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Pim serine/threonine kinases regulate the stability of Socs-1 protein
X Peter Chen1, Julie A Losman, Simone Cowan
1Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA.
Abstract:
Studies of SOCS-1-deficient mice have implicated Socs-1 in the suppression of JAK-STAT (Janus tyrosine kinase-signal transducers and activators of transcription) signaling and T cell development. It has been suggested that the levels of Socs-1 protein may be regulated through the proteasome pathway. Here we show that Socs-1 interacts with members of the Pim family of serine/threonine kinases in thymocytes. Coexpression of the Pim kinases with Socs-1 results in phosphorylation and stabilization of the Socs-1 protein. The protein levels of Socs-1 are significantly reduced in the Pim-1(-/-), Pim-2(-/-) mice as compared with wild-type mice. Similar to Socs-1(-/-) mice, thymocytes from Pim-1(-/-), Pim-2(-/-) mice showed prolonged Stat6 phosphorylation upon IL-4 stimulation. These data suggest that the Pim kinases may regulate cytokine-induced JAK-STAT signaling through modulation of Socs-1 protein levels.
Insights
Pim kinases stabilize the Socs-1 protein, which regulates Janus tyrosine kinase-signal transducers and activators of transcription (JAK-STAT) signaling. Pim kinase deficiency reduces Socs-1 levels, impacting T cell development and cytokine signaling.
Area of Science:
- Immunology
- Molecular Biology
- Cell Signaling
Background:
- Suppressor of Cytokine Signaling 1 (SOCS-1) is crucial for regulating Janus tyrosine kinase-signal transducers and activators of transcription (JAK-STAT) signaling and T cell development.
- The proteasome pathway is hypothesized to regulate SOCS-1 protein levels.
Purpose of the Study:
- To investigate the interaction between SOCS-1 and Pim kinases in thymocytes.
- To determine the role of Pim kinases in regulating SOCS-1 protein stability and JAK-STAT signaling.
Main Methods:
- Coexpression of Pim kinases and SOCS-1 in thymocytes.
- Analysis of SOCS-1 protein levels in wild-type and Pim-1/Pim-2 double knockout mice.
- Assessment of Stat6 phosphorylation upon IL-4 stimulation in thymocytes from knockout mice.
Main Results:
- Pim kinases phosphorylate and stabilize SOCS-1 protein.
- SOCS-1 protein levels are significantly reduced in Pim-1(-/-), Pim-2(-/-) mice.
- Thymocytes from Pim-1(-/-), Pim-2(-/-) mice exhibit prolonged Stat6 phosphorylation, similar to SOCS-1(-/-) mice.
Conclusions:
- Pim kinases modulate SOCS-1 protein levels.
- Pim kinases play a regulatory role in cytokine-induced JAK-STAT signaling via SOCS-1.