A gene regulatory network for cell-type patterning in the Arabidopsis root epidermis

Extended discrete gene regulatory network model for theArabidopsis thalianaroot-hair cell fate

“…However, it has been shown that the MBW complex positively regulates MYB23 whose protein is functionally similar to WER and MYB23 directly inactivates SCM, which allows WER activation. Thus it has been suggested that MYB23 has indirect positive feedback on WER activity, but this interaction has not been analyzed in previous GRN models [59, 66, 108]. In our previous theoretical works, we proposed the existence of a positive feedback mechanism in the formation of the MBW complex [1, 11], but the nature of this interaction had not been attributed to regulation through MYB23.…”

“…It has been previously established that the S1 and S2 motifs are necessary in the structure of the CPC protein for its mobilization, being the S2 motif also necessary for its nuclear localization [64]. Thus, and given the structural and functional similarities of this protein family, it has been thought that other proteins homologous to CPC could have the ability to mobilize between cells of the epidermis and establish new feedback loops that allow giving robustness to the GRN, especially due to the conservation of the S2 motif among the various members of the family [108]. However, so far, this hypothesis has not been proven [125].…”

“…In turn, WER, as part of the MBW complex in the N-cells, inhibits the activity of SCM while CPC and TRY promote it [66]. Altogether these regulatory mechanisms establish the robust pattern of spatial cellular organization in the root epidermis of Arabidopsis thaliana [11, 108].…”

“…Moreover, it has been established that the characterized networks give rise to the dynamic structural mechanisms that determine the observed organizational pattern. Which is to say: the existence of a mechanism of lateral inhibition through the accumulation of the MBW complex that regulates the expression of diffusible molecules (CPC, TRY, and ETC1) that prevent adjacent cells from adopting the same fate through inhibitory complex activity; positive feedback loops on WER activity (through the MYB23 activity); as well as among the positional signals coming from the cortex through the SCM and JACKDAW (JKD) activity have been described [59, 100, 108, 140].…”

“…This mechanism generates concentration differences between a self-promoting activator (the MBW complex) and an inhibitor with high intercellular mobility (the IC). Along with this key pattern-forming regulatory motif, positive and negative feedback loops between WER/MYB23 and CPC as well as among the positional signals coming from the cortex have been described to date [100, 108, 140].…”