Gyoja Fuki, Satoh Nori
Marine Genomics Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa 904-0495, Japan.
Zoolog Sci. 2013 Oct;30(10):868-76. doi: 10.2108/zsj.30.868.
Basic helix-loop-helix (bHLH) transcription factors play significant roles in multiple biological processes in metazoan cells. In recent work, we showed that three orthologous HLH families, pearl, amber, and peridot, have apparently been lost in the Drosophila melanogaster, Caenorhabditis elegans, and Homo sapiens lineages. To further address the gain and loss of bHLH proteins during bilaterian evolution, we examined the genome of the pearl oyster, Pinctada fucata, which has recently been sequenced. We characterized the putative full set 65 bHLH genes and showed that genes previously categorized into the orthologous family PTFb, actually fall into two distinct orthologous families, 48-related-1 and 48-related-2. We also identified a novel orthologous family, clockwork orange. Based on these newly identified orthologous family members and on orphan bHLH factors, we propose that genes encoding bHLH factors in bilaterians are not as evolutionarily stable as previously thought.
基本螺旋-环-螺旋（bHLH）转录因子在多细胞动物细胞的多种生物学过程中发挥着重要作用。在最近的研究中，我们发现果蝇、秀丽隐杆线虫和人类谱系中三个直系同源的HLH家族，即珍珠、琥珀和橄榄石家族，显然已经丢失。为了进一步探讨两侧对称动物进化过程中bHLH蛋白的获得与丢失情况，我们研究了最近已测序的珍珠牡蛎（Pinctada fucata）的基因组。我们鉴定了假定的65个bHLH基因全集，并表明先前归类为直系同源家族PTFb的基因实际上分为两个不同的直系同源家族，即48相关-1和48相关-2。我们还鉴定了一个新的直系同源家族，即发条橙。基于这些新鉴定的直系同源家族成员和孤儿bHLH因子，我们提出两侧对称动物中编码bHLH因子的基因在进化上并不像以前认为的那样稳定。
