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1.
BMC Plant Biol ; 24(1): 513, 2024 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-38849759

RESUMO

BACKGROUND: The phosphorylation of the Light-Harvesting Complex of photosystem II (LHCII) driven by STATE TRANSITION 7 (STN7) kinase is a part of one of the crucial regulatory mechanisms of photosynthetic light reactions operating in fluctuating environmental conditions, light in particular. There are evidenced that STN7 can also be activated without light as well as in dark-chilling conditions. However, the biochemical mechanism standing behind this complex metabolic pathway has not been deciphered yet. RESULTS: In this work, we showed that dark-chilling induces light-independent LHCII phosphorylation in runner bean (Phaseolus coccineus L.). In dark-chilling conditions, we registered an increased reduction of the PQ pool which led to activation of STN7 kinase, subsequent LHCII phosphorylation, and possible LHCII relocation inside the thylakoid membrane. We also presented the formation of a complex composed of phosphorylated LHCII and photosystem I typically formed upon light-induced phosphorylation. Moreover, we indicated that the observed steps were preceded by the activation of the oxidative pentose phosphate pathway (OPPP) enzymes and starch accumulation. CONCLUSIONS: Our results suggest a direct connection between photosynthetic complexes reorganization and dark-chilling-induced activation of the thioredoxin system. The proposed possible pathway starts from the activation of OPPP enzymes and further NADPH-dependent thioredoxin reductase C (NTRC) activation. In the next steps, NTRC simultaneously activates ADP-glucose pyrophosphorylase and thylakoid membrane-located NAD(P)H dehydrogenase-like complex. These results in starch synthesis and electron transfer to the plastoquinone (PQ) pool, respectively. Reduced PQ pool activates STN7 kinase which phosphorylates LHCII. In this work, we present a new perspective on the mechanisms involving photosynthetic complexes while efficiently operating in the darkness. Although we describe the studied pathway in detail, taking into account also the time course of the following steps, the biological significance of this phenomenon remains puzzling.


Assuntos
Luz , Phaseolus , Phaseolus/fisiologia , Phaseolus/metabolismo , Phaseolus/enzimologia , Fosforilação , Tilacoides/metabolismo , Complexo de Proteína do Fotossistema I/metabolismo , Temperatura Baixa , Complexos de Proteínas Captadores de Luz/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , Proteínas de Plantas/metabolismo , Amido/metabolismo , Via de Pentose Fosfato/fisiologia , Ativação Enzimática , Fotossíntese/fisiologia , Estresse Fisiológico , Proteínas Serina-Treonina Quinases/metabolismo
2.
Chem Res Toxicol ; 37(2): 208-211, 2024 02 19.
Artigo em Inglês | MEDLINE | ID: mdl-38191130

RESUMO

The Cell Counting Kit-8 (CCK-8) cell viability assay, also known as WST-8, is widely recognized for its nontoxic nature, making it suitable for further studies on treated cells. This practice is commonly observed in the field of tissue engineering. While live/dead imaging may not readily reveal macroscopic differences, our investigation has uncovered significant intracellular metabolic changes. Notably, we observed substantial down-regulation of metabolites within the glycolysis and pentose phosphate pathways. These metabolic alterations predominantly affect energy metabolism and may potentially impact the cellular redox environment. In light of these findings, we strongly recommend that researchers exercise caution when using cells treated with CCK-8 in subsequent experiments.


Assuntos
Glicólise , Via de Pentose Fosfato , Via de Pentose Fosfato/fisiologia , Sobrevivência Celular , Glicólise/fisiologia , Metabolismo Energético , Metaboloma
3.
Front Biosci (Landmark Ed) ; 29(1): 27, 2024 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-38287804

RESUMO

BACKGROUND: The pentose phosphate pathway (PPP) is a critical metabolic pathway that generates NADPH and ribose-5-phosphate for nucleotide biosynthesis and redox homeostasis. In this study, we investigated a potential regulatory role for Krüppel-like factor 8 (KLF8) in the control of PPP in lung adenocarcinoma (LUAD) cells. METHODS: Based on a comprehensive set of experimental approaches, including cell culture, molecular techniques, and functional assays, we revealed a novel mechanism by which KLF8 promotes the activation of glucose-6-phosphate dehydrogenase (G6PD), a component enzyme in the PPP. RESULTS: Our findings demonstrate that KLF8 inhibits the acetylation of G6PD, leading to its increased enzymatic activity. Additionally, we observed that KLF8 activates the transcription of SIRT2, which has been implicated in regulating G6PD acetylation. These results highlight the interplay between KLF8, G6PD, and protein acetylation in the regulation of PPP in LUAD. CONCLUSIONS: Understanding the intricate molecular mechanisms underlying the metabolic reprogramming driven by KLF8 in lung cancer provides valuable insights into potential therapeutic strategies targeting the PPP. This study emphasizes the significance of KLF8 as a key modulator of metabolic pathways and indicates the potential of targeting the KLF8-G6PD axis for lung cancer treatment.


Assuntos
Adenocarcinoma de Pulmão , Neoplasias Pulmonares , Humanos , Via de Pentose Fosfato/fisiologia , Sirtuína 2/genética , Sirtuína 2/metabolismo , Adenocarcinoma de Pulmão/genética , Neoplasias Pulmonares/genética , Pulmão/metabolismo , Fatores de Transcrição Kruppel-Like/genética , Fatores de Transcrição Kruppel-Like/metabolismo
4.
Clinics ; 66(supl.1): 33-43, 2011. ilus, graf
Artigo em Inglês | LILACS | ID: lil-593147

RESUMO

Cellular energy metabolism is one of the main processes affected during the transition from normal to cancer cells, and it is a crucial determinant of cell proliferation or cell death. As a support for rapid proliferation, cancer cells choose to use glycolysis even in the presence of oxygen (Warburg effect) to fuel macromolecules for the synthesis of nucleotides, fatty acids, and amino acids for the accelerated mitosis, rather than fuel the tricarboxylic acid cycle and oxidative phosphorylation. Mitochondria biogenesis is also reprogrammed in cancer cells, and the destiny of those cells is determined by the balance between energy and macromolecule supplies, and the efficiency of buffering of the cumulative radical oxygen species. In glioblastoma, the most frequent and malignant adult brain tumor, a metabolic shift toward aerobic glycolysis is observed, with regulation by well known genes as integrants of oncogenic pathways such as phosphoinositide 3-kinase/protein kinase, MYC, and hypoxia regulated gene as hypoxia induced factor 1. The expression profile of a set of genes coding for glycolysis and the tricarboxylic acid cycle in glioblastoma cases confirms this metabolic switch. An understanding of how the main metabolic pathways are modified by cancer cells and the interactions between oncogenes and tumor suppressor genes with these pathways may enlighten new strategies in cancer therapy. In the present review, the main metabolic pathways are compared in normal and cancer cells, and key regulations by the main oncogenes and tumor suppressor genes are discussed. Potential therapeutic targets of the cancer energetic metabolism are enumerated, highlighting the astrocytomas, the most common brain cancer.


Assuntos
Humanos , Neoplasias Encefálicas , Glutaminase , Glutamina , Oncogenes/fisiologia , Neoplasias Encefálicas , Proliferação de Células , Transformação Celular Neoplásica , Ciclo do Ácido Cítrico/fisiologia , Glicólise/fisiologia , Via de Pentose Fosfato/fisiologia , Células-Tronco , Células-Tronco
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