Pik3r1 Is Required for Glucocorticoid-Induced Perilipin 1 Phosphorylation in Lipid Droplet for Adipocyte Lipolysis.

Glucocorticoids promote lipolysis in white adipose tissue (WAT) to adapt to energy demands under stress, whereas superfluous lipolysis causes metabolic disorders, including dyslipidemia and hepatic steatosis. Glucocorticoid-induced lipolysis requires the phosphorylation of cytosolic hormone-sensitive lipase (HSL) and perilipin 1 (Plin1) in the lipid droplet by protein kinase A (PKA). We previously identified Pik3r1 (also called p85α) as a glucocorticoid receptor target gene. Here, we found that glucocorticoids increased HSL phosphorylation, but not Plin1 phosphorylation, in adipose tissue-specific Pik3r1-null (AKO) mice. Furthermore, in lipid droplets, the phosphorylation of HSL and Plin1 and the levels of catalytic and regulatory subunits of PKA were increased by glucocorticoids in wild-type mice. However, these effects were attenuated in AKO mice. In agreement with reduced WAT lipolysis, glucocorticoid- initiated hepatic steatosis and hypertriglyceridemia were improved in AKO mice. Our data demonstrated a novel role of Pik3r1 that was independent of the regulatory function of phosphoinositide 3-kinase in mediating the metabolic action of glucocorticoids. Thus, the inhibition of Pik3r1 in adipocytes could alleviate lipid disorders caused by excess glucocorticoid exposure

Transcriptional regulation of FoxO3 gene by glucocorticoids in murine myotubes.

Glucocorticoids and FoxO3 exert similar metabolic effects in skeletal muscle. FoxO3 gene expression was increased by dexamethasone (Dex), a synthetic glucocorticoid, both in vitro and in vivo. In C2C12 myotubes the increased expression is due to, at least in part, the elevated rate of FoxO3 gene transcription. In the mouse FoxO3 gene, we identified three glucocorticoid receptor (GR) binding regions (GBRs): one being upstream of the transcription start site, -17kbGBR; and two in introns, +45kbGBR and +71kbGBR. Together, these three GBRs contain four 15-bp glucocorticoid response elements (GREs). Micrococcal nuclease (MNase) assay revealed that Dex treatment increased the sensitivity to MNase in the GRE of +45kbGBR and +71kbGBR upon 30- and 60-min Dex treatment, respectively. Conversely, Dex treatment did not affect the chromatin structure near the -17kbGBR, in which the GRE is located in the linker region. Dex treatment also increased histone H3 and/or H4 acetylation in genomic regions near all three GBRs. Moreover, using chromatin conformation capture (3C) assay, we showed that Dex treatment increased the interaction between the -17kbGBR and two genomic regions: one located around +500 bp and the other around +73 kb. Finally, the transcriptional coregulator p300 was recruited to all three GBRs upon Dex treatment. The reduction of p300 expression decreased FoxO3 gene expression and Dex-stimulated interaction between distinct genomic regions of FoxO3 gene identified by 3C. Overall, our results demonstrate that glucocorticoids activated FoxO3 gene transcription through multiple GREs by chromatin structural change and DNA looping

Characterizing the Mitochondrial Redox Relay System

The biogenesis of mitochondria depends on sophisticated import machineries to correctlytarget and fold cytosolically synthesized mitochondrial proteins. The mitochondrial import and assembly (MIA) pathway is a redox relay system that is essential for protein import into the intermembrane space (IMS) of mitochondria. It is unique that protein oxidation is tightly coupled to protein translocation. Given that the intermembrane space is highly relevant to a broad spectrum of diseases including apoptosis and neurodegeneration, additional research is needed to understand the underlying mechanism and new roles of regulation by the redox relay system. We have identified a novel protein, Aim32 that is dually localized in matrix and IMS. Aim32 is a thioredoxin-like [2Fe-2S] ferredoxin protein and binds with Erv1. Deletion of Aim32 or mutation of conserved cysteine residues resulted in an increased accumulation of proteins with aberrant disulfide linkages. In addition, the steady-state level of assembled mitochondrial protein import complexes was decreased, and a subset of the complexes showed disassembly. Aim32 also bound to several mitochondrial proteins through disulfide linkages, suggesting a function in maintaining the redox status of proteins by potentially targeting cysteine residues. These studies suggest that Aim32 may be poised as a sensor or regulator in quality control in a broad range of mitochondrial proteins. In addition to the function of ALR/Erv1 in protein translocation, it plays critical roles in various cellular pathways. We found ALR/Erv1 has an unexpected pro-survival role in hPSCs. A small molecule inhibitor that is specific for ALR/Erv1 was applied to investigate the hPSCs apoptosis and differentiation, which has the potential in hPSCs therapeutics

The Aggregation of ATAD2 Bromodomain in Solution

ATPase family AAA domain-containing protein 2 (ATAD2) is a chromatin regulator, also known as an oncogenic transcription cofactor. Its abnormal expression is closely related to the occurrence and development of various malignant tumors. ATAD2 consists of two domains: the ATPase domain and the bromodomain. The bromodomain can specifically recognize and interact with the acetylated lysines in proteins, which regulates the refactoring and transcription of chromosomes. In this work, we found that ATAD2 bromodomains are aggregated under normal solution conditions. Considering the possible impact of aggregation on the interaction between ATAD2 bromodomain and acetylated histone tail, we preliminarily investigated the aggregation of ATAD2 bromodomains mainly by nuclear magnetic resonance (NMR) and circular dichroism (CD) spectra. The results suggested that the aggregation is accompanied with structure alteration and possibly related to the physiological functions of cells. This study may provide new clues for the development of ATAD2 bromodomain inhibitors

The Different Metabolic Responses of Resistant and Susceptible Wheats to Fusarium graminearum Inoculation

Fusarium head blight (FHB) is a serious wheat disease caused by Fusarium graminearum (Fg) Schwabe. FHB can cause huge loss in wheat yield. In addition, trichothecene mycotoxins produced by Fg are harmful to the environment and humans. In our previous study, we obtained two mutants TPS1− and TPS2−. Neither of these mutants could synthesize trehalose, and they produced fewer mycotoxins. To understand the complex interaction between Fg and wheat, we systematically analyzed the metabolic responses of FHB-susceptible and -resistant wheat to ddH2O, the TPS− mutants and wild type (WT) using NMR combined with multivariate analysis. More than 40 metabolites were identified in wheat extracts including sugars, amino acids, organic acids, choline metabolites and other metabolites. When infected by Fg, FHB-resistant and -susceptible wheat plants showed different metabolic responses. For FHB-resistant wheat, there were clear metabolic differences between inoculation with mutants (TPS1−/TPS2−) and with ddH2O/WT. For the susceptible wheat, there were obvious metabolic differences between inoculation with mutant (TPS1−/TPS2−) and inoculation with ddH2O; however, there were no significant metabolic differences between inoculation with TPS− mutants and with WT. Specifically, compared with ddH2O, resistant wheat increased the levels of Phe, p-hydroxy cinnamic acid (p-HCA), and chlorogenic acid in response to TPS− mutants; however, susceptible wheat did not. Shikimate-mediated secondary metabolism was activated in the FHB-resistant wheat to inhibit the growth of Fg and reduce the production of mycotoxins. These results can be helpful for the development of FHB-resistant wheat varieties, although the molecular relationship between the trehalose biosynthetic pathway in Fg and shikimate-mediated secondary metabolism in wheat remains to be further studied

HAMP as a Potential Diagnostic, PD-(L)1 Immunotherapy Sensitivity and Prognostic Biomarker in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) remains a global medical problem. Programmed cell death protein 1 (PD-1) is a powerful weapon against many cancers, but it is not sensitive to some patients with HCC. We obtained datasets from the Gene Expression Omnibus (GEO) database on HCC patients and PD-1 immunotherapy to select seven intersecting DEGs. Through Lasso regression, two intersecting genes were acquired as predictors of HCC and PD-1 treatment prognosis, including HAMP and FOS. Logistic regression was performed to build a prediction model. HAMP had a better ability to diagnose HCC and predict PD1 treatment sensitivity. Further, we adapted the support vector machine (SVM) technique using HAMP to predict triple-classified outcomes after PD1 treatment in HCC patients, which had an excellent classification ability. We also performed external validation using TCGA data, which showed that HAMP was elevated in the early stage of HCC. HAMP was positively correlated with the infiltration of 18 major immune cells and the expression of 2 important immune checkpoints, PDCD1 and CTLA4. We discovered a biomarker that can be used for the early diagnosis, prognosis and PD1 immunotherapy efficacy prediction of HCC for the first time and developed a diagnostic model, prognostic model and prediction model of PD1 treatment sensitivity and treatment outcome for HCC patients accordingly