PROBLEM TO BE SOLVED: To provide a medicinal composition for preventing or treating Niemann-Pick disease type C (NPC), an agent for improving an abnormality in intracellular lipid transport, and a NPC preventive/therapeutic agent or a candidate substance of NPC preventive/therapeutic agent, or a method for screening an agent for improving an abnormality in intracellular lipid transport.SOLUTION: The present invention provides a novel substance for preventing or treating NPC, the substance comprising a composition comprising a ceramide-1-phosphate (C1P) production inhibitor. Here, the CIP production inhibitor is a ceramide kinase production inhibitor, a nucleic acid that specifically inhibits the expression of ceramide kinase, or a vector containing such a nucleic acid, the nucleic acid being a sRNA or antisense nucleic acid.EFFECT: In the novel substance, action mechanism of NPC treatment due to the inhibition of C1P production directly improves an intracellular abnormal lipid transport, especially an intracellular abnormal cholesterol transport. The improvement may lead to a fundamental treatment for NPC.SELECTED DRAWING: Figure 1【課題】ニーマン・ピック病Ｃ型（ＮＰＣ）を予防又は治療するための医薬組成物、細胞内脂質輸送異常改善剤、及び、ＮＰＣ予防／治療薬又はＮＰＣ予防／治療薬候補物質、又は細胞内脂質輸送異常改善剤をスクリーニングする方法の提供。【解決手段】セラミド－１－リン酸（Ｃ１Ｐ）生成阻害剤を含む、ＮＰＣを予防又は治療するための新規物質。前記ＣＩＰ生成阻外剤がセラミドキナーゼ生成阻外剤であり、セラミドキナーゼの発現を特異的に阻外する核酸、又は当該核酸を含むベクターであり、当該核酸がｓｉＲＮＡ又はアンチセンス核酸である組成物。【効果】新規物質は、Ｃ１Ｐ生成阻害によるＮＰＣ治療の作用機序は、細胞内脂質輸送異常、特に細胞内コレステロール輸送異常を直接改善するもので、ＮＰＣの根本治療につながる可能性がある。【選択図】図１
