Overexpressed LIM mineralization proteins do not require LIM domains to induce bone
Overexpressed LIM mineralization proteins do not require LIM domains to induce bone
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DOI：
10.1359/jbmr.2002.17.3.406
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发表时间：
2002-03-01
影响因子：
6.2
通讯作者：
Titus, L
中科院分区：
文献类型：
--
作者：
Liu, YS;Hair, GA;Titus, L
大鼠LIM矿化蛋白1（LMP-1，LIM结构域蛋白）介导骨形态发生蛋白6（BMP-6）诱导胎鼠颅骨成骨细胞（ROB）培养物中骨结节形成。我们已经从成人心脏cDNA文库中分离出LMP-1的人类同源物的互补DNA（cDNA），并表明当过表达时，它在相同的培养系统中具有骨诱导性。最近修订的Enigma的cDNA序列，其蛋白质产物与胰岛素受体和酪氨酸激酶受体ret结合，现在与人LMP-1（hLMP-1）的核苷酸序列相匹配。截短的223个氨基酸（AA）LMP-1（t）蛋白具有与全长蛋白相同的作用，尽管缺失了LIM结构域。已检测到人LMP-1的两种剪接变体。人LMP-2在bp 325和444之间具有119个碱基对（bp）缺失，并且在bp 444处具有17个碱基对插入。所得衍生蛋白含有423个AA，LIM结构域完整，并且在ROB培养物中过表达时不诱导骨形成。人LMP-3在bp 444处具有相同的17个核苷酸插入，导致阅读框的移位，其导致终止密码子出现在bp 505 - 507处。所得的153 AA蛋白不具有LIM结构域，但hLMP-3的过表达诱导成骨细胞培养物中的骨形成。这些发现表明LIM结构域不是LMP诱导骨形成所必需的。此外，骨形成可能需要LMP-1蛋白的一个小区域（36个AA）。
Rat LIM mineralization protein 1 (LMP-1, an LIM domain protein) mediates bone morphogenetic protein 6 (BMP-6) induction of bone nodule formation in fetal rat calvarial osteoblast (ROB) cultures. We have isolated the complementary DNA (cDNA) for the human homologue of LMP-1 from an adult human heart cDNA library and showed that when overexpressed it is osteoinductive in the same culture system. The recently, revised cDNA sequence of Enigma, the protein product of which binds to the insulin receptor and the tyrosine kinase receptor ret, now matches the nucleotide sequence of human LMP-1 (hLMP-1). A truncated, 223 amino acid (AA) LMP-1(t) protein has identical effects as the full-length protein, despite the deletion of the LIM domains. Two splice variants of human LMP-1 have been detected. Human LMP-2 has a 119-base pair (bp) deletion between bp 325 and 444 and a 17-bp insertion at bp 444. The resulting derived protein contains 423 AA with the LIM domains intact and does not induce bone formation when overexpressed in ROB cultures. Human LMP-3 has the same 17 nucleotide insertion at bp 444, resulting in a shift in the reading frame that causes a stop codon to occur at bp 505-507. The resulting 153 AA protein does not have the LIM domains, but overexpression of hLMP-3 induces bone formation in osteoblast cultures. These findings suggest that the LIM domains are not required for LMPs to induce bone formation. In addition, a small region (36 AA) of the LMP-1 protein may be required for bone formation.