Phosphorylation of STAT3 at Tyr705 contributes to TFEB-mediated autophagy-lysosomal pathway dysfunction and leads to ischemic injury in rats.

We previously reported that permanent ischemia induces marked dysfunction of the autophagy-lysosomal pathway (ALP) in rats, which is possibly mediated by the transcription factor EB (TFEB). However, it is still unclear whether signal transducer and activator of transcription 3 (STAT3) is responsible for the TFEB-mediated dysfunction of ALP in ischemic stroke. In the present study, we used AAV-mediated genetic knockdown and pharmacological blockade of p-STAT3 to investigate the role of p-STAT3 in regulating TFEB-mediated ALP dysfunction in rats subjected to permanent middle cerebral occlusion (pMCAO). The results showed that the level of p-STAT3 (Tyr705) in the rat cortex increased at 24 h after pMCAO and subsequently led to lysosomal membrane permeabilization (LMP) and ALP dysfunction. These effects can be alleviated by inhibitors of p-STAT3 (Tyr705) or by STAT3 knockdown. Additionally, STAT3 knockdown significantly increased the nuclear translocation of TFEB and the transcription of TFEB-targeted genes. Notably, TFEB knockdown markedly reversed STAT3 knockdown-mediated improvement in ALP function after pMCAO. This is the first study to show that the contribution of p-STAT3 (Tyr705) to ALP dysfunction may be partly associated with its inhibitory effect on TFEB transcriptional activity, which further leads to ischemic injury in rats.

An artificial peptide inhibits autophagy through calcineurin-TFEB pathway.

We previously reported that a bioactive peptide (pep3) can potently inhibit the enzyme activity of purified calcineurin (CN). In this paper, we further demonstrate that transfected pep3 can strongly inhibit CN enzyme activity in HEK293 cells. Transcription factor EB (TFEB) plays an important role in the autophagy-lysosome pathway (ALP) as one of the substrates of CN, so we study the effect of pep3 on the CN-TFEB-ALP pathway. Pep3 can significantly inhibit the mRNA levels of the TFEB downstream genes and the expression of the autophagy-associated proteins, and autophagy flux in HEK293 cells. We also validated the inhibitory effect of pep3 on autophagy in mice. These findings may provide a new idea for discovering more CN inhibitors and autophagy inhibitory drugs.

Potential application of natural compounds in ischaemic stroke: Focusing on the mechanisms underlying "lysosomocentric" dysfunction of the autophagy-lysosomal pathway.

Ischaemic stroke (IS) is the second leading cause of death and a major cause of disability worldwide. Currently, the clinical management of IS still depends on restoring blood flow via pharmacological thrombolysis or mechanical thrombectomy, with accompanying disadvantages of narrow therapeutic time window and risk of haemorrhagic transformation. Thus, novel pathophysiological mechanisms and targeted therapeutic candidates are urgently needed. The autophagy-lysosomal pathway (ALP), as a dynamic cellular lysosome-based degradative process, has been comprehensively studied in recent decades, including its upstream regulatory mechanisms and its role in mediating neuronal fate after IS. Importantly, increasing evidence has shown that IS can lead to lysosomal dysfunction, such as lysosomal membrane permeabilization, impaired lysosomal acidity, lysosomal storage disorder, and dysfunctional lysosomal ion homeostasis, which are involved in the IS-mediated defects in ALP function. There is tightly regulated crosstalk between transcription factor EB (TFEB), mammalian target of rapamycin (mTOR) and lysosomal function, but their relationship remains to be systematically summarized. Notably, a growing body of evidence emphasizes the benefits of naturally derived compounds in the treatment of IS via modulation of ALP function. However, little is known about the roles of natural compounds as modulators of lysosomes in the treatment of IS. Therefore, in this context, we provide an overview of the current understanding of the mechanisms underlying IS-mediated ALP dysfunction, from a lysosomal perspective. We also provide an update on the effect of natural compounds on IS, according to their chemical structural types, in different experimental stroke models, cerebral regions and cell types, with a primary focus on lysosomes and autophagy initiation. This review aims to highlight the therapeutic potential of natural compounds that target lysosomal and ALP function for IS treatment.

Systematic analysis of the mechanism of Xiaochaihu decoction in hepatitis B treatment via network pharmacology and molecular docking.

Hepatitis B (HB) is a globally prevalent infectious disease caused by the HB virus. Xiaochaihu decoction (XCHD) is a classic herbal formula with a long history of clinical application in treating HB. Although the anti-HB activity of XCHD has been reported, systematic research on the exact mechanism of action is lacking. Here, a network pharmacology-based approach was used to predict the active components, important targets, and potential mechanism of XCHD in HB treatment. Investigation included drug-likeness evaluation; absorption, distribution, metabolism, and elimination (ADME) screening; protein-protein interaction (PPI) network construction and cluster analysis; Gene Ontology (GO) analysis; and Kyoto Encyclopedia of Genes and Genomes (KEGG) annotation. Molecular docking was adopted to investigate the interaction between important target proteins and active components. Eighty-seven active components of XCHD and 155 anti-HB targets were selected for further analysis. The GO enrichment and similarity analysis results indicated that XCHD might perform similar or the same GO functions. Glycyrrhizae Radix (GR), one of the seven XCHD herbs, likely exerts some unique GO functions such as the regulation of interleukin-12 production, positive regulation of interleukin-1 beta secretion, and regulation of the I-kappaB/NF-kappaB complex. The PPI network and KEGG pathway analysis results showed that XCHD affects HB mainly through modulating pathways related to viral infection, immunity, cancer, signal transduction, and metabolism. Additionally, molecular docking verified that the active compounds (quercetin, chrysin, and capsaicin) could bind with the key targets. This work systematically explored the anti-HB mechanism of XCHD and provides a novel perspective for future pharmacological research.