Establishment of proprotein convertase, furinA knocked-out lines in medaka, Oryzias latipes, and unique form of medaka furin-like prorprotein convertase (mflPC).

Furin is a member of the subtilisin-like proprotein convertase family. Medaka furin-like proprotein convertase (mflPC), a unique form of medaka FurinA (mFurinA) (GenBank accession no. AB092685.1) was cloned from the ovary cDNA library. Compared to human furin (GenBank accession no. NM_002569.3) and mFurinA in the structural motif of mflPC, only the catalytic domain and the N-terminal region of the P domain are highly conserved, but more C-terminal domains are truncated. Based on our research, there three forms of furin, mFurinA, mflPC and mFurinB that exist in medaka. These three genes are expressed in the developing embryos and ubiquitously in adult tissues. To investigate the function of mFurinA and mflPC, as a first step, mFurinA KO lines were established. The mFurinA KO larvae with abnormal phenotypes exhibit edema, abnormal body fluid accumulation in the pericardial and yolk sacs, enlarged hearts, clogged blood vessels, structurally weak eyes, and a very short life. The data suggests that abnormal processing of TGF-β may be one of the causes of these disorders. FurinA KO medaka is a good model for the study of human diseases such as Fraser Syndrome and Marfan syndrome. The creation of human genomic disorder models using recently advanced genome editing procedures informs us of the function of key molecules and their role in causing equivalent human disorders and will be useful as a tool to identify the mechanisms involved.