Tau is widely expressed in rat tissues

Area of Science:

• Neuroscience
• Cell Biology
• Biochemistry

Background:

• The microtubule-associated protein tau (tau) is a key component of paired helical filaments observed in Alzheimer's disease.
• Previously, tau was considered to be exclusively expressed in neurons.

Purpose of the Study:

• To investigate the expression patterns of tau in various rat tissues beyond the nervous system.
• To analyze tau isoform and phosphorylation states in different non-neuronal tissues.

Main Methods:

• Reverse transcriptase-coupled polymerase chain reaction (RT-PCR) was employed to detect tau mRNA expression.
• Immunoblotting techniques were used to confirm tau protein presence and analyze its characteristics.
• Phosphorylation states were assessed using Tau 1 antibody reactivity and electrophoretic mobility shifts post-dephosphorylation.

Main Results:

• Tau protein was detected in numerous rat tissues, including high levels in the heart, skeletal muscle, lung, kidney, and testis.
• Low levels of tau were found in the adrenal gland, stomach, and liver.
• Tissues exhibited distinct tau isoform expression profiles (predominantly small tau, predominantly big tau, or both).
• Significant tau phosphorylation, particularly at Ser396, was observed in many non-neural tissues.

Conclusions:

• Tau is widely expressed across various rat tissues, not limited to the nervous system.
• Non-neuronal tissues display diverse tau isoform expression and phosphorylation patterns.
• These findings necessitate a re-evaluation of tau's physiological roles in non-neuronal tissues.