Neuronal Necroptosis Drives Neuroinflammation and Cognitive Decline Independent of Neuronal Cell Death

This study investigates transcriptomic changes in a novel neuron-specific Mlkl knockin (nMlkl-KI) mouse model following tamoxifen-induced MLKL expression in neurons. Mlkl-KI mice were generated on a C57BL/6J background using a transgene construct containing 3xFLAG-tagged Mlkl cDNA inserted into the Rosa26 locus with a loxP-flanked stop cassette. Hemizygous Mlkl-KI females were crossed with homozygous Slick-H-Cre (Thy1-CreERT2-EYFP) males to produce mice expressing MLKL selectively in neurons upon tamoxifen induction. At 45 days of age, mice were treated with tamoxifen (60 mg/kg, intraperitoneally) or corn oil for 5 consecutive days. Brain cortex tissue was collected and RNA was extracted for sequencing. At 12-months of age, nMlkl-KI mice exhibited significant cognitive impairment compared to control mice as measured by a continuous homecage discrimination learning with the Noldus PhenoTyper. Unbiased stereological analysis revealed no loss in neuronal number in the cortex and hippocampus, suggesting neuronal dysfunction rather than neuronal death was responsible for the reduced cognition observed in the nMlkl-KI mice. Transcriptomic analysis of the cortex revealed an upregulation of pathways associated with age-related neurodegenerative diseases as well as chemokine and TNF signaling in the nMlkl-KI mice.