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DNA methylation is considered to play an important role in the development of diabetic retinopathy. Here, our goal was to investigate the precise role of methyl-CpG binding domain protein 2 (Mbd2) in the apoptosis of retinal ganglion cells (RGCs) in the early diabetic retina. Mbd2 was significantly upregulated after high glucose (HG) treatment and played a proapoptotic role in RGCs during HG-induced apoptosis. Combining ChIP and gene microarray datasets, the results showed that Mbd2 possessed potential binding sites for miR-345-5p, thereby elevating the expression levels of miR-345-5p via the enhancement of promoter demethylation. Activating transcription factor 1 (Atf1) played an anti-apoptotic role during the process of apoptosis in RGCs and acted as the target gene for miR-345-5p. Furthermore, the number of surviving RGCs in the diabetic retina was increased in Mbd2-knockout mice when compared with wild-type mice and the visual function became better accordingly. Collectively, our data demonstrated that the HG-induced overexpression of Mbd2 in the retina was partly responsible for the apoptosis of retinal neuronal cells through the miR-345-5p/Atf1 axis. Therefore, the targeting of Mbd2 might represent a novel therapeutic strategy for the treatment of neurodegeneration in the early diabetic retina.

Schizosaccharomyces pombe has been used as an excellent model for studying eukaryotic cell cycle regulation and stress responses. The bZIP transcription factors Atf1(ATF2 homolog) and Pcr1(CREB homolog) have been shown to be important for regulating the expression of genes related to both stress response and cell cycle. Pcr1 has in fact been implicated as a determining factor in the segregation of the cell cycle and stress response related functions of Atf1. Interestingly Atf1 and Pcr1 levels are known to vary during the cell cycle thus giving rise to the possibility that their relative levels can influence the periodic transcriptional program of the cell. Here we report our observations on the changes in transcriptome of S. pombe cells which have been genetically manipulated to create relative differences in the levels of Atf1 and Pcr1. These results highlight new information regarding the potential role of Atf1 and Pcr1 in orchestrating the integration of the transcriptional programs of cell cycle and stress response.

Malignant mesothelioma with EWSR1-ATF1 fusion is a rare malignancy described in young adults without asbestos exposure. To the best of our knowledge, outcomes to local and systemic therapies for this subtype of malignant mesothelioma have not been described. This case report describes the clinical course of a 19-year-old man diagnosed with malignant peritoneal mesothelioma with EWSR1-ATF1 fusion localized to the abdomen. His disease followed an aggressive course and resulted in limited survival (18 mo). There was treatment resistance to several lines of conventional local and systemic treatments for peritoneal mesothelioma and biologically targeted MET inhibition with crizotinib. More research is required in this rare subtype of peritoneal mesothelioma.

Diffuse intrinsic pontine glioma (DIPG) is a highly aggressive pediatric brain tumor with limited therapeutic options. Here, we investigated the potential of dimethyl alpha-ketoglutarate (DMKG) as an anti-proliferative agent against DIPG and unraveled its underlying molecular mechanisms. DMKG exhibited robust inhibition of DIPG cell proliferation, colony formation, and neurosphere growth. Transcriptomic analysis revealed substantial alterations in gene expression, with upregulated genes enriched in hypoxia-related pathways and downregulated genes associated with cell division and the mitotic cell cycle. Notably, DMKG induced G1/S phase cell cycle arrest and downregulated histone H3 lysine 27 acetylation (H3K27ac) without affecting H3 methylation levels. The inhibition of AKT and ERK signaling pathways by DMKG coincided with decreased expression of the CBP/p300 coactivator. Importantly, we identified the c-MYC-p300/ATF1-p300 axis as a key mediator of DMKG's effects, demonstrating reduced binding to target gene promoters and decreased H3K27ac levels. Depletion of c-MYC or ATF1 effectively inhibited DIPG cell growth. These findings highlight the potent anti-proliferative properties of DMKG, its impact on epigenetic modifications, and the involvement of the c-MYC-p300/ATF1-p300 axis in DIPG, shedding light on potential therapeutic strategies for this devastating disease., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Objectives: Salivary gland tumors are comprised of a diverse group of malignancies with widely varying prognoses. These cancers can be difficult to differentiate, especially in cases with limited potential for immunohistochemistry (IHC)-based characterization. Here, we sought to define the molecular profile of a rare salivary gland cancer called hyalinizing clear cell carcinoma (HCCC), and identify a molecular gene signature capable of distinguishing between HCCC and the histopathologically similar disease, mucoepidermoid carcinoma (MEC)., Materials and Methods: We performed the first integrated full characterization of five independent HCCC cases., Results: We discovered insulin-like growth factor alterations and aberrant IGF2 and/or IGF1R expression in HCCC tumors, suggesting a potential dependence on this pathway. Further, we identified a 354 gene signature that differentiated HCCC from MEC, and was significantly enriched for genes with an ATF1 binding motif in their promoters, supporting a transcriptional pathogenic mechanism of the characteristic EWSR1-ATF1 fusion found in these tumors. Of the differentially expressed genes, IGF1R, SGK1 and SGK3 were found to be elevated in the HCCCs relative to MECs. Finally, analysis of immune checkpoints and subsequent IHC demonstrated that CXCR4 protein was elevated in several of the HCCC cases., Conclusion: Collectively, our data identify an ATF1-motif enriched gene signature that may have clinical utility for molecular differentiation of HCCCs from other salivary gland tumors and discover potential actionable alterations that may benefit the clinical care of recurrent HCCC patients., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

Transcription factors are often the downstream effectors of signaling cascades. In fission yeast, the transcription factor Atf1 is phosphorylated by the MAP kinase Sty1 under several environmental stressors to promote transcription initiation of stress genes. However, Sty1 and Atf1 have also been involved in other cellular processes such as homologous recombination at hotspots, ste11 gene expression during mating and meiosis, or regulation of fbp1 gene transcription under glucose starvation conditions. Using different phospho-mutants of Atf1, we have investigated the role of Atf1 phosphorylation by Sty1 in those biological processes. An Atf1 mutant lacking the canonical MAP kinase phosphorylation sites cannot activate fbp1 transcription when glucose is depleted, but it is still able to induce recombination at ade6.M26 and to induce ste11 after nitrogen depletion; in these last cases, Sty1 is still required, suggesting that additional non-canonical sites are activating the transcription factor. In all cases, an Atf1 phosphomimetic mutant bypasses the requirement of the Sty1 kinase in these diverse biological processes, highlighting the essential role of the DNA binding factor Atf1 on chromatin remodeling and cell adaptation to nutritional changes. We propose that post-translational modifications of Atf1 by Sty1, either at canonical or non-canonical sites, are sufficient to activate some of the functions of Atf1, those involving chromatin remodeling and transcription initiation. However, in the case of fbp1 where Atf1 acts synergistically with other transcription factors, elimination of the canonical sites is sufficient to hamper some of the interactions required in this complex scenario and to impair transcription initiation., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Cyclic AMP-response element-binding protein (CREB) plays key transcriptional roles in cell metabolism, proliferation, and survival. Ser133 phosphorylation by protein kinase A (PKA) is a well-characterized CREB activation mechanism. Homeodomain-interacting protein kinase (HIPK) 2, a nuclear serine/threonine kinase, activates CREB through Ser271 phosphorylation; however, the regulatory mechanism remains uncharacterized. Transfection of CREB in HEK293 cells together with the kinase demonstrated that HIPK2 phosphorylated CREB at Ser271 but not Ser133; likewise, PKA phosphorylated CREB at Ser133 but not Ser271, suggesting two distinct CREB regulatory mechanisms by HIPK2 and PKA. In vitro kinase assay revealed that HIPK2, and HIPK1 and HIPK3, directly phosphorylated CREB. Cells exposed to 10μM sodium arsenite increased the stability of HIPK1 and HIPK2 proteins, leading to CREB activation via Ser271 phosphorylation. Phospho-Ser271 CREB showed facilitated interaction with the TFIID subunit coactivator TAF4 assessed by immunoprecipitation. Furthermore, a focused gene array between cells transfected with CREB alone and CREB plus HIPK2 over empty vector-transfected control displayed 14- and 32-fold upregulation of cyclin A1, respectively, while no upregulation was displayed by HIPK2 alone. These results suggest that the HIPK2-phospho-Ser271 CREB axis is a new arsenic-responsive CREB activation mechanism in parallel with the PKA-phospho-Ser133 CREB axis., (Copyright © 2016 Elsevier Ltd. All rights reserved.)