The polyextremophile Natranaerobius thermophilus adopts a dual adaptive strategy to long-term salinity stress, simultaneously accumulating compatible solutes and K. Appl Environ Microbiol 2024:e0014524. [PMID: 38578096 DOI: 10.1128/aem.00145-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

The bacterium Natranaerobius thermophilus is an extremely halophilic alkalithermophile that can thrive under conditions of high salinity (3.3-3.9 M Na+), alkaline pH (9.5), and elevated temperature (53°C). To understand the molecular mechanisms of salt adaptation in N. thermophilus, it is essential to investigate the protein, mRNA, and key metabolite levels on a molecular basis. Based on proteome profiling of N. thermophilus under 3.1, 3.7, and 4.3 M Na+ conditions compared to 2.5 M Na+ condition, we discovered that a hybrid strategy, combining the "compatible solute" and "salt-in" mechanisms, was utilized for osmotic adjustment dur ing the long-term salinity adaptation of N. thermophilus. The mRNA level of key proteins and the intracellular content of compatible solutes and K+ support this conclusion. Specifically, N. thermophilus employs the glycine betaine ABC transporters (Opu and ProU families), Na+/solute symporters (SSS family), and glutamate and proline synthesis pathways to adapt to high salinity. The intracellular content of compatible solutes, including glycine betaine, glutamate, and proline, increases with rising salinity levels in N. thermophilus. Additionally, the upregulation of Na+/ K+/ H+ transporters facilitates the maintenance of intracellular K+ concentration, ensuring cellular ion homeostasis under varying salinities. Furthermore, N. thermophilus exhibits cytoplasmic acidification in response to high Na+ concentrations. The median isoelectric points of the upregulated proteins decrease with increasing salinity. Amino acid metabolism, carbohydrate and energy metabolism, membrane transport, and bacterial chemotaxis activities contribute to the adaptability of N. thermophilus under high salt stress. This study provides new data that support further elucidating the complex adaptation mechanisms of N. thermophilus under multiple extremes.IMPORTANCEThis study represents the first report of simultaneous utilization of two salt adaptation mechanisms within the Clostridia class in response to long-term salinity stress.

Effects of DISC1 on Alzheimer's disease cell models assessed by iTRAQ proteomics analysis

Alzheimer’s disease (AD) is a form of neurodegenerative disease in the elderly with no cure at present. In a previous study, we found that the scaffold protein, disrupted in Schizophrenia 1 (DISC1) is down-regulated in the AD brains, and ectopic expression of DISC1 can delay the progression of AD by protecting synaptic plasticity and down-regulating BACE1. However, the underlying mechanisms remain not to be elucidated. In the present study, we compared the proteomes of normal and DISC1^high AD cells expressing the amyloid precursor protein (APP) using isobaric tag for relative and absolute quantitation (iTRAQ) and mass spectrometry (MS). The differentially expressed proteins (DEPs) were identified, and the protein–protein interaction (PPI) network was constructed to identify the interacting partners of DISC1. Based on the interaction scores, NDE1, GRM3, PTGER3 and KATNA1 were identified as functionally or physically related to DISC1, and may therefore regulate AD development. The DEPs were functionally annotated by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases with the DAVID software, and the Non-supervised Orthologous Groups (eggNOG) database was used to determine their evolutionary relationships. The DEPs were significantly enriched in microtubules and mitochondria-related pathways. Gene set enrichment analysis (GSEA) was performed to identify genes and pathways that are activated when DISC1 is overexpressed. Our findings provide novel insights into the regulatory mechanisms underlying DISC1 function in AD.

Helicobacter pylori Targets in AGS Human Gastric Adenocarcinoma: In Situ Proteomic Profiling and Systematic Analysis

BACKGROUND/AIM

Helicobacter pylori, a gram-negative bacterium, causes chronic stomach diseases in humans. Heat shock proteins (HSPs) are involved in cell integrity, cell growth, and gastric mucosa colonization by H. pylori. This study aimed to investigate HSP expression levels in H. pylori-infected gastric adenocarcinoma AGS cells.

MATERIALS AND METHODS

We determined protein expression levels using iTRAQ proteomics analysis. We analyzed the possible network interactions for H. pylori targets in AGS cells using the Ingenuity Pathway Analysis (IPA) software.

RESULTS

H. pylori-infected AGS cells potentially targeted EIF2 and BAG2 signaling pathways to regulate cell physiology. In addition, after 3, 6, and 12 h of infection, western blotting revealed significantly decreased HSP70 and HSP105 expression.

CONCLUSION

H. pylori decreases HSPs in AGS gastric adenocarcinoma cells, and this is associated with the regulation of EIF2 and BAG2 signaling pathways.

Comparative proteomic and transcriptomic analysis reveals high pH-induced expression signatures of Chinese shrimp Fenneropenaeus chinensis

pH has a great impact on the distribution, growth, behavior, and physiology in many aquatic animals. The comparison of proteomics between normal and high pH stress samples was successfully achieved using iTRAQ proteomic analysis to screen key response proteins and pathways. After high pH stress, 124 upregulated and 41 downregulated proteins were identified. The higher expression levels of proteins like citrate synthase, glutathione S-transferase, glutathione peroxidase, and cytochrome c oxidase are associated with oxidative stress and mitochondrial dysfunction. The upregulation of glucose-regulated protein 78 indicated that the endoplasmic reticulum stress is induced by high pH stress. There were significant upregulation expressions of V-type H⁺-ATPase, Na⁺, K⁺-ATPase, 14-3-3 protein, as well as ATP-binding cassette transmembrane transporters after high pH exposure, which indicating their important roles in response to high pH stress. The abundance of proteins involved in protein glycosylation, oxidative pentose phosphate pathway, protein export, and glutathione metabolism were found enriched in high pH group than in control group. Quantitative proteomic profiling and integrated analysis with transcriptomic data provide new insights into the mechanisms underlying the molecular response to high pH stress in Fenneropenaeus chinensis.

Aluminum induced physiological and proteomic responses in tea (Camellia sinensis) roots and leaves

Tea (Camellia sinensis (L.) O. Kuntze), is an aluminum (Al) hyperaccumulator and grows well in acid soils. Although Al-induced growth of tea plant has been studied, the proteomic profiles of tea plants in response to Al are unclear. In the present study, the proteomic profiles in tea roots and leaves under Al stress were investigated using iTRAQ proteomics approach. In total, 755 and 1059 differentially expressed proteins were identified in tea roots and leaves, respectively. KEGG enrichment analysis showed that the differentially expressed proteins in roots were mainly involved in 11 pathways whereas those from leaves were mainly involved in 9 pathways. Abundance of most protein functions in glycolytic metabolism were enhanced in tea roots, and proteins involved in photosynthesis were stimulated in tea leaves. The protein ferulate-5-hydroxylase (F5H) in lignin biosynthetic pathway was down-regulated in both roots and leaves. Furthermore, antioxidant enzymes (ascorbate peroxidase, catalase and glutathione S-transferase) and citrate synthesis were accumulated in tea roots in response to Al. The results indicated that active photosynthesis and glycolysis as well as increased activities of antioxidant enzymes can be considered as a possible reason for the stimulatory effects of Al on the growth of tea plants. Additionally, the down-regulation of F5H and the binding of Al and phenolic acids may reduce the accumulation of lignin.