Induction and myofibrillar targeting of CARP, and suppression of the Nkx2.5 pathway in the MDM mouse with impaired titin-based signaling.
Induction and myofibrillar targeting of CARP, and suppression of the Nkx2.5 pathway in the MDM mouse with impaired titin-based signaling.
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DOI：
10.1016/j.jmb.2003.12.021
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发表时间：
2004-02
影响因子：
5.6
通讯作者：
C. Witt;Y. Ono;E. Puschmann;M. Mcnabb;Yiming Wu;M. Gotthardt;S. Witt;M. Haak;D. Labeit;C. Gregorio;H. Sorimachi;H. Granzier;S. Labeit
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文献类型：
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作者：
C. Witt;Y. Ono;E. Puschmann;M. Mcnabb;Yiming Wu;M. Gotthardt;S. Witt;M. Haak;D. Labeit;C. Gregorio;H. Sorimachi;H. Granzier;S. Labeit
肌萎缩症伴肌炎（mdm）是一种隐性小鼠突变，由大弹性肌蛋白titin的小缺失引起。纯合子mdm/mdm小鼠会出现进行性肌肉萎缩症，导致2个月大时死亡。我们调查了24日龄纯合子mdm/mdm和+/+野生型小鼠骨骼肌的转录组，这是mdm动物具有正常被动和主动张力和肌肉结构的年龄。在12488个基因中（U74 affymetrix阵列），75个基因的差异表达为2 - 30倍，包括CARP （cardiac ankyrin repeat protein）、ankrd2/Arpp （CARP样蛋白）和MLP (muscle LIM protein)，它们都与titin - filament system相关。受影响最强烈的4个基因（8 - 30倍变化）均为CARP调控的nkx -2.5依赖信号通路的成员，MDM骨骼肌组织中CARP mRNA水平升高30倍。MDM中过表达的CARP蛋白与肌节的i带区相关。mdm突变切除了titin的N2A区域的c端部分，取消了它与p94/calpain-3蛋白酶的相互作用。因此，在MDM中，titin N2A蛋白复合物的组成因CARP的掺入和p94/calpain-3的丢失而发生改变。这些变化在以下对照组织(1)纯合子mdm/mdm动物的心肌，(2)杂合子mdm/+动物的骨骼肌和心肌，以及(3)MDX小鼠的营养不良肌肉中没有出现。因此，titin N2A复合物组成的改变是MDM中以titin为基础的骨骼肌营养不良所特有的。
Muscular dystrophy with myositis (mdm) is a recessive mouse mutation that is caused by a small deletion in the giant elastic muscle protein titin. Homozygous mdm/mdm mice develop a progressive muscular dystrophy, leading to death at ∼2 months of age. We surveyed the transcriptomes of skeletal muscles from 24 day old homozygous mdm/mdm and +/+ wild-type mice, an age when MDM animals have normal passive and active tensions and sarcomeric structure. Of the 12,488 genes surveyed (U74 affymetrix array), 75 genes were twofold to 30-fold differentially expressed, including CARP (cardiac ankyrin repeat protein), ankrd2/Arpp (a CARP-like protein) and MLP (muscle LIM protein), all of which associate with the titin filament system. The four genes most strongly affected (eightfold to 30-fold change) were all members of the CARP-regulated Nkx-2.5-dependent signal pathway, and CARP mRNA level was 30-fold elevated in MDM skeletal muscle tissues. The CARP protein overexpressed in MDM became associated with the I-band region of the sarcomere. The mdm mutation excises the C-terminal portion of titin's N2A region, abolishing its interaction with p94/calpain-3 protease. Thus, the composition of the titin N2A protein complex is altered in MDM by incorporation of CARP and loss of p94/calpain-3. These changes were absent from the following control tissues (1) cardiac muscles from homozygous mdm/mdm animals, (2) skeletal and cardiac muscle from heterozygous mdm/+ animals, and (3) dystrophic muscles from MDX mice. Thus, the altered composition of the titin N2A complex is specific for the titin-based skeletal muscular dystrophy in MDM.