Nutrient sensing

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Nutrient sensing is a cell's ability to recognize and respond to fuel substrates such as glucose. Each type of fuel used by the cell requires an alternate pathway of utilization and accessory molecules such as enzymes and cofactors. In order to conserve resources a cell will only produce molecules that it needs at the time. The level and type of fuel that is available to a cell will determine the type of enzymes it needs to express from its genome for utilization. Receptors on the cell membrane's surface designed to be activated in the presence of specific fuel molecules communicate to the cell nucleus via a means of cascading interactions. Nutrient receptors are receptors that are primarily designed to perform the function of nutrient sensing, whereas other receptors (e.g. insulin receptors, leptin receptors) are extensively multifunctional and perform many functions besides nutrient sensing. [1] In this way the cell is aware of the available nutrients and is able to produce only the molecules specific to that nutrient type.

Contents

Nutrient sensing in nammalian cells

A rapid and efficient response to disturbances in nutrient levels is crucial for the survival of organisms from bacteria to humans. Cells have therefore evolved a host of molecular pathways that can sense nutrient concentrations and quickly regulate gene expression and protein modification to respond to any changes. [2]

Cell growth is regulated by coordination of both extracellular nutrients and intracellular metabolite concentrations. AMP-activated kinase (AMPK) and mammalian target of rapamycin complex 1 serve as key molecules that sense cellular energy and nutrients levels, respectively.

Living cells use ATP as the most important direct energy source. Hydrolysis of ATP to ADP and phosphate (or AMP and pyrophosphate) provides energy for most biological processes. The ratio of ATP to ADP and AMP is a barometer of cellular energy status and is therefore tightly monitored by the cell. In eukaryotic cells, AMPK serves as a key cellular energy sensor and a master regulator of metabolism to maintain energy homeostasis. [4]

Nutrient sensing and epigenetics

Nutrient sensing and signaling is a key regulator of epigenetic machinery in cancer. During glucose shortage, the energy sensor AMPK activates arginine methyltransferase CARM1 and mediates histone H3 hypermethylation (H3R17me2), leading to enhanced autophagy. In addition, O-GlcNAc transferase (OGT) signals glucose availability to TET3 and inhibits TET3 by both decreasing its dioxygenase activity and promoting its nuclear export. OGT is also known to directly modify histones with O-GlcNAc. These observations strongly suggest that nutrient signaling directly targets epigenetic enzymes to control epigenetic modifications. [5]

Regulation of tissue growth

Nutrient sensing is a key regulator of tissue growth. The main mediator of cellular nutrient sensing is the protein kinase TOR (target of rapamycin). TOR receives information from levels of cellular amino acids and energy, and it regulates the activity of processes involved in cell growth, such as protein synthesis and autophagy. Insulin-like signaling is the main mechanism of systemic nutrient sensing and mediates its growth-regulatory functions largely through the protein kinase pathway. Other nutrition-regulated hormonal mechanisms contribute to growth control of modulating the activity of insulin-like signaling. [6]

Nutrient sensing in plants

Higher plants require a number of essential nutrient elements for completing their life cycles. Mineral nutrients are mainly acquired by roots from the rhizosphere and are subsequently distributed to shoots. To overcome with nutrient limitations, plants have evolved a set of elaborate responses consisting of sensing mechanisms and signaling processes to perceive and adapt to external nutrient availability. [7]

Plants obtain most necessary nutrients by taking them up from the soil into their roots. Although plants cannot move to a new environment when nutrient availability is less than favorable, they can modify their development to favor root colonization of soil areas where nutrients are abundant. Therefore, plants perceive the availability of external nutrients, like nitrogen, and couple this nutrient sensing to an appropriate adaptive response.

Types of nutrients in plants

Potassium (K+) and phosphorus (P+) are important macronutrients for crops but are often deficient in the field. Very little is known about how plants sense fluctuations in concentrations of K+ and P+, and how such sensing is integrated at the organismic level into physiological and metabolic adaptations. [8] [9] Smaller amounts of other micronutrients are also important for the growth of the crop. All of these nutrients are equally important for the growth of the plant and lack of one nutrient can result in poor growth of the plant as well as becoming more vulnerable to diseases or can lead to death. [10] These nutrients along with CO2 and energy from the sun aids in the development of the plant. [11] [ dead link ]

Nitrogen sensing

As one of the most vital nutrients for the development and growth of all plants, nitrogen sensing and the signalling response are vital for plants to live. [12] Plants absorb nitrogen through the soil in the form of either nitrate or ammonia. [13] In soil with low oxygen levels, ammonia is the primary nitrogen source, but toxicity is carefully controlled for with the transcription of ammonium transporters (AMTs). [13] This metabolite and others including glutamate and glutamine have been shown to act as a signal of low nitrogen through regulation of nitrogen transporter gene transcription. [14] NRT1.1, also known as CHL1, is the nitrate transceptor (transporter and receptor) found on the plasma membrane of plants. [13] This is both a high and low affinity transceptor that senses varying concentrations of nitrate depending on its T101 residue phosphorylation. [13] It has been shown that nitrate can also act as just a signal for plants, since mutants unable to metabolize are still able to sense the ion. [14] For example, many plants show the increase of nitrate-regulated genes in low nitrate conditions and consistent mRNA transcription of such genes in soil high in nitrate. [14] This demonstrates the ability to sense nitrate soil concentrations without metabolic products of nitrate and still exhibit downstream genetic effects. [14]

Potassium Sensing

Potassium (K+), one of the essential macronutrients is found in plant soil. K+ is the most abundant cation and it is very limited in plant soil. Plants absorb K+ from the soil through channels that are found at the plasma membrane of root cells. Potassium is not assimilated into organic matter like other nutrients such as nitrate and ammonium but serves as a major osmoticum. [7]

Brain and gut regulation of food intake

Maintaining a careful balance between stored energy and caloric intake is important to ensure that the body has enough energy to maintain itself, grow, and engage in activity. When balanced improperly, obesity and its accompanying disorders can result. [15]

Related Research Articles

<span class="mw-page-title-main">Hormone</span> Biological signalling molecule

A hormone is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required for the correct development of animals, plants and fungi. Due to the broad definition of a hormone, numerous kinds of molecules can be classified as hormones. Among the substances that can be considered hormones, are eicosanoids, steroids, amino acid derivatives, protein or peptides, and gases.

<span class="mw-page-title-main">Signal transduction</span> Cascade of intracellular and molecular events for transmission/amplification of signals

Signal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events. Most commonly, protein phosphorylation is catalyzed by protein kinases, ultimately resulting in a cellular response. Proteins responsible for detecting stimuli are generally termed receptors, although in some cases the term sensor is used. The changes elicited by ligand binding in a receptor give rise to a biochemical cascade, which is a chain of biochemical events known as a signaling pathway.

In cellular biology, active transport is the movement of molecules or ions across a cell membrane from a region of lower concentration to a region of higher concentration—against the concentration gradient. Active transport requires cellular energy to achieve this movement. There are two types of active transport: primary active transport that uses adenosine triphosphate (ATP), and secondary active transport that uses an electrochemical gradient. This process is in contrast to passive transport, which allows molecules or ions to move down their concentration gradient, from an area of high concentration to an area of low concentration, without energy.

<span class="mw-page-title-main">Plant nutrition</span> Study of the chemical elements and compounds necessary for normal plant life

Plant nutrition is the study of the chemical elements and compounds necessary for plant growth and reproduction, plant metabolism and their external supply. In its absence the plant is unable to complete a normal life cycle, or that the element is part of some essential plant constituent or metabolite. This is in accordance with Justus von Liebig’s law of the minimum. The total essential plant nutrients include seventeen different elements: carbon, oxygen and hydrogen which are absorbed from the air, whereas other nutrients including nitrogen are typically obtained from the soil.

<span class="mw-page-title-main">Glucokinase</span> Enzyme participating to the regulation of carbohydrate metabolism

Glucokinase is an enzyme that facilitates phosphorylation of glucose to glucose-6-phosphate. Glucokinase occurs in cells in the liver and pancreas of humans and most other vertebrates. In each of these organs it plays an important role in the regulation of carbohydrate metabolism by acting as a glucose sensor, triggering shifts in metabolism or cell function in response to rising or falling levels of glucose, such as occur after a meal or when fasting. Mutations of the gene for this enzyme can cause unusual forms of diabetes or hypoglycemia.

A hormone receptor is a receptor molecule that binds to a specific hormone. Hormone receptors are a wide family of proteins made up of receptors for thyroid and steroid hormones, retinoids and Vitamin D, and a variety of other receptors for various ligands, such as fatty acids and prostaglandins. Hormone receptors are of mainly two classes. Receptors for peptide hormones tend to be cell surface receptors built into the plasma membrane of cells and are thus referred to as trans membrane receptors. An example of this is Actrapid. Receptors for steroid hormones are usually found within the protoplasm and are referred to as intracellular or nuclear receptors, such as testosterone. Upon hormone binding, the receptor can initiate multiple signaling pathways, which ultimately leads to changes in the behavior of the target cells.

<span class="mw-page-title-main">Heterocyst</span>

Heterocysts or heterocytes are specialized nitrogen-fixing cells formed during nitrogen starvation by some filamentous cyanobacteria, such as Nostoc, Cylindrospermum, and Anabaena. They fix nitrogen from dinitrogen (N2) in the air using the enzyme nitrogenase, in order to provide the cells in the filament with nitrogen for biosynthesis.

In biochemistry, in the biological context of organisms' regulation of gene expression and production of gene products, downregulation is the process by which a cell decreases the production and quantities of its cellular components, such as RNA and proteins, in response to an external stimulus. The complementary process that involves increase in quantities of cellular components is called upregulation.

<i>N</i>-Acyl homoserine lactone Class of chemical compounds

N-Acyl homoserine lactones are a class of signaling molecules involved in bacterial quorum sensing, a means of communication between bacteria enabling behaviors based on population density.

<span class="mw-page-title-main">Nucleoside-diphosphate kinase</span> Class of enzymes

Nucleoside-diphosphate kinases are enzymes that catalyze the exchange of terminal phosphate between different nucleoside diphosphates (NDP) and triphosphates (NTP) in a reversible manner to produce nucleotide triphosphates. Many NDP serve as acceptor while NTP are donors of phosphate group. The general reaction via ping-pong mechanism is as follows: XDP + YTP ←→ XTP + YDP. NDPK activities maintain an equilibrium between the concentrations of different nucleoside triphosphates such as, for example, when guanosine triphosphate (GTP) produced in the citric acid (Krebs) cycle is converted to adenosine triphosphate (ATP). Other activities include cell proliferation, differentiation and development, signal transduction, G protein-coupled receptor, endocytosis, and gene expression.

Glucose transporter type 4 (GLUT4), also known as solute carrier family 2, facilitated glucose transporter member 4, is a protein encoded, in humans, by the SLC2A4 gene. GLUT4 is the insulin-regulated glucose transporter found primarily in adipose tissues and striated muscle. The first evidence for this distinct glucose transport protein was provided by David James in 1988. The gene that encodes GLUT4 was cloned and mapped in 1989.

<span class="mw-page-title-main">Receptor tyrosine kinase</span> Class of enzymes

Receptor tyrosine kinases (RTKs) are the high-affinity cell surface receptors for many polypeptide growth factors, cytokines, and hormones. Of the 90 unique tyrosine kinase genes identified in the human genome, 58 encode receptor tyrosine kinase proteins. Receptor tyrosine kinases have been shown not only to be key regulators of normal cellular processes but also to have a critical role in the development and progression of many types of cancer. Mutations in receptor tyrosine kinases lead to activation of a series of signalling cascades which have numerous effects on protein expression. Receptor tyrosine kinases are part of the larger family of protein tyrosine kinases, encompassing the receptor tyrosine kinase proteins which contain a transmembrane domain, as well as the non-receptor tyrosine kinases which do not possess transmembrane domains.

Nesfatin-1 is a neuropeptide produced in the hypothalamus of mammals. It participates in the regulation of hunger and fat storage. Increased nesfatin-1 in the hypothalamus contributes to diminished hunger, a 'sense of fullness', and a potential loss of body fat and weight.

<span class="mw-page-title-main">NUAK1</span> Protein-coding gene in the species Homo sapiens

NUAK family SNF1-like kinase 1 also known as AMPK-related protein kinase 5 (ARK5) is an enzyme that in humans is encoded by the NUAK1 gene.

The insulin transduction pathway is a biochemical pathway by which insulin increases the uptake of glucose into fat and muscle cells and reduces the synthesis of glucose in the liver and hence is involved in maintaining glucose homeostasis. This pathway is also influenced by fed versus fasting states, stress levels, and a variety of other hormones.

Nitrogen nutrition in the arbuscular mycorrhizal system refers to...

mTORC1 Protein complex

mTORC1, also known as mammalian target of rapamycin complex 1 or mechanistic target of rapamycin complex 1, is a protein complex that functions as a nutrient/energy/redox sensor and controls protein synthesis.

<i>O</i>-GlcNAc

O-GlcNAc is a reversible enzymatic post-translational modification that is found on serine and threonine residues of nucleocytoplasmic proteins. The modification is characterized by a β-glycosidic bond between the hydroxyl group of serine or threonine side chains and N-acetylglucosamine (GlcNAc). O-GlcNAc differs from other forms of protein glycosylation: (i) O-GlcNAc is not elongated or modified to form more complex glycan structures, (ii) O-GlcNAc is almost exclusively found on nuclear and cytoplasmic proteins rather than membrane proteins and secretory proteins, and (iii) O-GlcNAc is a highly dynamic modification that turns over more rapidly than the proteins which it modifies. O-GlcNAc is conserved across metazoans.

<span class="mw-page-title-main">High Affinity K+ transporter HAK5</span>

High Affinity K+ transporter HAK5 is a transport protein found on the cell surface membrane of plants under conditions of potassium deprivation. It is believed to act as a symporter for protons and the potassium ion, K+. Firstly discovered in barley, receiving the name of HvHAK1, it was soon after identified in the model plant Arabidopsis thaliana and named HAK5. These transporters belongs to the subgroup I of the KT-HAK-KUP family of plant proteins with obvious homology with both bacterial and fungal transport systems, which experienced a major diversification following land conquest. KT-HAK-KUP transporters are one of four different types of K+ transporter within the cell, but are unique as they do not have a putative pore forming domain like the other three; Shaker channels, KCO channels, HKT transporters. It is activated when the plant is situated in low soil with low potassium concentration, and has been shown to be located in higher concentration in the epidermis and vasculature of K+ deprived plants. By turning on, it increases the plants affinity (uptake) of potassium. Potassium plays a vital role in the plants growth, reproduction, immunity, ion homeostasis, and osmosis, which ensures the plants survival. It is the highest cationic molecule within the plant, accounting for 10% of the plants dry weight, which makes its uptake into the plant important. Each plant species has its own HAK5 transporter that is specific to that species and has different levels of affinity to K+. To operate and activate the HAK5 transporter, the external concentration of K+ must be lower than 10μM and up to 200μM. In Arabidopsis plants, when external potassium concentration is lower than 10μM, it is only HAK5 that is involved with the uptake of K+, then between 10 and 200μM both HAK5 and AKT1 are involved with the uptake of K+. HAK5 is coupled with CBL9/CIPK23 kinase's although the mechanism behind this has not yet been understood.

Seventeen elements or nutrients are essential for plant growth and reproduction. They are carbon (C), hydrogen (H), oxygen (O), nitrogen (N), phosphorus (P), potassium (K), sulfur (S), calcium (Ca), magnesium (Mg), iron (Fe), boron (B), manganese (Mn), copper (Cu), zinc (Zn), molybdenum (Mo), nickel (Ni) and chlorine (Cl). Nutrients required for plants to complete their life cycle are considered essential nutrients. Nutrients that enhance the growth of plants but are not necessary to complete the plant's life cycle are considered non-essential, although some of them, such as silicon (Si), have been shown to improve nutrent availability, hence the use of stinging nettle and horsetail macerations in Biodynamic agriculture. With the exception of carbon, hydrogen and oxygen, which are supplied by carbon dioxide and water, and nitrogen, provided through nitrogen fixation, the nutrients derive originally from the mineral component of the soil. The Law of the Minimum expresses that when the available form of a nutrient is not in enough proportion in the soil solution, then other nutrients cannot be taken up at an optimum rate by a plant. A particular nutrient ratio of the soil solution is thus mandatory for optimizing plant growth, a value which might differ from nutrient ratios calculated from plant composition.

References

  1. ↑ A. Nguyen, C.; Akiba, Y.; D. Kaunitz, J. (1 January 2012). "Recent Advances in Gut Nutrient Chemosensing". Current Medicinal Chemistry. 19 (1): 28–34. doi:10.2174/092986712803414033.
  2. ↑ Zagorski, Nick. "Nutrient Sensing, Signaling, & Regulation." Journal of Biological Chemistry. (2010): n. page. Web. 9 Apr. 2013. http://www.jbc.org/site/meeting2010/nutrient
  3. ↑ Molecular Cell, Volume 49, Issue 3, 379-387, 7 February 2013
  4. ↑ Yuan, Hai-Xin (2013). "Nutrient Sensing, Metabolism, and Cell Growth Control" (PDF). Molecular Cell. 49 (3): 379–387. doi:10.1016/j.molcel.2013.01.019. PMC   3587157 . PMID   23395268 . Retrieved 2 April 2013.
  5. ↑ Wang YP, Lei QY (2018). "Metabolic recoding of epigenetics in cancer". Cancer Commun (Lond). 38 (1): 1–8. doi: 10.1186/s40880-018-0302-3 . PMC   5993135 . PMID   29784032.
  6. ↑ Hietakangas, V; Cohen, SM (2009). "Regulation of tissue growth through nutrient sensing". Annu. Rev. Genet. 43: 389–410. doi:10.1146/annurev-genet-102108-134815. PMID   19694515.
  7. 1 2 Cui, Xiaofeng (2012). "Nutrient Sensing in Plants". Molecular Plant. 5 (6): 1167–1169. doi: 10.1093/mp/sss107 . PMID   23024206.
  8. ↑ Press, Cell. "Getting to the root of nutrient sensing". phys.org. Retrieved 30 December 2023.
  9. ↑ Amtmann, Anna; Hammond, John P.; Armengaud, Patrick; White, Philip J. (1 January 2005), "Nutrient Sensing and Signalling in Plants: Potassium and Phosphorus", Advances in Botanical Research, Incorporating Advances in Plant Pathology, Academic Press, vol. 43, pp. 209–257, retrieved 30 December 2023
  10. ↑ "What Nutrients do Plants need?". Agro Services International. 2002. Archived from the original on 27 April 2021.
  11. ↑ Higher Education Support | McGraw Hill Higher Education (PDF).
  12. ↑ Kruok, Gabriel; Benoît, Lacombe; Agnieszka, Bielach; Perrine-Walker, Francine; Malinska, Katerina; Mounier, Emmanuelle; Hoyerova, Klara; Tillard, Pascal; Leon, Sarah; Ljung, Karin; Zazimalova, Eva (15 June 2010). "Nitrate-Regulated Auxin Transport by NRT1.1 Defines a Mechanism for Nutrient Sensing in Plants". Developmental Cell. 18 (6): 927–937. doi: 10.1016/j.devcel.2010.05.008 . PMID   20627075.
  13. 1 2 3 4 Ho, Cheng-Hsun; Tsay, Yi-Fang (October 2010). "Nitrate, ammonium, and potassium sensing and signaling". Current Opinion in Plant Biology. 13 (5): 604–610. doi: 10.1016/j.pbi.2010.08.005 . PMID   20833581.
  14. 1 2 3 4 Coruzzi, Gloria M; Zhou, Li (1 June 2001). "Carbon and nitrogen sensing and signaling in plants: emerging 'matrix effects'". Current Opinion in Plant Biology. 4 (3): 247–253. doi:10.1016/s1369-5266(00)00168-0. PMID   11312136.
  15. ↑ Dove, Alan (9 April 2009). "Nutrient Sensing: How the Brain and Gut Regulate Food Intake" . Diabetes & Obesity Discussion Group. New York Academy of Sciences (NYAS).
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