The ATP-Binding Cassette Gene ABCF1 Functions as an E2 Ubiquitin-Conjugating Enzyme Controlling Macrophage Polarization to Dampen Lethal Septic Shock.
Arora Hitesh,Wilcox Sara Morgan,Johnson Laura Alexandra,Munro Lonna,Eyford Brett Alexander,Pfeifer Cheryl Gurine,Welch Ian,Jefferies Wilfred Arthur
Sepsis is a bi-phasic inflammatory disease that threatens approximately 30 million lives and claims over 14 million annually, yet little is known regarding the molecular switches and pathways that regulate this disease. Here, we have described ABCF1, an ATP-Binding Cassette (ABC) family member protein, which possesses an E2 ubiquitin enzyme activity, through which it controls the Lipopolysaccharide (LPS)- Toll-like Receptor-4 (TLR4) mediated gram-negative insult by targeting key proteins for K63-polyubiquitination. Ubiquitination by ABCF1 shifts the inflammatory profile from an early phase MyD88-dependent to a late phase TRIF-dependent signaling pathway, thereby regulating TLR4 endocytosis and modulating macrophage polarization from M1 to M2 phase. Physiologically, ABCF1 regulates the shift from the inflammatory phase of sepsis to the endotoxin tolerance phase, and modulates cytokine storm and interferon-β (IFN-β)-dependent production by the immunotherapeutic mediator, SIRT1. Consequently, ABCF1 controls sepsis induced mortality by repressing hypotension-induced renal circulatory dysfunction.
Modulation of M2 macrophage polarization by the crosstalk between Stat6 and Trim24.
Yu Tao,Gan Shucheng,Zhu Qingchen,Dai Dongfang,Li Ni,Wang Hui,Chen Xiaosong,Hou Dan,Wang Yan,Pan Qiang,Xu Jing,Zhang Xingli,Liu Junli,Pei Siyu,Peng Chao,Wu Ping,Romano Simona,Mao Chaoming,Huang Mingzhu,Zhu Xiaodong,Shen Kunwei,Qin Jun,Xiao Yichuan
Stat6 is known to drive macrophage M2 polarization. However, how macrophage polarization is fine-tuned by Stat6 is poorly understood. Here, we find that Lys383 of Stat6 is acetylated by the acetyltransferase CREB-binding protein (CBP) during macrophage activation to suppress macrophage M2 polarization. Mechanistically, Trim24, a CBP-associated E3 ligase, promotes Stat6 acetylation by catalyzing CBP ubiquitination at Lys119 to facilitate the recruitment of CBP to Stat6. Loss of Trim24 inhibits Stat6 acetylation and thus promotes M2 polarization in both mouse and human macrophages, potentially compromising antitumor immune responses. By contrast, Stat6 mediates the suppression of TRIM24 expression in M2 macrophages to contribute to the induction of an immunosuppressive tumor niche. Taken together, our findings establish Stat6 acetylation as an essential negative regulatory mechanism that curtails macrophage M2 polarization.
Etomoxir Inhibits Macrophage Polarization by Disrupting CoA Homeostasis.
Divakaruni Ajit S,Hsieh Wei Yuan,Minarrieta Lucía,Duong Tin N,Kim Kristen K O,Desousa Brandon R,Andreyev Alexander Y,Bowman Caitlyn E,Caradonna Kacey,Dranka Brian P,Ferrick David A,Liesa Marc,Stiles Linsey,Rogers George W,Braas Daniel,Ciaraldi Theodore P,Wolfgang Michael J,Sparwasser Tim,Berod Luciana,Bensinger Steven J,Murphy Anne N
Long-chain fatty acid (LCFA) oxidation has been shown to play an important role in interleukin-4 (IL-4)-mediated macrophage polarization (M(IL-4)). However, many of these conclusions are based on the inhibition of carnitine palmitoyltransferase-1 with high concentrations of etomoxir that far exceed what is required to inhibit enzyme activity (EC < 3 μM). We employ genetic and pharmacologic models to demonstrate that LCFA oxidation is largely dispensable for IL-4-driven polarization. Unexpectedly, high concentrations of etomoxir retained the ability to disrupt M(IL-4) polarization in the absence of Cpt1a or Cpt2 expression. Although excess etomoxir inhibits the adenine nucleotide translocase, oxidative phosphorylation is surprisingly dispensable for M(IL-4). Instead, the block in polarization was traced to depletion of intracellular free coenzyme A (CoA), likely resulting from conversion of the pro-drug etomoxir into active etomoxiryl CoA. These studies help explain the effect(s) of excess etomoxir on immune cells and reveal an unappreciated role for CoA metabolism in macrophage polarization.
The Nuclear Receptor PPARγ Controls Progressive Macrophage Polarization as a Ligand-Insensitive Epigenomic Ratchet of Transcriptional Memory.
Daniel Bence,Nagy Gergely,Czimmerer Zsolt,Horvath Attila,Hammers David W,Cuaranta-Monroy Ixchelt,Poliska Szilard,Tzerpos Petros,Kolostyak Zsuzsanna,Hays Tristan T,Patsalos Andreas,Houtman René,Sauer Sascha,Francois-Deleuze Jean,Rastinejad Fraydoon,Balint Balint L,Sweeney H Lee,Nagy Laszlo
Macrophages polarize into distinct phenotypes in response to complex environmental cues. We found that the nuclear receptor PPARγ drove robust phenotypic changes in macrophages upon repeated stimulation with interleukin (IL)-4. The functions of PPARγ on macrophage polarization in this setting were independent of ligand binding. Ligand-insensitive PPARγ bound DNA and recruited the coactivator P300 and the architectural protein RAD21. This established a permissive chromatin environment that conferred transcriptional memory by facilitating the binding of the transcriptional regulator STAT6 and RNA polymerase II, leading to robust production of enhancer and mRNAs upon IL-4 re-stimulation. Ligand-insensitive PPARγ binding controlled the expression of an extracellular matrix remodeling-related gene network in macrophages. Expression of these genes increased during muscle regeneration in a mouse model of injury, and this increase coincided with the detection of IL-4 and PPARγ in the affected tissue. Thus, a predominantly ligand-insensitive PPARγ:RXR cistrome regulates progressive and/or reinforcing macrophage polarization.