miRNAs as mobile signals in development

Advisor: Marja Timmermans

Location: University of Tübingen

Microscopic images of leaf primordia with highlighted morphogen-like patterning activities of mobile small RNAs. — Figure 1. Gradients of mobile small RNAs have morphogen-like patterning activities. Mobility of miRNAs from their site of biogenesis in the bottom epidermis (A) yields a miRNA gradient (B) that through a threshold-based read-out establishes an on-off pattern of target gene expression (C, D).

Figure 1. Gradients of mobile small RNAs have morphogen-like patterning activities. Mobility of miRNAs from their site of biogenesis in the bottom epidermis (A) yields a miRNA gradient (B) that through a threshold-based read-out establishes an on-off pattern of target gene expression (C, D).

Close-ups of Arabidopsis seedlings with fluorescent reporters in their leaves. — Figure 2. Synthetic system to study miRNA mobility. In seedlings expressing fluorescent reporters (A), artificial miRNAs targeting these reporters are expressed in a regulated often tissue-specific manner (B) to arrive at the parameters and mechanisms of miRNA mobility (C)

Figure 2. Synthetic system to study miRNA mobility. In seedlings expressing fluorescent reporters (A), artificial miRNAs targeting these reporters are expressed in a regulated often tissue-specific manner (B) to arrive at the parameters and mechanisms of miRNA mobility (C)

Small RNAs act as mobile signals in several patterning processes. Reminiscent to classical morphogens, small RNAs provide positional information and generate precisely defined domains of gene expression through an intrinsic, threshold-based readout of their mobility gradients (Skopelitis et al., 2017). The cell-to-cell movement of small RNAs occurs via plasmodesmatal channels, which are gated at individual cell-cell interfaces to regulate mobility and pattern small RNA activity (Skopelitis et al., 2018). We now seek to understand how small RNAs move, how their mobility at plasmodesmata is gated, and how the threshold-based readout of mobile small RNA gradients is realized?

More information about the research of Marja Timmermans and a selection of recent publications can be found on her faculty page.

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Application deadline: 27 January 2025