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Interleukin-4 mediates STAT6 activation in 3T3-L1 preadipocytes but not adipocytes
1Department of Nutrition, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
Abstract:
STAT6 is abundantly expressed in 3T3-L1 preadipocytes and adipocytes but activating ligands are not well defined. In this report, we provide evidence that interleukin 4 (IL-4) induced JAK2-mediated STAT6 tyrosine phosphorylation and DNA binding in 3T3-L1 preadipocytes but not in 3T3-L1 adipocytes. Loss of IL-4-mediated STAT6 tyrosine phosphorylation occurred 2 days after preadipocytes were induced to differentiate into adipocytes but when cells remained phenotypically preadipocytes. 3T3-L1 adipocytes were still responsive to IL-4 through tyrosine phosphorylation of other cellular proteins. We conclude that IL-4 signals through STAT6 in 3T3-L1 preadipocytes but not in 3T3-L1 adipocytes. This differentiation-dependent loss of STAT6 activation may be critical for distinct biological effects of IL-4 in 3T3-L1 preadipocytes and adipocytes.
Insights
Interleukin 4 (IL-4) activates STAT6 signaling in preadipocytes but not adipocytes. This loss of STAT6 activation during differentiation may influence IL-4
Area of Science:
- Cellular and Molecular Biology
- Signal Transduction
- Adipogenesis
Background:
- Signal transducer and activator of transcription 6 (STAT6) is highly expressed in 3T3-L1 preadipocytes and adipocytes.
- The specific activating ligands for STAT6 in these cell types are not fully understood.
- Interleukin 4 (IL-4) is a cytokine known to activate STAT6 in various cell types.
Purpose of the Study:
- To investigate the role of IL-4 as an activating ligand for STAT6 in 3T3-L1 preadipocytes and adipocytes.
- To determine if STAT6 activation by IL-4 is affected by the differentiation process of 3T3-L1 cells.
Main Methods:
- Utilized 3T3-L1 preadipocytes and differentiated adipocytes.
- Stimulated cells with IL-4 and assessed STAT6 tyrosine phosphorylation and DNA binding activity.
- Monitored STAT6 activation at different time points during adipocyte differentiation.
- Examined tyrosine phosphorylation of other cellular proteins in response to IL-4 in adipocytes.
Main Results:
- IL-4 induced JAK2-mediated STAT6 tyrosine phosphorylation and DNA binding in 3T3-L1 preadipocytes.
- STAT6 activation by IL-4 was significantly reduced in 3T3-L1 adipocytes, occurring 2 days post-induction of differentiation.
- 3T3-L1 adipocytes retained responsiveness to IL-4, evidenced by the tyrosine phosphorylation of other cellular proteins.
Conclusions:
- IL-4 signals through STAT6 in 3T3-L1 preadipocytes but not in differentiated 3T3-L1 adipocytes.
- The loss of IL-4-mediated STAT6 activation is dependent on the differentiation status of the cells.
- This differentiation-dependent regulation of STAT6 signaling may be crucial for mediating distinct biological effects of IL-4 in preadipocytes versus adipocytes.