PP-1β and PP-2Aα modulate cAMP response element-binding protein (CREB) functions in aging control and stress response through de-regulation of αB-crystallin gene and p300-p53 signaling axis

Circadian gene signatures in the progression of obesity based on machine learning and Mendelian randomization analysis

Objective

Obesity, a global health concern, is associated with a spectrum of chronic diseases and cancers. Our research sheds light on the regulatory role of circadian genes in obesity progression, providing insight into the immune landscape of obese patients, and introducing new avenues for therapeutic interventions.

Methods

Expression files of multiple datasets were retrieved from the GEO database. By 80 machine-learning algorithm combinations and Mendelian randomization analysis, we discovered the key circadian genes contributing to and protecting against obesity. Subsequently, an immune infiltration analysis was conducted to examine the alterations in immune cell types and their abundance in the body and to investigate the relationships between circadian genes and immune cells. Furthermore, we delved into the molecular mechanisms of key genes implicated in obesity.

Results

Our study identified three key circadian genes (BHLHE40, PPP1CB, and CSNK1E) associated with obesity. BHLHE40 was found to promote obesity through various pathways, while PPP1CB and CSNK1E counteracted lipid metabolism disorders, and modulated cytokines, immune receptors, T cells, and monocytes.

Conclusion

In conclusion, the key circadian genes (BHLHE40, CSNK1E, and PPP1CB) may serve as novel biomarkers for understanding obesity pathogenesis and have significant correlations with infiltrating immune cells, thus providing potential new targets for obese prevention and treatment.

Swimming exercise reverses transcriptomic changes in aging mouse lens

BACKGROUND

The benefits of physical activity for the overall well-being of elderly individuals are well-established, the precise mechanisms through which exercise improves pathological changes in the aging lens have yet to be fully understood.

METHODS

3-month-old C57BL/6J mice comprised young sedentary (YS) group, while aging mice (18-month-old) were divided into aging sedentary (AS) group and aging exercising (AE) group. Mice in AE groups underwent sequential stages of swimming exercise. H&E staining was employed to observe alterations in lens morphology. RNA-seq analysis was utilized to examine transcriptomic changes. Furthermore, qPCR and immunohistochemistry were employed for validation of the results.

RESULTS

AE group showed alleviation of histopathological aging changes in AS group. By GSEA analysis of the transcriptomic changes, swimming exercise significantly downregulated approximately half of the pathways that underwent alterations upon aging, where notable improvements were 'calcium signaling pathway', 'neuroactive ligand receptor interaction' and 'cell adhesion molecules'. Furthermore, we revealed a total of 92 differentially expressed genes between the YS and AS groups, of which 10 genes were observed to be mitigated by swimming exercise. The result of qPCR was in consistent with the transcriptome data. We conducted immunohistochemical analysis on Ciart, which was of particular interest due to its dual association as a common aging gene and its significant responsiveness to exercise. The Protein-protein Interaction network of Ciart showed the involvement of the regulation of Rorb and Sptbn5 during the process.

CONCLUSION

The known benefits of exercise could extend to the aging lens and support further investigation into the specific roles of Ciart-related pathways in aging lens.

High hydrostatic pressure participates in atrial fibrosis through the p300/p53/Smad3 pathway

As an independent risk factor of atrial fibrillation (AF), hypertension (HTN) can induce atrial fibrosis through cyclic stretch and hydrostatic pressure. The mechanism by which high hydrostatic pressure promotes atrial fibrosis is unclear yet. p300 and p53/Smad3 play important roles in the process of atrial fibrosis. This study investigated whether high hydrostatic pressure promotes atrial fibrosis by activating the p300/p53/Smad3 pathway. Biochemical experiments were used to study the expression of p300/p53/Smad3 pathway in left atrial appendage (LAA) tissues of patients with sinus rhythm (SR), AF, AF + HTN, and C57/BL6 mice, hypertensive C57/BL6 mice and atrial fibroblasts of mice. To investigate the roles of p300 and p53 in the process of atrial fibrosis, p300 and p53 in mice atrial fibroblasts were knocked in or knocked down, respectively. The expression of p300/p53/Smad3 and fibrotic factors was higher in patients with AF and AF + HTN than those with SR only. The expressions of p300/p53/Smad3 and fibrotic factors increased in hypertensive mice. Curcumin (Cur) and knocking down of p300 reversed the expressions of these factors. 40 mmHg hydrostatic pressure/overexpression of p300 upregulated the expressions of p300/p53/Smad3 and fibrotic factors in mice LAA fibroblasts. While Cur or knocking down p300 reversed these changes. Knocking down/overexpression of p53, the expressions of p53/Smad3 and fibrotic factors also decreased/increased, correspondingly. High hydrostatic pressure promotes atrial fibrosis by activating the p300/p53/Smad3 pathway, which further increases the susceptibility to AF.

SUMO1-regulated DBC1 promotes p53-dependent stress-induced apoptosis of lens epithelial cells

Deleted in breast cancer 1 (DBC1) was initially identified from a homozygously deleted region in human chromosome 8p21. It has been well established that DBC1 plays a dual role during cancer development. Depending on the physiological context, it can promote or inhibit tumorigenesis. Whether it plays a role in lens pathogenesis remains elusive. In the present study, we demonstrated that DBC1 is highly expressed in lens epithelial cells from different vertebrates and in retina pigment epithelial cells as well. Moreover, DBC1 is SUMOylated through SUMO1 conjugation at K591 residue in human and mouse lens epithelial cells. The SUMOylated DBC1 is localized in the nucleus and plays an essential role in promoting stress-induced apoptosis. Silence of DBC1 attenuates oxidative stress-induced apoptosis. In contrast, overexpression of DBC1 enhances oxidative stress-induced apoptosis, and this process depends on p53. Mechanistically, DBC1 interacts with p53 to regulate its phosphorylation status at multiple sites and the SUMOylation of DBC1 enhances its interaction with p53. Together, our results identify that DBC1 is an important regulator mediating stress-induced apoptosis in lens, and thus participates in control of lens cataractogenesis.

HSP90β prevents aging-related cataract formation through regulation of the charged multivesicular body protein (CHMP4B) and p53

Cataract is a leading ocular disease causing global blindness. The mechanism of cataractogenesis has not been well defined. Here, we demonstrate that the heat shock protein 90β (HSP90β) plays a fundamental role in suppressing cataractogenesis. HSP90β is the most dominant HSP in normal lens, and its constitutive high level of expression is largely derived from regulation by Sp1 family transcription factors. More importantly, HSP90β is significantly down-regulated in human cataract patients and in aging mouse lenses, whereas HSP90β silencing in zebrafish causes cataractogenesis, which can only be rescued by itself but not other HSP90 genes. Mechanistically, HSP90β can directly interact with CHMP4B, a newly-found client protein involved in control of cytokinesis. HSP90β silencing causes upregulation of CHMP4B and another client protein, the tumor suppressor p53. CHMP4B upregulation or overexpression induces excessive division of lens epithelial cells without proper differentiation. As a result, these cells were triggered to undergo apoptosis due to activation of the p53/Bak-Bim pathway, leading to cataractogenesis and microphthalmia. Silence of both HSP90β and CHMP4B restored normal phenotype of zebrafish eye. Together, our results reveal that HSP90β is a critical inhibitor of cataractogenesis through negative regulation of CHMP4B and the p53-Bak/Bim pathway.

Mitotic defects lead to unreduced sperm formation in cdk1-/- mutants

Unreduced gametes, that are important for species evolution and agricultural development, are generally believed to be formed by meiotic defects. However, we found that male diploid loach (Misgurnus anguillicaudatus) could produce not only haploid sperms, but also unreduced sperms, after cyclin-dependent kinase 1 gene (cdk1, one of the most important kinases in regulating cell mitosis) deletion. Observations on synaptonemal complexes of spermatocyte in prophase of meiosis and spermatogonia suggested that the number of chromosomes in some spermatogonia of cdk1^-/- loach doubled, leading to unreduced diploid sperm production. Then, transcriptome analysis revealed aberrant expressions of some cell cycle-related genes (such as ppp1c and gadd45) in spermatogonia of cdk1^-/- loach relative to wild-type loach. An in vitro and in vivo experiment further validated that Cdk1 deletion in diploid loach resulted in mitotic defects, leading to unreduced diploid sperm formation. In addition, we found that cdk1^-/- zebrafish could also produce unreduced diploid sperms. This study provides important information on revealing the molecular mechanisms behind unreduced gamete formation through mitotic defects, and lays the foundation for a novel strategy for fish polyploidy creation by using cdk1 mutants to produce unreduced sperms, which can then be used to obtain polyploidy, proposed to benefit aquaculture.

CACYBP knockdown inhibits progression of prostate cancer via p53

PURPOSE

Prostate cancer (PC) is one of the most common malignant tumors of genitourinary system in men. CACYCLIN binding protein (CACYBP) is involved in the progression of a variety of cancers. The aim of this study was to explore the expression and functional role of CACYBP in PC.

METHODS

The expression of CACYBP in PC was evaluated by immunohistochemical (IHC) staining and qRT-PCR. Subsequently, we established lentivirus-mediated CACYBP knockdown in PC cell lines. The biological roles of CACYBP on proliferation, apoptosis, cycle distribution, migration and tumor formation of PC were investigated by Celigo cell counting assay, flow cytometry, transwell assay, wound-healing assay and mice xenograft models, respectively.

RESULTS

CACYBP was highly expressed in PC and was positively correlated with the pathological grade of PC patients. Knockdown of CACYBP inhibited proliferation, enhanced apoptosis, arrested cell cycle in G2 and suppressed migration of PC cell lines in vitro. In addition, CACYBP knockdown weakened the tumor growth of PC in vivo. Moreover, addition of p53 inhibitor could effectively alleviate the inhibitory effect of CACYBP knockdown on cell activity.

CONCLUSION

This study revealed that knockdown of CACYBP inhibited the proliferation, migration and tumorigenicity of PC, which may serve as a potential therapeutic target for the treatment of PC.

MAB21L1 promotes survival of lens epithelial cells through control of αB-crystallin and ATR/CHK1/p53 pathway

The male abnormal gene family 21 (mab21), was initially identified in C. elegans. Since its identification, studies from different groups have shown that it regulates development of ocular tissues, brain, heart and liver. However, its functional mechanism remains largely unknown. Here, we demonstrate that Mab21L1 promotes survival of lens epithelial cells. Mechanistically, Mab21L1 upregulates expression of αB-crystallin. Moreover, our results show that αB-crystallin prevents stress-induced phosphorylation of p53 at S-20 and S-37 through abrogating the activation of the upstream kinases, ATR and CHK1. As a result of suppressing p53 activity by αB-crystallin, Mab21L1 downregulates expression of Bak but upregulates Mcl-1 during stress insult. Taken together, our results demonstrate that Mab21L1 promotes survival of lens epithelial cells through upregulation of αB-crystallin to suppress ATR/CHK1/p53 pathway.

PP-1β and PP-2Aα modulate cAMP response element-binding protein (CREB) functions in aging control and stress response through de-regulation of αB-crystallin gene and p300-p53 signaling axis

The function of the transcription factor, cAMP response element‐binding protein (CREB), is activated through S133 phosphorylation by PKA and others. Regarding its inactivation, it is not well defined. cAMP response element‐binding protein plays an essential role in promoting cell proliferation, neuronal survival and the synaptic plasticity associated with long‐term memory. Our recent studies have shown that CREB is an important player in mediating stress response. Here, we have demonstrated that CREB regulates aging process through suppression of αB‐crystallin and activation of the p300‐p53‐Bak/Bax signaling axis. First, we determined that two specific protein phosphatases, PP‐1β and PP‐2Aα, can inactivate CREB through S133 dephosphorylation. Subsequently, we demonstrated that cells expressing the S133A‐CREB, a mutant mimicking constant dephosphorylation at S133, suppress CREB functions in aging control and stress response. Mechanistically, S133A‐CREB not only significantly suppresses CREB control of αB‐crystallin gene, but also represses CREB‐mediated activation of p53 acetylation and downstream Bak/Bax genes. cAMP response element‐binding protein suppression of αB‐crystallin and its activation of p53 acetylation are major molecular events observed in human cataractous lenses of different age groups. Together, our results demonstrate that PP‐1β and PP‐2Aα modulate CREB functions in aging control and stress response through de‐regulation of αB‐crystallin gene and p300‐p53‐Bax/Bak signaling axis, which regulates human cataractogenesis in the aging lens.