Gunawardhana Kushan L, Rivas Gustavo B S, Caster Courtney, Hardin Paul E
Department of Biology and Center for Biological Clocks Research, Texas A&M University, College Station, TX, USA.
iScience. 2020 Dec 7;24(1):101893. doi: 10.1016/j.isci.2020.101893. eCollection 2021 Jan 22.
The () gene encodes a transcriptional repressor required for development as well as circadian behavior in adults. Alternate first exons produce transcripts predicted to produce a short VRI isoform during development and long VRI in adults. A mutant ( ) lacking long VRI transcripts is viable, confirming that short VRI is sufficient for developmental functions, yet behavioral rhythms in flies persist, showing that short VRI is sufficient for clock output. E-box regulatory elements that drive rhythmic long VRI transcript expression are required for developmental expression of short VRI transcripts. Surprisingly, long VRI transcripts primarily produce short VRI in adults, apparently due to a poor Kozak sequence context, demonstrating that short VRI drives circadian behavior. Thus, E-box-driven long VRI transcripts primarily control circadian rhythms via short VRI, whereas the same E-boxes drive short VRI transcripts that control developmental functions using short VRI.
（）基因编码一种转录抑制因子，它是成虫发育以及昼夜节律行为所必需的。不同的首个外显子产生的转录本预计在发育过程中产生短的VRI异构体，而在成虫中产生长的VRI。缺乏长VRI转录本的突变体（）是可行的，这证实了短VRI足以实现发育功能，但果蝇的行为节律仍然存在，表明短VRI足以实现时钟输出。驱动有节律的长VRI转录本表达的E-box调控元件是短VRI转录本发育表达所必需的。令人惊讶的是，长VRI转录本在成虫中主要产生短VRI，显然是由于较差的科扎克序列环境，这表明短VRI驱动昼夜节律行为。因此，E-box驱动的长VRI转录本主要通过短VRI控制昼夜节律，而相同的E-box驱动短VRI转录本利用短VRI控制发育功能。
