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Formyl peptide receptor 2 (FPR2) has been shown to mediate the cytotoxic effects of the β amyloid peptide Aβ42 and serves as a receptor for humanin, a peptide that protects neuronal cells from damage by Aβ42, implying its involvement in the pathogenesis of Alzheimer's disease (AD). However, the interaction pattern between FPR2 and Aβ42 or humanin remains unknown. Here we report the structures of FPR2 bound to Gi and Aβ42 or N-formyl humanin (fHN). Combined with functional data, the structures reveal two critical regions that govern recognition and activity of Aβ42 and fHN, including a polar binding cavity within the receptor helical bundle and a hydrophobic binding groove in the extracellular region. In addition, the structures of FPR2 and FPR1 in complex with different formyl peptides were determined, providing insights into ligand recognition and selectivity of the FPR family. These findings uncover key factors that define the functionality of FPR2 in AD and other inflammatory diseases and would enable drug development. The formyl peptide receptor 2 (FPR2) is involved in the pathogenesis of Alzheimer's disease. Structures of FPR2 bound to Aβ42, humanin, or formyl peptides offer insight into Aβ42 neurotoxicity, humanin neuroprotection, and FPR ligand selectivity [ABSTRACT FROM AUTHOR]

Parental experiences can affect the phenotypic plasticity of offspring. In locusts, the population density that adults experience regulates the number and hatching synchrony of their eggs, contributing to locust outbreaks. However, the pathway of signal transmission from parents to offspring remains unclear. Here, we find that transcription factor Forkhead box protein N1 (FOXN1) responds to high population density and activates the polypyrimidine tract-binding protein 1 (Ptbp1) in locusts. FOXN1-PTBP1 serves as an upstream regulator of miR-276, a miRNA to control egg-hatching synchrony. PTBP1 boosts the nucleo-cytoplasmic transport of pre-miR-276 in a "CU motif"-dependent manner, by collaborating with the primary exportin protein exportin 5 (XPO5). Enhanced nuclear export of pre-miR-276 elevates miR-276 expression in terminal oocytes, where FOXN1 activates Ptbp1 and leads to egg-hatching synchrony in response to high population density. Additionally, PTBP1-prompted nuclear export of pre-miR-276 is conserved in insects, implying a ubiquitous mechanism to mediate transgenerational effects., (© 2024. The Author(s).)

Major groups of jawed vertebrates exhibit contrasting conditions of dermal plates and scales. But the transition between these conditions remains unclear due to rare information on taxa occupying key phylogenetic positions. The 425-million-year-old fish Entelognathus combines an unusual mosaic of characters typically associated with jawed stem gnathostomes or crown gnathostomes. However, only the anterior part of the exoskeleton was previously known for this very crownward member of the gnathostome stem. Here, we report a near-complete post-thoracic exoskeleton of Entelognathus. Strikingly, its scales are large and some are rhomboid, bearing distinctive peg-and-socket articulations; this combination was previously only known in osteichthyans and considered a synapomorphy of that group. The presence in Entelognathus of an anal fin spine, previously only found in some stem chondrichthyans, further illustrates that many characters previously thought to be restricted to specific lineages within the gnathostome crown likely arose before the common ancestor of living jawed vertebrates., (© 2023. The Author(s).)