BRAF-V600E utilizes post-transcriptional mechanisms to amplify LPS-induced TNF production in dendritic cells of Langerhans Cell Histiocytosis

Langerhans Cell Histiocytosis (LCH) is an inflammatory disease characterized by abnormal dendritic cells (DCs) with hyperactive ERK signaling, called “LCH cells”. Since DCs rely on ERK signaling to produce inflammatory signaling molecules in response to pathogenic cues, we hypothesized that hyperactive ERK will enhance DC inflammatory responses. We utilized the BRAF-V600E fl/+: CD11c-Cre mouse model of LCH which hyperactivates MAPK/ERK signaling in DCs. We cultured bone-marrow derived dendritic cells (BMDCs) from LCH and control mice (BRAF-V600E fl/+: Cre0) and stimulated them with LPS with or without a specific BRAF-V600E inhibitor. Polysome Profiling revealed a large and irreversible increase in levels of polysome bound RNA in the LCH-BMDCs compared to WT. We defined the LCH translatome by analyzing total and polysome-bound RNA from BMDCs using the Anota2seq program, which revealed a BRAF-V600E-mediated selective increase in LPS-induced inflammatory proteins. Overall design: Paired total and polysome-bound RNA from LPS-stimulated BMDCs (WT vs LCH; n=3 biological repeats) was used to define the LCH translatome via Anota2seq.