Scaling dictates the decoder structure  

尺度不变性决定了解码器的结构

作　　者：Jingxiang Shen Feng Liu Chao Tang 沈靖翔;刘峰;汤超(Center for Quantitative Biology,Peking University,Beijing 100871,China;School of Physics,Peking University,Beijing 100871,China;Peking-Tsinghua Center for Life Sciences,Peking University,Beijing 100871,China)

机构地区：[1]Center for Quantitative Biology,Peking University,Beijing 100871,China [2]School of Physics,Peking University,Beijing 100871,China [3]Peking-Tsinghua Center for Life Sciences,Peking University,Beijing 100871,China

出　　处：《Science Bulletin》2022年第14期1486-1495,M0004,共11页科学通报（英文版）

基　　金：supported by the National Natural Science Foundation of China(12090053 and 32088101)。

摘　　要：Despite fluctuations in embryo size within a species,the spatial gene expression pattern and hence the embryonic structure can nonetheless maintain the correct proportion to the embryo size.This is known as the scaling phenomenon.For morphogen-induced patterning of gene expression,the positional information encoded in the local morphogen concentrations is decoded by the downstream genetic network(the decoder).In this paper,we show that the requirement of scaling sets severe constraints on the geometric structure of such a local decoder,which in turn enables deduction of mutants’behavior and extraction of regulation information without going into any molecular details.We demonstrate that the Drosophila gap gene system achieves scaling in the way consistent with our theory—the decoder geometry required by scaling correctly accounts for the observed gap gene expression pattern in nearly all maternal morphogen mutants.Furthermore,the regulation logic and the coding/decoding strategy of the gap gene system can also be revealed from the decoder geometry.Our work provides a general theoretical framework for a large class of problems where scaling output is achieved by non-scaling inputs and a local decoder,as well as a unified understanding of scaling,mutants’behavior,and gene regulation for the Drosophila gap gene system.尽管胚胎的大小总会存在波动,基因表达形成的空间图案却常常能保持正确的比例.对于由形态发生素梯度诱导的发育,即不同的形态发生素浓度被下游的基因网络映射(解码)为不同的细胞命运,本文指出了基因表达图案与胚胎大小保持正确比例的要求,可以通过对多个形态发生素的信息整合实现;但这也等价地决定了解码器的宏观结构.对某个具体生物体系,如果其正确比例是由这种机制保证的,那么就可以直接由解码器这种宏观结构推出当形态发生素梯度改变时的突变体表型,而无需涉及任何分子调控细节.果蝇的gap基因就是按照这样的方式实现了比例正确的表达图案——按上述逻辑预测的各种突变体表型与实验几乎完全一致.进一步,这一宏观图像还自然地解释了许多gap基因调控网络的结构特征,以及与动力学的联系.本文为这类“通过整合多个形态发生素梯度而保持正确比例”的发育问题提供了一个通用的理论框架,也对果蝇gap基因系统中的比例性、突变体表型和调控网络结构提供了一个统一的理解.

关 键 词：SCALING Pattern formation Drosophila gap gene Morphogen gradient Phenomenological decoder 

分 类 号：Q811.4[生物学—生物工程]