PT - JOURNAL ARTICLE 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 TI - Visualized procollagen Iα1 demonstrates the intracellular processing of propeptides AID - 10.26508/lsa.202101060 DP - 2022 May 01 TA - Life Science Alliance PG - e202101060 VI - 5 IP - 5 4099 - https://www.life-science-alliance.org/content/5/5/e202101060.short 4100 - https://www.life-science-alliance.org/content/5/5/e202101060.full SO - Life Sci. Alliance2022 May 01; 5 AB - 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.