Transformation fingerprint: induced STAT3-C, v-Src and Ha-Ras cause small initial changes but similar established profiles in mRNA

Induced transformation of mouse fibroblasts was carried out by releasing tetracycline-repressed expression of an oncogenic mutant of STAT3, STAT3-C, or of v-Src or Ha-Ras. At 15 days after derepression of each oncogene, DNA microarrays showed elevation (>3-fold) of a similar group of approximately 25 mRNAs compared to untransformed cells. RT-PCR confirmed a number of these mRNA elevations. RNA samples were then analysed at intervals during the first 24 h after doxycycline removal to determine the time of early changes. Extensive changes were not observed by array analysis, except in v-Src-expressing cells where about 10 mRNAs were elevated threefold or more. However, RT-PCR did uncover changes in each derepressed cell type that included some of the changes observed after the 15-day transformation period. In addition, STAT3-C target genes such as BclXI and cyclin D1, which were not observed on array analysis, were elevated by RT-PCR analysis. We conclude, therefore, that early after oncogene induction, transcriptional changes, including those initiated by STAT3-C, may occur only in scarce mRNA and/or to a limited extent. However, with additional time and probably additional cell division, a new epigenetic state is established that is mirrored by a changed transcriptional profile emblematic of transformation by each of three oncogenes.

Gene expression in gastrointestinal stromal tumors is distinguished by KIT genotype and anatomic site

PURPOSE

Gastrointestinal stromal tumors (GISTs) are specific KIT expressing and KIT-signaling driven mesenchymal tumors of the human digestive tract, many of which have KIT-activating mutations. Previous studies have found a relatively homogeneous gene expression profile in GIST, as compared with other histological types of sarcomas. Transcriptional heterogeneity within clinically or molecularly defined subsets of GISTs has not been previously reported. We tested the hypothesis that the gene expression profile in GISTs might be related to KIT genotype and possibly to other clinicopathological factors.

EXPERIMENTAL DESIGN

An HG-U133A Affymetrix chip (22,000 genes) platform was used to determine the variability of gene expression in 28 KIT-expressing GIST samples from 24 patients. A control group of six intra-abdominal leiomyosarcomas was also included for comparison. Statistical analyses (t tests) were performed to identify discriminatory gene lists among various GIST subgroups. The levels of expression of various GIST subsets were also linked to a modified version of the growth factor/KIT signaling pathway to analyze differences at various steps in signal transduction.

RESULTS

Genes involved in KIT signaling were differentially expressed among wild-type and mutant GISTs. High gene expression of potential drug targets, such as VEGF, MCSF, and BCL2 in the wild-type group, and Mesothelin in exon 9 GISTs were found. There was a striking difference in gene expression between stomach and small bowel GISTs. This finding was validated in four separate tumors, two gastric and two intestinal, from a patient with familial GIST with a germ-line KIT W557R substitution.

CONCLUSIONS

GISTs have heterogeneous gene expression depending on KIT genotype and tumor location, which is seen at both the genomic level and the KIT signaling pathway in particular. These findings may explain their variable clinical behavior and response to therapy.

A comparison of cDNA, oligonucleotide, and Affymetrix GeneChip gene expression microarray platforms

We have conducted a study to compare the variability in measured gene expression levels associated with three types of microarray platforms. Total RNA samples were obtained from liver tissue of four male mice, two each from inbred strains A/J and C57BL/6J. The same four samples were assayed on Affymetrix Mouse Genome Expression Set 430 GeneChips (MOE430A and MOE430B), spotted cDNA microarrays, and spotted oligonucleotide microarrays using eight arrays of each type. Variances associated with measurement error were observed to be comparable across all microarray platforms. The MOE430A GeneChips and cDNA arrays had higher precision across technical replicates than the MOE430B GeneChips and oligonucleotide arrays. The Affymetrix platform showed the greatest range in the magnitude of expression levels followed by the oligonucleotide arrays. We observed good concordance in both estimated expression level and statistical significance of common genes between the Affymetrix MOE430A GeneChip and the oligonucleotide arrays. Despite their apparently high precision, cDNA arrays showed poor concordance with other platforms.

Casein Kinase II Alpha Subunit and C1-Inhibitor Are Independent Predictors of Outcome in Patients with Squamous Cell Carcinoma of the Lung

PURPOSE

Gene expression profiling has been shown to be a valuable tool for prognostication and identification of cancer-associated genes in human malignancies. We aimed to identify potential prognostic marker(s) in non-small cell lung cancers using global gene expression profiles.

EXPERIMENTAL DESIGN

Twenty-one previously untreated patients with non-small cell lung cancer were analyzed using the Affymetrix GeneChip high-density oligonucleotide array and comparative genomic hybridization. Identified candidate genes were validated in an independent cohort of 45 patients using quantitative real-time reverse transcription-PCR and Western blot analyses. Follow-up data for these patients was collected and used to assess outcome correlations.

RESULTS

Hierarchical clustering analysis yielded three distinct subgroups based on gene expression profiling. Cluster I consisted of 4 patients with adenocarcinoma and 1 with squamous cell carcinoma (squamous cell carcinoma); clusters II and III consisted of 6 and 10 patients with squamous cell carcinoma, respectively. Outcome analysis was performed on the cluster groups containing solely squamous cell carcinoma, revealing significant differences in disease-specific survival rates. Moreover, patients having a combination of advanced Tumor-Node-Metastasis stage and assigned to the poor prognosis cluster group (cluster II) had significantly poorer outcomes. Comparative genomic hybridization analysis showed recurrent chromosomal losses at 1p, 3p, 17, 19, and 22 and gains/amplifications at 3q, 5p, and 8q, which did not vary significantly between the cluster groups. We internally and externally validated a subset of 11 cluster II (poor prognosis)-specific genes having corresponding chromosomal aberrations identified by comparative genomic hybridization as prognostic markers in an independent cohort of patients with lung squamous cell carcinoma identifying CSNK2A1 and C1-Inh as independent predictors of outcome.

CONCLUSION

CSNK2A1 and C1-Inh are independent predictors of survival in lung squamous cell carcinoma patients and may be useful as prognostic markers.

Assessment of molecularly imprinted sol–gel materials for selective room temperature phosphorescence recognition of nafcillin

Sol-gel imprinted materials were prepared against nafcillin, a semisynthetic beta-lactamic antibiotic employed in the treatment of serious infections caused by penicillinase-producing staphylococci. Two approaches were addressed for preparation of the imprinted materials and the controls: as conventional monoliths, which were ground and sieved to a desired particle size for rebinding analysis, and as films on supporting glass slides. The specific binding sites that are created during the imprinting process are analyzed via selective room temperature phosphorescence (RTP) (sol-gel films) measurements as well as via competitive room temperature phosphorescence ligand assay. Results demonstrated the importance of the physical configuration of the imprinted material for minimizing non-specific binding. The close similarities between the structures of different beta-lactamic antibiotics made it possible to interpret the roles of the template structure on specific molecular recognition. In this article, we introduce the use of room temperature phosphorescence as selective transduction method for the template. The imprinted sol-gel films displayed enhanced specific binding characteristics respect to the monolithic sol-gel and can be envisaged for the use as recognition matrices for the screening and rapid selection of antibiotics from a combinatorial library or for the rapid control of nafcillin in biological samples (e.g. milk, serum, urine).

Oncogenic Ras and Akt signaling contribute to glioblastoma formation by differential recruitment of existing mRNAs to polysomes

In order to determine the global effects of oncogenic Ras and Akt signaling pathways on translational efficiencies, we compared the gene expression profiles of total cellular mRNA and mRNA associated with polysomes. We found that the immediate effect of Ras and Akt signaling blockade on transcription was relatively modest; however, the profile of mRNA associated with polysomes was substantially altered. These observations indicate that the immediate effect of Ras and Akt signaling regulates the recruitment of specific mRNAs to ribosomes to a far greater extent than they regulate the production of mRNAs by transcriptional effects. The mRNAs most affected are those encoding proteins that regulate growth, transcription regulation, cell to cell interactions, and morphology. These data support a model whereby Ras and Akt signaling primarily lead to cellular transformation by altering the transcriptome and producing a radical shift in the composition of mRNAs associated with actively translating polysomes.

Optimization of a culture medium for ligninolytic enzyme production and synthetic dye decolorization using response surface methodology

A Box-Wilson central composite design was applied to optimize copper, veratryl alcohol and l-asparagine concentrations for Trametes trogii (BAFC 212) ligninolytic enzyme production in submerged fermentation. Decolorization of different dyes (xylidine, malachite green, and anthraquinone blue) by the ligninolytic fluids from the cultures was compared. The addition of copper stimulated laccase and glyoxal oxidase production, but this response was influenced by the medium N-concentration, with improvement higher at low N-levels. The medium that supported the highest ligninolytic production (22.75 U/ml laccase, 0.34 U/ml manganese peroxidase, and 0.20 U/ml glyoxal oxidase) also showed the greatest ability to decolorize the dyes. Only glyoxal oxidase activity limited biodecoloration efficiency, suggesting the involvement of peroxidases in the process. The addition of 1-hydroxybenzotriazole (a known laccase mediator) to the ligninolytic fluids increased both their range and rate of decolorization. The cell-free supernatant did not decolorize xylidine, poly R-478, azure B, and malachite green as efficiently as the whole broth, but results were similar in the case of indigo carmine and remazol brilliant blue R. This indicates that the mycelial biomass may supply other intracellular or mycelial-bound enzymes, or factors necessary for the catalytic cycle of the enzymes. It also implies that this fungus implements different strategies to degrade dyes with diverse chemical structures.

The oncogene Nup98-HOXA9 induces gene transcription in myeloid cells

The nucleoporin Nup98 gene is frequently rearranged in acute myelogenous leukemia (AML). In most cases this results in fusion of the N terminus of Nup98 to the DNA binding domain of a homeodomain transcription factor. The prototype of these fusions, Nup98-HOXA9, is associated with human AML and induces AML in mouse models. To understand the mechanisms by which Nup98-HOXA9 causes AML, we expressed it in myeloid cells and identified its target genes using high density oligonucleotide microarrays. The analysis was performed in triplicate and was confirmed by quantitative real time PCR. Of the 102 Nup98-HOXA9 target genes identified, 92 were up-regulated, and only 10 were down-regulated, suggesting a transcriptional activation function. A similar analysis of wild-type HOXA9 revealed 13 target genes, 12 of which were up-regulated, and 1 was down-regulated. In contrast, wild-type Nup98 had no effect on gene expression, demonstrating that the HOXA9 DNA binding domain is required for gene regulation. Co-transfection experiments using a luciferase reporter linked to the promoter of one of the Nup98-HOXA9 target genes confirmed up-regulation at the transcriptional level by Nup98-HOXA9 but not by either HOXA9 or Nup98. These data indicate that Nup98-HOXA9 is an aberrant transcription factor whose activity depends on the HOXA9 DNA binding domain but has a stronger and wider transcriptional effect than HOXA9. Several of the genes regulated by Nup98-HOXA9 are associated with increased cell proliferation and survival as well as drug metabolism, providing insights into the pathogenesis and epidemiology of Nup98-HOXA9-induced AML.

Classification of clear-cell sarcoma as a subtype of melanoma by genomic profiling

PURPOSE

To develop a genome-based classification scheme for clear-cell sarcoma (CCS), also known as melanoma of soft parts (MSP), which would have implications for diagnosis and treatment. This tumor displays characteristic features of soft tissue sarcoma (STS), including deep soft tissue primary location and a characteristic translocation, t(12;22)(q13;q12), involving EWS and ATF1 genes. CCS/MSP also has typical melanoma features, including immunoreactivity for S100 and HMB45, pigmentation, MITF-M expression, and a propensity for regional lymph node metastases.

MATERIALS AND METHODS

RNA samples from 21 cell lines and 60 pathologically confirmed cases of STS, melanoma, and CCS/MSP were examined using the U95A GeneChip (Affymetrix, Santa Clara, CA). Hierarchical cluster analysis, principal component analysis, and support vector machine (SVM) analysis exploited genomic correlations within the data to classify CCS/MSP.

RESULTS

Unsupervised analyses demonstrated a clear distinction between STS and melanoma and, furthermore, showed that CCS/MSP cluster with the melanomas as a distinct group. A supervised SVM learning approach further validated this finding and provided a user-independent approach to diagnosis. Genes of interest that discriminate CCS/MSP included those encoding melanocyte differentiation antigens, MITF, SOX10, ERBB3, and FGFR1.

CONCLUSION

Gene expression profiles support the classification of CCS/MSP as a distinct genomic subtype of melanoma. Analysis of these gene profiles using the SVM may be an important diagnostic tool. Genomic analysis identified potential targets for the development of therapeutic strategies in the treatment of this disease.

Induction of C/EBPalpha activity alters gene expression and differentiation of human CD34+ cells

The CCAAT/enhancer binding protein alpha (C/EBPalpha) belongs to a family of transcription factors that are involved in the differentiation process of numerous tissues, including the liver and hematopoietic cells. C/EBPalpha(-/-) mice show a block in hematopoietic differentiation, with an accumulation of myeloblasts and an absence of mature granulocytes, whereas expression of C/EBPalpha in leukemia cell lines leads to granulocytic differentiation. Recently, dominant-negative mutations in the C/EBPalpha gene and down-regulation of C/EBPalpha by AML1-ETO, an AML associated fusion protein, have been identified in acute myelogenous leukemia (AML). To better understand the role of C/EBPalpha in the lineage commitment and differentiation of hematopoietic progenitors, we transduced primary human CD34(+) cells with a retroviral construct that expresses the C/EBPalpha cDNA fused in-frame with the estrogen receptor ligand-binding domain. Induction of C/EBPalpha function in primary human CD34(+) cells, by the addition of beta-estradiol, leads to granulocytic differentiation and inhibits erythrocyte differentiation. Using Affymetrix (Santa Clara, CA) oligonucleotide arrays we have identified C/EBPalpha target genes in primary human hematopoietic cells, including granulocyte-specific genes that are involved in hematopoietic differentiation and inhibitor of differentiation 1 (Id1), a transcriptional repressor known to interfere with erythrocyte differentiation. Given the known differences in murine and human promoter regulatory sequences, this inducible system allows the identification of transcription factor target genes in a physiologic, human hematopoietic progenitor cell background.

Segmental duplications in euchromatic regions of human chromosome 5: a source of evolutionary instability and transcriptional innovation

Recent analyses of the structure of pericentromeric and subtelomeric regions have revealed that these particular regions of human chromosomes are often composed of blocks of duplicated genomic segments that have been associated with rapid evolutionary turnover among the genomes of closely related primates. In the present study, we show that euchromatic regions of human chromosome 5-5p14, 5p13, 5q13, 5q15-5q21-also display such an accumulation of segmental duplications. The structure, organization and evolution of those primate-specific sequences were studied in detail by combining in silico and comparative FISH analyses on human, chimpanzee, gorilla, orangutang, macaca, and capuchin chromosomes. Our results lend support to a two-step model of transposition duplication in the euchromatic regions, with a founder insertional event at the time of divergence between Platyrrhini and Catarrhini (25-35 million years ago) and an apparent burst of inter- and intrachromosomal duplications in the Hominidae lineage. Furthermore, phylogenetic analysis suggests that the chronology and, likely, molecular mechanisms, differ regarding the region of primary insertion-euchromatic versus pericentromeric regions. Lastly, we show that as their counterparts located near the heterochromatic region, the euchromatic segmental duplications have consistently reshaped their region of insertion during primate evolution, creating putative mosaic genes, and they are obvious candidates for causing ectopic rearrangements that have contributed to evolutionary/genomic instability.

Degradation of environmental pollutants by Trametes trogii

The ability of the ligninolytic fungus Trametes trogii to degrade in vitro different xenobiotics (PCBs, PAHs and dyes) was evaluated. Either 200 ppm of a PCB mixture (Aroclor 1150) or 160 ppm of an industrial PAH mixture (10% V/V of PAHs, principal components hexaethylbenzene, naphthalene, 1-methyl naphthalene, acenaphthylene, anthracene, fluorene and phenanthrene), were added to trophophasic and idiophasic cultures growing in a nitrogen limited mineral medium (glucose/asparagine) and in a complex medium (malt extract/glucose). Gas-liquid chromatography proved that within 7 to 12 d more than 90% of the organopollutants added were removed. The decrease in absorbance at 620 nm demonstrated that cultures of this fungus were able to transform 80% of the dye Anthraquinone-blue (added at a concentration of 50 ppm) in 1.5 h. Enzyme estimations indicated high activity of laccase (up to 0.55 U/mL), as well as lower production of manganese-peroxidase. Laccase activity, detected in all the conditions assayed, could be implicated in the degradation of these organopollutants. Considering the results obtained, T. trogii seems promising for detoxification.

[Degradation of anthraquinone blue by Trametes trogii]

The ability of the white rot fungus Trametes trogii BAFC 463 (high producer of ligninolytic enzymes, especially laccase and manganese peroxidase) to degrade the dye anthraquinone blue, refractory to bacterial attack, was evaluated. Both tropho- and idiophasic T. trogii cultures in synthetic medium (glucose/asparagine) and complex medium (malt extract/glucose) were able to transform up to 88% dye in 4 hours. The activity of laccase, an oxygen-dependent phenoloxidase which was present at high levels in all the conditions assayed, might be related to the ability of the fungus to degrade the colorant. This is supported by the fact that in bioreactor experiences carried out at pH 4.5 the addition of anthraquinone blue caused a decrease in the levels of soluble oxygen. However, although high levels of laccase were produced at pH 7.5, the enzyme was not active, and neither dye transformation nor loss in the levels of soluble oxygen were quantified.

Phenotypic and genotypic study of Streptococcus agalactiae in vagina of pregnant women in Argentina

Streptococcus agalactiae (GBS) is a leading cause of serious neonatal infection. In this study we determine the prevalence, serotype distribution and genomic diversity of GBS in vagina of pregnant women. Vaginal swabs of 531 pregnant women were cultured on Columbia Agar Base Blood, GBS Agar Base and Todd Hewitt Broth. GBS were characterized by group and type-specific agglutination. Genomic polymorphism was studied by random amplification of DNA (RAPD). Seventeen patients (3.2%) were positive for GBS, resulting serotype III the most frequent. RAPD detected 16 different RAPD profiles from 21 GBS studied, revealing a good discriminatory power. In this sense, this method showed different genotype from GBS serotype III recovered from successive samples of two patients, suggesting reinfection. In conclusion, the combination of RAPD and serotyping appear promising for epidemiological studies. Finally, findings of reinfection after therapy during pregnancy, led us to suggest performing prenatal GBS screening and intrapartum prophylaxis in order to reduce neonatal risk.

Biosynthesis of fatty acids and triacylglycerols by 2,6,10,14-tetramethyl pentadecane-grown cells of Nocardia globerula 432

Nocardia globerula strain 432 was able to synthesize triacylglycerols (TAG) during cultivation on 2,6,10,14-tetramethyl pentadecane (pristane) under nitrogen-limiting conditions. Within these cells, 4,8,12-trimethyl tridecanoic acid was the major fatty acid detected. Fatty acids with an odd number of carbon atoms and minor amounts of even-numbered fatty acids were also observed. Experiments carried out with acrylic acid, an inhibitor of beta-oxidation, suggested that odd-numbered fatty acids such as C15:0, C17:0 and 10-methyl C17:0 were synthesized de novo using propionyl-CoA, the beta-oxidation product, as precursor. Although N. globerula 432 incorporated mainly straight chain fatty acids into TAG, the branched fatty acid 4,8,12-trimethyl tridecanoic acid also appeared, to some extent, in the acylglycerols. The importance of TAG biosynthesis by pristane-grown cells of N. globerula strain 432 is discussed.

Detection of breast cancer cell contamination in leukapheresis product by real-time quantitative polymerase chain reaction

Identification of sensitive techniques for breast cancer cell detection might be relevant for high-dose chemotherapy programs with autologous stem cell transplantation. We investigated the feasibility of Maspin, Mammaglobin and c-ErbB-2 amplification by real-time quantitative polymerase chain reaction (RQ-PCR) for the detection of breast cancer cells in leukaphereses. Expression of the three markers was determined in primary breast cancers and cell lines. Peripheral blood (PB), bone marrow (BM), and leukapheresis samples from patients with malignancies other than breast cancer were used as controls. Sensitivity was evaluated by dilution of primary tumors and cell lines with mononuclear blood cells. We found expression of the three markers in all primary tumors and most cell lines. No blood specimen from control patients had the Maspin transcript, while only one was positive for Mammaglobin. Weak c-ErbB-2 expression was detectable in most PB, all BM and all leukapheresis samples from controls. We observed a low sensitivity of Maspin RQ-PCR and a sensitivity of Mammaglobin RQ-PCR up to one tumor cell in 10(6) mononuclear cells. One out of 18 leukaphereses from breast cancer patients screened for the presence of Mammaglobin mRNA was positive. We conclude that Mammaglobin RQ-PCR might be a useful tool for detection of leukapheresis contamination.

Structure and expression of the variant melanin-concentrating hormone genes: only PMCHL1 is transcribed in the developing human brain and encodes a putative protein

PMCHL1 and PMCHL2 are two copies of the so-called variant melanin-concentrating hormone (MCH) gene that are located, respectively, on human chromosome 5p14 and 5q13 and that emerged recently during primate evolution. They correspond to a 5'-end truncated version of the MCH gene mapped on chromosome 12q23 and encoding a neuropeptide precursor. The gene organization and regulation of the expression of the variant MCH genes in the human brain are the central issues we investigated. First, the structure and fine chromosomal mapping of the 5p and 5q variant MCH genes were established. These revealed several point mutations and length variations of one CA/TA repeat which allow discrimination between each copy. Using a combination of RACE-PCR, RT-PCR, and sequencing analysis, we provided strong evidence for the expression of the PMCHL1 gene but not the PMCHL2 gene in the human fetal, newborn, and adult brains. Sense, potentially coding, RNAs, as well as noncoding antisense RNAs, were identified and displayed a region-specific expression in the human brain. Strikingly, sense unspliced RNAs of the PMCHL1 gene carried a novel open reading frame and may produce an NLS-containing protein of 8 kDa named VMCH-p8. These transcripts were translated in vitro and in transfected COS cells. Therefore, the PMCHL1 gene provides a unique example of the generation of a gene in the Hominoidae lineage which is specifically transcribed in the developing human brain and has the capacity to be translated into a putative novel protein.

Cellular localization and role of prohormone convertases in the processing of pro-melanin concentrating hormone in mammals

Melanin concentrating hormone (MCH) and neuropeptide EI (NEI) are two peptides produced from the same precursor in mammals, by cleavage at the Arg145-Arg146 site and the Lys129-Arg130 site, respectively. We performed co-localization studies to reveal simultaneously the expression of MCH mRNA and proconvertases (PCs) such as PC1/3 or PC2. In the rat hypothalamus, PC2 was present in all MCH neurons, and PC1/3 was present in about 15-20% of these cells. PC1/3 or PC2 was not found in MCH-positive cells in the spleen. In GH4C1 cells co-infected with vaccinia virus (VV):pro-MCH along with VV:furin, PACE4, PC1/3, PC2, PC5/6A, PC5/6B, or PC7, we observed only efficient cleavage at the Arg145-Arg146 site to generate mature MCH. Co-expression of pro-MCH together with PC2 and 7B2 resulted in very weak processing to NEI. Comparison of pro-MCH processing patterns in PC1/3- or PC2-transfected PC12 cells showed that PC2 but not PC1/3 generated NEI. Finally, we analyzed the pattern of pro-MCH processing in PC2 null mice. In the brain of homozygotic mutants, the production of mature NEI was dramatically reduced. In contrast, MCH content was increased in the hypothalamus of PC2 null mice. In the spleen, a single large MCH-containing peptide was identified in both wild type and PC2 null mice. Together, our data suggest that pro-MCH is processed differently in the brain and in peripheral organs of mammals. PC2 is the key enzyme that produces NEI, whereas several PCs may cleave at the Arg145-Arg146 site to generate MCH in neuronal cell types.

Effects of leptin on melanin-concentrating hormone expression in the brain of lean and obese Lep(ob)/Lep(ob) mice

The effect of leptin on the expression of melanin-concentrating hormone (MCH) was investigated in lean and genetically obese Lepob/Lepob mice. Murine leptin was subcutaneously infused using osmotic minipumps. The treatment period extended to 7 days and the daily dose of leptin delivered was 100 microgram/kg of body weight. In situ hybridization was used to assess the effects of leptin infusion on the expression of MCH mRNA. MCH levels in the brain (hypothalamus/thalamus and the remaining part), spleen and testis were measured by radioimmunoassay coupled to HPLC of selected tissue extracts. Leptin significantly reduced final body weight, weight of brown adipose tissue, daily food intake in obese mice but not in lean animals. In obese mice, leptin led to a rapid reduction in food intake which reached statistical significance after only 24 h and which led to a significant reduction in the body weight after 3 days of treatment. Leptin restored the normal circulating levels of glucose and insulin in obese mice. The present results mainly provide evidence for a stimulating effect of leptin infusion on the MCH neuronal system. The hypothalamic/thalamic levels of MCH mRNA and peptide were higher in mice treated with leptin than in mice infused with phosphate-buffered saline. The stimulation of MCH neurons appeared particularly intense in obese mice, in which the effects of leptin infusion led to the reduction in MCH content of neuron fibers and terminals. Leptin did not affect spleen and testis MCH contents. In the light of the acknowledged orexigenic effects of MCH, the results of this study questioned the direct role of MCH in the action of leptin on energy balance. The increase in MCH expression following leptin could occur as a mechanism to compensate the decrease in energy deposition led to by leptin. It may also indicate that MCH mediates the metabolic actions of leptin indirectly or else that leptin influences actions of MCH other than those related to the regulation of energy balance.

17beta-estradiol regulation of melanin-concentrating hormone and neuropeptide-E-I contents in cynomolgus monkeys: a preliminary study

Melanin-concentrating hormone (MCH) and neuropeptide-E-I (NEI) regulate several behaviors and neuroendocrine functions in rats. Possible influence of these peptides on sexual behavior and reproduction in mammals other than rodents prompted us to investigate: 1) The sites of synthesis of MCH and NEI in the brain of a non-human primate (M. fascicularis); 2) The effect of 17 beta-estradiol (E2) benzoate (E2B) on pro-MCH-derived peptide concentrations in the hypothalamus of the ovariectomized (OVX) cynomolgus monkeys (M. fascicularis). Expression of MCH mRNA and peptides was examined by Northern blotting, RT-PCR and RP-HPLC/RIA. Our results demonstrate that the MCH gene is predominantly expressed in hypothalamus of macaque. E2B exposure of OVX monkeys provoked parallel phasic variations in the MCH-immunoreactivity (IR) and NEI-IR. NEI-IR and to a lesser extent MCH-IR, showed a transient increase (associated with the estradiol peak) at 30 h with a final rise of both MCH-IR and NEI-IR observed at the time (72 h post E2B) of the luteinizing hormone (LH) surge. RP-HPLC analysis of peptide extracts revealed the presence, in addition to mature MCH and NEI, of different MCH-IR and NEI-IR forms in the hypothalami of control and E2B-treated monkeys. Taken together, our results indicated that hypothalamic MCH and NEI contents are regulated after E2B treatment and they suggest the possible involvement of these peptides in the regulation of the pre-ovulatory midcycle LH surge in primates.