scholarly journals FNDC5 expression closely correlates with muscle fiber types in porcine longissimus dorsi muscle and regulates myosin heavy chains (MyHCs) mRNA expression in C2C12 cells

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11065
Author(s):  
Xiao-Ming Men ◽  
Zi-Wei Xu ◽  
Xin Tao ◽  
Bo Deng ◽  
Ke-Ke Qi
Keyword(s):  
Mrna Expression ◽  
Muscle Fiber ◽  
Small Interfering Rna ◽  
C2c12 Cells ◽  
Longissimus Dorsi ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Mrna Levels ◽  
Interfering Rna

Background Irisin (a glycosylated protein) is cleaved from fibronectin type III domain-containing protein 5 (FNDC5), which is expressed mainly in animal muscle tissues and has multiple metabolic regulatory activities. However, their roles in controlling myofiber types in skeletal muscle remain unclear. Methodology Two different commercial hybridized pigs, LJH (a crossed pig containing Chinese native pig genotypes) and DLY (Duroc × Landrace × Yorkshire) were selected to analyze FNDC5 mRNA expression and the mRNA composition of four adult myosin heavy chain (MyHC) isoforms (IIIaIIxIIb) in the longissimus dorsi (LD) muscle. C2C12 myoblasts were cultured to investigate the effects of FNDC5 on the four MyHCs mRNA expressive levels, using small interfering RNA for depletion and a eukaryotic expression vector carrying FNDC5 for overexpression. ZLN005 (a small molecule activator of FNDC5’s upstream control gene PGC1α) or recombinant human irisin protein were also used. Results In LD muscle, LJH pigs had the higher FNDC5 mRNA level, and MyHC I or IIa proportion than DLY pigs (P <  0.05). For C2C12 cells in vitro, small interfering RNA (si-592) silencing of FNDC5 expression markedly reduced MyHC IIa mRNA levels (P <  0.05), while FNDC5 overexpression significantly increased MyHC IIa mRNA levels (P <  0.05). Exogenous irisin increased the mRNA levels of PGC1α (peroxisome proliferator-activated receptor gamma coactivator 1-alpha), FNDC5, MyHCI, MyHCIIa, NRF1 (nuclear respiratory factor 1), VEGF (vascular endothelial growth factor), and TFAM (mitochondrial transcription factor A,) (P <  0.05), and the enzyme activities of SDH (succinate dehydrogenase), CK (creatine kinase), and MDH (malate dehydrogenase) in C2C12 myotubes (P <  0.05). These results showed that FNDC5 mRNA expression had a significant association with the characteristics of myofiber types in porcine muscle, and participated in regulating MyHCs mRNA expression of C2C12 myogenic differentiation cells in vitro. FNDC5 could be an important factor to control muscle fiber types, which provides a new direction to investigate pork quality via muscle fiber characteristics.

Strength, power, fiber types, and mRNA expression in trained men and women with different ACTN3 R577X genotypes

2009 ◽  
Vol 106 (3) ◽  
pp. 959-965 ◽  
Author(s):  
Barbara Norman ◽  
Mona Esbjörnsson ◽  
Håkan Rundqvist ◽  
Ted Österlund ◽  
Ferdinand von Walden ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Fiber ◽  
Fiber Type ◽  
Muscle Fiber Types ◽  
Vastus Lateralis Muscle ◽  
Fiber Types ◽  
Mrna Levels ◽  
Men And Women ◽  
Fiber Type Composition ◽  
Type Composition

α-Actinins are structural proteins of the Z-line. Human skeletal muscle expresses two α-actinin isoforms, α-actinin-2 and α-actinin-3, encoded by their respective genes ACTN2 and ACTN3. ACTN2 is expressed in all muscle fiber types, while only type II fibers, and particularly the type IIb fibers, express ACTN3. ACTN3 (R577X) polymorphism results in loss of α-actinin-3 and has been suggested to influence skeletal muscle function. The X allele is less common in elite sprint and power athletes than in the general population and has been suggested to be detrimental for performance requiring high power. The present study investigated the association of ACTN3 genotype with muscle power during 30-s Wingate cycling in 120 moderately to well-trained men and women and with knee extensor strength and fatigability in a subset of 21 men performing isokinetic exercise. Muscle biopsies were obtained from the vastus lateralis muscle to determine fiber-type composition and ACTN2 and ACTN3 mRNA levels. Peak and mean power and the torque-velocity relationship and fatigability output showed no difference across ACTN3 genotypes. Thus this study suggests that R577X polymorphism in ACTN3 is not associated with differences in power output, fatigability, or force-velocity characteristics in moderately trained individuals. However, repeated exercise bouts prompted an increase in peak torque in RR but not in XX genotypes, suggesting that ACTN3 genotype may modulate responsiveness to training. Our data further suggest that α-actinins do not play a significant role in determining muscle fiber-type composition. Finally, we show that ACTN2 expression is affected by the content of α-actinin-3, which implies that α-actinin-2 may compensate for the lack of α-actinin-3 and hence counteract the phenotypic consequences of the deficiency.

scholarly journals Characterization of GAB1 Expression Over the Menstrual Cycle in Women With and Without Polycystic Ovarian Syndrome Provides a New Insight Into Its Pathophysiology

2014 ◽  
Vol 99 (11) ◽  
pp. E2162-E2168 ◽  
Author(s):  
K. L. Roemer ◽  
S. L. Young ◽  
R. F. Savaris
Keyword(s):  
Menstrual Cycle ◽  
Protein Expression ◽  
Mrna Expression ◽  
Medroxyprogesterone Acetate ◽  
Small Interfering Rna ◽  
Polycystic Ovary ◽  
University Hospital ◽  
Ishikawa Cells ◽  
Interfering Rna

Context: In a previous microarray analysis, GRB2-associated binding protein 1 (GAB1), a docking protein closely related to the insulin receptor substrate, was down-regulated in endometrium of women with polycystic ovary syndrome (PCOS). Objective: The objective of the study was to characterize the cyclic expression of endometrial GAB1 in vivo in normal women and those with PCOS as well as investigate the possible mechanisms of endometrial regulation of GAB1 expression and action in vitro. Design: This was an experimental and case-control study. Setting: The study was conducted at a tertiary university hospital. Patients: Normal proven fertile women (controls; n = 31) and women with PCOS (cases; n = 26) participated in the study. Interventions: Interventions included timed endometrial biopsies at different phases of the menstrual cycle. Ishikawa cells were cultured with β-estradiol (E2), medroxyprogesterone acetate, and E2 + medroxyprogesterone acetate. Transfection of small interfering RNA for GAB1 in Ishikawa cells incubated with or without insulin. Main Outcome Measures: GAB1 mRNA expression in Ishikawa cells and in endometrium of cases and controls was measured. Protein expression of phosphorylated MAPK by Western blot was also measured. Immunohistochemical localization and expression of phosphorylated GAB1 in endometrium was also measured, using a digital histological score. Results: In endometrial tissue, GAB1 mRNA was reduced in the proliferative phase of PCOS women, compared with controls (P = .003; ANOVA). When all the phases of the menstrual cycle were grouped, GAB1 protein expression was reduced in endometrium of PCOS women (P &lt; .0001; Student t test). E2 increases GAB1 mRNA expression in Ishikawa cells (P = .001; ANOVA). Phosphorylated MAPK is reduced in cells transfected with small interfering RNA for GAB1 (P = .008; ANOVA) and incubated with insulin. Conclusions: GAB1 mRNA expression is positively modulated by E2. Endometrial GAB1 protein and mRNA expression are reduced in women with PCOS, suggesting that the endometrium of PCOS women have a defect in insulin signaling due to GAB1 down-regulation.

scholarly journals The continuum of hybrid IIX/IIB fibers in normal mouse muscles: MHC isoform proportions and spatial distribution within single fibers

2010 ◽  
Vol 299 (6) ◽  
pp. R1582-R1591 ◽  
Author(s):  
Min Yi Zhang ◽  
Wei Jie Zhang ◽  
Scott Medler
Keyword(s):  
Protein Content ◽  
Muscle Fiber ◽  
Normal Mouse ◽  
Relative Proportion ◽  
Longitudinal Distribution ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Mrna Levels ◽  
Single Fibers ◽  
Intermediate Phenotypes

Although skeletal muscle fiber types are often defined as belonging to discrete categories, many muscles possess fibers with intermediate phenotypes. These hybrid fiber types can be identified by their expression of two or more myosin heavy chain (MHC) isoforms within the same single fiber. In mouse muscles, the most common hybrid fibers are those coexpressing the IIX and IIB MHC isoforms. In the present study, we focused on these IIX/IIB fibers from normal mouse muscles to determine the relative proportions of MHC isoforms at both the protein and mRNA levels and to examine the longitudinal distribution of isoforms within single fibers. We found that IIX/IIB hybrids represent ∼25 and 50% of the fibers in the mouse tibialis anterior and brachioradialis, respectively. The relative proportion of the IIX and IIB isoforms in these fibers spans a continuum, from predominantly IIB-like hybrids to IIX-like hybrids. Quantitative assessment of mRNA levels using real-time PCR from single fibers indicated that IIB expression dominated over IIX expression in most fibers and that a general correlation existed between mRNA isoform levels and MHC protein content. However, the match between mRNA levels and protein content was not precise. Finally, we measured MHC isoform proportions in adjacent fiber segments and discovered that ∼30% of hybrids possessed significant differences in isoform content along their length. In some instances, the muscle fiber type as defined by MHC content changed completely along the length of a fiber. This pattern of asymmetrical MHC isoform content along the length of single fibers suggests that the multiple myonuclei of a muscle fiber may express distinct myofibrillar isoforms in an uncoordinated fashion.

scholarly journals Tyrosinase Small Interfering RNA Effectively Suppresses Tyrosinase Gene Expression In Vitro and In Vivo

2010 ◽  
Vol 2010 ◽  
pp. 1-6
Author(s):  
Jia Xiu-Hua ◽  
Lin Shao-Chun ◽  
Huang Bing ◽  
Zhu Xiang ◽  
Zhuang Jing ◽  
...  
Keyword(s):  
Small Interfering Rna ◽  
Initial Step ◽  
Tyrosinase Activity ◽  
Stable Gene ◽  
Mrna Levels ◽  
Melanin Content ◽  
Melanin Biosynthesis ◽  
Interfering Rna

Tyrosinase is a bifunctional enzyme which oxidizes the initial step of melanin biosynthesis, that is, conversion of tyrosine to dopa and subsequently dopa to dopaquinone. It is a glycosylated protein and a major regulator of melanogenesis. To date, many approaches have been tried to regulate tyrosinase activity and melanin content. To that end, we screened small interfering RNA sequences for sequence-inhibited tyrosinase expression in B16 cells and in C57BL/6 mice. We analyzed tyrosinase mRNA levels by quantitative real-time PCR and determined tyrosinase activity and melanin content at 24, 48, and 72 hours after transfection. Results showed that siNM_011661_001 was the most efficient small interfering RNA sequence in suppressing tyrosinase mRNA expression, and cells transfected with this sequence showed lower tyrosinase activity. Moreover, intravitreous injection of siNM_011661_001 in C57BL/6 mice induced an efficient and stable gene-specific inhibition of expression at the posttranscriptional level.

Length-tension relationship of mammalian diaphragm muscles

1983 ◽  
Vol 54 (6) ◽  
pp. 1681-1686 ◽  
Author(s):  
K. K. McCully ◽  
J. A. Faulkner
Keyword(s):  
Muscle Fiber ◽  
Relaxation Times ◽  
Isometric Tension ◽  
Diaphragm Muscle ◽  
Muscle Fiber Types ◽  
Fiber Types ◽  
Active Tension ◽  
Tension Curves ◽  
Relationship Of

We tested the hypothesis that the length-tension relationship of diaphragm muscle is different from that of other skeletal muscle. Isometric contractile properties of small bundles of diaphragm muscle from rats, cats, rhesus monkeys, dogs, and pigs were measured in vitro at 37 degrees C. For diaphragm muscles from all species, twitch contraction and relaxation times and histochemical myofibrillar ATPase indicated a mixture of fast and slow muscle fiber types. By use of tetanic stimulations of 400-ms duration, isometric tension was recorded from bundles of diaphragm muscle at lengths between 50 and 130% of the muscle fiber length at which active tension was maximal (Lo). At lengths below 60–70% of Lo, tetanic tension did not reach a plateau within 400 ms. With longer stimulation durations, active tension could be recorded between 30 and 40% of Lo. The length-tension curves for bundles of fibers from the diaphragm muscle were not different among species and were consistent with results reported for intact limb muscles.

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