Frank D, Mendelsohn C L, Ciccone E, Svensson K, Ohlsson R, Tycko B
Institute for Cancer Genetics and Department of Pathology, Columbia University College of Physicians and Surgeons, 630 W. 168th St., New York, New York 10032, USA.
Mamm Genome. 1999 Dec;10(12):1150-9. doi: 10.1007/s003359901182.
We previously described a gene, Ipl (Tssc3), that is expressed selectively from the maternal allele in placenta, yolk sac, and fetal liver and that maps within the imprinted domain of mouse distal Chromosome (Chr) 7/human Chr 11p15.5 (Hum Mol Genet 6, 2021, 1997). Ipl is similar to TDAG51, a gene that is involved in FAS/CD95 expression. Here we describe another gene, Tih1 (TDAG/Ipl homologue 1), with equivalent sequence similarity to Ipl. Structural prediction indicates that the products of these three genes share a central motif resembling a pleckstrin-homology (PH) domain, and TIH1 protein has weak sequence similarity to the PH-domain protein SEC7/CYTOHESIN. Like Ipl, Tih1 is a small gene with a single small intron. Tih1 maps to distal mouse Chr 1 and human Chr 1q31, chromosomal regions that have not shown evidence for imprinting and, in contrast to Ipl, Tih1 is expressed equally from both parental alleles. Ipl, Tih1, and TDAG51 have overlapping but distinct patterns of expression. Tih1 and TDAG51 are expressed in multiple fetal and adult tissues. In contrast, during early mouse development Ipl mRNA and protein are highly specific for two tissues involved in maternal/fetal exchange: visceral endoderm of the yolk sac and labyrinthine trophoblast of the placenta. These findings highlight the dominance of chromosomal context over gene structure in some examples of parental imprinting and extend previous evidence for placenta-specific expression of imprinted genes. The data also define a new subfamily of PH domain genes.
我们之前描述了一个基因Ipl（Tssc3），它在胎盘、卵黄囊和胎儿肝脏中从母本等位基因选择性表达，并且定位于小鼠远端染色体（Chr）7/人类Chr 11p15.5的印记区域内（《人类分子遗传学》6，2021，1997）。Ipl与TDAG51相似，TDAG51是一个参与FAS/CD95表达的基因。在此我们描述另一个基因Tih1（TDAG/Ipl同源物1），它与Ipl具有同等的序列相似性。结构预测表明这三个基因的产物共享一个类似于普列克底物蛋白同源（PH）结构域的中心基序，并且TIH1蛋白与PH结构域蛋白SEC7/CYTOHESIN具有较弱的序列相似性。与Ipl一样，Tih1是一个小基因，只有一个小内含子。Tih1定位于小鼠远端Chr 1和人类Chr 1q31，这些染色体区域未显示出印记证据，并且与Ipl不同，Tih1从两个亲本等位基因同等表达。Ipl、Tih1和TDAG51具有重叠但不同的表达模式。Tih1和TDAG51在多个胎儿和成年组织中表达。相比之下，在小鼠早期发育过程中，Ipl mRNA和蛋白对参与母胎交换的两个组织具有高度特异性：卵黄囊的脏内胚层和胎盘的迷路滋养层。这些发现突出了在亲本印记的一些例子中染色体背景对基因结构的主导作用，并扩展了先前关于印记基因胎盘特异性表达的证据。数据还定义了一个新的PH结构域基因亚家族。
