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nutrient sensing

Netra P Meena, Alan R Kimmel
Initial immunological defense mechanisms to pathogen invasion rely on innate pathways of chemotaxis and phagocytosis, original to ancient phagocytes. Although chemotaxis has been well-studied in mammalian and model systems using purified chemoattractants in defined conditions, directed movement toward live bacteria has been more difficult to assess. Dictyostelium discoideum is a professional phagocyte that chemotaxes toward bacteria during growth-phase in a process to locate nutrient sources. Using Dictyostelium as a model, we have developed a system that is able to quantify chemotaxis to very high sensitivity...
2018: Frontiers in Cellular and Infection Microbiology
Soon-Sen Leow, Alice Luu, Swechhya Shrestha, K C Hayes, Ravigadevi Sambanthamurthi
Palm fruit juice (PFJ) containing oil palm phenolics is obtained as a by-product from oil palm (Elaeis guineensis) fruit milling. It contains shikimic acid, soluble fibre and various phenolic acids including p-hydroxybenzoic acid and three caffeoylshikimic acid isomers. PFJ has also demonstrated beneficial health properties in various biological models. Increasing concentrations of PFJ and different PFJ fractions were used to assess growth dynamics and possible anti-ageing properties in fruit flies (Drosophila melanogaster) genotype w1118 ...
March 14, 2018: Experimental Gerontology
M Gómez-Letona, J Arístegui, A G Ramos, M F Montero, J Coca
The eruption of a submarine volcano south of El Hierro Island (Canary Islands) in October 2011 led to major physical and chemical changes in the local environment. Large amounts of nutrients were found at specific depths in the water column above the volcano associated with suboxic layers resulting from the oxidation of reduced chemical species expelled during the eruptive phase. It has been suggested that the fertilization with these compounds enabled the rapid restoration of the ecosystem in the marine reserve south of the island once the volcanic activity ceased, although no biological evidence for this has been provided yet...
March 16, 2018: Scientific Reports
Yilun Deng, Yuejuan Qin, Subramanya Srikantan, Anqi Luo, Zi-Ming Cheng, Shahida K Flores, Kris S Vogel, Exing Wang, Patricia L M Dahia
The TMEM127 tumor suppressor gene encodes a transmembrane protein of unknown function mutated in pheochromocytomas and, rarely, in renal cancers. Tumors with inactivating TMEM127 mutations have increased mTORC1 signaling by undefined mechanisms. Here we report that TMEM127 interacts with the lysosome-anchored complex comprised of Rag GTPases, the LAMTOR pentamer (or 'ragulator') and vATPase, which controls amino acid-mediated mTORC1 activation. We found that in nutrient-rich conditions TMEM127 expression reduces mTORC1 recruitment to Rags...
March 14, 2018: Human Molecular Genetics
Åsa Torinsson Naluai, Ladan Saadat Vafa, Audur H Gudjonsdottir, Henrik Arnell, Lars Browaldh, Staffan Nilsson, Daniel Agardh
BACKGROUND: We have previously performed a Genome Wide Association and linkage study that indicated a new disease triggering mechanism involving amino acid metabolism and nutrient sensing signaling pathways. OBJECTIVE: The aim of this study was to investigate if plasma amino acid levels differed among children with celiac disease compared with disease controls. MATERIALS AND METHODS: Fasting plasma samples from 141 children with celiac disease and 129 non-celiac disease controls, were analyzed for amino acid levels by liquid chromatography-tandem mass spectrometry (LC/MS)...
2018: PloS One
Ariel L Raybuck, Sung Hoon Cho, Jingxin Li, Meredith C Rogers, Keunwook Lee, Christopher L Williams, Mark Shlomchik, James W Thomas, Jin Chen, John V Williams, Mark R Boothby
B lymphocytes migrate among varied microenvironmental niches during diversification, selection, and conversion to memory or Ab-secreting plasma cells. Aspects of the nutrient milieu differ within these lymphoid microenvironments and can influence signaling molecules such as the mechanistic target of rapamycin (mTOR). However, much remains to be elucidated as to the B cell-intrinsic functions of nutrient-sensing signal transducers that modulate B cell differentiation or Ab affinity. We now show that the amino acid-sensing mTOR complex 1 (mTORC1) is vital for induction of Bcl6-a key transcriptional regulator of the germinal center (GC) fate-in activated B lymphocytes...
March 12, 2018: Journal of Immunology: Official Journal of the American Association of Immunologists
Ninon Very, Agata Steenackers, Caroline Dubuquoy, Jeanne Vermuse, Laurent Dubuquoy, Tony Lefebvre, Ikram El Yazidi-Belkoura
The hexosamine biosynthetic pathway (HBP) integrates glucose, amino acids, fatty acids and nucleotides metabolisms for uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) synthesis. UDP-GlcNAc is the nucleotide sugar donor for O-linked β-N-acetylglucosaminylation (O-GlcNAcylation) processes. O-GlcNAc transferase (OGT) is the enzyme which transfers the N-acetylglucosamine (O-GlcNAc) residue onto target proteins. Several studies previously showed that glucose metabolism dysregulations associated with obesity, diabetes or cancer correlated with an increase of OGT expression and global O-GlcNAcylation levels...
March 9, 2018: Journal of Bioenergetics and Biomembranes
Ting Gong, Daniel J Torres, Marla J Berry, Matthew W Pitts
The hypothalamus is the central neural site governing food intake and energy expenditure. During the past 25 years, understanding of the hypothalamic cell types, hormones, and circuitry involved in the regulation of energy metabolism has dramatically increased. It is now well established that the adipocyte-derived hormone, leptin, acts upon two distinct groups of hypothalamic neurons that comprise opposing arms of the central melanocortin system. These two cell populations are anorexigenic neurons expressing proopiomelanocortin (POMC) and orexigenic neurons that express agouti-related peptide (AGRP)...
March 5, 2018: Free Radical Biology & Medicine
Marcus A Gray, Che-Yung Chao, Heidi M Staudacher, Natasha A Kolosky, Nicholas J Talley, Gerald Holtmann
BACKGROUND: In inflammatory bowel disease (IBD), immune activation with increased circulating TNF-α is linked to the intensity of gastrointestinal symptoms and depression or anxiety. A central feature of depression is cognitive biases linked to negative attributions about self, the world and the future. We aimed to assess the effects of anti-TNFα therapy on the central processing of self-attribution biases and visceral afferent information in patients with Crohn's disease. METHODS: We examined 9 patients with Crohn's disease (age 26...
2018: PloS One
Anders Mosbech, Kasper Lambert Johansen, Thomas A Davidson, Martin Appelt, Bjarne Grønnow, Christine Cuyler, Peter Lyngs, Janne Flora
The little auk is the most numerous seabird in the North Atlantic and its most important breeding area is the eastern shores of the North Water polynya. Here, a population of an estimated 33 million pairs breeds in huge colonies and significantly shapes the ecosystem. Archaeological remains in the colonies document that the little auk has been harvested over millennia. Anthropological research discloses how the little auk has a role both as social engineer and as a significant resource for the Inughuit today...
March 7, 2018: Ambio
Gianpiero Vigani, Youry Pii, Silvia Celletti, Mauro Maver, Tanja Mimmo, Stefano Cesco, Stefania Astolfi
Within the last years, extensive information has been accumulated on the reciprocal influence between S and Fe nutrition at both physiological and molecular level in several plant species, but the mechanisms regulating S and Fe sensing and signaling are not fully understood. Fe and S interact for the building of Fe-S clusters, and mitochondria is one of the cellular compartments where Fe-S cluster assembly takes place. Therefore, it would be expected that mitochondria might play a central role in the regulation of Fe and S interaction...
March 2, 2018: Plant Physiology and Biochemistry: PPB
Atsukazu Kuwahara, Yuko Kuwahara, Toshio Inui, Yoshinori Marunaka
The diffuse chemosensory system (DCS) is well developed in the apparatuses of endodermal origin like gastrointestinal (GI) tract. The primary function of the GI tract is the extraction of nutrients from the diet. Therefore, the GI tract must possess an efficient surveillance system that continuously monitors the luminal contents for beneficial or harmful compounds. Recent studies have shown that specialized cells in the intestinal lining can sense changes in the luminal content. The chemosensory cells in the GI tract belong to the DCS which consists of enteroendocrine and related cells...
March 5, 2018: International Journal of Molecular Sciences
Cynthia L Hsu, Elian X Lee, Kara L Gordon, Edwin A Paz, Wen-Chuan Shen, Kohta Ohnishi, Jill Meisenhelder, Tony Hunter, Albert R La Spada
Autophagy is the major cellular pathway by which macromolecules are degraded, and amino acid depletion powerfully activates autophagy. MAP4K3, or germinal-center kinase-like kinase, is required for robust cell growth in response to amino acids, but the basis for MAP4K3 regulation of cellular metabolic disposition remains unknown. Here we identify MAP4K3 as an amino acid-dependent regulator of autophagy through its phosphorylation of transcription factor EB (TFEB), a transcriptional activator of autophagy, and through amino acid starvation-dependent lysosomal localization of MAP4K3...
March 5, 2018: Nature Communications
Chinwendu Nwadike, Leon E Williamson, Laura E Gallagher, Jun-Lin Guan, Edmond Y W Chan
Autophagy maintains metabolism in response to starvation but each nutrient is sensed distinctly. Amino acid deficiency suppresses mechanistic target of rapamycin complex 1 (MTORC1) while glucose deficiency promotes AMP-activated protein kinase (AMPK). MTORC1 and AMPK signalling pathways converge onto the ULK1/2 autophagy initiation complex. Here, we show that amino acid starvation promoted formation of ULK1- and Sequestosome1/p62-positive early autophagosomes. Autophagosome initiation was controlled by MTORC1 sensing glutamine, leucine and arginine levels together...
March 5, 2018: Molecular and Cellular Biology
Ke-Hong Ding, Michael Cain, Michael Davis, Clare Bergson, Meghan McGee-Lawrence, Crystal Perkins, Trevor Hardigan, Xingming Shi, Qing Zhong, Jianrui Xu, Wendy B Bollag, William Hill, Mohammed Elsalanty, Monte Hunter, Maria Isales, Patricia Lopez, Mark Hamrick, Carlos M Isales
Except for the essential amino acids (AAs), much of the focus on adequate dietary protein intake has been on total nitrogen and caloric intake rather than AA composition. Recent data, however, demonstrate that "amino-acid sensing" can occur through either intracellular or extracellular nutrient-sensing mechanisms. In particular, members of the class 3 G-protein coupled receptor family, like the calcium-sensing receptor are known to preferentially bind specific AAs, which then modulate receptor activation by calcium ions and thus potentially impact bone turnover...
February 27, 2018: Bone
Osvaldo Filipe, David De Vleesschauwer, Ashley Haeck, Kristof Demeestere, Monica Höfte
Sucrose non-fermenting-1-related protein kinase-1 (SnRK1) belongs to a family of evolutionary conserved kinases with orthologs in all eukaryotes, ranging from yeasts (SnF1) to mammals (AMP-Activated kinase). These kinases sense energy deficits caused by nutrient limitation or stress and coordinate the required adaptations to maintain energy homeostasis and survival. In plants, SnRK1 is a global regulator of plant metabolism and is also involved in abiotic stress responses. Its role in the response to biotic stress, however, is only starting to be uncovered...
March 1, 2018: Scientific Reports
Ahmed Laamrani, Renato Pardo Lara, Aaron A Berg, Dave Branson, Pamela Joosse
Quantifying the amount of crop residue left in the field after harvest is a key issue for sustainability. Conventional assessment approaches (e.g., line-transect) are labor intensive, time-consuming and costly. Many proximal remote sensing devices and systems have been developed for agricultural applications such as cover crop and residue mapping. For instance, current mobile devices (smartphones & tablets) are usually equipped with digital cameras and global positioning systems and use applications (apps) for in-field data collection and analysis...
February 27, 2018: Sensors
Lisa M Wedding, Joey Lecky, Jamison M Gove, Hilary R Walecka, Mary K Donovan, Gareth J Williams, Jean-Baptiste Jouffray, Larry B Crowder, Ashley Erickson, Kim Falinski, Alan M Friedlander, Carrie V Kappel, John N Kittinger, Kaylyn McCoy, Albert Norström, Magnus Nyström, Kirsten L L Oleson, Kostantinos A Stamoulis, Crow White, Kimberly A Selkoe
A major challenge for coral reef conservation and management is understanding how a wide range of interacting human and natural drivers cumulatively impact and shape these ecosystems. Despite the importance of understanding these interactions, a methodological framework to synthesize spatially explicit data of such drivers is lacking. To fill this gap, we established a transferable data synthesis methodology to integrate spatial data on environmental and anthropogenic drivers of coral reefs, and applied this methodology to a case study location-the Main Hawaiian Islands (MHI)...
2018: PloS One
Federico Pietrocola, Francesca Castoldi, Maria Markaki, Sylvie Lachkar, Guo Chen, David P Enot, Sylvere Durand, Noelie Bossut, Mingming Tong, Shoaib A Malik, Friedemann Loos, Nicolas Dupont, Guillermo Mariño, Nejma Abdelkader, Frank Madeo, Maria Chiara Maiuri, Romano Kroemer, Patrice Codogno, Junichi Sadoshima, Nektarios Tavernarakis, Guido Kroemer
The age-associated deterioration in cellular and organismal functions associates with dysregulation of nutrient-sensing pathways and disabled autophagy. The reactivation of autophagic flux may prevent or ameliorate age-related metabolic dysfunctions. Non-toxic compounds endowed with the capacity to reduce the overall levels of protein acetylation and to induce autophagy have been categorized as caloric restriction mimetics (CRMs). Here, we show that aspirin or its active metabolite salicylate induce autophagy by virtue of their capacity to inhibit the acetyltransferase activity of EP300...
February 27, 2018: Cell Reports
Marie-Anne Deprez, Elja Eskes, Tobias Wilms, Paula Ludovico, Joris Winderickx
The plasma membrane H+ -ATPase Pma1 and the vacuolar V-ATPase act in close harmony to tightly control pH homeostasis, which is essential for a vast number of physiological processes. As these main two regulators of pH are responsive to the nutritional status of the cell, it seems evident that pH homeostasis acts in conjunction with nutrient-induced signalling pathways. Indeed, both PKA and the TORC1-Sch9 axis influence the proton pumping activity of the V-ATPase and possibly also of Pma1. In addition, it recently became clear that the proton acts as a second messenger to signal glucose availability via the V-ATPase to PKA and TORC1-Sch9...
January 12, 2018: Microbial Cell
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