Intracellular signalling molecules

The antiinflammatory effects of statins likely result from their ability to inhibit the formation of mevalonic acid. Downstream products of this molecule include not only the end product, cholesterol, but also several isoprenoid intermediates that covalently modify ( pre-nylate ) certain key intracellular signaling molecules. Statin treatment reduces leukocyte adhesion, accumulation of macrophages, MMPs, tissue factor, and other proinflammatory mediators. By acting on the MHC class II transactivator (CIITA), statins also interfere with antigen presentation and subsequent T-cell activation. Statin treatment can also limit platelet activation in some assays as well. All these results support the concept that in addition to their favorable effect on the lipid profile, statins can also exert an array of antiinflammatory and immunomodulatory actions. 

The diversity of these subcellular actin structures is remarkable and appears to be determined by the interactions of many actin-binding proteins (ABPs) as well as by changes in the concentrations of intracellular signaling molecules such as Ca and cAMP, by small GTP-binding proteins, and by signals arising from mechanical stress. Approximately 50% of the actin molecules in most animal cells are unpolymerized subunits in the cytosolic pool and exist in a state of dynamic equilibrium with labile F-actin filamentous structures (i.e., new structures are formed while existing structures are renewed) (Hall, 1994). 

Inhibition of neurite growth is mediated through surface receptors and intracellular signaling molecules. 

Ca2+ is the main intracellular signalling molecule in smooth muscle. Fluctuation in local cytoplasmic [Ca2+] near Ca2+-sensitive effector molecules allows for specific regulation of multiple functions. These temporal fluctuations and spatial variations of cytoplasmic [Ca2+] are dependent on the interactions of ion transport proteins located in the plasma membrane (PM) and membranes of the sacoplasmic reticulum (SR), nuclear envelope and mitochondria. These... 

The formylated peptide fMet-Leu-Phe is probably the most commonly-used activator of neutrophils in vitro. It is used as a model agonist to study receptor-mediated processes, generating intracellular signalling molecules that then activate cell functions. This compound can, depending upon the concentration used, activate many varied functions, such as chemotaxis, aggregation, reactive oxidant production, cytoskeletal changes and (particularly in combination with cytochalasin B) degranulation. 

Neutrophil activation The production of intracellular signalling molecules... 

The activity of PLD on phosphatidylcholine generates phosphatidic acid, and this may be further metabolised by the enzyme phosphatidate phospho-hydrolase to form DAG (Fig. 6.19). Furthermore, the activity of DAG kinase can convert the DAG (generated either from phosphatidic acid or from the activity of PLC) back into phosphatidic acid. Both phosphatidic acid and DAG have functions as second messengers thus the activities of PLD, phosphatidate phosphohydrolase and DAG kinase all play important roles in the generation of these intracellular signalling molecules. 

The LF is the most disruptive to cellular functions and disables intracellular signaling molecules. It prevents macrophages from releasing tumor necrosis factor (TNF) and interleukin cytokines, although the production of TNF and cytokines in the macrophages is not impeded. The host s immune system is compromised and is unable to eliminate the anthrax bacillus. 

The cellular consequences of neurotransmission can be both short term (acute) and long term (chronic). Acutely, stimulation of neurotransmitter receptors alters levels of intracellular signaling molecules, which may induce the neuron to fire or alter the responsiveness of the neuron to further stimulation. Over time, the persistent activation of receptors that occurs with... 

The intracellular activation of enzymes in a signaling chain can lead to the formation of diffusible chemical signaling molecules in the cell. These intracellular signaling molecules are also termed second messengers. The second messenger molecules activate and recruit cognate enzymes for the further signal transduction. 

Intracellular Signal Molecules of the T and B Cell Antigen Receptors... 

Hydrolysis of cAMP cAMP is rapidly hydrolyzed to 5-AMP by cAMP phosphodiesterase, one of a family of enzymes that cleave the cyclic 3 5 -phosphodiester bond. 5-AMP is not an intracellular signalling molecule. Thus, the effects of neurotransmitter- or hormone-mediated increases of cAMP are rapidly terminated if the extracellular signal is removed. [Note Phosphodiesterase is inhibited by methylxanthine derivatives, such as theophylline and caffeine.3]... 

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