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Updated: May 10, 2026
Automated Impactor for Contusive Spinal Cord Injury Model in Mice
Published on: January 19, 2024
Different modifications of phosphorylated Smad3C and Smad3L through TGF-β after spinal cord injury in mice
Masahiro Joko1, Koji Osuka, Nobuteru Usuda
1Department of Neurological Surgery, Aichi Medical University, 1-1 Yazakokarimata, Nagakute, Aichi 480-1195, Japan.
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.
Insights
Spinal cord injury (SCI) alters transforming growth factor-β (TGF-β) levels and Smad3 activation. Different Smad3 forms in neurons and astrocytes suggest roles in degeneration and glial scarring after SCI.
Area of Science:
- Neuroscience
- Cell Biology
- Biochemistry
Background:
- Transforming growth factor-β (TGF-β) is an anti-inflammatory cytokine.
- TGF-β signaling involves Smad proteins, which translocate to the nucleus.
- The role of TGF-β/Smad pathway in spinal cord injury (SCI) is not fully understood.
Purpose of the Study:
- To investigate the chronological changes and cellular localization of the TGF-β/Smad signaling pathway after SCI in mice.
- To understand the specific roles of different Smad3 phosphorylation sites in SCI.
Main Methods:
- Enzyme-linked immunosorbent assay (ELISA) to measure cytokine concentrations.
- Immunohistochemistry to determine cellular localization and expression of Smad3 and its phosphorylated forms.
Main Results:
- Interleukin-6 (IL-6) increased immediately post-SCI; TGF-β levels rose gradually, peaking at 2 days.
- Smad3 was primarily found in spinal cord neurons.
- Phosphorylated Smad3 at the C-terminus (p-Smad3C) localized to motor neurons, while phosphorylated Smad3 at linker regions (p-Smad3L) was in astrocytes.
Conclusions:
- SCI induces dynamic changes in TGF-β levels and differential activation of Smad3 isoforms.
- p-Smad3C may contribute to neuronal degeneration following SCI.
- p-Smad3L in astrocytes suggests a role in glial scar formation after SCI.
