Cooperative Activity of GABP with PU.1 or C/EBPε Regulates Lamin B Receptor Gene Expression, Implicating Their Roles in Granulocyte Nuclear Maturation

The synergistic effect of c-Myb hyperactivation and Pu.1 deficiency induces Pelger-Huët anomaly and promotes sAML

Approximately 30% of patients with myelodysplastic syndrome (MDS) progress to secondary acute myeloid leukemia (sAML) via accumulating gene mutations. Genomic analyses reveal a complex interplay among mutant genes, with co-occurring and mutually exclusive patterns. Hyperactivation of c-MYB and deficiency of PU.1 have been linked to myeloid disorders. We report a case of AML with concurrent PU.1 and c-MYB mutations, exhibiting early onset, high blast count, chemo-resistance, indicating high-risk features, along with elevated Pelger-Huët anomaly (PHA). However, the synergistic mechanism of c-MYB and PU.1 in sAML remains unclear. Using c-Myb-hyperactivation and Pu.1-deficient double-strain (c-mybhyper;pu.1G242D/G242D) zebrafish, we investigated MDS/sAML progression. Surprisingly, the double mutant exhibited a distinct type of neutrophil resembling clinical PHA cells and demonstrated a higher rate of MDS/sAML transformation. Further expression analysis revealed reduced lmnb1 expression in double-mutant zebrafish. Knockdown of lmnb1 resulted in PHA and increased blast cells, while overexpression of lmnb1 in c-mybhyper;pu.1G242D/G242D reduced PHA cell level. This suggests that c-Myb hyperactivation and Pu.1 deficiency synergistically reduce lmnb1 expression, inducing the development of PHA-like neutrophils and promoting MDS/sAML progression in zebrafish. Moreover, coadministration of cell cycle inhibitor cytarabine (Ara-C) and the differential inducer all-trans retinoic acid (ATRA) could effectively relieve the neutrophil expansion and PHA symptoms in c-mybhyper;pu.1G242D/G242D zebrafish. Our findings revealed that c-Myb hyperactivation and Pu.1 deficiency played a synergistic role in sAML development and suggests a phenotypic association between the emergence of PH-like cells and the transformation to sAML. Furthermore, c-mybhyper;pu.1G242D/G242D zebrafish might serve as a suitable sAML model for drug screening.

GABP Promotes Mesangial Cell Proliferation and Renal Fibrosis Through GLI1 in Diabetic Nephropathy

Abnormal proliferation of mesangial cells is a hallmark of diabetic nephropathy (DN). However, the cellular signaling mechanisms that regulate this proliferation remain poorly understood. In this study, it is demonstrated that GA-binding protein (GABP), a member of the ETS family of transcription factors composed of GABPα and GABPβ, plays a significant role in the development of renal fibrosis by modulating mesangial cell proliferation. Notably, the deficiency of GABP in mesangial cells inhibits hyperglycemia-induced proliferation and mitigates renal fibrosis in a murine model of type 2 diabetes mellitus (T2DM). RNA sequencing analysis identifies GLI Family Zinc Finger 1 (GLI1) as the principal downstream effector of GABP in diabetic mice, serving as a crucial regulator of the G1/S transition within the cell cycle. Subsequent investigations have demonstrated that GABP interacts with the GLI1 promoter, facilitating mesangial cell proliferation via GLI1-dependent pathways. This is evidenced by the fact that GLI1 knockdown abrogates the proliferation of mesangial cells with GABP overexpression. Consequently, GABP emerges as a pivotal regulator of renal fibrosis and represents a promising therapeutic target for the treatment of diabetic nephropathy.

ETS Transcription Factors in Immune Cells and Immune-Related Diseases

The development, differentiation, and function of immune cells are precisely regulated by transcription factors. The E26 transformation-specific (ETS) transcription factor family is involved in various physiological and pathological processes by regulating cell proliferation, differentiation, and apoptosis. Emerging evidence has suggested that ETS family proteins are intimately involved in the development and function of immune cells. This review summarizes the role of the ETS family in immune cells and immune-related disorders. Seven transcription factors within the ETS family, including PU.1, ETV5, ETV6, ETS1/2, ELK3, and ELF1, play essential roles in the development and function of T cells, B cells, macrophages, neutrophils, and dendritic cells. Furthermore, they are involved in the occurrence and development of immune-related diseases, including tumors, allergies, autoimmune diseases, and arteriosclerosis. This review is conducive to a comprehensive overview of the role of the ETS family in immune cells, and thus is informative for the development of novel therapeutic strategies targeting the ETS family for immune-related diseases.

Circadian disturbances by altering the light-dark cycle negatively affects hematopoietic function of bone marrow in mice

Circadian rhythms in metabolically active tissues are crucial for maintaining physical health. Circadian disturbance (CD) can cause various health issues, such as metabolic abnormalities and immune and cognitive dysfunctions. However, studies on the role of CD in immune cell development and differentiation, as well as the rhythmic expression of the core clock genes and their altered expression under CD, remain unclear. Therefore, we exposed C57bl/6j mice to repeated reversed light-dark cycles for 90 days to research the effects of CD on bone marrow (BM) hematopoietic function. We also researched the effects of CD on endogenous circadian rhythms, temporally dependent expression in peripheral blood and myeloid leukocytes, environmental homeostasis within BM, and circadian oscillations of hematopoietic-extrinsic cues. Our results confirmed that when the light and dark cycles around mice were frequently reversed, the circadian rhythmic expression of the two main circadian rhythm markers, the hypothalamic clock gene, and serum melatonin, was disturbed, indicating that the body was in a state of endogenous CD. Furthermore, CD altered the temporally dependent expression of peripheral blood and BM leukocytes and destroyed environmental homeostasis within the BM as well as circadian oscillations of hematopoietic-extrinsic cues, which may negatively affect BM hematopoiesis in mice. Collectively, these results demonstrate that circadian rhythms are vital for maintaining health and suggest that the association between CD and hematopoietic dysfunction warrants further investigation.

The circadian neutrophil, inside-out

The circadian clock has sway on a myriad of physiological targets, among which the immune and inflammatory systems are particularly prominent. In this review, we discuss how neutrophils, the wildcard of the immune system, are regulated by circadian oscillations. We describe cell-intrinsic and extrinsic diurnal mechanisms governing the general physiology and function of these cells, from purely immune to homeostatic. Repurposing the concepts discovered in other cell types, we then speculate on various uncharted avenues of neutrophil-circadian relationships, such as topology, metabolism, and the regulation of tissue clocks, with the hope of identifying exciting new avenues of work in the context of circadian immunity.

Aged neutrophils form mitochondria-dependent vital NETs to promote breast cancer lung metastasis

Background

Neutrophils-linked premetastatic niche plays a key role in tumor metastasis, but not much is known about the heterogeneity and diverse role of neutrophils in niche formation. Our study focuses on the existence and biological function of a rarely delved subset of neutrophils, named as tumor-associated aged neutrophils (Naged, CXCR4⁺CD62L^low), involved in premetastatic niche formation during breast cancer metastasis.

Methods

We explored the distributions of Naged in 206 patients and mice models (4T1 and MMTV-PyMT) by flow cytometry. The ability of Naged to form neutrophil extracellular traps (NETs) and promote tumor metastasis in patients and mice was determined by polychromatic immunohistochemistry, scanning electron microscopy and real-time video detection. Furthermore, the differences among tumor-associated Naged, Non-Naged and inflammation-associated aged neutrophils were compared by transcriptome, the biological characteristics of Naged were comprehensively analyzed from the perspectives of morphology, the metabolic capacity and mitochondrial function were investigated by Seahorse, co-immunoprecipitation (Co-IP), chromatin immunoprecipitation (ChIP) and transmission electron microscopy (TEM). Finally, 120 patients’ sample were applied to confirm the acceleration of Naged formation through secreted NAMPT, and the importance of blocking this pathway in mice was evaluated.

Results

We find that Naged accumulate in the lung premetastatic niche at early stage of breast tumorigenesis in multiple mice models and also exist in peripheral blood and metastatic lung of patients with breast cancer. Naged exhibit distinct cell marker and morphological feature of oversegmented nuclei. Further transcriptome reveals that Naged are completely different from those of Non-Aged or inflammation-associated aged neutrophils and illustrates that the key transcription factor SIRT1 in Naged is the core to maintain their lifespan via mitophagy for their function. The responsible mechanism is that SIRT1 can induce the opening of mitochondrial permeability transition pore channels to release mitochondrial DNA and lead to the mitochondria-dependent vital NETs formation, rather than traditional Cit-Histone H3 dependent fatal-NETs. Further mechanically investigation found tumor derived NAMPT could induce Naged formation. Additionally, therapeutic interventions of Naged and its formation-linked pathways could effectively decrease breast cancer lung metastasis.

Conclusions

Naged exerts a vital role in breast cancer lung metastasis, and strategies targeting SIRT1-Naged-NETs axis show promise for translational application.

On Deep Landscape Exploration of COVID-19 Patients Cells and Severity Markers

COVID-19 is a disease with a spectrum of clinical responses ranging from moderate to critical. To study and control its effects, a large number of researchers are focused on two substantial aims. On the one hand, the discovery of diverse biomarkers to classify and potentially anticipate the disease severity of patients. These biomarkers could serve as a medical criterion to prioritize attention to those patients with higher prone to severe responses. On the other hand, understanding how the immune system orchestrates its responses in this spectrum of disease severities is a fundamental issue required to design new and optimized therapeutic strategies. In this work, using single-cell RNAseq of bronchoalveolar lavage fluid of nine patients with COVID-19 and three healthy controls, we contribute to both aspects. First, we presented computational supervised machine-learning models with high accuracy in classifying the disease severity (moderate and severe) in patients with COVID-19 starting from single-cell data from bronchoalveolar lavage fluid. Second, we identified regulatory mechanisms from the heterogeneous cell populations in the lungs microenvironment that correlated with different clinical responses. Given the results, patients with moderate COVID-19 symptoms showed an activation/inactivation profile for their analyzed cells leading to a sequential and innocuous immune response. In comparison, severe patients might be promoting cytotoxic and pro-inflammatory responses in a systemic fashion involving epithelial and immune cells without the possibility to develop viral clearance and immune memory. Consequently, we present an in-depth landscape analysis of how transcriptional factors and pathways from these heterogeneous populations can regulate their expression to promote or restrain an effective immune response directly linked to the patients prognosis.

In-silico analysis of myeloid cells across the animal kingdom reveals neutrophil evolution by colony-stimulating factors

Neutrophils constitute the largest population of phagocytic granulocytes in the blood of mammals. The development and function of neutrophils and monocytes is primarily governed by the granulocyte colony-stimulating factor receptor family (CSF3R/CSF3) and macrophage colony-stimulating factor receptor family (CSF1R/IL34/CSF1) respectively. Using various techniques this study considered how the emergence of receptor:ligand pairings shaped the distribution of blood myeloid cell populations. Comparative gene analysis supported the ancestral pairings of CSF1R/IL34 and CSF3R/CSF3, and the emergence of CSF1 later in lineages after the advent of Jawed/Jawless fish. Further analysis suggested that the emergence of CSF3 lead to reorganisation of granulocyte distribution between amphibian and early reptiles. However, the advent of endothermy likely contributed to the dominance of the neutrophil/heterophil in modern-day mammals and birds. In summary, we show that the emergence of CSF3R/CSF3 was a key factor in the subsequent evolution of the modern-day mammalian neutrophil.

Emerging roles for the nucleus during neutrophil signal relay and NETosis

The nucleus houses and protects genomic DNA, which is surrounded by the nuclear envelope. Owing to its size and stiffness, the nucleus is often a barrier to migration through confined spaces. Neutrophils are terminally differentiated, short-lived cells that migrate through tissues in response to injury and infections. The neutrophil nucleus is soft, multilobular, and exhibits altered levels of key nuclear envelope proteins. These alterations result in a multifunctional organelle that serves as a signaling hub during migration and NETosis, a process by which neutrophils release decondensed chromatin decorated with granular enzymes that entrap pathogens. In this review, we present emerging evidence suggesting that a unique, ambiguous cell-cycle state is critical for NETosis and migration. Finally, we discuss how the mechanisms underlying migration and NETosis are evolutionarily conserved.

Biological Roles of Neutrophil-Derived Granule Proteins and Cytokines

Neutrophils, the most abundant white blood cells in human circulation, entertain intense interactions with other leukocyte subsets, platelets, and stromal cells. Molecularly, such interactions are typically communicated through proteins generated during granulopoiesis, stored in granules, or produced on demand. Here, we provide an overview of the mammalian regulation of granule protein production in the bone marrow and the de novo synthesis of cytokines by neutrophils recruited to tissues. In addition, we discuss some of the known biological roles of these protein messengers, and how neutrophil-borne granule proteins and cytokines can synergize to modulate inflammation and tumor development. Decoding the neutrophil interactome is important for therapeutically neutralizing individual proteins to putatively dampen inflammation, or for delivering modified neutrophil-borne proteins to boost host defense.

The Neutrophil Nucleus: An Important Influence on Neutrophil Migration and Function

Neutrophil nuclear morphology has historically been used in haematology for neutrophil identification and characterisation, but its exact role in neutrophil function has remained enigmatic. During maturation, segmentation of the neutrophil nucleus into its mature, multi-lobulated shape is accompanied by distinct changes in nuclear envelope composition, resulting in a unique nucleus that is believed to be imbued with extraordinary nuclear flexibility. As a rate-limiting factor for cell migration, nuclear morphology and biomechanics are particularly important in the context of neutrophil migration during immune responses. Being an extremely plastic and fast migrating cell type, it is to be expected that neutrophils have an especially deformable nucleus. However, many questions still surround the dynamic capacities of the neutrophil nucleus, and which nuclear and cytoskeletal elements determine these dynamics. The biomechanics of the neutrophil nucleus should also be considered for their influences on the production of neutrophil extracellular traps (NETs), given this process sees the release of chromatin "nets" from nucleoplasm to extracellular space. Although past studies have investigated neutrophil nuclear composition and shape, in a new era of more sophisticated biomechanical and genetic techniques, 3D migration studies, and higher resolution microscopy we now have the ability to further investigate and understand neutrophil nuclear plasticity at an unprecedented level. This review addresses what is currently understood about neutrophil nuclear structure and its role in migration and the release of NETs, whilst highlighting open questions surrounding neutrophil nuclear dynamics.

Flow cytometry what you see matters: Enhanced clinical detection using image-based flow cytometry

Image-based flow cytometry combines the throughput of traditional flow cytometry with the ability to visually confirm findings and collect novel data that would not be possible otherwise. Since image-based flow cytometry borrows measurement parameters and analysis techniques from microscopy, it is possible to collect unique measures (i.e. nuclear translocation, co-localization, cellular synapse, cellular endocytosis, etc.) that would not be possible with traditional flow cytometry. The ability to collect unique outcomes has led many researchers to develop novel assays for the monitoring and detection of a variety of clinical conditions and diseases. In many cases, investigators have innovated and expanded classical assays to provide new insight regarding clinical conditions and chronic disease. Beyond human clinical applications, image-based flow cytometry has been used to monitor marine biology changes, nano-particles for solar cell production, and particle quality in pharmaceuticals. This review article summarizes work from the major scientists working in the field of image-based flow cytometry.