ISL1-based LIM complexes control Slit2 transcription in developing cranial motor neurons

• Published in: Scientific reports Vol. 6; no. 1; p. 36491
• Main Authors: Kim, Kyung-Tai, Kim, Namhee, Kim, Hwan-Ki, Lee, Hojae, Gruner, Hannah N., Gergics, Peter, Park, Chungoo, Mastick, Grant S., Park, Hae-Chul, Song, Mi-Ryoung
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 07-11-2016; Nature Publishing Group
• Subjects: 13/109; 38/32; 38/61; 631/136/368/2430; 631/378/2571/1696; 631/378/2571/2576; 64/60; Animals; Axon guidance; Axonogenesis; Axons - physiology; Cell Differentiation - genetics; Cell lines; DNA microarrays; Gene Expression Regulation, Developmental - genetics; Homeobox; Humanities and Social Sciences; Intercellular Signaling Peptides and Proteins - genetics; Interneurons; Interneurons - physiology; Islet-1 protein; LIM-Homeodomain Proteins - genetics; Mice; Mice, Inbred C57BL; Motor neurons; Motor Neurons - physiology; Motor task performance; multidisciplinary; Nerve Tissue Proteins - genetics; Neurogenesis - genetics; Neurons; Rodents; Science; Skull; Transcription factors; Transcription Factors - genetics; Transcription, Genetic - genetics; Trigeminal Motor Nucleus - physiology
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep36491

LIM-homeodomain (HD) transcription factors form a multimeric complex and assign neuronal subtype identities, as demonstrated by the hexameric ISL1-LHX3 complex which gives rise to somatic motor (SM) neurons. However, the roles of combinatorial LIM code in motor neuron diversification and their subsequent differentiation is much less well understood. In the present study, we demonstrate that the ISL1 controls postmitotic cranial branchiomotor (BM) neurons including the positioning of the cell bodies and peripheral axon pathfinding. Unlike SM neurons, which transform into interneurons, BM neurons are normal in number and in marker expression in
Isl1
mutant mice. Nevertheless, the movement of trigeminal and facial BM somata is stalled, and their peripheral axons are fewer or misrouted, with ectopic branches. Among genes whose expression level changes in previous ChIP-seq and microarray analyses in
Isl1
-deficient cell lines, we found that
Slit2
transcript was almost absent from BM neurons of
Isl1
mutants. Both ISL1-LHX3 and ISL1-LHX4 bound to the
Slit2
enhancer and drove endogenous
Slit2
expression in SM and BM neurons. Our findings suggest that combinations of ISL1 and LHX factors establish cell-type specificity and functional diversity in terms of motor neuron identities and/or axon development.