Cotranscription and intergenic splicing of the PPARG and TSEN2 genes in cattle

BACKGROUND: Intergenic splicing resulting in the combination of mRNAs sequences from distinct genes is a newly identified mechanism likely to contribute to protein diversity. Few cases have been described, most of them involving neighboring genes and thus suggesting a cotranscription event presumably due to transcriptional termination bypass. RESULTS: We identified bovine chimeric transcripts resulting from cotranscription and intergenic splicing of two neighboring genes, PPARG and TSEN2. These two genes encode the Peroxisome Proliferator Activated Receptors γ1 and γ2 and the tRNA Splicing Endonuclease 2 homolog and are situated in the same orientation about 50 kb apart on bovine chromosome 22q24. Their relative position is conserved in human and mouse. We identified two types of chimeric transcripts containing all but the last exon of the PPARG gene followed by all but the first exon of the TSEN2 gene. The two chimers differ by the presence/absence of an intermediate exon resulting from transcription of a LINE L2 sequence situated between the two genes. Both transcripts use canonical splice sites for all exons coming from both genes, as well as for the LINE L2 sequence. One of these transcripts harbors a premature STOP codon and the other encodes a putative chimeric protein combining most of the PPARγ protein and the entire TSEN2 protein, but we could not establish the existence of this protein. CONCLUSION: By showing that both individual and chimeric transcripts are transcribed from PPARG and TSEN2, we demonstrated regulation of transcription termination. Further, the existence and functionality of a chimeric protein harboring active motifs that are a priori unrelated is hypothesized

Maternal Protein Restriction in Rats Alters Postnatal Growth and Brain Lipid Sensing in Female Offspring

Perinatal nutrition is a key player in the susceptibility to developing metabolic diseases in adulthood, leading to the concept of “metabolic programming”. The aim of this study was to assess the impact of maternal protein restriction during gestation and lactation on glucose homeostasis and eating behaviour in female offspring. Pregnant rats were fed a normal or protein-restricted (PR) diet and followed throughout gestation and lactation. Body weight, glucose homeostasis, and eating behaviour were evaluated in offspring, especially in females. Body weight gain was lower in PR dams during lactation only, despite different food and water intakes throughout gestation and lactation. Plasma concentration of leptin, adiponectin and triglycerides increased drastically before delivery in PR dams in relation to fat deposits. Although all pups had identical birth body weight, PR offspring body weight differed from control offspring around postnatal day 10 and remained lower until adulthood. Offspring glucose homeostasis was mildly impacted by maternal PR, although insulin secretion was reduced for PR rats at adulthood. Food intake, satiety response, and cerebral activation were examined after a lipid preload and demonstrated some differences between the two groups of rats. Maternal PR during gestation and lactation does induce extrauterine growth restriction, accompanied by alterations in maternal plasma leptin and adiponectin levels, which may be involved in programming the alterations in eating behaviour observed in females at adulthood

Maternal Protein Restriction in Rats Alters Postnatal Growth and Brain Lipid Sensing in Female Offspring

Perinatal nutrition is a key player in the susceptibility to developing metabolic diseases in adulthood, leading to the concept of “metabolic programming”. The aim of this study was to assess the impact of maternal protein restriction during gestation and lactation on glucose homeostasis and eating behaviour in female offspring. Pregnant rats were fed a normal or protein-restricted (PR) diet and followed throughout gestation and lactation. Body weight, glucose homeostasis, and eating behaviour were evaluated in offspring, especially in females. Body weight gain was lower in PR dams during lactation only, despite different food and water intakes throughout gestation and lactation. Plasma concentration of leptin, adiponectin and triglycerides increased drastically before delivery in PR dams in relation to fat deposits. Although all pups had identical birth body weight, PR offspring body weight differed from control offspring around postnatal day 10 and remained lower until adulthood. Offspring glucose homeostasis was mildly impacted by maternal PR, although insulin secretion was reduced for PR rats at adulthood. Food intake, satiety response, and cerebral activation were examined after a lipid preload and demonstrated some differences between the two groups of rats. Maternal PR during gestation and lactation does induce extrauterine growth restriction, accompanied by alterations in maternal plasma leptin and adiponectin levels, which may be involved in programming the alterations in eating behaviour observed in females at adulthood

A high-density linkage map of the RN region in pigs

The porcine RN locus affects muscle glycogen content and meat quality. We previously mapped the RN locus to chromosome 15. This study describes the identification of polymorphisms for four class I and four class II markers located in the RN region. Resource families were genotyped with F-SSCP markers (fluorescent single strand conformation polymorphism) and microsatellite markers. Subsequent multipoint linkage analysis revealed the order FN1-IGFBP5-S1000-S1001-IL8RB-VIL1-RN-Sw936-Sw906. The gene order is identical to the previously reported porcine RH map of the same region. The described map will facilitate positional cloning of the RN gene

Protein Content and Methyl Donors in Maternal Diet Interact to Influence the Proliferation Rate and Cell Fate of Neural Stem Cells in Rat Hippocampus

Maternal diet during pregnancy and early postnatal life influences the setting up of normal physiological functions in the offspring. Epigenetic mechanisms regulate cell differentiation during embryonic development and may mediate gene/environment interactions. We showed here that high methyl donors associated with normal protein content in maternal diet increased the in vitro proliferation rate of neural stem/progenitor cells isolated from rat E19 fetuses. Gene expression on whole hippocampi at weaning confirmed this effect as evidenced by the higher expression of the Nestin and Igf2 genes, suggesting a higher amount of undifferentiated precursor cells. Additionally, protein restriction reduced the expression of the insulin receptor gene, which is essential to the action of IGFII. Inhibition of DNA methylation in neural stem/progenitor cells in vitro increased the expression of the astrocyte-specific Gfap gene and decreased the expression of the neuron-specific Dcx gene, suggesting an impact on cell differentiation. Our data suggest a complex interaction between methyl donors and protein content in maternal diet that influence the expression of major growth factors and their receptors and therefore impact the proliferation and differentiation capacities of neural stem cells, either through external hormone signals or internal genomic regulation

L’Epigénétique

L’Epigénétique. Ecole Chercheurs - Nutrition périnatale "Enjeux et conséquences pour l'alimentation humaine et les pratiques d'élevage

Early life nutrition and long term appetite regulation

International audienceFeeding behavior is a complex trait dedicated to the regulation of food intake in order to meet the physiological needs of the body. A strict regulation at the physiological level is maintained by the central nervous system which controls the energy homeostasis and peripheral organs involved in food intake, and energy storage and expenditure. Nonetheless, eating, to a large extent, is influenced by social and emotional cues which are largely dependent on the socio-economic context and the familial environment. It is now admitted that the early environment plays a major role in the establishment of feeding behavior both at the physiological and psychological levels. Among environmental parameters, early nutrition, including maternal nutrition before and during pregnancy and during lactation, and infant nutrition during the first months and years of life are essential for a normal fetal development and for an optimal setting up of the complex physiological interactions that will drive food intake regulation throughout the life course. In the last few decades, evidence has been accumulating from both human cohort studies and experimental animal models that shed light on several biological mechanisms underlying this early influence. Important technological advances have allowed the identification of physiological and molecular mechanisms by which early experience, as early as during fetal life, may have long-term influence but may be reversible in a precise time-window. Knowledge in the field of nutritional programming is progressing but faces difficulties associated with the high complexity and interaction between many parameters belonging to various fields spanning physiology, metabolism,and also psychology and sociology

Early life nutrition and long term appetite regulation

International audienceFeeding behavior is a complex trait dedicated to the regulation of food intake in order to meet the physiological needs of the body. A strict regulation at the physiological level is maintained by the central nervous system which controls the energy homeostasis and peripheral organs involved in food intake, and energy storage and expenditure. Nonetheless, eating, to a large extent, is influenced by social and emotional cues which are largely dependent on the socio-economic context and the familial environment. It is now admitted that the early environment plays a major role in the establishment of feeding behavior both at the physiological and psychological levels. Among environmental parameters, early nutrition, including maternal nutrition before and during pregnancy and during lactation, and infant nutrition during the first months and years of life are essential for a normal fetal development and for an optimal setting up of the complex physiological interactions that will drive food intake regulation throughout the life course. In the last few decades, evidence has been accumulating from both human cohort studies and experimental animal models that shed light on several biological mechanisms underlying this early influence. Important technological advances have allowed the identification of physiological and molecular mechanisms by which early experience, as early as during fetal life, may have long-term influence but may be reversible in a precise time-window. Knowledge in the field of nutritional programming is progressing but faces difficulties associated with the high complexity and interaction between many parameters belonging to various fields spanning physiology, metabolism,and also psychology and sociology

Structure, expression et polymorphisme du gène PRKAG3 bovin (implication dans le métabolisme musculaire et la qualité de la viande)

Le gène PRKAG3 code l isoforme g3 d une sous-unité régulatrice de l'enzyme AMPK (AMP dependant Protein Kinase), cette kinase étant l un des principaux médiateurs de la régulation du métabolisme des sucres et acides gras dans le muscle. Le gène PRKAG3 bovin a été entièrement séquencé et sa structure établie. Nous avons mis en évidence une très grande variabilité au niveau de la séquence du gène et de la population de transcrits. 46 polymorphismes de type SNPs ont été identifiés, six d entre eux entraînent un changement dans la séquence protéique. L analyse des transcrits a montré l existence de transcrits alternatifs générés par des mécanismes d épissage jamais observés chez le porc ou dans d autres espèces. Ces transcrits, correspondant à des formes plus longues de l ARNm, sont retrouvés chez tous les animaux et présentent un taux de transcription plus faible que les transcrits standards de ce gène. Une étude préliminaire visant à explorer la variabilité phénotypique des caractéristiques des viandes en comparaison avec le génotype des animaux a montré que l un des polymorphismes serait associé statistiquement avec le taux de glycogène. Nous avons également pu mettre en évidence que l un des polymorphismes du gène PRKAG3 est associé à une augmentation du taux de transcrits, suggérant une régulation de la transcription différente en fonction des allèles. Les 6 autres gènes codant les différentes isoformes des différentes sous-unités du complexe enzymatique ont également été caractérisés et leur polymorphisme étudié. Un taux beaucoup plus faible de polymorphisme a été détecté sur ces autres gènes, comparativement au nombre observé pour le gène PRKAG3. Une analyse quantitative des transcrits des différents gènes codant pour toutes les sous-unités de l AMPK a été réalisée. Celle-ci nous a permis de confirmer que le transcrit du gène PRKAG3 est préférentiellement exprimé dans le muscle squelettique, l expression des transcrits des autres gènes étant plus ubiquitaire. La qualité d une viande est également due à une composante lipidique dans le muscle. L étude des transcrits du gène PPARG bovin a révélé l existence d un mécanisme complexe d épissage intergénique, en plus des mécanismes habituels. Celui-ci conduit à deux types de transcrits chimères entre le gène PPARG et le gène voisin TSEN2. La présence d une protéine chimère n a pu être mise en évidence dans les tissus bovins, cependant cette protéine a pu être produite par expression transitoire dans des cellules de mammifère.The PRKAG3 gene encodes the g3 isoform of a regulating sub-unit of AMPK (AMP dependent Protein Kinase) enzyme, this kinase is one of the principal mediators of the metabolism regulation of sugars and fatty acids in muscle. The bovine PRKAG3 gene was entirely sequenced and its structure established. We have identified an important variability in this gene, 46 SNPs polymorphisms were identified and six of them result in a change in the amino-acid sequence. We demonstrated the existence of alternative transcripts resulting from splicing mechanisms never observed in the pig or in other species. These longer transcripts are found in all the animals, and show a transcription rate weaker than standard ones of this gene. A preliminary association study between the phenotypic characteristics of meat and the animals genotype showed that one of these polymorphisms is statistically associated with the glycogen content. We could also highlight that one of the PRKAG3 gene polymorphisms is associated with an increase in the expression level, suggesting a transcription regulation that might differ from one allele to another. The six other genes encoding the differents sub-units isoforms of the AMPK complex were also characterized and screened for polymorphism. A lower level of polymorphism was detected in these genes, compared to the PRKAG3 gene. Quantitative analysis of all AMPK bovine transcripts showed that PRKAG3 is preferentially expressed in skeletal muscle whereas the other genes have an ubiquitous expression. Meat quality is also due to lipidic composition in muscle. The analysis of bovine PPARG transcripts have revealed, in addition to normal transcripts, a complex intergenic splicing mechanism, leading to two chimeric transcripts involving the PPARG gene and the neighbouring gene TSEN2. The putative chimeric protein could not be detected in bovine tissues, however this protein was transitory expressed in mammalian cells.LIMOGES-BU Sciences (870852109) / SudocSudocFranceF

Protein and methyl donors in maternal diet during preconceptual period, gestation and lactation affect fetal and postnatal growth, energy metabolism and gene expression in the offspring

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