EXPRESSION AND ACTIVITY OF THE NEWT MSX-1 GENE IN RELATION TO LIMB REGENERATION
EXPRESSION AND ACTIVITY OF THE NEWT MSX-1 GENE IN RELATION TO LIMB REGENERATION
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DOI：
10.1098/rspb.1995.0024
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发表时间：
1995-02-22
影响因子：
4.7
通讯作者：
GANN, AAF
中科院分区：
文献类型：
--
作者：
CREWS, L;GATES, PB;GANN, AAF
Msx-1同源盒基因在脊椎动物发育过程中的各种环境中表达，包括鸟类和小鼠肢芽的进展区。小鼠Msx-1在培养的肌源性细胞系中的表达赋予转化的表型并抑制融合成肌管。已经提出，Msx-1表达是维持某些细胞处于增殖和未分化状态所必需的，并且可能与肢体再生的能力有关。有尾目两栖动物如蝾螈通过形成生长区或芽基再生肢体，我们从肢体芽基cDNA文库中分离并测序了蝾螈Msx-1（NvMsx-1）。NvMsx-1的表达是可检测的RNA制剂从肢体和尾巴和他们的再生胚基，虽然培养的细胞建立肢体胚间充质给阴性结果。当COS细胞或培养的蝾螈胚细胞共转染的表达载体NvMsx-1和含有多个同源框蛋白结合位点的报告质粒，NvMsx-1抑制报告表达。如果NvMsx-1与标记酶一起在培养的蝾螈胚基细胞中表达，则相对于对照转染子，观察到DNA合成没有显著差异。当肌原性单核细胞转染NvMsx-1，随后暴露于低血清，以促进融合，在肌管中的Msx-1阳性细胞的分数是在相同的培养分析的对照转染群体相当。这些结果表明，虽然Msx-1的表达可能是重要的肢体再生，它不发挥细胞自主的作用，增殖或成肌分化培养胚细胞。
The Msx-1 homeobox gene is expressed in various contexts during vertebrate development, including the progress zone of the avian and mouse limb bud. Expression of mouse Msx-1 in a cultured myogenic cell line conferred a transformed phenotype and inhibited fusion into myotubes. It has been proposed that Msx-1 expression is required to maintain certain cells in a proliferating and undifferentiated state and may be associated with the ability to regenerate limbs. Urodele amphibians such as the newt regenerate their limbs by formation of a growth zone or blastema, and we have isolated and sequenced newt Msx-1 (NvMsx-1) from a limb blastemal cDNA library. NvMsx-1 expression was detectable in RNA preparations from both limb and tail and their regeneration blastemas, although cultured cells established from limb blastemal mesenchyme gave negative results. When either COS cells or cultured newt blastemal cells were cotransfected with an expression vector for NvMsx-1 and reporter plasmids containing multiple homeobox protein binding sites, NvMsx-1 repressed reporter expression. If NvMsx-1 was expressed together with a marker enzyme in cultured newt blastemal cells, no significant difference in DNA synthesis was observed relative to control transfectants. When myogenic mononucleate cells were transfected with NvMsx-1 and subsequently exposed to low serum to promote fusion, the fraction of Msx-1 positive cells in myotubes was comparable to a control transfected population analysed in the same culture. These results indicate that although Msx-1 expression could be important for limb regeneration, it does not exert a cell-autonomous effect on proliferation or myogenic differentiation of cultured blastemal cells.