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.

Keywords: ATF1; Case report; EWSR1; Peritoneal mesothelioma.

Isoamyl acetate is an important flavor compound in sake. However, production of isoamyl acetate by Saccharomyces cerevisiae is significantly reduced during sake brewing with rice that has a high polishing ratio, because unsaturated fatty acids derived from the outer layer of rice repress the expression of ATF1, which encodes an alcohol acetyl transferase. Yeast mutants capable of relieving this repression would allow the brewing of rice with high polishing ratios, improving the diversity of taste and flavor of sake. Atf1p is also believed to contribute to biological membrane homeostasis. We isolated four yeast mutants (hia1, hia2, hia4, and hia6) that have high isoamyl acetate productivity and are resistant to aureobasidin A, an inhibitor of sphingolipid biosynthesis. The isoamyl acetate content of sake brewed with the hia1 mutant was 2.6 times higher than that of the parental strain. ATF1 was expressed constitutively in the hia1 mutant during brewing and remained derepressed upon the addition of unsaturated fatty acids. Whole-genome sequence analysis of the hia mutants revealed a homozygous nonsense mutation (Ser706*) in MGA2 in all four mutants. Mga2p, an endoplasmic reticulum (ER) membrane protein, regulates ATF1 transcription. The expression of ATF1 was elevated in BY4743 Δmga2 cells complemented with MGA2 (Ser706*), and this was not completely inhibited by the addition of unsaturated fatty acids. These results indicate that a nonsense mutation in MGA2 induces high levels of isoamyl acetate production in S. cerevisiae. This finding has applications for brewing sake with high levels of isoamyl acetate.

Colon cancer is the most aggressive tumor in both men and women globally. As many the chemotherapeutic regimens have adverse side effects and contribute to the resistance and recurrence, therefore, finding novel therapeutic targets and developing effective agents are urgent. Based on the TCGA and GTEx database analysis, RSK1 and MSK2 were found abnormal expressed in colon cancer. RSK1 and MSK2 were overexpressed in colon cancer tissues confirmed by western blot and IHC. After knocking down RSK1 or MSK2, cell proliferation and anchorage-independent cell growth were markedly inhibited. Using a computer docking model, we identified a novel dual-target inhibitor, APIO-EE-07, that could block both RSK1 and MSK2 kinase activity in a dose-dependent manner. APIO-EE-07 inhibited cell growth and induced apoptosis and also increased expression of Bax as well as cleaved caspase-3 and -PARP in colon cancer cells by downregulating RSK1 and MSK2 downstream targets, including CREB and ATF1. Furthermore, APIO-EE-07 decreased tumor volume and weight in human patient-derived xenografts tumors implanted in SCID mice. In summary, our results demonstrate that RSK1 and MSK2 are the potential targets for the treatment of colon cancer. APIO-EE-07, a novel dual-target inhibitor of RSK1 and MSK2, can suppress the growth of colon cancer by attenuating RSK1 and MSK2 signaling.

Myoepithelial tumors of soft tissue are rare mesenchymal neoplasms that overlap with their salivary gland and skin counterparts at both the histopathologic and molecular levels. EWSR1 gene rearrangements with various fusion partners represent a common genetic event in myoepithelial tumors of soft tissue, whether benign or malignant, and may prove useful as a diagnostic tool in difficult cases. However, the number of diagnostic entities with EWSR1 gene rearrangements has grown considerably in recent years, and there is significant morphologic and immunophenotypic overlap amongst this group, underscoring the importance of fusion testing to detect fusion partners that are characteristic of discrete diagnostic entities. Herein, we report a malignant myoepithelial tumor of soft tissue/myoepithelial carcinoma with an undifferentiated round cell morphology arising in a pediatric patient with a EWSR1-ATF1 gene fusion.

Keywords: EWSR1; EWSR1-ATF1; fusion; myoepithelial carcinoma; round cell; undifferentiated.

Upon heat shock, the fission yeast Hsp40 chaperone Mas5 drives temperature-sensitive proteins toward protein aggregate centers (PACs) to avoid their degradation until lower temperatures favor their refolding. We show here that cells lacking Mas5 are resistant to oxidative stress. Components of the general stress pathways, the MAP kinase Sty1 and the transcription factor Atf1, are suppressors of this phenotype. Strain Δmas5 expresses higher levels of Sty1- and Atf1-dependent stress genes than wild-type cells. Pyp1, the main tyrosine phosphatase maintaining Sty1 inactive in the absence of stress, is a temperature-sensitive protein that aggregates upon temperature up-shifts in a Mas5-dependent manner. In strain Δmas5, Pyp1 is sent to proteasomal degradation even in the absence of stress. We propose that Pyp1 is a thermo-sensitive phosphatase, which during heat stress coalescences into PACs in a Mas5-dependent manner, to promote full activation of the anti-stress Sty1-Atf1 cascade.

Keywords: Biological Sciences; Cell Biology; Molecular Biology.

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.

Keywords: ATF1; CXCR4; EWSR1; HCCC; IGF2.

The gastro-intestinal neuroectodermal tumor (GNET) is a rare sarcoma of the digestive tract, which was recently recognised. The knowledge of the morphological, immunohistochemical and molecular diagnostic criteria is necessary to not mistake it for the metastasis of a melanoma or for another sarcoma of the digestive tract as the gastro-intestinal clear cells sarcoma or the malignant peripheral nervous system tumor (MPNST). We report the case of a 41-year-old patient with a GNET of the small intestine with hepatic metastasis. The histological examination showed a diffuse proliferation of epithelioid cells, which only express PS100. The presence EWSR1-ATF1 gene fusions with any melanocytic differentiation leads to the diagnosis of GNET.

Morphological, ultrastructural and immunohistochemical characteristics of clear cell sarcoma (CCS) of the soft tissue frequently overlap with those of malignant melanoma. Thus, the differential diagnosis between the two lesions represents an important diagnostic dilemma. However, a number of genetic factors can be used to differentiate the two tumors; in particular, the t(12;22)(q13;q12) chromosomal translocation is typical of CCS, resulting in fusion of the EWSR1 gene on chromosome 22q12 and the ATF1 gene on chromosome 12q13. The detection of this molecular alteration has proved useful in the differential diagnosis of the two lesions. The present study reports the case of a 71-year-old male patient with a suspicious lymph node mass. Immunohistochemical analysis of the lesion indicated a diagnosis of metastatic melanoma, however, cytogenetic analysis using fluorescence in situ hybridization was additionally performed to investigate the chromosomal rearrangements of the 22q12 region and completely exclude the possibility of CCS. The current case did not demonstrate the presence of the translocation, supporting the diagnosis of melanoma. However, a clear orange amplification signal was observed relative to an ~500-kb region adjacent to the EWSR1 gene in the centromeric direction of chromosome 22q12. To the best of our knowledge, this is the first description of a 22q12 chromosomal alteration in melanoma. Furthermore, despite the presence of numerous genes in this region, their amplification has not previously been associated with the pathogenesis of melanoma.

Clear cell sarcoma (CCS) of the gastrointestinal tract presents a diagnostic challenge to the pathologist due to its morphological and immunohistochemical similarity to melanoma. It usually metastasizes to regional lymph nodes, liver, and lungs. Herein, we report the first known metastasis of a gastrointestinal CCS to the central nervous system. Cytogenetic testing showed the t(12,22) translocation corresponding to the presence of the EWS/ATF1 hybrid consistent with CCS. The literature that compares melanoma to CCS is reviewed in the context of this rare presentation to differentiate between the two diseases. .

The authors present a unique case of small cell variant of clear cell sarcoma of soft parts in a 42-year old woman. The tumor originally arose in the right flank of the soft tissues and ultimately developed both a local recurrence and multiple distant skin metastases two years and ten months thereafter. Nonspecific morphology of small blue round cell tumor was preserved at all microscopically verified sites and initially led to the spectrum of erroneous diagnoses such as an extraskeletal myxoid chondrosarcoma, Ewing sarcoma as well as malignant melanoma. The distinctive features of clear cell sarcoma such as fascicular nested growth pattern, spindling, clear cell change and/or eosinophilic cytoplasm were not disclosed even by extensive sampling. Immunohistochemically, the tumor expressed only S100protein and HMB45; all other markers (CD99, FLI1, cytokeratins, EMA) were completely negative. The molecular analysis carried out in one of the cutaneous metastases revealed translocation t(12;22) (EWSR1-ATF1) and ultimately led to the correct diagnosis of unusual Ewing-like clear cell sarcoma. Discussed is the implementation of molecular tests in routine diagnostics considering the existence of both histologically and biologically different tumors with an identical pathogenic molecular background.

Pathological diagnosis of dermal melanocytic tumors is often problematic owing to histological resemblance. Recently, cutaneous melanocytoma with CRTC1-TRIM11 (CMCT) was added to this category. However, only six cases have been reported so far. We herein present a case of a 77-year-old Japanese man with CMCT. The patient presented a nodule in the right thigh and underwent surgical resection. Histological examination indicated a well-demarcated 6 × 5 mm-sized tumor nodule in the dermis and subcutis. The tumor was amelanotic, consisting of uniform nests and fascicles of spindled, or epithelioid cells. The melanocytic nature was evident by immunohistochemistry. The CRTC1-TRIM11 fusion was detected by TRIM11 immunostaining, chromogenic in situ hybridization, and RT-PCR/direct sequencing. He has been free from the tumor for 1 year after additional resection. The main differential diagnosis of CMCT includes primary and metastatic dermal malignant melanomas (MM) and dermal/subcutaneous clear cell sarcoma (CCS). Additionally, histological overlap with paraganglioma-like dermal melanocytic tumor was considered. Although some investigators argue that CMCT is a variant of CCS, we think it should be separated from CCS, and subcutaneous/dermal CCS should be confined to tumors with EWSR1-ATF1/ CREB1 fusion. However, longer follow-up and more case studies are needed for revealing the true prognosis of CMCT.

Angiomatoid fibrous histiocytoma (AFH) is a soft tissue tumor of intermediate biologic potential and uncertain differentiation that most frequently occurs in the superficial extremities of children and young adults. It is histologically typified by nodules of ovoid to spindle cells with pseudoangiomatoid spaces and a surrounding dense lymphoplasmacytic infiltrate, desmin expression in about 50%, and association with EWSR1-CREB1, EWSR1-ATF1 or FUS-ATF1 gene fusions. The diagnosis still poses a challenge because AFH may not display all classic features, can show a variety of unusual histologic findings and lacks a specific immunoprofile. We describe a case of 'pure' spindle cell AFH arising in the forearm musculature of a 19 year-old female, which harbored EWSR1-CREB1 fusion transcripts by reverse transcription-polymerase chain reaction. The neoplasm was composed entirely of highly cellular fascicles of spindled cells architecturally resembling spindle cell sarcoma, and lacked obvious pseudoangiomatoid spaces or a lymphoid cuff. This purely spindle cell variant adds to the significant morphologic spectrum of AFH, and emphasizes that even when occuring at a typical site, AFH may be difficult to recognize when showing non-classical morphology. This is of clinical relevance, as AFH with this morphology could be potentially misdiagnosed as a high-grade sarcoma, with the patient subject to more radical therapeutic approaches.

Background: Cervical cancer (CC) is a common gynecological malignancy with a high risk of recurrence and death. Circular RNAs play a crucial role in the occurrence and development of tumors. This study aimed to investigate the function and mechanism of circ_0000745 in CC. Methods: The levels of circ_0000745, miR-409-3p, and activating transcription factor 1 (ATF1) were determined by quantitative real-time polymerase chain reaction or western blot assay. Cell proliferation was assessed by colony formation assay. Cell migration and invasion were evaluated by transwell assay. Glycolysis was analyzed by measuring extracellular acidification rate, glucose uptake, and lactate production. Also, the protein levels of glucose transporter 1 and lactate dehydrogenase A were detected using western blot. The relationship among circ_0000745, miR-409-3p, and ATF1 were confirmed by dual-luciferase reporter assay. Moreover, xenograft assay was performed to analyze tumor growth in vivo. Results: Circ_0000745 and ATF1 were upregulated, whereas miR-409-3p was downregulated in CC tissues and cells. Knockdown of circ_0000745 repressed proliferation, migration, invasion, and glycolysis of CC cells. Circ_0000745 regulated CC progression by targeting miR-409-3p. Circ_0000745 modulated ATF1 expression through sponging miR-409-3p. MiR-409-3p hindered CC progression by targeting ATF1. Furthermore, depletion of circ_0000745 impeded tumor growth in vivo. Conclusion: Circ_0000745 promoted the progression of CC through modulating miR-409-3p/ATF1 axis, indicating a promising biomarker for CC therapy.

Keywords: ATF1; cervical cancer; circ_0000745; miR-409-3p; progression.

Glabridin, an isoflavone isolated from licorice, owns a variety of pharmacological effects. Several reports have demonstrated that glabridin could regulate multiple cellular signaling pathways to inhibit the progression of cancer. However, the target proteins have not been elucidated yet. We used shape screening and induced fit docking to screen the protein data bank against glabridin. Braf and MEK1/2, important intermediate molecules of the braf/MEK cascade, were identified as the potential targets of glabridin. The experimental data showed that glabridin could inhibit the phosphorylation of MEK1/2 and the phosphorylation levels of downstream molecules including ERK1/2 and transcription factors ATF1 and CREB, but had no effect on the phosphorylation of braf. In particular, the in vitro pull-down assay indicated that glabridin selectively bound to braf and MEK1/2. What is more, exposure to glabridin significantly suppressed the proliferation of hepatocellular carcinoma HepG2 cell line. In addition, glabridin might arrest cell cycle in G1 through downregulation of cyclinD3, CDK2, and CDK4. In conclusion, glabridin is a potential multi-molecule-targeting inhibitor in the field of clinical prevention or treatment of cancer.

Clear cell sarcoma (CCS) is an aggressive mesenchymal malignancy characterized by the unique chimeric EWS-ATF1 fusion gene. Patient-derived cancer models are essential tools for the understanding of tumorigenesis and the development of anti-cancer drugs; however, only a limited number of CCS cell lines exist. The objective of this study was to establish patient-derived CCS models. We established patient-derived CCS models from a 43-yr-old female patient. We prepared the patient-derived xenografts (PDXs) from tumor tissues obtained through biopsy or surgery and isolated stable cell lines from PDXs and the original tumor tissue. The presence of gene fusions was examined by RT-PCR, and Sanger sequencing. The established cell lines were characterized by short tandem repeat, viability, colony and spheroid formation, and invasion analyses. Differences in gene enrichment between the primary tumor and cell lines were examined by mass spectrometry and KEGG pathway analysis. The cell lines were maintained for more than 80 passages, and had tumorigenic characteristics such as colony and spheroid formation and invasion. Mass spectrometric proteome analysis demonstrated that the cell lines were enriched for similar but distinct molecular pathways, compared to those in the xenografts and original tumor tissue. Next, tyrosine kinase inhibitors were screened for their suppressive effects on viability. We found that ponatinib, vandetanib, and doxorubicin suppressed the growth of cell lines, and had equivalent IC50 values. Further in-depth investigation and understanding of drug-sensitivity mechanisms will be important for the clinical applications of our cell lines.

Objective: To investigate the clinicopathologic and molecular characteristics, diagnostic, differential diagnostic and prognostic features of malignant gastrointestinal neuroectodermal tumor. Methods: Two cases of malignant gastrointestinal neuroectodermal tumor were retrieved; the clinical and radiologic features, histomorphology, immunophenotype, molecular genetics and prognosis were analyzed and the relevant literature reviewed. Results: Case 1 was a 57-year-old male, presented with recurrent abdominal pain and melena. Pelvic imaging showed a circumscribed thickening of the wall of a small intestinal segment, and a malignant lymphoma was favored. Case 2 was a 24-year-old male, presented with recurrent small intestinal malignancy. Imaging demonstrated multiple masses in the peritoneal and pelvic cavities, and a malignant gastrointestinal stromal tumor with multiple metastases was suspected. Grossly both tumors were located mainly in the muscularis propria of small intestine. Case 1 showed a single 5.5 cm tumor; and case 2 consisted of two tumors measuring 4 cm and 6 cm respectively. Microscopic examination of both tumors showed small round blue, but focally spindled or clear tumor cells in solid pattern. The tumor cells had scanty cytoplasm, indistinctive nucleoli and brisk mitoses. Osteoclast-like giant cells were dispersed within the stroma. In case 1 rosette-like and pseudo-papillary growth patterns were noted, and in case 2 there were variable-sized hemorrhagic cysts. By immunohistochemistry, both tumors showed strong and diffuse expression of SOX10 and S-100, and focal to diffuse expression of neuroendocrine markers (CD56 or synaptophysin). Case 2 exhibited focal reactivity to pan-cytokeratin. Both tumors lacked expression of markers associated with gastrointestinal stromal tumor, smooth muscle tumor, melanoma (HMB45 or Melan A), dendritic cell tumor and Ewing sarcoma. Fluorescence in situ hybridization analysis demonstrated EWSR1 rearrangement in both tumors and the next generation sequencing confirmed EWSR1-ATF1 gene fusion in case 2. At follow-up of 16 months, case 1 was recurrence or metastasis free; whereas case 2 showed multiple recurrences and metastases within 19 months although stable disease was transiently achieved when treated with combinations of multidrug and targeted chemotherapy. Conclusions: Malignant gastrointestinal neuroectodermal tumor is a rare and aggressive soft tissue sarcoma with a predilection for small intestine. It has distinctive morphologic, immunohistochemical and molecular characteristics and needs to be distinguished from other small blue round and spindle cell tumors that occur in the gut. Careful attentions to its characteristic histomorphology with the judicious use of immunohistochemistry and molecular genetics can help to distinguish this tumor from its many mimickers.

Clear Cell Sarcoma (CCS) is a deadly malignancy affecting adolescents and young adults. It is characterized by reciprocal translocations resulting in the expression of the chimeric EWSR1-ATF1 or EWSR1-CREB1 fusion proteins, driving sarcomagenesis. Besides these characteristics, CCS has remained genomically uncharacterized. Copy number analysis of human CCSs showed frequent amplifications of the MITF locus and chromosomes 7 and 8. Few alterations were shared with Ewing sarcoma or desmoplastic small round cell tumors, other EWSR1-rearranged tumors. Exome sequencing in mouse tumors generated by expressing EWSR1-ATF1 from the Rosa26 locus demonstrated no other repeated pathogenic variants. Additionally, we generated a new CCS mouse by Cre-loxP-induced chromosomal translocation between Ewsr1 and Atf1, resulting in copy number loss of chromosome 6 and chromosome 15 instability, including amplification of a portion syntenic with human chromosome 8, surrounding Myc. Additional experiments in the Rosa26 conditional model demonstrated that Mitf or Myc can contribute to sarcomagenesis. Copy number observations in human tumors and genetic experiments in mice render, for the first time, a functional landscape of the CCS genome. These data advance efforts to understand the biology of CCS with innovative models, in which we can eventually validate preclinical therapies, necessary to move toward longer and better survival of the young victims of this disease.

Keywords: Cancer; Genetics; Mouse models; Oncogenes; Oncology.

Malignant mesothelioma is a neoplasm of serosal surfaces, most commonly affecting the pleura. The peritoneum, pericardium, and tunica vaginalis are less frequently involved. Malignant mesothelioma with EWSR1-ATF1 fusion in young adults was recently reported in the literature. Here, we present two pediatric cases of EWSR1-ATF1 translocation-associated malignant mesothelioma in the peritoneum and pericardium respectively. Both cases lacked a known exposure history. Microscopy in both cases showed predominantly epithelioid morphology with ample eosinophilic cytoplasm, and immunohistochemistry was positive for pan-keratin, calretinin, and WT1. Both cases showed EWSR1-ATF1 gene rearrangement by RNA sequencing, which was instrumental in confirming the diagnosis of malignant mesothelioma and to exclude more common pediatric sarcomas, especially in the context of limited sampling.

Keywords: EWSR1; RNA sequencing; gene rearrangement; immunohistochemistry; mesothelioma; pericardium; peritoneum.

Short-chain esters have broad utility as flavors, fragrances, solvents, and biofuels. Controlling selectivity of ester microbial biosynthesis has been an outstanding metabolic engineering problem. Here, we present a generalizable framework to enable the de novo fermentative microbial biosynthesis of butyryl-CoA-derived designer esters (e.g., butyl acetate, ethyl butyrate, butyl butyrate) with controllable selectivity. Using the modular design principles, we generated the butyryl-CoA-derived ester pathways as exchangeable production modules compatible with an engineered chassis cell for anaerobic production of designer esters. We designed these modules derived from an acyl-CoA submodule (e.g., acetyl-CoA, butyryl-CoA), an alcohol submodule (e.g., ethanol, butanol), a cofactor regeneration submodule (e.g., NADH), and an alcohol acetyltransferase (AAT) submodule (e.g., ATF1, SAAT) for rapid module construction and optimization by manipulating replication (e.g., plasmid copy number), transcription (e.g., promoters), translation (e.g., codon optimization), pathway enzymes, and pathway induction conditions. To further enhance production of designer esters with high selectivity, we systematically screened various strategies of protein solubilization using protein fusion tags and chaperones to improve the soluble expression of multiple pathway enzymes. Finally, our engineered ester-producing strains could achieve 19-fold increase in butyl acetate production (0.64 g/L, 96% selectivity), 6-fold increase in ethyl butyrate production (0.41 g/L, 86% selectivity), and 13-fold increase in butyl butyrate production (0.45 g/L, 54% selectivity) as compared to the initial strains. Overall, this study presented a generalizable framework to engineer modular microbial platforms for anaerobic production of butyryl-CoA-derived designer esters from renewable feedstocks.

Keywords: AAT; ATF1; Alcohol acyltransferase; Butyl acetate; Butyl butyrate; Chaperones; Codon optimization; Enzyme solubilization; Escherichia coli; Esters; Ethyl butyrate; Fusion partners; Modular cell; Modular design; Modular pathway design; SAAT; Soluble expression.

It has long been known (circa 1917) that environmental conditions, as well as speciation, can affect dramatically the frequency distribution of Spo11/Rec12-dependent meiotic recombination. Here, by analyzing DNA sequence-dependent meiotic recombination hotspots in the fission yeast Schizosaccharomyces pombe, we reveal a molecular basis for these phenomena. The impacts of changing environmental conditions (temperature, nutrients, osmolarity) on local rates of recombination are mediated directly by DNA site-dependent hotspots (M26, CCAAT, Oligo-C). This control is exerted through environmental condition-responsive signal transduction networks (involving Atf1, Pcr1, Php2, Php3, Php5, Rst2). Strikingly, individual hotspots modulate rates of recombination over a very broad dynamic range in response to changing conditions. They can range from being quiescent to being highly proficient at promoting activity of the basal recombination machinery (Spo11/Rec12 complex). Moreover, each different class of hotspot functions as an independently controlled rheostat; a condition that increases the activity of one class can decrease the activity of another class. Together, the independent modulation of recombination rates by each different class of DNA site-dependent hotspots (of which there are many) provides a molecular mechanism for highly dynamic, large-scale changes in the global frequency distribution of meiotic recombination. Because hotspot-activating DNA sites discovered in fission yeast are conserved functionally in other species, this process can also explain the previously enigmatic, Prdm9-independent, evolutionarily rapid changes in hotspot usage between closely related species, subspecies, and isolated populations of the same species.

Keywords: Prdm9; Recombination; evolution; meiosis; plasticity; recombination hotspot.

Aims: Intracranial myxoid mesenchymal tumors (IMMTs) with fusions between EWSR1/FUS and CREB transcription factors have morphologic overlap with myxoid angiomatoid fibrous histiocytoma (mAFH) and myoepithelial tumor/carcinoma (MET/MEC). We aimed to study the clinicopathologic and genetic spectrum of extracranial IMMT-like tumors and their relationships with mAFH and MET/MEC.

Methods: Twelve extracranial tumors harboring EWSR1/FUS-CREB fusions across different histologic groups were characterized using RNA sequencing, FISH and/or RT-PCR.

Results: There were 4 IMMT-like neoplasms, 3 MET/MECs, and 5 mAFHs from the tibia (n=1), oral cavity (n=2), and soft tissues (n=9; 5 in the extremities), harboring EWSR1-ATF1 in 4 cases, FUS-CREM and EWSR1-CREM in 3 each, and EWSR1-CREB1 in 2. Multinodular growth, reticular/cording/trabecular arrangements, myxocollagenous matrix, and lymphocytic infiltrates variably prevailed among the 3 groups. mAFHs were characterized by cells with syncytial cytoplasm. IMMT-like neoplasms and MET/MECs shared cells with distinct boundaries, but only MET/MECs expressed GFAP and/or S100. MUC4 and ALK were expressed in some IMMT-like neoplasms (2/4; 2/4) and mAFH (2/5; 1/5). Pan-TRK reactivity was observed in two IMMT-like neoplasms with upregulated NTRK3 mRNA and one MEC. Local recurrences, typically ≥ 12 months postoperatively, developed in 2/3 IMMT-like neoplasms, 1/2 MET/MECs, and 0/4 mAFHs with follow-up. No definite associations were found between fusion types and histology, immunoprofile or outcome.

Conclusions: We demonstrated the similarities and differences among 3 extracranial myxocollagenous tumor groups sharing EWSR1/FUS-CREB fusions. Oral IMMT-like neoplasms harboring FUS-CREM or EWSR1-ATF1 and FUS-CREM-positive.

Keywords: Angiomatoid fibrous histiocytoma; CREB; Extracranial; FET; Myoepithelial; Myxocollagenous.

The ability to cope with environmental abiotic stress and biotic stress is crucial for the survival of plants and microorganisms, which enable them to occupy multiple niches in the environment. Previous studies have shown that transcription factors play crucial roles in regulating various biological processes including multiple stress tolerance and response in eukaryotes. This work identified multiple critical transcription factor genes, metabolic pathways and gene ontology (GO) terms related to abiotic stress response were broadly activated by analyzing the transcriptome of phytopathogenic fungus Alternaria alternata under metal ions stresses, oxidative stress, salt stresses, and host-pathogen interaction. We investigated the biological functions and regulatory roles of the bZIP transcriptional factor (TF) genes in the phytopathogenic fungus A.alternata by analyzing targeted gene disrupted mutants. Morphological analysis provides evidence that the bZIP transcription factors (Gcn4, MeaB, Atf1, the ER stress regulator Hac1, and the all development altered-1 gene Ada1) are required for morphogenesis as the colony morphology of these gene deletion mutants was significantly different from that of the wild-type. In addition, bZIPs are involved in the resistance to multiple stresses such as oxidative stress (Ada1, Yap1, MetR) and virulence (Hac1, MetR, Yap1, Ada1) at varying degrees. Transcriptome data demonstrated that the inactivation of bZIPs (Hac1, Atf1, Ada1 and Yap1) significantly affected many genes in multiple critical metabolism pathways and gene ontology (GO) terms. Moreover,the ΔHac1 mutants displayed reduced aerial hypha and are hypersensitivity to endoplasmic reticulum disruptors such as tunicamycin and dithiothreitol. Transcriptome analysis showed that inactivation of Hac1 significantly affected the proteasome process and its downstream unfolded protein binding, indicating that Hac1 participates in the endoplasmic reticulum stress response through the conserved unfolded protein response. Taken together, our findings reveal that bZIP transcription factors function as key regulators of fungal morphogenesis, abiotic stress response and pathogenesis, and expand our understanding of how microbial pathogens utilize these genes to deal with environmental stresses and achieve successful infection in the host plant.

Keywords: Abiotic stress response; Alternaria alternata; Endoplasmic reticulum stress; Stress-activated pathway; Transcriptome analysis; bZIP transcription factor.