Branched-chain amino acids regulate type I tropocollagen and type III tropocollagen syntheses via modulation of mTOR in the skin

Abstract

Branched-chain amino acids (BCAAs) exhibit many physiological functions. However, the potential link and mechanism between BCAA and skin function are unknown. We examined the effects of deletion of branched-chain α-keto acid dehydrogenase kinase (BDK), a key enzyme in BCAA catabolism, on type I and III tropocollagen syntheses in mice. Leucine and isoleucine levels were significantly lower in the skin of BDK-KO mice compared with wild-type mice. No changes in valine concentrations were observed. The levels of type I and III tropocollagen proteins and mRNAs (COL1A1 and COL3A1) were significantly lower in the skin of BDK-KO mice compared with wild-type mice. The phosphorylation of p70 S6 kinase, which indicates mammalian target of rapamycin (mTOR) activation, was reduced in the skin of BDK-KO mice compared with wild-type mice. These findings suggest that deficiencies of leucine and isoleucine reduce type I and III tropocollagen syntheses in skin by suppressing the action of mTOR.     

Rapid evaluation of 1-kestose producing β-fructofuranosidases from Aspergillus species and enhancement of 1-kestose production using a PgsA surface-display system

1-Kestose is a key prebiotic fructooligosaccharide (FOS) sugar. Some β-fructofuranosidases (FFases) have high transfructosylation activity, which is useful for manufacturing FOS. Therefore, obtaining FFases that produce 1-kestose efficiently is important. Here, we established a rapid FFase evaluation method using Escherichia coli that display different FFases fused to a PgsA anchor protein from Bacillus subtilis. E. coli cell suspensions expressing the PgsA-FFase fusion efficiently produce FOS from sucrose. Using this screening technique, we found that the E. coli transformant expressing Aspergillus kawachii FFase (AkFFase) produced a larger amount of 1-kestose than those expressing FFases from A. oryzae and A. terreus. Saturation mutagenesis of AkFFase was performed, and the mutant G85W was obtained. The E. coli transformant expressing AkFFase G85W markedly increased production of 1-kestose. Our results indicate that the surface display technique using PgsA is useful for screening of FFases, and AkFFase G85W is likely to be suitable for 1-kestose production.

Abbreviations: AkFFase: Aspergillus kawachii FFase; AoFFase: Aspergillus oryzae FFase; AtFFase: Aspergillus terreus FFase; FFase: β-fructofuranosidase; FOS: fructooligosaccharide; fructosylnystose: 1^F-β-fructofuranosylnystose     

Herpes Simplex Virus 1 VP22 Inhibits AIM2-Dependent Inflammasome Activation to Enable Efficient Viral Replication

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Does Decrease in Ribulose-1,5-Bisphosphate Carboxylase by Antisense RbcS Lead to a Higher N-Use Efficiency of Photosynthesis under Conditions of Saturating CO2 and Light in Rice Plants?

Rice (Oryza sativa L.) plants with decreased ribulose-1,5-bisphosphate carboxylase (Rubisco) were obtained by transformation with the rice rbcS antisense gene under the control of the rice rbcS promoter. The primary transformants were screened for the Rubisco to leaf N ratio, and the transformant with 65% wild-type Rubisco was selected as a plant set with optimal Rubisco content at saturating CO2 partial pressures for photosynthesis under conditions of high irradiance and 25[deg]C. This optimal Rubisco content was estimated from the amounts and kinetic constants of Rubisco and the gas-exchange data. The R1 selfed progeny of the selected transformant were grown hydroponically with different N concentrations. Rubisco content in the R1 population was distributed into two groups: 56 plants had about 65% wild-type Rubisco, whereas 23 plants were very similar to the wild type. Although the plants with decreased Rubisco showed 20% lower rates of light-saturated photosynthesis in normal air (36 Pa CO2), they had 5 to 15% higher rates of photosynthesis in elevated partial pressures of CO2, (100-115 Pa CO2) than the wild-type plants for a given leaf N content. We conclude that the rice plants with 65% wild-type Rubisco show a higher N-use efficiency of photosynthesis under conditions of saturating CO2 and high irradiance.     

Photoconversion of a Water-Soluble Chlorophyll Protein from Chenopodium Album: Resonance Raman and Fourier Transform Infrared Study of Protein and Pigment Structures

A water-soluble Chl a/b-protein complex, CP668, from Chenopodiumalbum converts to another form of protein complex, CP743, uponlight illumination. Structural changes of pigments and proteinsupon photoconversion were studied using resonance Raman (RR)and Fourier transform infrared (FTIR) spectroscopies. RR spectraof CP668 and CP743 and a light-induced FTIR difference spectrumshowed that the macrocyle C=C bands of Chl a in CP668 considerablychanged upon conversion to the pigment (not chemically identifiedyet) in CP743. The C=C band pattern of the RR spectrum of CP743was similar to that of bacteriochlorophyll a, suggesting thatthe conjugated system of the CP743 pigment resembles a bacteriochlorinring. Judging from the C=O frequencies, the 13¹-keto C=O groupsof Chl a and b in CP668 are free from hydrogen bonding, whereasthe 13²-ester C=O groups of both Chl a and b and the 7-formylC=O of Chl b in CP668 are hydrogen bonded. Upon conversion toCP743, interactions of the 13¹-keto and 13²-ester C=O groupswere basically unaffected, demonstrating no drastic changesaround these C=O groups. FTIR spectra in the amide I' regionof CP668 and CP743 in D₂O buffer showed a peak at 1,633 cm^–1,which represents a major component of ß-sheet conformation.Second-derivative spectra of the amide I' bands as well as alight-induced FTIR difference spectrum suggested that drasticchange in the protein conformation does not occur upon photoconversion. (Received November 1, 1998; Accepted December 24, 1998)     

Enhancement of oxidative stress-induced apoptosis by Hsp105alpha in mouse embryonal F9 cells.

Hsp105alpha is one of the major mammalian heat shock proteins that belongs to the HSP105/110 family, and is expressed at especially high levels in the brain as compared with other tissues in mammals. Previously, we showed that Hsp105alpha prevents stress-induced apoptosis in neuronal PC12 cells, and is a novel anti-apoptotic neuroprotective factor in the mammalian brain. On the other hand, we have also demonstrated that Hsp105alpha is expressed transiently at high levels during mouse embryogenesis and is found not only in various tissues but also in apoptotic cells. In the present study, to elucidate the role of Hsp105alpha during mouse embryogenesis, we established mouse embryonal F9 cell lines that constitutively over-express Hsp105alpha. Over-expression of Hsp105alpha enhanced hydrogen peroxide-induced apoptosis by enhancing the activation of caspase-3, poly(ADP-ribose)polymerase cleavage, cytochrome c release and activation of p38 mitogen-activated protein kinase (p38). Furthermore, oxidative stress-induced apoptosis was suppressed by SB202190, a potent inhibitor of p38, in F9 cells. These findings indicated that the activation of p38 is an essential step for apoptosis in F9 cells and that Hsp105alpha enhances activation of p38, release of cytochrome c and caspase activation. Hsp105alpha may play important roles in organogenesis, during which marked apoptosis occurs, by enhancing apoptosis during mouse embryogenesis.     

Ent-labdane-type diterpene glucosides from leaves of Rubus chingii

Previously, a sweet steviol bisglucoside named rubusoside was isolated from leaves of a Chinese Rubus spp. which was tentatively assigned as R. chingii. From leaves of Japanese Rubus chingii (Japanese name Gosho-Ichigo) which are not sweet, five ent-labdane-type diterpene glucosides named goshonosidies F1-5 were isolated instead of rubusoside and their structures were elucidated. The name ‘R. suavissimus’ has been proposed for the Chinese plant.     

Pranidipine,a new 1, 4-dihydropyridine calcium channel blocker,enhances cyclic GMP-independent nitric oxide-induced relaxation of the rat aorta

Pranidipine, a new calcium channel modulator, prolonged endothelium-dependent relaxation induced by acetylcholine in a aortic ring preparation, contracted with prostaglandin F2. This action was not shared by amlodipine. The effect was not modified by indomethacin, suggesting that the action of pranidipine does not involve prostanoid metabolism. N^G-nitro-L-arginine completely prevented the action of Pranidipine. The drug affected neither nitric oxide (NO) synthase activity nor the level of cyclic GMP in the vessel. Pranidipine did not affect the sensitivity of the contractile proteins to calcium. Pranidipine also did not alter cyclic GMP-induced relaxation in a-toxinskinned vascular preparations. Pranidipine also prolonged glyceryl trinitrate-induced relaxation in the endothelium denuded rat aorta. Furthermore, pranidipine enhanced relaxation of the aorta induced by glyceryl trinitrate even in the presence of methylene blue, a guanylyl cyclase inhibitor. This action was not modified by iberiotoxin or by charybdotoxin, two inhibitors of the calciumactivated potassium channel. The results strongly suggest that pranidipine enhances cyclic GMPindependent NO-induced relaxation of smooth muscle by a mechanism other than through NOinduced hyperpolarization. These effects were in direct contrast to amlodipine, another new 1,4dihydropyridine calcium antagonist.     

Analysis of HLA-DQ α sequences for prenatal diagnosis in single fetal cells from maternal blood

We have extended a previously developed method that allows prenatal DNA diagnosis of female fetuses through the isolation of single nucleated erythrocytes from maternal blood by developing a method that can distinguish between maternal and fetal nucleated erythrocytes. Nucleated erythrocytes were separated by a density-gradient method and then collected by micromanipulation. Sex was determined after primer extension preamplification (PEP) of the entire genome of a single cell, and human leukocyte antigen (HLA)-DQ α type was determined after further amplification of this gene. The HLA-DQ α genotype of fetal erythrocytes in maternal blood samples and their corresponding paternal and maternal lymphocytes were successfully determined in all cases. The accuracy of the method was determined by using single nucleated erythrocytes from umbilical cord blood from five normal deliveries. This is the first demonstration that the fetal HLA-DQ α gene sequences can be identified in a small aliquot of a single nucleated erythrocyte in maternal blood. We believe that this method ushers in a new era in which the reliability and accuracy of noninvasive prenatal DNA diagnosis from maternal blood is markedly improved. Received: 18 April 1997 / Accepted: 1 October 1997