TY - JOUR T1 - Visualized procollagen Iα1 demonstrates the intracellular processing of propeptides JF - Life Science Alliance JO - Life Sci. Alliance DO - 10.26508/lsa.202101060 VL - 5 IS - 5 SP - e202101060 AU - Toshiaki Tanaka AU - Koji Moriya AU - Makoto Tsunenaga AU - Takayo Yanagawa AU - Hiromi Morita AU - Takashi Minowa AU - Yoh-ichi Tagawa AU - Nobutaka Hanagata AU - Yutaka Inagaki AU - Toshiyuki Ikoma Y1 - 2022/05/01 UR - https://www.life-science-alliance.org/content/5/5/e202101060.abstract N2 - The processing of type I procollagen is essential for fibril formation; however, the steps involved remain controversial. We constructed a live cell imaging system by inserting fluorescent proteins into type I pre-procollagen α1. Based on live imaging and immunostaining, the C-propeptide is intracellularly cleaved at the perinuclear region, including the endoplasmic reticulum, and subsequently accumulates at the upside of the cell. The N-propeptide is also intracellularly cleaved, but is transported with the repeating structure domain of collagen into the extracellular region. This system makes it possible to detect relative increases and decreases in collagen secretion in a high-throughput manner by assaying fluorescence in the culture medium, and revealed that the rate-limiting step for collagen secretion occurs after the synthesis of procollagen. In the present study, we identified a defect in procollagen processing in activated hepatic stellate cells, which secrete aberrant collagen fibrils. The results obtained demonstrated the intracellular processing of type I procollagen, and revealed a link between dysfunctional processing and diseases such as hepatic fibrosis. ER -