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The mouse PDGF β-receptor promoter is tightly controlled by NF-Y that binds to a CCAAT box located upstream of the initiation site [1, 2]. In this report, we show that Sp1 plays an essential role in the PDGF β-receptor transcription. Within the upstream GC rich area there are two Sp1 binding sites located in close proximity to the CCAAT box. Deletion of the GC rich region resulted in a 50% decrease of the transcriptional activity of the promoter, and a complete loss of its responsiveness to over-expression of Sp1. There was an additive effect between NF-Y and Sp1 in reporter activity when they were co-transfected together with the promoter-reporter construct. Furthermore, transfection of NF-Y failed to enhance transcriptional activity when the Sp1 binding sites were deleted from the promoter, suggesting an important role for Sp1 in this NF-Y controlled transcription. We have recently reported that c-Myc represses PDGF β-receptor transcription through its interference with the transactivation activity of NF-Y [3]. In the case of p21waf1/cip1 transcription, c-Myc was shown to repress its transcription by sequestering Sp1 [4]. However, we could not find any effect of Sp1 in the c-Myc-mediated repression on the PDGF β-receptor promoter, since the deletion of Sp1 binding sites could not attenuate the repression by c-Myc on the promoter activity.

The aim of the present study is to clarify in situ expression of platelet-derived growth factor (PDGF) and its receptors in different phases of inflammatory bowel disease (IBD). Tissues samples were obtained from 20 patients with ulcerative colitis (UC) and 29 with Crohn's disease (CD) at surgery. In situ hybridization and immunohistochemistry on frozen sections were performed for PDGF-A and -B and its alpha and beta receptors (alphaR and betaR). The area of active inflammation was infiltrated by abundant polymorphonuclear and mononuclear leukocytes, of which the latter expressed mRNA and proteins of PDGF-A, -B, and -alphaR and mRNA for PDGF-betaR. The area of active fibrosis, characterized by activated fibroblasts/ myofibroblasts, was juxtaposed to ulceration, which is induced as a repair process to tissue destruction. In these areas, activated fibroblasts/myofibroblasts were positive for mRNA and protein of PDGF-A, -B, -alphaR, and -betaR. The expression of PDGF-A, -B, and -alphaR declined significantly in the scar area. Our results suggest that PDGF is not only important as an inducer of fibrosis in the repair phase but also it is involved in the active inflammatory phase possibly as a chemoattractant for mononuclear inflammatory cells.

PDGF and TNF-alpha are both known to play important roles in inflammation, albeit frequently by opposing actions. Typically, TNF-alpha can attenuate PDGF beta-receptor signaling. Pretreatment of mouse 3T3 L1 fibroblasts with TNF-alpha greatly diminished their proliferative response to PDGF. However, TNF-alpha affected neither the binding of PDGF-BB to cell surface receptors nor the total amount of PDGF beta-receptor in the cells, but decreased the PDGF-induced in vitro kinase activity of the receptor. The phosphatase inhibitor ortho-vanadate did not prevent this effect. Ortho-phosphate labeling of cells prior to TNF-alpha treatment and PDGF-BB stimulation confirmed a decrease of in vivo phosphorylation of the PDGF beta-receptor. Two-dimensional mapping after tryptic cleavage as well as phosphoamino acid analysis demonstrated a general decrease in phosphorylation of all known tyrosine residues in the PDGF beta-receptor. The exact mechanism for this suppression remains to be clarified (Less)

Vascular endothelial growth factor (VEGF) is a known endothelial mitogen and a potent enhancer of vascular permeability although its role in focal cerebral ischemia is still not completely understood. The present report describes the immunohistochemical distribution of VEGF and its 2 receptors, Flt-1 and Flk-1 at day 1 and 3 following permanent and transient middle cerebral artery occlusion (MCAO) in the rat. A bilateral increase in VEGF immunoreactivity, particularly in neurons and blood vessels, was seen in both the experimental designs by day 1. By day 3, the immunoreactivity was restricted chiefly to the lesion side, where reaction was most prominent in the border zones of the infarcts. Immunoreaction to VEGF was more pronounced in cases of permanent MCAO than in transient MCAO. Flt-1 reaction was increased in neurons, glial and endothelial cells after both transient and permanent MCAO. Immunoreactivity to Flk-1 was prominent in glial cells and was present to some extent in endothelial cells. These findings indicate an early upregulation of VEGF and its receptors after permanent as well as transient focal cerebral ischemia in the rat.

Transforming growth factor-beta (TGF-beta) and bone morphogenetic proteins (BMPs) signal via distinct type I and type II receptors and Smad proteins. A nine amino acid sequence between kinase subdomains IV and V in type I receptors, termed the L45 loop, has been shown to be important in conferring signalling specificity. We examined the responses of a mutant TGF-beta type I receptor (TbetaR-I) and a mutant BMPR-IB, in which the L45 regions of these two receptors were exchanged. Swapping the four amino acid residues that are different in BMPR-IB for those in TbetaR-I, and vice versa, switched their type I receptor-restricted Smad activation and specificity in transcriptional responses. These studies identify the L45 loop regions in type I receptors as critical determinants in specifying Smad isoform activation.

The change of phenotypic traits in domestic animals and crops as a response to selective breeding mimics the much slower evolutionary change in natural populations. Here, we describe that the dominant white phenotype in domestic pigs is caused by two mutations in theKIT gene encoding the mast/stem cell growth factor receptor (MGF), one gene duplication associated with a partially dominant phenotype and a splice mutation in one of the copies leading to the fully dominant allele. The splice mutation is a G to A substitution in the first nucleotide of intron 17 and leads to skipping of exon 17. The duplication is most likely a regulatory mutation affecting KIT expression, whereas the splice mutation is expected to cause a receptor with impaired or absent tyrosine kinase activity. Immunocytochemistry showed that this variant form is expressed in 17- to 19-day-old pig embryos. Hundreds of millions of white pigs around the world are assumed to be heterozygous or homozygous for the two mutations.[The EMBL accession numbers for porcineKIT1*0101, KIT1*0202, KIT2*0202, and KIT2*0101 areAJ223228–AJ223231, respectively.]

It is known that transforming growth factor beta (TGF-beta) is involved in the modulation of cell growth, differentiation, and repair following injury. We performed an immunohistochemical study of human brain autopsy and biopsy material for the expression of TGF-beta isoforms beta 1, beta 2 and beta 3, and TGF-beta receptor (T beta R) type I in different cells of necrotizing lesions such as infarction and abscess, and compared them with controls. Various cell types, both inside and in the proximity of lesions, showed immunoreactivity indicating the presence of all three isoforms. Significant values of immunoreaction for various TGF-beta s and T beta R-I were observed in cells such as astrocytes, macrophages, neurons, microvascular endothelial cells, and granulocytes. In the control cases, comprising biopsy material without necrotizing lesions, a prominent TGF-beta 2 immunoreactivity was observed in glial cells and neurons. TGF-beta 1 and TGF-beta 3 reactivity in controls, when compared with TGF-beta 2, was less. T beta R-I antiserum showed clear and distinct signals in the same type of cells as for TGF-beta s in the necrotizing lesions with varying values of significance. Our findings suggest that TGF-beta s and their receptor type I are involved in reactive processes around necrotizing human brain lesions like glial and macrophage responses, angiogenesis, and deposition of extracellular matrix.

Early detection and diagnosis of bipolar disorder can be difficult. Tools are needed to help clinicians detect bipolar disorder earlier, which would ameliorate the prognosis.ELISA kits that distinguish between mature brain derived neurotrophic factor (BDNF) and proBDNF, we compared serum levels of mature BDNF, proBDNF, and matrix metalloproteinase-9 (MMP-9) in two independent cohorts (Sahlgrenska cohort and Karolinska cohort) of mood-stabilized bipolar patients and healthy controls. The total sample size in both cohorts consisted of 263 (48+215) bipolar patients and 155 (43+112) healthy controls.Levels of mature BDNF and the ratio mature BDNF/proBDNF were significantly higher in patients than in controls. Serum levels of proBDNF were significantly lower in patients compared to controls. Serum levels of MMP-9 did not differ between the groups but MMP-9 correlated positively and significantly with mature BDNF. Mature BDNF, proBDNF, the ratio of mature BDNF/proBDNF and interactions with MMP-9 explained the diagnostic dichotomy in both cohorts with high significance, using multivariate logistic ANCOVA (gender, age, and BMI were covaried out). The model explained 41% of the diagnostic variance in the Sahlgrenska cohort (p0.0001) and 15% in the Karolinska cohort (p0.0001). In both cohorts, the equations provided good power for diagnostic classification. The diagnostic sensitivity was 89% in the Sahlgrenska and 74% in the Karolinska cohort, and specificity 77% and 64%, respectively.The study is cross-sectional with no longitudinal follow up. The cohorts are relatively small with no medication-free patients. There are no "ill patient controls".Abnormalities in the conversion of proBDNF to mature BDNF may be associated with pathogenesis of bipolar disorder. Clinical use of these biomarkers may provide opportunities for earlier detection and correct treatment.

Rats transplanted with the androgen-sensitive Dunning R3327 PAP prostatic adenocarcinoma were castrated and treated with either estrogen or vehicle alone for short periods (4 hr, 12 hr, 24 hr) and for 6 weeks. In these tumors the expression of TGF-beta 1, TGF-beta type-I and type-II receptors (TGF-beta RI, TGF-beta RII) was examined by immunohistochemistry. Apoptotic cells were identified by in situ nick and labelling (TUNEL). Tumor growth was retarded by castration and even more by additive estrogen treatment. The epithelium of the untreated tumors stained weakly for TGF-beta 1 and TGF-beta RI, but TGF-beta RII was not detected. Castration induced moderate TGF-beta 1 immunoreactivity in a major part of the glandular epithelium after 24 hr. After 12 hr already, castration plus estrogen resulted in an intense staining for TGF-beta 1 in the basal epithelial cells, some of which also showed an apoptotic appearance. The percentage of cells having stained positive for TGF-beta 1 was significantly higher in the estrogen-treated groups than in the castrated group after 12 hr, and its elevated TGF-beta 1 level remained at 6 weeks. Notably, the increased immunoexpression of TGF-beta 1 occurred before the onset of induction of apoptosis. In parallel with the upregulation of TGF-beta 1 after castration, the expression of its receptors. TGF-beta RI and RII, was induced and was further enhanced by the additive estrogen treatment. The number of intensely stained TGF-beta 1 tumor cells showed a strong correlation with the number of apoptotic tumor cells identified by TUNEL in the whole material. Furthermore, TGF-beta 1 immunoreactivity co-localized with the presence of apoptotic cells in the estrogen-treated tumors at 6 weeks after castration.

The kinetics of platelet-derived growth factor messenger RNA synthesis in the substantia nigra and in the striatum, before and after unilateral intranigral 6-hydroxydopamine injection, was studied and compared with that after sham operation by a quantitative reverse transcription–polymerase chain reaction. The kinetics of brain-derived neurotrophic factor messenger RNA was studied as a comparison. Furthermore, the expression of platelet-derived growth factor A- and B-chain proteins was analysed by enzyme-linked immunosorbent assay and immunohistochemistry. In the ipsilateral striatum of 6-hydroxydopamine-lesioned rats, the signal density of messenger RNA for both A- and B-chains had already increased at one day and remained at an elevated level during the observation period of four weeks. In the substantia nigra ipsilateral to the lesion, a strongly increased level of B-chain and, to a lesser extent, of A-chain messenger RNA was already detected at 4 h, reaching a maximal level at one day. No significant increase was seen either in sham-operated rats or in the contralateral striatum and substantia nigra. Amounts of platelet-derived growth factor proteins were examined separately by enzyme-linked immunosorbent assay in both sides of the substantia nigra, striatum and cortex. Three days after 6-hydroxydopamine lesions the levels of both platelet-derived growth factor A- and B-chains increased in the ipsilateral striatum, substantia nigra, and cortex. An increase in the A-chain was also observed in the contralateral side of the brain. The signal for brain-derived neurotrophic factor messenger RNA increased in the striatum in the lesioned side and, to a lesser extent, in the contralateral side, as well as the in the substantia nigra, where a significant difference was observed when compared with the contralateral side. Semiquantitative immunohistochemical analysis on the substantia nigra confirmed the enhanced platelet-derived growth factor expression, revealing that the majority of the platelet-derived growth factor-producing cells were neurons. In summary, we have shown that platelet-derived growth factor messenger RNA as well as its protein are induced after injury to dopaminergic cells. These data indicate an important role of platelet-derived growth factor in the dopaminergic system.

The localization and production at the single cell level of 19 different human cytokines, IL-1 alpha, IL-1 beta, IL-1ra, IL-2, IL-3, IL-4, IL-5, IL-6, IL-8, IL-10, IL-13, TNF alpha, TNF beta, IFN gamma, GM-CSF, G-CSF, and TGF beta 1-3, were studied in cryopreserved tonsillar tissue using immunohistochemical staining. The cytokine producing cells, with the exception of IL-1 expressing cells, had a characteristic morphology due to the accumulation of cytokine onto the Golgi organelle. The production of each cytokine was localized to specific compartments in tonsillar tissue sections from children with tonsillar hypertrophy or recurrent tonsillitis in the resting state. Immunoregulatory cytokines such as IL-2, IL-3, IL-4, G-CSF, GM-CSF and TGF beta were produced in the extrafollicular area and entrapped on the cell membranes as well as in pudels in the extracellular matrix surrounding the producer cells. The dominating cytokines both in tissues from recurrent tonsillitis and tonsillar hypertrophy were GM-CSF, G-CSF, and TGF beta 1-3 which were synthezised predominantly in the reticular crypt site. IL-1 alpha, beta and IL-1ra, on the other hand, were localized to the surface and crypt epithelium and to scattered regions in the extrafollicular area. IL-2, IL-6, IFN gamma and IL-10 were found much more often in sections obtained from recurrent tonsillitis tissue compared with those from tonsillar hypertrophy. Reversely, an excessive production of IL-4 was noted in tonsillar hypertrophy compared with that in recurrent tonsillitis. Thus, concomitant production of multiple cytokines was evident with similarities but also differences in cytokine pattern between the two groups studied. The data suggest that T-cell mediated B-cell activation and differentiation take place in the extrafollicular area. Children with recurrent tonsillitis had a higher amount of B-cells and monocytes compared with children with tonsillar hypertrophy. However, the number of CD3, CD4, CD8 or cytoplasmic Ig-positive cells did not differ between the two groups.

The distribution of bone morphogenetic protein (BMP) type I receptors and the activin type I receptor (ActR-I) was investigated in 16 cases of human glioma and five cases of non-tumourous gliosis tissue by immunohistochemical technique. Both BMP type IA (BMPR-IA) and the type IB (BMPR-IB) receptors were detected in human glioma cells. A significant increase in BMPR-IB in tumour cells was observed in malignant glioma compared with both low-grade astrocytomas (n=16, P

We have examined the effects of either brain-derived neurotrophic factor (BDNF), the BB-isoform of platelet-derived growth factor (PDGF-BB), or a combination of these growth factors on the survival and the morphological development of embryonic striatal neurons grown under serum-free culture conditions. Striatal neurons were identified using immunocytochemistry for "dopamine- and adenosine 3':5'-monophosphate-regulated phosphoprotein with a molecular weight of 32 kilodalton" (DARPP-32). BDNF and PDGF-BB promoted the survival of DARPP-32-positive neurons, with the magnitude of their effects being comparable. A combination of these growth factors exerted no significant additive effects on cell survival. BDNF stimulated morphological differentiation of DARPP-32-containing neurons by increasing the length of neurites, the number of branching points on the neurites, and the soma area. By contrast, PDGF-BB increased the neurite length and the cell body area, but not the number of branching points. BDNF also protected striatal neurons from excitotoxicity induced by N-methyl-D-aspartate, whereas PDGF-BB had no effect under the same treatment conditions as those for BDNF. Thus, BDNF is trophic for striatal DARPP-32-containing neurons in vitro by enhancing the survival, morphological differentiation and resistance to excitotoxicity, and its mechanisms of action are probably different from those of PDGF-BB.

Immunohistochemical studies of transforming growth factor-beta (TGF-beta) and its receptors have been carried out on 16 glioma tissues and compared with 5 cases of gliosis. Significantly higher expressions of TGF-beta I, as well as type-I and type-II TGF-beta receptors (T beta R-I and T beta R-II, respectively), were observed in advanced-malignant-glioma tissues when compared with non-tumorous gliosis. Immunoreactivities of TGF-beta and T beta R-I were localized in the cytoplasm of spindle-shaped tumor cells surrounding proliferating vessels or around areas of necrosis. The advancing edge of the tumor clusters frequently stained positive. Similar expression patterns were found for TGF-beta 2 and TGF-beta 3, whereas only weak or no expression was found for endoglin. In low-grade astrocytomas and in gliosis cases, the expression was moderate for T beta R-I and weak for TGF-beta and T beta R-II. In 3 examined human malignant glioma cell lines, clear immunostainings were detected for TGF-beta and its receptors. Ligand-induced heteromeric complexes of the receptors were formed in these cell lines, but the amount of the receptors was less than that of mink lung epithelial cells, which are sensitive target cells for TGF-beta. TGF-beta I showed no growth-inhibitory activity on any of these glioma cell lines. These results suggest that malignant gliomas produce TGF-beta and receptors, but are refractory to TGF-beta, implying dysregulation in the signalling pathway in the tumor cells. It is possible that the released TGF-beta acts on neighboring cells and affects stromal growth, angiogenesis, metastasis or immune surveillance in human glioma.

The effects of low molecular weight heparin derivatives with a low anticoagulant activity on transplant arteriosclerosis (TA) in a rat aortic transplant model were investigated. TA was induced by i ...

Adhesion molecules play a crucial role in transplant rejection in regulating the interaction of inflammatory cells with cells in the vascular wall. In an aortic transplantation model, we have previously analysed the early adhesion process (7.5 min to 24 h) and the impact of cold ischaemia time (1-24 h) upon transplant arteriosclerosis during the first 2 months after transplantation in the rat. The aim of this investigation was to study adhesion molecules in accelerated transplant arteriosclerosis in a rat model by analysing the immunohistochemical expression of CD11b and ICAM-1 up to 2 months and followed by a semiquantitative evaluation and multivariant analysis. Antigen expression of CD11b and ICAM-1 adhesion molecules was stronger in the aortic allografts than in the ischaemia-induced syngeneic aortic grafts in the whole vessel wall. Neither ICAM-1 nor CD11b antigen expression correlated significantly with time periods of ischaemia/reperfusion injury in allogeneic or syngeneic aortic transplants. CD11b and ICAM-1 are induced by allogeneic stimuli in transplanted aortas suggesting a role in the pathogenesis of transplant arteriosclerosis. Our findings have implications for understanding the role of cell adhesion activation in the vascular wall subject to chronic graft rejection.

The influence of the somatostatin analogue angiopeptin on transplant arteriosclerosis was investigated using two aortic transplantation rat models. One was characterized by ischemia/reperfusion-induced changes in syngeneic transplants while immunologically induced changes dominated in the other allogeneic model. Angiopeptin, 100 micrograms/kg per day, was administered continuously until the sacrifice of the rats after 8 weeks. No additional immunosuppression was used in either model. An image analysis system was used to quantify the intimal and medial thicknesses of the grafts. In the syngeneic grafts, the intimal thickness was less than 50% of that of control grafts (P0.05), but no difference was seen in the allogeneic model. The expression of selected cells, TGF-beta s, and PDGF and PDGF alpha-receptors was detected immunohistochemically and displayed a similar picture in control and angiopeptin-treated grafts in both models. We conclude that angiopeptin has no clear immunosuppressive properties but may counteract ischemia-induced transplant arteriosclerosis.

Activation of neural stem/progenitor cells (NSPCs) is a potential therapeutic strategy of neurological disorders. In this study, NSPCs of subventricular zone were isolated and cultured from platelet-derived growth factor-β-receptor-knockout (PDGFR-β(-/-)) mice of postnatal day 1 (P1) and P28, and the roles of PDGFR-β were examined in these cells. In PDGFR-β-preserving control NSPCs, stem cell activities, such as numbers and diameters of secondary neurospheres, cell proliferation and survival rates, were significantly higher in P1 NSPCs than those in P28 NSPCs. In PDGFR-β(-/-) NSPCs, most of these parameters were decreased as compared with age-matched controls. Among them, the decrease of secondary neurosphere formation was most striking in P1 and P28 PDGFR-β(-/-) NSPCs and in P28 control NSPCs as compared with P1 control NSPCs. PCR-array and following quantitative real-time PCR (qRT-PCR) analyses demonstrated that expressions of fibroblast growth factor-2 (FGF2) and exons IV-IX of brain-derived neurotrophic factor (BDNF) were decreased, and noggin was increased in P1 PDGFR-β(-/-) as compared with P1 controls. Addition of BDNF rescued the number and diameter of secondary neurospheres in P1 PDGFR-β(-/-) NSPCs to similar levels as controls. The expressions of PDGFs and PDGFRs in control NSPCs were increased along with the differentiation-induction, where phosphorylated PDGFR-β was co-localized with neuronal and astrocyte differentiation markers. In controls, the neuronal differentiation was decreased, and the glial differentiation was increased from P1 to P28 NSPCs. Compared with P1 controls, neuronal differentiation was reduced in P1 PDGFR-β(-/-) NSPCs, whereas glial differentiation was comparable between the two genotypes. These results suggest that PDGFR-β signaling is important for the self-renewal and multipotency of NSPCs, particularly in neonatal NSPCs. BDNF, FGF2, and noggin may be involved in the effects of PDGFR-β signaling in these cells. Accordingly, the activation of PDGFR-β in NSPCs may be a novel therapeutic strategy of neurological diseases.

The objective of the present study was to determine if either of the two isoforms of platelet-derived growth factor (PDGF), PDGF-AA and PDGF-BB, exerts trophic effects in vitro on developing rat striatal neurons. Striatal neurons were identified using immunocytochemistry for dopamine- and adenosine 3':5'-monophosphate-regulated phosphoprotein with a molecular weight of 32 kilodalton (DARPP-32). In control cultures without PDGF, the mean number of DARPP-32-positive neurons decreased by 47% at days 3 to 5 in vitro. PDGF-BB, but not PDGF-AA, significantly increased the number of DARPP-32-positive neurons both at day 3 (by 42%) and day 5 (by 149%). Total cell number was similar in control and PDGF BB-treated cultures, suggesting that, in striatal cultures, the action of PDGF-BB is relatively specific for DARPP-32-positive neurons. The DARPP-32-positive neurons in PDGF-BB-treated cultures had longer neurites and larger soma areas than those in control and in PDGF-AA-treated cultures. Our data provide evidence that PDGF-BB exerts a trophic action on striatal DARPP-32-positive neurons in vitro by promoting cell survival and morphological differentiation, although a stimulatory effect on intraneuronal DARPP-32 levels also is possible. The findings raise the possibility that PDGF-BB might also be involved in the development and maintenance of striatal neurons in vivo, and could be used to counteract striatal degeneration in models of Huntington's disease.

microRNAs (miRNAs) spatio-temporally modulate gene expression; however, very little is known about the regulation of their expression. Here, we hypothesized that the well-known cis-regulatory elements of gene expression, scaffold/matrix-attachment regions (MARs) could modulate miRNA expression. Accordingly, we found MARs to be enriched in the upstream regions of miRNA genes. To determine their role in cell type-specific expression of miRNAs, we examined four individual miRNAs (let-7b, miR-17, miR-93 and miR-221) and the miR-17–92 cluster, known to be overexpressed in neuroblastoma. Our results show that MARs indeed define the cell-specific expression of these miRNAs by tethering the chromatin to nuclear matrix. This is brought about by cell type-specific binding of HMG I/Y protein to MARs that then promotes the local acetylation of histones, serving as boundary elements for gene activation. The binding, chromatin tethering and gene activation by HMG I/Y was not observed in fibroblast control cells but were restricted to neuroblastoma cells. This study implies that the association of MAR binding proteins to MARs could dictate the tissue/context specific regulation of miRNA genes by serving as a boundary element signaling the transcriptional activation.

DNA copy number aberrations (CNAs) are a characteristic feature of cancer genomes. In this work, Rebecka Jörnsten, Sven Nelander and colleagues combine network modeling and experimental methods to analyze the systems-level effects of CNAs in glioblastoma., We introduce a modeling approach termed EPoC (Endogenous Perturbation analysis of Cancer), enabling the construction of global, gene-level models that causally connect gene copy number with expression in glioblastoma. On the basis of the resulting model, we predict genes that are likely to be disease-driving and validate selected predictions experimentally. We also demonstrate that further analysis of the network model by sparse singular value decomposition allows stratification of patients with glioblastoma into short-term and long-term survivors, introducing decomposed network models as a useful principle for biomarker discovery. Finally, in systematic comparisons, we demonstrate that EPoC is computationally efficient and yields more consistent results than mRNA-only methods, standard eQTL methods, and two recent multivariate methods for genotype–mRNA coupling., Gains and losses of chromosomal material (DNA copy number aberrations; CNAs) are a characteristic feature of cancer genomes. At the level of a single locus, it is well known that increased copy number (gene amplification) typically leads to increased gene expression, whereas decreased copy number (gene deletion) leads to decreased gene expression (Pollack et al, 2002; Lee et al, 2008; Nilsson et al, 2008). However, CNAs also affect the expression of genes located outside the amplified/deleted region itself via indirect mechanisms. To fully understand the action of CNAs, it is therefore necessary to analyze their action in a network context. Toward this goal, improved computational approaches will be important, if not essential. To determine the global effects on transcription of CNAs in the brain tumor glioblastoma, we develop EPoC (Endogenous Perturbation analysis of Cancer), a computational technique capable of inferring sparse, causal network models by combining genome-wide, paired CNA- and mRNA-level data. EPoC aims to detect disease-driving copy number aberrations and their effect on target mRNA expression, and stratify patients into long-term and short-term survivors. Technically, EPoC relates CNA perturbations to mRNA responses by matrix equations, derived from a steady-state approximation of the transcriptional network. Patient prognostic scores are obtained from singular value decompositions of the network matrix. The models are constructed by solving a large-scale, regularized regression problem. We apply EPoC to glioblastoma data from The Cancer Genome Atlas (TCGA) consortium (186 patients). The identified CNA-driven network comprises 10 672 genes, and contains a number of copy number-altered genes that control multiple downstream genes. Highly connected hub genes include well-known oncogenes and tumor supressor genes that are frequently deleted or amplified in glioblastoma, including EGFR, PDGFRA, CDKN2A and CDKN2B, confirming a clear association between these aberrations and transcriptional variability of these brain tumors. In addition, we identify a number of hub genes that have previously not been associated with glioblastoma, including interferon alpha 1 (IFNA1), myeloid/lymphoid or mixed-lineage leukemia translocated to 10 (MLLT10, a well-known leukemia gene), glutamate decarboxylase 2 GAD2, a postulated glutamate receptor GPR158 and Necdin (NDN). Furthermore, we demonstrate that the network model contains useful information on downstream target genes (including stem cell regulators), and possible drug targets. We proceed to explore the validity of a small network region experimentally. Introducing experimental perturbations of NDN and other targets in four glioblastoma cell lines (T98G, U-87MG, U-343MG and U-373MG), we confirm several predicted mechanisms. We also demonstrate that the TCGA glioblastoma patients can be stratified into long-term and short-term survivors, using our proposed prognostic scores derived from a singular vector decomposition of the network model. Finally, we compare EPoC to existing methods for mRNA networks analysis and expression quantitative locus methods, and demonstrate that EPoC produces more consistent models between technically independent glioblastoma data sets, and that the EPoC models exhibit better overlap with known protein–protein interaction networks and pathway maps. In summary, we conclude that large-scale integrative modeling reveals mechanistically and prognostically informative networks in human glioblastoma. Our approach operates at the gene level and our data support that individual hub genes can be identified in practice. Very large aberrations, however, cannot be fully resolved by the current modeling strategy., DNA copy number aberrations (CNAs) are a hallmark of cancer genomes. However, little is known about how such changes affect global gene expression. We develop a modeling framework, EPoC (Endogenous Perturbation analysis of Cancer), to (1) detect disease-driving CNAs and their effect on target mRNA expression, and to (2) stratify cancer patients into long- and short-term survivors. Our method constructs causal network models of gene expression by combining genome-wide DNA- and RNA-level data. Prognostic scores are obtained from a singular value decomposition of the networks. By applying EPoC to glioblastoma data from The Cancer Genome Atlas consortium, we demonstrate that the resulting network models contain known disease-relevant hub genes, reveal interesting candidate hubs, and uncover predictors of patient survival. Targeted validations in four glioblastoma cell lines support selected predictions, and implicate the p53-interacting protein Necdin in suppressing glioblastoma cell growth. We conclude that large-scale network modeling of the effects of CNAs on gene expression may provide insights into the biology of human cancer. Free software in MATLAB and R is provided.

Trophic effects of platelet-derived growth factor -AA and -BB on developing (embryonic day 14) ventral mesencephalon were studied using the in vivo model of intraocular transplantation to sympathetically denervated host eyes. This model enabled studies of survival and growth of grafted brain tissue, dopaminergic fiber outgrowth from the grafts onto the host iris as well as morphological effects of platelet-derived growth factor on grafted tissue using markers for tyrosine hydroxylase and glial fibrillary acid protein. Growth of grafts was followed by repeated observations directly through the cornea of the host using a stereomicroscope. This revealed that there was no apparent effect on volume increase of mesencephalic grafts after treatments with either platelet-derived growth factor-AA (100 ng/ml buffer), platelet-derived growth factor-BB (100 ng/ml buffer) or vehicle solution (high salt buffer) alone. Growth factor treatments were administered immediately prior to grafting by incubating the grafts in the appropriate factor as well as on days 5, 10 and 15 postgrafting by administration of 5-microliters intraocular injections of similar solutions as used for incubation. Platelet-derived growth factor-AA significantly enhanced dopaminergic fiber outgrowth from mesencephalic grafts when compared to both platelet-derived growth factor-BB and controls, without an accompanying rise in the number of tyrosine hydroxylase-positive neurons. In contrast, a significantly greater number of tyrosine hydroxylase-positive neurons was seen in grafts treated with platelet-derived growth factor-BB but without an accompanying increase in outgrowth of dopamine-containing fibers.(ABSTRACT TRUNCATED AT 250 WORDS)

Platelet-derived growth factor (PDGF) is a well known mitogen for mesenchyme-derived cells and glial cells. Its presence in neuronal cells of the central nervous system has only recently been described. We have shown earlier that neurons of newborn rat brains in culture express PDGF β-receptors and that PDGF-BB, a homodimer of PDGF B-chain, increases survival and promotes neurite outgrowth of newborn cerebellar cells (Smits et al., Proc. Natl Acad. Sci. USA, 88, 8159 – 8163, 1991). In this study, the effects of PDGF on early postnatal rat cerebellar cells were further explored. By using chemically defined serum-free medium, we have established primary cell cultures of rat cerebella (postnatal day 4 – 5) containing 70 – 80% neuronal cells. During the first 10 days in vitro, no difference in total cell number was found between PDGF-BB-treated and untreated cultures. After this time period, however, increased survival of the PDGF-BB-treated cells was found. Within the first 10 days in vitro, the addition of PDGF-BB to the cultures resulted in a relative increase in survival of interneurons expressing glutamic acid decarboxylase (GAD), the GABA biosynthetic enzyme. Moreover, addition of PDGF-BB in the untreated cell culture resulted in a rapid increase of GAD mRNA. These results show that PDGF-BB acts as a trophic factor on GABAergic interneurons of the cerebellum by up-regulating GAD synthesis and prolonging the survival of these cells. Furthermore, in situ hybridization revealed that there are scattered cells present in the early postnatal cerebellum that express PDGF β-receptor mRNA. The localization of these cells in the molecular layer and in the proximity of the internal granular layer corresponds to that of GABAergic interneurons in the developing cerebellum.

There is increasing evidence to suggest that platelet-derived growth factor (PDGF) or PDGF-like molecules play a role in fetal lung morphogenesis. Our previous studies demonstrated that fetal lung epithelial cells respond mitogenically to exogenous PDGF, while fetal lung fibroblasts respond with increased glycosaminoglycan synthesis. To further study the target cells of PDGF in fetal rat lung, we investigated the presence and nature of PDGF receptors in fetal lung cells. Functional PDGF receptors were expressed on normal epithelial cells of fetal rat lung. All three isoforms of PDGF (AA, AB, and BB) were mitogenic for quiescent epithelial cells. Northern blot and protein analysis demonstrated the presence of PDGF alpha-receptor and PDGF beta-receptor. All isoforms of PDGF enhanced tyrosine kinase activity and stimulated receptor autophosphorylation. In contrast, fetal lung fibroblasts expressed only the PDGF beta-receptor. PDGF-AB and PDGF-BB, but not PDGF-AA, stimulated tyrosine kinase activity. No PDGF isoform was mitogenic for quiescent fibroblasts. However, PDGF-BB stimulated fibroblast proliferation on a collagen type I substratum in the presence of transferrin. Binding experiments with [125I]PDGF-AA and [125I]-PDGF-BB to epithelial cells and fibroblasts confirmed these observations.

Platelet-derived growth factor (PDGF) is a pleiotropic protein with critical roles in both developmental as well as pathogenic processes. In the central nervous system specifically, PDGF is critical for neuronal proliferation and differentiation and has also been implicated as a neuroprotective agent. Whether PDGF also plays a role in synaptic plasticity, however, remains poorly understood. In the present study we demonstrated that in the rat hippocampal neurons PDGF regulated the expression of Arc/Arg3.1 gene that has been implicated in both synapse plasticity and long term potentiation. Relevance of these findings was further confirmed in vivo by injecting mice with intracerebral inoculations of PDGF, which resulted in a rapid induction of Arc in the hippocampus of the injected mice. PDGF induced long term potentiation in rat hippocampal slices, which was abolished by PDGF receptor-tyrosine kinase inhibitor STI-571. We also present evidence that PDGF-mediated induction of Arc/Arg3.1 involved activation of the MAPK/ERK (MEK) pathway. Additionally, induction of Arc/Arg3.1 also involved the upstream release of intracellular calcium stores, an effect that could be blocked by thapsigargin but not by EGTA. Pharmacological approach using inhibitors specific for either MAPK/ERK phosphorylation or calcium release demonstrated that the two pathways converged downstream at a common point involving activation of the immediate early gene Egr-1. Chromatin immunoprecipitation assays demonstrated the binding of Egr-1, but not Egr-3, to the Arc promoter. These findings for the first time, thus, suggest an additional role of PDGF, that of induction of Arc.

We have previously characterized how p53 family proteins control the transcriptional regulation of the platelet-derived growth factor β-receptor (PDGFRB) and found that ΔNp73α, acting dominant-negatively to p53 and p73, can upregulate PDGFRB promoter activity. Here, we report that PDGFRB regulation differs between two neuroblastoma cell lines, correlating with the actions of ΔNp73. We found that PDGFRB was highly expressed in IMR-32 cells, and serum stimulation of IMR-32 cells did not downregulate PDGFRB expression, as seen in SH-SY5Y cells. In IMR-32, ΔNp73 was found constitutively bound to the PDGFRB promoter, and silencing of ΔNp73 resulted in repression of PDGFRB promoter activity as well as decreased PDGFRB protein expression. However, the anticancer drug cisplatin, known to stabilize and activate p53 and p73, downregulated PDGFRB expression not only in SH-SY5Y but also in IMR-32. Chromatin immunoprecipitation showed that cisplatin removed ΔNp73 from the PDGFRB promoter and recruited p53 and p73, leading to binding of histone deacetylase 4. These results suggest a direct role of ΔNp73 in the constantly enhanced PDGFRB expression seen in tumors. (Mol Cancer Res 2009;7(12):2031–9)

The different isoforms of PDGF bind with different affinities to two different receptor types. Previously, these receptors have been demonstrated mainly on mesenchymal and glial cells. We show here that PDGF beta-type receptors are present also on rat brain neurons in vivo as well as in vitro. Immunohistochemical analysis of a sequentially sectioned brain of a newborn rat revealed the presence of PDGF beta receptors in neurons throughout the central nervous system. These beta-receptor-bearing cells were shown to contain neurofilaments by double immunofluorescence staining. Furthermore, the PDGF-BB isoform bound to cells in a neuron-enriched culture from newborn rat brains and induced c-Fos protein in these cells. Continuous PDGF-BB treatment of primary rat brain cell cultures resulted in outgrowth of neurites and prolonged survival. These results indicate a neurotrophic effect of PDGF-BB.

The distribution of the mRNAs for chromogranin A and B was analyzed by in situ hybridization with 35S-labeled oligonucleotide probes in formalin-fixed paraffin-embedded carcinoid tumor tissues. All the 15 mid-gut carcinoid tumors examined contained both mRNAs for chromogranin A and B at high level in tumor cells. Sixteen of 18 bronchial carcinoid tumors but only 2 of 5 rectal carcinoid tumors expressed one or both species of chromogranin mRNAs. The same tendency was seen with the argyrophil reaction according to Grimelius where most of the mid-gut tumor cells were uniformly stained, while considerable variation in reactivity was seen in some of the bronchial and rectal carcinoid tumor cells. The sequential sections were stained with a monoclonal antibody against chromogranin A and a polyclonal antiserum which reacts with both chromogranins. The expression of the mRNA for chromogranin A on the carcinoid tumors was almost concordant with that of chromogranin B as well as with the chromogranin A protein, whereas almost all tumors stained positively with the polyclonal antibodies. Analyses of mRNA expression of chromogranin A before and after interferon therapy on 4 patients with mid-gut carcinoids indicated an inhibition at pre-translational level. In conclusion, the mRNAs for chromogranin A and B are good markers for the carcinoid tumors, especially of mid-gut origin. Fore-gut, mid-gut and rectal carcinoid tumors are different in their endocrine properties regarding the expression of the chromogranins.

In situ hybridization (ISH) is a widely used method to detect particular mRNA synthesizing cells. The method can be used to determine neuroendocrine properties of tumors by identifying the hormone and neuropeptide mRNA-producing tumor cells. Also, monitoring the production of particular mRNA under tumor progression or during certain therapies might be of prognostic value in the management of the tumor. In this paper are described methodological backgrounds and applications of the ISH method in detecting hormone and peptide mRNA in neuroendocrine tumors, especially midgut carcinoid.

Objective The pathogenesis of atherosclerosis involves inflammation and immune reactions. Low-density lipoproteins accumulate and are oxidized (oxLDL) in the arterial intima during hypercholesterolemia, leading to activation of endothelial cells, macrophages and T cells. We have previously found that severe hypercholesterolemia can induce a switch of autoimmune responses from T helper (Th)1 to Th2 effector type in atherosclerotic apoE knockout (E0) mice. The present study was performed to investigate whether Th3 immune effector responses and their inducing cytokine, transforming growth factor-β (TGF-β) are affected by hypercholesterolemia. Methods and results In E0 mice fed with high cholesterol diet and in C57BL/6J mice treated with poloxamer P-407, an agent that elevates plasma cholesterol and triglycerides, severe hypercholesterolemia led to elevated circulating TGF-β1 levels, increased TGF-β1 + CD4 + Th3 cells in lesions and spleen, and increased Th3 dependent IgG2b antibodies to oxLDL. A positive correlation was observed between plasma TGF-β1 and cholesterol levels and between plasma TGF-β1 and IgG2b anti-oxLDL. Conclusions Such elevation of TGF-β may increase the stability of plaques by inhibiting T cell responses and macrophage activation and by stimulating collagen synthesis. This new finding could be important in the regulation of immune activity, inflammation and fibrosis in the atherosclerotic plaque.

The molecular mechanisms underlying differentiation and lineage commitment in neural stem cells are just beginning to be understood, however the molecules involved in this process and their functions remain largely unknown. Here we studied the effects and downstream signals of apoptosis signal-regulating kinase 1 (ASK1) together with all-trans retinoic acid (ATRA) on neuronal differentiation in adult hippocampus-derived progenitor (AHP) cells. Following ASK1 over-expression and ATRA treatment in AHPs, a larger number of cells differentiated into neurons and the MASH1 promoter became activated. Analyzing downstream effector molecules of ASK1 or ATRA targeting the MASH1 promoter revealed that the myocyte enhancer factor 2C (MEF2C) mediated ASK1 signalling, while activation of Sp1 was involved in ATRA signalling. Chromatin immunoprecipitation assay on the promoter revealed that ASK1 induced binding of MEF2C and Ca(2+)/calmodulin-dependent kinase II to the MASH1 promoter. Taken together, ASK1 and ATRA activate MEF2C and Sp1, respectively, and up-regulate MASH1 protein expression.

PDGF acts as an autocrine and paracrine factor in certain tumors through upregulation of the PDGF beta-receptor expression. In order to elucidate the control mechanism for the receptor expression, we have isolated an enhancer from two P1 clones that together contain a 102 kb NotI region covering the entire human PDGFRB gene. They were partially digested with TspI and cloned into the PDGFRB enhancer trap vector to make a library for identification of enhancers. The digested DNA containing enhancer was identified by expression of GFP when transfected in PDGF beta-receptor expressing cells. One of the enhancer clones was further examined by making several deletion mutants in a luciferase vector. This enhancer was most active in neuroblastoma cells, IMR32 and BE2, but less active in hemangioma and in smooth muscle cell lines. Chip assay revealed that SP1, AP2, and GATA2 bound the enhancer in BE2 cells. Their interaction occurred dependently of the cell cycle and synchronously with their binding to the promoter. Transfection of GATA2 alone or with Ets, which binds adjacent to GATA, resulted in differentiation of BE2 cells in parallel with increased PDGF beta-receptor expression. Furthermore, over-expression of the PDGF beta-receptor in BE2 cells induced neurite extension.

Purpose: ΔNp73 is an isoform of the p53 homologue p73, which lacks an NH2-terminal transactivation domain and antagonizes the induction of gene expression by p53/p73. The aim of this study was to detect ΔNp73 expression in lung cancer and to evaluate the relationship between the ΔNp73 expression level and the prognosis of patients with resected lung cancer. Experimental Design: We used immunohistochemistry to analyze the protein expression of ΔNp73 in paraffin-embedded tumor samples from 132 well-characterized lung cancer patients and compared the expression level of ΔNp73, clinical variables, and survival outcome. Results: Positive expression of ΔNp73 was detected mainly in the cytoplasm of tumor cells in 77 of 132 patients (58.3%) with lung cancer. The incidence of positive expression of ΔNp73 was 52.2, 50.0, and 70.2% in patients with stage I, II, and III, respectively (P = 0.04). Positive expression of ΔNp73 was associated with gender but not associated with age, histologic type, pathological stage, pathological T status, and pathological N status. Lung cancer patients with positive ΔNp73 expression had a poorer prognosis than those with negative ΔNp73 expression. In addition, multivariate analysis of the clinicopathological characteristics of lung cancer indicated that positive expression of ΔNp73 was a significant independent factor for predicting poor prognosis (P < 0.0001, risk ratio = 3.39). Conclusions: Expression of ΔNp73 may be a useful marker for predicting poor prognosis of patients who underwent resection of lung cancer.

BACKGROUND: Neuroblastoma is derived from cells of neural crest origin and often expresses the transcription factor human achaete-scute homolog 1 (HASH1). The aim of this study was to selectively kill neuroblastoma cells by expressing the suicide gene E. coli purine nucleoside phosphorylase (PNP) under the control of the Mash1 promoter, the murine homolog of HASH1. PROCEDURE: The E. coli PNP gene regulated by the Mash1 promoter was cloned into an expression vector and transfected into neuroblastoma and non-neuroblastoma cell lines. After addition of the prodrug M2-fluoroadenine 9-beta-D-arabinofuranoside (F-araA) the cell-specific toxicity was examined. To optimize the cell specific activity, different sizes of the Mash1 promoter were analyzed in neuroblastoma cell lines and compared with the activity in non-neuroblastoma cells. RESULTS: Estimated as the percentages of CMV enhancer-promoter, the activity was significantly higher in the neuroblastoma cells, ranging from 17 to 58% when the shortest and the most active promoter was measured. The non-neuroblastoma cells yielded only 1-6% of the CMV promoter activity. When the shortest Mash1 promoter was combined with the E. coli PNP gene the cytotoxicity was 65% in the neuroblastoma cells with low cell death in the non-neuroblastoma cell lines, relative to the cytotoxicity where the E.coli PNP gene was regulated by the strong but non-specific CMV enhancer-promoter. CONCLUSIONS: We show here that the Mash1 promoter regulating the PNP gene confers a cell-type selective toxicity in neuroblastoma cell lines. These results indicate the feasibility to use the Mash1 promoter for regulating E.coli PNP expression in gene-directed enzyme prodrug therapy (GDEPT) of neuroblastoma.

Bone morphogenetic proteins (BMPs) act as growth regulators and inducers of differentiation. They transduce their signal via three different type I receptors, termed activin receptor-like kinase 2 (Alk2), Alk3, or bone morphogenetic protein receptor Ia (BMPRIa) and Alk6 or BMPRIb. Little is known about functional differences between the three type I receptors. Here, we have investigated consequences of constitutively active (ca) and dominant negative (dn) type I receptor overexpression in adult-derived hippocampal progenitor cells (AHPs). The dn receptors have a nonfunctional intracellular but functional extracellular domain. They thus trap BMPs that are endogenously produced by AHPs. We found that effects obtained by overexpression of dnAlk2 and dnAlk6 were similar, suggesting similar ligand binding patterns for these receptors. Thus, cell survival was decreased, glial fibrillary acidic protein (GFAP) expression was reduced, whereas the number of oligodendrocytes increased. No effect on neuronal differentiation was seen. Whereas the expression of Alk2 and Alk3 mRNA remained unchanged, the Alk6 mRNA was induced after impaired BMP signaling. After dnAlk3 overexpression, cell survival and astroglial differentiation increased in parallel to augmented Alk6 receptor signaling. We conclude that endogenous BMPs mediate cell survival, astroglial differentiation and the suppression of oligodendrocytic cell fate mainly via the Alk6 receptor in AHP culture.

We studied the effects of all-trans retinoic acid (ATRA) and Bone morphogenetic protein-6 (BMP-60 on neuronal differentiation of IMR-32 cells.Immunostaining, Western blotting and MTT assays were used to characterize the survival and neuronal phenotype of IMR-32 cells differentiated by ATRA +/- BMP-6.ATRA, BMP-6 and ATRA + BMP-6 treatments each induced dopaminergic neuronal differentiation of the IMR-32 cells as judged by expression of GAP-43, tyrosine hydroxylase and microtubule-associated protein 2ab. ATRA alone induced strong biochemical differentiation, whereas ATRA + BMP-6 treatment synergistically enhanced neurite outgrowth and morphological maturation. When compared with undifferentiated controls, ATRA induced Bcl-2 expression, while loss of Bax expression was observed only in cells differentiated by ATRA + BMP-6. The high Bcl-2/Bax ratio in cells differentiated by ATRA and ATRA + BMP-6, respectively, correlated with the survival of these cells in serum-free media. Upon re-exposure to fresh serum lacking factors, only cells differentiated by ATRA + BMP-6 were unable to resume cell division. In concordance with their morphological maturation, these cells were terminally differentiated when compared with cells differentiated by separate treatment with ATRA or BMP-6.

Hypoxic-ischemic (H-I) injury to neonatal brains can cause a life-long neuronal deficit because of increased susceptibility in the neonatal period. Excitotoxicity due to overstimulation of the N-methyl-d-aspartate receptor (NMDAR) is assumed to be the basis of the injury. However, the ontogenic profile of the susceptibility does not directly correlate with the levels of NMDAR expression. Platelet-derived growth factor B-chain (PDGF-B) has been reported to protect neurons by suppressing the NMDA-evoked current and translocating the glutamate transporter to the cell membrane. Thus, we assessed the relationship between the susceptibility to H-I injury and the expression of PDGF-B in neonatal rat brain. PDGF-B infusion before and after an intrastriatal NMDA injection significantly reduced the size of the lesions in 7-day-old rats, when they are most susceptible and the neuronal expression of PDGF-B is low. Fourteen-day-old neonatal rats were found to be resistant to NMDA injury, even though NMDARs are expressed at high levels in the brain at this age. Inhibition of PDGF-B protein synthesis by antisense oligodeoxynucleotides increased the size of the NMDA-induced lesions up to 6-fold at postnatal day 14, when PDGF-B is expressed at high levels in neurons. These data suggest that PDGF-B is an important physiological modulator of NMDAR excitability in the developing brain, and that the balance between the expression of NMDAR and PDGF-B partly determines the ontogenic susceptibility to brain injury. Enhancement of the PDGF-B/receptor signal pathway might rescue neonatal brains at risk of H-I injury.

Bone morphogenetic proteins (BMPs) and growth differentiation factors (GDFs) are potential therapeutic molecules for the treatment of Parkinson's disease (PO). Here we compare the effects of BMP3, 5, 6, and 7 and GDF5 and 6 in a rat mesencephalic cell culture system that reflects the developmental stage of neurons around birth. High concentrations of BMP5, 6, and 7 and GDF5 and 6 induced astroglial cell fate and a depletion of oligodendrocytes. Only BMP5, 6, and 7, however, significantly increased the number of tyrosine hydroxylase (TH)-positive neurons and induced nuclear translocation of the phosphorylated BMP-restricted Smad in a substantial number of TH- and microtubule-associated protein 2(MAP2ab)-positive cells. None of the proteins protected TH-positive cells against 6-hydroxydopamine-induced oxidative stress. BMP3 was without any effect throughout the studies. We conclude that BMP5, 6, and 7 act directly and independently on precursors of the dopaminergic and astroglial lineage and induce their differentiation. In contrast, GDF5 and 6 primarily affect nonneuronal cells in mesencephalic cultures of this stage.

During postnatal development, the hair follicle (HF) shows cyclic activity with periods of relative resting, active growth (anagen), and regression. We demonstrate that similar to the HF induction in embryonic skin, initiation of a new hair growth phase in postnatal skin requires neutralization of the inhibitory activity of bone morphogenetic protein 4 (BMP4) by the BMP antagonist noggin. In the resting HF, BMP4 mRNA predominates over noggin in the epithelium and mesenchyme, and the BMP receptor IA is prominently expressed in the follicular germ. Anagen development is accompanied by down-regulation of the BMP4 and increased noggin mRNA in the HF. Furthermore, administration of noggin protein induces new hair growth phase in postnatal telogen skin in vivo. In contrast, BMP4 induces selective arrest of anagen development in the non-tylotrich (secondary) HF. As a hair growth inducer, noggin increases Shh mRNA in the HF whereas BMP4 down-regulates Shh. This suggests that modulation of BMP4 signaling by noggin is essential for hair growth phase induction in postnatal skin and that the hair growth-inducing effect of noggin is mediated, at least in part, by Shh.

Platelet-derived growth factor BB (PDGF BB) is a potent mitogen for fibroblasts as well as many other cell types. Interaction of PDGF BB with the PDGF beta receptor (PDGF-betaR) activates numerous signaling pathways and leads to a decrease in receptor expression on the cell surface. PDGF-betaR downregulation is effected at two levels, the immediate internalization of ligand-receptor complexes and the reduction in pdgf-betar mRNA expression. Our studies show that pdgf-betar mRNA suppression is regulated by the c-myc proto-oncogene. Both constitutive and inducible ectopic Myc protein can suppress pdgf-betar mRNA and protein. Suppression of pdgf-betar mRNA in response to Myc is specific, since expression of the related receptor pdgf-alphar is not affected. We further show that Myc suppresses pdgf-betar mRNA expression by a mechanism which is distinguishable from Myc autosuppression. Analysis of c-Myc-null fibroblasts demonstrates that Myc is required for the repression of pdgf-betar mRNA expression in quiescent fibroblasts following mitogen stimulation. In addition, it is evident that the Myc-mediated repression of pdgf-betar mRNA levels plays an important role in the regulation of basal pdgf-betar expression in proliferating cells. Thus, our studies suggest an essential role for Myc in a negative-feedback loop regulating the expression of the PDGF-betaR.

Escape from transforming growth factor-beta (TGF-beta)-induced inhibition of proliferation has been observed in many tumor cells and may contribute to loss of growth control. Smad proteins have been identified as major components in the intracellular signaling of TGF-beta family members. In this study, we examined the expression of receptor-activated, common-mediator and inhibitory Smads by immunohistochemistry in human colorectal cancers. We found increased expression of receptor-activated Smads in a fraction of the tumor cells, while no immunostaining for Smad2, Smad3 or Smad5 and only occasional staining for Smad1/8 was found in epithelial mucosa of normal colon. No or only weak staining for receptor-activated Smads, common-mediator Smad4 and inhibitory Smads was observed in the tumor stroma. Common-mediator Smad4 and inhibitory Smads were detected in cells of both tumor and normal tissues. We observed a distinct pattern of Smad4 immunostaining of epithelial cells along colon crypts, with high expression in zones of terminal differentiation. Our data show selective up-regulation of receptor-activated Smad proteins in human colorectal cancers and suggest involvement of Smad4 in differentiation and apoptosis of surface epithelial cells of normal crypts.

The transforming growth factor-b superfamily is thought to be involved in the regulation and control of growth and diierentiation. These growth factors signal through transmembrane serine/threonine kinase receptors. The activation of type I receptor kinase phosphorylates a family of intracellular signalling proteins called Smads. In the present study, we wanted to localize type I and type II receptors and Smad proteins in human eccrine sweat glands. Expression of transforming growth factor-b type I receptor was restricted to myoepithelial cells only, whereas bone morphogenetic protein receptor IA was found selectively within the duct epithelium of both the dermal portion and the acrosyringium. Bone morphogenetic protein receptor IB antibody gave a faint staining of secretory epithelium and myoepithelial cells. Smad proteins were identi¢ed in diierent parts of the eccrine sweat gland apparatus. In particular, Smad 1 and Smad 3 were localized within myoepithelial cells, whereas coils were stained weakly for Smad 1 and Smad 3. Smad 3 protein was also expressed by the duct epithelium. Smad 2, Smad 4, Smad 5, Smad 6 and Smad 7 were not identi¢ed in eccrine sweat gland epithelia. Our data provide evidence for transforming growth factor-b/ bone morphogenetic protein signalling in the eccrine sweat gland and the selective expression of Smad proteins. Myoepithelial cells and duct cells have been identi¢ed as major targets of the transforming growth factor-b pathway. Possible functions are growth inhibition and control of myoepithelial diierentiation. Key words: sweat glands; transforming growth factor b; Smad proteins; bone morphogenetic proteins.

Transforming growth factor beta (TGF-beta) is involved in the modulation of cell growth, differentiation and repair following injury of various organs. Previous studies on human autopsy material have indicated that TGF-beta isoforms-beta1, -beta2 and -beta3, and TGF-beta receptor type I are expressed in various cells of necrotizing brain lesions like infarction and abscess. The present immunohistochemical study was designed to investigate changes that may occur with regard to TGF-beta and its receptors type I and II in a rat model of focal brain ischemia induced by transient or permanent occlusion of the middle cerebral artery. Our findings indicate that at days 1 and 3 following such transient and permanent ischemia there is an up-regulation of TGF-beta isoforms -beta1, -beta2 and -beta3, and TGF-beta receptor types I and II mainly in the perifocal neurons, reactive astroglial cells, endothelial cells and macrophages.

Fibronectin seems to play an important role in promoting the characteristic changes of vascular smooth muscle cells in diabetes mellitus including overexpression of the platelet-derived growth factor beta-receptor. To determine the regulatory mechanism of the beta-receptor by fibronectin, we have analyzed the effect of fibronectin on the expression of the beta-receptor in cultured rat aortic smooth muscle cells using the beta-receptor promoter/luciferase expression vector system. Fibronectin was found to stimulate the expression of the beta-receptor at the transcriptional level. Both a MEK1 inhibitor PD98059 and a tyrosine kinase inhibitor herbimycin A significantly inhibited the fibronectin-stimulated receptor transcription. Herbimycin A also completely inhibited the fibronectin-stimulated increase in tyrosine phosphorylation of focal adhesion kinase. These data suggest the involvement of the integrin-mediated mitogen-activated protein kinase pathway downstream of fibronectin stimulation in the activation process of the beta-receptor promoter.

Based on successful induction of donor-specific unresponsiveness by alloantigenic stimulation in several animal models of acute rejection, we hypothesized that similar immune manipulations would also inhibit the evolution of chronic rejection and transplant vasculopathy. To induce immune tolerance, DA rats received a PVG heart allograft and were immunosuppressed with cyclosporine for 30 d. At day 100 the animals were challenged with a PVG aortic allograft after either 1 or 18 h of cold ischemia. 8 wk after the aortic transplantation, the grafts were investigated for morphological changes, infiltrating cells, apoptosis, and Fas-Fas ligand expression. Control allografts showed advanced transplant arteriosclerosis, whereas tolerance-induced aortic allografts displayed reduced neointimal formation, less medial atrophy, fewer apoptotic cells, and fewer Fas- and FasL-expressing cells. Prolonged ischemic storage time did not profoundly alter the morphological changes of the allografts. Fas expression was found in T cells, macrophages, vascular smooth muscle cells, and endothelial cells, whereas FasL was expressed mainly by T cells and macrophages. FasL mRNA expression was evident throughout the entire allograft wall. In conclusion, induction of allospecific tolerance can effectively prevent transplant arteriosclerosis. Cold ischemia damage does not abrogate the beneficial effect of tolerance, but creates a separate identity of mainly endothelial lesions. Furthermore, Fas-mediated apoptosis appears to be involved in the pathological lesions seen in chronic rejection.

The expression of platelet-derived growth factor (PDGF) was studied in a rat model of Huntington’s disease, produced by unilateral intrastriatal ibotenic acid injections. The most pronounced effect registered was that the number of PDGF-immunoreactive cells increased in the lesioned area up to 10 weeks after the surgery. Double immunofluorescence staining indicated that the PDGF-positive cells were astrocytes. The increased PDGF immunoreactivity was associated with only minor changes in total PDGF mRNA and PDGF protein levels in the lesioned area. Reverse transcription–polymerase chain reaction (RT-PCR) demonstrated a slight increase in PDGF mRNA after ibotenic acid lesion, but this was not reflected in an increase in PDGF A- and B-chain protein concentration as measured with ELISA. After sham operation an increase in PDGF protein concentration was seen, while the number of PDGF-immunoreactive cells was unchanged. The accumulation of PDGF in the astrocytes might reflect the role of PDGF in a repair process in neurodegenerative processes.

Ischemia induced upregulation of growth factor expression in experimental transplant arteriosclerosis

To determine the regulatory mechanism of the expression of the mouse platelet-derived growth factor (PDGF) beta-receptor gene, a 1.9-kb 5' flanking genomic fragment was cloned and analyzed. Site-directed mutagenesis of a CCAAT motif, located 60 bp upstream of the transcriptional-start site, completely abolished the promoter activity [Ballagi, A. E., Ishisaki, A., Nelin, J.-O.Funa, K. (1995) Biochem. Biophys. Res. Commun. 210, 165-1751. The sequence around the intact CCAAT motif was protected by in vitro DNase-I-footprinting analysis. Electrophoresis-mobility-shift assays with anti-[nuclear factor Y(NF-Y)]Ig revealed binding of the NF-Y complex to the CCAAT box. Furthermore, the double-stranded oligonucleotides corresponding to the sequence around the CCAAT motif were conjugated with DNA-affinity magnetic beads. The binding proteins were affinity purified and identified as the NF-Y transcription factor by western blotting. Our results indicate that NF-Y controls the basal transcription activity of the mouse PDGF beta-receptor gene.

Rats transplanted with the androgen-sensitive, syngeneic Dunning R3327 PAP prostatic tumor were castrated and treated with estrogen or vehicle for 4, 12 and 24 hr and for 6 weeks. Tumor growth was retarded by castration and further inhibited by estrogen. Immediately after castration, an increased number of activated macrophages and T-cells were found in parallel with increasing apoptotic tumor cells. Administration of an immunosuppressive drug, FK 506, abolished the growth-inhibitory effects of castration and estrogen. The tumor growth rate correlated negatively with the number of R73- and OX8-positive T-cells and NK cells and with the percentage of ED3-positive macrophages. There was a positive correlation between the percentage of TdT-mediated-dUTP nick end labeling (TUNEL)-positive apoptotic cells and that of ED3-positive cells. Our results suggest that apoptosis of prostatic carcinoma cells induced by endocrine treatment in vivo is partly due to a rapid infiltration by immunocompetent cells.