The cellular basis of mechanosensory Merkel-cell innervation during development

• Published in: eLife Vol. 8
• Main Authors: Jenkins, Blair A, Fontecilla, Natalia M, Lu, Catherine P, Fuchs, Elaine, Lumpkin, Ellen A
• Format: Journal Article
• Language: English
• Published: England eLife Science Publications, Ltd 22.02.2019; eLife Sciences Publications Ltd; eLife Sciences Publications, Ltd
• Subjects: Animals; Bai Ling; Body Patterning; Bone Morphogenetic Protein 4 - analysis; Bone morphogenetic proteins; Cognitive development; Developmental Biology; dorsal root ganglion; Embryos; Epidermal Cells - physiology; Follicles; Hair; hair follicle; Innervation; Keratin; Keratinocytes; Keratinocytes - physiology; Keratins - analysis; Localization; mechanoreceptor; Merkel Cells - physiology; Mice; Neurons; Neuroscience; Noggin protein; Pattern formation; Peripheral Nerves - embryology; Skin; Skin - embryology; somatosensory neuron; Tactile stimuli; touch; Transcription factors; New York; United States > US; mouse; mechanoreceptor; developmental biology; neuroscience; dorsal root ganglion; skin; hair follicle; touch; somatosensory neuron
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/eLife.42633

Touch sensation is initiated by mechanosensory neurons that innervate distinct skin structures; however, little is known about how these neurons are patterned during mammalian skin development. We explored the cellular basis of touch-receptor patterning in mouse touch domes, which contain mechanosensory Merkel cell-neurite complexes and abut primary hair follicles. At embryonic stage 16.5 (E16.5), touch domes emerge as patches of Merkel cells and keratinocytes clustered with a previously unsuspected population of -expressing dermal cells. Epidermal Noggin overexpression at E14.5 disrupted touch-dome formation but not hair-follicle specification, demonstrating a temporally distinct requirement for BMP signaling in placode-derived structures. Surprisingly, two neuronal populations preferentially targeted touch domes during development but only one persisted in mature touch domes. Finally, Keratin-17-expressing keratinocytes but not Merkel cells were necessary to establish innervation patterns during development. These findings identify key cell types and signaling pathways required for targeting Merkel-cell afferents to discrete mechanosensory compartments.