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Extrachromosomal circular DNA elements (eccDNAs) have been described in the literature for several decades, and are known for their broad existence across different species.sup.1,2. However, their biogenesis and functions are largely unknown. By developing a new circular DNA enrichment method, here we purified and sequenced full-length eccDNAs with Nanopore sequencing. We found that eccDNAs map across the entire genome in a close to random manner, suggesting a biogenesis mechanism of random ligation of genomic DNA fragments. Consistent with this idea, we found that apoptosis inducers can increase eccDNA generation, which is dependent on apoptotic DNA fragmentation followed by ligation by DNA ligase 3. Importantly, we demonstrated that eccDNAs can function as potent innate immunostimulants in a manner that is independent of eccDNA sequence but dependent on eccDNA circularity and the cytosolic DNA sensor Sting. Collectively, our study not only revealed the origin, biogenesis and immunostimulant function of eccDNAs but also uncovered their sensing pathway and potential clinical implications in immune response. By developing a new eccDNA purification and profiling method, the study revealed close-to-random genomic origination, mechanism of biogenesis and function of eccDNAs., Author(s): Yuangao Wang [sup.1] [sup.2] , Meng Wang [sup.1] [sup.2] , Mohamed Nadhir Djekidel [sup.1] [sup.2] , Huan Chen [sup.1] [sup.2] , Di Liu [sup.3] [sup.4] , Frederick W. Alt [...]

Byline: Fengjuan. Li, Hongquan. Chen, Xiaoou. Lu Nuclear factor of activated T-cells, cytoplasmic 4 (NFATC4) has been implicated in keratinocyte development and several types of cancer. A well-defined role for [...]

Mutation in the LMNA gene, encoding lamin A/C, causes a diverse group of diseases called laminopathies. Cardiac involvement is the major cause of death and manifests as dilated cardiomyopathy, heart failure, arrhythmias, and sudden death. There is no specific therapy for LMNA-associated cardiomyopathy. We report that deletion of Lmna in cardiomyocytes in mice leads to severe cardiac dysfunction, conduction defect, ventricular arrhythmias, fibrosis, apoptosis, and premature death within 4 weeks. The phenotype is similar to LMNA-associated cardiomyopathy in humans. RNA sequencing, performed before the onset of cardiac dysfunction, led to identification of 2338 differentially expressed genes (DEGs) in Lmna-deleted cardiomyocytes. DEGs predicted activation of bromodomain-containing protein 4 (BRD4), a regulator of chromatin-associated proteins and transcription factors, which was confirmed by complementary approaches, including chromatin immunoprecipitation sequencing. Daily injection of JQ1, a specific BET bromodomain inhibitor, partially reversed the DEGs, including those encoding secretome; improved cardiac function; abrogated cardiac arrhythmias, fibrosis, and apoptosis; and prolonged the median survival time 2-fold in the myocyte-specific Lmna-deleted mice. The findings highlight the important role of LMNA in cardiomyocytes and identify BET bromodomain inhibition as a potential therapeutic target in LMNA-associated cardiomyopathy, for which there is no specific effective therapy., Introduction Heart failure is a major cause of morbidity and mortality in the world (1, 2). It affects an estimated 26 million people worldwide and more than 10% of the [...]

The transcription factor ISL1 is expressed in pituitary gland stem cells and the thyrotrope and gonadotrope lineages. Pituitaryspecific Isl1 deletion causes hypopituitarism with increased stem cell apoptosis, reduced differentiation of thyrotropes and gonadotropes, and reduced body size. Conditional Isl1 deletion causes development of multiple Rathke's cleft-like cysts, with 100% penetrance. Foxa1 and Foxj1 are abnormally expressed in the pituitary gland and associated with a ciliogenic gene-expression program in the cysts. We confirmed expression of FOXA1, FOXJ1, and stem cell markers in human Rathke's cleft cyst tissue, but not craniopharyngiomas, which suggests these transcription factors are useful, pathological markers for diagnosis of Rathke's cleft cysts. These studies support a model whereby expression of ISL1 in pituitary progenitors drives differentiation into thyrotropes and gonadotropes and without it, activation of FOXA1 and FOXJ1 permits development of an oral epithelial cell fate with mucinous cysts. This pituitary-specific Isl1 mouse knockout sheds light on the etiology of Rathke's cleft cysts and the role of ISL1 in normal pituitary development., Introduction The pituitary gland forms from an evagination of neural ectoderm that forms the posterior lobe and an invagination of oral ectoderm called Rathke's pouch, which gives rise to the [...]

* Autoimmune lymphoproliferative syndrome (ALPS) is an inherited nonmalignant lymphoproliferative disorder characterized by heterozygous mutations within the first apoptosis signal receptor (FAS) signaling pathway. Defects in FAS-mediated apoptosis cause an expansion and accumulation of autoreactive [CD4.sup.-] and [CD8.sup.-] (double-negative) T cells, leading to cytopenias, splenomegaly, lymphadenopathy, autoimmune disorders, and a greatly increased lifetime risk of lymphoma. The differential diagnosis of ALPS includes infection, other inherited immunodeficiency disorders, primary and secondary autoimmune syndromes, and lymphoma. The most consistent pathologic feature is a florid paracortical expansion of double-negative T cells in lymph nodes. A presumptive clinical diagnosis can be made from symptoms and a constellation of laboratory test results. However, a definitive diagnosis requires ancillary testing and enables disease subclassification. Recognition of ALPS is critical, as treatment with immunosuppressive therapies can effectively reduce or ameliorate symptoms for most patients. (Arch Pathol Lab Med. 2020;144:245-251; doi: 10.5858/arpa.2018-0190-RS), The first apoptosis signal receptor (FAS) pathway regulates apoptosis and is critical for proper development and functioning of the immune system. (1) Autoimmune lymphoproliferative syndrome (ALPS) is an inherited lymphoproliferative [...]

Activation of RIPK1 controls TNF-mediated apoptosis, necroptosis and inflammatory pathways.sup.1. Cleavage of human and mouse RIPK1 after residues D324 and D325, respectively, by caspase-8 separates the RIPK1 kinase domain from the intermediate and death domains. The D325A mutation in mouse RIPK1 leads to embryonic lethality during mouse development.sup.2,3. However, the functional importance of blocking caspase-8-mediated cleavage of RIPK1 on RIPK1 activation in humans is unknown. Here we identify two families with variants in RIPK1 (D324V and D324H) that lead to distinct symptoms of recurrent fevers and lymphadenopathy in an autosomal-dominant manner. Impaired cleavage of RIPK1 D324 variants by caspase-8 sensitized patients' peripheral blood mononuclear cells to RIPK1 activation, apoptosis and necroptosis induced by TNF. The patients showed strong RIPK1-dependent activation of inflammatory signalling pathways and overproduction of inflammatory cytokines and chemokines compared with unaffected controls. Furthermore, we show that expression of the RIPK1 mutants D325V or D325H in mouse embryonic fibroblasts confers not only increased sensitivity to RIPK1 activation-mediated apoptosis and necroptosis, but also induction of pro-inflammatory cytokines such as IL-6 and TNF. By contrast, patient-derived fibroblasts showed reduced expression of RIPK1 and downregulated production of reactive oxygen species, resulting in resistance to necroptosis and ferroptosis. Together, these data suggest that human non-cleavable RIPK1 variants promote activation of RIPK1, and lead to an autoinflammatory disease characterized by hypersensitivity to apoptosis and necroptosis and increased inflammatory response in peripheral blood mononuclear cells, as well as a compensatory mechanism to protect against several pro-death stimuli in fibroblasts. A dominantly inherited human autoinflammatory disease caused by mutations in RIPK1 is identified, and RIPK1 mutations that prevent caspase-8 cleavage sensitize cells to apoptosis, necroptosis and inflammation., Author(s): Panfeng Tao [sup.1] , Jinqiao Sun [sup.2] , Zheming Wu [sup.3] , Shihao Wang [sup.1] , Jun Wang [sup.1] , Wanjin Li [sup.4] , Heling Pan [sup.3] , Renkui [...]

PLAC8 is a cysteine-rich protein described as a central mediator of tumor evolution in mammals; as such, it represents a promising candidate for diagnostic and therapeutic targeting. The human PLAC8 gene is also involved in contact hypersensitivity response and presents a role in psoriatic skin. In plants, PLAC8 motif-containing proteins are involved in the determination of organ size and growth, response to infection, [Ca.sup.2+] influx, Cd resistance, and zinc detoxification. In general, PLAC8 motif-containing proteins present the conserved CCXXXXCPC or CLXXXXCPC region. However, there is no devised nomenclature for the PLAC8 motif-containing proteins. Here, through the analysis of 445 sequences, we show that PLAC8 motif-containing proteins constitute a unique gene family, and we propose a unified nomenclature. This is the first report indicating the existence of different groups of PLAC8 proteins, which we have called types I, II, and III. Type I genes are found in mammals, fungi, plants, and algae, and types II and III are exclusive to plants. Our study describes for the first time PLAC8 type III proteins. Whether these sequences maintain their known functional role or possess distinct functions of types I and II genes remains unclear.Key words: PLAC8 genes, phylogenetic reconstruction, programmed cell death, cell differentiation, cysteine-rich proteins.La proteine PLAC8 est une proteine riche en cysteines et constitue un mediateur central de l'evolution des tumeurs chez les mammiferes; a ce titre, elle represente une cible prometteuse en matiere de diagnostic et de therapie. Le gene PLAC8 joue egalement un role dans l'hypersensibilite au contact et est implique dans le psoriasis. Chez les plantes, les proteines a motifs PLAC sont impliquees dans la determination de la taille et de la croissance des organes, la reponse aux infections, l'influx de [Ca.sup.2+], la resistance au Cd et la detoxication au zinc. En general, les proteines a motifs PLAC8 presentent une region conservee CCXXXXCPC ou CLXXXXCPC. Cependant, il n'y a aucune nomenclature pour les proteines a motifs PLAC. Dans ce travail, au terme d'une analyse de 445 sequences, les auteurs montrent que les proteines a motifs PLAC forment une famille de genes unique et proposent une nomenclature unifiee. Il s'agit de la premiere description de l'existence de differents groupes de proteines PLAC, lesquelles ont ete classifiees en types I, II et III. Les genes du type I sont retrouves chez les mammiferes, les champignons, les plantes et les algues, tandis que les types II et III sont uniques aux plantes. Les auteurs decrivent pour la premiere fois les proteines PLAC de type III. Il demeure inconnu si ces sequences jouent les memes roles ou s'ils possedent des fonctions differentes de celles jouees par les genes des types I et II. [Traduit par la Redaction]Mots-cles : genes PLAC8, reconstruction phylogenetique, mort cellulaire programmee, differentiation cellulaire, proteines riches en cysteine., IntroductionProgrammed cell death (PCD) is a genetically regulated process of cellular suicide that plays a fundamental role in a variety of developmental and physiological processes, removing infected or damaged cells [...]

Acute myeloid leukemia (AML) has a 5-year survival rate of only about 30%-40% due to the self-renewal and differentiation ability of leukemia stem-like cells (LSCs). To address the potential for novel therapeutic targets in LSCs, we investigated the roles of miRNA-126 and tumor necrosis factor receptor-associated factor 7 (TRAF7) in AML. We used qRT-PCR and Western blot to investigate the expression levels of miRNA-126 and TRAF7 in AML cell lines. Then, we uncovered the effect of miRNA-126 on AML cell proliferation and apoptosis by MTT assay and flow cytometric analysis, respectively. Furthermore, dual-luciferase assay and Western blot were used to determine the target of miRNA-126 in AML and the potential mechanism by which cell apoptosis is suppressed by miRNA-126. We found that miRNA-126 was highly expressed in all of the AML cell lines, and that inhibition of miRNA-126 significantly induced cell death through apoptosis. The suppression of apoptosis in AML with high expression of miRNA-126 was caused by down-regulating TRAF7, which blocked the c-FLIP pathway. The role of miRNA-126 in AML makes it a potential therapeutic target to improve clinical outcomes for patients with AML.Key words: acute myeloid leukemia cells, miRNA-126, TRAF7, apoptosis.La leucemie myeloide aigue (LMA) presente un taux de survie apres 5 ans de 30-40 % seulement, a cause de la capacite des cellules leucemiques ressemblant aux cellules souches (CSL) a s'autorenouveler et a se differencier. Afin d'identifier de nouvelles cibles therapeutiques dans les CSL, les auteurs ont examine le role du miARN-126 et de TRAF7 dans la LMA. Ils ont utilise la qRT-PCR et le transfert de Western pour examiner le niveau d'expression du miARN-126 et de TRAF7 dans des lignees de LMA. Ils ont ensuite determine l'effet du miARN-126 sur la proliferation et l'apoptose des cellules de LMA par un dosage au MTT et une analyse en cytometrie de flux, realises de maniere independante. De plus, le dosage de l'activite d'un double rapporteur luciferase et le transfert de Western ont ete utilises pour determiner les cibles du miARN-126 dans la LMA et les mecanismes d'action possibles de la suppression de l'apoptose par le miARN-126. Les auteurs ont trouve que le miARN-126 est fortement exprime dans toutes les lignees de LMA et que l'inhibition du miARN-126 provoquait la mort cellulaire par apoptose. La suppression de l'apoptose des cellules de LMA qui expriment fortement le miARN-126 etait provoquee par la regulation a la baisse de TRAF-7, qui bloquait la voie de c-FLIP. Le role du miARN-126 dans la LMA en fait une cible therapeutique potentielle pour des resultats cliniques favorables. [Traduit par la Redaction]Mots-cles: cellules de leucemie myeloide aigue, miARN-126, TRAF7, apoptose., IntroductionAcute myeloid leukemia (AML) is a life-threating disease that is associated with extremely heterogeneous disorder at all levels, including molecular, cytogenetic, cellular, and clinical (Lowenberg 2008; Metzeler et al. 2013). [...]

Byline: Ke. Zhang, Qun. Lv, Liming. Li, Mingjun. Jiang, Fang. Fang Background: Frizzled 4 (FZD4) is an important receptor for Wnt proteins that stimulate several downstream signaling pathways. It has [...]