Microglial cytokines poison neuronal autophagy via CCR5, a druggable target.

In the prodromal phase of neurodegenerative diseases, microglia switch to an activated state resulting in increased secretion of pro-inflammatory factors. We reported that C - C chemokine ligand 3 (CCL3), C - C chemokine ligand 4 (CCL4) and C - C chemokine ligand 5 (CCL5) contained in the secretome of activated microglia inhibit neuronal autophagy via a non-cell autonomous mechanism. These chemokines bind and activate neuronal C - C chemokine receptor type 5 (CCR5), which, in turn, promotes phosphoinositide 3-kinase (PI3K) - protein kinase B (PKB, or AKT) - mammalian target of rapamycin complex 1 (mTORC1) pathway activation, which inhibits autophagy, thus causing the accumulation of aggregate-prone proteins in the cytoplasm of neurons.

Microglial-to-neuronal CCR5 signaling regulates autophagy in neurodegeneration.

In neurodegenerative diseases, microglia switch to an activated state, which results in excessive secretion of pro-inflammatory factors. Our work aims to investigate how this paracrine signaling affects neuronal function. Here, we show that activated microglia mediate non-cell-autonomous inhibition of neuronal autophagy, a degradative pathway critical for the removal of toxic, aggregate-prone proteins accumulating in neurodegenerative diseases.

Vinexin contributes to autophagic decline in brain ageing across species.

Autophagic decline is considered a hallmark of ageing. The activity of this intracytoplasmic degradation pathway decreases with age in many tissues and autophagy induction ameliorates ageing in many organisms, including mice. Autophagy is a critical protective pathway in neurons and ageing is the primary risk factor for common neurodegenerative diseases.

Transient siRNA-mediated protein knockdown in mouse followed by feeding/starving cycle and liver tissue analysis.

We present a protocol for in vivo siRNA-mediated knockdown of a gene of interest in mouse liver using systemic delivery via intravenous injection. We describe a step-by-step protocol for delivery of siRNA particles, with tips on how to optimize dosage. We detail steps for feeding/starving cycles as well as for liver tissue isolation, followed by gene expression analysis, measured at the mRNA and protein levels.

mTORC2 Assembly Is Regulated by USP9X-Mediated Deubiquitination of RICTOR.

The mechanistic target of rapamycin complex 2 (mTORC2) controls cell metabolism and survival in response to environmental inputs. Dysregulation of mTORC2 signaling has been linked to diverse human diseases, including cancer and metabolic disorders, highlighting the importance of a tightly controlled mTORC2. While mTORC2 assembly is a critical determinant of its activity, the factors regulating this event are not well understood, and it is unclear whether this process is regulated by growth factors.

LC3-positive structures are prominent in autophagy-deficient cells.

Autophagy is an evolutionarily conserved process across eukaryotes that degrades cargoes like aggregate-prone proteins, pathogens, damaged organelles and macromolecules via delivery to lysosomes. The process involves the formation of double-membraned autophagosomes that engulf the cargoes destined for degradation, sometimes with the help of autophagy receptors like p62, which are themselves autophagy substrates. LC3-II, a standard marker for autophagosomes, is generated by the conjugation of cytosolic LC3-I to phosphatidylethanolamine (PE) on the surface of nascent autophagosomes.

Author Correction: Felodipine induces autophagy in mouse brains with pharmacokinetics amenable to repurposing.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Felodipine induces autophagy in mouse brains with pharmacokinetics amenable to repurposing.

Neurodegenerative diseases like Alzheimer's disease, Parkinson's disease and Huntington's disease manifest with the neuronal accumulation of toxic proteins. Since autophagy upregulation enhances the clearance of such proteins and ameliorates their toxicities in animal models, we and others have sought to re-position/re-profile existing compounds used in humans to identify those that may induce autophagy in the brain. A key challenge with this approach is to assess if any hits identified can induce neuronal autophagy at concentrations that would be seen in humans taking the drug for its conventional indication.

CCT complex restricts neuropathogenic protein aggregation via autophagy.

Aberrant protein aggregation is controlled by various chaperones, including CCT (chaperonin containing TCP-1)/TCP-1/TRiC. Mutated CCT4/5 subunits cause sensory neuropathy and CCT5 expression is decreased in Alzheimer's disease. Here, we show that CCT integrity is essential for autophagosome degradation in cells or Drosophila and this phenomenon is orchestrated by the actin cytoskeleton.

IGF-1 receptor antagonism inhibits autophagy.

Inhibition of the insulin/insulin-like growth factor signalling pathway increases lifespan and protects against neurodegeneration in model organisms, and has been considered as a potential therapeutic target. This pathway is upstream of mTORC1, a negative regulator of autophagy. Thus, we expected autophagy to be activated by insulin-like growth factor-1 (IGF-1) inhibition, which could account for many of its beneficial effects.

Lysosomal positioning coordinates cellular nutrient responses.

mTOR (mammalian target of rapamycin) signalling and macroautophagy (henceforth autophagy) regulate numerous pathological and physiological processes, including cellular responses to altered nutrient levels. However, the mechanisms regulating mTOR and autophagy remain incompletely understood. Lysosomes are dynamic intracellular organelles intimately involved both in the activation of mTOR complex 1 (mTORC1) signalling and in degrading autophagic substrates.

Regulation of mammalian autophagy in physiology and pathophysiology.

(Macro)autophagy is a bulk degradation process that mediates the clearance of long-lived proteins and organelles. Autophagy is initiated by double-membraned structures, which engulf portions of cytoplasm. The resulting autophagosomes ultimately fuse with lysosomes, where their contents are degraded.

Novel targets for Huntington's disease in an mTOR-independent autophagy pathway.

Autophagy is a major clearance route for intracellular aggregate-prone proteins causing diseases such as Huntington's disease. Autophagy induction with the mTOR inhibitor rapamycin accelerates clearance of these toxic substrates. As rapamycin has nontrivial side effects, we screened FDA-approved drugs to identify new autophagy-inducing pathways.