title: Different modifications of phosphorylated Smad3C and Smad3L through TGF-β after spinal cord injury in mice.
abstract: Transforming growth factor-β (TGF-β) is an anti-inflammatory cytokine and is expressed in the injured spinal cord. TGF-β signals through receptors to activate Smad proteins, which translocate into the nucleus. In the present study, we investigated the chronological alterations and cellular locations of the TGF-β/Smad signaling pathway following spinal cord injury (SCI) in mice. ELISA analysis showed that the concentration of interleukin-6 (IL-6) in injured spinal cords significantly increases immediately after SCI, while the concentration of TGF-β gradually increased after SCI, peaked at 2 days, and then gradually decreased. Immunohistochemical studies revealed that Smad3 was mainly expressed in neurons of the spinal cord. Phosphorylated Smad3 at the C-terminus (p-Smad3C) was stained within the motor neurons in the anterior horn, while phosphorylated Smad3 at the linker regions (p-Smad3L) was expressed in astrocytes within gray matter. These findings suggest that SCI induces gradual increases in TGF-β and induces different activation of p-Smad3C and p-Smad3L. Phosphorylated Smad3C might be involved in neuronal degeneration after SCI, and p-Smad3L may play a role in glial scar formation by astrocytes.
authors.affiliation: Department of Neurological Surgery, Aichi Medical University, 1-1 Yazakokarimata, Nagakute, Aichi 480-1195, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Joko
authors.forename: Koji
authors.initials: K
authors.lastname: Osuka
authors.forename: Nobuteru
authors.initials: N
authors.lastname: Usuda
authors.forename: Kimie
authors.initials: K
authors.lastname: Atsuzawa
authors.forename: Masahiro
authors.initials: M
authors.lastname: Aoyama
authors.forename: Masakazu
authors.initials: M
authors.lastname: Takayasu
mesh_terms: D000818:Animals; D051379:Mice; D009474:Neurons / Q000378:metabolism*; D010766:Phosphorylation; D015398:Signal Transduction / Q000502:physiology*; D051900:Smad3 Protein / Q000378:metabolism*; D013119:Spinal Cord Injuries / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism*
chemical_list: D051900:Smad3 Protein; D016212:Transforming Growth Factor beta
keywords: Interleukin-6; Phosphorylation; Smad3; Spinal cord injury; TGF-β