Transcriptomic Profiling During Myogenesis

Does β-Hydroxy-β-Methylbutyrate Have Any Potential to Support the Treatment of Duchenne Muscular Dystrophy in Humans and Animals?

Skeletal muscle is the protein reservoir of our body and an important regulator of glucose and lipid homeostasis. The dystrophin gene is the largest gene and has a key role in skeletal muscle construction and function. Mutations in the dystrophin gene cause Duchenne and Becker muscular dystrophy in humans, mice, dogs, and cats. Duchenne muscular dystrophy (DMD) is an X-linked neuromuscular condition causing progressive muscle weakness and premature death. β-hydroxy β-methylbutyrate (HMB) prevents deleterious muscle responses under pathological conditions, including tumor and chronic steroid therapy-related muscle losses. The use of HMB as a dietary supplement allows for increasing lean weight gain; has a positive immunostimulatory effect; is associated with decreased mortality; and attenuates sarcopenia in elderly animals and individuals. This study aimed to identify some genes, metabolic pathways, and biological processes which are common for DMD and HMB based on existing literature and then discuss the consequences of that interaction.

RNA-seq Based Transcriptome Analysis of the Anti-Obesity Effect of Green Tea Extract Using Zebrafish Obesity Models

Green tea is a popular beverage that is rich in polyphenolic compounds such as catechins. Its major content, (-)-epigallocatechin-3-gallate, has been shown to have beneficial effects on several diseases including cancer, metabolic syndrome, cardiovascular diseases, and neurodegenerative diseases. The aim of this study was to assess the anti-obesity effects and the underlying molecular mechanisms of green tea extract (GTE) using zebrafish larva and adult obesity models. We administered 100 μg/mL GTE to zebrafish larvae and performed a short-term obesogenic test. GTE significantly decreased the visceral adipose tissue volume induced by a high-fat diet. Oral administration (250 µg/g body weight/day) of GTE to adult diet-induced obese zebrafish also significantly reduced their visceral adipose tissue volume, with a reduction of plasma triglyceride and total cholesterol levels. To investigate the molecular mechanism underlying the GTE effects, we conducted RNA sequencing using liver tissues of adult zebrafish and found that GTE may ameliorate the obese phenotypes via the activation of Wnt/β-catenin and adenosine monophosphate-activated protein kinase (AMPK) pathway signaling. In addition, the comparative transcriptome analysis revealed that zebrafish and mammals may share a common molecular response to GTE. Our findings suggest that daily consumption of green tea may be beneficial for the prevention and treatment of obesity.

An Optimized Method of RNA Isolation from Goat Milk Somatic Cells for Transcriptomic Analysis

The goat (Capra hircus) is a perfect animal model for analyzing the transcriptome of milk somatic cells (MSCs), as sufficient numbers of somatic cells in goat milk, i.e., exfoliated epithelial cells, can be obtained using noninvasive methods. RNA integrity and purity are the first and most important parameters qualifying samples for transcriptomic tests and next-generation sequencing, as RNA quality influences experimental results. The aim of this study was to optimize a method for obtaining high-quality RNA from goat MSCs, irrespective of effects like breed, lactation stage, health status (e.g., with or without small ruminant lentivirus [SRLV] infection), or number of somatic cells. Milk samples were obtained from goats of two Polish breeds in various lactation stages and in different parities, and from goats infected and not infected with SRLV. Altogether, 412 MSC samples were examined: 206 using method A with fenozol and 206 using method B with QIAzol. Though the overall purity (measured as absorbance ratios at 260 nm/280 nm and 260 nm/230 nm) of the RNA material was comparable, the average yield of RNA isolated using method A was 11.9 µg, while method B’s average yield was 29.9 µg. Moreover, method B resulted in good quality RNA suitable for transcriptome analysis. Results were confirmed by RT-qPCR, using 18S rRNA and RPLP0 as the reference genes. The application of our modified treatment method was successful in obtaining high-integrity samples for transcriptomic or next-generation sequencing analysis. Using a 400 mL milk sample cooled in ice directly after milking, securing the cooling chain process from milking to MSC isolation, and applying method B to isolate RNA, we obtained good RNA quality irrespective of the goats’ breed, lactation stage, parity, milk yield, SRLV infection, and even milk yield and number of somatic cells in milk.

Interleukin-8 enhances myocilin expression, Akt-FoxO3 signaling and myogenic differentiation in rat skeletal muscle cells

Interleukin (IL)-8 is released both in visceral adipose tissue and in contracting skeletal muscles. In this study, we examined cellular pathways associated with muscle hypertrophy, chosen on the basis of microRNA profiling, in differentiating rat primary skeletal muscle cells (RSkMC) treated with IL-8 (1 ng/ml) for 11 days. IL-8 increased myocilin expression, Akt phosphorylation, FoxO3 dispersion throughout the cytoplasm, and reduced FoxO3 level. IL-8 decreased the expression of atrogin and MuRF1 and increased myotube length and diameter. We concluded that IL-8 present in extracellular environment of myoblasts induced to differentiation stimulates expression of myocilin, a protein important for skeletal muscle hypertrophy. This phenomenon was associated with: (a) activation of myogenic transcription, (b) increased phosphorylation and activation of PKB/Akt, leading to (c) cytoplasm distribution and degradation of a transcription factor FoxO3, (d) decreased expression of gene markers of proteolysis, atrogin and Murf1, and (e) increased myotube length and diameter. In this regard, IL-8 affects skeletal muscle cells similarly to IGF-I and can be considered as a potent anticatabolic factor for skeletal muscle.