Reorganization of nuclear compartments of type a neurons of trigeminal ganglia in response to inflammatory injury of peripheral nerve endings

In this study we have taken advantage of the high nuclear responsiveness of type A sensory ganglia neurons to variations of cellular activity to investigate the reorganization and dynamics of nuclear compartments involved in transcription and RNA processing in response to neuronal injury. As experimental model we have used the inflammatory injury of the peripheral nerve endings induced by formalin injection in the areas of ophthalmic/maxillary nerve distribution. We have performed immunofluorescence and confocal laser microscopy analysis with specific antibodies for different nuclear compartments and ultrastructural analysis. The initial response to neuronal injury, within the 3 days post-injury, consisted of chromatin condensation, reduction in the expression level of acetylated histone H4, accumulation of perichromatin granules, reorganization of splicing factors in prominent nuclear speckles, reduction in the number of Cajal bodies and nucleolar alterations. These changes tended to revert by day 7 post-injury and are consistent with a transient inhibition of transcription and RNA processing. Moreover, we have observed an early and sustained expression of the transcription factor c-Jun. These results illustrate the transcription-dependent organization of nuclear compartments in type A trigeminal neurons and also support the importance of the nuclear response to axonal injury as a key component in the regenerative capacity of this neuronal population. © 2004 Kluwer Academic Publishers.This work was supported by the following grants: “Centro de Investigación de Enfermedades Neurológicas (CIEN)’’, “Instituto de Salud Carlos III (Madrid, Spain); “Dirección General de Investigación’’ of Spain (BFI2002-0454); and “Fundación Marqués de Valdecilla’’ (A04/03) of Santander, Spain.Peer Reviewe

Nuclear compartmentalization and dynamics of the poly(A)-binding protein nuclear 1 (PABPN1) inclusions in supraoptic neurons under physiological and osmotic stress conditions

Nuclear aggregation of the expanded polyalanine tract in the poly(A)-binding protein nuclear 1 (PABPN1) is the pathological hallmark of oculopharyngeal muscular dystrophy. However, wild type PABPN1 aggregates into nuclear inclusion in oxytocin-producing neurons under physiological conditions. In this study we have analyzed the nuclear organization and dynamics of PABPN1 inclusions in oxytocin-producing neurons. We demonstrated that PABPN1 inclusions represent a distinct compartment of the interchromatin region. They establish a spatial relationship with nuclear speckles, Cajal bodies and clastosomes. PABPN1 inclusions accumulate poly(A) RNA, but do not concentrate highly expressed mRNAs in oxytocin producing neurons and the mRNA-binding proteins hnRNP C, Y14 and REF. PABPN1 inclusions are dynamic structures that appear during the postnatal period and their number decrease in response to the activation of transcription. Our results support that the RNA retained in the PABPN1 inclusions is a noncoding regulatory RNA involved in some aspects of nuclear RNA metabolism. © 2007 Elsevier Inc. All rights reserved.This work was supported by the following grants: “Dirección General de Investigacion” of Spain (BFU2005-01030), “Fundación Marqués de Valdecilla” (API05/04) from Santander, Spain and “Centro de Investigación en Red sobre Enfermedades Neurodegenerativas” (CIBERNED, CB06/05/0037) from Spain.Peer Reviewe

PML bodies in reactive sensory ganglion neurons of the Guillain- Barré syndrome

Acute inflammatory demyelinating polyneuropathy (AIDP) is a type of Guillain-Barré syndrome (GBS) characterized by primary nerve demyelination sometimes with secondary axonal degeneration. Studies on the fine structure of dorsal root ganglia in AIDP are lacking. Our aim was to investigate the cytology and nuclear organization of primary sensory neurons in AIDP with axonal injury using ultrastructural and immunohistochemical analysis. The light cytology of the L5 dorsal ganglion showed the characteristic findings of neuronal axonal reaction. The organization of chromatin, nucleolus, Cajal bodies, and nuclear pores corresponded to transcriptionally active neurons. However, the hallmark of the nuclear response to axonal injury was the formation of numerous nuclear bodies (NBs; 6.37 ± 0.6, in the AIDP, vs. 2.53 ± 0.2, in the control, mean ± SDM), identified as promyelocytic leukemia (PML) bodies by the presence of the protein PML. In addition to PML protein, nuclear bodies contained SUMO-1 and the transcriptional regulators CREB-binding protein (CBP) and glucocorticoid receptor (GR). The presence of proteasome 19S was also detected in some nuclear bodies. We suggest that neuronal PML bodies could regulate the nuclear concentration of active proteins, a process mediated by protein interactions with PML and SUMO-1 proteins. In the AIDP case, the proliferation of PML bodies may result from the overexpression of some nuclear proteins due to changes in gene expression associated with axonal injury. © 2004 Elsevier Inc. All rights reserved.This work was supported by the following grants: “Centro de Investigación de Enfermedades Neurológicas (CIEN)”, “Instituto de Salud Carlos III (Madrid, Spain)”; “Dirección General de Investigacion” from Spain (BFI2002-0454); and “Fundación Marqués de Valdecilla” (A04/03) from Santander, Spain.Peer Reviewe

The PML-nuclear inclusion of human supraoptic neurons: A new compartment with SUMO-1- and ubiquitin-proteasome-associated domains

It is well known that the cell nucleus is organized in structural and functional compartments involved in transcription, RNA processing and protein modifications such as conjugation with SUMO-1 and proteolysis. Promyelocytic leukaemia (PML) bodies are dynamic nuclear structures that concentrate PML protein, SUMO-1 and several sumoylated and non-sumoylated protein regulators of nuclear functions. PML bodies and their associated CBP has been involved in neuronal survival. By light and electron microscopy immunocytochemistry and in situ hybridization we reported the presence, in non-pathological conditions, of a large PML-nuclear inclusion (PML-NI) in human supraoptic neurons. This inclusion appears as a single nuclear structure composed of a capsule enriched in PML, SUMO-1 and CBP proteins and a central lattice of filaments immunoreactive for class III β-tubulin, ubiquitinated proteins and proteasomes. Furthermore, the PML-NI concentrates the SUMO-conjugating enzyme E2 (UBC9). The PML-NI may be considered a nuclear factory involved in sumoylation and proteolysis via ubiquitin-proteasome system, two nuclear pathways engaged in the control of the nucleoplasmic concentration of active transcriptional regulators. Interestingly, the structural and molecular organization of the PML-NI is related to the Marinesco bodies, age-associated ubiquitinated intranuclear inclusions, and to the intranuclear rodlets enriched in class III β-tubulin, which are nuclear structures markedly decreased in Alzheimer's disease. © 2005 Elsevier Inc. All rights reserved.This study was supported by “Dirección General de Investigación Científica” from Spain (BFI2002-0454; BFU2005-01030), “Fondo de Investigación Sanitaria” from Spain (Red CIEN C03-C06) and Fundación Marqués de Valdecilla from Santander (API/05/04).Peer Reviewe

Cajal body number and nucleolar size correlate with the cell body mass in human sensory ganglia neurons

This paper studies the cell size-dependent organization of the nucleolus and Cajal bodies (CBs) in dissociated human dorsal root ganglia (DRG) neurons from autopsy tissue samples of patients without neurological disease. The quantitative analysis of nucleoli with an anti-fibrillarin antibody showed that all neurons have only one nucleolus. However, the nucleolar volume and the number of fibrillar centers per nucleolus significantly increase as a function of cell body size. Immunostaining for coilin demonstrated the presence of numerous CBs in DRG neurons (up to 20 in large size neurons). The number of CBs per neuron correlated positively with the cell body volume. Light and electron microscopy immunocytochemical analysis revealed the concentration of coilin, snRNPs, SMN and fibrillarin in CBs of DRG neurons. CBs were frequently associated with the nucleolus, active chromatin domains and PML bodies, but not with telomeres. Our results support the view that the nucleolar volume and number of both fibrillar centers and CBs depend on the cell body mass, a parameter closely related to transcriptional and synaptic activity in mammalian neurons. Moreover, the unusual large number of CBs could facilitate the transfer of RNA processing components from CBs to nucleolar and nucleoplasmic sites of RNA processing. © 2007 Elsevier Inc. All rights reserved.This study was supported by the “Direccion General de Investigacion Cientifica” (Spain; BFU2005-01030), the “Instituto de Salud Carlos III (Spain; CIBERNED), and “Fundación Marqués de Valdecilla” in Santander (Spain; API05/04).Peer Reviewe

Oculopharyngeal muscular dystrophy-like nuclear inclusions are present in normal magnocellular neurosecretory neurons of the hypothalamus

Intranuclear inclusions composed of tubular filaments constitute a pathological hallmark of oculopharyngeal muscular dystrophy (OPMD). Autosomal dominant OPMD is caused by (GCG) repeat expansions in the gene that encodes for poly(A) binding protein nuclear 1 (PABPN1). The mutation results in the expansion of a polyalanine stretch in the N-terminus of the protein. It has been proposed that mutated PABPN1 induces protein aggregation, which in turn causes the formation of the filamentous nuclear inclusions. Here we report the presence of intranuclear inclusions composed of tubular filaments in oxytocin-producing neurons from normal rat hypothalamus. Like OPMD inclusions, the filamentous structures in neurosecretory neurons accumulate PABPN1, poly(A) RNA, ubiquitin and proteasomes. These inclusions do not contain members of Hsp40 and HDJ-2/DNAJ families of chaperones. The proportion of oxytocin-producing neurons that contain inclusions decreases during parturition and lactation (when synthesis and release of oxytocin is maximal) and increases at 1 day post-weaning (when occurs a drastic reduction in the production of the hormone). Thus, PABPN1 filaments in normal neurons are dynamic structures, the appearance of which correlate with changes in cellular activity. These data provide the first physiological evidence that polyalanine expansions are not essential to induce polymerization of PABPN1 into filamentous nuclear inclusions. © Oxford University Press 2004; all rights reserved.This study was supported by grants from ‘Fundación Marqués de Valdecilla, A/05/02’, ‘Ministerio de Ciencia y Tecnologia BFI2002-00454’ and ‘Ministerio de Sanidad y Consumo CIEN-02’ (Spain), ‘Fundação para a Ciência e Tecnologia, POCTI/36547/MGI/00’ (Portugal) and the European Commission ‘QLG2-CT-2001-01673’.Peer Reviewe

Coexistence of protease sensitive and resistant prion protein in 129VV homozygous sporadic Creutzfeldt-Jakob disease: a case report

Introduction: The coexistence of different molecular types of classical protease-resistant prion protein in the same individual have been described, however, the simultaneous finding of these with the recently described protease-sensitive variant or variably protease-sensitive prionopathy has, to the best of our knowledge, not yet been reported. Case presentation: A 74-year-old Caucasian woman showed a sporadic Creutzfeldt-Jakob disease clinical phenotype with reactive depression, followed by cognitive impairment, akinetic-rigid Parkinsonism with pseudobulbar syndrome and gait impairment with motor apraxia, visuospatial disorientation, and evident frontal dysfunction features such as grasping, palmomental reflex and brisk perioral reflexes. She died at age 77. Neuropathological findings showed: spongiform change in the patient"s cerebral cortex, striatum, thalamus and molecular layer of the cerebellum with proteinase K-sensitive synaptic-like, dot-like or target-like prion protein deposition in the cortex, thalamus and striatum; proteinase K-resistant prion protein in the same regions; and elongated plaque-like proteinase K-resistant prion protein in the molecular layer of the cerebellum. Molecular analysis of prion protein after proteinase K digestion revealed decreased signal intensity in immunoblot, a ladder-like protein pattern, and a 71% reduction of PrPSc signal relative to non-digested material. Her cerebellum showed a 2A prion protein type largely resistant to proteinase K. Genotype of polymorphism at codon 129 was valine homozygous. Conclusion: Molecular typing of prion protein along with clinical and neuropathological data revealed, to the best of our knowledge, the first case of the coexistence of different protease-sensitive prion proteins in the same patient in a rare case that did not fulfill the current clinical diagnostic criteria for either probable or possible sporadic Creutzfeldt-Jakob disease. This highlights the importance of molecular analyses of several brain regions in order to correctly diagnose rare and atypical prionopathie

Coexistence of protease sensitive and resistant prion protein in 129VV homozygous sporadic Creutzfeldt-Jakob disease: a case report

Introduction: The coexistence of different molecular types of classical protease-resistant prion protein in the same individual have been described, however, the simultaneous finding of these with the recently described protease-sensitive variant or variably protease-sensitive prionopathy has, to the best of our knowledge, not yet been reported. Case presentation: A 74-year-old Caucasian woman showed a sporadic Creutzfeldt-Jakob disease clinical phenotype with reactive depression, followed by cognitive impairment, akinetic-rigid Parkinsonism with pseudobulbar syndrome and gait impairment with motor apraxia, visuospatial disorientation, and evident frontal dysfunction features such as grasping, palmomental reflex and brisk perioral reflexes. She died at age 77. Neuropathological findings showed: spongiform change in the patient"s cerebral cortex, striatum, thalamus and molecular layer of the cerebellum with proteinase K-sensitive synaptic-like, dot-like or target-like prion protein deposition in the cortex, thalamus and striatum; proteinase K-resistant prion protein in the same regions; and elongated plaque-like proteinase K-resistant prion protein in the molecular layer of the cerebellum. Molecular analysis of prion protein after proteinase K digestion revealed decreased signal intensity in immunoblot, a ladder-like protein pattern, and a 71% reduction of PrPSc signal relative to non-digested material. Her cerebellum showed a 2A prion protein type largely resistant to proteinase K. Genotype of polymorphism at codon 129 was valine homozygous. Conclusion: Molecular typing of prion protein along with clinical and neuropathological data revealed, to the best of our knowledge, the first case of the coexistence of different protease-sensitive prion proteins in the same patient in a rare case that did not fulfill the current clinical diagnostic criteria for either probable or possible sporadic Creutzfeldt-Jakob disease. This highlights the importance of molecular analyses of several brain regions in order to correctly diagnose rare and atypical prionopathie