Contrasting DNA-binding behaviour by ISL1 and LHX3 underpins differential gene targeting in neuronal cell specification

Ngaio C Smith; Lorna E Wilkinson-White; Ann H Y Kwan; Jill Trewhella; Jacqueline M Matthews

doi:10.1016/j.yjsbx.2020.100043

Contrasting DNA-binding behaviour by ISL1 and LHX3 underpins differential gene targeting in neuronal cell specification

J Struct Biol X. 2020 Dec 15:5:100043. doi: 10.1016/j.yjsbx.2020.100043. eCollection 2021.

Authors

Ngaio C Smith¹, Lorna E Wilkinson-White², Ann H Y Kwan^{1

3}, Jill Trewhella¹, Jacqueline M Matthews¹

Affiliations

¹ School of Life and Environmental Sciences, University of Sydney, NSW 2006, Australia.
² Sydney Analytical Core Research Facility, University of Sydney, NSW 2006, Australia.
³ The University of Sydney Nano Institute, University of Sydney, NSW 2006, Australia.

Abstract

The roles of ISL1 and LHX3 in the development of spinal motor neurons have been well established. Whereas LHX3 triggers differentiation into interneurons, the additional expression of ISL1 in developing neuronal cells is sufficient to redirect their developmental trajectory towards spinal motor neurons. However, the underlying mechanism of this action by these transcription factors is less well understood. Here, we used electrophoretic mobility shift assays (EMSAs) and surface plasmon resonance (SPR) to probe the different DNA-binding behaviours of these two proteins, both alone and in complexes mimicking those found in developing neurons, and found that ISL1 shows markedly different binding properties to LHX3. We used small angle X-ray scattering (SAXS) to structurally characterise DNA-bound species containing ISL1 and LHX3. Taken together, these results have allowed us to develop a model of how these two DNA-binding modules coordinate to regulate gene expression and direct development of spinal motor neurons.

Keywords: DNA-binding specificity; Homeodomain-DNA interaction; LIM-homeodomain transcription factors; SAXS; Transcriptional complex.