Lipid and glucose metabolism in senescence

The Intersection of cerebral cholesterol metabolism and Alzheimer's disease: Mechanisms and therapeutic prospects

Alzheimer's disease (AD) is a common neurodegenerative disease in the elderly, the exact pathogenesis of which remains incompletely understood, and effective preventive and therapeutic drugs are currently lacking. Cholesterol plays a vital role in cell membrane formation and neurotransmitter synthesis, and its abnormal metabolism is associated with the onset of AD. With the continuous advancement of imaging techniques and molecular biology methods, researchers can more accurately explore the relationship between cholesterol metabolism and AD. Elevated cholesterol levels may lead to vascular dysfunction, thereby affecting neuronal function. Additionally, abnormal cholesterol metabolism may affect the metabolism of β-amyloid protein, thereby promoting the onset of AD. Brain cholesterol levels are regulated by multiple factors. This review aims to deepen the understanding of the subtle relationship between cholesterol homeostasis and AD, and to introduce the latest advances in cholesterol-regulating AD treatment strategies, thereby inspiring readers to contemplate deeply on this complex relationship. Although there are still many unresolved important issues regarding the risk of brain cholesterol and AD, and some studies may have opposite conclusions, further research is needed to enrich our understanding. However, these findings are expected to deepen our understanding of the pathogenesis of AD and provide important insights for the future development of AD treatment strategies targeting brain cholesterol homeostasis.

Association between fatigue, peripheral serotonin, and L-carnitine in hypothyroidism and in chronic fatigue syndrome

Background

Fatigue of unknown origin is a hallmark symptom in chronic fatigue syndrome (CFS) and is also found in 20% of hypothyroidism patients despite appropriate levothyroxine treatment. Here, we suggest that in these disorders, peripheral serotonin levels are low, and elevating them to normal range with L-carnitine is accompanied with reduced fatigue.

Methods

We conducted a retrospective analysis of follow-up clinical data (CFS N=12; hypothyroidism with fatigue N=40) where serum serotonin and fatigue levels were compared before vs. after 7 weeks of oral L-carnitine supplementation.

Results

After L-carnitine, serotonin increased (8-fold in CFS, Sig. = 0.002, 6-fold in hypothyroidism, Sig. < 0.001) whereas fatigue decreased (2-fold in both CFS and hypothyroidism, Sig. = 0.002 for CFS, Sig. < 0.001 for hypothyroidism). There was a negative correlation between serotonin level and fatigue (for CFS, rho = -0.49 before and -0.67 after L-carnitine; for hypothyroidism, rho = -0.24 before and -0.83 after L-carnitine).

Conclusions

These findings suggest a new link between low peripheral serotonin, L-carnitine, and fatigue.

Senotherapeutics to Counteract Senescent Cells Are Prominent Topics in the Context of Anti-Ageing Strategies

Cellular senescence is implicated in ageing and associated with a broad spectrum of age-related diseases. Importantly, a cell can initiate the senescence program irrespective of the organism's age. Various stress signals, including those defined as ageing hallmarks and alterations leading to cancer development, oncogene activation, or loss of cancer-suppressive functions, can trigger cellular senescence. The primary outcome of these alterations is the activation of nuclear factor (NF)-κB, thereby inducing the senescence-associated secretory phenotype (SASP). Proinflammatory cytokines and chemokines, components of this phenotype, contribute to chronic systemic sterile inflammation, commonly referred to as inflamm-ageing. This inflammation is linked to age-related diseases (ARDs), frailty, and increased mortality in older individuals. Additionally, senescent cells (SCs) accumulate in multiple tissues with age and are believed to underlie the organism functional decline, as demonstrated by models. An escalating effort has been dedicated to identify senotherapeutics that selectively target SCs by inducing apoptosis; these drugs are termed senolytics. Concurrently, small molecules that suppress senescent phenotypes without causing cell death are known as senomorphics. Both natural and synthetic senotherapeutics, along with immunotherapies employing immune cell-mediated clearance of SCs, currently represent the most promising strategies to combat ageing and ARDs. Indeed, it is fascinating to observe that information regarding the immune reaction to SCs indicates that regulation by specific lymphocyte subsets, elevated in the oldest centenarians, plays a role in attaining extreme longevity. Regardless, the application of methods already utilized in cancer treatment, such as CAR cells and monoclonal antibodies, broadens the spectrum of potential approaches to be utilized.

Lactylation stabilizes DCBLD1 activating the pentose phosphate pathway to promote cervical cancer progression

BACKGROUND

Discoidin, CUB, and LCCL domain-containing type I (DCBLD1) is identified as an oncogene involved in multiple regulation of tumor progression, but specific mechanisms remain unclear in cervical cancer. Lactate-mediated lactylation modulates protein function. Whether DCBLD1 can be modified by lactylation and the function of DCBLD1 lactylation are unknown. Therefore, this study aims to investigate the lactylation of DCBLD1 and identify its specific lactylation sites. Herein, we elucidated the mechanism by which lactylation modification stabilizes the DCBLD1 protein. Furthermore, we investigated DCBLD1 overexpression activating pentose phosphate pathway (PPP) to promote the progression of cervical cancer.

METHODS

DCBLD1 expression was examined in human cervical cancer cells and adjacent non-tumorous tissues using quantitative reverse transcription-polymerase chain reaction, western blotting, and immunohistochemistry. In vitro and in vivo studies were conducted to investigate the impact of DCBLD1 on the progression of cervical cancer. Untargeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) metabolomics studies were used to characterize DCBLD1-induced metabolite alterations. Western blot, immunofuorescence and transmission electron microscopy were performed to detect DCBLD1 degradation of G6PD by activating autophagy. Chromatin immunoprecipitation, dual luciferase reporter assay for detecting the mechanism by which lactate increases DCBLD1 transcription. LC-MS/MS was employed to verify specific modification sites within the DCBLD1 protein.

RESULTS

We found that lactate increased DCBLD1 expression, activating the PPP to facilitate the proliferation and metastasis of cervical cancer cells. DCBLD1 primarily stimulated PPP by upregulating glucose-6-phosphate dehydrogenase (G6PD) expression and enzyme activity. The mechanism involved the increased enrichment of HIF-1α in the DCBLD1 promoter region, enhancing the DCBLD1 mRNA expression. Additionally, lactate-induced DCBLD1 lactylation stabilized DCBLD1 expression. We identified DCBLD1 as a lactylation substrate, with a predominant lactylation site at K172. DCBLD1 overexpression inhibited G6PD autophagic degradation, activating PPP to promote cervical cancer progression. In vivo, 6-An mediated inhibition of G6PD enzyme activity, inhibiting tumor proliferation.

CONCLUSIONS

Our findings revealed a novel post-translational modification type of DCBDL1, emphasizing the significance of lactylation-driven DCBDL1-mediated PPP in promoting the progression of cervical cancer.