Impact of periconceptional and preimplantation undernutrition on factors regulating myogenesis and protein synthesis in muscle of singleton and twin fetal sheep

Maternal intake restriction programs the energy metabolism, clock circadian regulator and mTOR signals in the skeletal muscles of goat offspring probably via the protein kinase A-cAMP-responsive element-binding proteins pathway

The biological mechanism by which maternal undernutrition increases the metabolic disorder risk of skeletal muscles in offspring is not fully understood. We hypothesize that maternal intake restriction influences metabolic signals in the skeletal muscles of offspring via a glucagon-mediated pathway. Twenty-four pregnant goats were assigned to the control group (100% of the nutrients requirement, n = 12) and restricted group (60% of the control feed allowance from pregnant days 45 to 100, n = 12). Blood and L ongissimus thoracis muscle were sampled from dams (100 d of gestation), fetuses (100 d of gestation), and kids (90 d after birth) in each group. The data were analyzed using the linear MIXED model, with the multiple comparison method of SIDAK applied. Intake restriction reduced (P < 0.05) the total blood protein of dams and fetuses. Maternal restriction decreased (P < 0.05) the cAMP-responsive element-binding protein 1 (CREB1), CREB-binding protein (CREBBP), protein kinase A (PKA), aryl hydrocarbon receptor nuclear translocator-like protein 1 (BMAL1), protein kinase B (AKT1), mammalian target of rapamycin (mTOR), and regulatory-associated protein of mTOR (RPTOR) mRNA expression in the fetuses, and reduced (P < 0.05) the CREBBP, nuclear receptor subfamily 1 group H member 3 (NR1H3), D-box binding PAR bZIP transcription factor (DBP) and PKA mRNA levels in the kids, but increased (P < 0.05) the peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC1 A) and tuberous sclerosis 2 (TSC2) mRNA levels in the fetuses. The mRNA expression of clock circadian regulator (CLOCK) and TSC2 genes was increased (P < 0.05) in the restricted kids. The protein expression of total PKA and phosphorylated PKA in the restricted fetuses and kids were downregulated (P < 0.05), and the protein expression of total mTOR and phosphorylated mTOR were reduced (P < 0.05) in the restricted fetuses and kids. Maternal intake restriction regulated fat oxidation, protein synthesis, and circadian clock expression in the muscles of the offspring probably via the glucagon-mediated PKA-CREB pathway, which reveals a noteworthy molecular pathway that maternal undernutrition leads to metabolic adaptation of skeletal muscle in offspring.

MicroRNA-27b-3p Targets the Myostatin Gene to Regulate Myoblast Proliferation and Is Involved in Myoblast Differentiation

microRNAs play an important role in the growth and development of chicken embryos, including the regulation of skeletal muscle genesis, myoblast proliferation, differentiation, and apoptosis. Our previous RNA-seq studies showed that microRNA-27b-3p (miR-27b-3p) might play an important role in regulating the proliferation and differentiation of chicken primary myoblasts (CPMs). However, the mechanism of miR-27b-3p regulating the proliferation and differentiation of CPMs is still unclear. In this study, the results showed that miR-27b-3p significantly promoted the proliferation of CPMs and inhibited the differentiation of CPMs. Then, myostatin (MSTN) was confirmed to be the target gene of miR-27b-3p by double luciferase reporter assay, RT-qPCR, and Western blot. By overexpressing and interfering with MSTN expression in CPMs, the results showed that overexpression of MSTN significantly inhibited the proliferation and differentiation of CPMs. In contrast, interference of MSTN expression had the opposite effect. This study showed that miR-27b-3p could promote the proliferation of CPMs by targeting MSTN. Interestingly, both miR-27b-3p and MSTN can inhibit the differentiation of CPMs. These results provide a theoretical basis for further understanding the function of miR-27b-3p in chicken and revealing its regulation mechanism on chicken muscle growth.

Transcriptomic profile of semitendinosus muscle of bulls of different breed and performance

The aim of the study was to compare the transcriptomic profiles of fully differentiated skeletal muscle derived from bulls belonging to different breeds of varying performance. Microarray analyses were performed to determine the differences in the expression profiles of genes between semitendinosus muscles of 15-month-old beef-breed bulls (Limousin—LIM and Hereford—HER) and dairy-breed bulls (Holstein Friesian—HF). These analyses allowed for the identification of those genes the expression of which is similar and characteristic of fully differentiated muscle in beef breeds, but differs in skeletal muscle of a typical dairy breed. The analysis revealed 463 transcripts showing similar expression in the semitendinosus muscle of beef breeds (LIM/HER), in comparison with the dairy breed (HF). Among the identified genes, 227 were upregulated and 236 were downregulated in beef breeds. The ontological analyses revealed that the largest group of genes similarly expressed in LIM and HER was involved in the processes of protein metabolism and development of muscle organ. In beef breeds, some genes involved in protein synthesis and proteolysis showed an upregulation, including ctsd, ctsf, fhl2, fhl3, fst, sirt1, and trim63, whereas some were downregulated, including bmpr1a, bmpr2, mstn, smad2, hspa8, gsk3β, and tgfβ2. The expression of the chosen genes was confirmed by RT-qPCR technique. Thus, it can be assumed that the identified genes involved in the regulation of growth and development of muscle tissue and the processes of protein metabolism in the examined cattle breeds may be responsible for the greater gain of muscle mass in beef-breed bulls.

A Map of the microRNA Regulatory Networks Identified by Experimentally Validated microRNA-Target Interactions in Five Domestic Animals: Cattle, Pig, Sheep, Dog, and Chicken

Domestic animals are members of the broader ecological context, in which humans are situated. Yet, genomics and systems science research have lagged behind and been relatively underappreciated in domestic animals compared to human genetics/genomics. Harnessing big data calls for omics data mapping studies in a broad range of mammals. To this end, microRNAs (miRNAs) regulate posttranscriptional expression of target genes, hence, governing different biological pathways and physiological processes. The knowledge of miRNA regulatory networks and maps is important for understanding regulation of gene expression and functions in both humans and domestic animals. However, complete miRNA regulatory networks have not yet been described in all species, particularly in domestic animals. We report here an original analysis so as to map the miRNA regulatory networks in domestic animals based on miRNA-target interactions (MTIs). Validated MTIs for five species; cattle, pig, sheep, dog, and chicken were extracted from the miRTarBase. miRNA regulomes were visualized using the Cytoscape software. The data in cattle, chicken, and pig were sufficient to visualize networks, identify central molecules, and subnetworks associated with the same phenotype; however, the MTI data in dog and sheep are still limited. We found several hub genes with large number of interactions, for example, 1 miRNA (bta-miR-17-5p) interacting with 27 genes and 7 miRNAs interacting with the same gene (tumor necrosis factor [TNF]) in cattle. In addition, two single-nucleotide polymorphisms were identified within the seed region of a previously demonstrated MTI, namely, between HMGB3 (high mobility group box 3) gene and bta-miR-17-5p. In summary, this miRNA regulome mapping study will enable and guide further studies of genome function in mammals with a view to applications in human as well as veterinary medicine. Furthermore, these miRNA regulomes can help to clarify fundamental pathways in cell biology and reveal molecular insights on phenotypic trait variability in common complex diseases and response phenotypes of drugs or other health interventions for precision medicine in the future.

Bioinformatic gene analysis for potential biomarkers and therapeutic targets of atrial fibrillation-related stroke

BACKGROUND

Atrial fibrillation (AF) is one of the most prevalent sustained arrhythmias, however, epidemiological data may understate its actual prevalence. Meanwhile, AF is considered to be a major cause of ischemic strokes due to irregular heart-rhythm, coexisting chronic vascular inflammation, and renal insufficiency, and blood stasis. We studied co-expressed genes to understand relationships between atrial fibrillation (AF) and stroke and reveal potential biomarkers and therapeutic targets of AF-related stroke.

METHODS

AF-and stroke-related differentially expressed genes (DEGs) were identified via bioinformatic analysis Gene Expression Omnibus (GEO) datasets GSE79768 and GSE58294, respectively. Subsequently, extensive target prediction and network analyses methods were used to assess protein-protein interaction (PPI) networks, Gene Ontology (GO) terms and pathway enrichment for DEGs, and co-expressed DEGs coupled with corresponding predicted miRNAs involved in AF and stroke were assessed as well.

RESULTS

We identified 489, 265, 518, and 592 DEGs in left atrial specimens and cardioembolic stroke blood samples at < 3, 5, and 24 h, respectively. LRRK2, CALM1, CXCR4, TLR4, CTNNB1, and CXCR2 may be implicated in AF and the hub-genes of CD19, FGF9, SOX9, GNGT1, and NOG may be associated with stroke. Finally, co-expressed DEGs of ZNF566, PDZK1IP1, ZFHX3, and PITX2 coupled with corresponding predicted miRNAs, especially miR-27a-3p, miR-27b-3p, and miR-494-3p may be significantly associated with AF-related stroke.

CONCLUSION

AF and stroke are related and ZNF566, PDZK1IP1, ZFHX3, and PITX2 genes are significantly associated with novel biomarkers involved in AF-related stroke.

Maternal undernutrition during the pre- and post-conception periods in twin-bearing hairsheep ewes: effects on fetal and placental development at mid-gestation

To evaluate the effects of pre- and post-conception undernutrition (UN) on fetal and placental development at mid-gestation, 28 Katahdin × Pelibuey multiparous ewes were blocked by weight and assigned to the following four dietary treatments (n = 7 each): ewes fed 100% (control) or 60% of their nutritional requirements 30 days before mating (UNPre), 50 days after mating (UNPost) or during both periods (UNB). Four twin-bearing ewes were selected per treatment at day 50 post-conception and then slaughtered at day 75 of gestation to analyze their fetuses. Control fetuses were heavier (P < 0.05) than UNPost and UNB fetuses in 14.6 and 9.4%, respectively. Organ weights as percentage of the fetal weight (except for liver) and morphometric measurements (except for abdominal girth) were similar between control and UN fetuses (UNPre, UNPost, and UNB). Placental mass was heavier (P < 0.05) in control ewes than UNB ewes, but not relative to ewes of other treatments. The number of placentomes per ewe and placental efficiency were unaffected by UN treatments. Compared to control, only UNB ewes exhibited variations (P < 0.05) in the proportion of placentomes, specifically for type A (+13.8%) and B (-12.6%). Placentomes of type A and B had lower weight, length, and width of placentas in UNPost and UNB ewes than placentas of control ewes (P < 0.05). Overall results indicate that fetal and placental development of ewes carrying twins is mainly altered when nutritional restriction occurs simultaneously before conception and during the first third of pregnancy.

Reduced fetal vitamin D status by maternal undernutrition during discrete gestational windows in sheep

Placental transport of vitamin D and other nutrients (e.g. amino acids, fats and glucose) to the fetus is sensitive to maternal and fetal nutritional cues. We studied the effect of maternal calorific restriction on fetal vitamin D status and the placental expression of genes for nutrient transport [aromatic T-type amino acid transporter-1 (TAT-1); triglyceride hydrolase/lipoprotein uptake facilitator lipoprotein lipase (LPL)] and vitamin D homeostasis [CYP27B1; vitamin D receptor (VDR)], and their association with markers of fetal cardiovascular function and skeletal muscle growth. Pregnant sheep received 100% total metabolizable energy (ME) requirements (control), 40% total ME requirements peri-implantation [PI40, 1-31 days of gestation (dGA)] or 50% total ME requirements in late gestation (L, 104-127 dGA). Fetal, but not maternal, plasma 25-hydroxy-vitamin D (25OHD) concentration was lower in PI40 and L maternal undernutrition groups (P<0.01) compared with the control group at 0.86 gestation. PI40 group placental CYP27B1 messenger RNA (mRNA) levels were increased (P<0.05) compared with the control group. Across all groups, higher fetal plasma 25OHD concentration was associated with higher skeletal muscle myofibre and capillary density (P<0.05). In the placenta, higher VDR mRNA levels were associated with higher TAT-1 (P<0.05) and LPL (P<0.01) mRNA levels. In the PI40 maternal undernutrition group only, reduced fetal plasma 25OHD concentration may be mediated in part by altered placental CYP27B1. The association between placental mRNA levels of VDR and nutrient transport genes suggests a way in which the placenta may integrate nutritional cues in the face of maternal dietary challenges and alter fetal physiology.

The effect of maternal nutrition level during the periconception period on fetal muscle development and plasma hormone concentrations in sheep

The effect of maternal nutrition level during the periconception period on the muscle development of fetus and maternal-fetal plasma hormone concentrations in sheep were examined. Estrus was synchronized in 55 Karayaka ewes and were either fed ad libitum (well-fed, WF, n=23) or 0.5×maintenance (under-fed, UF, n=32) 6 days before and 7 days after mating. Non-pregnant ewes (WF, n=13; UF, n=24) and ewes carrying twins (WF, n=1) and female (WF, n=1; UF, n=3) fetuses were removed from the experiment. The singleton male fetuses from well-fed (n=8) and under-fed (n=5) ewes were collected on day 90 of gestation and placental characteristics, fetal BWs and dimensions, fetal organs and muscles weights were recorded. Maternal (on day 7 after mating) and fetal (on day 90 of pregnancy) blood samples were collected to analyze plasma hormone concentrations. Placental characteristics, BW and dimensions, organs and muscles weights of fetuses were not affected by maternal feed intake during the periconception period. Maternal nutrition level did not affect fiber numbers and the muscle cross-sectional area of the fetal longissimus dorsi (LD), semitendinosus (ST) muscles, but the cross-sectional area of the secondary fibers in the fetal LD and ST muscles from the UF ewes were higher than those from the WF ewes (P<0.05). Also, the ratio of secondary to primary fibers in the ST muscle were tended to be lower in the fetuses from the UF ewes (P=0.07). Maternal nutrition level during the periconception period did not cause any significant changes in fetal plasma insulin and maternal and fetal plasma IGF-I, cortisol, progesterone, free T3 and T4 concentrations. However, maternal cortisol concentrations were lower while insulin concentrations were higher in the WF ewes than those in the UF ewes (P<0.05). These results indicate that the reduced maternal feed intake during the periconception period may alter muscle fiber diameter without affecting fiber types, fetal weights and organ developments and plasma hormone concentrations in the fetus.

A review of fundamental principles for animal models of DOHaD research: an Australian perspective

Epidemiology formed the basis of ‘the Barker hypothesis’, the concept of ‘developmental programming’ and today’s discipline of the Developmental Origins of Health and Disease (DOHaD). Animal experimentation provided proof of the underlying concepts, and continues to generate knowledge of underlying mechanisms. Interventions in humans, based on DOHaD principles, will be informed by experiments in animals. As knowledge in this discipline has accumulated, from studies of humans and other animals, the complexity of interactions between genome, environment and epigenetics, has been revealed. The vast nature of programming stimuli and breadth of effects is becoming known. As a result of our accumulating knowledge we now appreciate the impact of many variables that contribute to programmed outcomes. To guide further animal research in this field, the Australia and New Zealand DOHaD society (ANZ DOHaD) Animals Models of DOHaD Research Working Group convened at the 2nd Annual ANZ DOHaD Congress in Melbourne, Australia in April 2015. This review summarizes the contributions of animal research to the understanding of DOHaD, and makes recommendations for the design and conduct of animal experiments to maximize relevance, reproducibility and translation of knowledge into improving health and well-being.