Tissues in multicellular organisms are serviced by resident macrophages, which perform both generic and tissue-specific functions. The latter relies on unique tissue-specific molecular programs induced by signals from the microenvironment and executed through a combinatorial action of tissue-specific and broadly expressed transcriptional regulators. Here, we identify the transcription factors Bhlhe40 and Bhlhe41 as novel regulators of alveolar macrophages (AMs)  a population that provides the first line of immune defense and executes homeostatic functions in lung alveoli. In the absence of these factors, AMs exhibited decreased proliferation that resulted in a severe disadvantage of knockout AMs in a competitive setting. Gene expression analyses revealed a broad cell-intrinsic footprint of Bhlhe40/Bhlhe41-deficiency manifested by a downregulation of AM signature genes and induction of signature genes of other macrophage lineages. Genome-wide characterization of Bhlhe40 DNA binding suggested that these transcription factors directly repress the expression of lineage-inappropriate genes in AMs. Taken together, these results identify Bhlhe40 and Bhlhe41 as key regulators of AM self-renewal and guardians of their identity. SOURCE: Taras Kreslavsky (taras.kreslavskiy@ki.se) - Taras Kreslavsky Karolinska Institutet

Pluto Bioinformatics

GSE135018: Bhlhe40 and Bhlhe41 transcription factors regulate alveolar macrophage self-renewal and identity