[DNA microarray analysis in nerve biopsies of patients with vasculitic neuropathy]. / Neuropathies des vascularites: l'apport des techniques à puces d'ADN dans les biopsies de nerf.

DNA microarray analysis is a powerful tool for simultaneous analysis and comparison of gene products expressed in normal and diseased tissues. We used this technique to identify differentially expressed genes (DEGs) in nerve biopsy samples of vasculitic neuropathy (VAS) patients. We find novel previously uncharacterized genes of relevance to VAS pathogenesis. Genes upregulated in VAS include IGLJ3, IGHG3, IGKC, and IGL, which all function in B-cell selection or antigen recognition of B cells. Other upregulated genes are chemokines, such as CXCL9 and CCR2 and CX3CR1. Allograft inflammatory factor-1 (AIF-1), a modulator of immune response is upregulated in VAS. We demonstrate by immunolocalisation the expression of AIF-1 in vascular smooth muscle cells, suggesting a role for AIF-1 in vascular remodeling in VAS. Microarray-based analysis of human nerve biopsies shows distinct gene expression patterns in VAS. DEGs might provide clues to the pathogenesis of this condition and help define potential targets for therapeutics.

Gene expression analysis of normal appearing brain tissue in an animal model for multiple sclerosis revealed grey matter alterations, but only minor white matter changes.

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS). Recent studies suggest that, beside focal lesions, diffuse inflammatory and degenerative processes take place throughout the MS brain. Especially, molecular alterations in the so-called normal appearing white matter suggest the induction of neuroprotective mechanisms against oxidative stress preserving cellular homeostasis and function. In this study we investigated whether in an animal model for MS, namely in experimental autoimmune encephalomyelitis (EAE), similar changes occur. We isolated normal appearing white and grey matter from the corpus callosum and the above lying cerebral cortex from DA rats with rMOG-induced EAE and carried out a gene expression analysis. Examination of corpus callosum revealed only minor changes in EAE rats. In contrast, we identified a number of gene expression alterations in the cerebral cortex even though morphological and cellular alterations were not evident. One of the most striking observations was the downregulation of genes involved in mitochondrial function as well as a whole set of genes coding for different glutamate receptors. Our data imply that molecular alterations are present in neurons far distant to inflammatory demyelinating lesions. These alterations might reflect degenerative processes induced by lesion-mediated axonal injury in the spinal cord. Our results indicate that the MOG-induced EAE in DA rats is a valuable model to analyze neuronal alterations due to axonal impairment in an acute phase of a MS-like disease, and could be used for development of neuroprotective strategies.

RNA profiling of MS brain tissues.

Recently, the introduction of RNA profiling using microarray technology has helped to elucidate gene expression changes in diseased tissue samples from postmortem human brains. Especially, in the field of multiple sclerosis (MS) research, microarray-based RNA profiling has been applied in the hope to identify disease specific alterations. The lack of good biomarkers for diagnostic as well as for prognostic purposes, but also the need for new drug targets and for a better understanding of the pathophysiology, makes this technique a valuable tool. Different RNA profiling approaches have been used, addressing distinct scientific questions. MS brain tissue samples have been proven to be an appropriate source for RNA profiling to investigate molecular pathomechanisms. This work discusses the critical parameters for RNA profiling of MS brain tissues, and reviews the results obtained by microarray studies analyzing differential gene expression in MS brain tissues.

The calsyntenins--a family of postsynaptic membrane proteins with distinct neuronal expression patterns.

We have identified two novel postsynaptic membrane proteins that are highly similar to calsyntenin-1 in their extracellular parts but vary considerably in their cytoplasmic segment. Calsyntenin-1 has recently been identified in our lab as a postsynaptic membrane protein with a highly acidic cytoplasmic segment with putative Ca(2+)-binding capacity (Vogt et al., 2001, Mol. Cell. Neurosci. 17: 151-166). Based on their structural similarity to calsyntenin-1, we have called the novel proteins calsyntenin-2 and -3, respectively. By immunoelectron microscopy, the calsyntenin protein family was localized in the postsynaptic membrane of excitatory central nervous system (CNS) synapses. In situ hybridization analysis revealed that calsyntenin-1 was abundant in most neurons of the CNS with relatively little variation in its expression level. Calsyntenin-2 and -3 expressions varied much more with highest levels in GABAergic neurons. Based on their distinct expression patterns and the differences in their cytoplasmic segments, we suggest a cell-type-specific functional role for the three calsyntenins in excitatory synaptic transmission.

Calsyntenin-1, a proteolytically processed postsynaptic membrane protein with a cytoplasmic calcium-binding domain.

In a screen for proteins released from synapse-forming spinal cord neurons, we found the proteolytically cleaved N-terminal fragment of a transmembrane protein localized in the postsynaptic membrane of both excitatory and inhibitory synapses. We termed this protein calsyntenin-1, because it binds synaptic Ca2+ with its cytoplasmic domain. By binding Ca2+, calsyntenin-1 may modulate Ca2+-mediated postsynaptic signals. Proteolytic cleavage of calsyntenin-1 in its extracellular moiety generates a transmembrane stump that is internalized and accumulated in the spine apparatus of spine synapses. Therefore, the synaptic Ca2+ modulation by calsyntenin-1 may be subject to regulation by extracellular proteolysis in the synaptic cleft. Thus, calsyntenin-1 may link extracellular proteolysis in the synaptic cleft and postsynaptic Ca2+ signaling.

Familial dementia caused by polymerization of mutant neuroserpin.

Aberrant protein processing with tissue deposition is associated with many common neurodegenerative disorders; however, the complex interplay of genetic and environmental factors has made it difficult to decipher the sequence of events linking protein aggregation with clinical disease. Substantial progress has been made toward understanding the pathophysiology of prototypical conformational diseases and protein polymerization in the superfamily of serine proteinase inhibitors (serpins). Here we describe a new disease, familial encephalopathy with neuroserpin inclusion bodies, characterized clinically as an autosomal dominantly inherited dementia, histologically by unique neuronal inclusion bodies and biochemically by polymers of the neuron-specific serpin, neuroserpin. We report the cosegregation of point mutations in the neuroserpin gene (PI12) with the disease in two families. The significance of one mutation, S49P, is evident from its homology to a previously described serpin mutations, whereas that of the other, S52R, is predicted by modelling of the serpin template. Our findings provide a molecular mechanism for a familial dementia and imply that inhibitors of protein polymerization may be effective therapies for this disorder and perhaps for other more common neurodegenerative diseases.

Hospital offers cardiac crisis program to industry.

A university medical center has initated a cardiac crisis plan that reaches out to industry to promote preventive health care among employees. The program described here served as a marketing tool for the medical center to establish its credibility among business leaders.