Optical Cross-Sectional Muscle Area Determination of Drosophila Melanogaster Adult Indirect Flight Muscles

Multifaceted functions of RPS27a: An unconventional ribosomal protein

The ribosomal protein S27a (RPS27a) is cleaved from the fusion protein ubiquitin-RPS27a (Ub-RPS27a). Generally, Ub and RPS27a are coexpressed as a fusion protein but function independently after Ub is cleaved from RPS27a by a deubiquitinating enzyme. As an RP, RPS27a assembles into ribosomes, but it also functions independently of ribosomes. RPS27a is involved in the development and poor prognosis of various cancers, such as colorectal cancer, liver cancer, chronic myeloid leukemia, and renal carcinoma, and is associated with poor prognosis. Notably, the murine double minute 2/P53 axis is a major pathway through which RPS27a regulates cancer development. Moreover, RPS27a maintains sperm motility, regulates winged aphid indirect flight muscle degeneration, and facilitates plant growth. Additionally, RPS27a is a metalloprotein and mercury (Hg) biomarker. In the present review, we described the origin, structure, and biological functions of RPS27a.

Defined D-hexapeptides bind CUG repeats and rescue phenotypes of myotonic dystrophy myotubes in a Drosophila model of the disease

In Myotonic Dystrophy type 1 (DM1), a non-coding CTG repeats rare expansion disease; toxic double-stranded RNA hairpins sequester the RNA-binding proteins Muscleblind-like 1 and 2 (MBNL1 and 2) and trigger other DM1-related pathogenesis pathway defects. In this paper, we characterize four d-amino acid hexapeptides identified together with abp1, a peptide previously shown to stabilize CUG RNA in its single-stranded conformation. With the generalized sequence cpy(a/t)(q/w)e, these related peptides improved three MBNL-regulated exon inclusions in DM1-derived cells. Subsequent experiments showed that these compounds generally increased the relative expression of MBNL1 and its nuclear-cytoplasmic distribution, reduced hyperactivated autophagy, and increased the percentage of differentiated (Desmin-positive) cells in vitro. All peptides rescued atrophy of indirect flight muscles in a Drosophila model of the disease, and partially rescued muscle function according to climbing and flight tests. Investigation of their mechanism of action supports that all four compounds can bind to CUG repeats with slightly different association constant, but binding did not strongly influence the secondary structure of the toxic RNA in contrast to abp1. Finally, molecular modeling suggests a detailed view of the interactions of peptide-CUG RNA complexes useful in the chemical optimization of compounds.

Rabphilin involvement in filtration and molecular uptake in Drosophila nephrocytes suggests a similar role in human podocytes

Drosophila nephrocytes share functional, structural and molecular similarities with human podocytes. It is known that podocytes express the rabphilin 3A (RPH3A)-RAB3A complex, and its expression is altered in mouse and human proteinuric disease. Furthermore, we previously identified a polymorphism that suggested a role for RPH3A protein in the development of urinary albumin excretion. As endocytosis and vesicle trafficking are fundamental pathways for nephrocytes, the objective of this study was to assess the role of the RPH3A orthologue in Drosophila, Rabphilin (Rph), in the structure and function of nephrocytes. We confirmed that Rph is required for the correct function of the endocytic pathway in pericardial Drosophila nephrocytes. Knockdown of Rph reduced the expression of the cubilin and stick and stones genes, which encode proteins that are involved in protein uptake and filtration. We also found that reduced Rph expression resulted in a disappearance of the labyrinthine channel structure and a reduction in the number of endosomes, which ultimately leads to changes in the number and volume of nephrocytes. Finally, we demonstrated that the administration of retinoic acid to IR-Rph nephrocytes rescued some altered aspects, such as filtration and molecular uptake, as well as the maintenance of cell fate. According to our data, Rph is crucial for nephrocyte filtration and reabsorption, and it is required for the maintenance of the ultrastructure, integrity and differentiation of the nephrocyte.

20(S)-ginsenoside Rg3 promotes myoblast differentiation and protects against myotube atrophy via regulation of the Akt/mTOR/FoxO3 pathway

We previously found that 20(S)-ginsenoside Rg3 (S-Rg3) promotes myoblast differentiation via an unknown mechanism. Here we measured levels of myosin heavy chain (MHC) and myogenin, markers of myoblast differentiation, using Western blot analysis and immunofluorescence staining. Notably, S-Rg3 treatment of C2C12 myoblasts led to increased muscle differentiation and protection from muscle atrophy in a dexamethasone (DEX)-treated C2C12 myotube-based muscle atrophy model. This effect was likely caused by S-Rg3 treatment-induced promotion of Akt/mTOR phosphorylation and inhibition of FoxO3 nuclear transcription. Additionally, S-Rg3 treatment also led to increased fruit fly climbing distances (Drosophila melanogaster) and prevented muscle atrophy in aged fruit flies. Our study provides a mechanistic framework for understanding how S-Rg3 enhances myoblast differentiation and inhibits myotube atrophy through activation of the Akt/mTOR/FoxO3 signaling pathway, as demonstrated in vitro in C2C12 cells and in vivo in fruit flies.

Flight muscles degenerate by programmed cell death after migration in the wheat aphid, Sitobion avenae

OBJECTIVE

Previous studies showed that flight muscles degenerate after migration in some aphid species; however, the underlying molecular mechanism remains virtually unknown. In this study, using the wheat aphid, Sitobion avenae, we aim to investigate aphid flight muscle degeneration and the underlying molecular mechanism.

RESULTS

Sitobion avenae started to differentiate winged or wingless morphs at the second instar, the winged aphids were fully determined at the third instar, and their wings were fully developed at the fourth instar. After migration, the aphid flight muscles degenerated via programmed cell death, which is evidenced by a Terminal deoxynucleotidyl transferase dUTP-biotin nick-end labeling assay. Then, we identified a list of differentially expressed genes before and after tethered flights using differential-display reverse transcription-PCR. One of the differentially expressed genes, ubiquitin-ribosomal S27a, was confirmed using qPCR. Ubiquitin-ribosomal S27a is drastically up regulated following the aphids' migration and before the flight muscle degeneration. Our data suggested that aphid flight muscles degenerate after migration. During flight muscle degeneration, endogenous proteins may be degraded to reallocate energy for reproduction.