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The [beta]-secretase [beta]-site APP cleaving enzyme (BACE1) is a central drug target for Alzheimer's disease. Clinically tested, BACE1-directed inhibitors also block the homologous protease BACE2. Yet little is known about physiological BACE2 substrates and functions in vivo. Here, we identify BACE2 as the protease shedding the lymphangiogenic vascular endothelial growth factor receptor 3 (VEGFR3). Inactivation of BACE2, but not BACE1, inhibited shedding of VEGFR3 from primary human lymphatic endothelial cells (LECs) and reduced release of the shed, soluble VEGFR3 (sVEGFR3) ectodomain into the blood of mice, nonhuman primates, and humans. Functionally, BACE2 inactivation increased full-length VEGFR3 and enhanced VEGFR3 signaling in LECs and also in vivo in zebrafish, where enhanced migration of LECs was observed. Thus, this study identifies BACE2 as a modulator of lymphangiogenic VEGFR3 signaling and demonstrates the utility of sVEGFR3 as a pharmacodynamic plasma marker for BACE2 activity in vivo, a prerequisite for developing BACE1- selective inhibitors for safer prevention of Alzheimer's disease., Introduction Alzheimer's disease (AD) is the most common neurodegenerative disorder. Effective therapeutic or preventive approaches for this deadly disease are lacking. A central drug target for AD is the transmembrane [...]

Interleukin-17 (IL-17)-secreting T cells of the T helper 17 ([T.sub.H]17) lineage play a pathogenic role in multiple inflammatory and autoimmune conditions and thus represent a highly attractive target for therapeutic intervention. We report that inhibition of acetyl-CoA carboxylase 1 (ACC1) restrains the formation of human and mouse [T.sub.H]17 cells and promotes the development of anti-inflammatory Foxp[3.sup.+] regulatory T ([T.sub.reg]) cells. We show that [T.sub.H]17 cells, but not [T.sub.reg] cells, depend on ACC1-mediated de novo fatty acid synthesis and the underlying glycolytic-lipogenic metabolic pathway for their development. Although [T.sub.H]17 cells use this pathway to produce phospholipids for cellular membranes, [T.sub.reg] cells readily take up exogenous fatty acids for this purpose. Notably, pharmacologic inhibition or T cell-specific deletion of ACC1 not only blocks de novo fatty acid synthesis but also interferes with the metabolic flux of glucose-derived carbon via glycolysis and the tricarboxylic acid cycle. In vivo, treatment with the ACC-specific inhibitor soraphen A or T cell-specific deletion of ACC1 in mice attenuates [T.sub.H]17 cell-mediated autoimmune disease. Our results indicate fundamental differences between [T.sub.H]17 cells and [T.sub.reg] cells regarding their dependency on ACC1-mediated de novo fatty acid synthesis, which might be exploited as a new strategy for metabolic immune modulation of [T.sub.H]17 cell-mediated inflammatory diseases., To develop from naive cells into distinct T cell lineages, activated T cells undergo a massive metabolic switch to cope with the demands of cell growth and multiple rounds of [...]

The severe‐acute‐respiratory‐syndrome‐coronavirus‐2 (SARS‐CoV‐2) is the causative agent of COVID‐19, but host cell factors contributing to COVID‐19 pathogenesis remain only partly understood. We identify the host metalloprotease ADAM17 as a facilitator of SARS‐CoV‐2 cell entry and the metalloprotease ADAM10 as a host factor required for lung cell syncytia formation, a hallmark of COVID‐19 pathology. ADAM10 and ADAM17, which are broadly expressed in the human lung, cleave the SARS‐CoV‐2 spike protein (S) in vitro, indicating that ADAM10 and ADAM17 contribute to the priming of S, an essential step for viral entry and cell fusion. ADAM protease‐targeted inhibitors severely impair lung cell infection by the SARS‐CoV‐2 variants of concern alpha, beta, delta, and omicron and also reduce SARS‐CoV‐2 infection of primary human lung cells in a TMPRSS2 protease‐independent manner. Our study establishes ADAM10 and ADAM17 as host cell factors for viral entry and syncytia formation and defines both proteases as potential targets for antiviral drug development. Synopsis: The metalloproteases ADAM10 and ADAM17 facilitate SARS‐CoV‐2 infection and lung cell fusion, thereby contributing to SARS‐CoV‐2 pathogenesis. ADAM17 promotes SARS‐CoV‐2 infection of human lung cells.ADAM10 mediates spike‐induced syncytia formation.Mechanistically, ADAMs act by proteolytic activation of the spike protein. [ABSTRACT FROM AUTHOR]

Secretases are a group of proteases that are major drug targets considered for the prevention and treatment of Alzheimer's disease (AD). Secretases do not only process the AD-linked neuronal amyloid precursor protein (APP) but also the triggering receptor expressed on myeloid cells 2 (TREM2), thereby controlling microglial functions. This review highlights selected recent discoveries for the α-secretases a disintegrin and metalloprotease 10 (ADAM10) and a disintegrin and metalloprotease 17 (ADAM17), the β-secretase β-site APP cleaving enzyme 1 (BACE1) and γ-secretase and their link to AD. New genetic evidence strengthens the role of α-secretases in AD through cleavage of APP and TREM2. Novel proteins were linked to AD, which control α- and β-secretase activity through transcriptional and post-translational mechanisms. Finally, new opportunities but also challenges are discussed for pharmacologically targeting β- and γ-secretase cleavage of APP and α-secretase cleavage of TREM2 with the aim to prevent or treat AD. • Secreted frizzled-related protein 1, reversion-inducing cysteine-rich protein with Kazal motifs, ataxin-1 and nuclear factor erythroid-derived 2-related factor 2 control a disintegrin and metalloprotease 10 and β-site amyloid precursor protein cleaving enzyme 1 activity and are linked to AD. • New familial Alzheimer Uppsala mutation shifts amyloid precursor protein cleavage from α-to β-secretase. • Structure and pharmacology studies support drug development of γ-secretase modulators. • Triggering receptor expressed on myeloid cells 2 -agonistic antibodies show potential for reducing brain amyloidosis in mice. [ABSTRACT FROM AUTHOR]

In the version of this article initially published online, the number 21.45, corresponding to the percentage of cells, was missing from the bottom right quadrant of the flow cytometry plot [...]

Lesch–Nyhan syndrome (LNS) is characterized by uric acid overproduction and severe neurobehavioral symptoms, such as recurrent self-mutilative behavior. To learn more about the pathophysiology of the disease, we quantified neurotransmitters and their metabolites in the cerebral hemisphere, cerebellum and the medulla oblongata of HPRT knockout mice, an animal model for LNS, in comparison to the corresponding wild-type. Our analyses included l -glutamate, 4-aminobutanoic acid (GABA), acetylcholine, serotonin, 5-hydroxyindoleacetic acid (5-HIAA), norepinephrine, l -normetanephrine, epinephrine and l -metanephrine and were conducted via high performance liquid chromatography (HPLC) coupled to tandem mass spectrometry (MS/MS). Among these neurotransmitter systems, we did not find any abnormalities in the HPRT knockout mouse brains. On one side, this might indicate that HPRT deficiency most severely affects dopamine signaling, while brain functioning based on other neurotransmitters is more or less spared. On the other hand, our findings may reflect a compensating mechanism for impaired purine salvage that protects the brain in HPRT-deficient mice but not in LNS patients. [ABSTRACT FROM AUTHOR]

Lesch–Nyhan syndrome (LNS) is an X-chromosomal disorder with congenital deficiency of the purine salvage enzyme hypoxanthine-guanine phosphoribosyltransferase (HPRT) as underlying defect. We determined the concentrations of dopamine, histamine and their metabolites in brains of HPRT knockout mice, which serve as an animal model for LNS, and compared the results to those obtained from wild-type controls. Analyses were performed by high performance liquid chromatography (HPLC)-coupled tandem mass spectrometry (MS/MS). Besides a decrease of dopamine and 3-methoxytyramine (3-MT) concentrations in the cerebral hemisphere, HPRT-deficient mice also exhibited significantly reduced 1-methylhistamine (1-MH) and 1-methylimidazole-4-acetic acid (1-MI4AA) concentrations in the brain hemisphere and medulla. Moreover, the amount of 1-MI4AA was significantly decreased in the cerebellum. Our findings show that neuronal perturbations caused by HPRT deficiency are not restricted to the dopamine system but also affect histaminergic neurotransmission. These new insights into the brain metabolism of an LNS mouse model may help to find new therapeutic strategies to improve the quality of life of LNS patients. [ABSTRACT FROM AUTHOR]

The β-secretase β-site APP cleaving enzyme (BACE1) is a central drug target for Alzheimer's disease. Clinically tested, BACE1-directed inhibitors also block the homologous protease BACE2. Yet little is known about physiological BACE2 substrates and functions in vivo. Here, we identify BACE2 as the protease shedding the lymphangiogenic vascular endothelial growth factor receptor 3 (VEGFR3). Inactivation of BACE2, but not BACE1, inhibited shedding of VEGFR3 from primary human lymphatic endothelial cells (LECs) and reduced release of the shed, soluble VEGFR3 (sVEGFR3) ectodomain into the blood of mice, nonhuman primates, and humans. Functionally, BACE2 inactivation increased full-length VEGFR3 and enhanced VEGFR3 signaling in LECs and also in vivo in zebrafish, where enhanced migration of LECs was observed. Thus, this study identifies BACE2 as a modulator of lymphangiogenic VEGFR3 signaling and demonstrates the utility of sVEGFR3 as a pharmacodynamic plasma marker for BACE2 activity in vivo, a prerequisite for developing BACE1-selective inhibitors for safer prevention of Alzheimer's disease. [ABSTRACT FROM AUTHOR]

The cyclic pyrimidine nucleotides cCMP and cUMP occur in mammalian cell lines. Recently, cCMP was also identified in mouse organs. Due to technical difficulties, it has not been possible to detect cUMP in organs or tissues yet. Here, we have generated a temporal profile of the occurrence of nucleoside 3′,5′-cyclic monophosphates during different developmental stages of embryogenesis and in different organs of the adult zebrafish Danio rerio . Cyclic nucleotides were quantified by high performance liquid chromatography quadrupole tandem mass spectrometry. The identity of cCMP and cUMP in the zebrafish was confirmed by high performance liquid chromatography quadrupole time-of-flight mass spectrometry. We show for the first time that cUMP can be detected during embryogenesis and in adult organs of this vertebrate model system. [ABSTRACT FROM AUTHOR]

Several findings support the concept that sensorimotor integration is disturbed in Parkinson's disease (PD) and in levodopa-induced dyskinesias. In this study, we explored the neuronal firing activity of excitatory pyramidal cells and inhibitory interneurons in the forelimb region of the primary somatosensory cortex (S1FL-Ctx), along with its interaction with oscillatory activity of the primary motor cortex (MCtx) in 6-hydroxydopamine lesioned hemiparkinsonian (HP) and levodopa-primed dyskinetic (HP-LID) rats as compared to controls under urethane (1.4 g/kg, i.p.) anesthesia. Further, gene expression patterns of distinct markers for inhibitory GABAergic neurons were analyzed in both cortical regions. While firing frequency and burst activity of S1FL-Ctx inhibitory interneurons were reduced in HP and HP-LID rats, measures of irregularity were enhanced in pyramidal cells. Further, enhanced coherence of distinct frequency bands of the theta/alpha, high-beta, and gamma frequency, together with enhanced synchronization of putative pyramidal cells and interneurons with MCtx oscillatory activity were observed. While GABA level was similar, gene expression levels of interneuron and GABAergic markers in S1FL-Ctx and MCtx of HP-LID rats differed to some extent. Our study shows that in a rat model of PD with dyskinesias, neuronal activity in putative interneurons was reduced, which was accompanied by high beta and gamma coherence between S1FL-Ctx and MCtx, together with changes in gene expression, indicating maladaptive neuroplasticity after long term levodopa treatment. [ABSTRACT FROM AUTHOR]