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PubMed2002

Binding of protein kinase B to the plakin family member periplakin.

The serine/threonine kinase protein kinase B (PKB/c-Akt) acts downstream of the lipid kinase phosphoinositide 3-kinase (PI3K) and functions as an essential mediator in many growth-factor-induced cellular responses such as cell cycle regulation, cell survival and transcriptional regulation. PI3K activation generates 3'-phosphorylated phosphatidylinositol lipids (PtdIns3P) and PKB activation requires PtdIns3P-dependent membrane translocation and phosphorylation by upstream kinases. However PKB activation and function is also regulated by interaction with other proteins. Here we show binding of PKB to periplakin, a member of the plakin family of cytolinker proteins. Interaction between PKB and periplakin was mapped to part of the pleckstrin homology (PH) domain of PKB, which is probably not involved in lipid binding, and indeed binding to periplakin did not affect PKB activation. We therefore investigated the possibility that periplakin may act as a scaffold or localization signal for PKB. In cells endogenous periplakin localizes to different cellular compartments, including plasma membrane, intermediate filament structures, the nucleus and mitochondria. Overexpression of the C-terminal part of periplakin, encompassing the PKB binding region, results in predominant intermediate filament localization and little nuclear staining. This also resulted in inhibition of nuclear PKB signalling as indicated by inhibition of PKB-dependent Forkhead transcription factor regulation. These results suggest a possible role for periplakin as a localization signal in PKB-mediated signalling.

3-Phosphoinositide-Dependent Protein Kinases↗

PubMed2003

Regulation of meiotic progression by the meiosis-specific checkpoint kinase Mek1 in fission yeast.

During the eukaryotic cell cycle, accurate transmission of genetic information to progeny is ensured by the operation of cell cycle checkpoints. Checkpoints are regulatory mechanisms that block cell cycle progression when key cellular processes are defective or chromosomes are damaged. During meiosis, genetic recombination between homologous chromosomes is essential for proper chromosome segregation at the first meiotic division. In response to incomplete recombination, the pachytene checkpoint (also known as the meiotic recombination checkpoint) arrests or delays meiotic cell cycle progression, thus preventing the formation of defective gametes. Here, we describe a role for a meiosis-specific kinase, Mek1, in the meiotic recombination checkpoint in fission yeast. Mek1 belongs to the Cds1/Rad53/Chk2 family of kinases containing forkhead-associated domains, which participate in a number of checkpoint responses from yeast to mammals. We show that defects in meiotic recombination generated by the lack of the fission yeast Meu13 protein lead to a delay in entry into meiosis I owing to inhibitory phosphorylation of the cyclin-dependent kinase Cdc2 on tyrosine 15. Mutation of mek1(+) alleviates this checkpoint-induced delay, resulting in the formation of largely inviable meiotic products. Experiments involving ectopic overexpression of the mek1(+) gene indicate that Mek1 inhibits the Cdc25 phosphatase, which is responsible for dephosphorylation of Cdc2 on tyrosine 15. Furthermore, the meiotic recombination checkpoint is impaired in a cdc25 phosphorylation site mutant. Thus, we provide the first evidence of a connection between an effector kinase of the meiotic recombination checkpoint and a crucial cell cycle regulator and present a model for the operation of this meiotic checkpoint in fission yeast.

Amino Acid Sequence↗

PubMed2004

A novel isoform of sarcolemmal membrane-associated protein (SLMAP) is a component of the microtubule organizing centre.

The microtubule organizing centre (MTOC) or the centrosome serves a crucial role in the establishment of cellular polarity, organization of interphase microtubules and the formation of the bipolar mitotic spindle. We have elucidated the genomic structure of a gene encoding the sarcolemmal membrane-associated protein (SLMAP), which encodes a 91 kDa polypeptide with a previously uncharacterized N-terminal sequence encompassing a forkhead-associated (FHA) domain that resides at the centrosome. Anti-peptide antibodies directed against SLMAP N-terminal sequences showed colocalization with gamma-tubulin at the centrosomes at all phases of the cell cycle. Agents that specifically disrupt microtubules did not affect SLMAP association with centrosomes. Furthermore, SLMAP sequences directed a reporter green fluorescent protein (GFP) to the centrosome, and deletions of the newly identified N-terminal sequence from SLMAP prevented the centrosomal targeting. Deletion-mutant analysis concluded that overall, structural determinants in SLMAP were responsible for centrosomal targeting. Elevated levels of centrosomal SLMAP were found to be lethal, whereas mutants that lacked centrosomal targeting inhibited cell growth accompanied by an accumulation of cells at the G2/M phase of the cell cycle.

Amino Acid Sequence↗

PubMed2000

Nuclear and subnuclear targeting sequences of the protein phosphatase-1 regulator NIPP1.

NIPP1 is a nuclear subunit of protein phosphatase-1 (PP1) that colocalizes with pre-mRNA splicing factors in speckles. We report here that the nuclear and subnuclear targeting of NIPP1, when expressed in HeLa cells or COS-1 cells as a fusion protein with the enhanced-green-fluorescent protein (EGFP), are mediated by distinct sequences. While NIPP1-EGFP can cross the nuclear membrane passively, the active transport to the nucleus is mediated by two independent nuclear localization signals in the central domain of NIPP1, which partially overlap with binding site(s) for PP1. Furthermore, the concentration of NIPP1-EGFP in the nuclear speckles requires the 'ForkHead-Associated' domain in the N terminus. This domain is also required for the nuclear retention of NIPP1 when active transport is blocked. Our data imply that the nuclear and subnuclear targeting of NIPP1 are controlled independently.

Amino Acid Sequence↗

PubMed2004

Rapid evolution of muscle fibre number in post-glacial populations of Arctic charr Salvelinus alpinus.

Thingvallavatn, the largest and one of the oldest lakes in Iceland, contains four morphs of Arctic charr Salvelinus alpinus. Dwarf benthic (DB), large benthic (LB), planktivorous (PL) and piscivorous (PI) morphs can be distinguished and differ markedly in head morphology, colouration and maximum fork length (FL(max)), reflecting their different resource specialisations within the lake. The four morphs in Thingvallavatn are thought to have been isolated for approximately 10 000 years, since shortly after the end of the last Ice Age. We tested the null hypothesis that the pattern of muscle fibre recruitment was the same in all morphs, reflecting their recent diversification. The cross-sectional areas of fast and slow muscle fibres were measured at 0.7 FL in 46 DB morphs, 23 LB morphs, 24 PL morphs and 22 PI morphs, and the ages of the charr were estimated using sacculus otoliths. In fish larger than 10 g, the maximum fibre diameter scaled with body mass (M(b))(0.18) for both fibre types in all morphs. The number of myonuclei per cm fibre length increased with fibre diameter, but was similar between morphs. On average, at 60 mum diameter, there were 2264 nuclei cm(-1) in slow fibres and 1126 nuclei cm(-1) in fast fibres. The absence of fibres of diameter 4-10 mum was used to determine the FL at which muscle fibre recruitment stopped. Slow fibre number increased with body length in all morphs, scaling with M(b)(0.45). In contrast, the recruitment of fast muscle fibres continued until a clearly identifiable FL, corresponding to 18-19 cm in the dwarf morph, 24-26 cm in the pelagic morph, 32-33 cm in the large benthic morph and 34-35 cm in the piscivorous morph. The maximum fast fibre number (FN(max)) in the dwarf morph (6.97x10(4)) was 56.5% of that found in the LB and PI morphs combined (1.23x10(5)) (P<0.001). Muscle fibre recruitment continued until a threshold body size and occurred at a range of ages, starting at 4+ years in the DB morph and 7+ years in the LB and PI morphs. Our null hypothesis was therefore rejected for fast muscle and it was concluded that the dwarf condition was associated with a reduction in fibre number. We then investigated whether variations in development temperature associated with different spawning sites and periods were responsible for the observed differences in muscle cellularity between morphs. Embryos from the DB, LB and PL morphs were incubated at temperature regimes simulating cold subterranean spring-fed sites (2.2-3.2 degrees C) and the general lakebed (4-7 degrees C). Myogenic progenitor cells (MPCs) were identified using specific antibodies to Paired box protein 7 (Pax 7), Forkhead box protein K1-alpha (FoxK1-alpha), MyoD and Myf-5. The progeny showed no evidence of developmental plasticity in the numbers of either MPCs or muscle fibres. Juveniles and adult stages of the DB and LB morphs coexist and have a similar diet. We therefore conclude that the reduction in FN(max) in the dwarf morph probably has a genetic basis and that gene networks regulating myotube production are under high selection pressure. To explain these findings we propose that there is an optimal fibre size, and hence number, which varies with maximum body size and reflects a trade-off between diffusional constraints on fibre diameter and the energy costs of maintaining ionic gradients. The predictions of the optimal fibre size hypothesis and its consequences for the adaptive evolution of muscle architecture in fishes are briefly discussed.

Adaptation, Physiological↗

PubMed2005

An updated catalogue of salivary gland transcripts in the adult female mosquito, Anopheles gambiae.

Salivary glands of blood-sucking arthropods contain a variety of compounds that prevent platelet and clotting functions and modify inflammatory and immunological reactions in the vertebrate host. In mosquitoes, only the adult female takes blood meals, while both sexes take sugar meals. With the recent description of the Anopheles gambiae genome, and with a set of approximately 3000 expressed sequence tags from a salivary gland cDNA library from adult female mosquitoes, we attempted a comprehensive description of the salivary transcriptome of this most important vector of malaria transmission. In addition to many transcripts associated with housekeeping functions, we found an active transposable element, a set of Wolbachia-like proteins, several transcription factors, including Forkhead, Hairy and doublesex, extracellular matrix components and 71 genes coding for putative secreted proteins. Fourteen of these 71 proteins had matching Edman degradation sequences obtained from SDS-PAGE experiments. Overall, 33 transcripts are reported for the first time as coding for salivary proteins. The tissue and sex specificity of these protein-coding transcripts were analyzed by RT-PCR and microarray experiments for insight into their possible function. Notably, two gene products appeared to be differentially spliced in the adult female salivary glands, whereas 13 contigs matched predicted intronic regions and may include additional alternatively spliced transcripts. Most An. gambiae salivary proteins represent novel protein families of unknown function, potentially coding for pharmacologically or microbiologically active substances. Supplemental data to this work can be found at http://www.ncbi.nlm.nih.gov/projects/omes/index.html#Ag2.

Amino Acid Sequence↗

PubMed2006

TH2 cells in the pathogenesis of airway remodeling: regulatory T cells a plausible panacea for asthma.

T-helper type 2 (TH2) cells are one of the hallmarks of airway remodeling. The daunting task of regaining tolerance will be to regulate airway hyperresponsiveness (AHR) and remodeling in chronic asthma by balancing the ballet of TH1 and TH2 cells. The mechanism of tolerance appears to be modulated by a specialized subset of T cells called regulatory T cells (Tregs). Currently there are six subtypes of Tregs including CD4+CD25+ naturally occurring (N-Tregs), inducible naïve CD4+CD25- T cells (TR1), TR1 memory phenotype, T-helper type 3 (TH3), CD4-CD25+DX5+ natural killer T cells (TRNKT), and CD4-CD25+CD8+ cytotoxic T cells (TRCTC). The development of Tregs is controversial as to whether they occur in the thymus or peripheral lymphoid tissue. Studies have shown that NTregs are generated in the thymus and TR1 cells occur in the periphery. Nevertheless, Tregs express an arsenal of molecular membrane markers: CD3, CD25, CD62L, CD69, BTLA, GITR, ICOS, Neuroplin- 1 (Nrp-1), and PD-1. However, the most definitive marker is Forkhead Winged-Helix Transcriptional Factor Box p3 (Foxp3). The suppression of N-Tregs occurs by cell-to-cell contact, and low levels of IL-10 and moderate levels of TGF-beta, but the primary mechanism involves the sequestration and activation of neighboring naïve CD4+CD25- T cells to become TR1 cells. In contrast, TR1 cells exert their suppressive properties by copious secretion of IL-10 and TGF- beta. These suppressive mechanisms occur by the inhibition of IL-2 production and the promotion of cell cycle arrest. The development of this specialized subset of T cells is an enigma, but their understanding will provide a plausible panacea for asthma.

Asthma↗

PubMed2004

Aldosterone stimulates gene expression of hepatic gluconeogenic enzymes through the glucocorticoid receptor in a manner independent of the protein kinase B cascade.

Primary aldosteronism is associated with glucose intolerance and diabetes, which is due in part to impaired insulin release caused by reduction of potassium, although other possibilities remain to be elucidated. To evaluate the in vivo effects of aldosterone on glucose metabolism, a single dose of aldosterone was administered to mice, which resulted in elevation of the blood glucose level. In primary cultured mouse hepatocytes, the gene expression of gluconeogenic enzymes such as glucose-6-phosphatase (G6Pase), fructose-1,6-bisphosphatase and phosphoenolpyruvate carboxykinase increased in response to aldosterone in a dose-dependent manner even at a concentration similar to a physiological condition (10(-9) M). The inhibitory effect of insulin on G6Pase gene expression was partially suppressed by aldosterone. Furthermore, aldosterone enhanced G6Pase promoter activity in human hepatoma cell line HepG2, which was prevented by co-treatment with a glucocorticoid antagonist RU-486, but not a mineralocorticoid antagonist spironolactone. In contrast, aldosterone had no effects on major insulin signaling pathways including insulin receptor substrate-1, protein kinase B, and forkhead transcription factor. These results suggest that aldosterone may affect the inhibitory effect of insulin on hepatic gluconeogenesis through the glucocorticoid receptor, which may be one of the causes of impaired glucose metabolism in primary aldosteronism.

Aldosterone↗

PubMed2006

Preconditioning doses of NMDA promote neuroprotection by enhancing neuronal excitability.

Neuroprotection can be induced by low doses of NMDA, which activate both synaptic and extrasynaptic NMDA receptors. This is in apparent contradiction with our recent findings that extrasynaptic NMDA receptor signaling exerts a dominant inhibitory effect on prosurvival signaling from synaptic NMDA receptors. Here we report that exposure to low preconditioning doses of NMDA results in preferential activation of synaptic NMDA receptors because of a dramatic increase in action potential firing. Both acute and long-lasting phases of neuroprotection in the face of apoptotic or excitotoxic insults are dependent on this firing enhancement. Key mediators of synaptic NMDA receptor-dependent neuroprotection, phosphatidylinositol 3 kinase-Akt (PI3 kinase-Akt) signaling to Forkhead box subgroup O (FOXO) export and glycogen synthase kinase 3beta (GSK3beta) inhibition and cAMP response element-binding protein-dependent (CREB-dependent) activation of brain-derived neurotrophic factor (BDNF), can be induced only by low doses of NMDA via this action potential-dependent route. In contrast, NMDA doses on the other side of the toxicity threshold do not favor synaptic NMDA receptor activation because they strongly suppress firing rates below baseline. The classic bell-shaped curve depicting neuronal fate in response to NMDA dose can be viewed as the net effect of two antagonizing (synaptic vs extrasynaptic) curves: via increased firing the synaptic signaling dominates at low doses, whereas firing becomes suppressed and extrasynaptic signaling dominates as the toxicity threshold is crossed.

Action Potentials↗

PubMed2006

The transcription factor six1 inhibits neuronal and promotes hair cell fate in the developing zebrafish (Danio rerio) inner ear.

The developmental processes leading to the differentiation of mechanosensory hair cells and statoacoustic ganglion neurons from the early otic epithelium remain unclear. Possible candidates include members of the Pax-Six-Eya-Dach (paired box-sine oculis homeobox-eyes absent-dachshund) gene regulatory network. We cloned zebrafish six1 and studied its function in inner ear development. Gain- and loss-of-function experiments show that six1 has opposing roles in hair cell and neuronal lineages. It promotes hair cell fate and, conversely, inhibits neuronal fate by differentially affecting cell proliferation and cell death in these lineages. By independently targeting hair cells with atoh1a (atonal homolog 1a) knockdown or neurons with neurog1 (neurogenin 1) knockdown, we showed that the remaining cell population, neurons or hair cells, respectively, is still affected by gain or loss of six1 function. six1 interacts with other members of the Pax-Six-Eya-Dach regulatory network, in particular dacha and dachb in the hair cell but not neuronal lineage. Unlike in mouse, six1 does not appear to be dependent on eya1, although it seems to be important for the regulation of eya1 and pax2b expression in the ventral otic epithelium. Furthermore, six1 expression appears to be regulated by pax2b and also by foxi1 (forkhead box I1) as expected for an early inducer of the otic placode. Our results are the first to demonstrate a dual role for a member of the Pax-Six-Eya-Dach regulatory network in inner ear development.

Animals↗

PubMed2006

Abnormal positioning of diencephalic cell types in neocortical tissue in the dorsal telencephalon of mice lacking functional Gli3.

The transcription factor Gli3 (glioma-associated oncogene homolog) is essential for normal development of the mammalian forebrain. One extreme requirement for Gli3 is at the dorsomedial telencephalon, which does not form in Gli3(Xt/Xt) mutant mice lacking functional Gli3. In this study, we analyzed expression of Gli3 in the wild-type telencephalon and observed a (high)dorsal-to-(low)ventral gradient of Gli3 expression and predominance of the cleaved form of the Gli3 protein dorsally. This graded expression correlates with the (severe)dorsal-to-(mild)ventral telencephalic phenotype observed in Gli3(Xt/Xt) mice. We characterized the abnormal joining of the telencephalon to the diencephalon and defined the medial limit of the dorsal telencephalon in Gli3(Xt/Xt) mice early in corticogenesis. Based on this analysis, we concluded that some of the abnormal expression of ventral telencephalic markers previously described as being in the dorsal telencephalon is, in fact, expression in adjacent diencephalic tissue, which expresses many of the same genes that mark the ventral telencephalon. We observed occasional cells with diencephalic character in the Foxg1 (forkhead box)-expressing Gli3(Xt/Xt) telencephalon at embryonic day 10.5, a day after the anatomical subdivision of the forebrain vesicle. Large clusters of such cells appear in the Gli3(Xt/Xt) neocortical region at later ages, when the neocortex becomes highly disorganized, forming rosettes comprising mainly neural progenitors. We propose that Gli3 is indispensable for formation of an intact telencephalic-diencephalic boundary and for preventing the abnormal positioning of diencephalic cells in the dorsal telencephalon.

Animals↗

PubMed2005

Akt contributes to neuroprotection by hypothermia against cerebral ischemia in rats.

Activation of the Akt/protein kinase B (PKB) kinase pathway can be neuroprotective after stroke. Akt is activated by growth factors via a phosphorylation-dependent pathway involving the kinases phosphoinositide 3 (PI3) kinase and phosphoinositide-dependent protein kinase-1 (PDK1) and is negatively regulated by phosphatase and tensin homolog deleted on chromosome 10 (PTEN). Akt kinase blocks apoptosis by phosphorylating the substrates forkhead transcription factor (FKHR) and glycogen synthase kinase 3beta (GSK3beta). We found that intra-ischemic hypothermia (30 degrees C) reduced infarct size and improved functional outcomes up to 2 months. Changes in phosphorylation levels of Akt, as measured by Western blots and immunostaining, differed from levels of Akt activity measured in an in vitro assay in normothermic animals. Hypothermia blocked most of these changes and maintained Akt activity. Inhibition of PI3/Akt enlarged infarct size in hypothermic animals. Hypothermia improved phosphorylation of PDK1, PTEN, and FKHR. Hypothermia did not improve GSK3beta (Ser9) phosphorylation but blocked the nuclear translocation of phosphorylated beta-catenin (Ser33/37/Thr41) downstream of GSK3beta. Phosphorylation levels of PTEN, Akt, and Akt substrate decreased before apoptotic cytochrome c release and degradation of microtubule-associated protein-2, a marker of neuronal survival. Hypothermia may protect from ischemic damage in part by preserving Akt activity and attenuating the apoptotic effects of PTEN, PDK1, and FKHR.

Animals↗

PubMed1998

The role of Pax3 and Pax7 in development and cancer.

Pax genes consist of a family of transcription factors that are essentially required for the genesis of a variety of tissues and organs. Pax3 and Pax7 are specifically expressed in the dorsal neural tube and the developing somite. Loss-of-function mutations of Pax3 in Splotch mice and in Waardenburg syndrome in man revealed that Pax3 is necessary for the proper formation of caudal neural crest derivatives and for the migration of myoblasts into the limb. Mice with a mutated Pax7 gene suffer from defects in cephalic neural crest derivatives only and indicate that both genes may functionally share some redundancy. Gain-of-function mutations creating fusion proteins consisting of PAX3 or PAX7 and another transcription factor of the forkhead family (FKHR) are associated with alveolar rhabdomyosarcomas. The analyses of Pax3 and Pax7 function in normal development indicate that Pax3 (possibly also Pax7) triggers neoplastic development by maintaining cells in a deregulated undifferentiated and proliferative state in alveolar rhabdomyosarcomas.

Animals↗

PubMed2000

Gene expression of the three members of hepatocyte nuclear factor-3 is differentially regulated by nutritional and hormonal factors.

Hepatocyte nuclear factor-3 (HNF-3) belongs to a large family of forkhead transcription factors and is made up of three members (HNF-3alpha, -3beta and -3gamma). It has been shown that HNF-3 regulates a number of metabolically important genes. However, the mechanisms underlying this regulation of HNF-3 activity by hormones and nutrition have not yet been well elucidated. In attempting to explore the regulation of gene expression of HNF-3 members by physiological status, we analyzed the effects of insulin, dexamethasone and protein malnutrition on the hepatic mRNA level of each member. Male Wistar rats were fed on a 12% casein diet, 12% gluten diet (deficient in lysine and threonine) or a protein-free diet for 1 week. The protein-free diet and gluten diet caused a 3. 7-fold increase in HNF-3g mRNA in the liver and did not affect the mRNA level of either HNF-3alpha or HNF-3beta. Daily administration of dexamethasone caused the mRNA levels of HNF-3alpha and HNF-3beta to increase (2.3- and 1.4-fold, respectively), but had no effect on the HNF-3gamma mRNA level. In diabetic rats that had been injected with streptozotocin, an elevation of the hepatic mRNA levels of HNF-3beta and HNF-3gamma was observed (1.6-and 1.9-fold, respectively). Insulin replacement in the diabetic rats decreased both mRNA levels in a dose-dependent manner. HNF-3alpha mRNA was not affected by insulin status. These results show that the genes of the three members of the HNF-3 family respond differently to hormonal and nutritional factors suggesting that the activities of HNF-3 members are regulated, at least in part, by the levels of their gene expression.

Animals↗

PubMed2005

Ubiquitous and kidney-specific subunits of vacuolar H+-ATPase are differentially expressed during nephrogenesis.

The vacuolar H(+)-ATPase (V-ATPase) is a ubiquitous multisubunit pump that is responsible for acidification of intracellular organelles. In the kidney, a particular form of V-ATPase, made of specific subunits isoforms, has been located at the plasma membrane of intercalated cells (IC). Mutations in genes encoding IC-specific subunits cause infant distal renal tubular acidosis (dRTA), suggesting that the segmental distribution of these subunits is acquired at birth or during early infancy. However, the comparative ontogeny of the IC-specific versus the ubiquitous subunits of V-ATPase and the mechanisms involved in their segmental expression remain unknown. Real-time reverse transcription-PCR, in situ hybridization, immunoblotting, immunostaining, and subcellular fractionation analyses characterized the expression and distribution of V-ATPase subunits, transcription factors, and differentiation markers during mouse nephrogenesis. Ubiquitous A, E1, B2, G1, and C1 subunits showed an early (embryonic day 13.5 [E13.5]) and stable expression throughout nephrogenesis, followed by a slight increase around birth. The developmental pattern of a1 was bimodal, with early induction, gradual decrease during organogenesis, and neonatal increase. These patterns contrasted with the later (from E15.5) and progressive expression of IC-specific a4, B1, G3, and C2 subunits, after the induction of the forkhead transcription factor Foxi1. From E15.5, Foxi1 mRNA was detected in IC, where it co-distributed with B1 in late nephrogenesis. Immunostaining showed that the distribution of ubiquitous E1 and B2 was acquired from E15.5, whereas a4 was located in IC during late nephrogenesis. Subcellular fractionation showed that in both fetal and mature (cortex and medulla) kidneys, E1 and a4 were located in endosomes. These data demonstrate a differential expression and a coordinate regulation of IC-specific versus ubiquitous V-ATPase subunits during nephrogenesis. They provide new insights into the complex regulation of V-ATPase subunits, the maturation of IC along the nephron, and the pathophysiology of hereditary dRTA.

Animals↗

PubMed2025

Mechanism of Qigu capsule as a treatment for sarcopenia based on network pharmacology and experimental validation.

OBJECTIVE: To explore the potential molecular mechanism of Qigu capsule (，QGC) in the treatment of sarcopenia through network pharmacology and to verify it experimentally. METHODS: The active compounds of QGC and common targets between QGC and sarcopenia were screened from databases. Then the herbs-compounds-targets network, and protein-protein interaction (PPI) network was constructed. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed by R software. Next, we used a dexamethasone-induced sarcopenia mouse model to evaluate the anti-sarcopenic mechanism of QGC. RESULTS: A total of 57 common targets of QGC and sarcopenia were obtained. Based on the enrichment analysis of GO and KEGG, we took the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway as a key target to explore the mechanism of QGC on sarcopenia. Animal experiments showed that QGC could increase muscle strength and inhibit muscle fiber atrophy. In the model group, the expression of muscle ring finger-1 and Atrogin-1 were increased, while myosin heavy chain was decreased, QGC treatment reversed these changes. Moreover, compared with the model group, the expressions of p-PI3K, p-Akt, p-mammalian target of rapamycin and p-Forkhead box O3 in the QGC group were all upregulated. CONCLUSION: QGC exerts an anti-sarcopenic effect by activating PI3K/Akt signaling pathway to regulate skeletal muscle protein metabolism.

Sarcopenia↗

PubMed2025

Exploring the therapeutic potential of extract in targeting localized adiposity.

OBJECTIVE: To determine direct targeting of localized adiposity through Morus alba Linne bark injection based on pharmacology network analysis. METHODS: Male C57BL/6J mice were fed a high-fat diet (HFD) to induce obesity. After 6 weeks on HFD, the water extract of Morus alba L.bark (MAB, 2 mg/mL) was locally injected into one inguinal fat pad, while saline was injected into the other side, 3 times/week for 6 weeks (n = 6/group). The water extract of MAB was freeze-dried and then diluted in saline before use. RESULTS: HFD-fed mice treated with local MAB topical injection showed reduced adipocyte weight and size in inguinal fat pads by dual-energy X-ray absorptiometry. No toxicity changes seen in liver, spleen, kidney tissue, or alanine aminotransferase / aspartate aminotransferase levels in serum by MAB injection. Protein levels of phosphorylated insulin receptor substrate-1 and glucose transporter type 4, and mRNA expression of adiponectin, were increased in inguinal adipose tissue injected with MAB locally. Locally MAB injection led to a decrease in glucose-6-phosphatase and phosphoenolpyruvate carboxykinase, linked to gluconeogenesis, while forkhead box protein O1, which regulates these factors, was increased. Moreover, there was an increase in adenosine 5'-monophosphate-activated protein kinase, related to lipogenesis, as well as elevated levels of hormone-sensitive lipase and fatty acid synthase, both associated with lipolysis. These results support the 'insulin signaling pathway' and 'regulation of lipolysis in adipocytes' identified in the Kyoto Encyclopedia of Genes and Genomes pathway through network analysis. CONCLUSION: This study suggests that MAB topical injection exhibits localized fat reduction by inhibiting insulin resistance, gluconeogenesis and lipogenesis mediator, while activating lipolysis enzymes within targeted adipose site.

Animals↗

PubMed2006

Cell Life versus cell longevity: the mysteries surrounding the NAD+ precursor nicotinamide.

Nicotinamide, the amide form of niacin (vitamin B(3)), is the precursor for the coenzyme beta-nicotinamide adenine dinucleotide (NAD(+)) and plays a significant role during the enhancement of cell survival as well as cell longevity. Yet, these abilities of nicotinamide appear to be diametrically opposed. Here we describe the development of nicotinamide as a novel agent that is critical for modulating cellular metabolism, plasticity, longevity, and inflammatory microglial function as well as for influencing cellular life span. The capacity of nicotinamide to govern not only intrinsic cellular integrity, but also extrinsic cellular inflammation rests with the modulation of a host of cellular targets that involve mitochondrial membrane potential, poly(ADP-ribose) polymerase, protein kinase B (Akt), Forkhead transcription factors, Bad, caspases, and microglial activation. Further knowledge acquired in regards to the ability of nicotinamide to foster cellular survival and regulate cellular lifespan should significantly promote the development of therapies against a host of disorders, such as aging, Alzheimer's disease, diabetes, cerebral ischemia, Parkinson's disease, and cancer.

Animals↗