Hhex Directly Represses BIM-Dependent Apoptosis to Promote NK Cell Development and Maintenance

Integrative analysis of DNA methylation and gene expression in skin cutaneous melanoma by bioinformatic approaches

Skin cutaneous melanoma represents a significant threat among skin cancers. Investigating key methylated genes with prognostic implications remains an area ripe for exploration in this field. This study aims to identify survival-associated methylated genes and their specific methylation sites in skin cutaneous melanoma through integrated bioinformatic analysis. Utilizing data from the Cancer Genome Atlas database, gene methylation and expression files were analyzed. The results indicate that patients with skin cutaneous melanoma exhibiting high expression of hypomethylated HHEX experience better outcomes compared to those with low expression of hypermethylated HHEX. Furthermore, fifteen methylation sites within HHEX were found to significantly correlate with its expression levels. Expression of HHEX demonstrated a downward trend across pathological stages I-IV. The identified driven gene, HHEX, likely plays a crucial role in the survival of skin cutaneous melanoma patients. These findings provide new epigenetic insights and potential targets for early prognosis prediction in skin cutaneous melanoma.

Dichotomous outcomes of TNFR1 and TNFR2 signaling in NK cell-mediated immune responses during inflammation

Natural killer (NK) cell function is regulated by a balance of activating and inhibitory signals. Tumor necrosis factor (TNF) is an inflammatory cytokine ubiquitous across homeostasis and disease, yet its role in regulation of NK cells remains unclear. Here, we find upregulation of the immune checkpoint protein, T cell immunoglobulin and mucin domain 3 (Tim3), is a biomarker of TNF signaling in NK cells during Salmonella Typhimurium infection. In mice with conditional deficiency of either TNF receptor 1 (TNFR1) or TNF receptor 2 (TNFR2) in NK cells, we find TNFR1 limits bacterial clearance whereas TNFR2 promotes it. Mechanistically, via single cell RNA sequencing we find that both TNFR1 and TNFR2 induce the upregulation of Tim3, while TNFR1 accelerates NK cell death but TNFR2 promotes NK cell accumulation and effector function. Our study thus highlights the complex interplay of TNF-based regulation of NK cells by the two TNF receptors during inflammation.

In utero human cytomegalovirus infection expands NK-like FcγRIII+CD8+ T cells that mediate Fc antibody functions

Human cytomegalovirus (HCMV) profoundly impacts host T and NK cells across the lifespan, yet how this common congenital infection modulates developing fetal immune cell compartments remains underexplored. Using cord blood from neonates with and without congenital HCMV (cCMV) infection, we identify an expansion of Fcγ receptor III-expressing (FcγRIII-expressing) CD8+ T cells following HCMV exposure in utero. Most FcγRIII+CD8+ T cells express the canonical αβ T cell receptor (TCR), but a proportion express noncanonical γδ TCR. FcγRIII+CD8+ T cells are highly differentiated and have increased expression of NK cell markers and cytolytic molecules. Transcriptional analysis reveals FcγRIII+CD8+ T cells upregulate T-bet and downregulate BCL11B, known transcription factors that govern T/NK cell fate. We show that FcγRIII+CD8+ T cells mediate antibody-dependent IFN-γ production and degranulation against IgG-opsonized target cells, similar to NK cell antibody-dependent cellular cytotoxicity (ADCC). FcγRIII+CD8+ T cell Fc effector functions were further enhanced by IL-15, as has been observed in neonatal NK cells. Our study reveals that FcγRIII+CD8+ T cells elicited in utero by HCMV infection can execute Fc-mediated effector functions bridging cellular and humoral immunity and may be a promising target for antibody-based therapeutics and vaccination in early life.

No time to die: Epigenetic regulation of natural killer cell survival

NK cells are short-lived innate lymphocytes that can mediate antigen-independent responses to infection and cancer. However, studies from the past two decades have shown that NK cells can acquire transcriptional and epigenetic modifications during inflammation that result in increased survival and lifespan. These findings blur the lines between the innate and adaptive arms of the immune system, and suggest that the homeostatic mechanisms that govern the persistence of innate immune cells are malleable. Indeed, recent studies have shown that NK cells undergo continuous and strictly regulated adaptations controlling their survival during development, tissue residency, and following inflammation. In this review, we summarize our current understanding of the critical factors regulating NK cell survival throughout their lifespan, with a specific emphasis on the epigenetic modifications that regulate the survival of NK cells in various contexts. A precise understanding of the molecular mechanisms that govern NK cell survival will be important to enhance therapies for cancer and infectious diseases.

IKAROS and AIOLOS directly regulate AP-1 transcriptional complexes and are essential for NK cell development

Ikaros transcription factors are essential for adaptive lymphocyte function, yet their role in innate lymphopoiesis is unknown. Using conditional genetic inactivation, we show that Ikzf1/Ikaros is essential for normal natural killer (NK) cell lymphopoiesis and IKZF1 directly represses Cish, a negative regulator of interleukin-15 receptor resulting in impaired interleukin-15 receptor signaling. Both Bcl2l11 and BIM levels, and intrinsic apoptosis were increased in Ikzf1-null NK cells, which in part accounts for NK lymphopenia as both were restored to normal levels when Ikzf1 and Bcl2l11 were co-deleted. Ikzf1-null NK cells presented extensive transcriptional alterations with reduced AP-1 transcriptional complex expression and increased expression of Ikzf2/Helios and Ikzf3/Aiolos. IKZF1 and IKZF3 directly bound AP-1 family members and deletion of both Ikzf1 and Ikzf3 in NK cells resulted in further reductions in Jun/Fos expression and complete loss of peripheral NK cells. Collectively, we show that Ikaros family members are important regulators of apoptosis, cytokine responsiveness and AP-1 transcriptional activity.

The Haematopoietically-expressed homeobox transcription factor: roles in development, physiology and disease

The Haematopoietically expressed homeobox transcription factor (Hhex) is a transcriptional repressor that is of fundamental importance across species, as evident by its evolutionary conservation spanning fish, amphibians, birds, mice and humans. Indeed, Hhex maintains its vital functions throughout the lifespan of the organism, beginning in the oocyte, through fundamental stages of embryogenesis in the foregut endoderm. The endodermal development driven by Hhex gives rise to endocrine organs such as the pancreas in a process which is likely linked to its role as a risk factor in diabetes and pancreatic disorders. Hhex is also required for the normal development of the bile duct and liver, the latter also importantly being the initial site of haematopoiesis. These haematopoietic origins are governed by Hhex, leading to its crucial later roles in definitive haematopoietic stem cell (HSC) self-renewal, lymphopoiesis and haematological malignancy. Hhex is also necessary for the developing forebrain and thyroid gland, with this reliance on Hhex evident in its role in endocrine disorders later in life including a potential role in Alzheimer's disease. Thus, the roles of Hhex in embryological development throughout evolution appear to be linked to its later roles in a variety of disease processes.

Targeting Myc Interacting Proteins as a Winding Path in Cancer Therapy

MYC, as a well-known oncogene, plays essential roles in promoting tumor occurrence, development, invasion and metastasis in many kinds of solid tumors and hematologic neoplasms. In tumors, the low expression and the short half-life of Myc are reversed, cause tumorigenesis. And proteins that directly interact with different Myc domains have exerted a significant impact in the process of Myc-driven carcinogenesis. Apart from affecting the transcription of Myc target genes, Myc interaction proteins also regulate the stability of Myc through acetylation, methylation, phosphorylation and other post-translational modifications, as well as competitive combination with Myc. In this review, we summarize a series of Myc interacting proteins and recent advances in the related inhibitors, hoping that can provide new opportunities for Myc-driven cancer treatment.

HIF1α is required for NK cell metabolic adaptation during virus infection

Natural killer (NK) cells are essential for early protection against virus infection and must metabolically adapt to the energy demands of activation. Here, we found upregulation of the metabolic adaptor hypoxia-inducible factor-1α (HIF1α) is a feature of mouse NK cells during murine cytomegalovirus (MCMV) infection in vivo. HIF1α-deficient NK cells failed to control viral load, causing increased morbidity. No defects were found in effector functions of HIF1αKO NK cells; however, their numbers were significantly reduced. Loss of HIF1α did not affect NK cell proliferation during in vivo infection and in vitro cytokine stimulation. Instead, we found that HIF1α-deficient NK cells showed increased expression of the pro-apoptotic protein Bim and glucose metabolism was impaired during cytokine stimulation in vitro. Similarly, during MCMV infection HIF1α-deficient NK cells upregulated Bim and had increased caspase activity. Thus, NK cells require HIF1α-dependent metabolic functions to repress Bim expression and sustain cell numbers for an optimal virus response.