Ubiquitin-mediated degradation at the Golgi apparatus

Genome-Wide Identification of ATL Gene Family in Wheat and Their Expression Analysis in Response to Salt Stress

Wheat (Triticum aestivum) is one of the most important cereal crops globally, with significant economic value. The Arabidopsis Tóxicos en Levadura (ATL) gene family, which comprises members of ubiquitin ligase enzymes (E3s), functions in substrate protein tagging during ubiquitin-mediated protein modification. Recent studies have demonstrated its involvement in stress responses. However, the ATL gene family in wheat remains poorly characterized. This study aimed to identify the members of the ATL gene family in wheat and investigate their roles under salt stress. We identified 334 TaATL genes in the wheat genome, all of which contain either RING-H2, RING U-box, or RAD18 superfamily domains, exhibiting a remarkably low proportion of intron-containing genes. The Ka/Ks (non-synonymous to synonymous substitution rate) analysis and cis-acting element analysis of the TaATL gene family indicate that its sequences are highly conserved and functionally constrained, suggesting that it may participate in abiotic stress responses through the ABA, MeJA, and MYB signaling pathways. Both RNA-seq analysis and RT-qPCR data demonstrated that the expression levels of the TaATL gene family were significantly upregulated under stress conditions, indicating their crucial roles in stress responses. This study demonstrates that the targeted regulation of stress-responsive signaling pathways mediated by superior TaATL gene family members can effectively enhance wheat salt tolerance, thereby providing a viable strategy for the development of high-yielding cultivars adapted to saline agricultural ecosystems.

GOLPH3 promotes calcium oxalate-induced renal injury and fibrosis through Golgi stress-mediated apoptosis and inflammatory responses

A common urological disorder, calcium oxalate (CaOx) stones are the most common form of kidney stones. Deposition of CaOx crystals leads to tubular damage, interstitial fibrosis, and chronic kidney disease. Understanding the intrinsic mechanisms of kidney stone formation is essential for the prevention of kidney stones and the development of new therapeutic agents. The Golgi apparatus is a key organelle in the secretory pathway of eukaryotic cells, which plays an important role in the sorting, modification, and transport of proteins within the cell, and has been reported to be involved in several diseases, including prostate tumors, gastrointestinal tumors, sepsis, and so on. GOLPH3 is also known as GPP34, GMx33, or MIDAS. It is a glycoprotein that regulates traffic between the trans-Golgi network and the cell membrane. However, its role in renal injury caused by CaOx crystal deposition is still unclear. Results from immunohistochemistry, qRT-PCR, western blot, and public database single nucleotide RNA-seq showed that GOLPH3 was significantly upregulated in kidney stone patients and animal kidneys. Significant inhibition of Golgi stress, apoptosis, and renal fibrosis by GOLPH3 inhibition with siRNA in CaOx-stimulated HK-2 cells. The PI3K\AKT\mTOR signaling pathway was inhibited by GOLPH3 knockdown, which may be associated with reduced inflammatory response and apoptosis, as well as restoration of Golgi morphology and function. In conclusion, GOLPH3 plays a critical role in CaOx-induced kidney injury by promoting Golgi stress and increasing inflammatory responses, apoptosis, and renal fibrosis, suggesting that GOLPH3 is a potential therapeutic target for kidney stones.

The Dsc ubiquitin ligase complex identifies transmembrane degrons to degrade orphaned proteins at the Golgi

The Golgi apparatus is essential for protein sorting, yet its quality control mechanisms are poorly understood. Here we show that the Dsc ubiquitin ligase complex uses its rhomboid pseudo-protease subunit, Dsc2, to assess the hydrophobic length of α-helical transmembrane domains (TMDs) at the Golgi. Thereby the Dsc complex likely interacts with orphaned ER and Golgi proteins that have shorter TMDs and ubiquitinates them for targeted degradation. Some Dsc substrates will be extracted by Cdc48 for endosome and Golgi associated proteasomal degradation (EGAD), while others will undergo ESCRT dependent vacuolar degradation. Some substrates are degraded by both, EGAD- or ESCRT pathways. The accumulation of Dsc substrates entails a specific increase in glycerophospholipids with shorter and asymmetric fatty acyl chains. Hence, the Dsc complex mediates the selective degradation of orphaned proteins at the sorting center of cells, which prevents their spreading across other organelles and thereby preserves cellular membrane protein and lipid composition.

Biochemical profiling of the protein encoded by grass carp reovirus genotype II

In this study, we obtained the whole genome sequence of GCRV-DY197 and investigated the localization, post-translational modifications, and host interactions of the 11 viral proteins encoded by GCRV-DY197 in grass carp ovary (GCO) cells. The whole genome sequence is 24,704 kb and contains 11 segments (S1-S11). Subcellular localization showed that the VP1, VP2, VP3, VP5, VP56, and VP35 proteins were localized in both cytoplasm and nucleus, whereas the NS79, VP4, VP41, VP6, and NS38 proteins were localized in the cytoplasm. The NS79 and NS38 proteins were phosphorylated, and the ubiquitination modification sites were identified in VP41 and NS38. An interaction network containing 9 viral proteins and 140 host proteins was also constructed. These results offer a theoretical basis for an in-depth understanding of the biochemical characteristics and pathogenic mechanism of GCRV-II.

Targeting the Ubiquitin-Proteasome System and Recent Advances in Cancer Therapy

Ubiquitination is a reversible post-translational modification based on the chemical addition of ubiquitin to proteins with regulatory effects on various signaling pathways. Ubiquitination can alter the molecular functions of tagged substrates with respect to protein turnover, biological activity, subcellular localization or protein-protein interaction. As a result, a wide variety of cellular processes are under ubiquitination-mediated control, contributing to the maintenance of cellular homeostasis. It follows that the dysregulation of ubiquitination reactions plays a relevant role in the pathogenic states of human diseases such as neurodegenerative diseases, immune-related pathologies and cancer. In recent decades, the enzymes of the ubiquitin-proteasome system (UPS), including E3 ubiquitin ligases and deubiquitinases (DUBs), have attracted attention as novel druggable targets for the development of new anticancer therapeutic approaches. This perspective article summarizes the peculiarities shared by the enzymes involved in the ubiquitination reaction which, when deregulated, can lead to tumorigenesis. Accordingly, an overview of the main pharmacological interventions based on targeting the UPS that are in clinical use or still in clinical trials is provided, also highlighting the limitations of the therapeutic efficacy of these approaches. Therefore, various attempts to circumvent drug resistance and side effects as well as UPS-related emerging technologies in anticancer therapeutics are discussed.