Stages Of Terminal Differentiation Research Articles

Identification and characterization of the novel Col10a1 regulatory mechanism during chondrocyte hypertrophic differentiation.

The majority of human skeleton develops through the endochondral pathway, in which cartilage-forming chondrocytes proliferate and enlarge into hypertrophic chondrocytes that eventually undergo apoptosis and are replaced by bone. Although at a terminal differentiation stage, hypertrophic chondrocytes have been implicated as the principal engine of bone growth. Abnormal chondrocyte hypertrophy has been seen in many skeletal dysplasia and osteoarthritis. Meanwhile, as a specific marker of hypertrophic chondrocytes, the type X collagen gene (COL10A1) is also critical for endochondral bone formation, as mutation and altered COL10A1 expression are often accompanied by abnormal chondrocyte hypertrophy in many skeletal diseases. However, how the type X collagen gene is regulated during chondrocyte hypertrophy has not been fully elucidated. We have recently demonstrated that Runx2 interaction with a 150-bp mouse Col10a1 cis-enhancer is required but not sufficient for its hypertrophic chondrocyte-specific reporter expression in transgenic mice, suggesting requirement of additional Col10a1 regulators. In this study, we report in silico sequence analysis of this 150-bp enhancer and identification of its multiple binding factors, including AP1, MEF2, NFAT, Runx1 and TBX5. Using this enhancer as bait, we performed yeast one-hybrid assay and identified multiple candidate Col10a1-interacting genes, including cyclooxygenase 1 (Cox-1) and Cox-2. We have also performed mass spectrometry analysis and detected EF1-alpha, Fus, GdF7 and Runx3 as components of the specific complex formed by the cis-enhancer and nuclear extracts from hypertrophic MCT (mouse chondrocytes immortalized with large T antigen) cells that express Col10a1 abundantly. Notably, some of the candidate genes are differentially expressed in hypertrophic MCT cells and have been associated with chondrocyte hypertrophy and Runx2, an indispensible Col10a1 regulator. Intriguingly, we detected high-level Cox-2 expression in hypertrophic MCT cells. Electrophoretic mobility shift assay and chromatin immunoprecipitation assays confirmed the interaction between Cox-2 and Col10a1 cis-enhancer, supporting its role as a candidate Col10a1 regulator. Together, our data support a Cox-2-containing, Runx2-centered Col10a1 regulatory mechanism, during chondrocyte hypertrophic differentiation.

Pregnancy-secreted Acid phosphatase, uteroferrin, enhances fetal erythropoiesis.

Uteroferrin (UF) is a progesterone-induced acid phosphatase produced by uterine glandular epithelia in mammals during pregnancy and targeted to sites of hematopoiesis throughout pregnancy. The expression pattern of UF is coordinated with early fetal hematopoietic development in the yolk sac and then liver, spleen, and bone to prevent anemia in fetuses. Our previous studies suggested that UF exerts stimulatory impacts on hematopoietic progenitor cells. However, the precise role and thereby the mechanism of action of UF on hematopoiesis have not been investigated previously. Here, we report that UF is a potent regulator that can greatly enhance fetal erythropoiesis. Using primary fetal liver hematopoietic cells, we observed a synergistic stimulatory effect of UF with erythropoietin and other growth factors on both burst-forming unit-erythroid and colony-forming unit-erythroid formation. Further, we demonstrated that UF enhanced erythropoiesis at terminal stages using an in vitro culture system. Surveying genes that are crucial for erythrocyte formation at various stages revealed that UF, along with erythropoietin, up-regulated transcription factors required for terminal erythrocyte differentiation and genes required for synthesis of hemoglobin. Collectively, our results demonstrate that UF is a cytokine secreted by uterine glands in response to progesterone that promotes fetal erythropoiesis at various stages of pregnancy, including burst-forming unit-erythroid and colony-forming unit-erythroid progenitor cells and terminal stages of differentiation of hematopoietic cells in the erythroid lineage.

Molecular ties between the cell cycle and differentiation in embryonic stem cells.

Attainment of the differentiated state during the final stages of somatic cell differentiation is closely tied to cell cycle progression. Much less is known about the role of the cell cycle at very early stages of embryonic development. Here, we show that molecular pathways involving the cell cycle can be engineered to strongly affect embryonic stem cell differentiation at early stages in vitro. Strategies based on perturbing these pathways can shorten the rate and simplify the lineage path of ES differentiation. These results make it likely that pathways involving cell proliferation intersect at various points with pathways that regulate cell lineages in embryos and demonstrate that this knowledge can be used profitably to guide the path and effectiveness of cell differentiation of pluripotent cells.

Global transcriptome analyses of human and murine terminal erythroid differentiation

AbstractWe recently developed fluorescence-activated cell sorting (FACS)-based methods to purify morphologically and functionally discrete populations of cells, each representing specific stages of terminal erythroid differentiation. We used these techniques to obtain pure populations of both human and murine erythroblasts at distinct developmental stages. RNA was prepared from these cells and subjected to RNA sequencing analyses, creating unbiased, stage-specific transcriptomes. Tight clustering of transcriptomes from differing stages, even between biologically different replicates, validated the utility of the FACS-based assays. Bioinformatic analyses revealed that there were marked differences between differentiation stages, with both shared and dissimilar gene expression profiles defining each stage within transcriptional space. There were vast temporal changes in gene expression across the differentiation stages, with each stage exhibiting unique transcriptomes. Clustering and network analyses revealed that varying stage-specific patterns of expression observed across differentiation were enriched for genes of differing function. Numerous differences were present between human and murine transcriptomes, with significant variation in the global patterns of gene expression. These data provide a significant resource for studies of normal and perturbed erythropoiesis, allowing a deeper understanding of mechanisms of erythroid development in various inherited and acquired erythroid disorders.

In Vitro Assessment of IL-4- or IL-13-Mediated Changes in the Structural Components of Keratinocytes in Mice and Humans

T helper type 2 (Th2) cytokines, IL-4 and IL-13, attenuate the expression of genes that regulate epidermal cellular structures and the barrier function at the terminal stage of keratinocyte differentiation. However, whether these Th2 cytokines act at earlier stages remains unknown. We investigated the roles of cytokines in expression levels of mRNAs and/or proteins in primary mouse keratinocytes and human keratinocyte HaCaT cells at earlier stages. We showed that IL-4 downregulated the expression levels of Krt1, Krt10, Dsg1, and Dsc1 via IL-4Rα- and signal transducer and activator of transcription factor 6 (STAT6)-dependent mechanisms in differentiating mouse keratinocytes at early stages. As the expression levels of keratin-1 and -10 in the keratinocytes transiently expressing an active form of STAT6 were not downregulated, STAT6 and other IL-4-induced molecules may synergistically regulate this expression. The restoration of the downregulated expression levels of Krt1 and Krt10 induced by IL-4 with the MEK (mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase kinase) inhibitor U0126 indicated the involvement of the p44/42 MAPK signaling pathway in the attenuated expression. IL-13 also downregulated the expression of the four genes. Furthermore, IL-4 or IL-13 caused the downregulation of these genes in HaCaT cells and promoted the fragmentation of cell sheets with mechanical stress. Our results showed that IL-4 or IL-13 acted on differentiating keratinocytes in vitro at early stages to attenuate the gene expression.

PRRX1 and PRRX2 distinctively participate in pituitary organogenesis and a cell-supply system.

Paired-related homeobox transcription factors, PRRX1 and PRRX2, are known to be important factors for craniofacial and limb morphogenesis. We recently cloned Prrx2 from the porcine adult pituitary cDNA library and found that only PRRX1 is present in the rat embryonic pituitary. In this study, we re-investigated the temporospatial expression and localization of PRRX1 and PRRX2 in the rat pituitary throughout life. The persistent expression of Prrx1 was ascertained after the middle stage of embryonic development, whereas significant expression of Prrx2 was found only in the postnatal pituitary. Immunohistochemistry confirmed that PRRX1-positive cells appeared inside the pituitary on embryonic day 16.5 in the marginal cell layer (MCL), a pituitary stem/progenitor cell niche, and the expanding parenchyma of the anterior pituitary. In contrast, PRRX2-positive cells first appeared in the anterior lobe and intermediate lobe sides of the MCL around postnatal day 30 when the postnatal pituitary growth wave had almost terminated. Immunostaining for PRRX1 with a stem/progenitor cell marker SOX2, a pituitary progenitor marker PROP1, or pituitary hormones revealed that PRRX1 localized in cells in the transition process from the multipotent progenitor stage to the early stage of terminal differentiation throughout life. PRRX2 emerged in cells positive for SOX2 but negative for PROP1 in the anterior and intermediate lobe sides of the postnatal MCL. Thus, PRRX1 and PRRX2 might participate distinctly in pituitary organogenesis and the postnatal cell-supply system.

Fucoidan Promotes Early Step of Cardiac Differentiation from Human Embryonic Stem Cells and Long-Term Maintenance of Beating Areas

Somatic stem cells require specific niches and three-dimensional scaffolds provide ways to mimic this microenvironment. Here, we studied a scaffold based on Fucoidan, a sulfated polysaccharide known to influence morphogen gradients during embryonic development, to support human embryonic stem cells (hESCs) differentiation toward the cardiac lineage. A macroporous (pore 200 μm) Fucoidan scaffold was selected to support hESCs attachment and proliferation. Using a protocol based on the cardiogenic morphogen bone morphogenic protein 2 (BMP2) and transforming growth factor (TGFβ) followed by tumor necrosis factor (TNFα), an effector of cardiopoietic priming, we examined the cardiac differentiation in the scaffold compared to culture dishes and embryoid bodies (EBs). At day 8, Fucoidan scaffolds supported a significantly higher expression of the 3 genes encoding for transcription factors marking the early step of embryonic cardiac differentiation NKX2.5 (p<0.05), MEF2C (p<0.01), and GATA4 (p<0.01), confirmed by flow cytometry analysis for MEF2C and NKX2.5. The ability of Fucoidan scaffolds to locally concentrate and slowly release TGFβ and TNFα was confirmed by Luminex technology. We also found that Fucoidan scaffolds supported the late stage of embryonic cardiac differentiation marked by a significantly higher atrial natriuretic factor (ANF) expression (p<0.001), although only rare beating areas were observed. We postulated that absence of mechanical stress in the soft hydrogel impaired sarcomere formation, as confirmed by molecular analysis of the cardiac muscle myosin MYH6 and immunohistological staining of sarcomeric α-actinin. Nevertheless, Fucoidan scaffolds contributed to the development of thin filaments connecting beating areas through promotion of smooth muscle cells, thus enabling maintenance of beating areas for up to 6 months. In conclusion, Fucoidan scaffolds appear as a very promising biomaterial to control cardiac differentiation from hESCs that could be further combined with mechanical stress to promote sarcomere formation at terminal stages of differentiation.

MicroRNA-143 regulates adipogenesis by modulating the MAP2K5-ERK5 signaling.

A better understanding of the molecular mechanisms that regulate adipose tissue-derived stromal cell (ADSC) differentiation could provide new insight into some adipose-tissue-related disease. The differentiation of ADSCs into adipocytes is a complex physiological process that includes clonal expansion, growth arrest, and terminal differentiation. Here the role of microRNA-143 (miR-143) during ADSC adipogenic differentiation was systematically investigated. We found that miR-143 expression was transiently decreased after adipogenic induction while increased from day 3 and peaked on day 7 after induction. We show for the first time that the role of miR-143 is not consistent in the differentiation process. The regulatory role depends on the differentiation stage that miR-143 acts on. When miR-143 is overexpressed during the clonal expansion stage, the adipogenic differentiation of ADSCs is inhibited, whereas the overexpression of miR-143 during the growth arrest stage or terminal differentiation stage promotes differentiation. Further we firstly demonstrate that miR-143 plays the modulational role by directly repressing MAP2K5, a key member of the MAPKK family in the MAPK signaling pathway. These findings suggest that miR-143 plays an important role in adipose tissue formation, with special implications for some metabolic disease in which the amount and/or function of adipose tissue is altered.

Dual Effect of Chrysanthemum indicum Extract to Stimulate Osteoblast Differentiation and Inhibit Osteoclast Formation and Resorption In Vitro

The risk of bone-related diseases increases due to the imbalance between bone resorption and bone formation by osteoclasts and osteoblasts, respectively. The goal in the development of antiosteoporotic treatments is an agent that will improve bone through simultaneous osteoblast stimulation and osteoclast inhibition without undesirable side effects. To achieve this goal, numerous studies have been performed to identify novel approaches using natural oriental herbs to treat bone metabolic diseases. In the present study, we investigated the effect of Chrysanthemum indicum extract (CIE) on the differentiation of osteoclastic and osteoblastic cells. CIE inhibited the formation of TRAP-positive mature osteoclasts and of filamentous-actin rings and disrupted the bone-resorbing activity of mature osteoclasts in a dose-dependent manner. CIE strongly inhibited Akt, GSK3β, and IκB phosphorylation in RANKL-stimulated bone marrow macrophages and did not show any effects on MAP kinases, including p38, ERK, and JNK. Interestingly, CIE also enhanced primary osteoblast differentiation via upregulation of the expression of alkaline phosphatase and the level of extracellular calcium concentrations during the early and terminal stages of differentiation, respectively. Our results revealed that CIE could have a potential therapeutic role in bone-related disorders through its dual effects on osteoclast and osteoblast differentiation.

Role Of Transferrin In Recovery From Phlebotomy In Iron Replete Or Iron Deficient Mice

The most common reason for deferral of blood donation is low hemoglobin concentration and anemia. Furthermore, repeated donations, especially in young females, may lead to iron deficiency, drop of hemoglobin, and consequent iron deficiency anemia. Recent data suggests that iron deficiency, in the absence of anemia, may be associated with symptoms in otherwise healthy individuals. Our previous findings suggested that additional transferrin ameliorates anemia in mouse models of β-thalassemia; this effect appears driven by an increase in the number of circulating red blood cell (RBC) by extending RBC survival (Li Nat Med 2010). We hypothesized that exogenous transferrin increases RBC count and enables a more rapid recovery after phlebotomy. To test this hypothesis, C57 mice were fed an iron replete (35ppm iron) and iron deficient (2.5ppm iron) diet for 3 months to simulate the human condition. Mice were phlebotomized an average of 220ul of blood weekly for four weeks. Additionally, all mice received intraperitoneal (IP) injection of either of 10mg of human apo-transferrin (apo-Tf) (200 ul volume) or 200ul PBS daily Monday – Friday for 4 weeks (in total 20 days of injection). Mice (n=4/group) were sacrificed and samples analyzed at the end of the 4 weeks. RBC survival was evaluated using an in vivo biotin avidin assay previously described (Li Nat Med 2010). We analyzed all RBC indices using ADVIA 120 (Bayer). MCV decreased in phlebotomized mice on 2.5ppm compared to 35ppm diet (p=0.012) and after apo-Tf injection (p<0.05 in 2.5ppm diet, and p<0.001 in 35ppm diet). Reticulocyte counts increased by 50% in apo-Tf treated compared to PBS treated phlebotomized mice on 2.5ppm diet (p=0.006). Apo-Tf injections also resulted in an increase in RBC counts in phlebotomized mice on 35ppm diet (p=0.056). Furthermore, using antibodies to CD44 and TER119 in flow cytometry (Chen PNAS 2010), we assessed the proportion of erythroid precursors at all stages of terminal erythroid differentiation. Apo-Tf injections result in more erythroid precursors in spleen and bone marrow (p<0.05) in phlebotomized mice on 2.5ppm or 35ppm diets without changes in the degree of apoptosis or quantity of reactive oxygen species. Mice on 2.5ppm diet had smaller spleens relative to 35ppm diet (0.002 vs. 0.004 spleen / body weight, p=0.05) that increased as a consequence of apo-Tf injection (0.003 vs. 0.002 spleen / body weight, p=0.02). No differences in spleen size or spleen / body weight is observed in apo-Tf treated mice on 35ppm diet. Immunohistochemistry of spleen samples using anti-TER119 antibodies revealed more extramedullary erythropoiesis in all apo-Tf treated mice. Lastly, no difference in RBC survival was observed in mice as a consequence of diet or injection. Taken together, our data suggest that exogenous apo-Tf in recurrently phlebotomized mice on iron deficient diet stimulates erythropoiesis without a direct effect on RBC survival. This data provides initial evidence that exogenous apo-Tf accelerates recovery from phlebotomy especially in iron replete conditions, without evidence of harm in iron deficiency. The molecular mechanisms underlying the effect of iron availability and iron delivery on different stages of erythroid differentiation requires further analysis. Disclosures:No relevant conflicts of interest to declare.

Isoniazid suppresses antioxidant response element activities and impairs adipogenesis in mouse and human preadipocytes

Transcriptional signaling through the antioxidant response element (ARE), orchestrated by the Nuclear factor E2-related factor 2 (Nrf2), is a major cellular defense mechanism against oxidative or electrophilic stress. Here, we reported that isoniazid (INH), a widely used antitubercular drug, displays a substantial inhibitory property against ARE activities in diverse mouse and human cells. In 3T3-L1 preadipocytes, INH concentration-dependently suppressed the ARE-luciferase reporter activity and mRNA expression of various ARE-dependent antioxidant genes under basal and oxidative stressed conditions. In keeping with our previous findings that Nrf2-ARE plays a critical role in adipogenesis by regulating expression of CCAAT/enhancer-binding protein β (C/EBPβ) and peroxisome proliferator-activated receptor γ (PPARγ), suppression of ARE signaling by INH hampered adipogenic differentiation of 3T3-L1 cells and human adipose-derived stem cells (ADSCs). Following adipogenesis induced by hormonal cocktails, INH-treated 3T3-L1 cells and ADSCs displayed significantly reduced levels of lipid accumulation and attenuated expression of C/EBPα and PPARγ. Time-course studies in 3T3-L1 cells revealed that inhibition of adipogenesis by INH occurred in the early stage of terminal adipogenic differentiation, where reduced expression of C/EBPβ and C/EBPδ was observed. To our knowledge, the present study is the first to demonstrate that INH suppresses ARE signaling and interrupts with the transcriptional network of adipogenesis, leading to impaired adipogenic differentiation. The inhibition of ARE signaling may be a potential underlying mechanism by which INH attenuates cellular antioxidant response contributing to various complications.

Reproductive competence: a recurrent logic module in eukaryotic development.

Developmental competence is the ability to differentiate in response to an appropriate stimulus, as first elaborated by Waddington in relation to organs and tissues. Competence thresholds operate at all levels of biological systems from the molecular (e.g. the cell cycle) to the ontological (e.g. metamorphosis and reproduction). Reproductive competence, an organismal process, is well studied in mammals (sexual maturity) and plants (vegetative phase change), though far less than later stages of terminal differentiation. The phenomenon has also been documented in multiple species of multicellular fungi, mostly in early, disparate literature, providing a clear example of physiological differentiation in the absence of morphological change. This review brings together data on reproductive competence in Ascomycete fungi, particularly the model filamentous fungus Aspergillus nidulans, contrasting mechanisms within Unikonts and plants. We posit reproductive competence is an elementary logic module necessary for coordinated development of multicellular organisms or functional units. This includes unitary multicellular life as well as colonial species both unicellular and multicellular (e.g. social insects such as ants). We discuss adaptive hypotheses for developmental and reproductive competence systems and suggest experimental work to address the evolutionary origins, generality and genetic basis of competence in the fungal kingdom.

Dynamic Rewiring of the Drosophila Retinal Determination Network Switches Its Function from Selector to Differentiation

Organ development is directed by selector gene networks. Eye development in the fruit fly Drosophila melanogaster is driven by the highly conserved selector gene network referred to as the “retinal determination gene network,” composed of approximately 20 factors, whose core comprises twin of eyeless (toy), eyeless (ey), sine oculis (so), dachshund (dac), and eyes absent (eya). These genes encode transcriptional regulators that are each necessary for normal eye development, and sufficient to direct ectopic eye development when misexpressed. While it is well documented that the downstream genes so, eya, and dac are necessary not only during early growth and determination stages but also during the differentiation phase of retinal development, it remains unknown how the retinal determination gene network terminates its functions in determination and begins to promote differentiation. Here, we identify a switch in the regulation of ey by the downstream retinal determination genes, which is essential for the transition from determination to differentiation. We found that central to the transition is a switch from positive regulation of ey transcription to negative regulation and that both types of regulation require so. Our results suggest a model in which the retinal determination gene network is rewired to end the growth and determination stage of eye development and trigger terminal differentiation. We conclude that changes in the regulatory relationships among members of the retinal determination gene network are a driving force for key transitions in retinal development.

Notch2-dependent classical dendritic cells orchestrate intestinal immunity to attaching-and-effacing bacterial pathogens

Defense against attaching and effacing (A/E) bacteria requires the sequential generation of interleukin 23 (IL-23) and IL-22 to induce protective mucosal responses. While CD4+ and NKp46+ innate lymphoid cells (ILCs) are the critical source of IL-22 during infection, the precise source of IL-23 is unclear. We used genetic techniques to deplete specific subsets of classical dendritic cells (cDCs) and analyzed immunity to the A/E pathogen Citrobacter rodentium. We found that Notch2 controlled the terminal stage of cDC differentiation. Notch2-dependent intestinal CD11b+ cDCs, but not Batf3-dependent CD103+ cDCs, were an obligate source of IL-23 required to survive C. rodentium infection. These results provide the first demonstration of a non-redundant function of CD11b+ cDCs in response to pathogens in vivo.

Study of the clonal origin and development of MDS by FISH analysis of dysplasia cells in bone marrow of patients with MDS

This study was purpose to explore whether the dysplasia of myelodysplastic syndromes (MDS) is unspecific feature or results of the abnormal clone, and to provide the evaluation of abnormal clone changes in bone marrow cells of MDS patients. The dysplasia cells in bone marrow smears was analyzed by morphologic observation, the clonal origin and development in 16 cases of MDS with abnormality of chromosome karyotypes were investigated by FISH combined with morphologic observation. The results found that both the dysplastic and nondysplastic bone cells displayed abnormal clones in the erythroid and granulocytic cells. The dysplastic bone marrow cells displayed more abnormal clones than the nondysplastic bone marrow cells in most of the patients, and the abnormal clones displayed more dysplastic cells than the normal clones. Most of the dysplastic and nondysplastic megakaryocytes were derived from abnormal clones. The abnormal clone showed a decreasing trend from the primitive stage to the terminal stage of cell differentiation. It is concluded that there is a correlation between the dysplastic cells and the abnormal clones in MDS, but the dysplasia of bone marrow cells is not a specific feature. The abnormal clones can differentiate into mature granulocytes and erythrocytes, and can be in coexistence with cells originated from the normal clones.

An inhibitory role of progerin in the gene induction network of adipocyte differentiation from iPS cells.

Lipodystrophies, characterized by partial or complete loss of adipose tissue, have been associated with mutations in the lamin A gene. It remains unclear how lamin A mutants interfere with adipose tissue formation. Hutchinson-Gilford progeria syndrome (HGPS) presents the most severe form of lamin A-associated diseases, whose patients show a complete loss of subcutaneous fat. Using iPSCs reprogrammed from HGPS fibroblasts, we induced adipocyte formation from iPSC derived embryoid bodies or from iPSC derived mesenchymal stem cells. Both approaches revealed a severe lipid storage defect in HGPS cells at late differentiation stage, faithfully recapitulating HGPS patient phenotype. Expression analysis further indicated that progerin inhibited the transcription activation of PPARγ2 and C/EBPα, but had little effects on the early adipogenic regulators. Our experiments demonstrate two comparable approaches of in vitro modeling lipodystrophies with patient-specific iPSCs, and support a regulatory role of lamin A in the terminal differentiation stage of adipogenesis.

Effect of radiation on the Notch signaling pathway in osteoblasts

Notch signaling has been shown to be important in osteoblast differentiation. Therapeutic radiation has been shown to alter the skeletal system, yet little information is available on the changes in Notch signaling in irradiated osteoblasts. The purpose of this study was to analyze the effect of radiation therapy with 2 and 4Gy on Notch signaling in osteoblasts. In order to assess the radiation damage on osteoblast differentiation, total RNA and protein were collected three days after exposure to radiation. The effects of radiation on Notch signaling at the early and terminal stages of osteoblastic MC3T3-E1 cell differentiation was analyzed by qRT-PCR and western blot analysis. Our study applied a previously established method to induce MC3T3-E1 cell differentiation into osteoblasts and osteoblast precursors. Our results showed that the expression of Notch receptors (Notch1-4), ligands (Jagged1, Jagged2 and Delta1), target of Notch signaling (Hes1) and markers (ALP, M-CSF, RANKL and OPG) were altered following 2 and 4Gy of irradiation. The present research did not indicate a strong relationship between Notch1 regulation and suppression of osteoblast differentiation. We found Hes1 may play a role in the radiation effect on osteoblast differentiation. Our results indicate that radiated osteoblast precursors and osteoblasts promoted osteoclast differentiation and proliferation.

Updates in Hemoglobinopathies

I am honored to invite you to enjoy reading this special issue of The Scientific World Journal. One review article is “Ineffective erythropoiesis in β-thalassemia.” The authors concluded that this ineffective erythropoiesis could be the conjunction of several mechanisms of which the final consequence is the arrest of maturation and increased apoptosis of erythroblasts during their terminal differentiation stage. Another review article discusses the biologic complexity in sickle cell disease. This complexity is likely to be one of the major barriers to the development of successful new treatments which, to date, has largely concentrated on individual mechanistic pathways. Future development of therapeutics needs to continue. Another review article titled “Phytomedicines and nutraceuticals: alternative therapeutics for sickle cell anemia” highlights the feasibility of botanicals, mainly antisickling phytomedicines and nutraceuticals, as attractive potential candidates for sickle cell anemia therapy and strongly collaborates the ethnomedical usage of the plants. A peer-reviewed original article was carefully selected from many articles submitted to the journal. It studied the impact of migrations on the health services for hemoglobin disorders in Europe. Its results show that countries with traditional strong prevention and treatment programs are well prepared to face these challenges, while others are urgently needed to address these problems in a systematic way. More articles will be published in this special issue. On behalf of the guest editors of this special issue of The Scientific World Journal, I look forward to receiving your comments and any suggestions you may have. Youssef Al-Tonbary Fernando Tricta Amal El-Beshlawy Mohamed Ahmed Badr Ahmed Mansour

Signatures of Human NK Cell Development and Terminal Differentiation

Natural killer (NK) cells are part of the innate lymphoid cell (ILC) family and represent the main cytotoxic population. NK cells develop from bone marrow common lymphoid progenitors and undergo terminal differentiation in the periphery, where they finally gain their cytotoxic competence as well as the ability to produce IFN-γ in response to engagement of activating receptors. This process has been at least partially elucidated and several markers have been identified to discriminate different NK cell stages and other ILC populations. NK cell terminal differentiation is not only associated with progressive phenotypic changes but also with defined effector signatures. In this essay, we will describe the phenotypic and functional characteristics of the main stages of NK cell development and terminal differentiation and discuss them in light of recent discoveries of novel ILC populations.

Association between Arsenic Suppression of Adipogenesis and Induction of CHOP10 via the Endoplasmic Reticulum Stress Response

Background: There is growing evidence that chronic exposure to inorganic arsenic (iAs) is associated with an increased prevalence of type 2 diabetes (T2D). However, the mechanisms for the diabetogenic effect of iAs are still largely unknown. White adipose tissue (WAT) actively stores and releases energy and maintains lipid and glucose homeostasis.Objective: We sought to determine the mechanisms of arsenic suppression of adipogenesis.Methods: The effects and associated mechanisms of iAs and its major metabolites on adipogenesis were determined in 3T3-L1 preadipocytes, mouse adipose-derived stromal-vascular fraction cells (ADSVFCs), and human adipose tissue–derived stem cells (ADSCs).Results: Exposure of 3T3-L1 preadipocytes to noncytotoxic levels of arsenic, including inorganic arsenite (iAs3+, ≤ 5 μM), inorganic arsenate (≤ 20 μM), trivalent monomethylated arsenic (MMA3+, ≤ 1 μM), and trivalent dimethylated arsenic (DMA3+, ≤ 2 μM) decreased adipogenic hormone-induced adipogenesis in a concentration-dependent manner. In addition, iAs3+, MMA3+, and DMA3+ exhibited a strong inhibitory effect on adipogenesis in primary cultured mouse ADSVFCs and human ADSCs. Time-course studies in 3T3-L1 cells revealed that inhibition of adipogenesis by arsenic occurred in the early stage of terminal adipogenic differentiation and was highly correlated with the induction of C/EBP homologous protein (CHOP10), an endoplasmic reticulum (ER) stress response protein. Induction of CHOP10 by arsenic is associated with reduced DNA-binding activity of CCAAT/enhancer-binding protein β (C/EBPβ), which regulates the transcription of peroxisome proliferator-activated receptor γ and C/EBPα.Conclusions: Low-level iAs and MMA3+ trigger the ER stress response and up-regulate CHOP10, which inhibits C/EBPβ transcriptional activity, thus suppressing adipogenesis. Arsenic-induced dysfunctional adipogenesis may be associated with a reduced capacity of WAT to store lipids and with insulin resistance.