Biomedical subjects

Jonny St-Amand

Publications and source records attributed to Jonny St-Amand.

7 recordsLinked to original sources

PubMed2005

Regulation of hypothalamic gene expression by glucocorticoid: implications for energy homeostasis.

The present study investigated the hypothalamic gene expressions regulated by glucocorticoids (GC), key hormones in energy homeostasis. Using the serial analysis of gene expression (SAGE) method, we studied the effects of adrenalectomy (ADX) and GC on the transcriptomes of mouse hypothalamus. Approximately 180,000 SAGE tags, which correspond to 50,000 tag species, were isolated from each group of intact or adrenalectomized mice as well as 1, 3, and 24 h after GC injection. ADX upregulated diazepam binding inhibitor gene expression while downregulating vomeronasal 1 receptor D4, genes involved in mitochondrial phosphorylation (cytochrome-c oxidase 1 and NADH dehydrogenase 3), 3beta-hydroxysteroid dehydrogenase-1, and prostaglandin D2 synthase. GC increased the gene expression levels of dehydrogenase/reductase member 3, prostaglandin D2 synthase, solute carrier family 4 member 4, and five cytoskeletal proteins including myosin light chain phosphorylatable fast and troponin C2 fast. On the other hand, GC reduced the mRNA levels of calmodulin 1 and expressed sequence tag similar to calmodulin 2, ATP synthase F0 subunit 6, and solute carrier family 4 member 3. Moreover, 7 uncharacterized and 43 novel transcripts were modulated by ADX and GC. The present study has identified genes that may regulate hypothalamic systems governing energy balance in response to ADX and GC.

Adrenalectomy↗

PubMed2005

The top 10 most abundant transcripts are sufficient to characterize the organs functional specificity: evidences from the cortex, hypothalamus and pituitary gland.

Using serial analysis of gene expression, we have identified the most abundant mRNA transcripts in parietal cortex, hypothalamus and pituitary gland in adult male mice. High mRNA abundance of neurogranin (cell signalling and communication) was characteristic of the cortex. The common molecular features of cortex and hypothalamus were high abundance of mRNA encoding mitochondrial enzymes such as reduced form of nicotinamide adenine dehydrogenase (NADH) 4 and cytochrome c oxidase 2 (energy metabolism), brain creatine kinase (energy metabolism) and myelin basic protein (cell structure). In the hypothalamus, mRNA levels of apolipoprotein E (lipid metabolism), prostaglandin D2 (cell signalling and communication) and secreted acidic cysteine-rich glycoprotein (extracellular matrix) were especially high. A common molecular feature of the hypothalamus and pituitary was high mRNA abundance of guanine nucleotide binding protein alpha stimulating complex locus (cell signalling and cell communication). The pituitary gland was characterized by high expression of genes encoding hormones such as growth hormone, pro-opiomelanocortin and prolactin, as well as neuronatin (cell differentiation) and four potential novel transcripts. Thus, these results show that the cortex, hypothalamus and pituitary gland can be specifically characterized according to their 10 most abundant transcripts. In addition, the current study serves as a basis for future studies on the potential novel transcripts and the transcripts with unclear functions despite their extremely high abundance, as well as studies on physiology and pathology of the two brain regions and pituitary gland.

Animals↗

PubMed2005

Sexually dimorphic gene expression in the hypothalamus, pituitary gland, and cortex.

We examined sex differences in the transcriptomes of hypothalamus, pituitary gland, and cortex of male and female mice using serial analysis of gene expression. In total 940,669 tags were sequenced. In hypothalamus, 3 transcripts are differentially expressed by gender, including growth hormone (neuromodulation) and 3beta-hydroxysteroid dehydrogenase-1 (steroidogenesis). In pituitary gland, 43 transcripts are differentially expressed, including RAS guanyl-releasing protein 2 (cell signaling), ornithine transporter (mitochondrial transport), H3 histone family 3B (chromatin structure), heterogeneous nuclear ribonucleoprotein U (chromatin remodeling), NADH dehydrogenase (mitochondrial oxidative phosphorylation), neuronatin (cell differentiation), and ribosomal protein S27a (protein metabolism). EST X (inactive)-specific transcript antisense is expressed at a higher level in the three female organs, whereas growth hormone and NADH dehydrogenase are expressed at higher levels in female cortex. Thus, the current study has characterized key sexual dimorphisms in the transcriptomes of the hypothalamus, pituitary, and cortex.

Animals↗

PubMed2005

Regulation of global gene expression by ovariectomy and estrogen in female adipose tissue.

OBJECTIVE: To study the effects of ovariectomy (OVX) and estrogen replacement on global gene expression in white adipose tissue. RESEARCH METHODS AND PROCEDURES: Female mice were randomly divided into four groups: 1) intact, 2) OVX, 3) OVX plus estradiol (E2) injection 3 hours before death (E(2)-3 hours), and 4) E(2)-24 hours. The serial analysis of gene expression was performed to detect the transcriptomic changes. RESULTS: A total of 15 transcripts, including several novel transcripts, were found to be modulated by OVX or E2 (p<0.05). Secreted acidic cysteine-rich glycoprotein, which regulates the extracellular matrix (ECM) components, was increased after OVX. Moreover, OVX up-regulated several transcripts involved in ECM, such as procollagen types Ialpha1 and 2. In cell defense, glutathione peroxidase 3 was lower in OVX than in intact mice. Cytochrome c oxidase I and three novel transcripts were up-regulated by estrogen treatment. DISCUSSION: This study underlines the importance of cell shape and ECM regulation by OVX on adiposity. Moreover, some novel transcripts may also play a relevant role in OVX-induced obesity and estrogen therapy.

Adipose Tissue↗

PubMed2004

Adipose tissue transcriptome by serial analysis of gene expression.

OBJECTIVE: To describe the genomic expression profile or transcriptome of adipose tissue using the serial analysis of gene expression method. RESEARCH METHODS AND PROCEDURES: The serial analysis of gene expression strategy is based on isolation of short sequences (tags), which usually correspond to unique transcripts, and on their concatenation into long DNA molecules, which are then cloned and sequenced. Experiments were performed with mRNA from retroperitoneal adipose tissue of male C57BL6 mice. RESULTS: We isolated 45,996 tags corresponding to more than 17,000 different genes. Eighty-eight genes were expressed at more than 0.1% of the total population and represented 26% of the mRNA population identified. The most expressed genes were: carbonic anhydrase 3 (1.97%), cytochrome c oxidase (COX) 1 (1.47%), COX2 (1.25%), diazepam binding inhibitor (1.04%), a novel transcript (0.87%), COX3 (0.55%), fatty acid-binding protein 4 (0.55%), and NADH dehydrogenase 4 (0.52%). Other genes known to be expressed in adipose tissue, such as uncoupling protein 2, angiotensinogen, adipsin, and insulin-like growth factor 1, were found at a lower level. Several tags corresponding to novel transcripts were also found. DISCUSSION: To our knowledge, the present results provide for the first time a quantitative description of the transcriptome in adipose tissue.

Adipose Tissue↗

PubMed2004

Maximum tolerable dose of red pepper decreases fat intake independently of spicy sensation in the mouth.

Dietary red pepper suppresses energy intake and modifies macronutrient intake. We have investigated whether a stimulus in the mouth and the sensation of spiciness are necessary for red pepper-induced changes in energy and macronutrient intake in human volunteers. In a preliminary test, sixteen Japanese male volunteers tasted samples of a soup with graded doses of red pepper in order to define a moderate and a maximum tolerable (strong) dose of red pepper. On the day of the experiment, a standardised breakfast was given to the volunteers. At lunchtime, the subjects ingested one of four experimental soups containing either a placebo, a moderate or a strong dose of red pepper plus placebo capsules, or a placebo soup plus capsules delivering a strong dose of red pepper. The rest of the meal was given ad libitum to all subjects. The amount of food, protein and carbohydrate ingested was similar for all conditions. Energy and fat intake were similar after the ingestion of the moderate soup compared with placebo. However, the strong soup significantly lowered fat intake compared with placebo (P=0.043), and ingestion of strong capsules also tended to suppress it (P=0.080). Moreover, energy intake after strong soup and capsules tended to be lower than placebo (P=0.089 and 0.076, respectively). The present results indicate that the maximum tolerable dose is necessary to have a suppressive effect of red pepper on fat intake. The main site of the action of red pepper is not in the mouth.

Adult↗

PubMed2003

Serial analysis of gene expression in the skeletal muscle of endurance athletes compared to sedentary men.

Physical exercise produces several adaptive changes in skeletal muscle. However, the molecular mechanisms of these effects are poorly understood. We performed serial analysis of gene expression (SAGE) to quantify the global gene expression profile in sedentary and endurance-trained muscle. A total of 10869 SAGE tags was sequenced and represented 4727 genes. The genes most expressed in muscle are mainly involved in contraction and energy metabolism. Thirty-three genes were differentially expressed between endurance athletes and sedentary individuals. Four genes such as myosin binding protein C fast-type, glycogen phosphorylase, and pyruvate kinase were expressed less in endurance athletes, whereas eight genes coding for expressed sequence tag similar to (EST) crystallin alpha B, EST myosin light chain 2, EST surfactant pulmonary-associated protein A1, EST thrombospondin, EST fructose-bisphosphate aldolase A, EST cytochrome oxidase 1, NADH dehydrogenase 3, and G8 protein were up-regulated. Most of the up-regulated tags corresponded to novel genes. On the other hand, different isoforms of fructose-bisphosphate aldolase A were also differentially expressed. The current study underlying the most highly expressed genes allows a better understanding of global muscle characteristics in normal and endurance-trained individuals. Moreover, the current data suggest novel candidate genes that may be responsible for enhanced endurance performance.

Adult↗