Clenbuterol, a β2-adrenergic agonist, reciprocally alters PGC-1 alpha and RIP140 and reduces fatty acid and pyruvate oxidation in rat skeletal muscle

Clenbuterol, a β2-adrenergic agonist, reduces mitochondrial content and enzyme activities in skeletal muscle, but the mechanism involved has yet to be identified. We examined whether clenbuterol-induced changes in the muscles' metabolic profile and the intrinsic capacity of mitochondria to oxidize substrates are associated with reductions in the nuclear receptor coactivator PGC-1 alpha and/or an increase in the nuclear corepressor RIP140. In rats, clenbuterol was provided in the drinking water (30 mg/l). In 3 wk, this increased body (8%) and muscle weights (12-17%). In red (R) and white (W) muscles, clenbuterol induced reductions in mitochondrial content (citrate synthase: R, 27%; W, 52%; cytochrome-c oxidase: R, 24%; W, 34%), proteins involved in fatty acid transport (fatty acid translocase/CD36: R, 36%; W, 35%) and oxidation [β-hydroxyacyl CoA dehydrogenase (β-HAD): R, 33%; W, 62%], glucose transport (GLUT4: R, 8%; W, 13%), lactate transport monocarboxylate transporter (MCT1: R, 61%; W, 37%), and pyruvate oxidation (PDHE1α, R, 18%; W, 12%). Concurrently, only red muscle lactate dehydrogenase activity (25%) and MCT4 (31%) were increased. Palmitate oxidation was reduced in subsarcolemmal (SS) (R, 30%; W, 52%) and intermyofibrillar (IMF) mitochondria (R, 17%; W, 44%) along with reductions in β-HAD activity (SS: R, 17%; W, 51%; IMF: R, 20%; W, 57%). Pyruvate oxidation was only reduced in SS mitochondria (R, 20%; W, 28%), but this was not attributable solely to PDHE1α, which was reduced in both SS (R, 21%; W, 20%) and IMF mitochondria (R, 15%; W, 43%). These extensive metabolic changes induced by clenbuterol were associated with reductions in PGC-1α (R, 37%; W, 32%) and increases in RIP140 (R, 23%; W, 21%). This is the first evidence that clenbuterol appears to exert its metabolic effects via simultaneous and reciprocal changes in the nuclear receptor coactivator PGC-1α and the nuclear corepressor RIP140.     

W276 mutation in the endothelin receptor subtype B impairs Gq coupling but not Gi or Go coupling

The mutation of W276 to cysteine within the human endothelin receptor subtype B (ET(B)R) is associated with Hirschsprung's disease, a congenital intestinal disease. The sequence surrounding W276 is highly conserved between the endothelin receptor subtypes A and B. We have introduced sets of mutations into W275 and W276 of the ET(B)R gene, and the corresponding W257 and W258 of the ET(A)R gene, and studied their coupling properties with G(i), G(o), and G(q) in reconstituted phospholipid vesicles. The prepared mutants all showed a similar affinity for endothelin-1. The W276C/ET(B)R and W276A/ET(B)R mutants had reduced activities in G(q) coupling but not in G(i)/G(o) coupling, while the W275A/ET(B)R displayed reduced activities in G(i)/G(q) coupling, with normal G(o) coupling. On the other hand, W257A/ET(A)R and W258A/ET(A)R exhibited wild-type activities in all examined G protein couplings. These results suggest that the defects in the G(q) signaling pathway by the ET(B)R are connected with Hirschsprung's disease and that the two conserved tryptophans play distinct roles in signal transduction by the two receptor subtypes. In addition, W275 and W276, which are thought to be located near the extracellular side of the transmembrane helix 5, play important roles in forming the active structure of ET(B)R.     

Book Reviews

Book reviewed in this article:
Behaviour of Teleost Fishes, 2nd edn. Edited by T.J. P itcher
The IUCN Review of the Southern Okavango Integrated Water Development Project by T. S cudder , R.E. M anley , R.W. C olev , R.K. D avis , J. G reen , G.W. H oward , S.W. L awry , D. M artz , P.P. R ogers , A.R.D. T aylor , S.D. T urner , G.F. W hite and E.P. W right     

IDENTIFICATION OF PORPHYRA HAITANENSIS (BANGIALES,RHODOPHYTA) MEIOSIS BY SIMPLE SEQUENCE REPEAT MARKERS1

The simple sequence repeat (SSR) marks were employed to identify the stage at which meiosis occurs in the life cycle of Porphyra haitanensis T. J. Chang et B. F. Zheng. More than 90% of F1 blades of heterozygous conchocelis produced by the cross between a red mutant (R, ♀) and the wildtype (W, ♂) were color sectored. Two parental colors (R and W) and two new colors (R′ and W′) appeared in linear sectors in the color‐sectored F1 blades. Two SSR primer pairs selected from a total of 52 primer pairs generated a specific paternal and maternal fragment, respectively. Co‐occurrence of these two bands was detected in heterozygous conchocelis and in the color‐sectored F1 blades with two to four sectors, such as R + W, R′ + W′, and R′ + R + W + W′. However, the single‐colored F1 blades exhibited only one band. In the sectors isolated from the color‐sectored F1 blades, R and R′ were the same, showing the maternal pattern, whereas W and W′ were the same, showing the paternal pattern. These data suggested that the two different bands from heterozygous conchocelis originated from the parents and segregated in the F1 blades, whereas the two new colors, R′ and W′, in the F1 blades were produced by the exchange and recombination of alleles of the parental colors during meiosis. These results indicated that meiosis of P. haitanensis occurs during the first two cell divisions of a germinating conchospore, and, therefore, the initial four cells constitute a linear genetic tetrad, leading to the formation of a color‐sectored blade.     

Book reviews

THE BIOLOGY OF MOSSES. by D. H. S. R ichardson
PRINCIPLES OF GENETIC MANIPULATION: AN INTRODUCTION TO GENETIC ENGINEERING . By R. W. O ld & S. B. P rimrose Second Edition
HANDBOOK OF PLANT VIRUS INFECTIONS: COMPARATIVE DIAGNOSIS . Edited by E douard K urstak .
CYTOGENETICS . By J urgen S chulz -S chaeffer
PLANT SCIENCE: AN INTRODUCTION TO WORLD CROPS . By J. J anick , R. W. S chery , F. W. W oods , & V. W. R uttan     

STIM1 R304W in mice causes subgingival hair growth and an increased fraction of trabecular bone

Calcium signaling plays a central role in bone development and homeostasis. Store operated calcium entry (SOCE) is an important calcium influx pathway mediated by calcium release activated calcium (CRAC) channels in the plasma membrane. Stromal interaction molecule 1 (STIM1) is an endoplasmic reticulum calcium sensing protein important for SOCE.We generated a mouse model expressing the STIM1 R304W mutation, causing Stormorken syndrome in humans. Stim1^R304W/R304W mice showed perinatal lethality, and the only three animals that survived into adulthood presented with reduced growth, low body weight, and thoracic kyphosis. Radiographs revealed a reduced number of ribs in the Stim1^R304W/R304W mice. Microcomputed tomography data revealed decreased cortical bone thickness and increased trabecular bone volume fraction in Stim1^R304W/R304W mice, which had thinner and more compact bone compared to wild type mice. The Stim1^R304W/+ mice showed an intermediate phenotype. Histological analyses showed that the Stim1^R304W/R304W mice had abnormal bone architecture, with markedly increased number of trabeculae and reduced bone marrow cavity. Homozygous mice showed STIM1 positive osteocytes and osteoblasts. These findings highlight the critical role of the gain-of-function (GoF) STIM1 R304W protein in skeletal development and homeostasis in mice. Furthermore, the novel feature of bilateral subgingival hair growth on the lower incisors in the Stim1^R304W/R304W mice and 25 % of the heterozygous mice indicate that the GoF STIM1 R304W protein also induces an abnormal epithelial cell fate.     

The alpha-L-iduronidase mutations R89Q and R89W result in an attenuated mucopolysaccharidosis type I clinical presentation

Mucopolysaccharidosis type I (MPS I; McKusick 25280; Hurler syndrome, Hurler-Scheie syndrome and Scheie syndrome) is caused by a deficiency in the lysosomal hydrolase, alpha-L-iduronidase (EC 3.2.1.76). MPS I patients present within a clinical spectrum bounded by the extremes of Hurler and Scheie syndromes. The alpha-L-iduronidase missense mutations R89Q and R89W were investigated and altered an important arginine residue proposed to be a nucleophile activator in the catalytic mechanism of alpha-L-iduronidase. The R89Q alpha-L-iduronidase mutation was shown to result in a reduced level of alpha-L-iduronidase protein (< or =10% of normal control) compared to a normal control level of alpha-L-iduronidase protein that was detected for the R89W alpha-L-iduronidase mutation. When taking into account alpha-L-iduronidase specific activity, the R89W mutation had a greater effect on alpha-L-iduronidase activity than the R89Q mutation. However, overall the R89W mutation produced more residual alpha-L-iduronidase activity than the R89Q mutation. This was consistent with MPS I patients, with an R89W allele, having a less severe clinical presentation compared to MPS I patients with either a double or single allelic R89Q mutation. The effects of the R89Q and R89W mutations on enzyme activity supported the proposed role of R89 as a nucleophile activator in the catalytic mechanism of alpha-L-iduronidase.     

Mutant (R406W) human tau is hyperphosphorylated and does not efficiently bind microtubules in a neuronal cortical cell model

Frontotemporal dementia and Parkinsonism linked to chromosome 17 (FTDP-17) is an autosomal dominant neurodegenerative disorder caused by mutations in the gene that encodes for tau, a microtubule-binding protein. Neuropathologically the disease is characterized by extensive neuronal loss in the frontal and temporal lobes and the filamentous accumulation of hyperphosphorylated tau. The R406W missense mutation was originally described in an American and a Dutch family. Although R406W tau is hyperphosphorylated in FTDP-17 cases, R406W tau expressed in cell model systems has not shown increased phosphorylation. The purpose of this study was to establish a neuronal model system in which the phosphorylation of R406W tau is increased and thus more representative of the in vivo situation. To accomplish this goal immortalized mouse cortical cells that express low levels of endogenous tau were stably transfected with human wild type or R406W tau. In this neuronal model R406W tau was more highly phosphorylated at numerous epitopes and showed decreased microtubule binding compared with wild type tau, an effect that could be reversed by dephosphorylation. In addition the expression of R406W tau in the cortical cells resulted in increased cell death as compared with wild type tau-expressing cells when the cells were exposed to an apoptotic stressor. These results indicate that in an appropriate cellular context R406W tau is hyperphosphorylated, which leads to decreased microtubule binding. Furthermore, expression of R406W tau sensitized cells to apoptotic stress, which may contribute to the neuronal cell loss that occurs in this FTDP-17 tauopathy.     

Books

Book reviews in this article:
C ommunication and B ehavior of W hales . R. Payne (ed.).
S trandings : W ays T o S ave W hales . F. D. r obson .
O rders and F amilies of R ecent M ammals of T he W orld . S. Anderson and J. Knox Jones, Jr. (eds.).
S oviet -A merican C ooperative R esearch on M arine M ammals . V olume l—P innipeds . F. H. Fay and G. A. Fedoseev (eds.).
P athobiology of M arine M ammal D iseases . E. B. Howard (ed.).
S eals of T he W orld . (Second Edition.) J. E. Ring. British Museum and Cornell University Press.
T he G ray W hale : E schrichtius R obustus . M. L. Jones, S. L. Swartt and S. Leatherwood.
T he S ierra C lub H andbook of W hales and D olphins . S. Leatherwood and R. R. Reeves.     

LED红、蓝、白组合光对茄子幼苗质量和果皮品质的影响

本试验采用发光二极管(LED)精准调控光源环境,以‘改良大龙茄’为试材,在前期探明红/蓝组合光(R/B)=3/1有利于培育茄子壮苗基础上,以R/B=3/1(9/3,CK₁)和LED白光(W,CK₂)为对照,分别设定LED红蓝白组合光为: R/B/W=3/1/1(9/3/3,T₁)、R/B/W=9/3/8(T₂)、R/B/W=3/1/6(9/3/18,T₃)和R/B/W=3/1/16(9/3/48,T₄),研究其对茄子幼苗生长、根系发育及定植后茄子产量和品质的影响,以期为茄子集约化高效育苗和设施生产补光提供理论依据和技术指导.结果表明: R/B/W=9/3/8组合光处理下,茄子幼苗株高、茎粗、壮苗指数、地上部干重、根干重、根系发育,以及定植后茄皮花青素、类黄酮含量和前期产量均较高;R/B/W=3/1/1组合光处理下,幼苗根冠比、定植后茄皮总酚和果肉中可溶性糖含量较高;而R/B/W=3/1/6组合光处理下,全株叶面积及定植后茄子果肉中游离氨基酸含量较高;R/B/W=3/1/16组合光处理下,定植后茄子果肉中可溶性蛋白含量较高.不同红蓝白组合光可不同程度提高茄子幼苗质量及定植后茄子前期产量和品质,以R/B/W=9/3/8组合光效果最显著.     

A new rhodopsin R135W mutation induces endoplasmic reticulum stress and apoptosis in retinal pigment epithelial cells

Rhodopsin mutations are associated with the autosomal-dominant form of retinitis pigmentosa (RP). Here we report simultaneous occurrence of RP associated with bilateral nanophthalmos and acute angle-closure glaucoma in patient with a new mutation in rhodopsin (R135W). ARPE-19 cells were transfected with myc-tagged wild-type (WT) and R135W rhodopsin constructs. The half-life of WT and R135W rhodopsin was analyzed via cycloheximide chase analysis. We found that R135W rhodopsin was accumulated in the endoplasmic reticulum (ER) and induced unfolded protein response (UPR) and apoptosis. Moreover, chaperone HSP70 alleviated ER stress and prevented apoptosis induced by R135W rhodopsin by attenuating UPR signaling. These findings reveal the novel pathogenic mechanism of RP and suggest that chaperone HSP70 has potential therapeutic significance for RP.     

Analysis of most common mutations R778G, R778L, R778W, I1102T and H1069Q in Indian Wilson disease patients: Correlation between genotype/phenotype/copper ATPase activity

The present study was intented to estimate the frequencies of the most common mutations (R778L, R778W, R778G, I1102T and H1069Q) of ATP7B in Indian Wilson disease (WD) population and to explore the correlation between genotype/phenotype and copper ATPase activity. A total of 33 WD patients and their family members from North West states of India were examined. The H1069Q, R778W and R778L mutations were absent in these WD patients. R778W and I1102T mutations were present in 36% of WD patients. Family analysis for these mutations using PCR-RFLP documented 5 carriers and 2 asymptomatic WD patients. The copper ATPase activity in WD patients was significantly reduced (50%) than that of control individuals. No significant difference was observed in copper stimulated ATPase activity between homozygous (R778W/R778W, I1102T/I1102T) and compound heterozygous (R778W/unknown mutation, I1102T/unknown mutation) WD patients. Serum ceruloplasmin, serum copper levels were significantly lower in homozygous WD patients than that of compound heterozygous. However, no significant difference was observed in liver copper contents between heterozygous and homozygous patients. In conclusion, the data suggest that R778W and I1102T are most common mutations and provide the basis of genetic (PCR-RFLP) diagnostic tool for Indian WD patients as well as in siblings/parents where biochemical parameters are ambiguous.     

An N-ethyl-N-nitrosourea (ENU)-induced dominant negative mutation in the JAK3 kinase protects against cerebral malaria

Cerebral malaria (CM) is a lethal neurological complication of malaria. We implemented a genome-wide screen in mutagenized mice to identify host proteins involved in CM pathogenesis and whose inhibition may be of therapeutic value. One pedigree (P48) segregated a resistance trait whose CM-protective effect was fully penetrant, mapped to chromosome 8, and identified by genome sequencing as homozygosity for a mis-sense mutation (W81R) in the FERM domain of Janus-associated kinase 3 (Jak3). The causative effect of Jak3(W81R) was verified by complementation testing in Jak3(W81R/-) double heterozygotes that were fully protected against CM. Jak3(W81R) homozygotes showed defects in thymic development with depletion of CD8(+) T cell, B cell, and NK cell compartments, and defective T cell-dependent production of IFN-γ. Adoptive transfer of normal splenocytes abrogates CM resistance in Jak3(W81R) homozygotes, an effect attributed to the CD8(+) T cells. Jak3(W81R) behaves as a dominant negative variant, with significant CM resistance of Jak3(W81R/+) heterozygotes, compared to CM-susceptible Jak3(+/+) and Jak3(+/-) controls. CM resistance in Jak3(W81R/+) heterozygotes occurs in presence of normal T, B and NK cell numbers. These findings highlight the pathological role of CD8(+) T cells and Jak3-dependent IFN-γ-mediated Th1 responses in CM pathogenesis.     

Processing and stability of type IIc sodium-dependent phosphate cotransporter mutations in patients with hereditary hypophosphatemic rickets with hypercalciuria

Mutations in the apically located Na(+)-dependent phosphate (NaPi) cotransporter, SLC34A3 (NaPi-IIc), are a cause of hereditary hypophosphatemic rickets with hypercalciuria (HHRH). We have characterized the impact of several HHRH mutations on the processing and stability of human NaPi-IIc. Mutations S138F, G196R, R468W, R564C, and c.228delC in human NaPi-IIc significantly decreased the levels of NaPi cotransport activities in Xenopus oocytes. In S138F and R564C mutant proteins, this reduction is a result of a decrease in the V(max) for P(i), but not the K(m). G196R, R468W, and c.228delC mutants were not localized to oocyte membranes. In opossum kidney (OK) cells, cell surface labeling, microscopic confocal imaging, and pulse-chase experiments showed that G196R and R468W mutations resulted in an absence of cell surface expression owing to endoplasmic reticulum (ER) retention. G196R and R468W mutants could be partially stabilized by low temperature. In blue native-polyacrylamide gel electrophoresis analysis, G196R and R468W mutants were either denatured or present in an aggregation complex. In contrast, S138F and R564C mutants were trafficked to the cell surface, but more rapidly degraded than WT protein. The c.228delC mutant did not affect endogenous NaPi uptake in OK cells. Thus, G196R and R468W mutations cause ER retention, while S138F and R564C mutations stimulate degradation of human NaPi-IIc in renal epithelial cells. Together, these data suggest that the NaPi-IIc mutants in HHRH show defective processing and stability.     

Biochemical and Functional Studies of Lymphoid-Specific Tyrosine Phosphatase (Lyp) Variants S201F and R266W

The Lymphoid specific tyrosine phosphatase (Lyp) has elicited tremendous research interest due to the high risk of its missense mutation R620W in a wide spectrum of autoimmune diseases. While initially characterized as a gain-of-function mutant, R620W was thought to lead to autoimmune diseases through loss-of-function in T cell signaling by a recent study. Here we investigate the biochemical characters and T cell signaling functions of two uncharacterized Lyp variants S201F and R266W, together with a previously characterized Lyp variant R263Q, which had reduced risk in several autoimmune diseases, including systemic lupus erythematosus (SLE), ulcerative colitis (UC) and rheumatoid arthritis (RA). Our kinetic and functional studies of R263Q polymorphism basically reproduced previous findings that it was a loss-of-function mutant. The other variant S201F reduced Lyp phosphatase activity moderately and decreased Lyp function in T cell slightly, while R266W severely impaired phosphatase activity and was a loss-of-function variant in T cell signaling. A combined kinetic and structure analysis suggests that the R266W variant may decrease its phosphatase activity through perturbing either the Q-loop or the WPD loop of Lyp. As both R266W and R263Q significantly change their phosphatase activity and T cell functions, future work could be considered to evaluate these mutants in a broader spectrum of autoimmune diseases.     

Unidirectional incompatibility in Drosophila simulans: inheritance, geographic variation and fitness effects

In California, Drosophila simulans females from some populations (type W) produce relatively few adult progeny when crossed to males from some other populations (type R), but the productivity of the reciprocal cross is comparable to within-population controls. These two incompatibility types are widespread in North America and are also present elsewhere. Both types sometimes occur in the same population. Type R females always produce type R progeny irrespective of the father's type. However, matings between R males and females from stocks classified as type W produce type R progeny at low frequency. This suggests rare paternal transmission of the R incompatibility type, as we have found no evidence for segregation of incompatibility types in the W stocks. There is quantitative variation among type R lines for compatibility with W females, but not vice versa. Population cage studies and productivity tests suggest that deleterious side effects are associated with the type R cytoplasm.     

广东竹亚科新组合及新异名

报道了广东竹亚科13新组合,1新名称和3新异名,其中筋竹属3新组合1新名称,牡竹属4新组合,青篱竹属5组合1新异名,箬竹属2新异名及方竹属1新组合.     

Cation mediation of radical transfer between Trp48 and Tyr356 during O2 activation by protein R2 of Escherichia coli ribonucleotide reductase: relevance to R1-R2 radical transfer in nucleotide reduction?

A tryptophan 48 cation radical (W48(+)(*)) forms concomitantly with the Fe(2)(III/IV) cluster, X, during activation of oxygen for tyrosyl radical (Y122.) production in the R2 subunit of class I ribonucleotide reductase (RNR) from Escherichia coli. W48(+)(*) is also likely to be an intermediate in the long-range radical transfer between R2 and its partner subunit, R1, during nucleotide reduction by the RNR holoenzyme. The kinetics of decay of W48(+)(*) and formation of tyrosyl radicals during O(2) activation (in the absence of R1) in wild-type (wt) R2 and in variants with either Y122, Y356 (the residue thought to propagate the radical from W48(+)(*) into R1 during turnover), or both replaced by phenylalanine (F) have revealed that the presence of divalent cations at concentrations similar to the [Mg(2+)] employed in the standard RNR assay (15 mM) mediates a rapid radical-transfer equilibrium between W48 and Y356. Cation-mediated propagation of the radical from W48 to Y356 gives rise to a fast phase of Y. production that is essentially coincident with W48(+)(*) formation and creates an efficient pathway for decay of W48(+)(*). Possible mechanisms of this cation mediation and its potential relevance to intersubunit radical transfer during nucleotide reduction are considered.     

Books Reviews

Book reviews in this article:
M arine M ammals A shore —A F ield G uide for S trandings .
S tudies of W hite W hales ( D elphinapterus L eucas ) and N arwhals ( M onodon M onoceros ) in G reenland and A djacent Waters. E. W. Born, R. Dietz and R. R. Reeves, eds.
B ooks R eceived
L ife in M oving F luids : The Physical Biology Of Flow. Second Edition.