Hepatic stellate cell (vitamin A-storing cell) and its relative--past, present and future

HSCs (hepatic stellate cells) (also called vitamin A-storing cells, lipocytes, interstitial cells, fat-storing cells or Ito cells) exist in the space between parenchymal cells and liver sinusoidal endothelial cells of the hepatic lobule and store 50-80% of vitamin A in the whole body as retinyl palmitate in lipid droplets in the cytoplasm. In physiological conditions, these cells play pivotal roles in the regulation of vitamin A homoeostasis. In pathological conditions, such as hepatic fibrosis or liver cirrhosis, HSCs lose vitamin A and synthesize a large amount of extracellular matrix components including collagen, proteoglycan, glycosaminoglycan and adhesive glycoproteins. Morphology of these cells also changes from the star-shaped SCs (stellate cells) to that of fibroblasts or myofibroblasts. The hepatic SCs are now considered to be targets of therapy of hepatic fibrosis or liver cirrhosis. HSCs are activated by adhering to the parenchymal cells and lose stored vitamin A during hepatic regeneration. Vitamin A-storing cells exist in extrahepatic organs such as the pancreas, lungs, kidneys and intestines. Vitamin A-storing cells in the liver and extrahepatic organs form a cellular system. The research of the vitamin A-storing cells has developed and expanded vigorously. The past, present and future of the research of the vitamin A-storing cells (SCs) will be summarized and discussed in this review.     

Sequential aldol condensation catalyzed by hyperthermophilic 2-deoxy-d-ribose-5-phosphate aldolase

Genes encoding 2-deoxy-d-ribose-5-phosphate aldolase (DERA) homologues from two hyperthermophiles, the archaeon Pyrobaculum aerophilum and the bacterium Thermotoga maritima, were expressed individually in Escherichia coli, after which the structures and activities of the enzymes produced were characterized and compared with those of E. coli DERA. To our surprise, the two hyperthermophilic DERAs showed much greater catalysis of sequential aldol condensation using three acetaldehydes as substrates than the E. coli enzyme, even at a low temperature (25 degrees C), although both enzymes showed much less 2-deoxy-d-ribose-5-phosphate synthetic activity. Both the enzymes were highly resistant to high concentrations of acetaldehyde and retained about 50% of their initial activities after a 20-h exposure to 300 mM acetaldehyde at 25 degrees C, whereas the E. coli DERA was almost completely inactivated after a 2-h exposure under the same conditions. The structure of the P. aerophilum DERA was determined by X-ray crystallography to a resolution of 2.0 A. The main chain coordinate of the P. aerophilum enzyme monomer was quite similar to those of the T. maritima and E. coli enzymes, whose crystal structures have already been solved. However, the quaternary structure of the hyperthermophilic enzymes was totally different from that of the E. coli DERA. The areas of the subunit-subunit interface in the dimer of the hyperthermophilic enzymes are much larger than that of the E. coli enzyme. This promotes the formation of the unique dimeric structure and strengthens the hydrophobic intersubunit interactions. These structural features are considered responsible for the extremely high stability of the hyperthermophilic DERAs.     

Fine mapping and allelic dosage effect of <Emphasis Type="Italic">Hwc1</Emphasis>, a complementary hybrid weakness gene in rice

Hybrid weakness is a reproductive barrier that is found in many plant species. In rice, the hybrid weakness caused by two complementary genes, Hwc1 and Hwc2, has been surveyed intensively. However, their gene products and the molecular mechanism that causes hybrid weakness have remained unknown. We performed linkage analyses of Hwc1, narrowed down the area of interest to 60 kb, and identified eight candidate genes. In the F(2) population, in which both Hwc1 and Hwc2 genes were segregated, plants were separable into four classes according to their respective phenotypes: severe type, semi-severe type, F(1) type, and normal type. Severe type plants show such severe symptoms that they could produce only tiny shoot-like structures; they were unable to generate roots. Genetic analyses using closely linked DNA markers of the two genes showed that the symptoms of the F(2) plants were explainable by the genotypes of Hwc1 and Hwc2. Weakness was observed in plants that have both Hwc1 and Hwc2. In Hwc1 homozygote, the symptoms worsened and severe type or semi-severe type plants appeared. Consequently, Hwc1 should have a gene dosage effect and be a semi-dominant gene. The dosage effect of Hwc2 was recognizable, but it was not so severe as that in Hwc1. These results are useful to elucidate the mechanism that causes the hybrid weakness phenomenon and the role of each causal gene in hybrid weakness.     

Critical role of the Fc receptor gamma-chain on APCs in the development of allergen-induced airway hyperresponsiveness and inflammation

The FcR common gamma-chain (FcRgamma) is an essential component of the receptors FcepsilonRI, FcgammaRI, and FcgammaRIII, which are expressed on many inflammatory cell types. The role of these receptors in the initiation or maintenance of allergic inflammation has not been well defined. FcRgamma-deficient (FcRgamma(-/-)) and control (wild-type (WT)) mice were sensitized and subsequently challenged with OVA. Following sensitization and challenge to OVA, FcRgamma-deficient (FcRgamma(-/-)) mice developed comparable levels of IgE and IgG1 as WT mice. However, numbers of eosinophils, levels of IL-5, IL-13, and eotaxin in bronchoalveolar lavage fluid, and mononuclear cell (MNC) proliferative responses to OVA were significantly reduced, as was airway hyperresponsiveness (AHR) to inhaled methacholine. Reconstitution of FcRgamma(-/-) mice with whole spleen MNC from WT mice before sensitization restored development of AHR and the numbers of eosinophils in bronchoalveolar lavage fluid; reconstitution after sensitization but before OVA challenge only partially restored these responses. These responses were also restored when FcRgamma(-/-) mice received T cell-depleted MNC, T and B cell-depleted MNC, or bone marrow-derived dendritic cells before sensitization from FcR(+/+) or FcgammaRIII-deficient but not FcRgamma(-/-) mice. The expression levels of FcgammaRIV on bone marrow-derived dendritic cells from FcR(+/+) mice were found to be low. These results demonstrate that expression of FcRgamma, most likely FcgammaRI, on APCs is important during the sensitization phase for the development of allergic airway inflammation and AHR.     

Treatment with beta2-adrenoceptor agonist in vivo induces human clock gene, Per1, mRNA expression in peripheral blood

This study examined whether in vivo exposure to a β₂-adrenoceptor agonist, tulobuterol, induces human Period1 (hPer1) mRNA expression in cells from peripheral whole blood. In one experiment, oral tulobuterol was administered to five healthy volunteers at 22:00 h, while in another, a transdermally tulobuterol patch was applied to the same five subjects at 20:00 h. In each experiment, serum tulobuterol concentrations were measured at four time points, and total RNA was isolated from peripheral blood cells for determinations of hPer1 mRNA expression by real-time polymerase chain reaction. Both the tulobuterol tablet and the transdermal patch increased hPer1 mRNA expression, suggesting that analyses of human peripheral blood cells could reliably represent peripheral clock gene mRNA expression in vivo.     

Physical size of the <Emphasis Type="Italic">S</Emphasis> locus region defined by genetic recombination and genome sequencing in <Emphasis Type="Italic">Ipomoea trifida</Emphasis>, Convolvulaceae

Sporophytic self-incompatibility (SSI) in the genus Ipomoea (Convolvulaceae) is controlled by a single polymorphic S locus. We have previously analyzed genomic sequences of an approximately 300 kb region spanning the S locus of the S ₁ haplotype and characterized the genomic structure around this locus. Here, we further define the physical size of the S locus region by mapping recombination breakpoints, based on sequence analysis of PCR fragments amplified from the genomic DNA of recombinants. From the recombination analysis, the S locus of the S ₁ haplotype was delimited to a 0.23 cM region of the linkage map, which corresponds to a maximum physical size of 212 kb. To analyze differences in genomic organization between S haplotypes, fosmid contigs spanning approximately 67 kb of the S ₁₀ haplotype were sequenced. Comparison with the S ₁ genomic sequence revealed that the S haplotype-specific divergent regions (SDRs) spanned 50.7 and 34.5 kb in the S ₁ and S ₁₀ haplotypes, respectively and that their flanking regions showed a high sequence similarity. In the sequenced region of the S ₁₀ haplotype, five of the 12 predicted open reading frames (ORFs) were found to be located in the divergent region and showed co-linear organization of genes between the two S haplotypes. Based on the size of the SDRs, the physical size of the S locus was estimated to fall within the range 34–50 kb in Ipomoea.     

Efficient and rapid purification of drug- and gene-carrying bio-nanocapsules, hepatitis B virus surface antigen L particles, from Saccharomyces cerevisiae

Bio-nanocapsules (BNCs) are hollow particles (approx. 50 nm diameter) consisting of hepatitis B virus surface antigen (HBsAg) large (L, pre-S1+pre-S2+S) proteins embedded in a unilamellar liposome, sharing the same transmembrane S region with an immunogen of hepatitis B vaccine (i.e., HBsAg small (S) protein particle). BNCs can incorporate drugs and genes into the hollow space and systemic administration of the BNCs can deliver the products to human liver via the human hepatocyte-specific receptor within the pre-S (pre-S1+pre-S2) region displayed on BNC's surface. Thus, BNCs are expected to offer efficient and safe non-viral nanocarriers to deliver human liver-specific genes and drugs. To date, BNCs have been purified from the crude extract of BNC-overexpressing yeast cells by fractionation with polyethylene glycol followed by one CsCl equilibrium and two sucrose density gradient ultracentrifugation steps. However, the process was inefficient in terms of yield and time, and was not suitable for mass production because of the ultracentrifugation step. Furthermore, trace contamination with yeast-derived proteinases degraded the pre-S region, which is indispensable for liver-targeting, during long-term storage. In this study, we developed a new purification method involving heat treatment and sulfated cellulofine column chromatography to facilitate rapid purification, completely remove proteinases, and enable mass production. In addition, the BNCs were functional for at least 14 months after lyophilization with 5% (w/v) sucrose as an excipient. This new process will significantly contribute to the development of forthcoming BNC-based nanomedicines as well as hepatitis B vaccines.     

Influences of weight loss on monocytes and T-cell subpopulations in male judo athletes

The purpose of this study was to examine weight loss effects on immune function in judo athletes. Six elite male Japanese judo athletes (20.3 ± 0.4 years) were enrolled in this study. They completed usual weight loss programs during 2 weeks preceding an actual competition. Subjects noted the appearance of upper-respiratory tract infection (URTI) symptoms during the study period. Blood samples were obtained at 40 (baseline period: BL) and 3 (weight loss period: WL) days before and 1 day after the competition (AC). The CD3, CD4, CD8, CD56CD3, CD28CD4, CD28CD8, and Toll-like-receptor-4 (TLR-4) CD14 cells were counted by using flow cytometer analysis. The 6 subjects reported 1 headache, 3 runny nose conditions, and 1 coughing instance during the WL. The CD3, CD4, CD8, and CD28CD4 cell counts were significantly lower at WL than at BL (p ≤ 0.05); they reverted to the baseline value at AC. The TLR-4CD14 cells were significantly fewer at WL (p ≤ 0.05); they remained fewer than they had been at BL, even at AC. These results suggest that 2 weeks of weight loss before a competition can impair cell-mediated immune function and induce high susceptibility to URTI in judo athletes. Coaches, support staff, and athletes should monitor athletes' weight loss, hydration status, appearance of URTI symptoms, and immunocompetence such as lymphocytes and monocytes to prevent the physical condition from becoming worse.