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PU.1 regulates cathepsin S expression in professional APCs
Ying Wang1, Rebecca M Baron, Guangli Zhu
1Division of Pulmonary and Critical Care Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA.
Journal of Immunology (Baltimore, Md. : 1950)
|December 21, 2005
Summary
The transcription factor PU.1 directly regulates Cathepsin S (CTSS) gene expression in antigen-presenting cells (APCs). This finding suggests PU.1 influences the cellular processing environment within APCs.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- Cathepsin S (CTSS) is a cysteine protease crucial for antigen presentation in antigen-presenting cells (APCs).
- The Ets family transcription factor PU.1 is highly expressed in myeloid and lymphoid cells, including APCs.
Purpose of the Study:
- To investigate the role of PU.1 in the transcriptional regulation of CTSS in APCs.
- To determine if PU.1 directly binds to and modulates the CTSS promoter.
Main Methods:
- Reporter gene assays in A549 and RAW cells to assess CTSS promoter activity.
- Dominant-negative PU.1 and siRNA knockdown experiments in RAW cells.
- Electrophoretic mobility shift assays (EMSAs) to detect PU.1 binding to the CTSS promoter.
- Chromatin immunoprecipitation (ChIP) to confirm in vivo binding of PU.1 to the CTSS promoter.
Main Results:
- PU.1 significantly enhanced CTSS promoter activity in A549 cells.
- PU.1 knockdown attenuated basal CTSS promoter activity, mRNA, and protein levels in RAW cells.
- EMSAs and ChIP confirmed PU.1 binding to specific Ets consensus sites within the CTSS promoter.
- PU.1, with IFN regulatory factors, further boosted CTSS promoter activity.
Conclusions:
- PU.1 is a key regulator of CTSS transcription in APCs.
- PU.1 directly binds to the CTSS promoter and influences its activity.
- Modulating PU.1 expression could alter the proteolytic environment in APCs, impacting immune responses.