SerpinA3N Regulates the Secretory Phenotype of Mouse Senescent Astrocytes Contributing to Neurodegeneration

Senescent astrocyte accumulation in the brain during normal aging is a driver of age-related neurodegenerative diseases such as Alzheimer's disease. However, the molecular events underlying astrocyte senescence in Alzheimer's disease are not fully understood. In this study, we demonstrated that senescent astrocytes display a secretory phenotype known as the senescence-associated secretory phenotype (SASP), which is associated with the upregulation of various proinflammatory factors and the downregulation of neurotrophic growth factors (eg, NGF and BDNF), resulting in a decrease in astrocyte-mediated neuroprotection and increased risk of neurodegeneration. We found that SerpinA3N is upregulated in senescent primary mouse astrocytes after serial passaging in vitro or by H2O2 treatment. Further exploration of the underlying mechanism revealed that SerpinA3N deficiency protects against senescent astrocyte-induced neurodegeneration by suppressing SASP-related factors and inducing neurotrophic growth factors. Brain tissues from Alzheimer's disease model mice possessed increased numbers of senescent astrocytes. Moreover, senescent astrocytes exhibited upregulated SerpinA3N expression in vitro and in vivo, confirming that our cell model recapitulated the in vivo pathology of these neurodegenerative diseases. Altogether, our study reveals a novel molecular strategy to regulate the secretory phenotype of senescent astrocytes and implies that SerpinA3N and its regulatory mechanisms may be potential targets for delaying brain aging and aging-related neurodegenerative diseases.

Unveiling the anti-senescence effects and senescence-associated secretory phenotype (SASP) inhibitory mechanisms of Scutellaria baicalensis Georgi in low glucose-induced astrocytes based on boolean network

BACKGROUND

Astrocytes senescence has been demonstrated in the aging brain and Alzheimer's disease (AD). Moreover, lower glucose metabolism has been confirmed in the early stage of AD. However, whether low glucose could induce astrocytes senescence remain ambiguous. Studies have shown that the ethanol extracts of Scutellaria baicalensis Georgi (SGE) exert neuroprotective and anti-aging effects, while whether SGE could delay astrocytes senescence was unclear.

PURPOSE

This study investigated the anti-senescence effect of SGE in low glucose-induced T98G cells and primary astrocytes, and explored the possible mechanisms based on boolean network.

METHODS

The neuroprotective effects of SGE in low glucose-induced T98G cells were evaluated by measurement of cell viability, LDH, ROS and ATP. The anti-senescence effects of SGE were investigated by detection of senescence-associated β-galactosidase (SA-β-Gal), senescence-associated secretory phenotype (SASP), cell cycle and senescence-related markers. The possible mechanisms of SGE in delaying astrocytes senescence were discovered through integrating transcriptomics with boolean network, and validation experiments were further performed.

RESULTS

Our results revealed that low glucose could induce astrocytes senescence, and SGE could delay astrocytes senescence by decreasing the staining rate of SA-β-gal, reducing secretions of SASP factors (IL-6, CXCL1, MMP-1), alleviating cell cycle arrest in G0/G1 phase, decreasing the formation of punctate DNA foci and down-regulating the expression of p16INK4A, p21 and γH2A.X. Transcriptomics and further verification results showed that SGE could markedly inhibit the mRNA expression levels of SASP factors (CXCL10, CXCL2, CCL2, IL-6, CXCR4, CCR7). Moreover, C-X-C motif chemokine 10 (CXCL10) was predicted to be the key SASP factor affecting the network stability by using boolean network. Further experiments validated that SGE could markedly reduce CXCL10 level, decrease the secretion of IL-6 and inhibit cell migration in CXCL10 induced primary astrocytes.

CONCLUSION

In summary, our research unmasks that the anti-senescence effects of SGE were highly correlated with the suppression of SASP secretions, and CXCL10 mediated the SASP inhibition effect of SGE in low glucose-induced astrocytes. Our study highlights that the delay of astrocytes senescence and the inhibition of SASP might be a new mechanism of SGE for alleviating neurodegenerative diseases such as AD.