Insulin-like growth factor I interfaces with brain-derived neurotrophic factor-mediated synaptic plasticity to modulate aspects of exercise-induced cognitive function

The ability of exercise to benefit neuronal and cognitive plasticity is well recognized. This study reveals that the effects of exercise on brain neuronal and cognitive plasticity are in part modulated by a central source of insulin-like growth factor-I. Exercise selectively increased insulin-like growth factor-I expression without affecting insulin-like growth factor-II expression in the rat hippocampus. To determine the role that insulin-like growth factor-I holds in mediating exercise-induced neuronal and cognitive enhancement, a specific antibody against the insulin-like growth factor-I receptor was used to block the action of insulin-like growth factor-I in the hippocampus during a 5-day voluntary exercise period. A two-trial-per-day Morris water maze was performed for five consecutive days, succeeded by a probe trial 2 days later. Blocking hippocampal insulin-like growth factor-I receptors did not significantly attenuate the ability of exercise to enhance learning acquisition, but abolished the effect of exercise on augmenting recall. Blocking the insulin-like growth factor-I receptor significantly reversed the exercise-induced increase in the levels of brain-derived neurotrophic factor mRNA and protein and pro-brain-derived neurotrophic factor protein, suggesting that the effects of insulin-like growth factor-I may be partially accomplished by modulating the precursor to the mature brain-derived neurotrophic factor. A molecular analysis revealed that exercise significantly elevated proteins downstream to brain-derived neurotrophic factor activation important for synaptic function, i.e. synapsin I, and signal transduction cascades associated with memory processes, i.e. phosphorylated calcium/calmodulin protein kinase II and phosphorylated mitogen-activated protein kinase II. Blocking the insulin-like growth factor-I receptor abolished these exercise-induced increases. Our results illustrate a possible mechanism by which insulin-like growth factor-I interfaces with the brain-derived neurotrophic factor system to mediate exercise-induced synaptic and cognitive plasticity.

[CD4+CD25high regulatory cells in peripheral blood of nasopharyngeal carcinoma]

OBJECTIVE

The current study was designed to investigate the changes in peripheral CD4+ CD25high regulatory T cells (CD4+ CD25high Tr) in nasopharyngeal carcinoma (NPC).

METHOD

The peripheral was collected blood from 54 patients with NPC and 15 healthy controls, by using monoclonal antibodies, the blood samples were evaluated with the flow cytometry for lymphocyte subsets and Tr cells.

RESULT

The proportion of CD4+ T cells, and the ratio of CD4+/CD8+ in NPC group was significantly less than those of the healthy controls (P < 0.05), but the proportion of CD4+ CD25high Tr cells was higher than those in controls (P < 0.01). The proportion of CD4+ CD25high Tr cells in the late stage was higher than those in the early stage [(stages I + II (2.28 +/- 1.07) %; stage III (3.65 +/- 1.21) %; stage IV (4.72 +/- 0.87) %)]. Comparing with the stages I + II, the proportion of CD4+ CD25high Tr cells in the stage III or IV was higher than those in controls (P < 0.01); and more, the proportion of CD4+ CD25high Tr cells in the stage IV was higher than those in the stage III (P < 0.01).

CONCLUSION

The relative increase in CD4+ CD25high Tr cells in peripheral blood may be related to immunosuppression and tumor progression in patients with NPC. This finding suggests that CD4+ CD25high Tr cells in peripheral blood of NPC may be positive for prognosis analysis. Deletion of the CD4+ CD25high Tr cells may induce tumor immunity effectively and may be a new tumor treatment method.

Study on the relationship between G1057D variants of IRS2 gene and obese T2DM in Chinese Han subjects

OBJECTIVE

To investigate the relationship between the G1057D variants of insulin receptor substrate-2(IRS2) gene and type 2 diabetes mellitus (T2DM) in subjects.

METHODS

Four hundred and thirty-nine Chinese Han subjects, including 218 patients with T2DM and 221 normal controls, were selected from the Hans in the Liaoning area, and each group was divided into two subgroups according to body mass index. The G1057D variants of IRS2 were detected by polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) and their relationships with T2DM were analyzed.

RESULTS

(1) The frequency of G1057D variant was 29% in all subjects. The frequency of DD genotype was significantly lower in non-obese DM group than in non-obese control group. The Logistic regression analysis showed that the odds ratio of DD genotype was 0.265. The frequency of DD genotype was significantly higher in obese DM group than in obese control group. The Logistic regression analysis showed that the odds ratio of DD genotype was 3.991. (2) In the non-obese control group, the FPG and 2hCP of DD genotypes were lower than those of GG genotypes (P< 0.05, P< 0.01), the HOMA-B of DD genotypes was higher than that of GG genotype (P< 0.01). In the non-obese DM group, the waistline/hip ratio (WHR) of DD genotypes was higher than that of GG genotypes(P< 0.01). In the obese DM group, the WHR, HOMA-IR, 2hPG, 2hINS and 2hCP levels of DD genotypes were higher than those of GG genotypes, while the level of HOMA-B of DD genotypes was lower than that of GG genotypes. In the obese control group, the WHR, HOMA-IR, 2hPG, 2hINS and 2hCP levels of DD genotype were higher than those of GG genotype, and the HOMA-B level of DD genotype was lower than that of GG genotypes (P< 0.05).

CONCLUSION

The relationships between G1057D variants of IRS2 and T2DM are mediated by obesity.

Prothrombin Shanghai: hypoprothrombinaemia caused by substitution of Gla29 by Gly

Prothrombin deficiency is a rare bleeding disorder inherited as an autosomal recessive trait. In this study, we reported a Chinese family with hereditary prothrombin deficiency. The proposita had a prolonged activated partial thromboplastin time (APTT, 71.6 s) and prothrombin time (PT, 28.0 s). The coagulation factors activities were normal except that prothrombin coagulation activity was markedly reduced, and the prothrombin antigen level was moderately decreased. Nucleotide sequencing of amplified DNA revealed a novel mutation, Glu (GAG) to Gly (GGG) at residue 29, which normally undergoes gamma-carboxylation within the Gla domain of prothrombin. The proposita was identified as homozygous, while her father, mother and maternal grandmother were heterozygous for the mutation. Gla29 has been demonstrated as one of the key residue for Ca2+-binding, membrane interaction and biological activity of prothrombin.

[Antiestrogenic effect of 2,3,7,8-tetrachlorodibenzo-p-dioxin on the gene expression of insulin-like growth factors family in osteoblast cells]

OBJECTIVE

To investigate the antiestrogenic effect of environment teratogen on the gene expression of insulin-like growth factors (IGFs) family in osteoblast cells during rat skeleton development.

METHODS

The fetal rat models with congenital skeleton malformation were constructed by treating 20 female Wistar rats with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on pregnant day 10. The MC-3T3-E1 cells were cultured with estrogen, TCDD, or a combination of the two chemicals for 24 hours. The IGF-II and IGFBP-6 mRNA levels in rat calvaria bone tissue and MC-3T3-E1 cells were detected by reverse transcription-polymerase chain reaction. Flow cytometer was used to determine the cell proliferation.

RESULTS

TCDD at the concentration of 5-15 microg/kg induced developmental skeleton defect of fetal rat, and the effect was dose-dependent. The expression of IGF-II mRNA gene was enhanced by estrogen in rat calvaria bone tissue and MC-3T3-E1 cells, whereas IGFBP-6 mRNA was decreased. Estrogen increased the cell proliferation in MC-3T3-E1 cells. TCDD, however, inhibited the effect of estrogen on regulation of IGF-II gene and IGFBP-6 gene as well as MC-3T3-E1 cell proliferation.

CONCLUSION

These findings provide the evidence that TCDD can induce congenital fetal skeleton malformation under the condition of high estrogen level in pregnant Wistar rats. TCDD has antiestrogenic effect and hence exerts negative influence on the osteoblast cells through target IGF-II and IGFBP-6 of IGFs family.

[Effect of SH2A gene in cell signal transduction and its subcellular locolization]

OBJECTIVE

To examine the effect of SH2A gene in cell signal transduction and its subcellular localization.

METHODS

RT-PCR method was used to amplify the coding sequence of SH2A gene. Eukaryotic recombined expression vector pcDNA 3.1-SH2A was constructed, and then Bel7402 cell and COS7 cell transfected by liposome. Multiple kinase assay was performed to examine the activity of protein kinase (PKC), mitogen activated protein kinase (MAPK), tyrosine protein kinase (TPK) in the transfected cells. Meantime, pEGFP-SH2A vector was also constructed and the cells transfected with it were examined by fluorescent microscopy.

RESULTS

Recombined expression vector pcDNA3.2-SH2A and pEGFP-SH2A contained the coding sequence of SH2A cDNA. In both cell lines expressing SH2A gene, the cytoplasm PKC activity decreased by 40% or so, but no apparent alteration was found in MAPK and TPK activity. SH2A gene was found localized in the cytoplasm of transfected cells under fluorescent microscope.

CONCLUSION

SH2A gene may act as an inhibiting factor in PKC signal transduction, and it is localized in cytoplasm.

Type I coagulation factor V deficiency caused by compound heterozygous mutation of F5 gene

A 16-year-old Chinese female with prolonged bleeding after surgery has been studied. Routine clotting tests revealed a prolonged activated partial thromboplastin time (APTT; 126.6 s) and prothrombin time (PT; 42.8 s). The coagulation factors activities were normal except for factor V, which was only 0.3% of normal. DNA analysis of the FV gene revealed five nucleotide substitutions in exons, including two silent mutations (G327A and A5112G), one polymorphism (G1628A), a G1348T missense mutation and 4887 approximately 8delG. These abnormalities were associated with her FV deficiency, perhaps by causing a Gly392Cys substitution in FV amino acid sequence or by introducing a premature stop codon at amino acid position 1390. This is the third case in which FV deficiency is caused by compound heterozygous mutation of F5 gene, and is the first report from a Chinese family.

[Correlation analysis between WNK4 gene and essential hypertension]

OBJECTIVE

To investigate association of mutation in WNK4 gene with essential hypertension and to analyze the expression of WNK4 gene.

METHODS

cSNP in WNK4 gene in a small samples was detected by sequencing, then PCR-RFLP was performed in 98 patients with essential hypertension and 95 control subjects. The expression profile of WNK4 gene was tested by RT-PCR.

RESULTS

A cSNP was detected in WNK4 gene exon7 G1662A, and there were significant differences in the distribution of allele frequency of G1662A between essential hypertension group and control group. WNK4 gene were expressed in the tissues of kidney, brain, lung, heart, spleen and intestine of fetus.

CONCLUSION

WNK4 gene is well correlated with essential hypertension.

[Distribution and significance of cSNP in KCNA7 gene as a novel NIDDM candidate gene in the population of northeast China]

To investigate the distribution and significance of a coding single nucleotide polymorphism (cSNP) of the novel NIDDM candidate gene,KCNA7 in the population of Northeast China, 97 patients with NIDDM and 141 controls were tested. Genotypes of KCNA7 gene T418M(C/T) were performed by PCR-RFLP, and SSCP was used to detect other unknown variations near the C/T site of KCNA7 gene. As a result, no significant difference was observed in the distribution of genotypes of T418M(C/T) between NIDDM and control group. Clinical biochemical examinations showed no significant difference between genotypes in both INDDM and control group, and no other SNPs were found near the C/T site of KCNA7 gene. This study demonstrates the frequency of this cSNP complies well with the Hardy-Weinberg equilibrium in normal group, T418M(C/T) is only a polymorphic maker of KCNA7 gene,and the possibility of association between NIDDM and KCNA7 can not be excluded.

Gene therapy of HSV-TK transferred by the EBV based expression vector on experimental hepatocellular carcinoma

To study the therapeutic effects of herpes simplex virus thymidine kinase (HSV-TK) gene transferred by the EBV-based expression vector (pDR2) on experimental hepatocellular carcinoma, pDR2-TK gene was delivered into human hepatocellular carcinoma cell line SMMC-7721 by using liposome-mediated transfection technique, and then gene expression was detected by RT-PCR, and the killing effects were examined through MTT method. In the nude mice hepatoma model, the antitumor effects of pDR2-TK/GCV system was evaluated in terms of tumor growth. MTT results showed that the pDR2-TK/GCV had cytotoxic effect and about 70% SMMC-7721 cells were killed when GCV was at 1000 mumol/L. In vivo experiment showed that the tumor size in nude mice with transferred pDR2-TK gene was significantly smaller than that in control group (P < 0.01). On the 10th day the tumor in 3 mice (60%) disappeared completely after GCV treatment. It is concluded that the pDR2-TK/GCV system has marked killing effects on the experimental hepatocellular carcinoma.

[A novel member of SH(2) signaling protein family: cloning and characterization of SH(2)A gene]

OBJECTIVE

Cloning and characterization of a novel gene by exon trapping and exon linking at chromosome 8p22.

METHODS

A novel gene was cloned using exon trapping and exon linking, and its expression was determined by reverse transcription-polymerase chain reaction (RT-PCR) and Northern blot.

RESULTS

A sequence containing 3 exons was found. The sequence is homologous with the putative gene AK024799 which consists of 2880 bp cDNA with 1362 bp open reading frame and codes 454 amino acids with an SH(2) domain. The gene was named SH(2)A at chromosome 8p22. SH(2)A gene is ubiquitously expressed in various tissues with three transcripts. The aberrant expression of SH(2)A gene in some cancers was detected.

CONCLUSION

SH(2)A is a novel docking protein of SH(2) signaling protein family, which may play an important role in cellular signal transduction. It relates to the pathogenesis of tumor.

The complete nucleotide sequence of Beet black scorch virus (BBSV), a new member of the genus Necrovirus

The complete nucleotide sequence of Beet black scorch virus (BBSV) was determined. The BBSV genome is composed of 3641 nucleotides and has similar organization with Tobacco necrosis virus D of 61% nucleotide identity. The 5'-proximal open reading frame (ORF) encodes a putative 23 kDa protein and a 82 kDa protein by reading-through of an amber termination codon. Three small ORFs located in the center of the genome may encode for a 4.2 kDa protein and two 7 kDa proteins. The 3'-proximal ORF encodes a 24.5 kDa protein equivalent in mass to the viral coat protein. Considering biological and molecular similarities with TNV, it is concluded that BBSV is a new member of the genus Necrovirus.

[Polymorphism analysis of 825C/T of the G-protein beta 3 subunit in high risk population of hypertension in the northeast China]

PCR-RFLP was used for genotyping of GNB3 C/T in 133 patients with EH and 257 healthy control subjects in the high risk population and in 98 patients with EH and 110 healthy control subjects in general population. Some biochemical tests were performed also. The association between the polymorphism and blood pressure was analyzed by the case-control study. Not association between GNB3 825C/T polymorphism and blood pressure was found in both populations. CT and TT genotypes in women of the high risk population are associated with diastolic blood pressure, serum sodium and calcium. Although GNB3 is not a susceptible gene of hypertension in the northeast Chinese, it still has some effects on regulation of the blood pressure in susceptible women.

[Cloning and analysis of human alpha-1B glycoprotein precursor gene: a novel member of human immunoglobulin superfamily]

A cDNA of 1694 bp was cloned from human liver Marathon cDNA by means of Rapid Amplification of cDNA Ends (RACE). The cDNA has an open reading frame at 43-1530 bp encoding 495 amino acid residues and a 17-residue signal peptide. There are four Igc2 domains in the translated polypeptide, which is highly homologous to the human alpha-1B glycoprotein isolated from human plasma. Upon this, we conclude that this cDNA is the alpha-1B glycoprotein precursor gene which has never been cloned before, and it may be a novel member of immunoglobulin superfamily and may involved in the cell recognition and the regulation of cell behavior.

Phosphorylation of the CCAAT displacement protein (CDP)/Cux transcription factor by cyclin A-Cdk1 modulates its DNA binding activity in G(2)

Stable DNA binding by the mammalian CCAAT displacement protein (CDP)/Cux transcription factor was previously found to be up-regulated at the G(1)/S transition as the result of two events, dephosphorylation by the Cdc25A phosphatase and proteolytic processing, to generate an amino-truncated isoform of 110 kDa. In S phase, CDP/Cux was shown to interact with and repress the core promoter of the p21(WAF1) gene. Here we demonstrate that DNA binding by p110 CDP/Cux is down-modulated as cells progress into G(2). Accordingly, cyclin A-Cdk1 was found to bind to CDP/Cux and modulate its DNA binding activity in vitro and in vivo. Interaction with CDP/Cux required the presence of both cyclin A and a cyclin-dependent kinase (Cdk)-activating kinase-activated Cdk1 and involved the Cut homeodomain and a downstream Cy motif. Phosphorylation of serines 1237 and 1270 caused inhibition of DNA binding in vitro. In cotransfection studies, cyclin A-Cdk1 inhibited CDP/Cux stable DNA binding and prevented repression of the p21(WAF1) reporter. In contrast, mutant CDP/Cux proteins in which serines 1237 and 1270 were replaced with alanines were not affected by cyclin A-Cdk1. In summary, our results suggest that the phosphorylation of CDP/Cux by cyclin A-Cdk1 contributes to down-modulate CDP/Cux activity as cells progress into the G(2) phase of the cell cycle.

TGF-beta1 up-regulates paxillin protein expression in malignant astrocytoma cells: requirement for a fibronectin substrate

Cytokines can influence the interactions between members of the integrin cell adhesion receptor family and the extracellular matrix thereby potentially affecting cell function and promoting cell adhesion, growth and migration of malignant astrocytoma tumor cells. As malignant astrocytoma cells synthesize TGF-beta1 in vivo, we analysed the effects of TGF-beta1 on signaling events associated with integrin receptor ligation, focusing on the effects on paxillin, a phosphorylated adaptor protein, that acts as a scaffold for signaling molecules recruited to focal adhesions. TGF-beta1-stimulation of primary astrocytes and serum-starved U-251MG malignant astrocytoma cells attached to fibronectin induced a substantial increase in the levels of paxillin protein (fivefold increase at 2.0 ng/ml) in a dose- and time-dependent manner compared to the levels observed on plating onto fibronectin in the absence of stimulation. In the astrocytoma cells, this resulted in an increase in the pool of tyrosine-phosphorylated paxillin, although it did not appear to alter the extent of phosphorylation of the paxillin molecules. In contrast, in primary astrocytes the protein levels were upregulated in the absence of a parallel increase in phosphorylation. The TGF-beta1-stimulated increase in paxillin levels required ligation of the fibronectin receptor, as it was not induced when the cells were plated onto vitronectin, collagen or laminin. The increase in the pool of paxillin on TGF-beta1 stimulation of the fibronectin-plated astrocytoma cells was associated with an increase in translation, but was not associated with an increase in the steady-state levels of paxillin mRNA. Stimulation with TGF-beta1 on a fibronectin substrate increased subsequent attachment and spreading of U-251MG cells onto fibronectin and, to a lesser extent, vitronectin, but not collagen. Our results indicate that physiologic levels of TGF-beta1 stimulate the expression of paxillin protein at the level of translation through a process that requires engagement of the fibronectin receptor, and promotes attachment and spreading of malignant astrocytoma cells on fibronectin.

Suppressor of fused negatively regulates beta-catenin signaling

Suppressor of fused (Su(fu)) is a negative regulator of the Hedgehog signaling pathway that controls the nuclear-cytoplasmic distribution of Gli/Ci transcription factors through direct protein-protein interactions. We show here that Su(fu) is present in a complex with the oncogenic transcriptional activator beta-catenin and functions as a negative regulator of T-cell factor (Tcf)-dependent transcription. Overexpression of Su(fu) in SW480 (APC(mut)) colon cancer cells in which beta-catenin protein is stabilized leads to a reduction in nuclear beta-catenin levels and in Tcf-dependent transcription. This effect of Su(fu) overexpression can be blocked by treatment of these cells with leptomycin B, a specific inhibitor of CRM1-mediated nuclear export. Overexpression of Su(fu) suppresses growth of SW480 (APC(mut)) tumor cells in nude mice. These observations indicate that Su(fu) negatively regulates beta-catenin signaling and that CRM-1-mediated nuclear export plays a role in this regulation. Our results also suggest that Su(fu) acts as a tumor suppressor.

[Analysis on the surveillanca data of newborn death from 1990 to 1999 in Rugao City, Jiangsu province]

A surveillance and data analysis on the cause and death rate of newborn death in Rugao city, Jiangsu Provinces was conducted from 1990 to 1999. There were 1300 cases died in these 10 years. The mortality rate was 0.92% and the proportion of male to female was 1.53:1. More cases (75%) were died in the early stage after birth. The causes of the newborn death were in the order of premature, asphyxia, pneumonia, congenital anomaly and accidental asphyxia. More babies (75.62%) were died in hospitals. The emphasis on newborn health care was pointed out and had discussions. Taking comprehensive measures would be the key point to reduce newborn mortality rate.

Proteasomes and proteasome inhibition in the central nervous system

Although the proteasome is responsible for the majority of intracellular protein degradation, and has been demonstrated to play a pivotal role in a diverse array of cellular activities, the role of the proteasome in the central nervous system is only beginning to be elucidated. Recent studies have demonstrated that proteasome inhibition occurs in numerous neurodegenerative conditions, and that proteasome inhibition is sufficient to induce neuron death, elevate intracellular levels of protein oxidation, and increase neural vulnerability to subsequent injury. The focus of this review is to describe what is currently known about proteasome biology in the central nervous system and to discuss the possible role of proteasome inhibition in the neurodegenerative process.

Proteasome inhibition in oxidative stress neurotoxicity: implications for heat shock proteins

Recent studies have demonstrated that inhibition of the proteasome, an enzyme responsible for the majority of intracellular proteolysis, may contribute to the toxicity associated with oxidative stress. In the present study we demonstrate that exposure to oxidative injury (paraquat, H(2)O(2), FeSO(4)) induces a rapid increase in reactive oxygen species (ROS), loss of mitochondrial membrane potential, inhibition of proteasome activity, and induction of cell death in neural SH-SY5Y cells. Application of proteasome inhibitors (MG115, epoxomycin) mimicked the effects of oxidative stressors on mitochondrial membrane potential and cell viability, and increased vulnerability to oxidative injury. Neural SH-SY5Y cells stably transfected with human HDJ-1, a member of the heat shock protein family, were more resistant to the cytotoxicity associated with oxidative stressors. Cells expressing increased levels of HDJ-1 displayed similar degrees of ROS formation following oxidative stressors, but demonstrated a greater preservation of mitochondrial function and proteasomal activity following oxidative injury. Cells transfected with HDJ-1 were also more resistant to the toxicity associated with proteasome inhibitor application. These data support a possible role for proteasome inhibition in the toxicity of oxidative stress, and suggest heat shock proteins may confer resistance to oxidative stress, by preserving proteasome function and attenuating the toxicity of proteasome inhibition.

Alterations of MAPK activities associated with intestinal cell differentiation

Three distinct groups of mitogen-activated protein kinases (MAPKs) have been identified in mammalian cells (i.e., ERK, JNK, and p38) which play an important role in the differentiation and apoptosis of various cells. The purpose of our present study was to determine MAPK activity and levels associated with sodium butyrate (NaBT)-mediated differentiation and apoptosis in the human colon cancer cell lines Caco-2 and HT29. Intestinal alkaline phosphatase (IAP) activity, a marker of intestinal differentiation, was increased at 48 h after NaBT treatment followed by cell death at 72 h. ERK activity was decreased in differentiated Caco-2 cells either induced with NaBT or allowed to differentiate spontaneously and in HT29 cells treated with NaBT. The combination of the MEK inhibitor, PD98059, with NaBT further increased IAP activity and cell death compared with NaBT alone. In contrast to ERK, JNK1 activity and c-Jun phosphorylation was increased 8 h after NaBT treatment suggesting a role for the JNK pathway in intestinal cell differentiation and apoptosis. p38 activity was increased at 24 and 48 h after NaBT treatment. Taken together, our results suggest that alterations in MAPKs (i.e., ERK inhibition and JNK induction) contribute to the differentiation and apoptotic pathways in intestinal cells.