title: Desert hedgehog-patched 2 expression in peripheral nerves during Wallerian degeneration and regeneration.
abstract: Hedgehog proteins are important in the development of the nervous system. As Desert hedgehog (Dhh) is involved in the development of peripheral nerves and is expressed in adult nerves, it may play a role in the maintenance of adult nerves and degeneration and regeneration after injury. We firstly investigated the Dhh-receptors, which are expressed in mouse adult nerves. The Dhh receptor patched(ptc)2 was detected in adult sciatic nerves using RT-PCR, however, ptc1 was undetectable under the same experimental condition. Using RT-PCR in purified cultures of mouse Schwann cells and fibroblasts, we found ptc2 mRNA in Schwann cells, and at much lower levels, in fibroblasts. By immunohistochemistry, Ptc2 protein was seen on unmyelinated nerve fibers. Then we induced crush injury to the sciatic nerves of wild-type (WT) and dhh-null mice and the distal stumps of injured nerves were analyzed morphologically at different time points and expression of dhh and related receptors was also measured by RT-PCR in WT mice. In dhh-null mice, degeneration of myelinated fibers was more severe than in WT mice. Furthermore, in regenerated nerves of dhh-null mice, minifascicular formation was even more extensive than in dhh-null intact nerves. Both dhh and ptc2 mRNA levels were down-regulated during the degenerative phase postinjury in WT mice, while levels rose again during the phase of nerve regeneration. These results suggest that the Dhh-Ptc2 signaling pathway may be involved in the maintenance of adult nerves and may be one of the factors that directly or indirectly determines the response of peripheral nerves to injury.
authors.affiliation: Department of Neurology and Geriatrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, Japan.
authors.forename: Sepideh N
authors.initials: SN
authors.lastname: Bajestan
authors.forename: Fujio
authors.initials: F
authors.lastname: Umehara
authors.forename: Yuko
authors.initials: Y
authors.lastname: Shirahama
authors.forename: Kayoko
authors.initials: K
authors.lastname: Itoh
authors.forename: Soheila
authors.initials: S
authors.lastname: Sharghi-Namini
authors.forename: Kristjan R
authors.initials: KR
authors.lastname: Jessen
authors.forename: Rhona
authors.initials: R
authors.lastname: Mirsky
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Osame
mesh_terms: D000818:Animals; D005260:Female; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D051379:Mice; D009409:Nerve Crush; D009416:Nerve Regeneration / Q000502:physiology*; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D000072082:Patched-2 Receptor; D012333:RNA, Messenger / Q000032:analysis; D011956:Receptors, Cell Surface / Q000096:biosynthesis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012584:Sciatic Nerve / Q000378:metabolism*; D014855:Wallerian Degeneration / Q000378:metabolism*
chemical_list: D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D000072082:Patched-2 Receptor; C000606240:Ptch1 protein, mouse; C000606241:Ptch2 protein, mouse; D012333:RNA, Messenger; D011956:Receptors, Cell Surface