Matrix metalloproteinases in the adult brain physiology: a link between c-Fos,AP-1 and remodeling of neuronal connections?

Matrix metalloproteinases (MMPs), together with their endogenous inhibitors (TIMPs) form an enzymatic system that plays an important role in a variety of physiological and pathological conditions. These proteins are also expressed in the brain, especially under pathological conditions, in which glia as well as invading inflammatory cells provide the major source of the MMP activity. Surprisingly little is known about the MMP function(s) in adult neuronal physiology. This review describes available data on this topic, which is presented in a context of knowledge about the MMP/TIMP system in other organs as well as in brain disorders. An analysis of the MMP and TIMP expression patterns in the brain, along with a consideration of their regulatory mechanisms and substrates, leads to the proposal of possible roles of the MMP system in the brain. This analysis suggests that MMPs may play an important role in the neuronal physiology, especially in neuronal plasticity, including their direct participation in the remodeling of synaptic connections-a mechanism pivotal for learning and memory.     

PHYLOGENETIC AND TAXONOMIC POSITION OF LEPOCINCLIS FUSCA COMB. NOV. (=EUGLENA FUSCA) (EUGLENACEAE): MORPHOLOGICAL AND MOLECULAR JUSTIFICATION1

We studied the morphological diversity and analyzed the small subunit rDNA sequences of two taxa formerly known as Euglena spirogyra Ehr. and Euglena fusca (Klebs) Lemmermann. Our studies confirmed that the two should have the rank of a species, namely Lepocinclis spirogyroides (Ehr.) Marin et Melkonian and Lepocinclis fusca (Klebs) Kosmala et Zakry? comb. nov. (Euglenophyceae). We are defining new diagnostic features for these species, namely the size and the shape of the cells and the shape of the papillae, as well as designating epitypes for them.     

Conformational solution studies of neuropeptide gamma using CD and NMR spectroscopy.

Neuropeptide gamma is one of the largest members of the tachykinin family of peptides, exhibiting strong agonistic activity towards the NK-2 tachykinin receptor. This peptide was synthesized by the solid-phase method using the Fmoc chemistry. Circular-dichroism spectroscopy (CD) investigations of this peptide were performed in phosphate buffer, in the presence of sodium dodecylsulphate (SDS) micelles and trifluoroethanol (TFE) solutions and in DMSO-d6 using the 2D NMR technique in conjunction with two different theoretical approaches. The first assumes multiconformational equilibrium of the peptide studied characterized by the values of statistical weights of low-energy conformations. These calculations were performed using three different force fields ECEPP/3, AMBER4.1 and CHARMM (implemented in the X-PLOR program). The second method incorporates interproton distance and dihedral angle constraints into the starting conformation using the Simulated Annealing algorithm (X-PLOR program). The CD experiments revealed that although the peptide studied is flexible in polar solvents, a tendency to adopt a helical structure was observed in the hydrophobic environment. The NMR data (NOE effects) indicate a helical or reverse structure in the Ile7-His12 fragment of the peptide studied in DMSO-d6 solution. The results obtained cannot be interpreted in terms of a single conformation. Most of the conformations obtained with the ECEPP/3 force field possess a high content of a helical structure. None of the conformers, obtained with the AMBER4.1 and CHARMM force fields, can be considered as the dominant one. In all conformations several beta-turns were detected and in some cases gamma-turns were also found. But in fact, it is rather difficult to select the position of the secondary element(s) present in the structure of NPgamma in solution. All conformers calculated with the X-PLOR program (with using NMR derived distance and torsion angle constraints) are stabilized by several beta-turns. Common structural motives are a type IV beta-turn in the Gln6-His12 fragment. All conformations obtained using two approaches adopt very similar turn shapes in the middle region of molecule and a random structure on the N- and C-terminal fragments.     

Numerical Analysis of Astragalus cicer Microsymbionts

Thirty-seven rhizobium strains, isolated from root nodules of Astragalus cicer (L.) (cicer milkvetch) deriving from different geographic regions, were compared with the representative strains of the known rhizobial species and genera by numerical analysis of phenotypic characteristics. Our results indicated that Astragalus cicer rhizobia were related to the bacteria of Mesorhizobium species and formed two major phena. One phenon, localized on Mesorhizobium loti branch, contained strains from Poland. Another cluster, placed in the vicinity of M. tianshanense, M. mediterraneum, M. ciceri, and M. huakuii, comprised cicer milkvetch nodule isolates from Canada, Ukraine, and one strain from Poland. The relationship of Astragalus cicer microsymbionts to bacteria of the Mesorhizobium species was also supported by phage typing. Received: 10 February 2000 / Accepted: 8 March 2000     

Phenotype dependent differential effects of interleukin-1beta and amyloid-beta on viability and cholinergic phenotype of T17 neuroblastoma cells

Amyloid-beta accumulation in brains of Alzheimer's disease (AD) victims is accompanied by glial inflammatory reactions and preferential loss of cholinergic neurons. Therefore, the aim of this study was to find out whether proinflamatory cytokine interleukin 1beta (IL1beta) modifies effects of amyloid-beta (Abeta) on viability and cholinergic phenotype of septum derived T17 cholinergic neuroblastoma cells. In nondifferentiated T17 cells (NC) Abeta(25-35) (1 microg/ml) caused no changes in choline acetyltransferase (ChAT) activity, acetylcholine (ACh) release, subcellular distribution of acetyl-CoA, but doubled content of trypan blue positive cells. IL1beta (10 ng/ml) increased ACh release (125%) but did not change other parameters of NC. In the presence of Abeta IL1beta also increased ChAT activity (47%), ACh release (100%) but had no effect on acetyl-CoA distribution and cell viability. Differentiation with retinoic acid and dibutyryl cyclic AMP caused over two-fold increase of ChAT activity and ACh content, four-fold increase of ACh release and about 50% decrease of acetyl-CoA level in the mitochondria. In differentiated cells (DC), Abeta decreased ChAT activity (31%), ACh release (47%) and content of acetyl-CoA (80%) in cell cytoplasmic compartment, whereas IL1beta elevated ChAT activity (54%) and ACh release (32%). IL1beta totally reversed Abeta-evoked inhibition of ChAT activity and ACh release and restored control level of cytoplasmic acetyl-CoA but increased fraction of nonviable cells to 25%. Thus, IL1beta could compensate Abeta-evoked cholinergic deficits through the restoration of adequate expression of ChAT and provision of acetyl-CoA to cytoplasmic compartment in cholinergic neurons that survive under such pathologic conditions. These data indicate that IL1beta possess independent cholinotrophic and cholinotoxic activities that may modify Abeta effects on cholinergic neurons.     

Aftiphilin is a component of the clathrin machinery in neurons

Aftiphilin was identified through a database search for proteins containing binding motifs for the gamma-ear domain of clathrin adaptor protein 1 (AP-1). Here, we demonstrate that aftiphilin is expressed predominantly in brain where it is enriched on clathrin-coated vesicles. In addition to eight gamma-ear-binding motifs, aftiphilin contains two WXXF-acidic motifs that mediate binding to the alpha-ear of clathrin adaptor protein 2 (AP-2) and three FXXFXXF/L motifs that mediate binding to the alpha- and beta2-ear. We demonstrate that aftiphilin uses these motifs for interactions with AP-1 and AP-2 and that it immunoprecipitates these APs but not AP-3 or AP-4 from brain extracts. Aftiphilin demonstrates a brefeldin A sensitive localization to the trans-Golgi network in hippocampal neurons where it co-localizes with AP-1. Aftiphilin is also found at synapses where it co-localizes with synaptophysin and AP-2. Our data suggest a role for aftiphilin in clathrin-mediated trafficking in neurons.     

Changes in fatty acid composition in Pseudomonas putida and Pseudomonas stutzeri during naphthalene degradation

The effects of naphthalene on the whole cell-derived fatty acid composition of Pseudomonas putida and Pseudomonas stutzeri during naphthalene degradation were investigated. These strains differed in their abilities to degrade naphthalene and in 1,2-catechol dioxygenase activities. The cells of both strains reacted to the addition of naphthalene with an increase in the saturated/unsaturated ratio. The dynamic changes comprised also alterations in the percentage of hydroxy, cyclopropane and branched fatty acids. Upon the exposure of naphthalene, new fatty acids were detected.