Croquemort elicits activation of the immune deficiency pathway in ticks.
Anya J O'NealNisha SinghAgustin RolandelliHanna J Laukaitis-YouseyXiaowei WangDana K ShawBrianna D YoungSukanya NarasimhanShraboni DuttaGreg A SnyderSourabh SamaddarLiron MarninL Rainer ButlerMaria Tays MendesFrancy E Cabrera PazLuisa M ValenciaEric John SundbergErol FikrigUtpal PalDavid J WeberJoao H F PedraPublished in: Proceedings of the National Academy of Sciences of the United States of America (2023)
The immune deficiency (IMD) pathway directs host defense in arthropods upon bacterial infection. In Pancrustacea, peptidoglycan recognition proteins sense microbial moieties and initiate nuclear factor-κB-driven immune responses. Proteins that elicit the IMD pathway in non-insect arthropods remain elusive. Here, we show that an Ixodes scapularis homolog of croquemort (Crq), a CD36-like protein, promotes activation of the tick IMD pathway. Crq exhibits plasma membrane localization and binds the lipid agonist 1-palmitoyl-2-oleoyl- sn -glycero-3-phosphoglycerol. Crq regulates the IMD and jun N-terminal kinase signaling cascades and limits the acquisition of the Lyme disease spirochete B. burgdorferi . Additionally, nymphs silenced for crq display impaired feeding and delayed molting to adulthood due to a deficiency in ecdysteroid synthesis. Collectively, we establish a distinct mechanism for arthropod immunity outside of insects and crustaceans.