The Multiple Faces of MNT and Its Role as a MYC Modulator

Body-Wide Inactivation of the Myc-Like Mlx Transcription Factor Network Accelerates Aging and Increases the Lifetime Cancer Incidence

The "Mlx" and "Myc" transcription factor networks cross-communicate and share many common gene targets. Myc's activity depends upon its heterodimerization with Max, whereas the Mlx Network requires that the Max-like factor Mlx associate with the Myc-like factors MondoA or ChREBP. The current work demonstrates that body-wide Mlx inactivation, like that of Myc, accelerates numerous aging-related phenotypes pertaining to body habitus and metabolism. The deregulation of numerous aging-related Myc target gene sets is also accelerated. Among other functions, these gene sets often regulate ribosomal and mitochondrial structure and function, genomic stability, and aging. Whereas "MycKO" mice have an extended lifespan because of a lower cancer incidence, "MlxKO" mice have normal lifespans and a higher cancer incidence. Like Myc, the expression of Mlx, MondoA, and ChREBP and their control over their target genes deteriorate with age in both mice and humans. Collectively, these findings underscore the importance of lifelong and balanced cross-talk between the two networks to maintain proper function and regulation of the many factors that can affect normal aging.

MNT inhibits lung adenocarcinoma ferroptosis and chemosensitivity by suppressing SAT1

Ferroptosis, a type of iron-dependent non-apoptotic cell death, plays a vital role in both tumor proliferation and resistance to chemotherapy. Here, our study demonstrates that MAX's Next Tango (MNT), by involving itself in the spermidine/spermine N1-acetyltransferase 1 (SAT1)-related ferroptosis pathway, promotes the proliferation of lung adenocarcinoma (LUAD) cells and diminishes their sensitivity to chemotherapy. Initially, an RNA-sequence screen of LUAD cells treated with ferroptosis inducers (FINs) reveals a significant increase in MNT expression, suggesting a potential link between MNT and ferroptosis. Overexpression of MNT in LUAD cells hinders changes associated with ferroptosis. Moreover, the upregulation of MNT promotes cell proliferation and suppresses chemotherapy sensitivity, while the knockdown of MNT has the opposite effect. Through the intersection of ChIP-Seq and ferroptosis-associated gene sets, and validation by qPCR and western blot, SAT1 is identified as a potential target of MNT. Subsequently, we demonstrate that MNT binds to the promoter sequence of SAT1 and suppresses its transcription by ChIP-qPCR and dual luciferase assays. Restoration of SAT1 levels antagonizes the efficacy of MNT to inhibit ferroptosis and chemosensitivity and promote cell growth in vitro as well as in vivo. In the clinical context, MNT expression is elevated in LUAD and is inversely connected with SAT1 expression. High MNT expression is also associated with poor patient survival. Our research reveals that MNT inhibits ferroptosis, and impairing chemotherapy effectiveness of LUAD.

Impact of Hypoxia-Induced miR-210 on Pancreatic Cancer

Pancreatic cancer (PC) poses significant clinical challenges, with late-stage diagnosis and limited therapeutic options contributing to its dismal prognosis. A hallmark feature of PC is the presence of a profoundly hypoxic tumour microenvironment, resulting from various factors such as fibrotic stroma, rapid tumour cell proliferation, and poor vascularization. Hypoxia plays a crucial role in promoting aggressive cancer behaviour, therapeutic resistance, and immunosuppression. Previous studies have explored the molecular mechanisms behind hypoxia-induced changes in PC, focusing on the role of hypoxia-inducible factors (HIFs). Among the myriad of molecules affected by hypoxia, microRNA-210 (miR-210) emerges as a central player. It is highly responsive to hypoxia and regulated by HIF-dependent and HIF-independent pathways. miR-210 influences critical cellular processes, including angiogenesis, metastasis, and apoptosis, all of which contribute to PC progression and resistance to treatment. Understanding these pathways provides insights into potential therapeutic targets. Furthermore, investigating the role of miR-210 and its regulation in hypoxia sheds light on the potential development of early diagnostic strategies, which are urgently needed to improve outcomes for PC patients. This review delves into the complexities of PC and introduces the roles of hypoxia and miR-210 in the progression of PC.

Genetic variants of TORC1 gene promoter and their association with carcass quality and body measurement traits in Qinchuan beef cattle

In the present study, sequencing of TORC1 prompter region explored three SNPs at loci g.80G>T, g.93A>T, and g.1253G>A. The SNP1 produced GG, GT and TT, SNP2 AA, AT and TT, and SNP3 produced GG, GA and AA genotypes. Allelic and genotypic frequencies analysis exhibited that SNP1 is within Hardy-Weinberg equilibrium (HWE). All three SNPs were found highly polymorphic as PIC value (0.25 < PIC < 0.50). At loci g.80G>T the cattle with genotype GG showed significantly (P <0.01) larger body length (BL), Wither height (WH), Hip height (HH), Rump length (RL), Hip width (HW), Chest depth (CD), and Chest circumference (CC). The genotype AA at g.93A>T showed significantly (P< 0.01 and 0.05) Larger body length (BL), Wither height (WH), Hip height, Rump length (RL), Hip width (HW), Chest depth (CD), and Chest circumference (CC). Interestingly, the carcass quality parameters such as Ultrasound loin area (ULA) and Intramuscular fat percentage (IF%) was highest in genotype GG at loci g.1253G>A. These findings conclude that genotype GG at loci g.80 G>T and AA at loci g.93A>T could be used as genetic markers for body measurement and genotype GG at loci g.1253G>A for carcass quality traits of TORC1 gene in Qinchuan beef cattle.

The Myc-Like Mlx Network Impacts Aging and Metabolism

The "Mlx" and "Myc" Networks share many common gene targets. Just as Myc's activity depends upon its heterodimerization with Max, the Mlx Network requires that the Max-like factor Mlx associate with the Myc-like factors MondoA or ChREBP. We show here that body-wide Mlx inactivation, like that of Myc, accelerates numerous aging-related phenotypes pertaining to body habitus and metabolism. The deregulation of numerous aging-related Myc target gene sets is also accelerated. Among other functions, these gene sets often regulate ribosomal and mitochondrial structure and function, genomic stability and aging. Whereas "MycKO" mice have an extended lifespan because of a lower cancer incidence, "MlxKO" mice have normal lifespans and a somewhat higher cancer incidence. Like Myc, Mlx, MondoA and ChREBP expression and that of their target genes, deteriorate with age in both mice and humans, underscoring the importance of life-long and balanced cross-talk between the two Networks to maintain normal aging.

MNT suppresses T cell apoptosis via BIM and is critical for T lymphomagenesis

The importance of c-MYC in regulating lymphopoiesis and promoting lymphomagenesis is well-established. Far less appreciated is the vital supporting role of MYC's relative MNT. Using Rag1Cre-mediated Mnt deletion in lymphoid progenitor cells, we show here that, during normal T cell development, MNT loss enhances apoptosis, at least in part by elevating expression of the pro-apoptotic BH3-only protein BIM. Moreover, using T lymphoma-prone VavP-MYC transgenic mice, we show that Mnt deletion reduces the pool of pre-malignant MYC-driven T lymphoid cells and abrogates thymic T lymphomagenesis. In addition, we establish that Mnt deletion prevents T lymphoma development in γ-irradiated mice, most likely by enhancing apoptosis of T lymphoid cells repopulating the depleted thymus. Taken together with our recent demonstration that MNT is vital for the survival of MYC-driven pre-malignant and malignant B lymphoid cells, these results suggest that MNT represents an important new drug target for both T and B lymphoid malignancies.

Regulation of Normal and Neoplastic Proliferation and Metabolism by the Extended Myc Network

The Myc Network, comprising a small assemblage of bHLH-ZIP transcription factors, regulates many hundreds to thousands of genes involved in proliferation, energy metabolism, translation and other activities. A structurally and functionally related set of factors known as the Mlx Network also supervises some of these same functions via the regulation of a more limited but overlapping transcriptional repertoire. Target gene co-regulation by these two Networks is the result of their sharing of three members that suppress target gene expression as well as by the ability of both Network's members to cross-bind one another's consensus DNA sites. The two Networks also differ in that the Mlx Network's control over transcription is positively regulated by several glycolytic pathway intermediates and other metabolites. These distinctive properties, functions and tissue expression patterns potentially allow for sensitive control of gene regulation in ways that are differentially responsive to environmental and metabolic cues while allowing for them to be both rapid and of limited duration. This review explores how such control might occur. It further discusses how the actual functional dependencies of the Myc and Mlx Networks rely upon cellular context and how they may differ between normal and neoplastic cells. Finally, consideration is given to how future studies may permit a more refined understanding of the functional interrelationships between the two Networks.

FTO Alleviates CdCl2-Induced Apoptosis and Oxidative Stress via the AKT/Nrf2 Pathway in Bovine Granulosa Cells

Cadmium (Cd) is a common environmental heavy metal contaminant of reproduction toxicity. Cd accumulation in animals leads to the damage of granulosa cells. However, its mechanism needs to be elucidated. This research found that treating granulosa cells with Cd resulted in reduced cell viability. The flow cytometry results showed that Cd increased the degree of apoptosis and level of superoxide anion (O₂^-) in granulosa cells. Further analysis showed that Cd treatment resulted in reduced expression levels of nuclear factor erythroid 2-related factor-2 (Nrf2), superoxide dismutase (SOD), catalase (CAT) and NAD(P)H: quinone oxidoreductase 1 (NQO1), and an increased expression level of malondialdehyde (MDA); the expression levels of Bcl-2 associated X (Bax) and caspase-3 increased, whereas that of B-cell lymphoma 2 (Bcl-2) decreased. Changes in m⁶A methylation-related enzymes were noted with Cd-induced damage to granulosa cells. The results of transcriptome and MeRIP sequencing revealed that the AKT pathway participated in Cd-induced damage in granulosa cells, and the MAX network transcriptional repressor (MNT) may be a potential target gene of fat mass and obesity-associated protein (FTO). FTO and YTH domain family member 2 (YTHDF2) regulated MNT expression through m⁶A modification. FTO overexpression alleviated Cd-induced apoptosis and oxidative stress through the activation of the AKT/Nrf2 pathway; this process could be reversed using siMNT. Overall, these findings associated m⁶A with Cd-induced damage to granulosa cells and provided insights into Cd-induced granulosa cell cytotoxicity from a new perspective centered on m⁶A modification.