Second messenger Ap<sub>4</sub>A polymerizes target protein HINT1 to transduce signals in FcεRI-activated mast cells.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 31604935.
- Also identified by DOI 10.1038/s41467-019-12710-8 and PMC identifier 6789022.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Signal transduction systems enable organisms to monitor their external environments and accordingly adjust the cellular processes. In mast cells, the second messenger Ap<sub>4</sub>A binds to the histidine triad nucleotide-binding protein 1 (HINT1), disrupts its interaction with the microphthalmia-associated transcription factor (MITF), and eventually activates the transcription of genes downstream of MITF in response to immunostimulation. How the HINT1 protein recognizes and is regulated by Ap<sub>4</sub>A remain unclear. Here, using eight crystal structures, biochemical experiments, negative stain electron microscopy, and cellular experiments, we report that Ap<sub>4</sub>A specifically polymerizes HINT1 in solution and in activated rat basophilic leukemia cells. The polymerization interface overlaps with the area on HINT1 for MITF interaction, suggesting a possible competitive mechanism to release MITF for transcriptional activation. The mechanism depends precisely on the length of the phosphodiester linkage of Ap<sub>4</sub>A. These results highlight a direct polymerization signaling mechanism by the second messenger.
Medical subject headings
- Dinucleoside Phosphates
- Mast Cells
- Nerve Tissue Proteins