Early divergent modulation of NLRP2′s and NLRP3′s inflammasome sensors vs. AIM2′s one by signals from Aβ·Calcium-sensing receptor complexes in human astrocytes

Article

作者: Dal Prà, Ilaria ; Chang, Shusen ; Yin, Meifang ; Gui, Li ; Chiarini, Anna ; Armato, Ubaldo

Alzheimer's disease (AD), the most prevalent human dementia, is driven by accruals of extracellular Aβ₄₂ senile patches and intracellular neurofibrillary tangles of hyperphosphorylated Tau (p-Tau) proteins. AD's concurrent neuroinflammation is prompted by innate immunity-related cytosolic protein oligomers named inflammasomes. Upon proper "first" (priming) and "second" (activating) signals, inflammasomes overproduce proinflammatory Interleukin (IL)-1β, and IL-18 while cleaving pyroptosis-promoting Gasdermin D's N-terminal fragments. Our earlier studies highlighted that in pure monocultures, exogenous Aβ_25-35-treated nonproliferating human cortical astrocytes (HCAs) made and released surpluses of endogenous Aβ₄₂-oligomers (-os) and p-Tau-os, just as alike-treated human cortical neurons did. Aβ_25-35-exposed HCAs also over-released NO, VEGFA, and IL-6. Aβ•CaSR (Aβ·Calcium-Sensing Receptor) complexes generated intracellular signals mediating all such neurotoxic effects since CaSR's negative allosteric modulators (aka NAMs or calcilytics, e.g., NPS2143) fully suppressed them. However, it had hitherto remained unexplored whether signals from Aβ·CaSR complexes also induced the early expression and/or activation of NOD-like 2 (NLRP2) and 3 (NLRP3) and of PYHIN absent in melanoma 2 (AIM2) inflammasomes in monocultured HCAs. To clarify this topic, we used in-situ-Proximity Ligation, qRT-PCR, double antibody arrays, immunoblots, and Caspase 1/4 enzymatic assays. Aβ·CaSR complexes quickly assembled on HCAs surface and issued intracellular signals activating Akt and JAK/STAT axes. In turn, the latter upregulated NLRP2 and NLRP3 PRRs (pattern recognition receptors) yet downregulated AIM2. These effects were specific, being significantly hindered by NPS2143 and inhibitors of PI3K (LY294002), AMPKα (Dorsomorphin), mTOR (Torin1), and JAK/TYK (Brepoticinib). A wide-spectrum inhibitor, Bay11-7082, intensified the Aβ·CaSR/Akt/JAK/STAT axis-driven opposite control of NLRP3's and AIM2's PRR proteins without affecting NLRP2 PRR upregulation. However, the said effects on the PRRs proteins vanished within 24-h. Moreover, Aβ·CaSR signals neither concurrently changed ASC, pro-IL-1β, and Gasdermin-D (holo- and fragments) protein levels and Caspases 1 and 4 enzymatic activities nor induced pyroptosis. Therefore, Aβ·CaSR cues acted as "first (priming) signals" temporarily increasing NLRP2 and NLRP3 PRRs expression without activating the corresponding inflammasomes. The neatly divergent modulation of NLRP3's vs. AIM2's PRR proteins by Aβ·CaSR cues and by Bay11-7082 suggests that, when bacterial or viral DNA fragments are absent, AIM2 might play "anti-inflammasomal" or other roles in HCAs. However, Bay11-7082's no effect on NLRP2 PRR overexpression also reveals that CaSR's downstream mechanisms controlling inflammasomes' sensors are quite complex in HCAs, and hence, given AD's impact on human health, well worth further studies.

2024-12-01·Cellular and Molecular Life Sciences

Truncated tau interferes with the autophagy and endolysosomal pathway and results in lipid accumulation

Article

作者: Guo, Tong ; Jimenez-Sanchez, Maria ; Noble, Wendy ; Hanger, Diane P ; Chennell, George ; Pollack, Saskia J ; Gomez-Suaga, Patricia ; Dakkak, Dina

AbstractThe autophagy-lysosomal pathway plays a critical role in the clearance of tau protein aggregates that deposit in the brain in tauopathies, and defects in this system are associated with disease pathogenesis. Here, we report that expression of Tau35, a tauopathy-associated carboxy-terminal fragment of tau, leads to lipid accumulation in cell lines and primary cortical neurons. Our findings suggest that this is likely due to a deleterious block of autophagic clearance and lysosomal degradative capacity by Tau35. Notably, upon induction of autophagy by Torin 1, Tau35 inhibited nuclear translocation of transcription factor EB (TFEB), a key regulator of lysosomal biogenesis. Both cell lines and primary cortical neurons expressing Tau35 also exhibited changes in endosomal protein expression. These findings implicate autophagic and endolysosomal dysfunction as key pathological mechanisms through which disease-associated tau fragments could lead to the development and progression of tauopathy.

2024-09-01·Journal of Thrombosis and Haemostasis

Aging-related alterations in mechanistic target of rapamycin signaling promote platelet hyperreactivity and thrombosis

Article

作者: Reddy, Ashok P ; Babur, Özgün ; Weyrich, Andrew S ; Wilmarth, Phillip A ; Denorme, Frederik ; Aslan, Joseph E ; Portier, Irina ; Rondina, Matthew T ; Kosaka, Yasuhiro ; Tolley, Neal D ; Campbell, Robert A ; Manne, Bhanu Kanth

BACKGROUNDAging is an independent risk factor for the development of cardiovascular, thrombotic, and other chronic diseases. However, mechanisms of platelet hyperactivation in aging remain poorly understood.OBJECTIVESHere, we examine whether and how aging alters intracellular signaling in platelets to support platelet hyperactivity and thrombosis.METHODSQuantitative mass spectrometry with tandem mass tag labeling systematically measured protein phosphorylation in platelets from healthy aged (>65 years) and young human (<45 years) subjects. The role of platelet mechanistic target of rapamycin (mTOR) in aging-induced platelet hyperreactivity was assessed using pharmacologic mTOR inhibition and a platelet-specific mTOR-deficient mouse model (mTOR^plt-/-).RESULTSQuantitative phosphoproteomics uncovered differential site-specific protein phosphorylation within mTOR, Rho GTPase, and MAPK pathways in platelets from aged donors. Western blot confirmed constitutive activation of the mTOR pathway in platelets from both aged humans and mice, which was associated with increased aggregation compared with that in young controls. Inhibition of mTOR with either Torin 1 in aged humans or genetic deletion in aged mice reversed platelet hyperreactivity. In a collagen-epinephrine pulmonary thrombosis model, aged wild-type (mTOR^plt+/+) mice succumbed significantly faster than young controls, while time to death of aged mTOR^plt-/- mice was similar to that of young mTOR^plt+/+ mice. Mechanistically, we noted increased Rac1 activation and levels of mitochondrial reactive oxygen species in resting platelets from aged mice, as well as increased p38 phosphorylation upstream of thromboxane generation following agonist stimulation.CONCLUSIONAging-related changes in mTOR phosphorylation enhance Rac1 and p38 activation to enhance thromboxane generation, platelet hyperactivity, and thrombosis.

100 项与 Torin1 相关的药物交易

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