Blockage of glutamine-dependent anaplerosis affects mTORC1/2 activity and ultimately leads to cellular senescence-like response

Metabolic regulation of endothelial senescence

Endothelial cell (EC) senescence is increasingly recognized as a significant contributor to the development of vascular dysfunction and age-related disorders and diseases, including cancer and cardiovascular diseases (CVD). The regulation of cellular senescence is known to be influenced by cellular metabolism. While extensive research has been conducted on the metabolic regulation of senescence in other cells such as cancer cells and fibroblasts, our understanding of the metabolic regulation of EC senescence remains limited. The specific metabolic changes that drive EC senescence are yet to be fully elucidated. The objective of this review is to provide an overview of the intricate interplay between cellular metabolism and senescence, with a particular emphasis on recent advancements in understanding the metabolic changes preceding cellular senescence. I will summarize the current knowledge on the metabolic regulation of EC senescence, aiming to offer insights into the underlying mechanisms and future research directions.

Specific activation of hypoxia-inducible factor-2α by propionate metabolism via a β-oxidation-like pathway stimulates MUC2 production in intestinal goblet cells

Microbiota-derived short-chain fatty acids (SCFAs) are known to stimulate mucin expression in the intestine, which contributes to the gut mucosal immune responses, and the gut mucosal immune system extends to the brain and other organs through several axes. Hypoxia-inducible factors (HIFs), especially HIF-1α, are known to act as the master regulator of mucin expression, however, underlying mechanism of mucin expression during hypoxia by SCFAs remains unclear. In this study, we investigated the mechanism of MUC2 expression by propionate, an SCFA, in intestinal goblet cells. The real time oxygen consumption rate (OCR) and ATPase activity were measured to investigate the induction of hypoxia by propionate. Using 2-dimensional electrophoresis (2-DE), microarray analysis, and siRNA-induced gene silencing, we found that propionate is metabolized via a β-oxidation-like pathway instead of the vitamin B₁₂-dependent carboxylation pathway (also known as the methylmalonyl pathway). We verified the results by analyzing several intermediates in the pathway using LC-MS and GC-MS. Propionate metabolism via the β-oxidation-like pathway leads to the depletion of oxygen and thereby induces hypoxia. Analysis of HIFs revealed that HIF-2α is the primary HIF whose activation is induced by propionate metabolism in a hypoxic environment and that HIF-2α regulates the expression of MUC2. Thus, hypoxia induced during propionate metabolism via a β-oxidation-like pathway specifically activates HIF-2α, stimulating MUC2 production in LS 174 T goblet cells. Our findings show that propionate-induced selective HIF-2α stimulation contributes to intestinal mucosal defense.

Cellular aging beyond cellular senescence: Markers of senescence prior to cell cycle arrest in vitro and in vivo

The field of research on cellular senescence experienced a rapid expansion from being primarily focused on in vitro aspects of aging to the vast territories of animal and clinical research. Cellular senescence is defined by a set of markers, many of which are present and accumulate in a gradual manner prior to senescence induction or are found outside of the context of cellular senescence. These markers are now used to measure the impact of cellular senescence on aging and disease as well as outcomes of anti-senescence interventions, many of which are at the stage of clinical trials. It is thus of primary importance to discuss their specificity as well as their role in the establishment of senescence. Here, the presence and role of senescence markers are described in cells prior to cell cycle arrest, especially in the context of replicative aging and in vivo conditions. Specifically, this review article seeks to describe the process of "cellular aging": the progression of internal changes occurring in primary cells leading to the induction of cellular senescence and culminating in cell death. Phenotypic changes associated with aging prior to senescence induction will be characterized, as well as their effect on the induction of cell senescence and the final fate of cells reviewed. Using published datasets on assessments of senescence markers in vivo, it will be described how disparities between quantifications can be explained by the concept of cellular aging. Finally, throughout the article the applicational value of broadening cellular senescence paradigm will be discussed.

Neural signaling modulates metabolism of gastric cancer

Tumors comprise cancer cells and the associated stromal and immune/inflammatory cells, i.e., tumor microenvironment (TME). Here, we identify a metabolic signature of human and mouse model of gastric cancer and show that vagotomy in the mouse model reverses the metabolic reprogramming, reflected by metabolic switch from glutaminolysis to OXPHOS/glycolysis and normalization of the energy metabolism in cancer cells and TME. We next identify and validate SNAP25, mTOR, PDP1/α-KGDH, and glutaminolysis as drug targets and accordingly propose a therapeutic strategy to target the nerve-cancer metabolism. We demonstrate the efficacy of nerve-cancer metabolism therapy by intratumoral injection of BoNT-A (SNAP25 inhibitor) with systemic administration of RAD001 and CPI-613 but not cytotoxic drugs on overall survival in mice and show the feasibility in patients. These findings point to the importance of neural signaling in modulating the tumor metabolism and provide a rational basis for clinical translation of the potential strategy for gastric cancer.

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Metabolic reprogramming in gastric cancer cells and tumor microenvironment

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SNAP25, mTOR, PDP1/α-KGDH, and glutaminolysis as potential drug targets

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Combination of botulinum toxin type A, RAD001, and CPI-613 as a potential treatment