Vergleichende Analyse der TSE-assoziierten Genexpression in ausgewählten Geweben von Tieren mit unterschiedlicher genetischer Prädisposition für die Ausprägung von Scrapie beim Schaf

Auf Basis vergleichender Expressionsanalyse des Schaftranskriptoms sollen mögliche physiologische Eigenschaften einer differenten Scrapie-Empfindlichkeit (PRNP-Genotypen der Risikoklasse R1 vs. R5) aufgeklärt werden. Von gesunden, nicht infizierten Texelschafen beider Risikoklassen wurden fünf Gewebe mittels Microarray-Hybridisierungstechnik vergleichend untersucht. Im retropharyngealen Lymphknoten wurden 336 signifikante different exprimiert Gene zwischen den Texelschafen der Risikoklassen R1 und R5 beobachtet. Dabei zeigten die scrapieresistenten Tiere (R1) eine Aufregulation der Genexpression in den Stoffwechselwegen Immunantwort und Reaktion auf Pathogene.The present study identifies pathways differentially expressed between healthy, non-infected Texel sheep of PRNP variants representing scrapie susceptibility classes R1 and R5. Comparative expression profiling was carried out in the four tissues of prion infection route and the metabolic active liver. A global sheep transcriptom analyses were done by cross-species hybridization on "human 10k array". Gene expression pattern of retropharyngeal lymph nodes exhibit differentially expressed genes between non-infected, healthy R1 and R5 sheep. Scrapie-resistant animals (R1) showed increased number of genes within the biological processes of immune response and response to pathogens

Agouti Revisited: Transcript Quantification of the ASIP Gene in Bovine Tissues Related to Protein Expression and Localization

Beside its role in melanogenesis, the agouti signaling protein (ASIP) has been related to obesity. The potentially crucial role in adipocyte development makes it a tempting candidate for economic relevant, fat related traits in farm animals. The objective of our study was to characterize the mRNA expression of different ASIP transcripts and of putative targets in different bovine tissues, as well as to study consequences on protein abundance and localization. ASIP mRNA abundance was determined by RT-qPCR in adipose and further tissues of cattle representing different breeds and crosses. ASIP mRNA was up-regulated more than 9-fold in intramuscular fat of Japanese Black cattle compared to Holstein (p<0.001). Further analyses revealed that a transposon-derived transcript was solely responsible for the increased ASIP mRNA abundance. This transcript was observed in single individuals of different breeds indicating a wide spread occurrence of this insertion at the ASIP locus in cattle. The protein was detected in different adipose tissues, skin, lung and liver, but not in skeletal muscle by Western blot with a bovine-specific ASIP antibody. However, the protein abundance was not related to the observed ASIP mRNA over-expression. Immuno-histochemical analyses revealed a putative nuclear localization of ASIP additionally to the expected cytosolic signal in different cell types. The expression of melanocortin receptors (MCR) 1 to 5 as potential targets for ASIP was analyzed by RT-PCR in subcutaneous fat. Only MC1R and MC4R were detected indicating a similar receptor expression like in human adipose tissue. Our results provide evidence for a widespread expression of ASIP in bovine tissues at mRNA and, for the first time, at protein level. ASIP protein is detectable in adipocytes as well as in further cells of adipose tissue. We generated a basis for a more detailed investigation of ASIP function in peripheral tissues of various mammalian species

Increased expression of thyroid hormone responsive protein (THRSP) is the result but not the cause of higher intramuscular fat content in cattle

Thyroid hormone responsive protein (THRSP) is known to be involved in lipogenic processes in rodents. In cattle, THRSP could be a potential molecular marker for intramuscular fat (IMF) deposition since mRNA abundance was frequently found to be increased in skeletal muscle with high IMF content compared to those with low IMF. The aim of this study was to elucidate the background of this differential expression and to evaluate the role of THRSP as candidate for increased IMF content in cattle. By combination of mRNA and protein analyses, we could demonstrate that THRSP is present mainly in nuclei of adipose tissue, in intramuscular fat cells and associated cells, and in cells of the portal triad of liver, whereas muscle cells did not express THRSP. Cell culture analyses revealed furthermore that THRSP is expressed in mature adipocytes rather than in early stages of adipogenesis. Collectively, our data support the putative role of THRSP as transcriptional regulator and demonstrate that an increased expression of THRSP in M. longissimus is a consequence of but not the reason for a higher number of intramuscular adipocytes in cattle with enhanced IMF deposition

Molecular Heterogeneities of Adipose Depots - Potential Effects on Adipose-Muscle Cross-Talk in Humans, Mice and Farm Animals

Adipose tissue is considered as a major endocrine organ that secretes numerous proteins called adipokines. The heterogeneous nature of adipose tissue in different parts of the body suggests respective heterogeneity of proteomes and secretomes. This review consolidates knowledge from recent studies targeting the diversity of different adipose depots affecting the pattern of secreted adipokines and discusses potential consequences for the cross-talk between adipose and skeletal muscle in humans, rodent models and farm animals. Special attention is paid to muscle-associated fat depots like inter- and intramuscular fat that become focus of attention in the context of the rather new notion of skeletal muscle as a major endocrine organ. Understanding the complexity of communication between adipocytes and skeletal muscle cells will allow developing strategies for improvement of human health and for sustainable production of high quality meat

Differentially Expressed miRNA-Gene Targets Related to Intramuscular Fat in Musculus Longissimus Dorsi of Charolais × Holstein F2-Crossbred Bulls

Intramuscular fat (IMF) is a meat quality indicator associated with taste and juiciness. IMF deposition, influenced by genetic and non-genetic factors, occurs through a transcriptionally coordinated process of adipogenesis. MicroRNAs (miRNAs) are transcriptional regulators of vital biological processes, including lipid metabolism and adipogenesis. However, in bovines, limited data on miRNA profiling and association with divergent intramuscular fat content, regulated exclusively by genetic parameters, have been reported. Here, a microarray experiment was performed to identify and characterize the miRNA expression pattern in the Musculus longissimus dorsi of F2-cross (Charolais &times; German Holstein) bulls with high and low IMF. A total of 38 differentially expressed miRNAs (DE miRNAs), including 33 upregulated and 5 downregulated (corrected p-value &le; 0.05, FC &ge; &plusmn;1.2), were reported. Among DE miRNAs, the upregulated miRNAs miR-105a/b, miR-695, miR-1193, miR-1284, miR-1287-5p, miR-3128, miR-3178, miR-3910, miR-4443, miR-4445 and miR-4745, and the downregulated miRNAs miR-877-5p, miR-4487 and miR-4706 were identified as novel fat deposition regulators. DE miRNAs were further analyzed, along with previously identified differentially expressed genes (DEGs) from the same samples and predicted target genes, using multiple bioinformatic approaches, including target prediction tools and co-expression networks, as well as Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. We identified DE miRNAs and their gene targets associated with bovine intramuscular adipogenesis, and we provide a basis for further functional investigations

Transcriptome profiling of Musculus longissimus dorsi in two cattle breeds with different intramuscular fat deposition

Intramuscular fat (IMF) deposition is a physiological process in cattle and is highly variable among breeds suggesting a large influence of genetic factors besides environmental factors. In order to elucidate molecular pathways underlying the genetic variation in this trait we compared transcriptomes of Musculus longissimus dorsi (MLD) in steers of Japanese Black and Holstein Friesian cattle breeds fed a high energy diet typically applied in Japan to achieve maximum IMF content. We identified a total of 569 differentially expressed genes (DEGs) with the majority (433) up-regulated in Japanese Black cattle. This breed is characterized by an extreme capacity for IMF deposition. Subsequent Ingenuity Pathway Analysis (IPA) revealed a gene network linking parameters of cell morphology and maintenance with lipid metabolism. The data from this study were deposited in NCBI's Gene Expression Omnibus and are accessible through GEO Series accession number GSE75348. We provide here a dataset which is of potential value to dissect molecular pathways influencing differences in fat deposition under high-energy nutrition. Keywords: Cattle, Japanese Black, Holstein Friesian, Intramuscular fat, Musculus longissimus dorsi, Microarra

Differentially Expressed miRNA-Gene Targets Related to Intramuscular Fat in Musculus Longissimus Dorsi of Charolais × Holstein F2-Crossbred Bulls

Intramuscular fat (IMF) is a meat quality indicator associated with taste and juiciness. IMF deposition, influenced by genetic and non-genetic factors, occurs through a transcriptionally coordinated process of adipogenesis. MicroRNAs (miRNAs) are transcriptional regulators of vital biological processes, including lipid metabolism and adipogenesis. However, in bovines, limited data on miRNA profiling and association with divergent intramuscular fat content, regulated exclusively by genetic parameters, have been reported. Here, a microarray experiment was performed to identify and characterize the miRNA expression pattern in the Musculus longissimus dorsi of F2-cross (Charolais × German Holstein) bulls with high and low IMF. A total of 38 differentially expressed miRNAs (DE miRNAs), including 33 upregulated and 5 downregulated (corrected p-value ≤ 0.05, FC ≥ ±1.2), were reported. Among DE miRNAs, the upregulated miRNAs miR-105a/b, miR-695, miR-1193, miR-1284, miR-1287-5p, miR-3128, miR-3178, miR-3910, miR-4443, miR-4445 and miR-4745, and the downregulated miRNAs miR-877-5p, miR-4487 and miR-4706 were identified as novel fat deposition regulators. DE miRNAs were further analyzed, along with previously identified differentially expressed genes (DEGs) from the same samples and predicted target genes, using multiple bioinformatic approaches, including target prediction tools and co-expression networks, as well as Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. We identified DE miRNAs and their gene targets associated with bovine intramuscular adipogenesis, and we provide a basis for further functional investigations

Characterization of animals and number of tissue and DNA samples.

<p>MLD: M. longissimus, IMF: intramuscular fat, IRMF: intermuscular fat, SCF: subcutaneous fat.</p

Locus Characterization and Gene Expression of Bovine FNDC5: Is the Myokine Irisin Relevant in Cattle?

The transmembrane protein FNDC5 was recently characterized as precursor of an exercise induced myokine named irisin. Previous studies found a relationship between circulating irisin levels and muscle mass in humans. Consequently, we tested the hypothesis whether FNDC5/irisin is involved in the modulation of body composition in cattle. Since information on the bovine FNDC5 locus was scarce, we characterized the gene experimentally as prerequisite for these investigations. We provide here a revised and extended gene model for bovine FNDC5. Although similarly organized like the human and murine loci, a higher variability was observed at transcript level in the bovine locus. FNDC5 mRNA was abundant in bovine skeletal muscle and was detected at lower levels in adipose tissue and liver. There were no expression differences between two groups of bulls highly different in muscularity and adiposity. Full-length FNDC5 protein (25 kDa) was present in bovine skeletal muscle independent of muscularity. Neither FNDC5 nor its putatively secreted peptide irisin were found in circulation of bulls. In contrast, we demonstrated that FNDC5 (25 kDa) and irisin (12 kDa) were present in murine skeletal muscle and that irisin was circulating in murine serum. This indicates fundamental differences in the regulation of FNDC5 and irisin between rodents and cattle

Gene expression profile of Musculus longissimus dorsi in bulls of a Charolais × Holstein F2-cross with divergent intramuscular fat content

Transcriptomes of Musculus longissimus dorsi (MLD) were compared between bulls from a F2-cross derived from Charolais and Holstein Friesian. Two groups of 10 bulls were selected which differed significantly in intramuscular fat (IMF) deposition despite standardized husbandry and feeding conditions and identical sires in both groups. Consequently, genetic factors underlying the different capability of IMF deposition should be identified. A total of 32 differentially expressed genes (DEGs) were found of which 11 were up-regulated and 21 were down-regulated in the high IMF group. Ingenuity Pathway Analysis (IPA) identified a gene network comprising DEGs with functions in carbohydrate metabolism, lipid metabolism and molecular transport. The data from this study were deposited in NCBI's Gene Expression Omnibus and are accessible through GEO Series accession number GSE75347. We provide here a dataset which is of potential value to dissect molecular pathways influencing differences in IMF deposition in crossbred cattle with standardized genetic background. Keywords: Cattle, Charolais, Holstein, Intramuscular fat, Musculus longissimus dorsi, Microarra