UC San Diego

The innate immune response is an important component of wound healing, but must be negatively regulated to prevent continuous reaction to a one-time injury. Death Associated Protein Kinase (DAP Kinase) has been shown to negatively regulate this response in C. elegans by acting upstream of the TIR-1/p38 MAP Kinase cascade controlling the neuropeptidelike antimicrobial peptides. We show in our experiments that DAP Kinase acts upstream of the Protein Kinase C TPA-1, and downstream of the G[alpha] subunit GPA -12 to regulate not only this pathway but a second TGF- [Beta] pathway controlling the caenacin antimicrobial peptides as well. Our results also suggest that the worm can compensate for the loss of components in its innate immune response pathways, both with the activity of parallel pathways and with redundant components within a pathway. dapk-1(ju4) morphological defects were previously found to be suppressed by the sydn-1(ju541) mutation. We show that DAP Kinase and SYDN-1 interact autonomously in the epidermis, and that DAPK possibly regulates SYDN-1's role in mRNA 3' end processing. Finally, we mapped two novel suppressors of dapk-1(ju4) defects, ju697 and ju698, to chromosome I and chromosome X respectively. We predict that these mutations are most likely in the genes dhc-1, which encodes a dynein heavy chain homolog, and pqn-34, which encodes a microtubule minus-end binding protein, known to promote microtubule stability and anchoring in other species. Our results hint at previously unknown roles for DAP Kinase, including involvement in mRNA 3' end processing and microtubule dynamics in the worm