Long noncoding RNAs (lncRNAs) are increasingly being appreciated as participants in regulation of important cellular processes, including transcription. Because lncRNAs are highly cell type specific, they have the potential to contribute to the unique transcriptional repertoire of diverse cells, but underlying mechanisms are unclear. We studied , an erythroid lncRNA encoded downstream ofγ-globin (). and γ-globin genes are dynamically cotranscribed in erythroid cells in vivo. Deletion of using CRISPR/Cas9 editing shows that it specifically contributes to regulation of γ-globin genes. We used reduction or overexpression of the RNA and inhibition of transcription through the locus by CRISPRi to distinguish functions of the transcript vs the underlying sequence. Transcription of the locus is critical for looping between the γ-globin genes and sequences. In contrast, the transcript is dispensable for γ-globin/ looping but interacts with the mediator complex on chromatin. Manipulation of the locus does not compromise γ-globin gene long-range looping interactions with the β-globin locus control region (LCR). These data reveal that regulates γ-globin transcription in a developmental stage-specific fashion together with the LCR by serving as a separate means to increase RNA Pol II density at the γ-globin promoters.

T lymphocytes from patients with acute EBV-induced infectious mononucleosis rapidly die by apoptosis in vitro. Because human and viral IL-10 are likely to be induced during acute EBV infection and display a variety of functions on human T cells, we examined IL-10 effects on infectious mononucleosis T cell death. After 12 h of incubation in medium alone, only 35.6 (+8.2%) of the originally seeded infectious mononucleosis T cells were viable. Addition of human IL-10 (100 U/ml) to T cell cultures significantly improved recovery of viable cells (71.3+6.2%, P = 0.0156). Viral IL-10 had comparable effects to human IL-10 in this system. Protection from death by human and viral IL-10 (100 U/ml) was dose dependent and continued over a 6-d culture period. The human IL-10 effect was neutralized by the anti-human IL-10 mAb 19F1. Morphology and analysis of DNA after separation on agarose gels showed that IL-10 inhibits loss of cell volume, chromatin condensation, and DNA fragmentation, characteristics of death by apoptosis. As assessed by [3Hjthymidine incorporation, the T cells were not induced to proliferate by IL-10 above the level exhibited when first removed from blood. T cells protected from death by IL-10 proliferated to IL-2 and spontaneously killed sensitive targets as effectively as medium-precultured T cells. Thus, IL-10 promotes the survival of infectious mononucleosis T cells otherwise destined to die by apoptosis and may be critical for the establishment of immunologic memory after resolution of the illness. (J. Clin. Invest. 1994. 94:251-260.)

Staphylococcus aureus is the leading cause of skin and skin structure infections (SSSI). The high frequency of recurring SSSI due to S. aureus, including methicillin-resistant S. aureus (MRSA) strains, despite high titers of specific antibodies and circulating T cells, implies that traditional adaptive immunity imparts incomplete protection. We hypothesized that innate immune memory contributes to the protective host defense against recurring MRSA infection. To test this hypothesis, SSSI was induced in wild-type and rag1 Ϫ/Ϫ mice in the BALB/c and C57BL/6 backgrounds. Prior infection (priming) of wild-type and rag1 Ϫ/Ϫ mice of either background afforded protection against repeat infection, as evidenced by reduced abscess severities and decreased CFU densities compared to those in naive controls. Interestingly, protection was greater on the previously infected flank than on the naive flank for wild-type and rag1 Ϫ/Ϫ mice. For wild-type mice, protective efficacy corresponded to increased infiltration of neutrophils (polymorphonuclear leukocytes [PMN]), macrophages (M⌽), Langerin ϩ dendritic cells (LDC), and natural killer (NK) cells. Protection was associated with the induction of interleukin-17A (IL-17A), IL-22, and gamma interferon (IFN-␥) as well as the antimicrobial peptides CRAMP and m␤D-3. Priming also protected rag1 Ϫ/Ϫ mice against recurring SSSI, with increased M⌽ and LDC infiltration and induction of IL-22, CRAMP, and m␤D-3. These findings suggest that innate immune memory, mediated by specific cellular and molecular programs, likely contributes to the localized host defense in recurrent MRSA SSSI. These insights support the development of targeted immunotherapeutic strategies to address the challenge of MRSA infection.