HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

Published online before print September 7, 2007

This Article Full Text (Reprint (PDF)) Supplemental Table All Versions of this Article: jlb.0707447v1 82/6/1564    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Weigelt, K. Articles by Langmann, T. Search for Related Content PubMed PubMed Citation Articles by Weigelt, K. Articles by Langmann, T.

© by The Society for Leukocyte Biology
Journal of Leukocyte Biology, doi:10.1189/jlb.0707447

Received for publication July 5, 2007.
Revised August 9, 2007.
Accepted for publication August 15, 2007.

Article

Dap12 expression in activated microglia from retinoschisin-deficient retina and its PU.1-dependent promoter regulation

Karin Weigelt ^*, Wolfgang Ernst ^*, Yana Walczak ^*, Stefanie Ebert ^*, Thomas Loenhardt ^*, Maja Klug , Michael Rehli , Bernhard H. F. Weber ^*, and Thomas Langmann ^*@

*Institute of Human Genetics, University of Regensburg, and Department of Hematology and Oncology, University Hospital Regensburg, Germany

^@ To whom correspondence should be addressed. E-mail: thomas.langmann{at}klinik.uni-regensburg.de.

	Abstract

Several alterations in the expression of immune-related transcripts were identified recently in the degenerating retina of the retinoschisin knockout (Rs1h^–/Y) mouse, including the strong expression of the adaptor protein Dap12. As Dap12 is found in leukocytes, we hypothesized that its disease-related expression may be confined to activated retinal microglia cells. To test this hypothesis, we established a procedure for isolation and culture of retinal microglia cells and performed genome-wide expression profiling from Rs1h^–/Y and control microglia. While retaining their activated state in culture, ex vivo microglia expressed high levels of Dap12 and the transcription factor PU.1. The activation-dependent induction of Dap12 was also confirmed in the microglia cell line BV-2 following in vitro stimulation. To examine the transcriptional regulation of Dap12 further, macrophage cell lines were transfected with several Dap12 reporter constructs. Promoter deletion assays and site-directed mutagenesis experiments demonstrated an essential role of evolutionarily conserved PU.1 consensus sites in the proximal –104/+118 Dap12 promoter. In vitro and in vivo binding of PU.1 to this promoter region was demonstrated using EMSA and chromatin immunoprecipitation. Knockdown of PU.1 by RNA interference caused a significant reduction of endogenous Dap12 expression and re-expression, and activation of PU.1 in PU.1^-/- progenitor cells induced Dap12 transcription. Taken together, our results indicate that activated microglia from degenerating retinae express high levels of Dap12 and PU.1, and PU.1 controls the myeloid-specific regulation of Dap12 directly and may also play a general role in microglia gene expression during retinal degeneration.

Key Words: Tyrobp • retinal degeneration • myeloid promoter

This article has been cited by other articles:

				S. Ebert, T. Schoeberl, Y. Walczak, K. Stoecker, T. Stempfl, C. Moehle, B. H. F. Weber, and T. Langmann Chondroitin sulfate disaccharide stimulates microglia to adopt a novel regulatory phenotype J. Leukoc. Biol., September 1, 2008; 84(3): 736 - 740. [Abstract] [Full Text] [PDF]