Highlights d Heterogeneity and plasticity of non-parenchymal cells in healthy and NASH liver d Landscape of intrahepatic ligand-receptor signaling at single-cell resolution d Emergence of Trem2+ NASH-associated macrophages (NAMs) in mouse and human NASH d Stellakine secretion and contractile response to vasoactive hormones by HSCs

The p53 transcription factor is a key tumor suppressor and a central regulator of the stress response. To ensure a robust and precise response to cellular signals, p53 gene expression must be tightly regulated from the transcriptional to the post-translational levels. Computational predictions suggest that several microRNAs are involved in the post-transcriptional regulation of p53. Here we demonstrate that miR-125b, a brain-enriched microRNA, is a bona fide negative regulator of p53 in both zebrafish and humans. miR-125b-mediated downregulation of p53 is strictly dependent on the binding of miR-125b to a microRNA response element in the 39 untranslated region of p53 mRNA. Overexpression of miR-125b represses the endogenous level of p53 protein and suppresses apoptosis in human neuroblastoma cells and human lung fibroblast cells. In contrast, knockdown of miR-125b elevates the level of p53 protein and induces apoptosis in human lung fibroblasts and in the zebrafish brain. This phenotype can be rescued significantly by either an ablation of endogenous p53 function or ectopic expression of miR-125b in zebrafish. Interestingly, miR-125b is down-regulated when zebrafish embryos are treated with g-irradiation or camptothecin, corresponding to the rapid increase in p53 protein in response to DNA damage. Ectopic expression of miR-125b suppresses the increase of p53 and stress-induced apoptosis. Together, our study demonstrates that miR-125b is an important negative regulator of p53 and p53-induced apoptosis during development and during the stress response.[Keywords: MicroRNA; p53; development; human; zebrafish] Supplemental material is available at http://www.genesdev.org.

CorrectionsCELL BIOLOGY. For the article ''miR-150, a microRNA expressed in mature B and T cells, blocks early B cell development when expressed prematurely,'' by Beiyan Zhou, Stephanie Wang, Christine Mayr, David P. Bartel, and Harvey F. Lodish, which appeared in issue 17, April 24, 2007, of Proc Natl Acad Sci USA (104:7080-7085; first published April 16, 2007; 10.1073͞pnas. 0702409104), the authors note that due to a printer's error, in Fig. 2 A and B, the x-axis labels in the Middle and Bottom panels appeared incorrectly. The corrected figure and its legend appear below. Fig. 2.Effects on short-term and long-term repopulation caused by overexpression of miR-150 and miR-195. (A and B) Lin Ϫ fetal liver cells from day 13.5-14.5 C57BL/6 mice (CD45.2) were prepared as described in Materials and Methods, spin-infected with miR-150 (Top), miR-195 (Middle), or empty MDH retroviral supernatant (Bottom), and transplanted into irradiated CD45.1 recipients. To evaluate the effects of short-term and long-term repopulation, peripheral blood samples were collected at 4 weeks (A) or 16 weeks (B) after transplantation. Donor-derived (CD45.2) cell lineages were examined by using antibodies against specific cell lineage surface markers followed by FACS analysis: B cells (CD19 ϩ ), T cells (CD4 ϩ or CD8 ϩ ), and myeloid cells (CD11b ϩ or Gr-1 ϩ ). The percentage of each cell lineage in either the GFP Ϫ or GFP ϩ population from each mouse was defined as that specific cell lineage proportion in the peripheral blood. The mean value for each group was the average of all cell proportions from 20 mice in two independent transplantations. (C) The long-term repopulation effects of the transplantation in the spleen (Left) and lymph nodes (Right) of miR-150 mice were examined as described. Statistics from each cell lineage were calculated by the Mann-Whitney test. Significance was defined as follows: * , P Ͻ 0.05; ** , P Ͻ 0.001. Band T cells are derived from hematopoietic stem cells, which reside in the bone marrow of adult mice and the liver of embryos. In particular, the bone marrow is the major site of B cell development in adult mice. B cells are derived from a common lymphoid progenitor (CLP) cell (lin Ϫ c-kit low Sca-1 low IL-7R ϩ ) (1), which is limited in its ability to develop into T lymphocytes but is fully capable of developing into B cells. B cell development is divided into several successive steps as judged by surface markers and rearrangement of immunoglobin genes. The first B lineage-restricted cells are termed pro-B cells, which initiate rearrangement at the Ig heavy-chain (IgH) locus: D H to J H joining at the early pro-B cell stage, followed by V H to DJ H joining at the late pro-B cell stage (2, 3). The immunoglobin heavy chain ( chain) then assembles with a surrogate light chain (SLC) and forms the pre-B cell receptor (pre-BCR) to mediate expansion of pre-B cells. When the SLC is replaced by a successfully rearranged immunoglobin light chain (IgL) to form IgM, the cells become immature B cells (3-5).Many cytoki...

MicroRNAs (miRNAs) are an abundant class of evolutionarily conserved small non-coding RNAs that are thought to control gene expression by targeting mRNAs for degradation or translational repression. Emerging evidence suggests that miRNA-mediated gene regulation represents a fundamental layer of genetic programmes at the post-transcriptional level and has diverse functional roles in animals. Here, we provide an overview of the mechanisms by which miRNAs regulate gene expression, with specific focus on the role of miRNAs in regulating the development of immune cells and in modulating innate and adaptive immune responses.

MicroRNAs (miRNAs) are a class of small noncoding RNAs that regulate gene expression at the posttranscriptional level. Research on miRNAs has highlighted their importance in neural development, but the specific functions of neurally enriched miRNAs remain poorly understood. We report here the expression profile of miRNAs during neuronal differentiation in the human neuroblastoma cell line SH-SY5Y. Six miRNAs were significantly upregulated during differentiation induced by all-trans-retinoic acid and brain-derived neurotrophic factor. We demonstrated that the ectopic expression of either miR-124a or miR-125b increases the percentage of differentiated SH-SY5Y cells with neurite outgrowth. Subsequently, we focused our functional analysis on miR-125b and demonstrated the important role of this miRNA in both the spontaneous and induced differentiations of SH-SH5Y cells. miR-125b is also upregulated during the differentiation of human neural progenitor ReNcell VM cells, and miR-125b ectopic expression significantly promotes the neurite outgrowth of these cells. To identify the targets of miR-125b regulation, we profiled the global changes in gene expression following miR-125b ectopic expression in SH-SY5Y cells. miR-125b represses 164 genes that contain the seed match sequence of the miRNA and/or that are predicted to be direct targets of miR-125b by conventional methods. Pathway analysis suggests that a subset of miR-125b-repressed targets antagonizes neuronal genes in several neurogenic pathways, thereby mediating the positive effect of miR125b on neuronal differentiation. We have further validated the binding of miR-125b to the miRNA response elements of 10 selected mRNA targets. Together, we report here for the first time the important role of miR-125b in human neuronal differentiation.

Background-Macrophage activation plays a crucial role in regulating adipose tissue inflammation and is a major contributor to the pathogenesis of obesity-associated cardiovascular diseases. On various types of stimuli, macrophages respond with either classic (M1) or alternative (M2) activation. M1-and M2-mediated signaling pathways and corresponding cytokine production profiles are not completely understood. The discovery of microRNAs provides a new opportunity to understand this complicated but crucial network for macrophage activation and adipose tissue function. Methods and Results-We have examined the activity of microRNA-223 (miR-223) and its role in controlling macrophage functions in adipose tissue inflammation and systemic insulin resistance. miR-223 Ϫ/Ϫ mice on a high-fat diet exhibited an increased severity of systemic insulin resistance compared with wild-type mice that was accompanied by a marked increase in adipose tissue inflammation. The specific regulatory effects of miR-223 in myeloid cell-mediated regulation of adipose tissue inflammation and insulin resistance were then confirmed by transplantation analysis. Moreover, using bone marrow-derived macrophages, we demonstrated that miR-223 is a novel regulator of macrophage polarization, which suppresses classic proinflammatory pathways and enhances the alternative antiinflammatory responses. In addition, we identified Pknox1 as a genuine miR-223 target gene and an essential regulator for macrophage polarization. Conclusion-For the first time, this study demonstrates that miR-223 acts to inhibit Pknox1, suppressing proinflammatory activation of macrophages; thus, it is a crucial regulator of macrophage polarization and protects against diet-induced adipose tissue inflammatory response and systemic insulin resistance. (Circulation. 2012;125:2892-2903.)Key Words: adipose tissue Ⅲ insulin resistance Ⅲ macrophages Ⅲ microRNAs A dipose tissue inflammation is a hallmark of obesity and a causal factor of metabolic disorders such as insulin resistance 1-5 and a wide variety of metabolic diseases, including atherosclerosis and type 2 diabetes mellitus. 4 -6 Mice fed a high-fat diet (HFD) frequently develop chronic low-grade inflammation within adipose tissues, characterized by increased infiltration of immune cells and the production of proinflammatory cytokines. 1,2 Consequently, adipocytes produce a number of inflammatory mediators that contribute to atherosclerotic cardiovascular disease. 7,8 Importantly, elevated adipose tissue inflammation is a significant factor contributing to systemic insulin resistance, 9 -14 which is an additional risk factor for cardiovascular disease through both inflammation-dependent and -independent mechanisms. Given the importance of adipose tissue inflammation in metabolic diseases, there is a critical need to better understand the mechanisms underlying these inflammatory processes. Editorial see p 2815 Clinical Perspective on p 2903Several reports demonstrate that macrophages are key regulators of adipose tissue inflammat...

MicroRNA miR-125b has been implicated in several kinds of leukemia. The chromosomal translocation t(2;11)(p21;q23) found in patients with myelodysplasia and acute myeloid leukemia leads to an overexpression of miR-125b of up to 90-fold normal. Moreover, miR-125b is also up-regulated in patients with B-cell acute lymphoblastic leukemia carrying the t(11;14)(q24;q32) translocation. To decipher the presumed oncogenic mechanism of miR-125b, we used transplantation experiments in mice. All mice transplanted with fetal liver cells ectopically expressing miR-125b showed an increase in white blood cell count, in particular in neutrophils and monocytes, associated with a macrocytic anemia. Among these mice, half died of B-cell acute lymphoblastic leukemia, T-cell acute lymphoblastic leukemia, or a myeloproliferative neoplasm, suggesting an important role for miR-125b in early hematopoiesis. Furthermore, coexpression of miR-125b and the BCR-ABL fusion gene in transplanted cells accelerated the development of leukemia in mice, compared with control mice expressing only BCR-ABL, suggesting that miR125b confers a proliferative advantage to the leukemic cells. Thus, we show that overexpression of miR-125b is sufficient both to shorten the latency of BCR-ABL-induced leukemia and to independently induce leukemia in a mouse model.

The article describes a readily easy adaptive in vitro model to investigate macrophage polarization. In the presence of GM-CSF/M-CSF, hematopoietic stem/progenitor cells from the bone marrow are directed into monocytic differentiation, followed by M1 or M2 stimulation. The activation status can be tracked by changes in cell surface antigens, gene expression and cell signaling pathways. Video LinkThe video component of this article can be found at