Ubiquitin-proteasome dependent regulation of Profilin2 (Pfn2) by a cellular inhibitor of apoptotic protein 1 (cIAP1)

Profilin 2 isoform expression is associated with lung metastasis of colorectal cancer according to a comprehensive gene expression study using a mouse model

Lung metastasis is the second most common type of metastasis in colorectal cancer. Specific treatments for lung metastasis have not been developed since the underlying mechanisms are poorly understood. The present study aimed to elucidate the molecular basis of lung metastasis in colorectal cancer. In a mouse model, cell lines that were highly metastatic to the lungs were established by injecting colorectal cancer cells through the tail vein and removing them from the lungs. Differential gene expression comparing the transfected cells with their parental cells was investigated using DNA microarrays. The results were functionally interpreted using gene enrichment analysis and validated using reverse transcription-quantitative PCR (RT-qPCR). The isoforms of the identified genes were examined by melting curve analysis. The present study established colorectal cancer cell lines that were highly metastatic to the lungs. DNA microarray experiments revealed that genes (N-cadherin, VE-cadherin, Six4, Akt and VCAM1) involved in motility, proliferation and adhesion were upregulated, and genes (tissue inhibitor of metalloproteinase-3 and PAX6) with tumor-suppressive functions were downregulated in metastatic cells. Profilin 2 (PFN2) expression was upregulated in multiple metastatic cell lines using RT-qPCR. Two PFN2 isoforms were overexpressed in metastatic cells. In vitro and in vivo models were established and genes associated with lung metastasis were identified to overcome the heterogeneity of the disease. Overall, aberrant PFN2 expression is unreported in lung metastasis in colorectal cancer. In the present study, two PFN2 isoforms with differential tissue distribution were upregulated in metastatic cells, suggesting that they promote lung metastasis in colorectal cancer.

Role of Actin-Binding Proteins in Skeletal Myogenesis

Maintenance of skeletal muscle quantity and quality is essential to ensure various vital functions of the body. Muscle homeostasis is regulated by multiple cytoskeletal proteins and myogenic transcriptional programs responding to endogenous and exogenous signals influencing cell structure and function. Since actin is an essential component in cytoskeleton dynamics, actin-binding proteins (ABPs) have been recognized as crucial players in skeletal muscle health and diseases. Hence, dysregulation of ABPs leads to muscle atrophy characterized by loss of mass, strength, quality, and capacity for regeneration. This comprehensive review summarizes the recent studies that have unveiled the role of ABPs in actin cytoskeletal dynamics, with a particular focus on skeletal myogenesis and diseases. This provides insight into the molecular mechanisms that regulate skeletal myogenesis via ABPs as well as research avenues to identify potential therapeutic targets. Moreover, this review explores the implications of non-coding RNAs (ncRNAs) targeting ABPs in skeletal myogenesis and disorders based on recent achievements in ncRNA research. The studies presented here will enhance our understanding of the functional significance of ABPs and mechanotransduction-derived myogenic regulatory mechanisms. Furthermore, revealing how ncRNAs regulate ABPs will allow diverse therapeutic approaches for skeletal muscle disorders to be developed.

Changes in microRNA Expression in the Cochlear Nucleus and Inferior Colliculus after Acute Noise-Induced Hearing Loss

Noise-induced hearing loss (NIHL) can lead to secondary changes that induce neural plasticity in the central auditory pathway. These changes include decreases in the number of synapses, the degeneration of auditory nerve fibers, and reorganization of the cochlear nucleus (CN) and inferior colliculus (IC) in the brain. This study investigated the role of microRNAs (miRNAs) in the neural plasticity of the central auditory pathway after acute NIHL. Male Sprague–Dawley rats were exposed to white band noise at 115 dB for 2 h, and the auditory brainstem response (ABR) and morphology of the organ of Corti were evaluated on days 1 and 3. Following noise exposure, the ABR threshold shift was significantly smaller in the day 3 group, while wave II amplitudes were significantly larger in the day 3 group compared to the day 1 group. The organ of Corti on the basal turn showed evidence of damage and the number of surviving outer hair cells was significantly lower in the basal and middle turn areas of the hearing loss groups relative to controls. Five and three candidate miRNAs for each CN and IC were selected based on microarray analysis and quantitative reverse transcription PCR (RT-qPCR). The data confirmed that even short-term acoustic stimulation can lead to changes in neuroplasticity. Further studies are needed to validate the role of these candidate miRNAs. Such miRNAs may be used in the early diagnosis and treatment of neural plasticity of the central auditory pathway after acute NIHL.

Extracellular Vesicles of Human Periodontal Ligament Stem Cells Contain MicroRNAs Associated to Proto-Oncogenes: Implications in Cytokinesis

The human Periodontal Ligament Stem Cells (hPDLSCs) exhibit self-renewal capacity and clonogenicity potential. The Extracellular Vesicles (EVs) secreted by hPDLSCs are particles containing lipids, proteins, mRNAs, and non-coding RNAs, among which microRNAs, that are important in intercellular communication. The purpose of this study was the analysis of the non-coding RNAs contained in the EVs derived from hPDLSCs using Next Generation Sequencing. Moreover, our data were enriched using bioinformatic tools. The analysis highlighted the presence of non-coding RNAs and five microRNAs: MIR24-2, MIR142, MIR335, MIR490, and MIR296. Our results show that these miRNAs target the genes classified in two terms of the Gene Ontology: "Ras protein signal transduction" and "Actin/microtubule cytoskeleton organization." Noteworthy, the in-deep analysis of our EVs highlights that the miRNAs could be implicated in the silencing of proto-oncogenes involved in 12 different types of tumors.

IAP-Mediated Protein Ubiquitination in Regulating Cell Signaling

Over the last decade, the E3-ubiquitine ligases from IAP (Inhibitor of Apoptosis) family have emerged as potent regulators of immune response. In immune cells, they control signaling pathways driving differentiation and inflammation in response to stimulation of tumor necrosis factor receptor (TNFR) family, pattern-recognition receptors (PRRs), and some cytokine receptors. They are able to control the activity, the cellular fate, or the stability of actors of signaling pathways, acting at different levels from components of receptor-associated multiprotein complexes to signaling effectors and transcription factors, as well as cytoskeleton regulators. Much less is known about ubiquitination substrates involved in non-immune signaling pathways. This review aimed to present IAP ubiquitination substrates and the role of IAP-mediated ubiquitination in regulating signaling pathways.

PFN2a Suppresses C2C12 Myogenic Development by Inhibiting Proliferation and Promoting Apoptosis via the p53 Pathway

Skeletal muscle plays a crucial role in physical activity and in regulating body energy and protein balance. Myoblast proliferation, differentiation, and apoptosis are indispensable processes for myoblast myogenesis. Profilin 2a (PFN2a) is a ubiquitous actin monomer-binding protein and promotes lung cancer growth and metastasis through suppressing the nuclear localization of histone deacetylase 1 (HDAC1). However, how PFN2a regulates myoblast myogenic development is still not clear. We constructed a C2C12 mouse myoblast cell line overexpressing PFN2a. The CRISPR/Cas9 system was used to study the function of PFN2a in C2C12 myogenic development. We find that PFN2a suppresses proliferation and promotes apoptosis and consequentially downregulates C2C12 myogenic development. The suppression of PFN2a also decreases the amount of HDAC1 in the nucleus and increases the protein level of p53 during C2C12 myogenic development. Therefore, we propose that PFN2a suppresses C2C12 myogenic development via the p53 pathway. Si-p53 (siRNA-p53) reverses the PFN2a inhibitory effect on C2C12 proliferation and the PFN2a promotion effect on C2C12 apoptosis, and then attenuates the suppression of PFN2a on myogenic differentiation. Our results expand understanding of PFN2a regulatory mechanisms in myogenic development and suggest potential therapeutic targets for muscle atrophy-related diseases.