Touch sensation, which is essential for our daily life, social interactions and sexual behaviors, is mediated by mechanosensory neurons within the trigeminal (TG) and dorsal root ganglion (DRG). Despite its importance, touch sensation is poorly understood in mammals. The molecular basis of mechanosensitivity, the developmental mechanisms that generate different types of mechanosensory neurons and circuits, and their unique functions, are largely unknown. Our long-term goal is to understand, at the molecular, cellular and circuit levels, the developmental mechanisms and the function of different types of mammalian mechanosensory neurons, using mice as a model system. Previously, we discovered that a small population of mouse somatosensory neurons expressing the neurotrophic receptor tyrosine kinase Ret develops into a classic type of mammalian mechanosensory neuron, the rapidly adapting (RA) mechanoreceptors. Moreover, we established a central role for Ret in controlling the development RA mechanoreceptors and found that peripheral end organs of one subtype of RA mechanoreceptors, the Pacinian corpuscles, are not formed in Ret knock-out mice. However, the signaling targets of Ret to specify different subtypes of RA mechanoreceptors remain elusive. Interestingly, our preliminary studies have identified the ETS transcription factor Er81 as an important target of Ret signaling in the specification of Pacinian corpuscle neurons. We propose to elucidate the roles of a Ret/Er81 signaling pathway in controlling the development of Pacinian corpuscle neurons.
Aim I : Characterize the function of Er81 in Pacinian corpuscle and touch circuit formation. We will thoroughly characterize the expression of Er81 in RA mechanoreceptors using in situ hybridization and immunostaining at different developmental stages. We will also address the primary deficits of Er81 null Pacinian corpuscle neurons and use tissue specific knockout mice to determine if Er81 is required not only in neurons but also in accessory cells for Pacinian corpuscle formation. Lastly, we will address whether Er81 is required for maintenance of Pacinian corpuscles by ablating Er81 in adult mice.
Aim II : Determine how Ret regulates Er81 to control the development of Pacinian corpuscle neurons. We will examine if Ret signaling is required and/or sufficient for regulating Er81 transcription, phosphorylation and nuclear localization in Pacinian corpuscle neurons. We will also determine if Er81 is necessary and/or sufficient for mediating the Ret signaling. Finally, we will address if Ret regulates Er81 through the mitogen- activated protein kinase (MAPK) pathway. In summary, the proposed research will determine (1) if Er81 is a novel target of Ret signaling to control the development of Pacinian corpuscle neurons and (2) how Ret signaling regulates Er81 in vivo. Results from this research will greatly improve our understanding of how mammalian mechanoreceptors develop and provide insight into axonal regeneration after injuries.

Public Health Relevance

Texture and form discrimination and the perception of touch are fundamental and important for our daily lives. Our study aims to reveal a novel molecular genetic program directing the development of one subtype of somatosensory neurons implicated in discriminative touch sensation. Insights from this study will be useful for guiding future strategies directed at promoting nerve regeneration after injuries.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS083702-02
Application #
8658495
Study Section
Neurodifferentiation, Plasticity, and Regeneration Study Section (NDPR)
Program Officer
Mamounas, Laura
Project Start
2013-07-01
Project End
2018-06-30
Budget Start
2014-07-01
Budget End
2015-06-30
Support Year
2
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of Pennsylvania
Department
Neurosciences
Type
Schools of Medicine
DUNS #
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Parmhans, Nadia; Sajgo, Szilard; Niu, Jingwen et al. (2018) Characterization of retinal ganglion cell, horizontal cell, and amacrine cell types expressing the neurotrophic receptor tyrosine kinase Ret. J Comp Neurol 526:742-766
Kridsada, Kim; Niu, Jingwen; Haldipur, Parthiv et al. (2018) Roof Plate-Derived Radial Glial-like Cells Support Developmental Growth of Rapidly Adapting Mechanoreceptor Ascending Axons. Cell Rep 23:2928-2941
Olson, William; Luo, Wenqin (2018) Somatotopic organization of central arbors from nociceptive afferents develops independently of their intact peripheral target innervation. J Comp Neurol 526:3058-3065
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Olson, William; Abdus-Saboor, Ishmail; Cui, Lian et al. (2017) Sparse genetic tracing reveals regionally specific functional organization of mammalian nociceptors. Elife 6:
Yu, Yiqun; Moberly, Andrew H; Bhattarai, Janardhan P et al. (2017) The Stem Cell Marker Lgr5 Defines a Subset of Postmitotic Neurons in the Olfactory Bulb. J Neurosci 37:9403-9414
Fleming, Michael S; Li, Jian J; Ramos, Daniel et al. (2016) A RET-ER81-NRG1 Signaling Pathway Drives the Development of Pacinian Corpuscles. J Neurosci 36:10337-10355
Olson, William; Dong, Peter; Fleming, Michael et al. (2016) The specification and wiring of mammalian cutaneous low-threshold mechanoreceptors. Wiley Interdiscip Rev Dev Biol 5:389-404
Cui, Lian; Miao, Xuerong; Liang, Lingli et al. (2016) Identification of Early RET+ Deep Dorsal Spinal Cord Interneurons in Gating Pain. Neuron 91:1137-1153
Fleming, Michael S; Vysochan, Anna; Paixão, S?nia et al. (2015) Cis and trans RET signaling control the survival and central projection growth of rapidly adapting mechanoreceptors. Elife 4:e06828

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