Influences of coexisting aged polystyrene microplastics on the ecological and health risks of cadmium in soils: A leachability and oral bioaccessibility based study.

Whether coexisting microplastics (MPs) affect the ecological and health risks of cadmium (Cd) in soils is a cutting-edge scientific issue. In this study, four typical Chinese soils were prepared as artificially Cd-contaminated soils with/without aged polystyrene (PS). TCLP and in vitro PBET model were used to determine the leachability (ecological risk) and oral bioaccessibility (human health risk) of soil Cd. The mechanisms by which MPs influence soil Cd were discussed from direct and indirect perspectives. Results showed that there was no significant difference in the leachability of soil Cd with/without aged PS. Additionally, aged PS led to a significant decrease in the bioaccessibility of soil Cd in gastric phase, but not in small intestinal phase. The increase in surface roughness and the new characteristic peaks (e.g., Si-O-Si) of aged PS directly accounted for the change in Cd bioaccessibility. The change in organic matter content indirectly accounted for the exceptional increase in Cd bioaccessibility of black soil with aged PS in small intestinal phase. Furthermore, the changes in cation exchange capacity and Cd mobility factor caused by aged PS explained the change in Cd leachability. These results contribute to a deeper understanding about environmental and public health in complicated emerging scenarios.

Supraclavicular brown adipocytes originate from Tbx1+ myoprogenitors.

Brown adipose tissue (BAT) dissipates energy as heat, contributing to temperature control, energy expenditure, and systemic homeostasis. In adult humans, BAT mainly exists in supraclavicular areas and its prevalence is associated with cardiometabolic health. However, the developmental origin of supraclavicular BAT remains unknown. Here, using genetic cell marking in mice, we demonstrate that supraclavicular brown adipocytes do not develop from the Pax3+/Myf5+ epaxial dermomyotome that gives rise to interscapular BAT (iBAT). Instead, the Tbx1+ lineage that specifies the pharyngeal mesoderm marks the majority of supraclavicular brown adipocytes. Tbx1Cre-mediated ablation of peroxisome proliferator-activated receptor gamma (PPARγ) or PR/SET Domain 16 (PRDM16), components of the transcriptional complex for brown fat determination, leads to supraclavicular BAT paucity or dysfunction, thus rendering mice more sensitive to cold exposure. Moreover, human deep neck BAT expresses higher levels of the TBX1 gene than subcutaneous neck white adipocytes. Taken together, our observations reveal location-specific developmental origins of BAT depots and call attention to Tbx1+ lineage cells when investigating human relevant supraclavicular BAT.

An immortal porcine preadipocyte cell strain for efficient production of cell-cultured fat.

Adding adipose cells to cell-cultured meat can provide a distinctive aroma and juicy texture similar to real meat. However, a significant challenge still exists in obtaining seed cells that can be propagated for long periods, maintain their adipogenic potential, and reduce production costs. In this study, we present a cell strain derived from immortalized porcine preadipocytes that can be subculture for over 40 passages without losing differentiation capacity. This cell strain can be differentiated within 3D bioscaffolds to generate cell-cultured fat using fewer chemicals and less serum. Additionally, it can be expanded and differentiated on microcarriers with upscaled culture to reduce costs and labor. Moreover, it can co-differentiate with muscle precursor cells, producing a pattern similar to real meat. Therefore, our cell strain provides an exceptional model for studying and producing cell-cultured fat.

O-GlcNAc glycosylation orchestrates fate decision and niche function of bone marrow stromal progenitors.

In mammals, interactions between the bone marrow (BM) stroma and hematopoietic progenitors contribute to bone-BM homeostasis. Perinatal bone growth and ossification provide a microenvironment for the transition to definitive hematopoiesis; however, mechanisms and interactions orchestrating the development of skeletal and hematopoietic systems remain largely unknown. Here, we establish intracellular O-linked ß-N-acetylglucosamine (O-GlcNAc) modification as a posttranslational switch that dictates the differentiation fate and niche function of early BM stromal cells (BMSCs). By modifying and activating RUNX2, O-GlcNAcylation promotes osteogenic differentiation of BMSCs and stromal IL-7 expression to support lymphopoiesis. In contrast, C/EBPß-dependent marrow adipogenesis and expression of myelopoietic stem cell factor (SCF) is inhibited by O-GlcNAcylation. Ablating O-GlcNAc transferase (OGT) in BMSCs leads to impaired bone formation, increased marrow adiposity, as well as defective B-cell lymphopoiesis and myeloid overproduction in mice. Thus, the balance of osteogenic and adipogenic differentiation of BMSCs is determined by reciprocal O-GlcNAc regulation of transcription factors, which simultaneously shapes the hematopoietic niche.

Risks of applying mobilising agents for remediation of arsenic-contaminated soils: Effects of dithionite-EDTA and citric acid on arsenic fractionation, leachability, oral bioavailability/bioaccessibility and speciation.

Arsenic (As) mobilisation assists in remediating As-contaminated soils but might increase ecological and health risks. In this study, risks of applying two mobilising agents were assessed, i.e. an emerging reducing-chelating composite agent [dithionite (Na2S2O4)-EDTA] and a classical low-molecular-weight organic acid (LMWOA) [citric acid (C6H8O7)]. Results showed that both agents induced sharp increase in leachability-based ecological risk of As. Interestingly, the two agents had opposite performances regarding health risks. Na2S2O4-EDTA significantly increased As relative bioavailability (RBA) to 1.83 times that in controls based on in vivo mouse model, and As bioaccessibility to 1.96, 1.65 and 1.20 times in gastric, small intestinal and colon phases based on in vitro PBET-SHIME model. Besides, it caused significant increase of highly toxic As(Ⅲ) in colon fluid. In contrast, C6H8O7 significantly reduced RBA and bioaccessibility of soil As in colon by 44.44% and 14.65%, respectively. Importantly, C6H8O7 restrained bioaccessible As(V) reduction and promoted bioaccessible As(Ⅲ) methylation, further reducing health risk. The phenomena could mainly be attributed to excessive metal components release from soil by C6H8O7 and gut microbiota metabolism of C6H8O7. In summary, C6H8O7 and similar LMWOAs are recommended. The study contributes to mobilising agent selection and development and provides a reference for managing remediation sites.

An OGT-STAT5 Axis in Regulatory T Cells Controls Energy and Iron Metabolism.

The immunosuppressive regulatory T (Treg) cells exert emerging effects on adipose tissue homeostasis and systemic metabolism. However, the metabolic regulation and effector mechanisms of Treg cells in coping with obesogenic insults are not fully understood. We have previously established an indispensable role of the O-linked N-Acetylglucosamine (O-GlcNAc) signaling in maintaining Treg cell identity and promoting Treg suppressor function, via STAT5 O-GlcNAcylation and activation. Here, we investigate the O-GlcNAc transferase (OGT)-STAT5 axis in driving the immunomodulatory function of Treg cells for metabolic homeostasis. Treg cell-specific OGT deficiency renders mice more vulnerable to high-fat diet (HFD)-induced adiposity and insulin resistance. Conversely, constitutive STAT5 activation in Treg cells confers protection against adipose tissue expansion and impaired glucose and insulin metabolism upon HFD feeding, in part by suppressing adipose lipid uptake and redistributing systemic iron storage. Treg cell function can be augmented by targeting the OGT-STAT5 axis to combat obesity and related metabolic disorders.

Brown adipose tissue involution associated with progressive restriction in progenitor competence.

Human brown adipose tissue (BAT) undergoes progressive involution. This involution process is not recapitulated in rodents, and the underlying mechanisms are poorly understood. Here we show that the interscapular BAT (iBAT) of rabbits whitens rapidly during early adulthood. The transcriptomic remodeling and identity switch of mature adipocytes are accompanied by loss of brown adipogenic competence of progenitors. Single-cell RNA sequencing reveals that rabbit and human iBAT progenitors highly express the FSTL1 gene. When iBAT involutes in rabbits, adipocyte progenitors reduce FSTL1 expression and are refractory to brown adipogenic recruitment. Conversely, FSTL1 is constitutively expressed in mouse iBAT to sustain WNT signaling and prevent involution. Progenitor incompetence and iBAT paucity can be induced in mice by genetic deletion of the Fstl1 gene or ablation of Fstl1+ progenitors. Our results highlight the hierarchy and dynamics of the BAT progenitor compartment and implicate the functional incompetence of FSTL1-expressing progenitors in BAT involution.

Epithelial STAT6 O-GlcNAcylation drives a concerted anti-helminth alarmin response dependent on tuft cell hyperplasia and Gasdermin C.

The epithelium is an integral component of mucosal barrier and host immunity. Following helminth infection, the intestinal epithelial cells secrete "alarmin" cytokines, such as interleukin-25 (IL-25) and IL-33, to initiate the type 2 immune responses for helminth expulsion and tolerance. However, it is unknown how helminth infection and the resulting cytokine milieu drive epithelial remodeling and orchestrate alarmin secretion. Here, we report that epithelial O-linked N-Acetylglucosamine (O-GlcNAc) protein modification was induced upon helminth infections. By modifying and activating the transcription factor STAT6, O-GlcNAc transferase promoted the transcription of lineage-defining Pou2f3 in tuft cell differentiation and IL-25 production. Meanwhile, STAT6 O-GlcNAcylation activated the expression of Gsdmc family genes. The membrane pore formed by GSDMC facilitated the unconventional secretion of IL-33. GSDMC-mediated IL-33 secretion was indispensable for effective anti-helminth immunity and contributed to induced intestinal inflammation. Protein O-GlcNAcylation can be harnessed for future treatment of type 2 inflammation-associated human diseases.

Protein O-GlcNAc Modification Links Dietary and Gut Microbial Cues to the Differentiation of Enteroendocrine L Cells.

Intestinal L cells regulate a wide range of metabolic processes, and L-cell dysfunction has been implicated in the pathogenesis of obesity and diabetes. However, it is incompletely understood how luminal signals are integrated to control the development of L cells. Here we show that food availability and gut microbiota-produced short-chain fatty acids control the posttranslational modification on intracellular proteins by O-linked ß-N-acetylglucosamine (O-GlcNAc) in intestinal epithelial cells. Via FOXO1 O-GlcNAcylation, O-GlcNAc transferase (OGT) suppresses expression of the lineage-specifying transcription factor Neurogenin 3 and, thus, L cell differentiation from enteroendocrine progenitors. Intestinal epithelial ablation of OGT in mice not only causes L cell hyperplasia and increased secretion of glucagon-like peptide 1 (GLP-1) but also disrupts gut microbial compositions, which notably contributes to decreased weight gain and improved glycemic control. Our results identify intestinal epithelial O-GlcNAc signaling as a brake on L cell development and function in response to nutritional and microbial cues.

Bone marrow adipose tissue-derived stem cell factor mediates metabolic regulation of hematopoiesis.

Hematopoiesis is dynamically regulated by metabolic cues in homeostatic and stressed conditions; however, the cellular and molecular mechanisms mediating the metabolic sensing and regulation remain largely obscure. Bone marrow adipose tissue remodels in various metabolic conditions and has been recently proposed as a niche for hematopoietic stem cells after irradiation. Here, we investigated the role of marrow adipose tissue-derived hematopoietic cytokine stem cell factor in unperturbed hematopoiesis by selectively ablating the Kitl gene from adipocytes and bone marrow stroma cells using Adipoq-Cre and Osx1-Cre, respectively. We found that both Adipoq-Kitl knockout (KO) and Osx1-Kitl KO mice diminished hematopoietic stem and progenitor cells and myeloid progenitors in the bone marrow and developed macrocytic anemia at the steady-state. The composition and differentiation of hematopoietic progenitor cells in the bone marrow dynamically responded to metabolic challenges including high fat diet, ß3-adrenergic activation, thermoneutrality, and aging. However, such responses, particularly within the myeloid compartment, were largely impaired in Adipoq-Kitl KO mice. Our data demonstrate that marrow adipose tissue provides stem cell factor essentially for hematopoiesis both at the steady state and upon metabolic stresses.

Decreased miR-128 and increased miR-21 synergistically cause podocyte injury in sepsis.

OBJECTIVE: Glomerular podocytes are injured in sepsis. We studied, in a sepsis patient, whether microRNAs (miRNAs) play a role in the podocyte injury. METHODS: Podocytes were cultured and treated with lipopolysaccharide (LPS). Filtration barrier function of podocyte was analyzed with albumin influx assay. Nephrin level was analyzed with reverse transcription polymerase chain reaction (RT-PCR) and western blot. MiRNAs were detected using miRNAs PCR Array and in situ hybridization. MiRNA target sites were evaluated with luciferase reporter assays. RESULTS: LPS impaired the filtration barrier function of podocytes. MiR-128 level was decreased and miR-21 level was increased in podocytes in vitro and in the sepsis patient. The decrease in miR-128 was sufficient to induce the loss of nephrin and the impairment of filtration barrier function, while the increase of miR-21 exacerbated the process. Snail and phosphatase and tensin homolog (PTEN) were identified as the targets of miR-128 and miR-21. Decreased miR-128 induced Snail expression, and the increased miR-21 stabilized Snail by regulating the PTEN/Akt/GSK3ß pathway. Supplementation of miR-128 and inhibition of miR-21 suppressed Snail expression and prevented the podocyte injury induced by LPS. CONCLUSION: Our study suggests that decreased miR-128 and increased miR-21 synergistically cause podocyte injury and are the potential therapeutic targets in sepsis.

MiR-107 induces TNF-α secretion in endothelial cells causing tubular cell injury in patients with septic acute kidney injury.

Activation of endothelial cells plays a key role in septic acute kidney injury (AKI). This study investigated the role of miRNA in endothelial-induced tubular cell injury in sepsis. Circulating endothelial cells (CECs) from septic AKI, non-septic AKI, septic non-AKI patients and healthy volunteers were isolated and cultured, and HK2 cells were exposed to CEC-conditioned medium. CEC-conditioned medium prepared from septic AKI patients led to cell shrinkage, decreased E-cadherin, the release of NAG and cell apoptosis in HK2 cells. TNF-α mediated the tubular cell injury induced by CEC-conditioned medium prepared from septic AKI patients. PCR array analysis detected that miR-107 was significantly increased in the CECs of septic AKI patients. MiR-107 was verified to target the 3'UTR of Dual-specificity phosphatase 7(DUSP7). Transfection of miR-107 ASO recovered the expression of DUSP7, suppressed the phosphorylation of ERK, and decreased the secretion of TNF-α in the CECs of septic AKI patients and in the peritubular endothelial cells of septic AKI mice. The inhibition of miR-107 prevented the decrease of E-cadherin, the release of NAG and cell apoptosis in HK2 cells exposed to CEC-conditioned medium prepared from septic AKI patients, and preserved the normal renal morphology and decreased the serum creatinine level in septic AKI mice. In conclusion, our study suggests that the increased miR-107 induces TNF-α secretion by targeting DUSP7 in endothelial cells, which may directly cause tubular cell injury in septic AKI.

Suppressor of Fused Chaperones Gli Proteins To Generate Transcriptional Responses to Sonic Hedgehog Signaling.

Cellular responses to the graded Sonic Hedgehog (Shh) morphogenic signal are orchestrated by three Gli genes that give rise to both transcription activators and repressors. An essential downstream regulator of the pathway, encoded by the tumor suppressor gene Suppressor of fused (Sufu), plays critical roles in the production, trafficking, and function of Gli proteins, but the mechanism remains controversial. Here, we show that Sufu is upregulated in active Shh responding tissues and accompanies Gli activators translocating into and Gli repressors out of the nucleus. Trafficking of Sufu to the primary cilium, potentiated by Gli activators but not repressors, was found to be coupled to its nuclear import. We have identified a nuclear export signal (NES) motif of Sufu in juxtaposition to the protein kinase A (PKA) and glycogen synthase kinase 3 (GSK3) dual phosphorylation sites and show that Sufu binds the chromatin with both Gli1 and Gli3. Close comparison of neural tube development among individual Ptch1-/-, Sufu-/-, and Ptch1-/-; Sufu-/- double mutant embryos indicates that Sufu is critical for the maximal activation of Shh signaling essential to the specification of the most-ventral neurons. These data define Sufu as a novel class of molecular chaperone required for every aspect of Gli regulation and function.

Requirement of Smurf-mediated endocytosis of Patched1 in sonic hedgehog signal reception.

Cell surface reception of Sonic hedgehog (Shh) must ensure that the graded morphogenic signal is interpreted accordingly in neighboring cells to specify tissue patterns during development. Here, we report endocytic sorting signals for the receptor Patched1 (Ptch1), comprising two 'PPXY' motifs, that direct it to degradation in lysosomes. These signals are recognized by two HECT-domain ubiquitin E3 ligases, Smurf1 and Smurf2, which are induced by Shh and become enriched in Caveolin-1 lipid rafts in association with Ptch1. Smurf-mediated endocytic turnover of Ptch1 is essential for its clearance from the primary cilium and pathway activation. Removal of both Smurfs completely abolishes the ability of Shh to sustain the proliferation of postnatal granule cell precursors in the cerebellum. These findings reveal a novel step in the Shh pathway activation as part of the Ptch1 negative feedback loop that precisely controls the signaling output in response to Shh gradient signal.

Mutation in the first Ig-like domain of Kit leads to JAK2 activation and myeloproliferation in mice.

Myeloproliferative neoplasms constitute a group of hematopoietic neoplasms at the myeloid stem cell level. Although mutations in the receptor tyrosine kinase KIT have been identified in patients with myeloproliferative neoplasm, the functional causality is unknown because of a lack of animal models. Here, we describe a mouse strain harboring a point mutation in the first Ig-like domain of Kit. Intriguingly, the mutant mice develop a myeloproliferative disorder with typical loss-of-function phenotypes in other tissues. The mutant Kit is incompletely N-glycosylated, shows compromised receptor dimerization, and down-regulates Akt and extracellular signal-regulating kinase 1/2 signaling. However, the mutation increases the association of Kit to Janus kinase (JAK)2 and hence the activation of JAK2. The ß common receptor of the gp140 family interacts and synergizes with Kit to promote JAK2 phosphorylation, which is further enhanced by the Kit mutation. Inhibition of JAK2 suppresses the proliferation of hematopoietic progenitors in vitro and partially rescues myeloproliferation in mice. Our data suggest that overactivation of JAK2 leads to myeloproliferation in Kit mutant mice and provide mechanistic insights for the diagnosis and treatment of myeloproliferative neoplasms in humans.

The miR-183∼96∼182 cluster promotes tumorigenesis in a mouse model of medulloblastoma.

Medulloblastoma is the most common malignant pediatric brain tumor. Some are thought to originate from cerebellar granule neuron progenitors (CGNPs) that fail to undergo normal cell cycle exit and differentiation. The contribution of microRNAs to the initiation and progression of medulloblastoma remains poorly understood. Increased expression of the miR-183∼96∼182 cluster of microRNAs has been noted in several aggressive subgroups. We identified that expression of miR-183∼96∼182 was higher in medulloblastomas with Pten gene loss in the background of the activated sonic hedgehog (Shh) signaling pathway. Ectopic miR-183∼96∼182 expression in CGNPs synergized with exogenous Shh to increase proliferation and its role depended on hedgehog signaling activation. Our findings suggest a new microRNA cluster, the miR-183∼96∼182, functionally collaborates with the Shh signaling pathway in the development of medulloblastomas in mice.

MicroRNA-214 promotes myogenic differentiation by facilitating exit from mitosis via down-regulation of proto-oncogene N-ras.

Vertebrate muscle differentiation is coordinated by an intricate network of transcription factors requiring proliferating myogenic precursors to withdraw irreversibly from the cell cycle. Recent studies have implicated a large number of microRNAs exerting another layer of control in many aspects of muscle differentiation. By annealing to short recognition sequences in the 3'-untranslated region, microRNAs attenuate target gene expression through translation repression or mRNA degradation. Here, we show that miR-214 promotes myogenic differentiation in mouse C2C12 myoblasts at a step preceding the induction of p21 and myogenin. Blocking miR-214 function with a 2'-O-methylated double-stranded inhibitor maintained C2C12 cells in the active cell cycle, thereby inhibiting the myogenic differentiation. By global gene expression profiling, we identified the proto-oncogene N-ras as one of miR-214 targets. Furthermore, manipulating the N-Ras level with small interfering RNA or adenovirus-mediated forced expression either augmented or attenuated the effect of miR-214, respectively. Thus, our data uncovered a novel microRNA-mediated mechanism that controls myogenic differentiation.