Features of Intracellular Signal Transduction in Neural Stem Cells under the Influence of Alkaloid Songorine, an Agonist of Fibroblast Growth Factor Receptors.

We performed a comparative in vitro study of the involvement of NF-κB, PI3K, cAMP, ERK1/2, p38, JAKs, STAT3, JNK, and p53-dependent intracellular signaling in the functioning of neural stem cells (NSC) under the influence of basic fibroblast growth factor (FGF) and FGF receptor agonist, diterpene alkaloid songorine. The significant differences in FGFR-mediated intracellular signaling in NSC were revealed for these ligands. In both cases, stimulation of progenitor cell proliferation occurs with the participation of NF-κB, PI3K, ERK1/2, JAKs, and STAT3, while JNK and p53, on the contrary, inhibit cell cycle progression. However, under the influence of songorin, cAMP- and p38-mediated cascades are additionally involved in the transmission of the NSC division-activating signal. In addition, unlike FGF, the alkaloid stimulates progenitor cell differentiation by activating ERK1/2, p38, JNK, p53, and STAT3.

The Role of JNK and p53 in the Regulation of Secretory Function of Neuroglial Cells of Various Types in ß-Amyloid-Induced Neurodegeneration.

We studied the effect of JNK and p53 inhibitors on the production of neurotrophic factors stimulating the realization of the growth potential of neural stem cells by neuroglial cells of various types under conditions of simulation of induced ß-amyloid neurodegeneration in vitro. It was shown that ß-amyloid stimulates the production of neurotrophins by astrocytes and microglial cells, but does not affect the functioning of oligodendrocytes. JNK and p53 were not involved in the secretion of neurotrophins by intact astrocytes. The stimulating role of p53 on the implementation of their secretory activity under the influence of a neurotoxic agent was revealed. At the same time, the inhibitory role of JNK and p53 in the production of neurotrophic growth factors by oligodendrocytes and microglial cells was revealed both under conditions of their optimal vital activity and when ß-amyloid was added to the cell culture.

Participation of cAMP-Mediated Signaling Transduction in the Regulation of the Secretory Function of Neuroglia during Ethanol-Induced Neurodegeneration.

We studied the involvement of cAMP and PKA in the regulation of the secretion of neurotrophic growth factors by macro-and microglial cells in the model of ethanol-induced neurodegeneration in vitro and in vivo. The stimulating role of cAMP in the secretion of neurotrophins by intact astrocytes and oligodendrocytes was shown, while PKA does not participate in this process. On the contrary, the inhibitory role of cAMP (implemented via PKA activation) in the production of neurogenesis stimulators by microglial cells under conditions of optimal vital activity was found. Under the influence of ethanol, the role of cAMP and PKA in the production of growth factors by macroglial cells was considerably changed. The involvement of PKA in the cAMP-dependent signaling pathways and inversion of the role of this signaling pathway in the implementation of the neurotrophic secretory function of astrocytes and oligodendrocytes, respectively, directly exposed to ethanol in vitro were noted. Long-term exposure of the nervous tissue to ethanol in vivo led to the loss of the stimulating role of cAMP/PKA signaling on neurotrophin secretion by macroglial cells without affecting its inhibitory role in the regulation of this function in microglial cells.

The Role of Intracellular Signaling Molecules in the Production of Granulocytic CSF Mononuclear Phagocytes in Stress and Cytostatic Influence.

Under conditions of steady-state hemopoiesis, nuclear factor NF-κB, in contrast to MAP kinase p38, plays an important role in the maintenance of the initial level of secretory activity of monocytes. The increase in the production of G-CSF under stress conditions (10-h immobilization) is mainly regulated by the alternative p38MARK signaling pathway via activation of p38 synthesis. It was shown that under conditions of cytostatic-induced myelosuppression, the production of protein kinase p38 in cells decreases, and it, like NF-κB, is not the main one in the production of hemopoietin by mononuclear phagocytes.

Role of JNK and p53 in Implementation of Functions of Various Types of Regeneration-Competent Cells of the Nervous Tissue.

We studied the participation of JNK and p53 in the realization of the growth potential of different types of progenitors of the subventricular zone of mouse brain and secretion of neurotrophins by glial cells. The stimulating role of these signaling molecules in mitotic activity and specialization of multipotent neural stem cells was shown. It was found that JNK and p53 do not participate in the regulation of committed neuronal progenitor cells (clonogenic PSA-NCAM+ cells). A dependence of neurotrophic growth factors in individual populations of neuroglia on activity of these protein kinase and transcription factor was revealed. The role of JNK and p53 in astrocytes consists in stimulation of their secretion, and in microglial cells, on the contrary, in its inhibition. The secretory neurotrophic function of oligodendrogliocytes is not associated with JNK and p53 activity.

Involvement of Signaling Cascades in Granulocytopoiesis Regulation under Conditions of Cytostatic Treatment.

Suppression of the production of granulocytic CSF under the effect of 5-fluorouracyl is related to disorders in the NF-κB-, cAMP-dependent signaling pathways and MAPK cascade. These secondary messengers are involved in the regulation of functional activity of nonadherent myelokaryocytes starting from day 10 of the experiment (initial period of the hemopoietic granulocytic stem regeneration after antimetabolite challenge). Granulocytic CSF does not play essential role in the formation of colony-stimulating activity of cells of the adherent and nonadherent fractions of the bone marrow. Only cAMP-dependent pathway is involved in the regulation of the realization of the granulocytic precursor growth potential in response to the challenge.

Peculiarities of the Involvement of MAPKS ERK1/2 and р38 in the Implementation of the Functions of Neural Stem Cells and Neuronal Committed Precursors in Ethanol-Induced Neurodegeneration.

We studied the peculiarities of the participation of ERK1/2 and р38 in regulation of various types of progenitor cells of the nervous tissue under conditions of ethanol-induced neurodegeneration modeled in vitro and in vivo. The stimulating role of these signaling molecules in the realization of the growth potential of intact multipotent neural stem cells and committed neuronal precursors (clonogenic PSA-NCAM+ cells) was demonstrated. In vitro exposure to neurotoxic doses of ethanol led to the loss of the specified role of ERK1/2 and p38 in the cell cycle regulation. Inversion of the role of both studied MAP-kinases in determining the proliferation status of neural stem cells after long-term administration of ethanol to experimental animals was revealed. In committed neuronal precursors, this inversion (inhibition of mitotic activity instead of activation) was revealed only for ERK1/2. In mice exposed to chronic alcoholization, ERK1/2 no longer participated in the process of specialization of both types of regeneration-competent cells of the nerve tissue. The revealed fundamental difference between the functions of ERK1/2 and p38 in the cell cycle regulation in neural stem cells and committed neuronal precursors under optimal conditions and during ethanol-induced neurodegeneration does not allow drawing definite conclusions about the prospect of using modifiers of their activity for the therapy for alcohol-related CNS pathologies.

Hemostimulating Effects of c-Jun N-Terminal Kinase (JNK) Inhibitor during Cytostatic Myelosuppression and Mechanisms of Their Development.

The hemostimulating effects of c-Jun N-terminal kinase (JNK) inhibitor were examined on the mouse model of myelosuppression provoked by 5-fluorouracil. Blockade of JNK during postcytostatic period accelerated recovery of granulomonocytopoiesis and erythropoiesis. It also increased the content of neutrophilic granulocytes and erythroid cells in the hematopoietic tissue and elevated the counts of neutrophils and reticulocytes in the peripheral blood. The development of these phenomena resulted from elevated content and up-regulated functional activity of bone marrow hematopoietic progenitors associated with the direct action of JNK inhibitor on these progenitors and enhanced secretion of hemopoietins by stromal elements of the hematopoiesis-inducing microenvironment.

Specific Roles of JAKs and STAT3 in Functions of Neural Stem Cells and Committed Neuronal Progenitors during Ethanol-Induced Neurodegeneration.

Peculiar roles of JAKs and STAT3 in realization of growth potential of various types of progenitor cells in neural tissue were examined during ethanol-induced neurodegeneration modeled both in vitro and in vivo. During in vitro action of C2H5OH, these signal molecules exerted the opposite effects on mitotic activity of multipotent neural stem cells and committed neural progenitors (the clonogenic PSA-NCAM+ cells). The JAKs and STAT3 inhibitors down-regulated the rate of neural stem cell division (proliferative activity) but up-regulated such activity of the committed neural progenitors. A long-term in vivo exposure of mice to ethanol inversed the roles of JAKs and STAT3 in determination of proliferative status of neural stem cells and eliminated involvement of JAKs in functional control over the committed progenitors of neurons. The data attest to much promise of STAT3 inhibitors in treatment of ethanol-induced CNS diseases as the remedies that stimulate realization of growth potential in multipotent neural stem cells and committed neural progenitors.

Participation of cAMP/PKA-Mediated Signaling Pathways in Functional Activity of Regeneration-Competent Cells in the Nervous Tissue under Conditions of Ethanol-Induced Neurodegeneration.

We studied the involvement of cAMP/PKA signaling in the realization of the growth potential of neural progenitors and secretion of neurotrophic growth factors by glial elements under conditions of ethanol-induced neurodegeneration in vitro and in vivo. The stimulating role of cAMP and PKA in cell cycle progression of the neural progenitor cells and in production of neurotrophins by the cells in nervous tissue under the optimal conditions to vital activity was demonstrated. Ethanol inverted the role of cAMP/PKA signaling pathways in determination of the proliferation-differentiation status of neural stem cells. Selective blockade of adenylate cyclase or PKA in neural stem cells increased the rate of their division against the background of relative decrease in differentiation rate. In addition, cAMP/PKA signaling does not longer participate in neurotrophin production by glial cells in neurodegeneration. These findings suggest that inhibitors of activity/expression of adenylate cyclase and PKA can be considered as possible drugs with regenerative activity for the treatment of nervous system pathologies provoked by alcohol.

Peculiarities of Intracellular Signal Transduction in the Regulation of Functions of Mesenchymal, Neural, and Hematopoietic Progenitor Cells.

The role of NF-κB, cAMP/PKA, JAKs/STAT3, ERK1/2, p38, JNK, and p53 signaling pathways in the realization of growth potential of mesenchymal, neural, erythroid, and granulomonocytic progenitor cells were examined in vitro. Using selective blockers of signaling molecules, we revealed some principal distinctions of their involvement in determination of proliferation-differentiation status of the progenitor cells of different functional classes. The most salient peculiarities were observed in the roles of cAMP/PKA, JNK, and JAKs/STAT3 signaling pathways in the control of functions of various types of the regeneration-competent elements. The specific features of intracellular signaling revealed in histogenetically and functionally different progenitor cells attest to visibility of differentiated pharmacological stimulation of regeneration in individual tissues and prospectiveness in the development of targeted remedies for regenerative medicine based on modifiers of activity of the intracellular signaling molecules.

Role of Signaling Molecules in the Regulation of Granulocytopoiesis during Stress-Inducing Stimulation.

The role of signaling molecules in synthesis of humoral regulators of granulocytopoiesis by the hematopoietic microenvironmental cells during stress was analyzed using specific inhibitors. The major role in stimulation of the synthesis of granulocytic CSF during stressful stimulation is played by PI3K/Akt signaling cascade. Nuclear transcription factor NF-κB plays an auxiliary role in the regulation of functional activity of the bone marrow mononuclears. However, this factor affects the synthesis of granulocytic CSF by CD4+ cells of the bone marrow in response to stressful stimulation. Different degree and specific character of involvement of the signaling proteins in the regulation of the production of humoral factors determining colony-stimulating activity are explained by changes in functional state of monocyte-derived macrophages in different periods of stress response.

Mechanisms of Granulocytopoiesis Recovery Stimulation with Filgrastim in Breast Cancer Patients Receiving Chemotherapy.

We studied myelotoxicity of modern schemes of chemotherapy for breast cancer (docetaxel/doxorubicin and cyclophosphamide/doxorubicin/5-fluorouracil) towards granulocytopoiesis, the mechanisms determining the differences of hematological effects of these schemes, and the efficiency of correction of the observed changes with granulocyte CSF (filgrastim). Granulocytopoiesis stimulation with filgrastim during the treatment with docetaxel/doxorubicin combination was more pronounced than during cyclophosphamide/doxorubicin/5-fluorouracil therapy. The observed differences were found at all levels of granulocyte lineage organization (central and peripheral), which is related to different effects of the cytostatic substances used in the proposed protocols on the structures controlling hemopoiesis.

Role of JAK/STAT3 Signaling in Functional Stimulation of Mesenchymal Progenitor Cells with Alkaloid Songorine.

JAK/STAT signaling pathway was examined comparatively during realization of growth potential of mesenchymal progenitor cells stimulated with diterpene alkaloid songorine or fibroblast growth factor. The stimulating role of JAKs and STAT3 on the mitotic activity and differentiation of progenitor cells cultured with songorine was revealed. Under these conditions, the study demonstrated suppression of fibroblast colony formation against the background of reduced number of actively proliferating CFU-fibroblasts and a drop of differentiation index of progenitor cells induced by pan-JAKs and STAT3 inhibitors. The observed changes were in almost complete agreement with the character of functional reactions of the progenitor elements in response to blockade of JAKs and STAT3 with fibroblast growth factor. In addition, blockade of JAKs with this factor enhanced the differentiation rate of the progenitor cells.

Role of JAK/STAT3 Signaling in Functional Stimulation of Mesenchymal Progenitor Cells by Fibroblast Growth Factor.

JAK/STAT signaling pathway was examined during functional stimulation of mesenchymal progenitor cells with fibroblast growth factor. The differences were observed in the realizations of the proliferation-differentiation potential of CFU-fibroblasts under blockade of JAKs or during selective inactivation of STAT3. The study revealed stimulating influences of JAKs and STAT3 on mitotic activity of progenitor cells and individual roles of these proteins in the control of their maturation. Blockade of JAKs diminished the level of fibroblast colony formation and the score of actively proliferating CFU-fibroblasts at the background increase of the differentiation rate of progenitor cells. In contrast, STAT3 inhibitor resulted in a coordinated decrease of all examined parameters.

Particular Role of JAK/STAT3 Signaling in Functional Control of Mesenchymal Progenitor Cells.

The role of JAK/STAT3-mediated signaling pathway in the realization of the growth potential of mesenchymal precursor cells was examined in vitro. The stimulating role of JAKs and STAT3 towards proliferating activity of progenitor cells and their different role in the regulation of differentiation of the progenitor elements were demonstrated. Inhibitors of JAKs and STAT3 reduced the yield of fibroblast CFU and their mitotic activity. Blockade of JAKs accelerated and selective inactivation of STAT3 decelerated differentiation of progenitor cells.

Assessment of Erythroid and Granulocytic Hematopoietic Lineages in Patients with Non-Small-Cell Lung Carcinoma.

The toxic effects of combined cisplatin/docetaxel therapy cycles on erythroid and granulocytic hematopoietic lineages as well as their intercycle recovery were examined in patients with stage III-IV non-small-cell lung carcinoma. Responsiveness of the blood system to this therapy remained at a high level. Combined therapy pronouncedly activated the key elements of the erythroid and granulocytic hematopoietic lineages leading to accumulation of immature and mature myelokaryocytes in the bone marrow, enlargement of the medullary pool of mature neutrophils, and increase in the count of medullary erythroid and granulocytic precursor cells under conditions of their accelerated maturation.

Role of JAK1, JAK2, and JAK3 in Functional Stimulation of Mesenchymal Precursor Cells by Alkaloid Songorine.

We studied the role of some JAK in the effect of diterpene alkaloid songorine on realization of the growth potential of mesenchymal precursor cells. The participation of JAK1, JAK2, and JAK3 in stimulation of proliferation of the precursor cells was demonstrated. Specific inhibitors of these JAK reduced the yield of fibroblast CFU and the rate of their division. Inhibition of JAK2 against the background of songorine treatment increased the rate of precursor differentiation.

Role of NF-κB, PI3K, MAPK/ERK 1/2, and p38 in Erythropoietin Production by Bone Marrow Nuclears under Conditions of Immobilization Stress.

The involvement of the studied signal cascades in the regulation of erythropoietin production by bone marrow nuclears under conditions of immobilization stress depends on the type of the hemopoiesis-inducing microenvironment cells and the period of blood system reaction to stress exposure. Secretory activity of monocytes is regulated mainly by PI3K improving cell resistance to disturbances. The functional role of signal cascades involved in the production of erythropoietin by T cells is determined by the stage of the common adaptation syndrome.

Involvement of JAK1, JAK2, and JAK3 in Stimulation of Functional Activity of Mesenchymal Progenitor Cells by Fibroblast Growth Factor.

We studied the involvement of individual JAK kinases in the realization of the growth potential of mesenchymal precursors under the effect of fibroblast growth factor. The important role of JAK2 and JAK3 in determining the initial level of mitotic activity of progenitor cells and participation of JAK1 in this process under conditions of cytokine stimulation of progenitor cells were demonstrated. Specific inhibitors of these kinases reduced the yield of fibroblast CFU and the rate of their division. Moreover, blockade of JAK1, JAK2, and JAK3 under the effect of fibroblast growth factor was accompanied by an increase in the intensity of progenitor cell differentiation.