A 78-kDa glucose-regulated protein is involved in the decrease of interleukin-6 secretion by lead treatment from...

Area of Science:

• Neuroscience
• Cell Biology
• Molecular Biology

Background:

• Interleukin-6 (IL-6) is a crucial cytokine in the central nervous system, primarily produced by microglia and astrocytes.
• Understanding the mechanisms of IL-6 secretion is vital for comprehending its diverse roles in neurological functions and diseases.

Purpose of the Study:

• To investigate the mechanism of IL-6 secretion from astrocytes.
• To explore the role of glucose-regulated protein 78 (GRP78) in IL-6 secretion.
• To examine the effect of lead (Pb) exposure on IL-6 secretion.

Main Methods:

• Constructed chimeric proteins: IL-6 fused with fluorescent proteins (EGFP, DsRed2) and GRP78 fused with EGFP.
• Utilized double-stranded RNA interference to deplete GRP78.
• Employed co-expression, co-localization, and co-immunoprecipitation assays.
• Assessed the impact of lead exposure using Pb-affinity chromatography.

Main Results:

• IL-6-EGFP and IL-6-DsRed2 chimeras demonstrated secretory properties from astrocytes.
• GRP78 depletion attenuated IL-6-EGFP secretion.
• Co-expression with a dysfunctional GRP78-EGFP chimera abolished IL-6-DsRed2 secretion, with both proteins co-localizing.
• IL-6 and GRP78 were found to be in the same protein complex.
• Lead (Pb) inhibited IL-6-EGFP secretion in a dose-dependent manner.
• Pb directly bound to GRP78, not IL-6.

Conclusions:

• IL-6-EGFP and IL-6-DsRed2 chimeras serve as effective imaging probes for studying IL-6 secretion in living cells.
• GRP78 plays a significant role in the secretion of IL-6 from astrocytes.
• Lead (Pb) inhibits astrocyte IL-6 secretion by targeting GRP78.