The Binding of Platinum (II) Complexes to Rabbit Skeletal Muscle G-Actin Induces Conformation Changes

The binding of cis-diamminedichloroplatinum (DDCP) and cis-diaquodiammine platinum (DADP) to rabbit skeletal muscle G-actin and the consequent conformation changes were studied as the function of the Pt/actin molar ratio (R) and time by intrinsic and NPM labeled fluorescence, CD spectra as well as gelfiltration chromatography. The results indicated that the unhydrolyzed DDCP can react with G-actin in presence of Cl(-) ion. The reaction differs from that of its hydrolysis product DADP in a higher specificity and a lower capacity. Both of them induced exposure of the tryptophane residues and labeled Cys374 and the increase in alpha-helix content depending on R, but the conformation changes caused by DADP are more significant than DDCP at the same R. These are related to the binding of DADP to groups other than thiols. The rate constants of conformation change suggested that DADP quenched the intrinsic fluorescence more rapid. The temporal change in fluorescence of NPM labeled actin has a biphasic feature: in the first 16 minutes, the fluorescence was quenched, then it recovered slowly, indicating a multi-step reaction including high affinity platinum binding --> labeled Cys374 moving to hydrophilic environment --> low affinity platinum binding --> Cys374-related conformation compacting in sequence.     

Spectroscopic Comparison of Eu(III) Binding to Various Biosorbents

Biosorption of Eu(III) to various biogenic materials was investigated using luminescence spectroscopy involving excitation of non-degenerate ⁷F₀ → ⁵D₀ transition of bound metal ions. Materials included cultured anther cell fragments from Datura innoxia, pecan shells (Protandrous spp.), dried bean sprouts (vigna spp.), and dried tissues from the roots, stems, and leaves of mature tumbleweeds (Salsola spp.), non-viable algae cells of Chlorella vulgaris immobilized within a polysilicate matrix, sphagnum peat, dried peat, and a commercially available organic peat material. Analysis of resulting excitation spectra indicated only minimal variation in binding environments for the different tumbleweed tissues when respective spectra were visually compared. Observed red-shifts in excitation spectral envelopes suggest an increased stabilization of surface ligand-metal associations for all materials compared to D. innoixia. Application of principal component analysis to these spectra resulted in segregation of materials using a model accounting for 89.48% of the variance using three principal components. This analysis revealed similarities among the spectra from the roots and stems of the tumbleweeds along with that from the bean sprout sample. The model confirmed differences in metal binding to the D. innoxia materials. It also indicated significant differences in metal ion binding to the organic peat and Chlorella-based biosorbents.     

CircTCF4 Suppresses Proliferation and Differentiation of Goat Skeletal Muscle Satellite Cells Independent from AGO2 Binding

The proliferation and differentiation of mammalian skeletal muscle satellite cells (MuSCs) are highly complicated. Apart from the regulatory signaling cascade driven by the protein-coding genes, non-coding RNAs such as microRNAs (miRNA) and circular RNAs (circRNAs) play essential roles in this biological process. However, circRNA functions in MuSCs proliferation and differentiation remain largely to be elucidated. Here, we screened for an exonic circTCF4 based on our previous RNA-Seq data, specifically expressed during the development of the longest dorsal muscle in goats. Subsequently, the circular structure and whole sequence of circTCF4 were verified using Sanger sequencing. Besides, circTCF4 was spatiotemporally expressed in multiple tissues from goats but strikingly enriched in muscles. Furthermore, circTCF4 suppressed MuSCs proliferation and differentiation, independent of AGO2 binding. Finally, we conducted Poly(A) RNA-Seq using cells treated with small interfering RNA targeting circTCF4 and found that circTCF4 would affect multiple signaling pathways, including the insulin signaling pathway and AMPK signaling pathway related to muscle differentiation. Our results provide additional solid evidence for circRNA regulating skeletal muscle formation.     

Impact of Conjugated Linoleic Acid (CLA) on Skeletal Muscle Metabolism

Conjugated linoleic acid (CLA) has garnered special attention as a food bioactive compound that prevents and attenuates obesity. Although most studies on the effects of CLA on obesity have focused on the reduction of body fat, a number of studies have demonstrated that CLA also increases lean body mass and enhances physical performances. It has been suggested that these effects may be due in part to physiological changes in the skeletal muscle, such as changes in the muscle fiber type transformation, alteration of the intracellular signaling pathways in muscle metabolism, or energy metabolism. However, the mode of action for CLA in muscle metabolism is not completely understood. The purpose of this review is to summarize the current knowledge of the effects of CLA on skeletal muscle metabolism. Given that CLA not only reduces body fat, but also improves lean mass, there is great potential for the use of CLA to improve muscle metabolism, which would have a significant health impact.     

家兔肌钙蛋白的分离纯化

目的 分离提纯肌钙蛋白Ｉ（ＴｎＩ）以便制备心肌梗塞诊断试剂。方法 采用离子交换、分子筛、疏水 层析相结合的方法分离纯化兔骨骼肌肌钙蛋白Ｃ（ｓＴｎＣ）．制备ＴｎＧ－Ｓｅｐｈａｒｏｓｅ４Ｂ亲和层析柱。结果 所提纯的ｓＴ－ ｎＣ,经ＳＤＳ－ＰＡＧＥ分析已达到电泳纯,经ＵＶ－２５０扫描显示出特异性吸收曲线,证明其含有较多的苯丙氨酸,而不含 色氨酸,进一步证明其纯度。结论 为提纯ＴｎＩ创造了条件。     

Olive Leaf Polyphenols (OLPs) Stimulate GLUT4 Expression and Translocation in the Skeletal Muscle of Diabetic Rats

Skeletal muscles are high-insulin tissues responsible for disposing of glucose via the highly regulated process of facilitated glucose transporter 4 (GLUT4). Impaired insulin action in diabetes, as well as disorders of GLUT4 vesicle trafficking in the muscle, are involved in defects in insulin-stimulated GLUT4 translocation. Since the Rab GTPases are the main regulators of vesicular membrane transport in exo- and endo-cytosis, in the present work, we studied the effect of olive leaf polyphenols (OLPs) on Rab8A, Rab13, and Rab14 proteins of the rat soleus muscle in a model of streptozotocin (SZT)-induced diabetes (DM) in a dose-dependent manner. Glucose, cholesterol, and triglyceride levels were determined in the blood, morphological changes of the muscle tissue were captured by hematoxylin and eosin histological staining, and expression of GLUT4, Rab8A, Rab13, and Rab14 proteins were analyzed in the rat soleus muscle by the immunofluorescence staining and immunoblotting. OLPs significantly reduced blood glucose level in all treated groups. Furthermore, significantly reduced blood triglycerides were found in the groups with the lowest and highest OLPs treatment. The dynamics of activation of Rab8A, Rab13, and Rab14 was OLPs dose-dependent and more effective at higher OLP doses. Thus, these results indicate a beneficial role of phenolic compounds from the olive leaf in the regulation of glucose homeostasis in the skeletal muscle.     

A Plasma Proteomic Signature of Skeletal Muscle Mitochondrial Function

Although mitochondrial dysfunction has been implicated in aging, physical function decline, and several age-related diseases, an accessible and affordable measure of mitochondrial health is still lacking. In this study we identified the proteomic signature of muscular mitochondrial oxidative capacity in plasma. In 165 adults, we analyzed the association between concentrations of plasma proteins, measured using the SOMAscan assay, and skeletal muscle maximal oxidative phosphorylation capacity assessed as post-exercise phosphocreatine recovery time constant (τ_PCr) by phosphorous magnetic resonance spectroscopy. Out of 1301 proteins analyzed, we identified 87 proteins significantly associated with τ_PCr, adjusting for age, sex, and phosphocreatine depletion. Sixty proteins were positively correlated with better oxidative capacity, while 27 proteins were correlated with poorer capacity. Specific clusters of plasma proteins were enriched in the following pathways: homeostasis of energy metabolism, proteostasis, response to oxidative stress, and inflammation. The generalizability of these findings would benefit from replication in an independent cohort and in longitudinal analyses.     

A Computational Study of Calcium(II) and Copper(II) Ion Binding to the Hyaluronate Molecule

The hyaluronate molecule is a negatively charged polysaccharide that performs a plethora of physiological functions in many cell tissues depending on its conformation. In the present paper, molecular modeling at three levels of theory and two basis sets was used to gain a deeper insight in the complex molecular structure of calcium(II) and copper(II) hyaluronate. Simulation results were compared with the experimental data (EXAFS or X-ray). It was found that B3LYP does not properly reproduce the experimental data while the HF and M06 methods do. Simulation data confirm that the N-acetyl group of the N-acetylglucosamine residue does not participate in the coordination bonding to the calcium(II) or copper(II) ion, as evident from the experimental data.     

Elemental Composition of Skeletal Muscle Fibres Studied with Synchrotron Radiation X-ray Fluorescence (SR-XRF)

Diseases of the muscle tissue, particularly those disorders which result from the pathology of individual muscle cells, are often called myopathies. The diversity of the content of individual cells is of interest with regard to their role in both biochemical mechanisms and the structure of muscle tissue itself. These studies focus on the preliminary analysis of the differences that may occur between diseased tissues and tissues that have been recognised as a reference group. To do so, 13 samples of biopsied human muscle tissues were studied: 3 diagnosed as dystrophies, 6 as (non-dystrophic) myopathy and 4 regarded as references. From these sets of muscle biopsies, 135 completely measured muscle fibres were separated altogether, which were subjected to investigations using synchrotron radiation X-ray fluorescence (SR-XRF). Muscle fibres were analysed in terms of the composition of elements such as Br, Ca, Cl, Cr, Cu, Fe, K, Mn, P, S and Zn. The performed statistical tests indicate that all three groups (dystrophies—D; myopathies—M; references—R) show statistically significant differences in their elemental compositions, and the greatest impact, according to the multivariate discriminate analysis (MDA), comes from elements such as Ca, Cu, K, Cl and S.     

Angiotensin-(1-7) Prevents Lipopolysaccharide-Induced Autophagy via the Mas Receptor in Skeletal Muscle

Skeletal muscle atrophy, which occurs in lipopolysaccharide (LPS)-induced sepsis, causes a severe muscle function reduction. The increased autophagy contributes to sepsis-induced skeletal muscle atrophy in a model of LPS injection, increasing LC3II/LC3I ratio, autophagy flux, and autophagosomes. Angiotensin-(1-7) (Ang-(1-7)) has anti-atrophic effects via the Mas receptor in skeletal muscle. However, the impact of Ang-(1-7) on LPS-induced autophagy is unknown. In this study, we determined the effect of Ang-(1-7) on sepsis-induced muscle autophagy. C57BL6 wild-type (WT) mice and mice lacking the Mas receptor (KO Mas) were injected with LPS together with the systemic administration of Ang-(1-7) to determine autophagy in skeletal muscle. We also evaluated autophagy and p38 and c-Jun N-terminal kinase (JNK)activation. Our results show that Ang-(1-7) prevents LPS-induced autophagy in the diaphragm, tibialis anterior, and gastrocnemius of WT mice, which is demonstrated by a decrease in the LC3II/LC3I ratio and mRNA levels of lc3b and ctsl. This effect was lost in KO Mas mice, suggesting the role of the Mas receptor. The results in C2C12 cells show that Ang-(1-7) reduces several LPS-dependent effects, such as autophagy (LC3II/LC3I ratio, autophagic flux, and autophagosomes), activation of p38 and JNK, B-cell lymphoma-2 (BCL2) phosphorylation, and disassembly of the Beclin1/BCL2 complex. In conclusion, Ang-(1-7)/Mas receptor reduces LPS-induced autophagy in skeletal muscle. In vitro assays indicate that Ang-(1-7) prevents LPS-induced autophagy and modifies the MAPK signaling and the disassembly of a complex involved at the beginning of autophagy.     

新型罗丹明类荧光标记探针的研究(Ⅰ)--氨基标记产物的质子化互变异构

罗丹明B-N-琥珀酰亚胺酯可用于生命体系物质氨基标记的新型荧光探针。研究了标记产物在不同的pH介质中的紫外一可见及荧光光谱特性，结合质子化互变异构机理，对互变异构现象与光谱变化的相关性进行了考察，确认了仲酰胺在中性和碱性条件下形成无荧光性的螺环内酰胺结构。     

4-(α-吡啶甲酰基)-PMP的合成与谱学特性研究

合成了新吡唑啉酮类试剂1-苯基-3-甲基-4-(α-吡啶甲酰基)-吡唑啉-5-酮(简称4-(α-吡啶甲酰基)-PMP,下同)。在表征分子结构的同时,对其红外、紫外吸收光谱,核磁共振氢谱、碳谱,质谱等谱学特性和质谱裂解规律进行了分析与研究。     

Localization and Spectroscopic Analysis of the Cu(I) Binding Site in Wheat Metallothionein Ec-1

The early cysteine-labeled metallothionein (MT) from Triticum aestivum (common wheat), denoted E_c-1, features two structurally well-defined domains, γ and β_E, coordinating two and four Zn(II) ions, respectively. While the protein is currently assumed to function mainly in zinc homeostasis, a low amount of copper ions was also recently detected in a native E_c-1 sample. To evaluate the observed copper binding in more detail, the recombinant Zn₆E_c-1 form was exposed to different amounts of Cu(I) ions and the resulting species characterized with spectroscopic methods. Data reveal that the first Cu(I) equivalent coordinates exclusively to the N-terminal γ-domain of the protein and replaces one Zn(II) ion. To analyze the ability of the γ-domain for coordination of monovalent metal ions in more detail, the γ-E_c-1 peptide fragment was incubated with increasing amounts of Cu(I) and the process monitored with UV–VIS, circular dichroism, and luminescence spectroscopy. Closely similar spectra are observed regardless if the apo- or the metal ion-loaded and, hence, pre-folded forms, were used for the titration experiments with Cu(I). The results indicate that low amounts of Cu(I) ions displace the two metal ions subsequently and stoichiometrically, despite the different coordination geometry requirements of Cu(I) and Zn(II).     

A Computational Simulation Study of Benzamidine Derivatives Binding to Arginine-Specific Gingipain (HRgpA) from Periodontopathogen Porphyromonas gingivalis

We have shown that the binding free energy calculation from molecular dynamics can be adapted successfully to cysteine proteinases, such as arginine-specific gingipain (HRgpA) from Porphyromonas gingivalis. The binding free energy obtained is in good agreement with the available experimental data for eight benzamidine derivatives including urea and ether linker. The calculations showed that the electrostatic energies between HRgpA and inhibitors were important in determining the relative affinities of the inhibitors to the HRgpA, with an average binding free energy of about -5 kcal/mol. The average structures of the eight complexes suggest that benzamidine inhibitors interact with Asp387, His435, and Cys468 by hydrogen bonding and with Trp508 by hydrophilic interactions that are essential for the activities of benzamidine inhibitors. It can therefore be expected that the method provides a reliable tool for the investigation of new HRgpA inhibitors. This finding could significantly benefit the future design of HRgpA inhibitors.     

Spectroscopic Study of Neodymium(III) in Sodium Tellurite Glass

The local environment of Nd-O in a sodium tellurite glass was elucidated as a function of Nd₂O₃ concentration, from 0.1 to 2.5 mol%, using optical spectroscopy. The Judd-Ofelt (J-O) theory was used to determine the oscillator strength parameters (J-O parameters) of the glasses. According to the J-O parameters, a significant change in the local environment of Nd-O was suggested for the glass containing 1 mol% Nd₂O₃; the asymmetry of the Nd-O crystal field was shown to be at a maximum and the bond covalency at a minimum. The results were further supported by a significant shift of the structural hypersensitive band of the glass with 1 mol% Nd₂O₃, as compared with those of the other glasses.     

Photopyroelectric Spectroscopic Studies of ZnO-MnO(2)-Co(3)O(4)-V(2)O(5) Ceramics

Photopyroelectric (PPE) spectroscopy is a nondestructive tool that is used to study the optical properties of the ceramics (ZnO + 0.4MnO(2) + 0.4Co(3)O(4) + xV(2)O(5)), x = 0-1 mol%. Wavelength of incident light, modulated at 10 Hz, was in the range of 300-800 nm. PPE spectrum with reference to the doping level and sintering temperature is discussed. Optical energy band-gap (E(g)) was 2.11 eV for 0.3 mol% V(2)O(5) at a sintering temperature of 1025 °C as determined from the plot (ρhυ)(2)versushυ. With a further increase in V(2)O(5), the value of E(g) was found to be 2.59 eV. Steepness factor 'σ(A)' and 'σ(B)', which characterize the slope of exponential optical absorption, is discussed with reference to the variation of E(g). XRD, SEM and EDAX are also used for characterization of the ceramic. For this ceramic, the maximum relative density and grain size was observed to be 91.8% and 9.5 μm, respectively.     

Histological Methods to Assess Skeletal Muscle Degeneration and Regeneration in Duchenne Muscular Dystrophy

Duchenne muscular dystrophy (DMD) is a progressive disease caused by the loss of function of the protein dystrophin. This protein contributes to the stabilisation of striated cells during contraction, as it anchors the cytoskeleton with components of the extracellular matrix through the dystrophin-associated protein complex (DAPC). Moreover, absence of the functional protein affects the expression and function of proteins within the DAPC, leading to molecular events responsible for myofibre damage, muscle weakening, disability and, eventually, premature death. Presently, there is no cure for DMD, but different treatments help manage some of the symptoms. Advances in genetic and exon-skipping therapies are the most promising intervention, the safety and efficiency of which are tested in animal models. In addition to in vivo functional tests, ex vivo molecular evaluation aids assess to what extent the therapy has contributed to the regenerative process. In this regard, the later advances in microscopy and image acquisition systems and the current expansion of antibodies for immunohistological evaluation together with the development of different spectrum fluorescent dyes have made histology a crucial tool. Nevertheless, the complexity of the molecular events that take place in dystrophic muscles, together with the rise of a multitude of markers for each of the phases of the process, makes the histological assessment a challenging task. Therefore, here, we summarise and explain the rationale behind different histological techniques used in the literature to assess degeneration and regeneration in the field of dystrophinopathies, focusing especially on those related to DMD.     

体外循环对兔骨骼肌葡萄糖转运蛋白4和胰岛葡萄糖转运蛋白2的影响

目的观察体外循环(Cardiopulmonary bypass,CPB)对兔骨骼肌葡萄糖转运蛋白4(Glucose transporter 4,GLUT4)和胰岛葡萄糖转运蛋白2(GLUT2)的影响,探讨CPB中高血糖的可能机制。方法取健康成年新西兰大白兔24只,随机分为正常对照组(N组)和CPB组(C组),每组12只。N组不行CPB,C组行CPB。两组分别于麻醉后即刻(T1)、主动脉阻断即刻(T2)、主动脉开放5min(T3)、主动脉开放35min(T4)和主动脉开放75min(T5)采集动脉血液,氧化酶法检测血糖水平,放免法检测胰岛素水平;免疫组织化学法检测主动脉开放5min和75min时骨骼肌总GLUT4和细胞膜上GLUT4的转位表达及开放75min时胰岛细胞GLUT2的表达。结果与T1比较,两组T2～T5的血糖和胰岛素水平均显著升高(P<0.05);C组T2～T5的血糖和胰岛素水平较N组显著升高(P<0.05);主动脉开放5min和75min时,C组骨骼肌总GLUT4和细胞膜上GLUT4的转位表达均显著下调(P<0.05);主动脉开放75min时,胰岛细胞GLUT2的表达显著上调(P<0.05);C组主动脉开放75min比5min时,骨骼肌总GLUT4和细胞膜上GLUT4的转位表达均显著上调(P<0.05)。结论兔CPB中高血糖可能与骨骼肌GLUT4表达下调和转位障碍有关。胰岛细胞GLUT2表达上调可能使胰岛素分泌增加,但增加的胰岛素并不能完全代偿高血糖。     

The 2-hydroxy-3-(4-aryl-1-piperazinyl)propyl Phthalimide Derivatives as Prodrugs—Spectroscopic and Theoretical Binding Studies with Plasma Proteins

Many publications in databases deal with the interactions of new drugs with albumin. However, it is not only albumin that is responsible for binding pharmaceutical molecules to proteins in the human body. There are many more proteins in plasma that are important for the study of the ADME pathway. Therefore, in this study, we have shown the results of the interactions between the plasma proteins albumin, orosomucoid, and gamma globulins and non-toxic anti-inflammatory phthalimide analogs, which due to the promising obtained results, may be potential candidates in the group of analgesic and anti-inflammatory drugs. Using spectroscopic methods and molecular modeling, we showed that all four tested compounds form complexes with the analyzed proteins. The formation of a complex with proteins raises the pharmacological efficacy of the drug. Therefore, the obtained results could be a step in the study of the pharmacokinetics and pharmacodynamics of new potential pharmaceuticals.     

Postnatal Protein Intake as a Determinant of Skeletal Muscle Structure and Function in Mice—A Pilot Study

Sarcopenia is characterised by an age-related decrease in the number of muscle fibres and additional weakening of the remaining fibres, resulting in a reduction in muscle mass and function. Many studies associate poor maternal nutrition during gestation and/or lactation with altered skeletal muscle homeostasis in the offspring and the development of sarcopenia. The aim of this study was to determine whether the musculoskeletal physiology in offspring born to mouse dams fed a low-protein diet during pregnancy was altered and whether any physiological changes could be modulated by the nutritional protein content in early postnatal stages. Thy1-YFP female mice were fed ad libitum on either a normal (20%) or a low-protein (5%) diet. Newborn pups were cross-fostered to different lactating dams (maintained on a 20% or 5% diet) to generate three groups analysed at weaning (21 days): Normal-to-Normal (NN), Normal-to-Low (NL) and Low-to-Normal (LN). Further offspring were maintained ad libitum on the same diet as during lactation until 12 weeks of age, creating another three groups (NNN, NLL, LNN). Mice on a low protein diet postnatally (NL, NLL) exhibited a significant reduction in body and muscle weight persisting up to 12 weeks, unlike mice on a low protein diet only prenatally (LN, LNN). Muscle fibre size was reduced in mice from the NL but not LN group, showing recovery at 12 weeks of age. Muscle force was reduced in NLL mice, concomitant with changes in the NMJ site and changes in atrophy-related and myosin genes. In addition, μCT scans of mouse tibiae at 12 weeks of age revealed changes in bone mass and morphology, resulting in a higher bone mass in the NLL group than the control NNN group. Finally, changes in the expression of miR-133 in the muscle of NLL mice suggest a regulatory role for this microRNA in muscle development in response to postnatal diet changes. Overall, this data shows that a low maternal protein diet and early postnatal life low-protein intake in mice can impact skeletal muscle physiology and function in early life while postnatal low protein diet favours bone integrity in adulthood.