Figure 3. Colocalization of tau phosphorylated at threonine 175 (pThr175 tau) and tau phosphorylated at threonine 231 (pThr²³¹ tau).

Hippocampal neurons in chronic traumatic encephalopathy (CTE) (upper panels) demonstrate colocalization of pThr¹⁷⁵ tau and pThr²³¹ tau. The presence of pathologic tau oligomers (T22 immunoreactivity) was colocalized to pThr²³¹ tau-immunoreactive neurons in CTE (middle panels). Consistent with a role in activation of glycogen synthase kinase–3β (GSK3β) in inducing pathologic tau deposition, we observed the colocalization of pThr¹⁷⁵tau with the active pGSK3β immunoreactivity (lower panel). Tissues were immunolabeled with rabbit anti-pThr¹⁷⁵ tau, rabbit anti-pThr²³¹ tau, rabbit anti-T22 antibody, and mouse anti-GSK3β pTyr²¹⁶ antibody. For double-labeled tissue, red channel antibodies were labeled directly with Alexa Fluor 555. Scale bar = 5 μm.