title: Engineering an endomorphin-2 gene for use in neuropathic pain therapy.
abstract: Endomorphin-2 (EM-2) is a carboxy-amidated tetrapeptide that binds the mu-opioid receptor with high affinity and is analgesic in several animal models of pain. Endomorphin peptides have been isolated from bovine and human brain, but no DNA sequences corresponding to a potential preproendomorphin gene have been identified in human genome sequence databases. In this study we designed a tripartite synthetic gene to direct production, cleavage, and amidation of EM-2, and placed the endomorphin gene expression cassette in a replication defective Herpes simplex virus (HSV) vector (vEM2). Biosynthesis of amidated endomorphin-2 peptide was quantified by radioimmunoassay and the identity confirmed by mass spectroscopy following vEM2 transduction of cultured primary dorsal root ganglion neurons. Subcutaneous inoculation of vEM2 resulted in vector delivery to dorsal root ganglion where expression of EM-2 peptide from the engineered gene was confirmed by ELISA. vEM2 delivery provided an analgesic effect in the spinal nerve ligation model of neuropathic pain measured by reduction of mechanical allodynia and thermal hyperalgesia. The analgesic effect of vEM2 was blocked by intrathecal delivery of the mu-receptor antagonist CTOP. The gene construct design described represents a broadly useful platform for biosynthesis and delivery of carboxy-amidated peptides for therapeutic and experimental purposes, and the results demonstrate that HSV-gene transfer to sensory neurons provides an effective means to achieve local biosynthesis of endomorphin peptides for the treatment of chronic pain.
authors: Department of Molecular Genetics and Biochemistry, University of Pittsburgh School of Medicine, E1240 Biomedical Science Tower, 200 Lothrop Street, Pittsburgh, PA 15261, USA.
authors: Darren
authors: D
authors: Wolfe
authors: Shuanglin
authors: S
authors: Hao
authors: Jian
authors: J
authors: Hu
authors: Rahul
authors: R
authors: Srinivasan
authors: James
authors: J
authors: Goss
authors: Marina
authors: M
authors: Mata
authors: David J
authors: DJ
authors: Fink
authors: Joseph C
authors: JC
authors: Glorioso
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005727:Ganglia, Spinal / Q000187:drug effects; D018014:Gene Transfer Techniques; D005818:Genetic Engineering / Q000379:methods*; D005822:Genetic Vectors / Q000502:physiology; D006930:Hyperalgesia / Q000188:drug therapy; D008026:Ligation / Q000379:methods; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D009437:Neuralgia / Q000209:etiology / Q000628:therapy*; D009842:Oligopeptides / Q000096:biosynthesis* / Q000627:therapeutic use*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D013127:Spinal Nerves / Q000473:pathology
chemical_list: D009842:Oligopeptides; C105294:endomorphin 2