Inducer of gene expression

Another type of NR crosstalk, which has only recently been recognized, is the so-called nongenomic actions of several receptors that induce very rapid cellular effects. Effectively, evidence has accumulated over several decades that steroid receptors may have a role that does not require their transcriptional activation, such as modifying the activity of enzymes and ion channels. While the effects of steroids that are mediated by the modulation of gene expression do occur with a time lag of hours, steroids can induce an increase in several second messengers such as inositol triphosphate, cAMP, Ca2+, and the activation of MARK and PI3 kinase within seconds or minutes. Many mechanistic details of these nongenomic phenomena remain poorly understood. Notably, controversy still exists as to the identity of the receptors that initiate the non-genomic steroid actions. However, it now appears that at least some of the reported effects can be attributed to the same steroid receptors that are known as NRs. 

One of the questions confronting investigators in the HS field is whether fever or other acute phase reactants can induce HS gene expression. In vitro studies utilize extraordinary temperatures of 42 °C and higher. Core body temperatures may approach 40 °C as a result of fever. In most in vitro systems, this temperature does not lead to the HS response. However, there are reports that fever induces the increased synthesis of hsps in peripheral blood lymphocytes (Ciavarra, 1990). This response was observed in mononuclear cells exposed to febrile temperatures and in cells isolated from a medical intern who developed fever. 

Synthesis of New Methyl Esters of 3-Deoxy-D- ry /rro-2-hexulosonic acid (KDG) analogs, inducers of the Expression of Pectinase Genes in Bacteria Erwinia chrysanthemi... 

Figure 2 Structures of flavonoids present in root exudates of host plants and inducing nod gene expression in rhizobia (1) as 3,5,7,3 -tetrahydroxy-4 -methoxyflavanone, inducer in Rhizohium legiiminosarum bv. viciae (2) as 3, 4, 5, 7-tetrahydroxy-flavone, inducer in Rhizohium melilotr, (3) as 4, 7-dihydroxyisoflavone, inducer in Bradyrhizohium japonicum (4) as couinestrol, intermediate in phenylpropane metabolism, weak inducer. (From Ref. 64.)...

MUELLER-URI, F., PARTHIER, B., NOVER, L., Jasmonate-induced alteration of gene expression in barley leaf segments analyzed by in vivo and in vitro protein synthesis, Planta, 1988,176,241-247. 

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