The presence of ANP in rat peritoneal mast cells

Atrial natriuretic peptide （ANP） is an important component of the natriuretic peptide system. A great role in many regulatory systems is played by mast cells. Meanwhile involvement of these cells in ANP activity is poorly studied. In this work, we have shown the presence of ANP in rat peritoneal mast cells. Pure fraction of mast cells was obtained by separation of rat peritoneal cells on a Percoll density gradient. By Westem blotting, two ANP-immunoreactive proteins of molecular masses of 2.5 kDa and 16.9 kDa were detected in lysates from these mast cells. Electron microscope immunogold labeling has revealed the presence of ANP-immunoreactive material in storage, secreting and released granules of mast cells. Our findings indicate the rat peritoneal mast cells to contain both ANP prohormone and ANP. These both peptides are located in mast cell secretory granules and released by mechanism of degranulation. It is discussed that many mast cell functions might be due to production of natriuretic peptides by these cells.

Stimulation of decidua development by transplantation of endometrial stem cells

On all terms of pregnancy, insolvency of decidual reaction of endometrial cells is one of the reasons of miscarriages and fetal growth delay. The insufficient decidualization of endometrum leads to infertility in such pathologies, as Asherman’s syndrome and an endometrium atrophy. However, there are data on successful application of autologous bone marrow MSCs for Asherman’s syndrome treatment. The aim of this work was to assay the effect of endometrial mesenchymal stem cell (eMSC) transplantation for decidualization process in pseudopregnant rat. Our study showed that injection of human eMSC suspension into the uterine lumen of pseudopregnant rats facilitated more intensive development of decidua in comparison with phosphate buffed saline (PBS) injection in the control uterine horn. Histological analysis of decidua sections did not reveal any alterations in cell differentiation or tissue structure. In conclusion, we demonstrated for the first time that eMSC transplantation assists the development of all decidual tissue elements. It opens the possibility that eMSCs may be applied for cell therapy of infertility associated with decidualzation insufficiency.

Association of Glial Activation and α-Synuclein Pathology in Parkinson's Disease

The accumulation of pathological α-synuclein(α-syn)in the central nervous system and the progressive loss of dopaminergic neurons in the substantia nigra pars compacta are the neuropathological features of Parkinson's disease(PD).Recently,the findings of prion-like transmission of α-syn pathology have expanded our understanding of the region-specific distribution ofα-syn in PD patients.Accumulating evidence suggests that α-syn aggregates are released from neurons and endocytosed by glial cells,which contributes to the clearance of α-syn.However,the activation of glial cells by α-syn species produces pro-inflammatory factors that decrease the uptake of α-syn aggregates by glial cells and promote the transmission of α-syn between neurons,which promotes the spread of α-syn pathology.In this article,we provide an overview of current knowledge on the role of glia and α-syn pathology in PD pathogenesis,highlighting the relationships between glial responses and the spread ofα-syn pathology.

Transient expression of inactive RB in mesenchymal stem cells impairs their adipogenic potential and is associated with hypermethylation of the PPARγ2 promoter

The retinoblastoma gene product(pRb)is a chromatin-associated protein that can either suppress or promote activity of key regulators of tissue-specific differentiation.We found that twelve weeks after transfection of the exogenous active(ΔB/X andΔр34)or inactive(ΔS/N)forms of RB into the 10T1/2 mesenchymal stem cells and clonal selection not a single cell line did contain exogenous RB,despite being G-418 resistant.However,the consequences of the transient production of exogenous RB had different effects on the cell fate.TheΔB/X andΔр34 cells transfected with active form of RB showed elevated levels of inducible adipocyte differentiation(AD).On the contrary,theΔS/N cells transfected with inactive RB mutant were insensitive to induction of AD associated with abolishing of expression of the PPARγ2.Additionally,the PPARγ2 promoter in undifferentiatedΔS/N cells was hypermethylated,but all except−60 position CpG became mostly demethylated after cells exposure to AD.We conclude that while transient expression of inactive exogenous RB induces long term epigenetic alterations that prevent adipogenesis,production of active exogenous RBs results in an AD-promoting epigenetic state.These results indicate that pRb is involved in the establishment of hereditary epigenetic memory at least by creating a methylation pattern of PPARγ2.

pRb-E2F signaling in life of mesenchymal stem cells:Cell cycle,cell fate,and cell differentiation

Mesenchymal stem cells(MSCs)are multipotent cells that can differentiate into various mesodermal lines forming fat,muscle,bone,and other lineages of connective tissue.MSCs possess plasticity and under special metabolic conditions may transform into cells of unusual phenotypes originating from ecto-and endoderm.After transplantation,MSCs release the humoral factors promoting regeneration of the damaged tissue.During last five years,the numbers of registered clinical trials of MSCs have increased about 10 folds.This gives evidence that MSCs present a new promising resource for cell therapy of the most dangerous diseases.The efficacy of the MSCs therapy is limited by low possibilities to regulate their conversion into cells of damaged tissues that is implemented by the pRb-E2F signaling.The widely accepted viewpoint addresses pRb as ubiquitous regulator of cell cycle and tumor suppressor.However,current publications suggest that basic function of the pRb-E2F signaling in development is to regulate cell fate and differentiation.Through facultative and constitutive chromatin modifications,pRb-E2F signaling promotes transient and stable cells quiescence,cell fate choice to differentiate,to senesce,or to die.Loss of pRb is associated with cancer cell fate.pRb regulates cell fate by retaining quiescence of one cell population in favor of commitment of another or by suppression of genes of different cell phenotype.pRb is the founder member of the“pocket protein”family possessing functional redundancy.Critical increase in the efficacy of the MSCs based cell therapy will depend on precise understanding of various aspects of the pRb-E2F signaling.

Magnesium permeation through mechanosensitive channels:single-current measurements

Compelling evidence shows that intracellular free magnesium [Mg^2＋]i may be a critical regulator of cell activity in eukaryotes. However, membrane transport mechanisms mediating Mg^2＋ influx in mammalian cells are poorly understood. Here, we show that mechanosensitive （MS） cationic channels activated by stretch are permeable for Mg^2＋ ions at different extracellular concentrations including physiological ones. Single-channel currents were recorded from cell-attached and inside-out patches on K562 leukaemia cells at various concentrations of MgCl2 when Mg^2＋ was the only available carrier of inward currents. At 2 mM Mg^2＋, inward mechanogated currents representing Mg^2＋ influx through MS channels corresponded to the unitary conductance of about 5 pS. At higher Mg^2＋ levels, only slight increase of single-channel currents and conductance occurred, implying that Mg^2＋ permeation through MS channels is characterized by strong saturation. At 20 and 90 mM Mg^2＋, mean conductance values for inward currents carried by Mg^2＋ were rather similar, being equal to 6.8 ± 0.5 and 6.4 ± 0.5 pS, respectively. The estimation of the channel-selective permeability according to constant field equation is obviously limited due to saturation effects. We conclude that the detection of single currents is the main evidence for Mg^2＋ permeation through membrane channels activated by stretch. Our single-current measurements document Mg^2＋ influx through MS channels in the plasma membrane of leukaemia cells.

The RhoA nuclear localization changes in replicative senescence:New evidence from in vitro human mesenchymal stem cells studies

All non-immortalized mesenchymal stem cells have a limited proliferative potential,that is,replicative senescence(RS)is an integral characteristic of the life of all mesenchymal stem cells(MSCs).It is known that one of the important signs of RS is a decrease of cell motility,and that violations of migration processes contribute to the deterioration of tissue regeneration.Therefore,the characterization of the properties of the cell line associated with RS is a prerequisite for the effective use of MSCs in restorative medicine.One of the key proteins regulating cell motility is the small GTPase RhoA.The main purpose of this work was to study the nuclear-cytoplasmic redistribution of the RhoA protein during RS in MSC lines recently obtained and characterized in our laboratory.The study found that a comparative analysis of the intracellular localization of RhoA in three cell lines(MSCWJ-1,FetMSC,DF2)showed a decrease in the nuclear localization of RhoA during RS.

Genome variation in the trophoblast cell lifespan: Diploidy, polyteny, depolytenization, genome segregation

The lifespan of mammalian trophoblast cells includes polyploidization, its degree and peculiarities are, probably, accounted for the characteristics of placenta development. The main ways of genome multiplication-endoreduplication and reduced mitosis-that basically differ by the extent of repression of mitotic events, play, most probably, different roles in the functionally different trophoblast cells in a variety of mammalian species. In the rodent placenta, highly polyploid(512-2048c) trophoblast giant cells(TGC) undergoing endoreduplication serve a barrier with semiallogenic maternal tissues whereas series of reduced mitoses allow to accumulate a great number of low-ploid junctional zone and labyrinth trophoblast cells. Endoreduplication of TGC comes to the end with formation of numerous low-ploid subcellular compartments that show some signs of viable cells though mitotically inactive; it makes impossible their ectopic proliferation inside maternal tissues. In distinct from rodent trophoblast, deviation from(2n)c in human and silver fox trophoblast suggests a possibility of aneuploidy and other chromosome changes(aberrations, etc.). It suggests that in mammalian species with lengthy period of pregnancy, polyploidy is accompanied by more diverse genome changes that may be useful to select a more specific response to stressful factors that may appear occasionally during months of intrauterine development.

Stromal and Tumor Glioma-derived Cells with Similar Characteristics Have Differences in α-Smooth Muscle Actin Expression and Localization

Gliomas are solid brain tumors composed of tumor cells and recruited heterogenic stromal components.The study of the interactions between the perivascular niche and its surrounding cells is of great value in unraveling mechanisms of drug resistance in malignant gliomas.In this study,we isolated the stromal diploid cell population from oligodendroglioma and a mixed population of tumor aneuploid and stromal diploid cells from astrocytoma specimens.The stromal cells expressed neural stem/progenitor and mesenchymal markers showing the same discordant phenotype that is typical for glioma cells.Moreover,some of the stromal cells expressed CD133.For the first time,we demonstrated that this type of stromal cells had the typical myofibroblastic phenotype as theα-SMA+cells formedα-SMA fibers and exhibited the specific function to deposit extracellular matrix(ECM)proteins at least in vitro.Immunofluorescent analysis showed diffuse or focalα-SMA staining in the cytoplasm of the astrocytoma-derived,A172,T98G,and U251MG glioma cells.We could suggest thatα-SMA may be one of the main molecules,bearing protective functions.Possible mechanisms and consequences ofα-SMA disruptions in gliomas are discussed.

Legumain-triggered aggregable gold nanoparticles for enhanced intratumoral retention

Insufficient intratumoral retention of nanomedicines remains the major challenge for broad implementation in clinical sets.Herein,we proposed a legumain-triggered aggregable gold nanoparticle(GNP)delivery platform(GNPs-A&C).GNPs-A&C could form intratumoral or intracellular aggregates in response to the overexpressed legumain.The aggregates with size increase not only could reduce back-flow from interstitial space to peripheral bloodstream but also could restrict the cellular exocytosis,leading to enhanced intratumoral retention.In vitro studies demonstrated that GNPs-A&C possessed an excellent legumain responsiveness and the increased size was closely relevant with legumain expression.In vivo studies demonstrated GNPs-A&C possessed slower clearance rate and much higher intratumoral retention within legumain-overexpressed tumor compared to non-aggregable NPs,regardless of intravenous or intratumoral injection.More importantly,this delivery platform significantly improved the chemotherapeutic effect of doxorubicin(DOX)towards subcutaneous xenograft C6 tumor.The effectiveness of this stimulus-responsive aggregable delivery system provides a thinking for designing more intelligent size-tunable nanomedicine that can substantially improve intratumoral retention.