BACKGROUND: Podocyte senescence causes podocyte loss and glomerulopathy. Excessive fructose intake is a risk factor for podocyte injury. However, whether high fructose promotes podocyte senescence remains unknown.
OBJECTIVE: To explore the pathological mechanism by which high fructose drives podocyte senescence and find natural compounds to alleviate podocyte senescence.
METHODS: Podocyte senescence was characterized with senescence-associated beta-galactosidase (SA-β-gal) staining, Western blot, real-time quantitative polymerase chain reaction (qRT-PCR), comet assay and immunofluorescence. Proteomics analysis was performed to identify differentially expressed proteins in high fructose-exposed podocytes. Podocyte nuclear pore complexes (NPCs) and foot processes were observed by transmission electron microscopy. The mRNA and protein levels of nucleoporin 155 (Nup155) and inositol requiring mutant 80 (INO80) were detected by qRT-PCR, Western blot and immunofluorescence. Virtual screening was conducted to find natural compounds that target Nup155.
RESULTS: High fructose increased SA-β-gal activity, protein level of p53, p21, p16 and phosphorylated histone H2AX (γ-H2AX), as well as mRNA expression of interleukin-1β (IL-1β), IL-6 and tumor necrosis factor α (TNF-α) in rat glomeruli and podocytes. Proteomic analysis unraveled a crucial molecule Nup155, which was decreased in high fructose-induced podocyte senescence. Meanwhile, the number of podocyte NPCs was also decreased in vivo and in vitro. Consistently, high fructose suppressed nuclear export of INO80 mRNA, thereby down-regulated INO80 protein expression in podocyte senescence. Deletion of Nup155 inhibited INO80 mRNA nuclear export to induce podocyte senescence, whereas overexpression of Nup155 or INO80 alleviated high fructose-induced podocyte senescence. Ferulic acid was found to up-regulate Nup155 by both direct binding to stabilize Nup155 protein and enhancing its transcription, to promote INO80 mRNA nuclear export in the mitigation of high fructose-caused podocyte senescence.
CONCLUSIONS: High fructose induces podocyte senescence by decreasing Nup155 to inhibit INO80 mRNA nuclear export. Ferulic acid targeting Nup155 may be a potential strategy to prevent high fructose-induced podocyte senescence.

The aberrant function of ATP-dependent chromatin remodeler INO80 has been implicated in multiple types of cancers by altering chromatin architecture and gene expression; however, the underlying mechanism of the functional involvement of INO80 mutation in cancer etiology, especially in breast cancer, remains unclear. In the present study, we have performed a weighted gene co-expression network analysis (WCGNA) to investigate links between INO80 expression and breast cancer sub-classification and progression. Our analysis revealed that INO80 repression is associated with differential responsiveness of estrogen receptors (ERs) depending upon breast cancer subtype, ER networks, and increased risk of breast carcinogenesis. To determine whether INO80 loss induces breast tumors, a conditional INO80-knockout (INO80 cKO) mouse model was generated using the Cre-loxP system. Phenotypic characterization revealed that INO80 cKO led to reduced branching and length of the mammary ducts at all stages. However, the INO80 cKO mouse model had unaltered lumen morphology and failed to spontaneously induce tumorigenesis in mammary gland tissue. Therefore, our study suggests that the aberrant function of INO80 is potentially associated with breast cancer by modulating gene expression. INO80 mutation alone is insufficient for breast tumorigenesis.

Taf14 is a subunit of multiple fundamental complexes implicated in transcriptional regulation and DNA damage repair in yeast cells. Here, we investigate the association of Taf14 with the consensus sequence present in other subunits of these complexes and describe the mechanistic features that affect this association. We demonstrate that the precise molecular mechanisms and biological outcomes underlying the Taf14 interactions depend on the accessibility of binding interfaces, the ability to recognize other ligands, and a degree of sensitivity to temperature and chemical and osmotic stresses. Our findings aid in a better understanding of how the distribution of Taf14 among the complexes is mediated.

Autophagy is a catabolic process to maintain homeostasis, and involved in cell differentiation and development. Autophagy is tightly regulated in response to nutrient availability but the underlying mechanism is not completely understood. Recently, we identified the chromatin remodeling complex INO80 (inositol-requiring mutant 80) and histone variant H2A.Z as new autophagy regulators and uncover how histone deacetylase Rpd3L (reduced potassium dependency 3 large) complex represses autophagy by deacetylating Ino80 and H2A.Z. In particular, Rpd3L complex deacetylates Ino80 at lysine 929, which protects Ino80 from being degraded by autophagy. The stabilized Ino80 then evicts H2A.Z from autophagy-related (ATG) genes, leading to their transcriptional repression. In parallel, Rpd3L complex also deacetylates H2A.Z, which further reduces its association with ATG gene promoters and repress ATG gene transcription. Under nutrient-rich conditions, Rpd3L-mediated deacetylation of Ino80 K929 and H2A.Z is enhanced by the TORC1 complex (target of rapamycin complex 1). Under nitrogen-starvation condition, TORC1 is inactivated, leading to reduced activity of Rpd3L complex and increased acetylation of Ino80 and H2A.Z, which in turn induce the transcription of ATG genes. These results reveal a critical role of chromatin remodelers and histone variants in regulating autophagy in response to nutrient availability.Abbreviations: INO80: inositol-requiring mutant 80; Rpd3: reduced potassium dependency 3; H2A.Z: histone H2A variant; Rpd3L complex: Rpd3 large complex; H4K16: H4 lysine 16; H3R17: H3 arginine 17; H3T11: H3 threonine 11; TORC1 complex: target of rapamycin complex 1; ATG: autophagy-related; SWI/SNF: switch/sucrose non-fermentable; SWR1: Swi2/Snf2-related ATPase complex; RSC: remodel the structure of chromatin; ISWI: imitation switch; CHD1: chromodomain helicase DNA binding protein 1; Arp8: actin-related protein 8; Sds3: suppressor of defective silencing 3; Ume6: unscheduled meiotic gene expression 6.

Plants can sense temperature changes and adjust their development and morphology accordingly in a process called thermomorphogenesis. This phenotypic plasticity implies complex mechanisms regulating gene expression reprogramming in response to environmental alteration. Histone variants often associate with specific chromatin states; yet, how their deposition/eviction modulates transcriptional changes induced by environmental cues remains elusive. In Arabidopsis thaliana, temperature elevation-induced transcriptional activation at thermo-responsive genes entails the chromatin eviction of a histone variant H2A.Z by INO80, which is recruited to these loci via interacting with a key thermomorphogenesis regulator PIF4. Here, we show that both INO80 and the deposition chaperones of another histone variant H3.3 associate with ELF7, a critical component of the transcription elongator PAF1 complex. H3.3 promotes thermomorphogenesis and the high temperature-enhanced RNA Pol II transcription at PIF4 targets, and it is broadly required for the H2A.Z removal-induced gene activation. Reciprocally, INO80 and ELF7 regulate H3.3 deposition, and are necessary for the high temperature-induced H3.3 enrichment at PIF4 targets. Our findings demonstrate close coordination between H2A.Z eviction and H3.3 deposition in gene activation induced by high temperature, and pinpoint the importance of histone variants dynamics in transcriptional regulation.

Precise regulation of the cell cycle of embryonic stem cells (ESCs) is critical for their self-maintenance and differentiation. The cell cycle of ESCs differs from that of somatic cells and is different depending on the cell culture conditions. However, the cell cycle regulation in ESCs via epigenetic mechanisms remains unclear. Here, we showed that the ATP-dependent chromatin remodeler Ino80 regulates the cell cycle genes in ESCs under primed conditions. Ino80 loss led to a significantly extended length of the G1-phase in ESCs grown under primed culture conditions. Ino80 directly bound to the transcription start site and regulated the expression of cell cycle-related genes. Furthermore, Ino80 loss induced cell apoptosis. However, the regulatory mechanism of Ino80 in differentiating ESC cycle slightly differed; an extended S-phase was detected in differentiating inducible Ino80 knockout ESCs. RNA-seq analysis of differentiating ESCs revealed that the expression of genes associated with organ development cell cycle is persistently altered in Ino80 knockout cells, suggesting that cell cycle regulation by Ino80 is not limited to undifferentiated ESCs. Therefore, our study establishes the function of Ino80 in ESC cycle via transcriptional regulation, at least partly. Moreover, this Ino80 function may be universal to other cell types.

ATP-dependent chromatin remodeling complexes play important roles in many essential cellular processes, including transcription regulation, DNA replication, and repair. Evicting H2A.Z, a variant of histone H2A, from the promoter of hypha-specific genes is required for hyphal formation in Candida albicans. However, the mechanism that regulates H2A.Z removal during hyphal formation remains unknown. In this study, we demonstrated that Ino80, the core catalytic subunit of the INO80 complex, was recruited to hypha-specific promoters during hyphal induction in Arp8 dependent manner and facilitated the removal of H2A.Z. Deleting INO80 or mutating the ATPase site of Ino80 impairs the expression of hypha-specific genes (HSGs) and hyphal development. In addition, we showed that Ino80 was essential for the virulence of C. albicans during systemic infections in mice. Interestingly, Arp5, an INO80 complex-specific component, acts in concert with Ino80 during DNA damage responses but is dispensable for hyphal induction. Our findings clarified that Ino80 was critical for hyphal development, DNA damage response, and pathogenesis in C. albicans.

The INO80 chromatin remodeling complex plays an essential role in the regulation of gene transcription, which participate in a variety of important biological processes in cells including DNA repair and DNA replication. Difference from the yeast INO80 complex, metazoan INO80 complex have the specific subunit G, which is known as nuclear factor related to kappaB binding protein (NFRKB). Recently, NFRKB has been received much attention in many aspects, such as DNA repair, cell pluripotency, telomere protection, and protein activity regulation. To dig the new function of metazoan INO80 complex, a better understanding of the role of NFRKB is required. In this review, we provide an overview of the structure and function of NFRKB and discuss its potential role in cancer treatment and telomere regulation. Overall, this review provides an important reference for further research of the INO80 complex and NFRKB.

Adenosine triphosphate-dependent chromatin remodeling complexes are important for the regulation of transcription, DNA replication, and genome stability in eukaryotes. Although genetic studies have illustrated various biological functions of core and accessory subunits of chromatin-remodeling complexes in plants, the identification and characterization of chromatin-remodeling complexes in plants is lagging behind that in yeast and animals. Recent studies determined whether and how the Arabidopsis SWI/SNF, ISWI, INO80, SWR1, and CHD chromatin remodelers function in multi-subunit complexes in Arabidopsis. Both conserved and plant-specific subunits of chromatin-remodeling complexes have been identified and characterized. These findings provide a basis for further studies of the molecular mechanisms by which the chromatin-remodeling complexes function in plants.

Inositol requiring mutant 80 (INO80) is a chromatin remodeler that regulates pluripotency maintenance of embryonic stem cells and reprogramming of somatic cells into pluripotent stem cells. However, the roles and mechanisms of INO80 in porcine pre-implantation embryonic development remain largely unknown. Here, we show that INO80 modulates trophectoderm epithelium permeability to promote porcine blastocyst development. The INO80 protein is highly expressed in the nuclei during morula-to-blastocyst transition. Functional studies revealed that RNA interference (RNAi)-mediated knockdown of INO80 severely blocks blastocyst formation and disrupts lineage allocation between the inner cell mass and trophectoderm. Mechanistically, single-embryo RNA sequencing revealed that INO80 regulates multiple genes, which are important for lineage specification, tight junction assembly, and fluid accumulation. Consistent with the altered expression of key genes required for tight junction assembly, a permeability assay showed that paracellular sealing is defective in the trophectoderm epithelium of INO80 knockdown blastocysts. Importantly, aggregation of 8-cell embryos from the control and INO80 knockdown groups restores blastocyst development and lineage allocation via direct complementation of the defective trophectoderm epithelium. Taken together, these results demonstrate that INO80 promotes blastocyst development by regulating the expression of key genes required for lineage specification, tight junction assembly, and fluid accumulation.
INO80蛋白是一种染色质重塑因子，参与调控胚胎干细胞多能性的维持以及体细胞诱导为多能干细胞的重编程过程。然而，INO80在猪着床前胚胎发育中的作用及机制尚不清楚。该研究中，我们证实INO80调节滋养层细胞的渗透能力以促进猪囊胚发育。在桑椹胚向囊胚转变过程，INO80蛋白在胚胎细胞核中呈高表达。功能研究证明RNA干扰介导的INO80敲低导致囊胚形成失败，并破坏囊胚中内细胞团和滋养层细胞谱系的分布。单胚胎RNA测序分析揭示INO80调控许多与囊胚细胞谱系分化、紧密连接组装和囊胚腔液体积累等基因的表达。细胞渗透性分析证实INO80敲低囊胚滋养层细胞之间的细胞封闭发生缺陷。对照组和INO80敲低组8-细胞胚胎的聚合试验表明，通过补偿缺陷型滋养层细胞可以诱导INO80敲低胚胎发育成囊胚并恢复正常的细胞谱系分布。因此，以上研究结果证明染色质重塑因子INO80通过调控细胞谱系特化、紧密连接组装和液体聚集等关键基因的表达以促进囊胚发育。.