Relative expression of type II MAGE genes during retinoic acid-induced neural differentiation of mouse embryonic carcinoma P19 cells: a comparative real-time PCR analysis

Emerging roles of the MAGE protein family in stress response pathways

The melanoma antigen (MAGE) proteins all contain a MAGE homology domain. MAGE genes are conserved in all eukaryotes and have expanded from a single gene in lower eukaryotes to ∼40 genes in humans and mice. Whereas some MAGEs are ubiquitously expressed in tissues, others are expressed in only germ cells with aberrant reactivation in multiple cancers. Much of the initial research on MAGEs focused on exploiting their antigenicity and restricted expression pattern to target them with cancer immunotherapy. Beyond their potential clinical application and role in tumorigenesis, recent studies have shown that MAGE proteins regulate diverse cellular and developmental pathways, implicating them in many diseases besides cancer, including lung, renal, and neurodevelopmental disorders. At the molecular level, many MAGEs bind to E3 RING ubiquitin ligases and, thus, regulate their substrate specificity, ligase activity, and subcellular localization. On a broader scale, the MAGE genes likely expanded in eutherian mammals to protect the germline from environmental stress and aid in stress adaptation, and this stress tolerance may explain why many cancers aberrantly express MAGEs Here, we present an updated, comprehensive review on the MAGE family that highlights general characteristics, emphasizes recent comparative studies in mice, and describes the diverse functions exerted by individual MAGEs.

All-trans-retinoid acid induces the differentiation of P19 cells into neurons involved in the PI3K/Akt/GSK3β signaling pathway

The pluripotent mouse embryonal carcinoma cell line P19 is widely used as a model for research on all-trans-retinoid acid (RA)-induced neuronal differentiation; however, the signaling pathways involved in this process remain unclear. This study aimed to reveal the molecular mechanism underlying the RA-induced neuronal differentiation of P19 cells. Real-time quantitative polymerase chain reaction and Western blot analysis were used to determine the expression of neuronal-specific markers, whereas flow cytometry was used to analyze cell cycle and cell apoptosis. The expression profiles of messenger RNAs (mRNAs) in RA-induced neuronal differentiation of P19 cells were analyzed using high-throughput sequencing, and the functions of differentially expressed mRNAs (DEMs) were determined by bioinformatics analysis. RA induced an increase in both class III β-tubulin (TUBB3) and neurofilament medium (NEFM) mRNA expression, indicating that RA successfully induces neuronal differentiation of P19 cells. Cell apoptosis was not affected; however, cell proliferation decreased. We found 4117 DEMs, which were enriched in the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt) signaling pathway, Wnt signaling pathway, and cell cycle. Particularly, a few DEMs could be identified in the PI3K/Akt signaling pathway networks, such as PI3K, Akt, glycogen synthase kinase-3β (GSK3β), cyclin-dependent kinase 4 (CDK4), P21, and Bax. RA significantly increased the protein expression of PI3K, Akt, phosphorylated Akt, GSK3β, phosphorylated GSK3β, CDK4, and P21, but it reduced Bax protein expression. The Akt inhibitor affected the increase of TUBB3 and NEFM mRNA expression in RA-induced P19 cells. The molecular mechanism underlying the RA-induced neuronal differentiation of P19 cells is potentially involved in the PI3K/Akt/GSK3β signaling pathway. The decreased cell proliferation ability of neuronally differentiated P19 cells could be associated with the expression of cell cycle proteins.

Molecular evolution of type II MAGE genes from ancestral MAGED2 gene and their phylogenetic resolution of basal mammalian clades

Type II melanoma-associated antigens (MAGE) are a subgroup of about a dozen proteins found in various locations in the genome and expressed in normal tissues, thus are not related to cancer as the type I MAGE genes. This gene family exists as a single copy in non-mammals and monotremata, but found as two copies in metatherians and occur as a diverse group in all eutherians. Our studies suggest MAGED2 as the ancestor of this subfamily and the most likely evolutionary history of eutherian type II MAGE genes is hereby proposed based on synteny conservation, phylogenetic relations, genome location, homology conservation, and the protein and gene structures. Type II genes can be divided into two: those with 13 exons (MAGED1, MAGED2, TRO, and MAGED4) and those with only one exon (MAGEE1, MAGEE2, MAGEF1, NSMCE3, MAGEH1, MAGEL2, and NDN) with different evolutionary patterns. Our results suggest a need to change the gene nomenclature to MAGE1 (the ancestral gene), currently designated as LOC103095671 and LOC100935086, in opossum and Tasmanian devil, respectively, and MAGE2 (the duplicated one), currently designated as LOC100617402 and NDNL2, respectively, to avoid confusion. We reconstructed the phylogenetic relationships among 23 mammalian species using the combined sequences of MAGED1, MAGED2, MAGEL2, and NDN, because of their high divergence, and found high levels of support, being able to resolve the phylogenetic relationships among Euarchontoglires, Laurasiatheria, Afrotheria, and Xenarthra, as an example that small, but phylogenetically informative sequences, can be very useful for resolving basal mammalian clades.

Identification of Novel MAGE-G1-Interacting Partners in Retinoic Acid-Induced P19 Neuronal Differentiation Using SILAC-Based Proteomics

MAGE-G1 is a protein plays role in the early process of neurogenesis. However, the fundamental roles MAGE-G1 played in neurogenesis have not yet been completely understood. Finding the partners MAGE-G1 interacting with will surely contribute to the function study of MAGE-G1. In this study, using Stable Isotope Labeling by Amino acids in Cell culture-immunoprecipitation quantitative proteomics, we screened the interacting proteins of MAGE-G1 during retinoic acid -induced neuronal differentiation of P19 cells and firstly found that FSCN1 and VIME were potential novel MAGE-G1-interacting proteins. Then, the interaction between overexpressed MAGE-G1 and FSCN1 or VIME was validated by GST-pull down assay in bacteria and by co-immunoprecipitation assay in COS7 cells. Endogenous co-immunoprecipitation assay further confirmed that MAGE-G1 interacted with FSCN1 or VIME in P19 cells after a 6-day retinoic acid-induced neuronal differentiation. Those results provide a functional linkage between MAGE-G1 and FSCN1 or VIME and may facilitate a better understanding of the fundamental aspects of MAGE-G1 during neurogenesis.

Pilot Study on MAGE-C2 as a Potential Biomarker for Triple-Negative Breast Cancer

Objective. In the current study, we measured the expression status of melanoma antigen gene c2 (MAGE-C2) in triple-negative breast cancer (TNBC) and analyzed its prognostic with the clinical pathological features of patients with TNBC. Methods. The expressions statuses of MAGE-C2 were detected in TNBC tissues and paracarcinoma tissues by immunohistochemistry, reverse transcription-polymerase chain reaction (RT-PCR), and western blotting. Then, we investigated the relationship of MAGE-C2 expression status and clinicopathological parameters of TNBC patients by the chi-squared test. Finally, we discussed the relations of MAGE-C2 expression state and prognosis of patients with TNBC by Kaplan-Meier method and Cox proportional hazards model. Results. High MAGE-C2 expression was found in 38.18% (42/110) of TNBC tissues. In adjacent tissues it was 9.09% (10/110). High MAGE-C2 expression in TNBC patients was closely associated with lymph node status, tumor node metastasis (TNM) stage, and lymphovascular invasion (P < 0.001). TNBC patients with high MAGE-C2 expression had significantly shorter survival time than low expression patients. We also found that age, lymph node status, TNM stage, lymphovascular invasion, and MAGE-C2 expression status were closely associated with overall survival of TNBC patients (P < 0.05). Conclusion. High MAGE-C2 expression may serve as an independent prognostic factor for TNBC patients.

Rnh1 promotes differentiation and myelination via RhoA in oligodendrocytes

Increases in Rattus norvegicus ribonuclease/angiogenin inhibitor 1 (Rnh1) are observed in rat primary neuron injury and/or the regeneration process and in differentiated oligodendrocytes. However, the roles of Rnh1 in the central nervous system are still largely unexplored. RhoA is an important signaling protein that has been implicated in oligodendrocyte differentiation and myelination. We demonstrate enhanced differentiation and myelination of oligodendrocytes mediated by Rnh1 in vitro. We further show that Rnh1 is expressed in oligodendrocyte precursors and oligodendrocytes. Importantly, Rnh1 strongly affects oligodendrocyte differentiation through RhoA-ROCK signaling. Moreover, changes in Rnh1 expression in oligodendrocytes regulates the expression and phosphorylation of Fyn, a regulator of RhoA activity. Finally, Rnh1 promotes myelination in vitro. These results show that Rnh1-mediated RhoA inactivation enhances the differentiation and myelination in oligodendrocytes. Overall, Rnh1 might contribute to oligodendrocyte differentiation and myelination processes in vitro.