Enhancers not only activate target promoters to stimulate messenger RNA (mRNA) synthesis, but they themselves also undergo transcription to produce enhancer RNAs (eRNAs), the significance of which is not well understood. Transcription at the participating enhancer-promoter pair appears coordinated, but it is unclear why and how. Here, we employ cell-free transcription assays using constructs derived from the human GREB1 locus to demonstrate that transcription at an enhancer and its target promoter is interdependent. This interdependence is observable under conditions where direct enhancer-promoter contact (EPC) takes place. We demonstrate that transcription activation at a participating enhancer-promoter pair is dependent on i) the mutual availability of the enhancer and promoter, ii) the state of transcription at both the enhancer and promoter, iii) local abundance of both eRNA and mRNA, and iv) direct EPC. Our results suggest transcriptional interdependence between the enhancer and the promoter as the basis of their transcriptional concurrence and coordination throughout the genome. We propose a model where transcriptional concurrence, coordination and interdependence are possible if the participating enhancer and promoter are entangled in the form of EPC, reside in a proteinaceous bubble, and utilize shared transcriptional resources and regulatory inputs.

Steroid receptor coactivator 3 (SRC-3) is most strongly expressed in regulatory T cells (Tregs) and B cells, suggesting that it plays an important role in the regulation of Treg function. Using an aggressive E0771 mouse breast cell line syngeneic immune-intact murine model, we observed that breast tumors were "permanently eradicated" in a genetically engineered tamoxifen-inducible Treg-cell-specific SRC-3 knockout (KO) female mouse that does not possess a systemic autoimmune pathological phenotype. A similar eradication of tumor was noted in a syngeneic model of prostate cancer. A subsequent injection of additional E0771 cancer cells into these mice showed continued resistance to tumor development without the need for tamoxifen induction to produce additional SRC-3 KO Tregs. SRC-3 KO Tregs were highly proliferative and preferentially infiltrated into breast tumors by activating the chemokine (C-C motif) ligand (Ccl) 19/Ccl21/chemokine (C-C motif) receptor (Ccr)7 signaling axis, generating antitumor immunity by enhancing the interferon-γ/C-X-C motif chemokine ligand (Cxcl) 9 signaling axis to facilitate the entrance and function of effector T cells and natural killer cells. SRC-3 KO Tregs also show a dominant effect by blocking the immune suppressive function of WT Tregs. Importantly, a single adoptive transfer of SRC-3 KO Tregs into wild-type E0771 tumor-bearing mice can completely abolish preestablished breast tumors by generating potent antitumor immunity with a durable effect that prevents tumor reoccurrence. Therefore, treatment with SRC-3-deleted Tregs represents an approach to completely block tumor growth and recurrence without the autoimmune side effects that typically accompany immune checkpoint modulators.

Progressive remodeling of the heart, resulting in cardiomyocyte (CM) loss and increased inflammation, fibrosis, and a progressive decrease in cardiac function, are hallmarks of myocardial infarction (MI)-induced heart failure. We show that MCB-613, a potent small molecule stimulator of steroid receptor coactivators (SRCs) attenuates pathological remodeling post-MI. MCB-613 decreases infarct size, apoptosis, hypertrophy, and fibrosis while maintaining significant cardiac function. MCB-613, when given within hours post MI, induces lasting protection from adverse remodeling concomitant with: 1) inhibition of macrophage inflammatory signaling and interleukin 1 (IL-1) signaling, which attenuates the acute inflammatory response, 2) attenuation of fibroblast differentiation, and 3) promotion of Tsc22d3-expressing macrophages-all of which may limit inflammatory damage. SRC stimulation with MCB-613 (and derivatives) is a potential therapeutic approach for inhibiting cardiac dysfunction after MI.