Signal transduction in cells following binding of chemoattractants to membrane receptors

1988 ◽  
Vol 55 (1) ◽  
pp. 65-80
Author(s):  
Susan B. Dillon ◽  
Margrith W. Verghese ◽  
Ralph Snyderman
Author(s):  
Stephen R. Hammes ◽  
Carole R. Mendelson

The capacity of a cell to respond to a particular hormone depends on the presence of cellular receptors specific for that hormone. After binding hormone, the receptor is biochemically and structurally altered, resulting in its activation; the activated receptor then mediates all of the actions of the hormone on the cell. The steroid and thyroid hormones as well as retinoids and 1,25-dihydroxyvitamin D3 diffuse freely through the lipophilic plasma membrane of the cell and interact with receptors that are primarily within the nucleus. On activation, the receptors alter the transcription of specific genes, resulting in changes in the levels of specific messenger RNAs (mRNAs), which are in turn translated into proteins. Hormones that are water soluble, such as the peptide and polypeptide hormones, catecholamines, and other neurotransmitters, as well as the relatively hydrophobic prostaglandins, interact with receptors in the plasma membrane. After hormone binding, the activated membrane receptors initiate signal transduction cascades that result in changes in enzyme activities and alterations in gene expression. In this chapter, the properties of various classes of receptors that are localized within the plasma membranes of target cells and the signal transduction mechanisms that mediate interactions with their ligands will first be addressed. This will be followed by consideration of the structural properties of the nuclear hormone receptors, the events that result in their activation, and the mechanisms whereby the activated nuclear receptors alter the expression of specific genes. Finally, a number of endocrine disorders that are caused by alterations in the number and/or function of plasma membranes and nuclear receptors will be reviewed. The function of a receptor is to recognize a particular hormone among all the molecules in the environment of the cell at a given time and, after binding the hormone, to transmit a signal that ultimately results in a biological response. Hormones are normally present in the circulation in extremely low concentrations, ranging from 10 –9 to 10 –11 M.


1997 ◽  
Vol 324 (2) ◽  
pp. 653-658 ◽  
Author(s):  
Laura LUO ◽  
Tony CRUZ ◽  
Christopher McCULLOCH

The cytokine interleukin 1 (IL-1) is an important mediator of connective-tissue destruction in arthritic joints but the mechanisms by which IL-1 mediates signal transduction in chondrocytes is poorly understood. Previous results have indicated that IL-1 receptors co-localize with focal adhesions [Qwarnstrom, Page, Gillis and Dower (1988) J. Biol. Chem. 263, 8261–8269], discrete adhesive domains of cells that function in cell attachment and possibly in signal transduction. We have determined whether focal adhesions restrict IL-1-induced Ca2+ signalling in primary cultures of bovine chondrocytes. In cells grown for 24 h on fibronectin, the basal intracellular Ca2+ ion concentration ([Ca2+]i) was 100±3 nM. Optimal increases of [Ca2+]i above baseline were induced by 10 nM IL-1 (183±30 nM above baseline). There was no significant difference between cells plated on fibronectin or type II collagen (P > 0.2; 233±90 nM above baseline). Ca2+ transients were significantly decreased by the inclusion of 0.5 mM EGTA in the bathing buffer (74±11 nM above baseline), and 1 μM thapsigargin completely blocked Ca2+ transients. Cells plated on poly-(l-lysine) or suspended cells showed no Ca2+ increases, whereas cells grown on fibronectin exhibited IL-1-induced Ca2+ responses that corresponded temporally to the time-dependent cell spreading after plating on fibronectin. Cells plated on poly-(l-lysine) and incubated with fibronectin-coated beads exhibited vinculin staining in association with the beads. In identical cell preparations, IL-1 induced a 136±39 nM increase of [Ca2+]i above baseline in response to 10 nM IL-1β. There were no IL-1-induced Ca2+ increases when cells on poly-(l-lysine) were incubated with fibronectin-coated beads for only 15 min at 37 °C, in cells maintained for 3 h at 4 °C, in cells incubated with BSA beads for 3 h at 37 °C, or in cells pretreated with cytochalasin D. Labelling of IL-1 receptors with 125I-IL-1β showed 3-fold more specific labelling of focal adhesion complexes in cells incubated with fibronectin-coated beads compared with cells incubated with BSA-coated beads, indicating that IL-1 receptor binding or the number of IL-1 receptors was increased in focal adhesions. These results indicate that, in chondrocytes, IL-1-induced Ca2+ signalling is dependent on focal adhesion formation and that focal adhesions recruit IL-1 receptors by redistribution in the cell membrane.


2006 ◽  
Vol 51 (11) ◽  
pp. 2102-2112 ◽  
Author(s):  
Kohjiroh Ishihara ◽  
Yasuo Yamaguchi ◽  
Shinichiro Uchino ◽  
Takashi Furuhashi ◽  
Shinwa Yamada ◽  
...  

1999 ◽  
Vol 36 (Suppl. 1) ◽  
pp. 42-47 ◽  
Author(s):  
I. Marshall ◽  
Richard P. Burt ◽  
Christopher R. Chapple

1997 ◽  
Vol 323 (1) ◽  
pp. 239-244 ◽  
Author(s):  
Liliana BUSCONI ◽  
Paula M. BOUTIN ◽  
Bradley M. DENKER

Heterotrimeric guanine nucleotide binding proteins (G-proteins) transmit signals from membrane receptors to a variety of intracellular effectors. G-proteins reversibly associate with components of the signal transduction system, yet remain membrane attached throughout the cycle of activation. The Gα subunits remain attached to the plasma membrane through a combination of factors that are only partially defined. We now demonstrate that amino acids within the N-terminal domain of Gα subunits are involved in membrane binding. We used in vitro translation, a technique widely utilized to characterize functional aspects of G-proteins, and interactions with donor-acceptor membranes to demonstrate that amino acids 11-14 of Gαo contribute to membrane binding. The membrane binding of Gαo lacking amino acids 11-14 (D[11-14]) was significantly reduced at all membrane concentrations in comparison with wild-type Gαo. Several other N-terminal mutants of Gαo were characterized as controls, and these results indicate that differences in myristoylation, palmitoylation and βγ interactions do not account for the reduced membrane binding of D[11-14]. Furthermore, when membrane attachment of Gαo and mutants was characterized in transiently transfected 35S-labelled and [3H]myristate-labelled COS cells, amino acids 11-14 contributed to membrane binding. These studies reveal that membrane binding of Gα subunits occurs by a combination of factors that include lipids and amino acid sequences. These regions may provide novel sites for interaction with membrane components and allow additional modulation of signal transduction.


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