hUC-MSCs secreted exosomes inhibit the glioma cell progression through PTENP1/miR-10a-5p/PTEN pathway.

OBJECTIVE: The mesenchymal stem cells (MSCs) have been widely studied for their anti-tumor property, due to the characteristic of homing towards tumor sites and immunosuppression. Nevertheless, the underlying molecular mechanisms that link MSCs to the targeted tumor cells, such as glioma, are not clear. MATERIALS AND METHODS: Here, we examined the inhibitory properties and new molecular mechanisms of the human umbilical cord (hUC-MSCs) derived exosomes on the human glioma U87 cells using a co-culture system in vitro. The cell counting kit-8 (CCK-8) assay was performed to measure the anti-tumor activity of hUC-MSCs derived exosomes. The cell apoptosis was assessed by flow cytometry and the immunoblotting assay was applied in order to assess the associated proteins level. The data revealed that hUC-MSCs derived exosomes could repress cell proliferation and induce cell apoptosis. RESULTS: Mechanistically, we identified that lncRNA PTENP1 could be packaged into exosome from hUC-MSCs, transferred to U87 cells, and then stabilized PTEN by binding miR-10a-5p competitively. CONCLUSIONS: Therefore, our data suggested that the exosomes from hUC-MSCs possess a higher anti-tumor capacity, at least partially, via regulating miR-10a-5p/PTEN signaling, which thereby may represent a possible target for early diagnosis and treatment of glioma clinically.

Erythropoietin Receptor Activation Protects the Kidney From Ischemia/Reperfusion-Induced Apoptosis by Activating ERK/p53 Signal Pathway.

BACKGROUND: Apoptosis plays an important role in renal ischemia/reperfusion (IR) injury. Evidence has shown that erythropoietin (EPO) has an antiapoptotic effect. Therefore, this study aimed to explore the effect and potential mechanism of EPO in renal IR injury. METHODS: Kidney IR injury in rats was established by clamping the left renal artery for 30 minutes followed by 24 hours of reperfusion, along with contralateral nephrectomy. Renal function, renal histology, and expression of EPOR, p-EPOR, ERK, p-ERK, p-p53, p53, Bcl-2, Bcl-xl, Bad, and Bax were examined. RESULTS: Pretreatment with EPO significantly reduced renal dysfunction, pathologic change, and expression of Bad and Bax. Furthermore, EPO treatment enhanced the expression of p-ERK, p-p53, Bcl-2, and Bcl-xl with no influence on the expression of EPOR, ERK, and p53. CONCLUSIONS: These findings demonstrated that EPO pretreatment can attenuate renal IR injury by inhibiting apoptosis by promoting activation of the ERK/p53 signaling.

Epigenetic silencing of CD4 in T cells committed to the cytotoxic lineage.

The process of thymocyte development culminates in the maturation of helper (CD4+) and cytotoxic (CD8+) T cells from their common precursors, the CD4+CD8+ double-positive cells. A crucial step during lineage specification is the termination of expression of either the CD4 or the CD8 coreceptor. A silencer element within the first intron of the CD4 gene is sufficient for CD4 transcriptional repression in cells of the cytotoxic lineage, as well as in thymocytes at earlier stages of differentiation. Here we show that the function of the CD4 silencer is required only at distinct stages of development. Its deletion before the initiation of lineage specification resulted in CD4 derepression throughout thymocyte differentiation. By contrast, once cells committed to the cytotoxic CD8+ lineage, the CD4 locus remained silent through subsequent mitoses, even when the silencer element was excised. The epigenetic inheritance of the silenced CD4 locus was not affected by the inhibition of DNA methylation or histone deacetylation, and may thus involve other mechanisms that ensure a stable state of gene expression.

A coordinated change in chemokine responsiveness guides plasma cell movements.

Antibody-secreting plasma cells are nonrecirculatory and lodge in splenic red pulp, lymph node medullary cords, and bone marrow. The factors that regulate plasma cell localization are poorly defined. Here we demonstrate that, compared with their B cell precursors, plasma cells exhibit increased chemotactic sensitivity to the CXCR4 ligand CXCL12. At the same time, they downregulate CXCR5 and CCR7 and have reduced responsiveness to the B and T zone chemokines CXCL13, CCL19, and CCL21. We demonstrate that CXCL12 is expressed within splenic red pulp and lymph node medullary cords as well as in bone marrow. In chimeric mice reconstituted with CXCR4-deficient fetal liver cells, plasma cells are mislocalized in the spleen, found in elevated numbers in blood, and fail to accumulate normally in the bone marrow. Our findings indicate that as B cells differentiate into plasma cells they undergo a coordinated change in chemokine responsiveness that regulates their movements in secondary lymphoid organs and promotes lodgment within the bone marrow.

Requirement for RORgamma in thymocyte survival and lymphoid organ development.

Most developing thymocytes undergo apoptosis because they cannot interact productively with molecules encoded by the major histocompatibility complex. Here, we show that mice lacking the orphan nuclear hormone receptor RORgamma lose thymic expression of the anti-apoptotic factor Bcl-xL. RORgamma thus regulates the survival of CD4+8+ thymocytes and may control the temporal window during which thymocytes can undergo positive selection. RORgamma was also required for development of lymph nodes and Peyer's patches, but not splenic follicles. In its absence, there was loss of a population of CD3-CD4+CD45+ cells that normally express RORgamma and that are likely early progenitors of lymphoid organs. Hence, RORgamma has critical functions in T cell repertoire selection and lymphoid organogenesis.

Independent control of immunoglobulin switch recombination at individual switch regions evidenced through Cre-loxP-mediated gene targeting.

We have employed a method based on the Cre-loxP recombination system of bacteriophage P1 to generate a mouse strain in which the JH segments and the intron enhancer in the IgH locus are deleted. By analysis of immunoglobulin isotype switch recombination in heterozygous mutant B cells activated by lipopolysaccharide plus interleukin-4, we show that, on the mutant chromosome, switch recombination at the mu gene switch region is strongly suppressed, whereas the switch region of the gamma 1 gene is efficiently rearranged. These data demonstrate an independent control of switch recombination at individual switch regions and suggest that, in the process of switch recombination, the alignment of the recombining strands occurs independently of and probably after the introduction of double-strand breaks into the switch regions involved.

Gene targeting in the Ig kappa locus: efficient generation of lambda chain-expressing B cells, independent of gene rearrangements in Ig kappa.

The production of lambda chain-expressing B cells was studied in mice in which either the gene encoding the constant region of the kappa chain (C kappa) or the intron enhancer in the Ig kappa locus was inactivated by insertion of a neomycin resistance gene. The two mutants have similar phenotypes: in heterozygous mutant mice the fraction of lambda chain-bearing B cells is twice that in the wildtype. Homozygous mutants produce approximately 7 times more lambda-expressing B cells (and about 2.3 times fewer total B cells) in the bone marrow than their normal counterparts, suggesting that B cell progenitors can differentiate into either kappa- or lambda-producing cells and do the latter in the mutants. Whereas gene rearrangements in the Ig kappa locus are blocked in the case of enhancer inactivation, they still occur in that of the C kappa mutant, although in this mutant RS rearrangement is lower than in the wildtype. This indicates that gene rearrangements in the Ig lambda locus can occur in the absence of a putative positive signal resulting from gene rearrangements in Ig kappa, including RS recombination. Complementing these results, we also present data indicating that in normal B cell development kappa chain rearrangement can be preceded by lambda chain rearrangement and that the frequency of kappa/lambda double producers is small and insufficient to explain the massive production of lambda chain-expressing B cells in the mutants.