title: The stress protein heat shock cognate 70 (Hsc70) inhibits the Transient Receptor Potential Vanilloid type 1 (TRPV1) channel.
abstract: Specialized cellular defense mechanisms prevent damage from chemical, biological, and physical hazards. The heat shock proteins have been recognized as key chaperones that maintain cell survival against a variety of exogenous and endogenous stress signals including noxious temperature. However, the role of heat shock proteins in nociception remains poorly understood. We carried out an expression analysis of the constitutively expressed 70 kDa heat-shock cognate protein, a member of the stress-induced HSP70 family in lumbar dorsal root ganglia from a mouse model of Complete Freund's Adjuvant-induced chronic inflammatory pain. We used immunolabeling of dorsal root ganglion neurons, behavioral analysis and patch clamp electrophysiology in both dorsal root ganglion neurons and HEK cells transfected with Hsc70 and Transient Receptor Potential Channels to examine their functional interaction in heat shock stress condition.
  
  
  
  We report an increase in protein levels of Hsc70 in mouse dorsal root ganglia, 3 days post Complete Freund's Adjuvant injection in the hind paw. Immunostaining of Hsc70 was observed in most of the dorsal root ganglion neurons, including the small size nociceptors immunoreactive to the TRPV1 channel. Standard whole-cell patch-clamp technique was used to record Transient Receptor Potential Vanilloid type 1 current after exposure to heat shock. We found that capsaicin-evoked currents are inhibited by heat shock in dorsal root ganglion neurons and transfected HEK cells expressing Hsc70 and TRPV1. Blocking Hsc70 with matrine or spergualin compounds prevented heat shock-induced inhibition of the channel. We also found that, in contrast to TRPV1, both the cold sensor channels TRPA1 and TRPM8 were unresponsive to heat shock stress. Finally, we show that inhibition of TRPV1 depends on the ATPase activity of Hsc70 and involves the rho-associated protein kinase.
  
  
  
  Our work identified Hsc70 and its ATPase activity as a central cofactor of TRPV1 channel function and points to the role of this stress protein in pain associated with neurodegenerative and/or metabolic disorders, including aging.
authors: Department of Physiology and Pharmacology and Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Canada.
authors: Mircea
authors: M
authors: Iftinca
authors: Department of Physiology and Pharmacology and Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Canada.
authors: Robyn
authors: R
authors: Flynn
authors: Department of Physiology and Pharmacology and Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Canada.
authors: Lilian
authors: L
authors: Basso
authors: Department of Physiology and Pharmacology and Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Canada.
authors: Helvira
authors: H
authors: Melo
authors: Department of Physiology and Pharmacology and Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Canada.
authors: Reem
authors: R
authors: Aboushousha
authors: Department of Physiology and Pharmacology and Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Canada.
authors: Lauren
authors: L
authors: Taylor
authors: Department of Physiology and Pharmacology and Snyder Institute for Chronic Diseases, University of Calgary, Calgary, Canada altier@ucalgary.ca.
authors: Christophe
authors: C
authors: Altier
mesh_terms: D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D000871:Anthelmintics / Q000494:pharmacology; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D002211:Capsaicin / Q000494:pharmacology; D002478:Cells, Cultured; D002586:Cesium / Q000494:pharmacology; D002712:Chlorides / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005620:Freund's Adjuvant / Q000633:toxicity; D005727:Ganglia, Spinal / Q000166:cytology / Q000187:drug effects; D015870:Gene Expression / Q000187:drug effects; D006146:Guanidines / Q000494:pharmacology; D057809:HEK293 Cells; D050883:HSC70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007249:Inflammation / Q000139:chemically induced / Q000188:drug therapy; D051379:Mice; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010146:Pain / Q000209:etiology / Q000378:metabolism / Q000473:pathology; D026902:Potassium Channel Blockers / Q000494:pharmacology; D011807:Quinolizines / Q000494:pharmacology; D051381:Rats; D050916:TRPV Cation Channels / Q000235:genetics / Q000378:metabolism*; D000093842:Matrines
chemical_list: D000470:Alkaloids; D000871:Anthelmintics; D000903:Antibiotics, Antineoplastic; D002712:Chlorides; D004791:Enzyme Inhibitors; D006146:Guanidines; D050883:HSC70 Heat-Shock Proteins; D026902:Potassium Channel Blockers; D011807:Quinolizines; D050916:TRPV Cation Channels; D002586:Cesium; C033797:spergualin; D005620:Freund's Adjuvant; C028019:cesium chloride; D002211:Capsaicin; D000093842:Matrines
keywords: ATPase; cell stress; heat shock cognate 70; rho-associated protein kinase; transient receptor potential vanilloid type 1 channel