Neurite Growth-promoting Factor Research Articles

Environmental enrichment improves declined cognition induced by prenatal inflammatory exposure in aged CD-1 mice: Role of NGPF2 and PSD-95.

Research suggests that prenatal inflammatory exposure could accelerate age-related cognitive decline that may be resulted from neuroinflammation and synaptic dysfunction during aging. Environmental enrichment (EE) may mitigate the cognitive and synaptic deficits. Neurite growth-promoting factor 2 (NGPF2) and postsynaptic density protein 95 (PSD-95) play critical roles in neuroinflammation and synaptic function, respectively. We examined whether this adversity and EE exposure can cause alterations in Ngpf2 and Psd-95 expression. In this study, CD-1 mice received intraperitoneal injection of lipopolysaccharide (50 μg/kg) or normal saline from gestational days 15-17. After weaning, half of the male offspring under each treatment were exposed to EE. The Morris water maze was used to assess spatial learning and memory at 3 and 15 months of age, whereas quantitative real-time polymerase chain reaction and Western blotting were used to measure hippocampal mRNA and protein levels of NGPF2 and PSD-95, respectively. Meanwhile, serum levels of IL-6, IL-1β, and TNF-α were determined by enzyme-linked immunosorbent assay. The results showed that aged mice exhibited poor spatial learning and memory ability, elevated NGPF2 mRNA and protein levels, and decreased PSD-95 mRNA and protein levels relative to their young counterparts during natural aging. Embryonic inflammatory exposure accelerated age-related changes in spatial cognition, and in Ngpf2 and Psd-95 expression. Additionally, the levels of Ngpf2 and Psd-95 products were significantly positively and negatively correlated with cognitive dysfunction, respectively, particularly in prenatal inflammation-exposed aged mice. Changes in serum levels of IL-6, IL-1β, and TNF-α reflective of systemic inflammation and their correlation with cognitive decline during accelerated aging were similar to those of hippocampal NGPF2. EE exposure could partially restore the accelerated decline in age-related cognitive function and in Psd-95 expression, especially in aged mice. Overall, the aggravated cognitive disabilities in aged mice may be related to the alterations in Ngpf2 and Psd-95 expression and in systemic state of inflammation due to prenatal inflammatory exposure, and long-term EE exposure may ameliorate this cognitive impairment by upregulating Psd-95 expression.

NGPF2 triggers synaptic scaling up through ALK-LIMK-cofilin-mediated mechanisms.

Synaptic scaling is an extensively studied form of homeostatic plasticity critically involved in various brain functions. Although it is accepted that synaptic scaling is expressed through the postsynaptic accumulation of AMPA receptors (AMPARs), the induction mechanism remains elusive. In this study, we show that TTX treatment induces rapid but transient release of the neurite growth-promoting factor 2 (NGPF2), and this release is necessary and sufficient for TTX-induced scaling up. In addition, we show that inhibition of the anaplastic lymphoma kinase (ALK)-LIMK-cofilin signaling pathway blocks TTX- and NGPF2-induced synaptic scaling up. Furthermore, we show that TTX-induced release of NGPF2 is protein synthesis dependent and requires fragile X mental retardation protein 1 (FMRP1). These results indicate that activity blockade induces NGPF2 synthesis and release to trigger synaptic scaling up through LIMK-cofilin-dependent actin reorganization, spine enlargement, and stabilization of AMPARs at the synapse.

The Possible Interactions and Therapeutic Roles of Lithium Chloride and Midkine on Cancer Treatment.

Midkine (MK) is a heparin-binding anti-apoptotic growth factor or cytokine also known as neurite growth-promoting factor 2 (NEGF2). It is developmentally an important retinoic acid-responsive gene product strongly induced during the mid-gestation stage. Midkine promotes different cellular events such as cell growth, differentiation, survival, gene expression, and drug resistence. Midkine, the phosphatidylinositol 3-kinases (PI3-kinase, PI3K) and glycogen synthase kinase-3 beta (GSK-3β) inhibitors together with lithium chloride may be a very effective treatment modality, especially in tumors with high expression of these two molecules. PI3 kinase and GSK-3β, both serine threonine kinases located in the center of the signaling network, are very important regulator molecules for cell survival or death. Lithium chloride (LiCl), with its newly discovered antineoplastic effect and cytotoxicity potentiation, has become a promising agent in the application of new combination treatments. Although the LiCl mechanism of action is still not fully understood, previous studies have shown that LiCl is an inhibitör of the inositol monophosphatase (IMPase) and GSK-3β. GSK-3β, is a serine-threonine protein kinase involved in cell proliferation, differentiation, survival, apotosis, and tumorogenesis. The role of GSK-3β in tumorigenesis and cancer remains controversial. It may have a function as a tumor suppressor for certain types of tumors, but it promotes cell growth and development in other tumor types.

Validation of the diagnostic utility of urinary midkine for the detection of bladder cancer.

As it has been demonstrated previously that midkine (also known as neurite growth-promoting factor 2) protein levels in urine of bladder cancer (BCa) patients are increased compared to healthy controls, the present study validated the diagnostic utility of midkine in an independent patient cohort and compared the observed values with voided urine cytology (VUC), which is the current reference standard for non-invasive diagnosis of BCa. Voided urine samples were prospectively collected from 92 BCa patients and 70 control subjects. Protein levels of midkine were assessed using a commercially available enzyme-linked immunosorbent assay and normalized to urinary creatinine. The diagnostic performance of urinary midkine was evaluated by receiver operating characteristic curves. The best combinations of sensitivities and specificities were determined by Youden's Index. Midkine concentrations were significantly elevated in urine samples from BCa patients compared to controls (P<0.001; Mann-Whitney U Test). The level of midkine was associated with disease progression, with the highest concentrations in urine specimens of patients with pT1 and ≥pT2a, as well as high-grade tumors (P<0.001; Mann-Whitney U test). Sensitivities of urinary midkine and VUC were 69.7 and 87.6%, respectively. The corresponding specificities for midkine and VUC were 77.9 and 87.7%, respectively. The combined use of VUC and midkine improved the sensitivity to 93.3%, but reduced the specificity to 66.2%. Despite its reduced discriminatory power for low-grade and low-stage BCa, urinary midkine can be utilized for the identification of high-grade pT1 and ≥pT2a tumors. This means that midkine may potentially be suitable for the identification of patients with high risk BCa.

Clinical significance of midkine expression in sporadic desmoid tumors.

The aim of the present study was to identify the prognostic factors for the propensity for recurrence in sporadic desmoid tumors. The catenin (cadherin-associated protein) β1 (CTNNB1) genotypes and expression of Wnt pathway proteins and midkine (also termed neurite growth-promoting factor 2) were investigated in 159 patients with sporadic desmoid tumors. Formalin-fixed paraffin-embedded tissues of the surgically resected desmoid tumors were examined by direct sequencing of CTNNB1 exon 3, and immunostained for the expression of β-catenin, T-cell factor 4 (TCF-4), phosphorylated protein kinase B (pAkt), midkine and menin using a tissue microarray method. Among the samples, 70% (111/159) exhibited point mutations of the CTNNB1 gene, including T41A (56%), S45F (8%), S45P (2%), S45N (2%) and T42A (1%). In addition, 100, 57, 24, 15 and 92% of the tumors expressed β-catenin, TCF-4, midkine, pAkt and menin, respectively. Positive midkine expression was significantly associated with the recurrence of tumors (P=0.001). The multivariate analysis of recurrence demonstrated that an extra-abdominal tumor site [hazard ratio (HR), 2.625; P=0.001] and midkine expression (HR, 2.077; P<0.009) were independent prognostic factors of tumor recurrence. In conclusion, the present results suggest that the tumor site and midkine expression may be predictive markers for the recurrence of sporadic desmoid tumors.

Midkine neurite growth-promoting factor 2 expression as a potential prognostic marker of adjuvant therapy in head and neck squamous cell carcinoma

Objective: The prognostic function of neurite growth-promoting factor 2 (Midkine (MK)) in adjuvant treatment of head and neck squamous cell carcinoma (HNSCC) is unclear. This study examined whether MK expression may predict treatment response and survival in resectable HNSCC patients.Methods: In this retrospective study, MK expression in 144 HNSCC patients was analyzed by immunohistochemistry. A subset of patients (n = 10) had MK expression levels analyzed by western blot and semi-quantitative reverse transcription polymerase chain reaction. Data were analyzed using the Log-rank test and α = 0.05.Results: Expression of MK was associated with poorer five-year progression-free and overall survival rates in HNSCC patients (p = 0.002).Conclusion: MK might play an important role in the progression of HNSCC and may be a useful prognostic factor.

Pleiotrophin promotes perineural invasion in pancreatic cancer

Perineural invasion (PNI) in pancreatic cancer is an important cause of local recurrence, but little is known about its mechanism. Pleiotrophin (PTN) is an important neurotrophic factor. It is of interest that our recent experimental data showed its involvement in PNI of pancreatic cancer. PTN strongly presents in the cytoplasm of pancreatic cancer cells, and high expression of PTN and its receptor may contribute to the high PNI of pancreatic cancer. Correspondingly, PNI is prone to happen in PTN-positive tumors. We thus hypothesize that, as a neurite growth-promoting factor, PTN may promote PNI in pancreatic cancer. PTN is released at the time of tumor cell necrosis, and binds with its high-affinity receptor, N-syndecan on pancreatic nerves, to promote neural growth in pancreatic cancer. Furthermore, neural destruction leads to a distorted neural homeostasis. Neurons and Schwann cells produce more N-syndecan in an effort to repair the pancreatic nerves. However, the abundance of N-syndecan attracts further PTN-positive cancer cells to the site of injury, creating a vicious cycle. Ultimately, increased PTN and N-syndecan levels, due to the continuous nerve injury, may promote cancer invasion and propagation along the neural structures. Therefore, it is meaningful to discuss the relationship between PTN/N-syndecan signaling and PNI in pancreatic cancer, which may lead to a better understanding of the mechanism of PNI in pancreatic cancer.

Diethylphthalate, Possible Interactions in Fetal Brain Development

Many natural and synthetic compounds, including a variety of the chemicals used as plasticizers or in the pro- duction of cosmetics and therapeutics, have steroid agonist or antagonist activities, altering hormone-regulated gene ex- pression. The phthalate (diethylphthalate, extensively used as a plasticizer and in consumer products, are evaluated using the human renal epithelial cell line 293T/17. Emphasis of the study was on genes essential for central nervous system de- velopment or function. Cells were treated with 1, 10 or 100 μM phthalate and gene expression was measured in treated cells, showing significant up- or down-regulation of a large number of genes in treated compared to untreated cells. Of the 19,000 human genes on the DNA array chip utilized, two specific genes, FGD1 and NGPF2, were selected to corroborate mRNA levels using quantitative real time PCR (qrtPCR) data to confirm results obtained from the microarray determina- tions. FGD1 (faciogenital dysplasia) and NGPF2 (neurite growth-promoting factor 2, also called Midkine, MDK), showed a significant, possibly estrogen-synergistic, down-regulation of genes essential for fetal brain development. These studies were designed to provide data on the gene expression-altering capacity of a widely distributed chemical, diethylphthalate (DEP), and to show possible associations between the previously reported widespread presence of DEP and the DEP me- tabolite, MEP, in urine samples from a reference population, the potential for altered gene expression in human cells in vi- tro, and possible neurodevelopmental effects that could be correlated with in utero exposure to DEP.

Pleiotrophin Expression in Human Pancreatic Cancer and Its Correlation with Clinicopathological Features, Perineural Invasion, and Prognosis

Pleiotrophin (PTN), a heparin-binding growth factor also known as neurite growth-promoting factor, exhibits several properties related with tumor development. PTN and its receptor, N-syndecan, may play a very important role in tumor growth and neural invasion of pancreatic cancer. We investigated PTN and N-syndecan protein levels in 38 patients with pancreatic cancer by immunohistochemistry, and analyzed for its correlation with clinicopathological features, perineural invasion, and prognosis. The results showed that PTN and N-syndecan proteins were found in 24 (63.2%) and 22 (57.9%) specimens, respectively. PTN and N-syndecan expressions were associated with perineural invasion (P = 0.016 and P = 0.029, respectively). High PTN expression was closely related to an advanced TNM stage (P = 0.007), lymph node metastasis (P = 0.040), and decreased postoperative survival at 3 years (50.0% versus 20.8%, respectively; P = 0.001). We conclude that high expression of PTN combined with N-syndecan may contribute to the increased perineural invasion and poor prognosis of pancreatic cancer.

Crystal structure of human PEDF, a potent anti-angiogenic and neurite growth-promoting factor.

Pigment epithelium-derived factor (PEDF), a noninhibitory member of the serpin superfamily, is the most potent inhibitor of angiogenesis in the mammalian ocular compartment. It also has neurotrophic activity, both in the retina and in the central nervous system, and is highly up-regulated in young versus senescent fibroblasts. To provide a structural basis for understanding its many biological roles, we have solved the crystal structure of glycosylated human PEDF to 2.85 A. The structure revealed the organization of possible receptor and heparin-binding sites, and showed that, unlike any other previously characterized serpin, PEDF has a striking asymmetric charge distribution that might be of functional importance. These results provide a starting point for future detailed structure/function analyses into possible mechanisms of PEDF action that could lead to development of therapeutics against uncontrolled angiogenesis.

Life-long overexpression of S100β in Down’s syndrome: implications for Alzheimer pathogenesis

Chronic overexpression of the neurite growth-promoting factor S100β has been implicated in the pathogenesis of neuritic plaques in Alzheimer’s disease. Such plaques are virtually universal in middle-aged Down’s syndrome, making Down’s a natural model of Alzheimer’s disease. We determined numbers of astrocytes overexpressing S100β, and of neurons overexpressing β-amyloid precursor protein (β-APP), and assayed for neurofibrillary tangles in neocortex of 20 Down’s syndrome patients (17 weeks gestation to 68 years). Compared to controls, there were twice as many S100β-immunoreactive (S100β +) astrocytes in Down’s patients at all ages: fetal, young, and adult ( p = 0.01, or better, in each age group). These were activated (i.e., enlarged), and intensely immunoreactive, even in the fetal group. There were no neurofibrillary changes in fetal or young Down’s patients. The numbers of S100β + astrocytes in young and adult Down’s patients correlated with the numbers of neurons overexpressing β-APP ( p < 0.05). Our findings are consistent with the idea that conditions—including Down’s syndrome—that promote chronic overexpression of S100β may confer increased risk for later development of Alzheimer’s disease.

Spinal cord neurite growth response to target tissue in a dose-dependent manner in vitro.

Neurite outgrowth from larval frog spinal cord explants in tissue culture previously has been shown to be enhanced and oriented in the presence of mesenchymal limb target tissue. Evidence that suggests the limb mesenchyme is the source of a motor neuron growth factor has prompted consideration of a possible target dose relationship in eliciting spinal neurite growth. Whereas typical experimental paradigms incorporate a single target explant in cocultures of neural and target tissues, we have challenged spinal cord explants with dual limb targets. Both the spinal cord explants and mesenchymal limb tissue segments were derived from young stage V Rana pipiens tadpoles. In comparison to cultures with a single limb, the spinal neurite density in the presence of two limbs increased more than twofold. Accompanying the increase in neuritic quantity was a substantial increase in the average length of the neurites. Over a two-week culture period there was little change in the relative differences between the single and double target cultures. Even though the double target tissues were placed adjacent to one another on one side of the cord explant, greatly enhanced neurite growth occurred on the contralateral side as well. The dramatic increase in neurite outgrowth in the presence of an additional target tissue provides further evidence that undifferentiated mesenchymal limb tissue is the source of a spinal neurite growth-promoting factor that may act in a dose-dependent manner with implications for both motor axon growth regulation and regeneration.

S5.5 HB-GAM (pleiotrophin), an extracellular matrix-associated neurite growth-promoting factor that interacts with heparin-type carbohydrate chains

S5.5 HB-GAM (pleiotrophin), an extracellular matrix-associated neurite growth-promoting factor that interacts with heparin-type carbohydrate chains

Evidence that the B2 chain of laminin is responsible for the neurite outgrowth-promoting activity of astrocyte extracellular matrix

Extracellular matrix (ECM) derived from cerebral cortical astrocytes stimulates neurite outgrowth from pheochromocytoma (PC12) cells in the absence of the classical nerve growth factor (NGF). We have shown here that astrocyte ECM can also stimulate neurite outgrowth from primary cultures of central nervous system (CNS) neurons. Using PC12 cells for a quantitative assay, we also demonstrated that the neurite growth-promoting activity increased as the astrocytes matured in vitro: ECM from older astrocytes (3–12 weeks in vitro) exhibited two-fold more neurite growth-promoting activity than ECM for younger astrocytes (5 days to 2 weeks in vitro). We applied various antibodies to identify the neurite growth-promoting factor of astrocyte ECM and found that anti-laminin inhibited neurite outgrowth by 50%, whereas anti-fibronectin and anti-NGF had no effect. Immunoblots, using laminin chain-specific antibodies, and cDNA hybridization of laminin mRNA demonstrated that cultured astrocytes synthesize only the B2 chain of laminin. This suggests that the B2 chain of laminin suffices to stimulate neurite outgrowth.

Substrate-bound nerve growth factor promotes neurite growth in peripheral nerve

Nerve growth factor (NGF), in addition to its well-known effects as a soluble neurite growth-promoting factor, also appears to promote the elongation of neurites when it is adsorbed to tissue culture substrates. Peripheral nerve Schwann cells appear to possess a receptor for NGF on theit surfaces which is induced substantially after axotomy. We have found that the adsorption of NGF onto cryostat sections of the distal stump of previously severed sciatic nerve enhances neurite growth over this tissue. This finding, coupled with the two previous observations, suggests that Schwann cell surface NGF receptors serve to bind to NGF-like growth factors so as to provide favorable surfaces for regenerating peripheral nerve axons.

Separate factors produced by the CNS of the snail Helisoma stimulate neurite outgrowth and choline metabolism in cultured neurons.

Neurons from the snail Helisoma require a brain-derived factor(s) for neurite outgrowth in both organ and isolated cell culture. This factor is released from the CNS of Helisoma when brains are incubated in defined medium, producing a conditioned medium (CM). In addition to its growth-promoting activity, CM also enhances total uptake of 3H-choline and the incorporation of 3H-choline into specific metabolites: acetylcholine, phosphorylcholine and lipid. This choline metabolism-enhancing factor(s) is distinct and separable from neurite growth-promoting factor: 1. Over 95% of neurite growth-promoting activity can be removed from CM by adsorption to a polylysine surface while there is no loss of choline metabolism-enhancing activity. 2. When central ganglia were treated with anisomycin, a potent inhibitor of molluscan protein synthesis, the choline metabolism-enhancing activity was completely absent from the resulting CM, while the growth promoting activity was reduced by only 35%. These results suggest that the Helisoma CNS produces a variety of trophic factors that are involved in regulating the interaction between neuronal growth and metabolism.