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PKC-zeta expression is lower in osteoblasts from arthritic patients: IL1-beta and TNF-alpha induce a similar decrease
Nicoletta Zini1, Alberto Bavelloni, Gina Lisignoli
1IGM-CNR, Sezione di Bologna c/o IOR, via di Barbiano 1/10, 40136 Bologna, Italy.
Journal of Cellular Biochemistry
|June 2, 2007
Summary
Osteoarthritis and rheumatoid arthritis patients show altered Protein Kinase C (PKC) isoform expression in osteoblasts. Proinflammatory cytokines like IL-1beta and TNF-alpha decrease PKC-zeta, mimicking changes seen in arthritis.
Area of Science:
- Biochemistry and Molecular Biology
- Cell Biology
- Immunology
Background:
- Protein Kinase C (PKC) is a crucial enzyme family regulating diverse cellular functions.
- PKC isoforms play significant roles in cell proliferation, differentiation, and signal transduction.
- Dysregulation of PKC signaling is implicated in various pathological conditions, including inflammatory diseases.
Purpose of the Study:
- To investigate the expression patterns of 11 Protein Kinase C (PKC) isoforms in osteoblasts from patients with osteoarthritis (OA) and rheumatoid arthritis (RA).
- To compare PKC isoform expression in arthritic osteoblasts with those from post-traumatic (PT) patients.
- To determine the effect of proinflammatory cytokines on PKC isoform expression in osteoblasts.
Main Methods:
- Western blotting was employed to analyze the expression of nine PKC isoforms in osteoblasts.
- Immuno-electron microscopy was used to confirm subcellular distribution and quantitative differences.
- Osteoblasts were treated with interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) to assess cytokine effects.
Main Results:
- Nine PKC isoforms were detected in osteoblasts: -alpha, -beta(I), -beta(II), -delta, -theta, -epsilon, -zeta, -iota/lambda, and -micro.
- Osteoarthritis and rheumatoid arthritis patients exhibited increased expression of PKC-theta and -micro, alongside decreased expression of PKC-epsilon and -zeta compared to normal cells.
- Treatment with IL-1β and TNF-α significantly reduced PKC-zeta expression in post-traumatic osteoblasts, mirroring findings in arthritic patients.
Conclusions:
- Specific PKC isoforms show altered expression in osteoblasts from patients with osteoarthritis and rheumatoid arthritis.
- Proinflammatory cytokines, such as IL-1β and TNF-α, can modulate PKC-zeta expression in osteoblasts.
- These findings suggest a potential role for PKC signaling dysregulation in the pathogenesis of arthritis.
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