Cross-talk between cd1d-restricted nkt cells and γδ cells in t regulatory cell response

CD1d is a non-classical major histocompatibility class 1-like molecule which primarily presents either microbial or endogenous glycolipid antigens to T cells involved in innate immunity. Natural killer T (NKT) cells and a subpopulation of γδ T cells expressing the Vγ4 T cell receptor (TCR) recognize CD1d. NKT and Vγ4 T cells function in the innate immune response via rapid activation subsequent to infection and secrete large quantities of cytokines that both help control infection and modulate the developing adaptive immune response. T regulatory cells represent one cell population impacted by both NKT and Vγ4 T cells. This review discusses the evidence that NKT cells promote T regulatory cell activation both through direct interaction of NKT cell and dendritic cells and through NKT cell secretion of large amounts of TGFβ, IL-10 and IL-2. Recent studies have shown that CD1d-restricted Vγ4 T cells, in contrast to NKT cells, selectively kill T regulatory cells through a caspase-dependent mechanism. Vγ4 T cell elimination of the T regulatory cell population allows activation of autoimmune CD8+ effector cells leading to severe cardiac injury in a coxsackievirus B3 (CVB3) myocarditis model in mice. CD1d-restricted immunity can therefore lead to either immunosuppression or autoimmunity depending upon the type of innate effector dominating during the infection

23-Hydroxybetulinic acid-mediated apoptosis is accompanied by decreases in bcl-2 expression and telomerase activity in HL-60 Cells

23-Hydroxybetulinic acid, a derivative of betulinic acid, was investigated for its apoptotic effect and the associated telomerase activity in human leukemia HL-60 cells. Apoptosis and bcl-2 were determined by flow cytometry analysis. A PCR-based telomeric repeat amplification protocol assay was used to detect telomerase activity. Results showed that 23-hydroxybetulinic acid induced growth arrest and apoptotic cell death in HL-60 cells. The apoptotic events were associated with concurrent down-regulation of bcl-2 and the telomerase activity. Our data suggest that 23-hydroxybetulinic acid may be a potential cytotoxic agent for treatment of cancer. (C) 2002 Elsevier Science Inc. All rights reserved

Three dammarane-type saponins from Gynostemma pentaphyllum

Three new dammarane-type saponins, compounds 1 - 3, were isolated from the aerial parts of Gynostemma pentaphyllum. Their structures were determined using NMR analysis and acid hydrolysis. The structure and stereochemistry of compound 1 were confirmed by X-ray crystallography

Identification of a novel multiple environmental factor-responsive 1-aminocyclopropane-1-carboxylate synthase gene, NT-ACS2, from tobacco

Many abiotic environmental factors elicit the production of stress-ethylene in higher plants. To elucidate the molecular mechanisms underlying the regulation of stress-ethylene production and the physiological roles played by stress-ethylene in stress responses of plants, we studied the gene expression of ACC synthase in tobacco plants that had been subjected to environmental stresses. Four new tobacco ACC synthase cDNA fragments, NT-ACS2, NT-ACS3, NT-ACS4 and NT-ACS5, were identified and sequenced. It was found that NT-ACS2 could be induced by wounding, cold temperature and, especially, sunlight. NT-ACS4 was induced at a faster kinetics by wounding. The multiple environmental stress-responsive (MESR) NT-ACS2 gene was found to contain three introns and four exons and encode a polypeptide of 484 amino acids, 54.6 kDa and pI 6.87. Computer analysis of the 3.4 kb 5' flanking region upstream of the ACS coding region revealed the existence of a group of putative cis-acting regulatory elements potentially conferring wounding, chilling, and UV light inducibility. Phylogenetic analysis of ACC synthase genes of different plant origins indicated that the chill-inducible NT-ACS2 gene is closely related to a chilling-inducible citrus ACS gene

Structure of the Roc–COR domain tandem of C. tepidum, a prokaryotic homologue of the human LRRK2 Parkinson kinase

Ras of complex proteins (Roc) belongs to the superfamily of Ras-related small G-proteins that always occurs in tandem with the C-terminal of Roc (COR) domain. This Roc–COR tandem is found in the bacterial and eukaryotic world. Its most prominent member is the leucine-rich repeat kinase LRRK2, which is mutated and activated in Parkinson patients. Here, we investigated biochemically and structurally the Roco protein from Chlorobium tepidum. We show that Roc is highly homologous to Ras, whereas the COR domain is a dimerisation device. The juxtaposition of the G-domains and mutational analysis suggest that the Roc GTPase reaction is stimulated and/or regulated by dimerisation in a nucleotide-dependent manner. The region most conserved between bacteria and man is the interface between Roc and COR, where single-point Parkinson mutations of the Roc and COR domains are in close proximity. The analogous mutations in C. tepidum Roc–COR decrease the GTPase reaction rate, most likely due to a modification of the interaction between the Roc and COR domains

Enhancement of antibody production by the addition of Coenzyme-Q10

Recently, there has been a growing demand for therapeutic monoclonal antibodies (MAbs) on the global market. Because therapeutic MAbs are more expensive than low-molecular-weight drugs, there have been strong demands to lower their production costs. Therefore, efficient methods to minimize the cost of goods are currently active areas of research. We have screened several enhancers of specific MAb production rate (SPR) using a YB2/0 cell line and found that coenzyme-Q10 (CoQ10) is a promising enhancer candidate. CoQ10 is well known as a strong antioxidant in the respiratory chain and is used for healthcare and other applications. Because CoQ10 is negligibly water soluble, most studies are limited by low concentrations. We added CoQ10 to a culture medium as dispersed nanoparticles at several concentrations (Q-Media) and conducted a fed-batch culture. Although the Q-Media had no effect on cumulative viable cell density, it enhanced SPR by 29%. In addition, the Q-Media had no effect on the binding or cytotoxic activity of MAbs. Q-Media also enhanced SPR with CHO and NS0 cell lines by 30%. These observations suggest that CoQ10 serves as a powerful aid in the production of MAbs by enhancing SPR without changing the characteristics of cell growth, or adversely affecting the quality or biological activity of MAbs