A nonsense mutation in cGMP-dependent type II protein kinase (PRKG2) causes dwarfism in American Angus cattle
A nonsense mutation in cGMP-dependent type II protein kinase (PRKG2) causes dwarfism in American Angus cattle
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DOI：
10.1073/pnas.0904513106
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发表时间：
2009-11-17
影响因子：
11.1
通讯作者：
Reecy, James M.
中科院分区：
文献类型：
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作者：
Koltes, James E.;Mishra, Bishnu P.;Reecy, James M.
从历史上看，侏儒症是美国人的主要遗传缺陷。S.肉牛积极的淘汰和父系测试，以尽量减少其患病率，但是，这些做法都不能消除隐性遗传缺陷。我们收集了一个4代系谱，以确定美国安格斯牛侏儒症的突变基础。Elston-Steward算法的适应用于克服小谱系大小和缺失基因型。矮秆基因座被精细定位在标记AFR 227和BM 4311之间的BTA 6上。对4个候选基因进行测序，发现cGMP依赖的II型蛋白激酶（PRKG 2）第15外显子存在无义突变。该C/T转换引入了终止密码子（R678 X），其截短了85个C末端氨基酸，包括激酶结构域的大部分。在该区域发现的75个突变中，只有该突变与受影响和携带者个体中的隐性遗传模式100%一致（比值分数的对数= 6.63）。先前的研究表明，PRKG 2调节SRY（性别决定区Y）盒9（SOX 9）介导的胶原2（COL 2）转录。我们评估了野生型（WT）或R678 X PRKG 2调节细胞培养物中COL 2表达的能力。实时PCR结果证实，与WT PRKG 2相比，COL 2在过表达R678 X PRKG 2的细胞中过表达。此外，COL 2和COL 10的mRNA表达增加侏儒牛相比，未受影响的牛。这些实验表明，R678 X突变是功能性的，导致PRKG 2对COL 2和COL 10 mRNA表达的调节丧失。因此，我们提出PRKG 2 R678 X作为侏儒症牛的致病突变。
Historically, dwarfism was the major genetic defect in U. S. beef cattle. Aggressive culling and sire testing were used to minimize its prevalence; however, neither of these practices can eliminate a recessive genetic defect. We assembled a 4-generation pedigree to identify the mutation underlying dwarfism in American Angus cattle. An adaptation of the Elston-Steward algorithm was used to overcome small pedigree size and missing genotypes. The dwarfism locus was fine-mapped to BTA6 between markers AFR227 and BM4311. Four candidate genes were sequenced, revealing a nonsense mutation in exon 15 of cGMP-dependant type II protein kinase (PRKG2). This C/T transition introduced a stop codon (R678X) that truncated 85 C-terminal amino acids, including a large portion of the kinase domain. Of the 75 mutations discovered in this region, only this mutation was 100% concordant with the recessive pattern of inheritance in affected and carrier individuals (log of odds score = 6.63). Previous research has shown that PRKG2 regulates SRY (sex-determining region Y) box 9 (SOX9)-mediated transcription of collagen 2 (COL2). We evaluated the ability of wild-type (WT) or R678X PRKG2 to regulate COL2 expression in cell culture. Real-time PCR results confirmed that COL2 is overexpressed in cells that overexpressed R678X PRKG2 as compared with WT PRKG2. Furthermore, COL2 and COL10 mRNA expression was increased in dwarf cattle compared with unaffected cattle. These experiments indicate that the R678X mutation is functional, resulting in a loss of PRKG2 regulation of COL2 and COL10 mRNA expression. Therefore, we present PRKG2 R678X as a causative mutation for dwarfism cattle.