论文标题
具有双重GTPase开关的信号传导电路的稳定性分析
Stability analysis of a signaling circuit with dual species of GTPase switches
论文作者
论文摘要
GTPase是分子开关,可调节广泛的细胞过程,例如细胞器生物发生,位置,形状和信号转导。这些酶是通过在三磷酸(GTP)构成状态的活性(“ on”)鸟苷之间切换的,而二磷酸鸟苷(GDP) - 抑制剂状态;这种拨动由GEFS(GUANINE核苷酸交换因子)和GAP(GTPase激活蛋白)调节。在这里,我们在多细胞生物的真核细胞中剖析单体(M)和三聚体(T)GTPases之间的网络基序。为此,我们开发了一个普通微分方程的系统,在该系统中,这两类的GTPases通过前馈和反馈循环在主题中与其开/关状态相互链接。我们为系统的稳态提供公式,并执行局部稳定性分析,以研究GTPase开关之间不同连接的作用。从活性MGTPase到TGTPase的GEF的饲料足以提供两个局部稳定的状态:一种可以将MGTPase的活性/非活动形式解释为具有低浓度,而M-和TGTPase均具有高浓度。当从TGTPase的GEF到MGTPase的间隙的反馈回路被添加到FeedForward系统中时,出现了另外两个局部稳定的状态,均已灭活TGTPase并被解释为具有低活性TGTPase浓度。最后,从活动TGTPase到MGTPase的间隙增加了第二个反馈回路,从而产生了一个由无效TGTPase浓度参数参数化的稳态家族。我们的发现表明,这两个不同的GTPase基序的耦合可以极大地改变其稳态行为,并阐明这种耦合如何影响真核细胞中的信息处理。
GTPases are molecular switches that regulate a wide range of cellular processes, such as organelle biogenesis, position, shape, and signal transduction. These enzymes operate by toggling between an active ("ON") guanosine triphosphate (GTP)-bound state and an inactive ("OFF") guanosine diphosphate (GDP)-bound state; such a toggle is regulated by GEFs (guanine nucleotide exchange factors) and GAPs (GTPase activating proteins). Here we dissect a network motif between monomeric (m) and trimeric (t) GTPases assembled exclusively in eukaryotic cells of multicellular organisms. To this end, we develop a system of ordinary differential equations in which these two classes of GTPases are interlinked conditional to their ON/OFF states within a motif through feedforward and feedback loops. We provide formulas for the steady states of the system and perform local stability analysis to investigate the role of the different connections between the GTPase switches. A feedforward from the active mGTPase to the GEF of the tGTPase was sufficient to provide two locally stable states: one where both active/inactive forms of the mGTPase can be interpreted as having low concentrations and the other where both m- and tGTPase have high concentrations. When a feedback loop from the GEF of the tGTPase to the GAP of the mGTPase was added to the feedforward system, two other locally stable states emerged, both having the tGTPase inactivated and being interpreted as having low active tGTPase concentrations. Finally, the addition of a second feedback loop, from the active tGTPase to the GAP of the mGTPase, gives rise to a family of steady states parametrized by the inactive tGTPase concentrations. Our findings reveal that the coupling of these two different GTPase motifs can dramatically change their steady state behaviors and shed light on how such coupling may impact information processing in eukaryotic cells.