scholarly journals Physiological Role of Bile Acids Modified by the Gut Microbiome

2021 ◽  
Vol 10 (1) ◽  
pp. 68
Author(s):  
Yoshimitsu Kiriyama ◽  
Hiromi Nochi
Keyword(s):  
Cell Surface ◽  
Bile Acids ◽  
Terminal Ileum ◽  
Gut Microbiome ◽  
Physiological Role ◽  
Systemic Circulation ◽  
Nervous Systems ◽  
Physiological Regulation ◽  
Surface Receptors

Bile acids (BAs) are produced from cholesterol in the liver and are termed primary BAs. Primary BAs are conjugated with glycine and taurine in the liver and then released into the intestine via the gallbladder. After the deconjugation of glycine or taurine by the gut microbiome, primary BAs are converted into secondary BAs by the gut microbiome through modifications such as dehydroxylation, oxidation, and epimerization. Most BAs in the intestine are reabsorbed and transported to the liver, where both primary and secondary BAs are conjugated with glycine or taurine and rereleased into the intestine. Thus, unconjugated primary Bas, as well as conjugated and unconjugated secondary BAs, have been modified by the gut microbiome. Some of the BAs reabsorbed from the intestine spill into the systemic circulation, where they bind to a variety of nuclear and cell-surface receptors in tissues, whereas some of the BAs are not reabsorbed and bind to receptors in the terminal ileum. BAs play crucial roles in the physiological regulation of various tissues. Furthermore, various factors, such as diet, age, and antibiotics influence BA composition. Here, we review recent findings regarding the physiological roles of BAs modified by the gut microbiome in the metabolic, immune, and nervous systems.

Compartmentalization of protein traffic in insulin-sensitive cells

1996 ◽  
Vol 271 (1) ◽  
pp. E1-E14 ◽  
Author(s):  
K. V. Kandror ◽  
P. F. Pilch
Keyword(s):  
Cell Surface ◽  
Physiological Role ◽  
Fat Cells ◽  
Protein Traffic ◽  
Glut 1 ◽  
Glut 4 ◽  
Factor Ii ◽  
Nutritional Needs

Insulin-sensitive cells, adipocytes and myocytes, translocate a number of intracellular proteins to the cell surface in response to insulin. Among these proteins are glucose transporters 1 and 4 (GLUT-1 and GLUT-4, respectively), receptors for insulin-like growth factor II (IGF-II)/mannose 6-phosphate (Man-6-P) and transferrin, the aminopeptidase gp 160, caveolin, and a few others. In the case of insulin-activated glucose transport, this translocation has been proven to be the major, if not the only regulatory mechanism of this process. It seems likely that the cell surface recruitment of the IGF-II/Man-6-P and transferrin receptors also serves the nutritional needs of cells, whereas the physiological role of the aminopeptidase gp160 remains uncertain. Analysis of the compartmentalization and trafficking pathways of translocatable proteins in fat cells identified more than one population of recycling vesicles, although all have identical sedimentation coefficients and buoyant densities in vitro. GLUT-4-containing vesicles include essentially all the intracellular GLUT-4, gp160, and the acutely recycling populations of receptors for IGF-II/Man-6-P and transferrin. Besides these proteins, which can be considered as vesicle “cargo”, GLUT-4-containing vesicles have other components, like secretory carrier-associated membrane proteins (SCAMP), Rab(s), and vesicle-associated membrane protein (VAMP)/cellubrevin, which are ubiquitous to secretory vesicles and granules from different tissues. GLUT-1 and caveolin are excluded from GLUT-4-containing vesicles and form different vesicular populations of unknown polypeptide composition. In skeletal muscle, two independent populations of GLUT-4-containing vesicles are found, insulin sensitive and exercise sensitive, which explains the additive effect of insulin and exercise on glucose uptake. Both vesicular populations are similar to each other and to analogous vesicles in fat cells.

scholarly journals Integrins as architects of cell behavior

2016 ◽  
Vol 27 (19) ◽  
pp. 2885-2888 ◽  
Author(s):  
Charles H. Streuli
Keyword(s):  
Extracellular Matrix ◽  
Mammary Gland ◽  
Cell Surface ◽  
Cell Function ◽  
External Environment ◽  
Cell Behavior ◽  
Cell Surface Receptors ◽  
Surface Receptors ◽  
Mammary Gland Differentiation

Integrins are cell surface receptors that bind cells to their physical external environment, linking the extracellular matrix to cell function. They are essential in the biology of all animals. In the late 1980s, we discovered that integrins are required for the ability of breast epithelia to do what they are programmed to do, which is to differentiate and make milk. Since then, integrins have been shown to control most other aspects of phenotype: to stay alive, to divide, and to move about. Integrins also provide part of the mechanism that allows cells to form tissues. Here I discuss how we discovered that integrins control mammary gland differentiation and explore the role of integrins as central architects of other aspects of cell behavior.

scholarly journals Differential Regulation of the Uridine Nucleotide-activated P2Y4 and P2Y6 Receptors

2000 ◽  
Vol 276 (15) ◽  
pp. 11939-11948 ◽  
Author(s):  
Amy E. Brinson ◽  
T. Kendall Harden
Keyword(s):  
Cell Surface ◽  
Inositol Phosphate ◽  
Complete Recovery ◽  
Differential Regulation ◽  
Cell Surface Receptors ◽  
Surface Receptors ◽  
Astrocytoma Cells ◽  
Truncation Mutant ◽  
Uridine Nucleotide

Agonist-promoted regulation of the uridine nucleotide-activated human P2Y4 receptor (P2Y4-R) and P2Y6 receptor (P2Y6-R) was studied. Incubation of P2Y4-R-expressing 1321N1 human astrocytoma cells with the cognate agonist UTP resulted in rapid desensitization of the inositol phosphate response and a 50% loss of cell surface receptors. In contrast, incubation of P2Y6-R-expressing cells with the cognate agonist UDP caused neither rapid desensitization nor rapid loss of cell surface receptors. Removal of UTP from the medium of UTP-pretreated cells resulted in rapid and complete recovery of surface P2Y4-R even after 12 h of agonist treatment. Although extended incubation with UDP also caused a loss of surface P2Y6-R, rapid recovery of surface P2Y6-R did not occur following removal of agonist. Pharmacological studies indicated that neither protein kinase C nor other Ca2+-activated kinases were involved in agonist-promoted desensitization or loss of surface P2Y4-R or P2Y6-R. Mutational analyses were carried out to identify domains involved in agonist-dependent regulation of P2Y4-R. Sequential truncation of the carboxyl-terminal domain revealed that sequence between amino acids 332 and 343 was necessary for UTP-promoted desensitization and internalization. Further mutational analyses of the three serines in this domain confirmed that Ser-333 and Ser-334 play a major role in these agonist-promoted changes in P2Y4-R. Experiments were carried out with [32P]Pi-labeled cells to ascertain the role of phosphorylation in regulation of P2Y4-R. Incubation with UTP for 2 min caused a marked increase in phosphorylation of both the wild-type P2Y4-R and the P2Y4–343 truncation mutant. In contrast, no UTP-promoted phosphorylation of the P2Y4–332 truncation mutant was observed. Taken together, these results demonstrate differential regulation of uridine nucleotide-activated P2Y4-R and P2Y6-R and indicate that Ser-333 and Ser-334 in the carboxyl terminus of P2Y4-R are important for UTP-dependent phosphorylation, desensitization, and loss of surface receptors.

scholarly journals The Role of Cell Surface Receptors in the Activation of Human B Cells by Phosphorothioate Oligonucleotides

2000 ◽  
Vol 165 (3) ◽  
pp. 1438-1445 ◽  
Author(s):  
Hua Liang ◽  
Charles F. Reich ◽  
David S. Pisetsky ◽  
Peter E. Lipsky
Keyword(s):  
B Cells ◽  
Cell Surface ◽  
Cell Surface Receptors ◽  
Surface Receptors ◽  
Human B Cells

scholarly journals FAK and PYK2 are specifically associated with the activated phagocytic receptor complexes from human U937 cells.

2021 ◽  
Author(s):  
Marwan G. AbidAlthagafi
Keyword(s):  
Cell Surface ◽  
Tyrosine Kinases ◽  
Laser Scanning ◽  
Surface Proteins ◽  
Protein Tyrosine Kinases ◽  
Macrophage Cell ◽  
Protein Tyrosine ◽  
Surface Receptors ◽  
Receptor Complexes

The innate immune system is the first shield against foreign attack inside the human body, and it is usually carried out with phagocytosis. An essential macrophage cell surface protein is the Fc receptor which contributes to the engulfment of unknown antigens. One of the important members of Fc receptors is the gamma receptor that binds to the immunoglobulin G (IgG) ligand. Another key receptor in this study is the CD36 receptor, which plays a crucial role in the progression of atherosclerosis, the hardening of arteries, with its ligand oxidized low-density lipoprotein (OxLDL). In this report, protein tyrosine kinase enzymes have been detected in the involvement of receptor complexes with human U937 macrophages, specifically PTK2 and PTK2b genes. Protein tyrosine kinases were known to promote cell migration as a main player in intracellular signal transduction cascades in relation to extracellular stimuli. Cell surface proteins are essential for the immunization of various diseases; yet, the molecular machinery of surface receptors remains unclear. This research primarily examined the dynamic nature of protein tyrosine kinases in an ongoing investigation of macrophage cell surface receptors, particularly the role of Fc γ and CD36 receptors with their ligands IgG and oxLDL coated beads in phagocytosis. Our report demonstrates a novel role of PTK2 and PTK2b functions in relation to U937 CD36-mediated phagocytosis. The Phagocytic efficiency of U937 macrophages was analyzed using laser scanning confocal microscope after silencing the cells with siRNA followed by quantitative counting of phagocytosis. The PF drug FAK inhibitor was also introduced to compare the phagocytic efficiency of siRNA cells.

scholarly journals Studies on the role of specific cell surface receptors in the removal of lipoprotein (a) in man.

1983 ◽  
Vol 71 (5) ◽  
pp. 1431-1441 ◽  
Author(s):  
F Krempler ◽  
G M Kostner ◽  
A Roscher ◽  
F Haslauer ◽  
K Bolzano ◽  
...  
Keyword(s):  
Cell Surface ◽  
Cell Surface Receptors ◽  
Specific Cell ◽  
Lipoprotein A ◽  
Surface Receptors ◽  
Specific Cell Surface

scholarly journals Endothelial Cell Inflammation and Barriers Are Regulated by the Rab26-Mediated Balance between β2-AR and TLR4 in Pulmonary Microvessel Endothelial Cells

2019 ◽  
Vol 2019 ◽  
pp. 1-10 ◽  
Author(s):  
Huaping Chen ◽  
Ming Yuan ◽  
Chunji Huang ◽  
Zhi Xu ◽  
Mingchun Li ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Endothelial Cell ◽  
Cell Membrane ◽  
Cell Surface ◽  
Cell Types ◽  
Tlr4 Expression ◽  
Barrier Dysfunction ◽  
Surface Receptors ◽  
G Protein Coupled

Rab26 GTPase modulates the trafficking of cell surface receptors, such as G protein-coupled receptors including α2-adrenergic receptors in some cell types. However, the effect of Rab26 on β2-adrenergic receptor (β2-AR) trafficking or/and Toll-like receptor 4 (TLR4) expression in human pulmonary microvascular endothelial cells (HPMECs) is still unclear. Here, we investigated the role of Rab26 in regulating the expression of β2-ARs and TLR4 in HPMECs and the effect of these receptors’ imbalance on endothelial cell barrier function. The results showed that there was unbalance expression in these receptors, where β2-AR expression was remarkably reduced, and TLR4 was increased on the cell membrane after lipopolysaccharide (LPS) treatment. Furthermore, we found that Rab26 overexpression not only upregulated β2-ARs but also downregulated TLR4 expression on the cell membrane. Subsequently, the TLR4-related inflammatory response was greatly attenuated, and the hyperpermeability of HPMECs also was partially relived. Taken together, these data suggest that basal Rab26 maintains the balance between β2-ARs and TLR4 on the cell surface, and it might be a potential therapeutic target for diseases involving endothelial barrier dysfunction.

scholarly journals Cell Responses to Extracellular α-Synuclein

Molecules ◽  
2019 ◽  
Vol 24 (2) ◽  
pp. 305 ◽  
Author(s):  
Alexei A. Surguchev ◽  
Fatemeh Nouri Emamzadeh ◽  
Andrei Surguchov
Keyword(s):  
Cell Surface ◽  
Close Association ◽  
Lewy Bodies ◽  
Cell Surface Receptors ◽  
Unfolded Proteins ◽  
Surface Receptors ◽  
Cell Responses ◽  
Biochemical Pathways ◽  
The Family

Synucleins are small naturally unfolded proteins involved in neurodegenerative diseases and cancer. The family contains three members: α-, β-, and -synuclein. α-Synuclein is the most thoroughly investigated because of its close association with Parkinson's disease (PD), dementia with Lewy bodies and multiple system atrophy. Until recently, the synuclein's research was mainly focused on their intracellular forms. However, new studies highlighted the important role of extracellular synucleins. Extracellular forms of synucleins propagate between various types of cells, bind to cell surface receptors and transmit signals, regulating numerous intracellular processes. Here we give an update of the latest results about the mechanisms of action of extracellular synucleins, their binding to cell surface receptors, effect on biochemical pathways and the role in neurodegeneration and neuroinflammation.

scholarly journals Genetic Characterization of a Cell Envelope-Associated Proteinase from Lactobacillus helveticus CNRZ32

1999 ◽  
Vol 181 (15) ◽  
pp. 4592-4597 ◽  
Author(s):  
Jeffrey A. Pederson ◽  
Gerald J. Mileski ◽  
Bart C. Weimer ◽  
James L. Steele
Keyword(s):  
Cell Surface ◽  
Deletion Mutant ◽  
Cell Envelope ◽  
Physiological Role ◽  
Lactobacillus Helveticus ◽  
Whole Cells ◽  
A Cell ◽  
Hydrolysis Of

ABSTRACT A cell envelope-associated proteinase gene (prtH) was identified in Lactobacillus helveticus CNRZ32. TheprtH gene encodes a protein of 1,849 amino acids and with a predicted molecular mass of 204 kDa. The deduced amino acid sequence of the prtH product has significant identity (45%) to that of the lactococcal PrtP proteinases. Southern blot analysis indicates thatprtH is not broadly distributed within L. helveticus. A prtH deletion mutant of CNRZ32 was constructed to evaluate the physiological role of PrtH. PrtH is not required for rapid growth or fast acid production in milk by CNRZ32. Cell surface proteinase activity and specificity were determined by hydrolysis of αs1-casein fragment 1-23 by whole cells. A comparison of CNRZ32 and its prtH deletion mutant indicates that CNRZ32 has at least two cell surface proteinases that differ in substrate specificity.

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