Cellular compartment

About: Cellular compartment is a research topic. Over the lifetime, 1082 publications have been published within this topic receiving 53794 citations. The topic is also known as: cell compartmentation.

The Dynamic Parameter

Abstract: The viability of organisms is dependent on the controlled flow of information and metabolic/synthetic precursors between cellular compartments. Such processes are elaborated upon as a hierarchy of interdependence established between cells and tissues. Through the ebb and flow of signaling and metabolic molecules, dynamic linkages may be maintained between cells for the coordination, synchronization, and initiation of cellular cycles (Fig. 1). In this manner, organismal response to the environment may be viewed as the result of a linked web of dissipative molecular gradients across biological membranes that initiate and transmit environmental information and cellular status. Integration of these gradients over large numbers of cells and tissues collectively leads to spatial and/or temporal responses. The biological structures that serve as controllable elements for transmembrane molecular flow are generally classified as channels or pores that serve either as passive transport routes for low-molecular-weight molecules (Loewenstein, 1979; Nikaido and Nakae, 1979; Gunning and Overall, 1983) or as ion pumps or transporters requiring some type of coupled gradient dissipation or energy Open image in new window Figure 1 Dynamic linkages between organelles and cells. Chemical gradients are utilized to transmit information between the cell and the environment. The pathways involved in this transmission system are: lateral mobility of membrane receptors (1); transplasma membrane transport through channels, pores, and transporters (2); homotypic intercellular communication through gap junctions or plasmodesmata (3); nucleocytoplasmic transport (4); translysosomal or vacuolar membrane transport of H+ and ions (5); Golgi-mediated processing, secretion, and recycling (6); Golgi transport of newly synthesized proteins (cis-medial-trans) (7); heterotypic intercellular communication (8). R, N, and G represent membrane receptors, the nucleus, and Golgi, respectively. source for molecular transposition (Mitchell, 1979; Noma, 1983; Reuter et al., 1983). In most instances, the control of these channels is mediated by ligand-specific receptors that couple to the channels under activating conditions, initiating a cascade of enzymatic changes resulting in a modification of channel transport properties (Koshland, 1981; Bean et al., 1983; Hondeghem and Katzung, 1984). In other cases, transport channels and receptors are intimately linked, forming a common structure, as in the case of the nicotinic acid receptor/channel (Conti-Tronconi and Raftery, 1982).

Intracellular distribution of glutathionylated proteins in cultured dermal fibroblasts by immunofluorescence.

Abstract: S-glutathionylation is a mechanism of signal transduction by which cells respond effectively and reversibly to redox inputs. The glutathionylation regulates most cellular pathways. It is involved in oxidative cellular response to insult by modulating the transcription factor Nrf2 and inducing the expression of antioxidant genes (ARE); it contributes to cell survival through nuclear translocation of NFkB and activation of survival genes, and to cell death by modulating the activity of caspase 3. It is involved in mitotic spindle formation during cell division by binding cytoskeletal proteins thus contributing to cell proliferation and differentiation. Glutathionylation also interfaces with the mechanism of phosphorylation by modulating several kinases (PKA, CK) and phosphatases (PP2A, PTEN), thus allowing a cross talk between the two processes of signal transduction. Glutathionylation of proteins may also act on cell metabolism by modulating enzymes involved in glycosylation, in the Krebs cycle and in mitochondrial oxidative phosphorylation. Perturbations in protein glutathionylation status may contribute to the etiology of many diseases, thus it is clear the importance to visualize the distribution of glutathionylated proteins in subcellular compartments. This chapter describes the immunofluorescence technique that permits simultaneous detection of glutathionylated proteins and their localization in cellular compartments, using multiple stained cell samples. By confocal laser microscopy analysis of the immunofluorescent cells it is possible to obtain detailed information of submicroscopic structures inside cells and tissues, and to perform correct co-localization analysis between two proteins. The association between glutathione, nuclear lamina, and cytoskeleton has been investigated by employing a helpful assay consisting on the in situ extraction of the cellular matrix from cultured dermal fibroblasts followed by multiple stainings with several primary antibodies. This protocol can be used for the detection of the intracellular distribution and expression of interest proteins and can be customized for a large variety of cells and tissues.

Deoxyribonucleic Acid Synthesis in Isolated Chloroplasts and Chloroplast Extracts of Maize

Abstract: Isolated chloroplasts are capable of synthesizing chloroplast DNA in the presence of Mg2+ and deoxynucleoside triphosphates. The in vitro reaction proceeds for at least 60 min and is inhibited by KCl and N-ethylmaleimide. Stretches of several hundred nucleotides in length are synthesized within an hour. Little or no inhibition is shown by aphidicolin (an inhibitor of eukaryotic DNA polymerase a), dideoxythymidine triphosphate (an inhibitor of eukaryotic DNA polymerases P and y), nalidixic acid, or rifampicin. Ethidium bromide is a moderate inhibitor of DNA synthesis in the isolated chloro- Eukaryotic cells are characterized by compartmentalization of those cellular components which contain their own genetic apparatus. In animal cells, the nuclear compartment has a genomic organization and DNA replication machinery which is apparently quite different from that in the other cellular compartment, the mitochondria (Kasamatsu et al., 1974). Higher plant cells contain three, rather than two, cellular compartments (Olson, 198 1) since they contain another au-

Intracellular Citrate/acetyl-CoA flux and endoplasmic reticulum acetylation: Connectivity is the answer

Abstract: Key cellular metabolites reflecting the immediate activity of metabolic enzymes as well as the functional metabolic state of intracellular organelles can act as powerful signal regulators to ensure the activation of homeostatic responses. The citrate/acetyl-CoA pathway, initially recognized for its role in intermediate metabolism, has emerged as a fundamental branch of this nutrient-sensing homeostatic response. Emerging studies indicate that fluctuations in acetyl-CoA availability within different cellular organelles and compartments provides substrate-level regulation of many biological functions. A fundamental aspect of these regulatory functions involves Nε-lysine acetylation.Here, we will examine the emerging regulatory functions of the citrate/acetyl-CoA pathway and the specific role of the endoplasmic reticulum (ER) acetylation machinery in the maintenance of intracellular crosstalk and homeostasis. These functions will be analyzed in the context of associated human diseases and specific mouse models of dysfunctional ER acetylation and citrate/acetyl-CoA flux. A primary objective of this review is to highlight the complex yet integrated response of compartment- and organelle-specific Nε-lysine acetylation to the intracellular availability and flux of acetyl-CoA, linking this important post-translational modification to cellular metabolism.The ER acetylation machinery regulates the proteostatic functions of the organelle as well as the metabolic crosstalk between different intracellular organelles and compartments. This crosstalk enables the cell to impart adaptive responses within the ER and the secretory pathway. However, it also enables the ER to impart adaptive responses within different cellular organelles and compartments. Defects in the homeostatic balance of acetyl-CoA flux and ER acetylation reflect different but converging disease states in humans as well as converging phenotypes in relevant mouse models. In conclusion, citrate and acetyl-CoA should not only be seen as metabolic substrates of intermediate metabolism but also as signaling molecules that direct functional adaptation of the cell to both intracellular and extracellular messages. Future discoveries in CoA biology and acetylation are likely to yield novel therapeutic approaches.