TREM2 and neurodegenerative disease: Modulation of TREM2 impacts the regulatory kinase GSK-3β, which has a distinct role in the pathogenesis of various neurodegenerative diseases [136], and is associated with the PI3K–AKT–GSK-3β–mTOR signaling axis, a critical pathway for cellular metabolism, growth, and proliferation (Figure 3A,B).