Gene and protein expressions of vimentin and desmin during embryonic development of the mylohyoid muscle

Development and Regeneration of Muscle, Tendon, and Myotendinous Junctions in Striated Skeletal Muscle

Owing to a rapid increase in aging population in recent years, the deterioration of motor function in older adults has become an important social problem, and several studies have aimed to investigate the mechanisms underlying muscle function decline. Furthermore, structural maintenance of the muscle–tendon–bone complexes in the muscle attachment sites is important for motor function, particularly for joints; however, the development and regeneration of these complexes have not been studied thoroughly and require further elucidation. Recent studies have provided insights into the roles of mesenchymal progenitors in the development and regeneration of muscles and myotendinous junctions. In particular, studies on muscles and myotendinous junctions have—through the use of the recently developed scRNA-seq—reported the presence of syncytia, thereby suggesting that fibroblasts may be transformed into myoblasts in a BMP-dependent manner. In addition, the high mobility group box 1—a DNA-binding protein found in nuclei—is reportedly involved in muscle regeneration. Furthermore, studies have identified several factors required for the formation of locomotor apparatuses, e.g., tenomodulin (Tnmd) and mohawk (Mkx), which are essential for tendon maturation.

Cardiomyocyte-like cell differentiation by FGF-2 transfection and induction of rat bone marrow mesenchymal stem cells

OBJECTIVE(S)

To investigate and test the hypotheses that FGF-2 enhanced myocardial differentiation with rat bone marrow mesenchymal stem cells (BMSCs).

MATERIALS AND METHODS

Lentiviral vectors carrying the FGF-2 gene were transfected into rat BMSCs firstly. According to the different inducing agents, they were divided into the following four groups: group A (BMSCs blank control group), group B (FGF-2 induction group), group C (Lenti-FGF-2-GFP lentivirus transfection group), and the group D (Lenti-control-GFP lentiviral transfer). Then several kinds of experimental methods such as real-time PCR, immunocytochemical staining, immunofluorescence staining, Western blot, and transmission electron microscopy were used to elucidate the effects by which FGF-2 adjusts myocardial differentiation in rat BMSCs.

RESULTS

The results of real-time PCR showed that GATA-4 and Nkx2.5 were expressed in all groups of cells. Compared with the experimental control group, the expression of GATA-4 and Nkx2.5 genes was the strongest after induction of 2 weeks in each induction group, and gradually decreased after induction of 4 weeks. Among them, the relative expression levels of GATA-4 and Nkx2.5 genes in Lenti-FGF-2-GFP were highest at all time points. The expressions of cTnI, cTnT, Cx43, and Desmin were detected by immunocytochemical staining and immunofluorescence staining. After 4 weeks of induction, cTnI, cTnT, Cx43, and Desmin were positively expressed in the cytoplasm of cells. Statistical analysis showed that the integrated optical density (IOD) values of the markers in the Lenti-FGF-2-GFP were the strongest. Cx43 and cTnI were weakly positive or negative in the experimental control group. There was a significant difference in the positive expression of each marker in each induction group and the experimental control group. Western blot analysis showed that Tromyosin (Tm) and Desmin were expressed in the blank group, FGF-2 drug-induced group, Lenti-FGF-2-GFP, and empty virus control transfection group after 4 weeks of induction, among which FGF-2 lentivirus transfected. The expression levels of Tm and Desmin were the highest in the staining induction group. Statistical analysis showed that the positive expressions of Tm and Desmin in each experimental group were statistically significant. Transmission electron microscopy showed that the nucleus of the cells transfected and induced by FGF-2 was located at the center of the cells. Myofilaments, rough endoplasmic reticulum, and mitochondria, and ribosomes were seen in the cytoplasm.

CONCLUSION

These results indicate that FGF-2 can transfect and induce differentiation of BMSCs into cardiomyocyte-like cells. Lentivirus-mediated FGF-2 transfection induces the differentiation of bone marrow mesenchymal stem cells into cardiomyocyte-like cells better than FGF-2 direct induction.

Morphological association between the muscles and bones in the craniofacial region

The strains of inbred laboratory mice are isogenic and homogeneous for over 98.6% of their genomes. However, geometric morphometric studies have demonstrated clear differences among the skull shapes of various mice strains. The question now arises: why are skull shapes different among the mice strains? Epigenetic processes, such as morphological interaction between the muscles and bones, may cause differences in the skull shapes among various mice strains. To test these predictions, the objective of this study is to examine the morphological association between a specific part of the skull and its adjacent muscle. We examined C57BL6J, BALB/cA, and ICR mice on embryonic days (E) 12.5 and 16.5 as well as on postnatal days (P) 0, 10, and 90. As a result, we found morphological differences between C57BL6J and BALB/cA mice with respect to the inferior spine of the hypophyseal cartilage or basisphenoid (SP) and the tensor veli palatini muscle (TVP) during the prenatal and postnatal periods. There was a morphological correlation between the SP and the TVP in the C57BL6J, BALB/cA, and ICR mice during E15 and P0. However, there were not correlation between the TVP and the SP during P10. After discectomy, bone deformation was associated with a change in the shape of the adjacent muscle. Therefore, epigenetic modifications linked to the interaction between the muscles and bones might occur easily during the prenatal period, and inflammation seems to allow epigenetic modifications between the two to occur.

Proteomics study reveals that the dysregulation of focal adhesion and ribosome contribute to early pregnancy loss

Purpose

Early pregnancy loss (EPL) affects 50–70% pregnant women in first trimester. The precise molecular mechanisms underlying EPL are far from being fully understood. Therefore, we aim to identify the molecular signaling pathways relating to EPL.

Experimental design

We performed proteomics and bioinformatics analysis of the placental villi in women who have undergone EPL and in normal pregnant women. The proteomics data were validated by Western blot analysis.

Results

We identified a total of 5952 proteins in placental villi, of which 588 proteins were differentially expressed in the EPL women. Bioinformatics analysis revealed that these differentially expressed proteins participated in a variety of signaling pathways, including the focal adhesion pathway and ribosome pathway. Moreover, results of the Western blot confirmed that Desmin, Lamin A/C, MMP‐9, and histone H4 were upregulated in EPL and the Lamin C/ Lamin A ratio decreased obviously in EPL. These proteins could be associated with the pathophysiology of EPL. The data have been deposited to the ProteomeXchange with identifier PXD002391.

Conclusion and clinical relevance

Our study demonstrated that the focal adhesion pathway and ribosome pathway are involved in EPL, and these findings might contribute to unveil the pathophysiology of EPL.