Artemin overexpression in skin enhances expression of TRPV1 and TRPA1 in cutaneous sensory neurons and leads to behavioral sensitivity to heat and cold.
Artemin, a neuronal survival factor in the glial cell line-derived neurotrophic factor family, binds the glycosylphosphatidylinositol-anchored protein GFRalpha3 and the receptor tyrosine kinase Ret. Expression of the GFRalpha3 receptor is primarily restricted to the peripheral nervous system and is found in a subpopulation of nociceptive sensory neurons of the dorsal root ganglia (DRGs) that coexpress the Ret and TrkA receptor tyrosine kinases and the thermosensitive channel TRPV1. To determine how artemin affects sensory neuron properties, transgenic mice that overexpress artemin in skin keratinocytes (ART-OE mice) were analyzed. Expression of artemin caused a 20.5% increase in DRG neuron number and increased the level of mRNA encoding GFRalpha3, TrkA, TRPV1, and the putative noxious cold-detecting channel TRPA1. Nearly all GFRalpha3-positive neurons expressed TRPV1 immunoreactivity, and most of these neurons were also positive for TRPA1. Interestingly, acid-sensing ion channel (ASIC) 1, 2a, 2b, and 3 mRNAs were decreased in the DRG, and this reduction was strongest in females. Analysis of sensory neuron physiological properties using an ex vivo preparation showed that cutaneous C-fiber nociceptors of ART-OE mice had reduced heat thresholds and increased firing rates in response to a heat ramp. No change in mechanical threshold was detected. Behavioral testing of ART-OE mice showed that they had increased sensitivity to both heat and noxious cold. These results indicate that the level of artemin in the skin modulates gene expression and response properties of afferents that project to the skin and that these changes lead to behavioral sensitivity to both hot and cold stimuli.
Elitt
Christopher M
CM
Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA.
McIlwrath
Sabrina L
SL
Lawson
Jeffery J
JJ
Malin
Sacha A
SA
Molliver
Derek C
DC
Cornuet
Pamela K
PK
Koerber
H Richard
HR
Davis
Brian M
BM
Albers
Kathryn M
KM
D062565:Acid Sensing Ion Channels; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D015415:Biomarkers / Q000378:metabolism; D002211:Capsaicin / Q000494:pharmacology; D002452:Cell Count; D003080:Cold Temperature; D005260:Female; D017950:Ganglia, Sensory / Q000166:cytology; D051097:Glial Cell Line-Derived Neurotrophic Factor Receptors / Q000378:metabolism; D006358:Hot Temperature; D006984:Hypertrophy; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009475:Neurons, Afferent / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D012727:Sex Characteristics; D012867:Skin / Q000294:innervation* / Q000378:metabolism; D015222:Sodium Channels / Q000235:genetics; D000074025:TRPA1 Cation Channel; D050916:TRPV Cation Channels / Q000235:genetics / Q000378:metabolism*; D013696:Temperature; D013823:Thermoreceptors / Q000502:physiology; D050051:Transient Receptor Potential Channels / Q000378:metabolism*
C568267:ASIC1 protein, mouse; D062565:Acid Sensing Ion Channels; C116599:Artn protein, mouse; D015415:Biomarkers; C494994:Gfra3 protein, mouse; D051097:Glial Cell Line-Derived Neurotrophic Factor Receptors; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D015222:Sodium Channels; D000074025:TRPA1 Cation Channel; D050916:TRPV Cation Channels; C493921:TRPV1 protein, mouse; D050051:Transient Receptor Potential Channels; C475685:Trpa1 protein, mouse; D002211:Capsaicin