Fyn

Fyn is a Src family tyrosine kinase represented in brain by the neuronal isoform p59FynB, where Src and Fyn constitute the two main tyrosine kinases involved in neuronal growth and myelination^[1]. Mechanistically, Fyn participates in Src-family signaling modules that regulate inflammation, apoptosis, neuroinflammation, and epileptogenesis in experimental systems^[2][3]. In pulmonary endothelial inflammation models, fyn knockdown increased caspase-3 activity, reduced viable cell numbers, and intensified LPS-induced lung injury in fyn−/− mice, identifying Fyn as a negative regulator of inflammation-induced apoptosis^[2]. In temporal lobe epilepsy models, the Fyn-PKCδ pathway linked status epilepticus to neuroinflammation and epileptogenesis, while saracatinib reduced seizures, gliosis, neurodegeneration, phosphorylated Fyn/Src-419, PKCδ-tyr311, nitrooxidative stress, and proinflammatory cytokines^[3]. Compared with related isoforms, Fyn showed an opposite endothelial apoptosis phenotype to Yes, because yes knockdown lowered caspase-3 activity and increased viable cells under cytomix stimulation^[2]. For experimental applications, saracatinib functions as a Src/Fyn tyrosine kinase inhibitor for probing epileptogenesis-associated neuroinflammatory and nitrooxidative pathways^[3].