Amarger Valérie, Nguyen Minh, Van Laere Anne-Sophie, Braunschweig Martin, Nezer Carine, Georges Michel, Andersson Leif
Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Box 597, SE-751 24 Uppsala, Sweden.
Mamm Genome. 2002 Jul;13(7):388-98. doi: 10.1007/s00335-001-3059-x.
IGF2 is the major candidate gene for a paternally expressed Quantitative Trait Locus (QTL) in the pig primarily affecting muscle development. Here we report two sequence contigs together comprising almost 90 kb containing the INS-IGF2 and H19 genes. A comparative sequence analysis of the pig, human, and mouse genomic sequences was conducted to identify the exon/intron organization, all promoters, and other evolutionarily conserved elements. RT-PCR analysis showed that IGF2 transcripts originated from four different promoters and included various combinations of seven untranslated exons together with three coding exons, in agreement with previous findings in other mammals. The observed sequence similarity in intronic and intragenic regions among the three species is remarkable and is most likely explained by the complicated regulation of imprinting and expression of these genes. The general trend was, as expected, a higher sequence similarity between human and pig than between these species and the mouse, but a few exceptions to this rule were noted. This genomic region exhibits several striking features, including a very high GC content, many CpG islands, and a low amount of interspersed repeats. The high GC and CpG content were more pronounced in the pig than in the two other species. The results will facilitate the further characterization of this important QTL in the pig.
胰岛素样生长因子2（IGF2）是猪中一个主要受父系表达的数量性状基因座（QTL）的主要候选基因，该QTL主要影响肌肉发育。在此，我们报告了两个序列重叠群，它们共同构成了近90 kb的区域，包含胰岛素基因（INS）-胰岛素样生长因子2基因（IGF2）和H19基因。对猪、人类和小鼠的基因组序列进行了比较序列分析，以确定外显子/内含子结构、所有启动子以及其他进化保守元件。逆转录聚合酶链反应（RT-PCR）分析表明，IGF2转录本源自四个不同的启动子，包括七个非翻译外显子与三个编码外显子的各种组合，这与先前在其他哺乳动物中的研究结果一致。在这三个物种的内含子和基因内区域观察到的序列相似性非常显著，很可能是由这些基因复杂的印记和表达调控所解释。正如预期的那样，一般趋势是人与猪之间的序列相似性高于人与小鼠之间的相似性，但也注意到了一些该规则的例外情况。这个基因组区域呈现出几个显著特征，包括非常高的GC含量、许多CpG岛以及少量的散布重复序列。猪中的高GC和CpG含量比另外两个物种更为明显。这些结果将有助于进一步鉴定猪中这个重要的QTL。
