Background: An understanding of the role of Nr4a2 in inflammation is needed. Results: Nr4a2 is a transcription factor that induces expression of M2 characteristic genes, and adoptive transfer of macrophages overexpressing Nr4a2 gives protection against septic mortality. Conclusion: Our data impart a new role for Nr4a2 in skewing macrophage plasticity to M2 type. Significance: Therapeutic intervention of Nr4a2 may provide a cure for inflammatory diseases.

Background: Transcriptional modulation of IL10, a cytokine that blocks phagolysosome maturation, is not well understood. Results: This study demonstrates human IL10 gene repression by direct binding of Rev-erb␣ on Rev-DR2 in the proximal promoter. Conclusion: Rev-erb␣ binds to IL10 proximal promoter, represses expression, and impedes Mycobacterium tuberculosis in human macrophages. Significance: This study provides rationale to target Rev-erb␣ as a therapeutic intervention that might support host defense in tuberculosis.Nuclear receptors modulate macrophage effector functions, which are imperative for clearance or survival of mycobacterial infection. The adopted orphan nuclear receptor Rev-erb␣ is a constitutive transcriptional repressor as it lacks AF2 domain and was earlier shown to be present in macrophages. In the present study, we highlight the differences in the relative subcellular localization of Rev-erb␣ in monocytes and macrophages. The nuclear localization of Rev-erb␣ in macrophages is subsequent to monocyte differentiation. Expression analysis of Rev-erb␣ elucidated it to be considerably more expressed in M1 phenotype in comparison with M2. Rev-erb␣ overexpression augments antimycobacterial properties of macrophage by keeping IL10 in a basal repressed state. Further, promoter analysis revealed that IL10 promoter harbors a Rev-erb␣ binding site exclusive to humans and higher order primates and not mouse, demonstrating a species barrier in its functionality. This direct gene repression is mediated by recruitment of co-repressors NCoR and HDAC3. In addition, our data elucidate that its overexpression reduced the survival of intracellular pathogen Mycobacterium tuberculosis by enhancing phagosome lysosome maturation, an event resulting from IL10 repression. Thus, these findings suggest that Rev-erb␣ bestows protection against mycobacterial infection by direct gene repression of IL10 and thus provide a novel target in modulating macrophage microbicidal properties.Macrophages are immune system sentinels with a major role to play in both innate and adaptive immunity. They are the key effectors in antimicrobial defense, atherogenesis, autoimmunity, and many other inflammatory diseases (1). Although the activation, function, classification, and plasticity of these cells have been studied extensively with regard to cellular signaling, the cytokine environment, and surface, cellular, or secretory markers, studies of the underlying molecular mechanism have mostly addressed NF-B (2). Similarly, modulation of macrophage function and alteration of disease pathology by small molecules such as heme, lipids, or drugs such as rifampicin are well understood at the translational level of the effectors (3, 4), but the transcriptional mechanism involving interactions of these ligands with transcriptional molecules and the resulting expression patterns have not been investigated.This study focuses on Rev-erb␣, an adopted orphan nuclear receptor that belongs to the steroid/thyroid hormone receptor superfamily and is a known ...

Abbreviations: 3-MA, 3-methyladenine; AO, acridine orange; ARNTL/BMAL1, aryl hydrocarbon receptor nuclear translocator-like; AVOs, acidic vesicular organelles; CFU, colony forming unit; LAMP1, lysosomal-associated membrane protein 1; MAP1LC3/LC3, microtubule-associated protein 1 light chain 3; MDC, monodansylcadaverine; PFA, paraformaldehyde; PIK3C3/VPS34, phosphatidylinositol 3-kinase, catalytic subunit type 3; PMA, phorbol 12-myristate 13-acetate; SD, standard deviation; TFEB, transcription factor EB; ULK1, unc-51 like autophagy activating kinase 1; V-ATPase, vacuolar-type H C ATPase; VPS11, vacuolar protein sorting 11 homolog (S. cerevisiae).NR1D1 (nuclear receptor subfamily 1, group D, member 1), an adopted orphan nuclear receptor, is widely known to orchestrate the expression of genes involved in various biological processes such as adipogenesis, skeletal muscle differentiation, and lipid and glucose metabolism. Emerging evidence suggests that various members of the nuclear receptor superfamily perform a decisive role in the modulation of autophagy. Recently, NR1D1 has been implicated in augmenting the antimycobacterial properties of macrophages and providing protection against Mycobacterium tuberculosis infection by downregulating the expression of the IL10 gene in human macrophages. This antiinfective property of NR1D1 suggests the need for an improved understanding of its role in other host-associated antimycobacterial pathways. The results presented here demonstrate that in human macrophages either ectopic expression of NR1D1 or treatment with its agonist, GSK4112, enhanced the number of acidic vacuoles as well as the level of MAP1LC3-II, a signature molecule for determination of autophagy progression, in a concentration-and timedependent manner. Conversely, a decrease in NR1D1 in knockdown cells resulted in the reduced expression of lysosomal-associated membrane protein 1, LAMP1, commensurate with a decrease in the level of transcription factor EB, TFEB. This is indicative of that NR1D1 may have a regulatory role in lysosome biogenesis. NR1D1 being a repressor, its positive regulation on LAMP1 and TFEB is suggestive of an indirect byzantine mechanism of action. Its role in the modulation of autophagy and lysosome biogenesis together with its ability to repress IL10 gene expression supports the theory that NR1D1 has a pivotal antimycobacterial function in human macrophages.