Modulation of extracellular signal-related kinase, cyclin D1, glial fibrillary acidic protein, and vimentin expression in estradiol-pretreated astrocyte cultures treated with competence and progression growth factors

Autologous Platelet Lysate Is an Alternative to Fetal Bovine Serum for Canine Adipose-Derived Mesenchymal Stem Cell Culture and Differentiation

The use of fetal bovine serum (FBS) in regenerative medicine raises serious ethical and scientific concerns. We have cultured and differentiated the canine mesenchymal stem cells (cMSCs) in five different media combinations of autologous platelet lysate (A-PL) and FBS; consisting of 0% A-PL and 10% FBS (M-1), 2.5% A-PL and 7.5% FBS (M-2), 5% A-PL and 5% FBS (M-3), 7.5% A-PL and 2.5% FBS (M-4), and 10% A-PL and 0% FBS (M-5). The cMSCs were evaluated for their doubling time, differentiation efficiency, and expression of CD73, CD90, CD105, and PDGFRα. The mRNA expression of NT5E, THY1, ENG, PPARγ, FABP4, FAS, SP7, BGLAP, and SPP1 was also assessed. The results indicated non-significant differences in cellular proliferation/viability; positive expression of surface markers, and PDGFRα with substantial adipo/osteogenic differentiation. The expression of adipogenic (PPARγ, FABP4, FAS), and osteogenic (SP7, BGLAP, SPP1) genes were higher (p < 0.05) in the M5 group. In conclusion, A-PL in cMSCs culture did not negatively affect cellular proliferation and viability but also enhanced their genetic potential for multilineage differentiation. Our results indicate that A-PL can be used as an alternative for FBS to develop potent cMSCs under good manufacturing practice protocol for regenerative medicine.

The DR1‑CSE/H2S system inhibits renal fibrosis by downregulating the ERK1/2 signaling pathway in diabetic mice

Glomerular mesangial cell (MC) proliferation and extracellular matrix deposition are the main pathological changes in diabetic nephropathy. Hydrogen sulfide (H2S) inhibits the proliferation of MCs. Dopamine 1 receptors (DR1) are expressed in MCs and serve important physiological roles. However, it is unclear whether DR1 activation inhibits MC proliferation by increasing endogenous H2S. The present study found that the production of H2S and the expression of DR1 and cystathionine‑γ‑lyase (CSE) were decreased in the renal tissues of diabetic mice and high glucose (HG)‑induced MCs. SKF38393 (a DR1 agonist) increased the production of H2S and the expression of DR1 and CSE and NaHS (an exogenous H2S donor) only increased H2S production and CSE expression but not DR1 expression. HG increased the thickness of the glomerular basement membrane, cell viability and proliferation, the expression of cyclin D1, PCNA, collagen 1 and α‑smooth muscle actin and the activity of phosphorylated ERK1/2 and decreased the expression of P21 and MMP9. SKF38393 and NaHS reversed the effects of HG. PPG (a CSE inhibitor) abolished the beneficial effects of SKF38393. The beneficial effects of SKF38393 were similar to those of PD98059 (an ERK1/2 inhibitor). Taken together, the findings suggested that the DR1‑CSE/H2S pathway activation attenuated diabetic MC proliferation and extracellular matrix deposition by downregulating the ERK1/2 signaling pathway.

Overexpression of RAPGEF3 enhances the therapeutic effect of dezocine in treatment of neuropathic pain

Pain is a significant problem worldwide that affects the quality of life of patients. Dezocine is a non-addictive analgesic drug with kappa-opioid antagonist activity and has been successfully used to alleviate of postoperative pain. In addition, dezocine has an analgesic effect similar to that of morphine, alleviating moderate to severe pain. Rap guanine nucleotide exchange factor 3 (RAPGEF3) is a guanine nucleotide exchange factor for GTPases Rap1 and Rap2, which could enhance the activity of Rap1 to promote cell adhesion and axon regeneration, as well as promote neurite extension by interacting with nerve growth factors. Here, we first observed that overexpression of RAPGEF3 increased cell viability, as shown by a CCK-8 assay, and recovered brain function in rats. The expression of inflammation-related factors at the mRNA level was detected using qPCR, and the concentration of these factors in a cultured cell medium and rat serum samples were decreased as shown by ELISA after RAPGEF3 overexpression. Through western blotting, we further found that pro-inflammatory proteins were decreased, and these effects might be mediated by inhibition of the Ras/p-38 MAPK signaling pathway. Taken together, we speculated that RAPGEF3overexpression enhances the therapeutic effect of dezocine on neuropathic pain by inhibiting the inflammatory response through inhibition of the Ras/p-38 MAPK signaling pathway.

Protein Kinases Signaling in Pancreatic Beta-cells Death and Type 2 Diabetes

Type 2 diabetes (T2D) is a worldwide serious public health problem. Insulin resistance and β-cell failure are the two major components of T2D pathology. In addition to defective endoplasmic reticulum (ER) stress signaling due to glucolipotoxicity, β-cell dysfunction or β-cell death initiates the deleterious vicious cycle observed in T2D. Although the primary cause is still unknown, overnutrition that contributes to the induction of the state of low-grade inflammation, and the activation of various protein kinases-related metabolic pathways are main factors leading to T2D. In this chapter following subjects, which have critical checkpoints regarding β-cell fate and protein kinases pathways are discussed; hyperglycemia-induced β-cell failure, chronic accumulation of unfolded protein in β-cells, the effect of intracellular reactive oxygen species (ROS) signaling to insulin secretion, excessive saturated free fatty acid-induced β-cell apoptosis, mitophagy dysfunction, proinflammatory responses and insulin resistance, and the reprogramming of β-cell for differentiation or dedifferentiation in T2D. There is much debate about selecting proposed therapeutic strategies to maintain or enhance optimal β-cell viability for adequate insulin secretion in T2D. However, in order to achieve an effective solution in the treatment of T2D, more intensive clinical trials are required on newer therapeutic options based on protein kinases signaling pathways.

Platelet-rich plasma enhances the proliferation of human adipose stem cells through multiple signaling pathways

BACKGROUND

Platelet-rich plasma (PRP) is an autologous blood product that contains a high concentration of several growth factors. Platelet-derived growth factor (PDGF)-BB is a potential mitogen for human adipose-derived stem cells (hASCs). PRP stimulates proliferation of hASCs; however, the signaling pathways activated by PRP remain unclear.

METHODS

hASCs were cultured with or without PRP or PDGF-BB, and proliferation was assessed. hASCs were also treated with PRP or PDGF-BB with or without imatinib, which is a PDGF receptor tyrosine kinase inhibitor, or sorafenib, which is a multikinase inhibitor. Inhibition of cell proliferation was examined using anti-PDGF antibody (Abcam, Cambridge, UK), by cell counting. We assessed the effects of inhibitors of various protein kinases such as ERK1/2, JNK, p38, and Akt on the proliferation of hASCs.

RESULTS

The proliferation was remarkably promoted in cells treated with either 1% PRP or 10 ng/ml PDGF-BB, and both imatinib and sorafenib inhibited this proliferation. Anti-PDGF antibody (0.5 and 2 μg/ml) significantly decreased the proliferation of hASCs compared with control. PRP-mediated hASC proliferation was blocked by inhibitors of ERK1/2, Akt, and JNK, but not by an inhibitor of p38.

CONCLUSIONS

PRP promotes hASC proliferation, and PDGF-BB in PRP plays a major role in inducing the proliferation of hASCs. PRP promotes hASC proliferation via ERK1/2, PI3K/Akt, and JNK signaling pathways.

Neurotrophic and Neuroregenerative Effects of GH/IGF1

Introduction. Human neurodegenerative diseases increase progressively with age and present a high social and economic burden. Growth hormone (GH) and insulin-like growth factor-1 (IGF-1) are both growth factors exerting trophic effects on neuronal regeneration in the central nervous system (CNS) and peripheral nervous system (PNS). GH and IGF-1 stimulate protein synthesis in neurons, glia, oligodendrocytes, and Schwann cells, and favor neuronal survival, inhibiting apoptosis. This study aims to evaluate the effect of GH and IGF-1 on neurons, and their possible therapeutic clinical applications on neuron regeneration in human subjects. Methods. In the literature, we searched the clinical trials and followed up studies in humans, which have evaluated the effect of GH/IGF-1 on CNS and PNS. The following keywords have been used: “GH/IGF-1” associated with “neuroregeneration”, “amyotrophic lateral sclerosis”, “Alzheimer disease”, “Parkinson’s disease”, “brain”, and “neuron”. Results. Of the retrieved articles, we found nine articles about the effect of GH in healthy patients who suffered from traumatic brain injury (TBI), and six studies (four using IGF-1 and two GH therapy) in patients with amyotrophic lateral sclerosis (ALS). The administration of GH in patients after TBI showed a significantly positive recovery of brain and mental function. Treatment with GH and IGF-1 therapy in ALS produced contradictory results. Conclusions. Although strong findings have shown the positive effects of GH/IGF-1 administration on neuroregeneration in animal models, a very limited number of clinical studies have been conducted in humans. GH/IGF-1 therapy had different effects in patients with TBI, evidencing a high recovery of neurons and clinical outcome, while in ALS patients, the results are contradictory. More complex clinical protocols are necessary to evaluate the effect of GH/IGF-1 efficacy in neurodegenerative diseases. It seems evident that GH and IGF-1 therapy favors the optimal recovery of neurons when a consistent residual activity is still present. Furthermore, the effect of GH/IGF-1 could be mediated by, or be overlapped with that of other hormones, such as estradiol and testosterone.

Neurotrophin Promotes Neurite Outgrowth by Inhibiting Rif GTPase Activation Downstream of MAPKs and PI3K Signaling

Members of the well-known semaphorin family of proteins can induce both repulsive and attractive signaling in neural network formation and their cytoskeletal effects are mediated in part by small guanosine 5'-triphosphatase (GTPases). The aim of this study was to investigate the cellular role of Rif GTPase in the neurotrophin-induced neurite outgrowth. By using PC12 cells which are known to cease dividing and begin to show neurite outgrowth responding to nerve growth factor (NGF), we found that semaphorin 6A was as effective as nerve growth factor at stimulating neurite outgrowth in PC12 cells, and that its neurotrophic effect was transmitted through signaling by mitogen-activated protein kinases (MAPKs) and phosphatidylinositol-3-kinase (PI3K). We further found that neurotrophin-induced neurite formation in PC12 cells could be partially mediated by inhibition of Rif GTPase activity downstream of MAPKs and PI3K signaling. In conclusion, we newly identified Rif as a regulator of the cytoskeletal rearrangement mediated by semaphorins.

Effect of glycosides of Cistanche on the expression of mitochondrial precursor protein and keratin type II cytoskeletal 6A in a rat model of vascular dementia

Glycosides of Cistanche (GC) is a preparation used extensively for its neuroprotective effect against neurological diseases, but its mechanisms of action remains incompletely understood. Here, we established a bilateral common carotid artery occlusion model of vascular dementia in rats and injected the model rats with a suspension of GC (10 mg/kg/day, intraperitoneally) for 14 consecutive days. Immunohistochemistry showed that GC significantly reduced p-tau and amyloid beta (Aβ) immunoreactivity in the hippocampus of the model rats. Proteomic analysis demonstrated upregulation of mitochondrial precursor protein and downregulation of keratin type II cytoskeletal 6A after GC treatment compared with model rats that had received saline. Western blot assay confirmed these findings. Our results suggest that the neuroprotective effect of GC in vascular dementia occurs via the promotion of neuronal cytoskeleton regeneration.

Effects of Nerve Growth Factor and Basic Fibroblast Growth Factor Promote Human Dental Pulp Stem Cells to Neural Differentiation

Dental pulp stem cells (DPSCs) were the most widely used seed cells in the field of neural regeneration and bone tissue engineering, due to their easily isolation, lack of ethical controversy, low immunogenicity and low rates of transplantation rejection. The purpose of this study was to investigate the role of basic fibroblast growth factor (bFGF) and nerve growth factor (NGF) on neural differentiation of DPSCs in vitro. DPSCs were cultured in neural differentiation medium containing NGF and bFGF alone or combination for 7 days. Then neural genes and protein markers were analyzed using western blot and RT-PCR. Our study revealed that bFGF and NGF increased neural differentiation of DPSCs synergistically, compared with bFGF and NGF alone. The levels of Nestin, MAP-2, βIII-tubulin and GFAP were the most highest in the DPSCs + bFGF + NGF group. Our results suggested that bFGF and NGF signifiantly up-regulated the levels of Sirt1. After treatment with Sirt1 inhibitor, western blot, RT-PCR and immunofluorescence staining showed that neural genes and protein markers had markedly decreased. Additionally, the ERK and AKT signaling pathway played a key role in the neural differentiation of DPSCs stimulated with bFGF + NGF. These results suggested that manipulation of the ERK and AKT signaling pathway may be associated with the differentiation of bFGF and NGF treated DPSCs. Our date provided theoretical basis for DPSCs to treat neurological diseases and repair neuronal damage.

Kinase Signaling in Apoptosis Induced by Saturated Fatty Acids in Pancreatic β-Cells

Pancreatic β-cell failure and death is considered to be one of the main factors responsible for type 2 diabetes. It is caused by, in addition to hyperglycemia, chronic exposure to increased concentrations of fatty acids, mainly saturated fatty acids. Molecular mechanisms of apoptosis induction by saturated fatty acids in β-cells are not completely clear. It has been proposed that kinase signaling could be involved, particularly, c-Jun N-terminal kinase (JNK), protein kinase C (PKC), p38 mitogen-activated protein kinase (p38 MAPK), extracellular signal-regulated kinase (ERK), and Akt kinases and their pathways. In this review, we discuss these kinases and their signaling pathways with respect to their possible role in apoptosis induction by saturated fatty acids in pancreatic β-cells.

Neuroactive molecules and growth factors modulate cytoskeletal protein expression during astroglial cell proliferation and differentiation in culture

Steroid hormones and neurotrophic factors regulate astroglial cell survival, proliferation, and differentiation in culture. The present study examines the interaction between glucocorticoids and growth factors (GFs) on cytoskeletal proteins and extracellular signal-regulated kinase 2 (ERK2) expression in stressed astroglial cultures at 25 days in vitro, according to the following experimental condition. Pretreatment with basic fibroblast growth factor alone or in combination with dexamethasone 10(-9) M for 48 hr induced an enhancement of glial fibrillary acidic protein, vimetin, and ERK2 expression. Treatment with "progression" GFs alone and in the last 12 hr significantly increased the above-mentioned markers' expression. The present study shows that glucocorticoids may cooperate with GFs or may abrogate their effects, depending on the experimental culture conditions used as well as the exposure time and the types of GFs added. Our findings provide evidence of interactive dialogue between GFs and neurosteroids in cultured astrocytes. This may have implications in the therapeutic approach to neurologic disorders associated with astrogliosis.