The transthyretin gene is expressed in Schwann cells of peripheral nerves

Transthyretin (TTR) is mainly expressed in the liver and choroid plexus of the brain. The majority of familial amyloidotic polyneuropathy cases are caused by a mutant TTR gene. The origin of the TTR deposited in the peripheral nervous system is unknown. We studied the expression of TTR in the peripheral nerves of normal mice and transgenics bearing the human mutant TTR in a mouse Ttr-null background. Using RT-PCR, Ttr and TTR mRNA was observed in both dorsal root ganglia and sciatic nerves. Ttr mRNA was detected in cultured mouse Schwann cells and the immortalized mouse Schwann cell line, IMS32 cells. Human TTR mRNA and protein were detected in cultured Schwann cells derived from the transgenic mice. We conclude that the TTR gene is expressed in the Schwann cells of peripheral nerves.