morphology and morphometry, peroxisomal enzyme activities and the presence of peroxisome proliferator-activated receptors (PPARs) were examined. We show that PFDA alone produces pleiotropic effects on LI cells and that RX enhances some of these effects. Peroxisomal number and relative volume, as well as palmitoyl-CoA oxidase activity and protein, are increased by PFDA treatment, with a synergistic effect by RX. The latter, alone or in association with PFDA, induces catalase activity and protein, increases apoptosis and decreases cell proliferation. PPAR isotypes alpha and gamma were detected in LI cells. While the former is apparently unaffected by either treatment, the latter increases in response to PFDA, independent of the presence of RX. The results of this study are discussed in terms of PPARalpha activation and PPARgamma induction by PFDA, by either a direct or an indirect mechanism.

Immunohistochemical expression of doublecortin in the human cerebrum: comparison of normal development and neuronal migration disorders

Immunohistochemical expression of the doublecortin (DCX) gene product was investigated in cerebral cortices from 33 normal developing human, aged 9 gestational weeks (GW) to 29 years, and from 26 patients with various neuronal migration disorders, aged 19 GW to 34 years. DCX immunoreactivity was detected predominantly in the fetal cerebral cortex. The neurons in the cortical plate (CP) exhibited positive labeling at 9 GW. Staining was the most marked intense at 12-20 GW, and gradually decreased thereafter, only relatively weak immunoreactivity remaining in pyramidal cells. Comparison of the immunohistochemical characteristics of DCX and those of nestin and vimentin indicated the early expression of DCX in neuroepithelial stem cells of the subventricular germinal layer, as well as in neurons of the CP. The most marked intense expression in the period of neuronal migration strongly indicated its role in neuronal migration. The abnormal distribution of DCX immunolabeling in the cerebral cortex was associated with a neuronal disarrangement in some migration disorders, such as Miller-Dieker syndrome and Fukuyama congenital muscular dystrophy. Decreased DCX immunolabeling was demonstrated in fetuses and infants with Zellweger syndrome, implicating DCX in the neuronal migration abnormality in this syndrome.

Developmental and pathological expression of peroxisomal enzymes: their relationship of D-bifunctional protein deficiency and Zellweger syndrome

We present the developmental changes of peroxisomal enzymes, catalase, L-bifunctional protein (L-BF) and D-bifunctional protein (D-BF), in the normal brains, and patients with D-BF deficiency, a new peroxisomal disease. D-BF immunoreactivity was observed in controls as early as 13 gestational weeks (GW) and increased with maturation. The adult pattern with fine granule staining of somata and dendrites became apparent in adolescence. L-BF appeared at 20 GW in the cerebral cortex and Purkinje cells and positive glia appeared early in the white matter at 17 GW, and then increased with age. Catalase-positive neurons were identified in the same manner as L-BF, D-BF deficiency in both fetus and infant showed markedly diminished enzyme immunoreactivity. Patients demonstrate reduced D-BF expression. Zellweger syndrome shows decreased expression for the three proteins. This study shows that the peroxisomal enzymes may be closely related to neuronal maturation and gliogenesis in human brain and to disturbance of neuronal migration as seen in Zellweger syndrome significant. D-BF deficiency may exhibit a range of symptoms during the neonatal and early infantile periods some of which may be similar to Zellweger syndrome.

A novel peroxisomal enzyme, D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl-CoA dehydrogenase bifunctional protein: its expression in the developing human brain

D-bifunctional protein, which is a newly recognized peroxisomal enzyme (D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl-CoA dehydrogenase), demonstrates a characteristic development of pattern in the human brain. At 13 gestational weeks (GW), D-bifunctional protein immunoreactivity first appeared in the brain. Each neuron exhibited increased immunoreactivity along with growth in size as age increased and size with age. Glial cells in the white matter showed immunoreactivity after 30 GW. On the other hand, the L-bifunctional protein immunoreactivity was reported in neurons from 23 or 25 GW and in the white matter from 12 or 14 GW. Because of polymicrogyria in conditions such as infantile Refsum disease and infantile adrenoleukodystrophy, peroxisomal enzymes are thought to play an important role in neuronal migration and possibly myelination. D-bifunctional protein may be relevant to neuronal migration and L-bifunctional protein may be involved in axonal growth and synaptic development. This study is designed to access the ontogeny of D-bifunctional protein in the human brain.

Peroxisomal bifunctional enzyme deficiency: serial neurophysiological examinations of a case

We report on a case of 21-month-old girl with peroxisomal bifunctional enzyme deficiency, which was diagnosed by means of complementation analysis. Serial neurophysiological examinations were also carried out. The motor and sensory nerve conduction velocities of the median nerve showed lower borderline values at 3 months of age and were within range at 11 months of age. Later, those velocities gradually decreased. The electrically elicited blink reflex at 3 months of age showed the prolongation of latencies of R1, R2 and R2' and the interpeak latencies of R1-R2 and R1-R2'. Furthermore, R1, R2 and R2' showed prolonged latencies at 11 months of age and were absent at 15 months of age. The auditory brainstem response (ABR) showed, bilaterally, normal latency of wave I, prolonged interpeak latencies of waves I-V. At 11 months of age, waves III and IV-V of ABR were detected, but their amplitude was very low. At the age of 15 months ABR was absent. These results and the following report are valuable for understanding the pathogenesis of neurological symptoms.

Expression of the adrenoleukodystrophy protein in the human and mouse central nervous system

The gene mutated in X-linked adrenoleukodystrophy (ALD), a progressive demyelinating disease, codes for a protein (ALDP) involved in very-long-chain fatty acid (VLCFA) transport. The expression of ALDP and of two peroxisomal enzymes involved in beta-oxidation of VLCFA, acyl-CoA oxidase, and catalase was studied in human and mouse brain. The pattern of expression was similar in both species. While acyl-CoA oxidase and catalase are found in all types of CNS cells, including neurons and oligodendrocytes, ALDP expression is restricted mostly to the white matter and endothelial cells. ALDP is highly expressed in astrocytes and microglial cells in vivo and in regenerating oligodendrocytes in vitro. In contrast, in vivo, ALDP is detected in much fewer oligodendrocytes and quantitative Western blot analysis confirmed the lower abundance of ALDP in these cells than in astrocytes. Only oligodendrocytes localized in corpus callosum, internal capsules, and anterior commissure express ALDP at levels comparable to those seen in astrocytes. In ALD, demyelination is first detected in these white matter regions, suggesting that the ALD gene mutation selectively affects those oligodendrocytes strongly expressing ALDP. Because of their failure to express ALDP, microglia and astrocytes may also contribute to demyelination in ALD patients.

Peroxisomal disorders: clinical aspects

Peroxisomal disorders are divided into two groups from a clinical point of view. Diseases in the first group, peroxisome-deficient disorders (PDD), Zellweger-like syndrome, and isolated deficiencies of peroxisomal beta-oxidation enzymes, are characterized by common clinical features including psychomotor retardation, hypotonia, hepatic dysfunction and visual disturbance. The second group includes diseases with a unique manifestation, such as X-linked adrenoleukodystrophy, hyperoxaluria type I and rhizomelic chondrodysplasia punctata. We investigated clinical aspects and the genetic basis of PDD, and the significance of peroxisomes in the development of human brain. Neuroradiological and neurophysiological studies revealed that thick cortex, colpocephaly and multifocal spikes were characteristic findings of PDD patients in the early infantile period. Cytogenetic studies elucidated the presence of eleven complementation groups among PDD, indicating the presence of eleven pathogenic genes for PDD. Molecular studies elucidated two of these genes, PAF-1 and PXR-1. Immunohistochemical studies clarified that the catalase-positive neurons appeared in the basal ganglia, thalamus, and cerebellum at 28 weeks of gestation, and in the cortex at 35 weeks. Immunopositive glial cells appeared from the deep to superficial white matter with increasing gestational age. These results suggest the important role of peroxisomes in neuronal maturation and myelinogenesis.

On the role of the peroxisome in ontogeny, ageing and degenerative disease

This article reviews the available data on the role of the peroxisome in the growth, differentiation and degeneration of mammalian tissues. Developmental progressions of peroxisomes are described, along with the influence of inhibitors of peroxisomal enzymes, peroxisome proliferators and morphogenetic agents on the ontogeny of experimental animals. The role of the peroxisome in protecting tissues from damage by oxygen free radicals is also described, as is the changing role of the peroxisome in the ageing animal. Amongst the degenerative diseases which have been associated with free radical damage are cancer, atherosclerosis, muscular dystrophy, rheumatoid arthritis and the senile degeneration of brain function. In all these conditions, the major characteristics of molecular damage have been considered, along with the particular role of the peroxisome in alleviating these effects. Proposals for further research into peroxisomal function during ontogeny and the degenerative changes associated with ageing are developed, and the possibility of palliative treatments discussed.

The importance of tissue fixation for light microscopic immunohistochemical localization of peroxisomal proteins: the superiority of Carnoy's fixative over Baker's formalin and Bouin's solution

We have compared the effects of fixation with three commonly used fixatives upon preservation of the antigenicity of six peroxisomal proteins in rat liver using both immunohistochemical staining and Western blotting of fixed tissue extracts. The immunoreactivity of all six peroxisomal proteins was well preserved and peroxisomes were clearly identified in material fixed in Carnoy's fixative. Moreover, the corresponding proteins stained well in Western blots prepared from extracts of Carnoy-fixed material. The intensity of the immunohistochemical staining was reduced at different rates for individual peroxisomal proteins after fixation in Baker's formalin, but peroxisomes were still well visualized with antibodies to catalase and some beta-oxidation enzymes. No evidence of immunohistochemical staining for any peroxisomal antigens was obtained after fixation in Bouin's fluid. For detection of the antibody binding sites in Carnoy's fixed material, the avidin-biotin-peroxidase complex (ABC) with aminoethyl carbazole as chromogen was found to be superior to the methods of peroxidase-antiperoxidase/diaminobenzidine and protein A-gold with silver intensification. Using Carnoy-fixative and the ABC-method, we demonstrate light microscopic immunohistochemical localization of peroxisomal antigens in several rat tissues as well as in human post-mortem liver.