Structural insight into the TRIAP1/PRELI-like domain family of mitochondrial phospholipid transfer complexes

The composition of the mitochondrial membrane is important for its architecture and proper function. Mitochondria depend on a tightly regulated supply of phospholipid via intra-mitochondrial synthesis and by direct import from the endoplasmic reticulum. The Ups1/PRELI-like family together with its mitochondrial chaperones (TRIAP1/Mdm35) represent a unique heterodimeric lipid transfer system that is evolutionary conserved from yeast to man. Work presented here provides new atomic resolution insight into the function of a human member of this system. Crystal structures of free TRIAP1 and the TRIAP1–SLMO1 complex reveal how the PRELI domain is chaperoned during import into the intermembrane mitochondrial space. The structural resemblance of PRELI-like domain of SLMO1 with that of mammalian phoshatidylinositol transfer proteins (PITPs) suggest that they share similar lipid transfer mechanisms, in which access to a buried phospholipid-binding cavity is regulated by conformationally adaptable loops

Lapatinib sensitivity in nasopharyngeal carcinoma is modulated by SIRT2-mediated FOXO3 deacetylation [version 3]

Background Chemoresistance is an obstacle to the successful treatment of nasopharyngeal carcinoma (NPC). Lapatinib is a targeted tyrosine kinase inhibitor therapeutic drug also used to treat NPC, but high doses are often required to achieve a result. To investigate the mechanism for the development of Lapatinib resistance, we characterised a number of NPC cell lines to determine the role of FOXO3 and sirtuins in regulating NPC resistance. Methods Sulforhodamine B (SRB) assays, Clonogenic assays, Protein extraction, quantification and western blotting, RT qPCR, Co-immunoprecipitation assay Results To explore novel treatment strategies, we first characterized the Lapatinib-sensitivity of a panel of NPC cell lines by SRB and clonogenic cytotoxic assays and found that the metastatic NPC (C666-1 and 5-8F) cells are highly resistant whereas the poorly metastatic lines (6-10B, TW01 and HK-1)are sensitive to Lapatinib. Western blot analysis of the Lapatinib-sensitive 6-10Band resistant 5-8FNPC cells showed that the expression of phosphorylated/inactive FOXO3 (P-FOXO3;T32), its target FOXM1 and its regulator SIRT2 correlate negatively with Lapatinib response and sensitivity, suggesting that SIRT2 mediates FOXO3 deacetylation to promote Lapatinib resistance. In agreement, clonogenic cytotoxic assays using wild-type and foxo1/3/4 −/− mouse embryonic fibroblasts (MEFs) showed that FOXO1/3/4-deletion significantly attenuates Lapatinib-induced cytotoxicity, confirming that FOXO proteins are essential for mediating Lapatinib response. SRB cell viability assays using chemical SIRT inhibitors (i.e. sirtinol, Ex527, AGK2 and AK1) revealed that all SIRT inhibitors can reduce NPC cell viability, but only the SIRT2-specific inhibitors AK1 and AGK2 further enhance the Lapatinib cytotoxicity. Consistently, clonogenic assays demonstrated that the SIRT2 inhibitors AK1 and AGK2 as well as SIRT2-knockdown increase Lapatinib cytotoxicity further in both the sensitive and resistant NPC cells. Co-immunoprecipitation studies showed that besides Lapatinib treatment, SIRT2-pharmaceutical inhibition and silencing also led to an increase in FOXO3 acetylation. Importantly, SIRT2 inhibition and depletion further enhanced Lapatinib-mediated FOXO3-acetylation in NPC cells. Conclusion Collectively, our results suggest the involvement of SIRT2-mediated FOXO3 deacetylation in Lapatinib response and sensitivity, and that SIRT2 can specifically antagonise the cytotoxicity of Lapatinib through mediating FOXO3 deacetylation in both sensitive and resistant NPC cells

FOXA1 is a determinant of drug resistance in breast cancer cells

Purpose Breast cancer is one of the most commonly diagnosed cancers in women. Five subtypes of breast cancer differ in their genetic expression profiles and carry different prognostic values, with no treatments available for some types, such as triple-negative, due to the absence of genetic signatures that could otherwise be targeted by molecular therapies. Although endocrine treatments are largely successful for estrogen receptor (ER)-positive cancers, a significant proportion of patients with metastatic tumors fail to respond and acquire resistance to therapy. FOXA1 overexpression mediates endocrine therapy resistance in ER-positive breast cancer, although the regulation of chemotherapy response by FOXA1 has not been addressed previously. FOXA1, together with EP300 and RUNX1, regulates the expression of E-cadherin, and is expressed in luminal, but absent in triple-negative and basal-like breast cancers. We have previously determined that EP300 regulates drug resistance and tumor initiation capabilities in breast cancer cells. Methods Here we describe the generation of breast cancer cell models in which FOXA1 expression has been modulated either by expression of hairpins targeting FOXA1 mRNA or overexpression plasmids. Results Upon FOXA1 knockdown in luminal MCF-7 and T47D cells, we found an increase in doxorubicin and paclitaxel sensitivity as well as a decrease in anchorage independence. Conversely, upregulation of FOXA1 in basal-like MDA-MB-231 cells led to an increase in drug resistance and anchorage independence. Conclusion Together, these data suggest that FOXA1 plays a role in making tumors more aggressive

Cardiovascular safety profile of romosozumab: a pharmacovigilance analysis of the US Food and Drug Administration Adverse Event Reporting System (FAERS)

Background: Cardiovascular safety concerns for major cardiovascular events (MACE) were raised during the clinical trials of romosozumab. We aimed to evaluate the cardiovascular safety profile of romosozumab in a large pharmacovigilance database. Methods: All cases reported between January 2019 and December 2020 where romosozumab was reported were extracted from the Food and Drug Administration Adverse Event Reporting System (FAERS). The outcome of interest was MACE (myocardial infarction (MI), stroke, or cardiovascular death). A disproportionality analysis was conducted by estimating the reporting odds ratios (RORs) and 95% confidence intervals. Disproportionality analyses were stratified by sex and reporting region (US, Japan, other). Results: Of the 1995 eligible cases with romosozumab, the majority (N = 1188; 59.5%) originated from Japan. Overall, 206 suspected MACE reports were identified, of which the majority (n = 164; 13.8%) were from Japan, and 41 (5.2%) were from the United States (US). Among Japanese reports, patients were older and more frequently male than reports from the US. Similarly, cases with a reported MACE were older and had higher reports of cardioprotective drugs than those without cardiovascular events. Elevated reports for MACE (ROR 4.07, 95% CI: 2.39-6.93) was identified overall, which was primarily driven by the significant disproportionality measures in the Japanese reports. Conclusions: The current pharmacovigilance study identified a potential signal for elevated MACE, particularly in Japan. The results support the current safety warnings from the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) to avoid use in high-risk patients.Diabetes mellitus: pathophysiological changes and therap

Short and Long Term Variation in Ultraviolet Radiation and Multiple Sclerosis

We examined the role of ultraviolet radiation (UVR) in persons diagnosed with multiple sclerosis (MS) in four different populations, Italians, Danish, White and African Americans. We tested whether variation in UVR as determined by seasons (short term variation) and solar cycles (long term variation) is related to MS birth month and to survival as measured by lifespan. Cases were selected from three Italian MS Case Registries (2,737); from the United States National Center for Health Statistics (56,020); and from the Danish Multiple Sclerosis registry (15,900). Chi-square tests were used to study the pattern of month of birth distribution in patients with MS comparing with general population data. T-tests were employed to study solar cycles association with lifespan. A surplus of births was observed in June for White Americans. A decrease of births in October and November, though not significant after multiple testing correction, was observed in the three populations. In White American with MS overall, males and females, we found that solar cycle is associated with lifespan. We found that season and solar cycles have some role in MS susceptibility and life duration. However, this is an exploratory analysis and further work is needed to discern the association

Low-Density Lipoprotein Has an Enormous Capacity To Bind (E)-4-Hydroxynon-2-enal (HNE): Detection and Characterization of Lysyl and Histidyl Adducts Containing Multiple Molecules of HNE

(E)-4-Hydroxynon-2-enal (HNE), an electrophilic bifunctional cytotoxic lipid peroxidation product, forms covalent adducts with nucleophilic side chains of amino acid residues. HNE-derived adducts have been implicated in many pathophysiological processes including atherosclerosis, diabetes, and Alzheimer’s disease. Tritium- and deuterium-labeled HNE (d4-HNE) were used orthogonally to study adduction with proteins and individual nucleophilic groups of histidyl, lysyl, and cysteine residues. Using tritium-labeled HNE, we detected the binding of 486 molecules of HNE per low-density lipoprotein (LDL) particle, significantly more than the total number of all reactive nucleophiles in the LDL particle. This suggests the formation of adducts that incorporate multiple molecules of HNE with some nucleophilic amino acid side chains. We also found that the reaction of a 1:1 mixture of d4-HNE and d0-HNE with N-acetylhistidine, N-acetyl-Gly-Lys-OMe, or N-acetyl cysteine generates 1:1, 2:1, and 3:1 adducts, which exhibit unique mass spectral signatures that aid in structural characterization. A domino-like reaction of initial 1:1 HNE Michael adducts of histidyl or lysyl nucleophiles with multiple additional HNE molecules forms 2:1 and 3:1 adducts that were structurally characterized by tandem mass spectrometry