FRTL-5 Rat Thyroid Cells Release Thyroglobulin Sequestered in Exosomes: A Possible Novel Mechanism for Thyroglobulin Processing in the Thyroid

Figure 4

SDS-PAGE and Western blotting of samples from different stages of exosome isolation by ultracentrifugation: 17,000 ×g supernatant, 200,000 ×g supernatant, and 200,000 ×g (exosome pellet) from samples of 5H (lanes 1–6) and 6H media (lanes 7–12) collected from confluent cultures of FRTL-5 cells incubated for 48 hours. Western blots were treated with a monoclonal anti-CD9 antibody and developed using SuperSignal West Femto. All exosome samples contained 15 μL of resuspended pellet from the 200,000 ×g ultracentrifugation. 5H samples exhibited small, barely detectable bands for CD9 though some CD9 was present, while 6H samples exhibited much stronger CD9 signals indicating larger amounts of exosomes. “Exos” = exosomes (i.e., 200,000 ×g pellet).