Combined Transcriptomic and Proteomic Analysis of Perk Toxicity Pathways

The Role of Ubiquitin-Proteasome System and Mitophagy in the Pathogenesis of Parkinson's Disease

Parkinson's disease (PD) is a common neurodegenerative disease that is mainly in middle-aged people and elderly people, and the pathogenesis of PD is complex and diverse. The ubiquitin-proteasome system (UPS) is a master regulator of neural development and the maintenance of brain structure and function. Dysfunction of components and substrates of this UPS has been linked to neurodegenerative diseases such as Parkinson's disease and Alzheimer's disease. Moreover, UPS can regulate α-synuclein misfolding and aggregation, mitophagy, neuroinflammation and oxidative stress to affect the development of PD. In the present study, we review the role of several related E3 ubiquitin ligases and deubiquitinating enzymes (DUBs) on the pathogenesis of PD such as Parkin, CHIP, USP8, etc. On this basis, we summarize the connections and differences of different E3 ubiquitin ligases in the pathogenesis, and elaborate on the regulatory progress of different DUBs on the pathogenesis of PD. Therefore, we can better understand their relationships and provide feasible and valuable therapeutic clues for UPS-related PD treatment research.

Blocking dPerk in the intestine suppresses neurodegeneration in a Drosophila model of Parkinson's disease

Parkinson's disease (PD) is characterised by selective death of dopaminergic (DA) neurons in the midbrain and motor function impairment. Gastrointestinal issues often precede motor deficits in PD, indicating that the gut-brain axis is involved in the pathogenesis of this disease. The features of PD include both mitochondrial dysfunction and activation of the unfolded protein response (UPR) in the endoplasmic reticulum (ER). PINK1 is a mitochondrial kinase involved in the recycling of defective mitochondria, and PINK1 mutations cause early-onset PD. Like PD patients, pink1 mutant Drosophila show degeneration of DA neurons and intestinal dysfunction. These mutant flies also lack vital proteins due to sustained activation of the kinase R-like endoplasmic reticulum kinase (dPerk), a kinase that induces the UPR. Here, we investigated the role of dPerk in intestinal dysfunction. We showed that intestinal expression of dPerk impairs mitochondrial function, induces cell death, and decreases lifespan. We found that suppressing dPerk in the intestine of pink1-mutant flies rescues intestinal cell death and is neuroprotective. We conclude that in a fly model of PD, blocking gut-brain transmission of UPR-mediated toxicity, is neuroprotective.

The transcription factor ATF4 mediates endoplasmic reticulum stress-related podocyte injury and slit diaphragm defects

Mutations in OSGEP and four other genes that encode subunits of the KEOPS complex cause Galloway-Mowat syndrome, a severe, inherited kidney-neurological disease. The complex catalyzes an essential posttranscriptional modification of tRNA and its loss of function induces endoplasmic reticulum (ER) stress. Here, using Drosophila melanogaster garland nephrocytes and cultured human podocytes, we aimed to elucidate the molecular pathogenic mechanisms of KEOPS-related glomerular disease and to test pharmacological inhibition of ER stress-related signaling as a therapeutic principle. We found that ATF4, an ER stress-mediating transcription factor, or its fly orthologue Crc, were upregulated in both fly nephrocytes and human podocytes. Knockdown of Tcs3, a fly orthologue of OSGEP, caused slit diaphragm defects, recapitulating the human kidney phenotype. OSGEP cDNA with mutations found in patients lacked the capacity for rescue. Genetic interaction studies in Tcs3-deficient nephrocytes revealed that Crc mediates not only cell injury, but surprisingly also slit diaphragm defects, and that genetic or pharmacological inhibition of Crc activation attenuates both phenotypes. These findings are conserved in human podocytes where ATF4 inhibition improved the viability of podocytes with OSGEP knockdown, with chemically induced ER stress, and where ATF4 target genes and pro-apoptotic gene clusters are upregulated upon OSGEP knockdown. Thus, our data identify ATF4-mediated signaling as a molecular link among ER stress, slit diaphragm defects, and podocyte injury, and our data suggest that modulation of ATF4 signaling may be a potential therapeutic target for certain podocyte diseases.

Study on the molecular mechanism of nightshade in the treatment of colon cancer

The present study attempts to explore the effective components, action targets, and potential mechanism of nightshade for colon cancer treatment. The relationship network diagram of 'traditional Chinese medicine - component - target - disease' was firstly constructed by employing network pharmacology. Experiments were conducted in vivo and in vitro to verify the influence of quercetin, the core effective component of nightshade, on colon cancer. Meanwhile, the regulatory effects of quercetin on core targets and main signaling pathways were determined. Based on the network diagram of 'traditional Chinese medicine - component - target - disease' and KEGG analysis, quercetin might exhibit certain effects on colon cancer treatment by regulating the biological behavior of core targets related to cell apoptosis in tumors including PIK3R1, PIK3CA, Akt1, and Akt2. Furthermore, quercetin has been demonstrated in vitro experiments to suppress the proliferation and migration of colon cancer cells whereas promote their apoptosis in a dose-dependent fashion. In vivo experiments indicate that quercetin had an antitumor effect on human colon cancer SW480 cells in nude mice bearing tumors. Furthermore, PIK3CA could bind to quercetin directly, which is validated by immunocoprecipitation. Therefore, the activation of PI3K/AKT phosphorylation was inhibited by quercetin and moreover the expressions of apoptotic proteins caspase-3 and Bcl2-Associated X protein (BAX) were up-regulated. In conclusion, the potential mechanism of nightshade lies in the activation of the PI3K/AKT signaling pathway inhibited by quercetin, thus promoting apoptosis of colon cancer cells for colon cancer treatment.