Related Experiment Video
Updated: May 31, 2026
In Vitro Aggregation Assays Using Hyperphosphorylated Tau Protein
Published on: January 2, 2015
Potentiation of tau aggregation by cdk5 and GSK3β
Sangmook Lee1, Garth F Hall, Thomas B Shea
1Center for Cellular Neurobiology and Neurodegeneration Research, Department of Biological Sciences, University of Massachusetts Lowell, Lowell, MA, USA.
Abstract:
Hyperphosphorylation of tau is closely associated with its aggregation by as yet undefined mechanisms. We attempted herein to further investigate the interrelationships between tau aggregation and phosphorylation by inhibition and activation of cdk5 and GSK3β in cells expressing normal tau and a mutant form of tau (3PO-tau), which generates intracellular aggregates while retaining microtubule-binding capacity). Aggregates were routinely observed in cells expressing 3PO-tau, but never in cells expressing normal tau, whether or not cdk5 or GSK3β was overexpressed. In addition, in cells expressing 3PO-tau, both the percentage of cells with aggregates, as well as the size of aggregates, was increased following overexpression of cdk5 or GSK3β, decreased following treatment with pharmacological agents (roscovitine and lithium) active against these kinases, and increased following treatment with the phosphatase inhibitor okadaic acid. These findings collectively indicate that phosphorylation potentiates aggregation in the presence of one or more key tau mutations. These findings confirm and extend prior studies in which overexpression of the cdk5 activator p35, or GSK3β, induced phosphorylation, mislocalization and/or aggregation of tau.
Insights
This study investigates how tau phosphorylation affects its aggregation. Findings show that increased phosphorylation, driven by kinases like cdk5 and GSK3β, potentiates tau aggregation, especially in the presence of tau mutations.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Hyperphosphorylation of tau is linked to tau aggregation, a hallmark of neurodegenerative diseases.
- The precise mechanisms connecting tau phosphorylation and aggregation remain incompletely understood.
Purpose of the Study:
- To investigate the relationship between tau aggregation and phosphorylation.
- To examine the roles of cyclin-dependent kinase 5 (cdk5) and glycogen synthase kinase 3 beta (GSK3β) in tau phosphorylation and aggregation.
Main Methods:
- Utilized cell models expressing normal tau and a mutant form (3PO-tau).
- Manipulated the activity of cdk5 and GSK3β through overexpression and pharmacological inhibition (roscovitine, lithium).
- Assessed tau aggregation using a phosphatase inhibitor (okadaic acid).
Main Results:
- Intracellular tau aggregates were observed in cells expressing 3PO-tau but not normal tau.
- Overexpression of cdk5 or GSK3β increased the percentage and size of tau aggregates in 3PO-tau cells.
- Pharmacological inhibition of these kinases decreased aggregate formation.
- Treatment with okadaic acid increased tau aggregation.
Conclusions:
- Tau phosphorylation potentiates tau aggregation, particularly when specific tau mutations are present.
- cdk5 and GSK3β play significant roles in mediating tau phosphorylation-driven aggregation.
Related Concept Videos
02:34Inhibition of Cdk Activity
02:39Positive Regulator Molecules