👤 Steven W Barger

Apolipoprotein E (ApoE), reelin, and several other proteins bind ApoE-receptor 2 (apoER2), distinguished from other members of its receptor family by signal transduction which enhances the activity of N-methyl D-aspartate (NMDA) receptors. Evidence indicates that this signal transduction depends upon apoER2 forming dimers or other high-order clusters. It seems noteworthy therefore that protein products of major We examined calcium fluxes via the NMDA receptor in neurons derived from the NTera2 cell line in response to conditioned medium from human astrocytes differing in Reelin, fibrillar Aβ, ApoE3, and conditioned medium from These findings suggest a comprehensive hypothesis for the pathogenesis of AD whereby the common factor in development of disease is antagonism of apoER2, likely to include agents that cannot promote the receptor's dimerization yet competitively inhibit those ligands that can cause dimerization. Show less

Limited targeted agents are approved for pediatric sarcomas. Tyrosine kinase (TK) inhibitors have shown clinical efficacy in some, but not all, young sarcoma patients. A major obstacle preventing further advances and clinical implementation is the lack of predictive response biomarkers to guide TK-targeted treatments. TK-activating fusions or mutations are rare in these patients. RNA overexpression of TKs is a frequent feature. The unresolved question is when upregulated TK expression is associated with kinase activation and signaling dependence. We explored the TK molecular landscape of 107 sarcoma patients from the ZERO Childhood Cancer precision medicine program (ZERO) using whole genomic and transcriptomic sequencing. Phosphoproteomic analyses of tyrosine phosphorylation (pY) and functional in vitro and in vivo assays were performed in cell lines and patient-derived xenografts (PDXs). Our analysis shows that although novel genomic driver lesions are rare, when present they are therapeutically actionable as exemplified by a novel LSM1-FGFR1 fusion identified in an osteosarcoma patient. We further show that in certain contexts, TK RNA expression can indicate TK pathway activity and predict TK-inhibitor sensitivity. We highlight the utility of FGFR-inhibitors in PAX3-FOXO1 fusion-positive rhabdomyosarcomas (FP-RMS) characterized by high FGFR4 and FGF8 RNA expression levels, and FGFR4 activation (FGFR4_pY). We demonstrate marked tumor growth inhibition in all FP-RMS PDXs treated with single agent FGF401 (FGFR4-specific inhibitor) and single agent lenvatinib (multi-kinase FGFR-inhibitor), and report a clinical response to lenvatinib in a relapsed metastatic FP-RMS patient. Altogether, we identified new sarcoma patients who may benefit from FGFR-inhibitors, most notably FP-rhabdomyosarcoma via FGFR4/FGF8 co-expression. Show less

One feature of high-fat diet-induced neurodegeneration in the hypothalamus is an increased level of palmitate, which is associated with endoplasmic reticulum (ER) stress, loss of CoxIV, mitochondrial fragmentation, and decreased abundance of MC4R. To determine whether antidiabetic drugs protect against ER and/or mitochondrial dysfunction by lipid stress, hypothalamic neurons derived from pre-adult mice and neuronal Neuro2A cells were exposed to elevated palmitate. In the hypothalamic neurons, palmitate exposure increased expression of ER resident proteins, including that of SERCA2, indicating ER stress. Liraglutide reverted such altered ER proteostasis, while metformin only normalized SERCA2 expression. In Neuro2A cells liraglutide, but not metformin, also blunted dilation of the ER induced by palmitate treatment, and enhanced abundance and expression of MC4R at the cell surface. Thus, liraglutide counteracts, more effectively than metformin, altered ER proteostasis, morphology, and folding capacity in neurons exposed to fat. In palmitate-treated hypothalamic neurons, mitochondrial fragmentation took place together with loss of CoxIV and decreased mitochondrial membrane potential (MMP). Metformin, but not liraglutide, reverted mitochondrial fragmentation, and both liraglutide and metformin did not protect against either loss of CoxIV abundance or MMP. Thus, ER recovery from lipid stress can take place in hypothalamic neurons in the absence of recovered mitochondrial homeostasis. Show less