Search

Introduction: The study of the pathophysiology study of Alzheimer's disease (AD) has been hampered by lack animal models that recapitulate the major AD pathologies, including extracellular -amyloid (A) deposition, intracellular aggregation of microtubule associated protein tau (MAPT), inflammation and neurodegeneration. Methods: The humanized APPNL-G-F knock-in mouse line was crossed to the PS19 MAPTP301S, over-expression mouse line to create the dual APPNLG-F/PS19 MAPTP301S line. The resulting pathologies were characterized by immunochemical methods and PCR. Results: We now report on a double transgenic APPNL-G-F/PS19 MAPTP301S mouse that at 6 months of age exhibits robust A plaque accumulation, intense MAPT pathology, strong inflammation and extensive neurodegeneration. The presence of A pathology potentiated the other major pathologies, including MAPT pathology, inflammation and neurodegeneration. MAPT pathology neither changed levels of amyloid precursor protein nor potentiated A accumulation. Interestingly, study of immunofluorescence in cleared brains indicates that microglial inflammation was generally stronger in the hippocampus, dentate gyrus and entorhinal cortex, which are regions with predominant MAPT pathology. The APPNL-G-F/MAPTP301S mouse model also showed strong accumulation of N6-methyladenosine (m6A), which was recently shown to be elevated in the AD brain. m6A primarily accumulated in neuronal soma, but also co-localized with a subset of astrocytes and microglia. The accumulation of m6A corresponded with increases in METTL3 and decreases in ALKBH5, which are enzymes that add or remove m6A from mRNA, respectively. Discussion: Our understanding of the pathophysiology of Alzheimer's disease (AD) has been hampered by lack animal models that recapitulate the major AD pathologies, including extracellular -amyloid (A) deposition, intracellular aggregation of microtubule associated protein tau (MAPT), inflammation and neurodegeneration. The APPNL-G-F/MAPTP301S mouse recapitulates many features of AD pathology beginning at 6 months of aging, and thus represents a useful new mouse model for the field. [ABSTRACT FROM AUTHOR]

Circulating increases in branched chain amino acid (BCAA) levels have long been associated with type 2 diabetes and metabolic syndrome. Emerging data also suggest that BCAA catabolism may play a role in heart failure progression. It is hypothesized that decreased catabolism, rather than increased consumption of BCAAs, is responsible for these correlations. Branched chain ketoacid (BCKA) dehydrogenase (BCKDH) kinase (BCKDK) is a negative regulator of BCAA catabolism through its inhibitory phosphorylation of the BCKDH E1a subunit. Using the BCKDK inhibitor molecule BT2, we demonstrate here a reduction of BCAA, BCKA and tissue p-BCKDH levels concomitant with improved glucose tolerance and reduced insulin levels in diet-induced obese mice after only one day of treatment. To investigate the mechanisms underlying this protection, we assessed plasma biomarkers and tissue gene expression after fasting and re-feeding in glucose intolerant high fat diet-fed animals. Remarkably, BT2 treated animals demonstrated reduced plasma glucose levels after re-feed, which was accompanied by dramatic reductions in plasma insulin levels, reduced activation of Akt in peripheral tissues, and a failure to suppress plasma free fatty acids and lipolytic machinery in adipose tissue. RNAseq was performed in liver to assess changes in gene expression profiles, and while over 400 genes were differentially regulated in vehicle treated re-fed mice compared with vehicle treated fasted mice, there were no differentially regulated genes in BT2 re-fed animals compared with BT2 fasted animals. These data suggest that activation of BCAA catabolism with the BCKDK inhibitor BT2 impairs the systemic response to feeding. Disclosure: E. Bollinger: Employee; Self; Pfizer Inc. C.P. Siddall: Employee; Self; Pfizer Inc. Employee; Spouse/Partner; Vertex Pharmaceuticals. T. Greizer: None. J.L. Libera: None. G. Hariri: None. E.E. Pashos: Employee; Self; Pfizer Inc. A. Shipstone: None. A. Hadjipanayis: None. Z. Sun: None. G. Xing: None. M.F. Clasquin: Employee; Spouse/Partner; Merck & Co., Inc. Employee; Self; Pfizer Inc. B.B. Zhang: Employee; Spouse/Partner; Janssen Pharmaceuticals, Inc. Employee; Self; Pfizer Inc. Other Relationship; Self; Eli Lilly and Company. R.A. Miller: Employee; Self; Pfizer Inc. R. Roth Flach: Employee; Self; Pfizer Inc. [ABSTRACT FROM AUTHOR]

Introduction: The study of the pathophysiology study of Alzheimer's disease (AD) has been hampered by lack animal models that recapitulate the major AD pathologies, including extracellular -amyloid (A) deposition, intracellular aggregation of microtubule associated protein tau (MAPT), inflammation and neurodegeneration., Methods: The humanized APP NL-G-F knock-in mouse line was crossed to the PS19 MAPT P301S , over-expression mouse line to create the dual APPNL-G-F/PS19 MAPTP301S line. The resulting pathologies were characterized by immunochemical methods and PCR., Results: We now report on a double transgenic APP NL-G-F /PS19 MAPT P301S mouse that at 6 months of age exhibits robust A plaque accumulation, intense MAPT pathology, strong inflammation and extensive neurodegeneration. The presence of A pathology potentiated the other major pathologies, including MAPT pathology, inflammation and neurodegeneration. MAPT pathology neither changed levels of amyloid precursor protein nor potentiated A accumulation. Interestingly, study of immunofluorescence in cleared brains indicates that microglial inflammation was generally stronger in the hippocampus, dentate gyrus and entorhinal cortex, which are regions with predominant MAPT pathology. The APP NL-G-F /MAPT P301S mouse model also showed strong accumulation of N 6 -methyladenosine (m 6 A), which was recently shown to be elevated in the AD brain. m 6 A primarily accumulated in neuronal soma, but also co-localized with a subset of astrocytes and microglia. The accumulation of m 6 A corresponded with increases in METTL3 and decreases in ALKBH5, which are enzymes that add or remove m6A from mRNA, respectively., Discussion: Our understanding of the pathophysiology of Alzheimer's disease (AD) has been hampered by lack animal models that recapitulate the major AD pathologies, including extracellular -amyloid (A) deposition, intracellular aggregation of microtubule associated protein tau (MAPT), inflammation and neurodegeneration. The APP NL-G-F /MAPT P301S mouse recapitulates many features of AD pathology beginning at 6 months of aging, and thus represents a useful new mouse model for the field., Competing Interests: CK and BN are employed by LifeCanvas Technologies. BW is co-founder and Chief Scientific Officer for Aquinnah Pharmaceuticals Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Jiang, Roberts, Wong, Zhang, Webber, Libera, Wang, Kilci, Jenkins, Ortiz, Dorrian, Sun, Sun, Rashad, Kornbrek, Daley, Dedon, Nguyen, Xia, Saito, Saido and Wolozin.)