Febs Letters

doi: 10.1016/S0014-5793(02)02796-5pmid: N/A

Oshima, Kumi; Ruhul Amin, A.R.M; Suzuki, Atsushi; Hamaguchi, Michinari; Matsuda, Satoru

doi: 10.1016/S0014-5793(02)02703-5pmid: 12023008

Src homology 2 (SH2) domain‐containing protein tyrosine phosphatase substrate 1 (SHPS‐1) is a member of the signal regulatory protein (SIRP) family. The amino‐terminal immunoglobulin‐like domain of SHPS‐1 is necessary for interaction with CD47, a ligand for SHPS‐1, which plays an important role in cell–cell interaction. The intracellular region of SHPS‐1, on the other hand, may act as a scaffold protein, binding to various adapter proteins. Interestingly, increasing evidence has shown that SHPS‐1 is involved in various biological phenomena, including suppression of anchorage‐independent cell growth, negative regulation of immune cells, self‐recognition of red blood cells, mediation of macrophage multinucleation, skeletal muscle differentiation, entrainment of circadian clock, neuronal survival and synaptogenesis. Recent progress has been made in attributing these novel exciting functions. Here we discuss how this interesting molecule works and consider its true role in biology.

Azzi, Angelo; Ricciarelli, Roberta; Zingg, Jean-Marc

doi: 10.1016/S0014-5793(02)02706-0pmid: 12023009

α‐Tocopherol (the major vitamin E component) regulates key cellular events by mechanisms unrelated with its antioxidant function. Inhibition of protein kinase C (PKC) activity and vascular smooth muscle cell growth by α‐tocopherol was first described by our group. Later, α‐tocopherol was shown to inhibit PKC in various cell types with consequent inhibition of aggregation in platelets, of nitric oxide production in endothelial cells and of superoxide production in neutrophils and macrophages. α‐Tocopherol diminishes adhesion molecule, collagenase and scavenger receptor (SR‐A and CD36) expression and increases connective tissue growth factor expression.

Kanda, Daisuke; Takagi, Hitoshi; Toyoda, Mitsuo; Horiguchi, Norio; Nakajima, Hiroaki; Otsuka, Toshiyuki; Mori, Masatomo

doi: 10.1016/S0014-5793(02)02677-7pmid: 12023010

The Fas/Fas ligand interaction plays a crucial role in various liver diseases, and administration of agonistic anti‐Fas antibody to mice causes massive hepatic apoptosis and fulminant hepatic failure. Several growth factors have recently been found to function in preventing apoptosis. In this study, we demonstrated that overexpression of transforming growth factor α (TGFα) has a dramatic protective effect on Fas‐mediated hepatic apoptosis at the biochemical and histological levels. Moreover, 85.7% (six out of seven) of TGFα transgenic mice survived the lethal liver damage, whereas all wild‐type mice died. Expression of Bcl‐xL, an anti‐apoptotic protein, was greatly increased in the transgenic mice. Taken together, our findings suggest that TGFα protects against Fas‐mediated liver apoptosis in vivo and up‐regulation of Bcl‐xL may participate in protective effect of TGFα.

Koteiche, Hanane A; Mchaourab, Hassane S

doi: 10.1016/S0014-5793(02)02688-1pmid: 12023011

The determinants of the oligomeric assembly of Hsp16.5, a small heat‐shock protein (sHSP) from Methanococcus jannaschii, were explored via site‐directed truncation and site‐directed spin labeling. For this purpose, subunit contacts around the two‐, three‐ and four‐fold symmetry axes were fingerprinted using patterns of proximities between nitroxide spin labels introduced at selected sites. The lack of change in this fingerprint in an N‐terminal truncation of the protein demonstrates that the interactions are encoded in the α‐crystallin domain. In contrast, the truncation of the N‐terminal domain of Mycobacterium tuberculosis Hsp16.3, a bacterial sHSP with an equally short N‐terminal region, results in the dissociation of the oligomer to a trimer. These results, in conjunction with those from previous truncation studies in mammalian sHSP, suggest that as the α‐crystallin domain evolved to encode a smaller basic unit than the overall oligomer, the control of the assembly and dynamics of the oligomeric structure became encoded in the N‐terminal domain.

Ostos, Maria A; Recalde, Delia; Zakin, Mario M; Scott-Algara, Daniel

doi: 10.1016/S0014-5793(02)02692-3pmid: 12023012

Atherosclerosis has many features of a chronic inflammatory disease. To evaluate the role of lipopolysaccharide (LPS), mimicking a systemic infection, we administered the endotoxin to apolipoprotein E (apoE)‐deficient mice. LPS injections increase the atherosclerotic lesion size and the titer of plasma autoantibodies directed against oxidized low‐density lipoprotein. We found that Th1 and Th2 T cells help the activation of B cells in the autoimmune response. The number of interleukin‐4 producing natural killer T cells is highly increased in peripheral blood, liver, spleen and thymus cells, as well as in the atherosclerotic plaque of the LPS‐treated mice. Finally, an important adventitial infiltrate of activated lymphocytes, sign of an advanced atherosclerosis, is observed only in the LPS‐treated mice. Our results demonstrate that LPS administration aggravates atherosclerosis in apoE‐deficient mice. LPS‐injected apoE‐deficient mice appear to be an excellent animal model to analyze the implementation of new therapeutic approaches in the treatment of atherosclerosis by manipulating immunological effectors.

Dharmapuri, Sridhar; Rosati, Carlo; Pallara, Patrizia; Aquilani, Riccardo; Bouvier, Florence; Camara, Bilal; Giuliano, Giovanni

doi: 10.1016/S0014-5793(02)02699-6pmid: 12023013

Ripe tomato fruits accumulate significant amounts of the linear carotene lycopene, but only trace amounts of xanthophylls (oxygenated carotenoids). We overexpressed the lycopene β‐cyclase (b‐Lcy) and β‐carotene hydroxylase (b‐Chy) genes under the control of the fruit‐specific Pds promoter. Transgene and protein expression was followed through semi‐quantitative reverse transcription‐PCR, Western blotting, and enzyme assays. Fruits of the transformants showed a significant increase of β‐carotene, β‐cryptoxanthin and zeaxanthin. The carotenoid composition of leaves remained unaltered. The transgenes and the phenotype are inherited in a dominant Mendelian fashion. This is the first example of successful metabolic engineering of xanthophyll content in tomato fruits.

Alam, Mohammad Taufiq; Yamada, Takafumi; Carlsson, Uno; Ikai, Atsushi

doi: 10.1016/S0014-5793(02)02693-5pmid: 12023014

In order to better understand the contribution of the knotted folding pattern to the enzymatic and mechanical properties of carbonic anhydrases, we replaced Gln‐253 of bovine carbonic anhydrase II with Cys, which allowed us to measure the mechanical strength of the protein against tensile deformation by avoiding knot tightening. The expressed protein, to our surprise, turned out to contain two conformational isomers, one capable of binding an enzymatic inhibitor and the other not, which led to their separation through affinity chromatography. In near‐ and far‐UV circular dichroism and fluorescence spectra, the separated conformers were very similar to each other and to the wild‐type enzyme, indicating that they both had native‐like conformations. We describe new evidence which supports the notion that the difference between the two conformers is likely to be related to the completeness of the C‐terminal knot formation.

Lloyd, David; Eshantha, L.; Salgado, J.; Turner, Michael P.; Murray, Douglas B.

doi: 10.1016/S0014-5793(02)02704-7pmid: 12023015

Respiratory oscillations in continuous yeast cultures can be accounted for by cyclic energization of mitochondria, dictated by the demands of a temperature‐compensated ultradian clock with a period of 50 min. Inner mitochondrial membranes show both ultrastructural modifications and electrochemical potential changes. Electron transport components (NADH and cytochromes c and c oxidase) show redox state changes as the organisms cycle between their energized and de‐energized phases. These regular cycles are transiently perturbed by uncouplers of energy conservation, with amplitudes more affected than period; that the characteristic period is restored after only one prolonged cycle, indicates that mitochondrial energy generation is not part of the clock mechanism itself, but is responding to energetic requirement.

Park, Myung-Ae; Lee, Min-Jung; Lee, Sang-Hwa; Jung, Dong-Keun; Kwak, Jong-Young

doi: 10.1016/S0014-5793(02)02705-9pmid: 12023016

Neutrophil apoptosis is a constitutive process that can be enhanced or delayed by signals induced by various stimuli. We investigated the role of phospholipase D (PLD) in neutrophil apoptosis. The apoptotic rate of neutrophils was found to be increased by 1‐butanol and decreased by the exogenous addition of PLD. Moreover, the delay of apoptosis by apoptosis‐delaying stimuli such as granulocyte/macrophage colony‐stimulating factor or lipopolysaccharide (LPS) was also blocked by 1‐butanol. Unstimulated PLD activity in cultured cells for 20 h was higher than that in freshly isolated cells and further increased in cultured cells with LPS. These results suggest that PLD is involved in the up‐regulation of neutrophil survival.