Evolutionary Conservation and Immunoregulatory Function of LOXL3 Gene in Lamprey.

Lysyl oxidase (LOX) family enzymes play a pivotal role in extracellular matrix (ECM) remodeling and tissue homeostasis, and have evolved diverse functions in vertebrate immunity and metabolism. However, the evolutionary trajectory of these multifunctional roles-particularly in jawless vertebrates-remains obscure. Here, we investigate LOXL3 in the lamprey (Lethenteron reissneri), a jawless vertebrate that retains ancestral features of early vertebrate evolution. Through comparative genomics and phylogenetic reconstruction, we identify Lr.LOXL3 as an orthologue within the vertebrate LOXL3 clade, preserving the conserved catalytic motifs shared across the LOX/LOXL1-4 family. Spatial expression profiling reveals predominant localization of Lr.LOXL3 in the endostyle and liver, with dynamic regulation upon immune challenge (PHA/LPS). Functional interrogation via siRNA knockdown and transcriptomic analysis uncovers a dual role for Lr.LOXL3 in coordinating both innate and adaptive immune responses, alongside reprogramming glycolipid metabolism to maintain immune-metabolic homeostasis. Notably, Lr.LOXL3 exhibits a transitional evolutionary state-retaining ancestral ECM-remodeling capacity while acquiring regulatory features absent in other agnathans but diversified among higher vertebrate paralogues. This intermediate architecture underscores the value of the lamprey as a model for investigating the origins of LOX gene diversification and the emergence of immune-metabolic integration across vertebrate evolution.