ERK1/2 mediates glucose-regulated POMC gene expression in hypothalamic neurons

Hypothalamic glucose-sensing neurons regulate the expression of genes encoding feeding-related neuropetides POMC, AgRP, and NPY – the key components governing metabolic homeostasis. AMP-activated protein kinase (AMPK) is postulated to be the molecular mediator relaying glucose signals to regulate the expression of these neuropeptides. Whether other signaling mediator(s) plays a role is not clear. In this study, we investigated the role of ERK1/2 using primary hypothalamic neurons as the model system. The primary neurons were differentiated from hypothalamic progenitor cells. The differentiated neurons possessed the characteristic neuronal cell morphology and expressed neuronal post-mitotic markers as well as leptin-regulated orexigenic POMC and anorexigenic AgRP/NPY genes. Treatment of cells with glucose dose-dependently increased POMC and decreased AgRP/NPY expression with a concurrent suppression of AMPK phosphorylation. In addition, glucose treatment dose-dependently increased the ERK1/2 phosphorylation. Blockade of ERK1/2 activity with its specific inhibitor PD98059 partially (approximately 50%) abolished glucose-induced POMC expression, but had little effect on AgRP/NPY expression. Conversely, blockade of AMPK activity with its specific inhibitor produced a partial (approximately 50%) reversion of low-glucose-suppressed POMC expression, but almost completely blunted the low-glucose-induced AgRP/NPY expression. The results indicate that ERK1/2 mediated POMC but not AgRP/NPY expression. Confirming the in vitro findings, i.c.v. administration of PD98059 in rats similarly attenuated glucose-induced POMC expression in the hypothalamus, but again had little effect on AgRP/NPY expression. The results are indicative of a novel role of ERK1/2 in glucose-regulated POMC expression and offer new mechanistic insights into hypothalamic glucose sensing.

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RhoGDIα-dependent balance between RhoA and RhoC is a key regulator of cancer cell tumorigenesis

Molecular Biology of the Cell ◽

10.1091/mbc.e11-01-0020 ◽

2011 ◽

Vol 22 (17) ◽

pp. 3263-3275 ◽

Cited By ~ 23

Author(s):

T. T. Giang Ho ◽

Audrey Stultiens ◽

Johanne Dubail ◽

Charles M. Lapière ◽

Betty V. Nusgens ◽

...

Keyword(s):

Tumor Growth ◽

Cancer Progression ◽

Dynamic Balance ◽

Cellular Functions ◽

Expression Of Genes ◽

Genes Encoding ◽

Interfering Rna

RhoGTPases are key signaling molecules regulating main cellular functions such as migration, proliferation, survival, and gene expression through interactions with various effectors. Within the RhoA-related subclass, RhoA and RhoC contribute to several steps of tumor growth, and the regulation of their expression affects cancer progression. Our aim is to investigate their respective contributions to the acquisition of an invasive phenotype by using models of reduced or forced expression. The silencing of RhoC, but not of RhoA, increased the expression of genes encoding tumor suppressors, such as nonsteroidal anti-inflammatory drug–activated gene 1 (NAG-1), and decreased migration and the anchorage-independent growth in vitro. In vivo, RhoC small interfering RNA (siRhoC) impaired tumor growth. Of interest, the simultaneous knockdown of RhoC and NAG-1 repressed most of the siRhoC-related effects, demonstrating the central role of NAG-1. In addition of being induced by RhoC silencing, NAG-1 was also largely up-regulated in cells overexpressing RhoA. The silencing of RhoGDP dissociation inhibitor α (RhoGDIα) and the overexpression of a RhoA mutant unable to bind RhoGDIα suggested that the effect of RhoC silencing is indirect and results from the up-regulation of the RhoA level through competition for RhoGDIα. This study demonstrates the dynamic balance inside the RhoGTPase network and illustrates its biological relevance in cancer progression.

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Human islet preparations distributed for research exhibit a variety of insulin-secretory profiles

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00437.2014 ◽

2015 ◽

Vol 308 (7) ◽

pp. E592-E602 ◽

Cited By ~ 50

Author(s):

Nora S. Kayton ◽

Gregory Poffenberger ◽

Joseph Henske ◽

Chunhua Dai ◽

Courtney Thompson ◽

...

Keyword(s):

Insulin Secretion ◽

Human Islets ◽

Glucose Sensing ◽

Human Islet ◽

Altered Expression ◽

Expression Of Genes ◽

Genes Encoding ◽

Basal Insulin Secretion ◽

The Many

Human islet research is providing new insights into human islet biology and diabetes, using islets isolated at multiple US centers from donors with varying characteristics. This creates challenges for understanding, interpreting, and integrating research findings from the many laboratories that use these islets. In what is, to our knowledge, the first standardized assessment of human islet preparations from multiple isolation centers, we measured insulin secretion from 202 preparations isolated at 15 centers over 11 years and noted five distinct patterns of insulin secretion. Approximately three quarters were appropriately responsive to stimuli, but one quarter were dysfunctional, with unstable basal insulin secretion and/or an impairment in stimulated insulin secretion. Importantly, the patterns of insulin secretion by responsive human islet preparations (stable Baseline and Fold stimulation of insulin secretion) isolated at different centers were similar and improved slightly over the years studied. When all preparations studied were considered, basal and stimulated insulin secretion did not correlate with isolation center, biological differences of the islet donor, or differences in isolation, such as Cold Ischemia Time. Dysfunctional islet preparations could not be predicted from the information provided by the isolation center and had altered expression of genes encoding components of the glucose-sensing pathway, but not of insulin production or cell death. These results indicate that insulin secretion by most preparations from multiple centers is similar but that in vitro responsiveness of human islets cannot be predicted, necessitating preexperimental human islet assessment. These results should be considered when one is designing, interpreting, and integrating experiments using human islets.

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Role of AMPK in skeletal muscle gene adaptation in relation to exercise

Applied Physiology Nutrition and Metabolism ◽

10.1139/h07-079 ◽

2007 ◽

Vol 32 (5) ◽

pp. 904-911 ◽

Cited By ~ 21

Author(s):

Sebastian B. Jørgensen ◽

Thomas E. Jensen ◽

Erik A. Richter

Keyword(s):

Skeletal Muscle ◽

Exercise Training ◽

Mitochondrial Enzymes ◽

Expression Of Genes ◽

Signalling Molecule ◽

Genes Encoding ◽

Ampk Activity ◽

Muscle Gene ◽

Amp Activated Protein Kinase

The 5′-AMP-activated protein kinase (AMPK) functions as an intracellular fuel sensor that affects metabolism and gene expression. AMPK is activated in skeletal muscle in response to exercise and is therefore believed to be an important signalling molecule in regulating adaptation of skeletal muscle to exercise training. This review first focuses on mechanisms regulating AMPK activity during muscle contraction. We then discuss the role of AMPK in regulating expression of genes encoding various enzymes in muscle in the basal state and in relation to exercise training. Although decreased AMPK activity in muscle causes reduced protein expression of mitochondrial enzymes in the basal state, AMPK does not appear to be indispensable for exercise-training induced increase in mitochondrial enzyme expression.

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It Takes Two to Tango: How a Dysregulation of the Innate Immunity, Coupled With Candida Virulence, Triggers VVC Onset

Frontiers in Microbiology ◽

10.3389/fmicb.2021.692491 ◽

2021 ◽

Vol 12 ◽

Author(s):

Andrea Ardizzoni ◽

Robert T. Wheeler ◽

Eva Pericolini

Keyword(s):

Host Response ◽

Vaginal Microbiome ◽

Host Defenses ◽

Fungal Burden ◽

Tissue Invasion ◽

Expression Of Genes ◽

Vaginal Epithelial Cells ◽

Genes Encoding

Vulvovaginal candidiasis (VVC) is a symptomatic inflammation of the vagina mainly caused by C. albicans. Other species, such as C. parapsilosis, C. glabrata, C. tropicalis, and C. krusei, are mainly associated to the recurrent form of the disease (RVVC), although with a lower frequency. In its yeast form, C. albicans is tolerated by the vaginal epithelium, but switching to the invasive hyphal form, co-regulated with the expression of genes encoding virulence factors such as secreted aspartyl proteases (Sap) and candidalysin, allows for tissue damage. Vaginal epithelial cells play an important role by impairing C. albicans tissue invasion through several mechanisms such as epithelial shedding, secretion of mucin and strong interepithelial cell connections. However, morphotype switching coupled to increasing of the fungal burden can overcome the tolerance threshold and trigger an intense inflammatory response. Pathological inflammation is believed to be facilitated by an altered vaginal microbiome, i.e., Lactobacillus dysbiosis. Notwithstanding the damage caused by the fungus itself, the host response to the fungus plays an important role in the onset of VVC, exacerbating fungal-mediated damage. This response can be triggered by host PRR-fungal PAMP interaction and other more complex mechanisms (i.e., Sap-mediated NLRP3 activation and candidalysin), ultimately leading to strong neutrophil recruitment. However, recruited neutrophils appear to be ineffective at reducing fungal burden and invasion; therefore, they seem to contribute more to the symptoms associated with vaginitis than to protection against the disease. Recently, two aspects of the vulvovaginal environment have been found to associate with VVC and induce neutrophil anergy in vitro: perinuclear anti-neutrophil cytoplasmic antibodies (pANCA) and heparan sulfate. Interestingly, CAGTA antibodies have also been found with higher frequency in VVC as compared to asymptomatic colonized women. This review highlights and discusses recent advances on understanding the VVC pathogenesis mechanisms as well as the role of host defenses during the disease.

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Gh is produced by the testis of Japanese eel and stimulates proliferation of spermatogonia

Reproduction ◽

10.1530/rep-11-0203 ◽

2011 ◽

Vol 142 (6) ◽

pp. 869-877 ◽

Cited By ~ 25

Author(s):

Chiemi Miura ◽

Yosuke Shimizu ◽

Maho Uehara ◽

Yuichi Ozaki ◽

Graham Young ◽

...

Keyword(s):

Steroid Hormones ◽

Germ Cells ◽

Physiological Role ◽

Somatic Growth ◽

Japanese Eel ◽

Expression Of Genes ◽

Genes Encoding

Gh plays important roles in development, somatic growth and gametogenesis in vertebrates. To determine the physiological role of Gh in reproduction in male teleosts, the expression of genes encoding Gh and the two Gh receptors (Ghrs) during spermatogenesis, and the action of Ghin vitrowas examined using the Japanese eel (Anguilla japonica).gh,ghr1andghr2mRNA transcripts were detected in all spermatogenic stages.In situhybridization showed the presence ofghr1andghr2mRNA in the germ cells. Immunohistochemistry using an antiserum against eel Gh indicated that Gh protein was localized to Sertoli cells surrounding the germ cells in early spermatogenesis. Recombinant eel Gh induced spermatogonial proliferation in a testis organ culture system, an effect that was independent from the production of steroid hormones or Igf1. This study identifies a role for eel Gh in the regulation of early spermatogenesis, particularly in the mitotic phase of spermatogenesis, that is not mediated by either steroid hormones or Igf1 production.

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In vivo transcriptome analysis provides insights into host-dependent expression of virulence factors by Yersinia entomophaga MH96, during infection of Galleria mellonella

G3 Genes|Genome|Genetics ◽

10.1093/g3journal/jkaa024 ◽

2020 ◽

Vol 11 (1) ◽

Author(s):

Amber R Paulson ◽

Maureen O’Callaghan ◽

Xue-Xian Zhang ◽

Paul B Rainey ◽

Mark R H Hurst

Keyword(s):

Galleria Mellonella ◽

Functional Enrichment ◽

Natural Environments ◽

Insecticidal Toxin ◽

Heat Stable ◽

Expression Of Genes ◽

Genes Encoding ◽

Cell Densities

Abstract The function of microbes can be inferred from knowledge of genes specifically expressed in natural environments. Here, we report the in vivo transcriptome of the entomopathogenic bacterium Yersinia entomophaga MH96, captured during initial, septicemic, and pre-cadaveric stages of intrahemocoelic infection in Galleria mellonella. A total of 1285 genes were significantly upregulated by MH96 during infection; 829 genes responded to in vivo conditions during at least one stage of infection, 289 responded during two stages of infection, and 167 transcripts responded throughout all three stages of infection compared to in vitro conditions at equivalent cell densities. Genes upregulated during the earliest infection stage included components of the insecticidal toxin complex Yen-TC (chi1, chi2, and yenC1), genes for rearrangement hotspot element containing protein yenC3, cytolethal distending toxin cdtAB, and vegetative insecticidal toxin vip2. Genes more highly expressed throughout the infection cycle included the putative heat-stable enterotoxin yenT and three adhesins (usher-chaperone fimbria, filamentous hemagglutinin, and an AidA-like secreted adhesin). Clustering and functional enrichment of gene expression data also revealed expression of genes encoding type III and VI secretion system-associated effectors. Together these data provide insight into the pathobiology of MH96 and serve as an important resource supporting efforts to identify novel insecticidal agents.

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Non-alcoholic fatty liver disease in mice with hepatocyte-specific deletion of mitochondrial fission factor

Diabetologia ◽

10.1007/s00125-021-05488-2 ◽

2021 ◽

Author(s):

Yukina Takeichi ◽

Takashi Miyazawa ◽

Shohei Sakamoto ◽

Yuki Hanada ◽

Lixiang Wang ◽

...

Keyword(s):

Er Stress ◽

Mitochondrial Dynamics ◽

Mitochondrial Fission ◽

Primary Hepatocytes ◽

Alcoholic Fatty Liver ◽

Expression Of Genes ◽

Specific Deletion

Abstract Aims/hypothesis Mitochondria are highly dynamic organelles continuously undergoing fission and fusion, referred to as mitochondrial dynamics, to adapt to nutritional demands. Evidence suggests that impaired mitochondrial dynamics leads to metabolic abnormalities such as non-alcoholic steatohepatitis (NASH) phenotypes. However, how mitochondrial dynamics are involved in the development of NASH is poorly understood. This study aimed to elucidate the role of mitochondrial fission factor (MFF) in the development of NASH. Methods We created mice with hepatocyte-specific deletion of MFF (MffLiKO). MffLiKO mice fed normal chow diet (NCD) or high-fat diet (HFD) were evaluated for metabolic variables and their livers were examined by histological analysis. To elucidate the mechanism of development of NASH, we examined the expression of genes related to endoplasmic reticulum (ER) stress and lipid metabolism, and the secretion of triacylglycerol (TG) using the liver and primary hepatocytes isolated from MffLiKO and control mice. Results MffLiKO mice showed aberrant mitochondrial morphologies with no obvious NASH phenotypes during NCD, while they developed full-blown NASH phenotypes in response to HFD. Expression of genes related to ER stress was markedly upregulated in the liver from MffLiKO mice. In addition, expression of genes related to hepatic TG secretion was downregulated, with reduced hepatic TG secretion in MffLiKO mice in vivo and in primary cultures of MFF-deficient hepatocytes in vitro. Furthermore, thapsigargin-induced ER stress suppressed TG secretion in primary hepatocytes isolated from control mice. Conclusions/interpretation We demonstrated that ablation of MFF in liver provoked ER stress and reduced hepatic TG secretion in vivo and in vitro. Moreover, MffLiKO mice were more susceptible to HFD-induced NASH phenotype than control mice, partly because of ER stress-induced apoptosis of hepatocytes and suppression of TG secretion from hepatocytes. This study provides evidence for the role of mitochondrial fission in the development of NASH. Graphical abstract

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The Genes Encoding Small Leucine-Rich Proteoglycans Undergo Differential Expression Alterations in Colorectal Cancer, Depending on Tumor Location

Cells ◽

10.3390/cells10082002 ◽

2021 ◽

Vol 10 (8) ◽

pp. 2002

Author(s):

Maria Pilar Solis-Hernandez ◽

Carla Martín ◽

Beatriz García ◽

Natalia Pérez-López ◽

Yolanda García-Mesa ◽

...

Keyword(s):

Protein Expression ◽

Survival Data ◽

Tumor Cell Line ◽

Tumor Location ◽

Anatomical Location ◽

Cell Interior ◽

Expression Of Genes ◽

Genes Encoding ◽

Descending Colon

Small leucine-rich proteoglycans (SLRPs) regulate different processes and undergo significant alterations in various diseases. Colon carcinomas (CCs) are heterogeneous pathologies with important clinical and molecular differences depending on their location, which makes it interesting to analyze the alterations in SLRPs in right- and left-sided tumors (RS- and LSCCs). SLRP transcription levels were studied in 32 CCs using qPCR compared to healthy colon mucosae samples from the same patients, 20 of them from LSCCs and the remaining 12 from RSCCs. Protein expression of genes with significant differences in their transcriptions was analyzed by immunohistochemistry. The alterations observed were related to survival data. The arrangement of transcription of SLRPs was quite similar in ascending and descending colon, but RS- and LSCCs displayed different patterns of alteration, with a greater number of deregulations occurring in the latter. The analysis of protein expression also indicated changes in the location of these molecules, largely moving to the cell interior. While podocan underexpression showed a trend toward better outcomes, no differences were observed in terms of overall survival. In vitro studies using the HT29 tumor cell line suggest that deregulation of SLRPs could affect cell proliferation. SLRPs constitute new differential markers of RS- and LSCCs, showing differences dependent on the anatomical location of the tumor.

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Glucose regulates AMP-activated protein kinase activity and gene expression in clonal, hypothalamic neurons expressing proopiomelanocortin: additive effects of leptin or insulin

Journal of Endocrinology ◽

10.1677/joe-06-0080 ◽

2007 ◽

Vol 192 (3) ◽

pp. 605-614 ◽

Cited By ~ 46

Author(s):

Fang Cai ◽

Armen V Gyulkhandanyan ◽

Michael B Wheeler ◽

Denise D Belsham

Keyword(s):

Protein Kinase ◽

Energy Homeostasis ◽

Cell Model ◽

Neuronal Cell ◽

Cell Types ◽

Glucose Sensing ◽

Protein Kinase Activity ◽

Energy Status ◽

Ampk Activity ◽

Amp Activated Protein Kinase

The mammalian hypothalamus comprises an array of phenotypically distinct cell types that interpret peripheral signals of energy status and, in turn, elicits an appropriate response to maintain energy homeostasis. We used a clonal representative hypothalamic cell model expressing proopiomelanocortin (POMC; N-43/5) to study changes in AMP-activated protein kinase (AMPK) activity and glucose responsiveness. We have demonstrated the presence of cellular machinery responsible for glucose sensing in the cell line, including glucokinase, glucose transporters, and appropriate ion channels. ATP-sensitive potassium channels were functional and responded to glucose. The N-43/5 POMC neurons may therefore be an appropriate cell model to study glucose-sensing mechanisms in the hypothalamus. In N-43/5 POMC neurons, increasing glucose concentrations decreased phospho-AMPK activity. As a relevant downstream effect, we found that POMC transcription increased with 2.8 and 16.7 mM glucose. Upon addition of leptin, with either no glucose or with 5 mM glucose, we found that leptin decreased AMPK activity in N-43/5 POMC neurons, but had no significant effect at 25 mM glucose, whereas insulin decreased AMPK activity at only 5 mM glucose. These results demonstrate that individual hypothalamic neuronal cell types, such as the POMC neuron, can have distinct responses to peripheral signals that relay energy status to the brain, and will therefore be activated uniquely to control neuroendocrine function.

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