MDM2 accelerated renal senescence via ubiquitination and degradation of HDAC1.

Senescence, an intricate and inevitable biological process, characterized by the gradual loss of homeostasis and declining organ functions. The pathological features of cellular senescence, including cell cycle arrest, metabolic disruptions, and the emergence of senescence-associated secretory phenotypes (SASP), collectively contribute to the intricate and multifaceted nature of senescence. Beyond its classical interaction with p53, murine double minute gene 2 (MDM2), traditionally known as an E3 ubiquitin ligase involved in protein degradation, plays a pivotal role in cellular processes governing senescence. Histone deacetylase (HDAC), a class of histone deacetylases mainly expressed in the nucleus, has emerged as a critical contributor to renal tissues senescence. In this study we investigated the interplay between MDM2 and HDAC1 in renal senescence. We established a natural aging model in mice over a 2-year period that was verified by SA-ß-GAL staining and increased expression of senescence-associated markers such as p21, p16, and TNF-α in the kidneys. Furthermore, we showed that the expression of MDM2 was markedly increased, while HDAC1 expression underwent downregulation during renal senescence. This phenomenon was confirmed in H2O2-stimulated HK2 cells in vitro. Knockout of renal tubular MDM2 alleviated renal senescence in aged mice and in H2O2-stimulated HK2 cells. Moreover, we demonstrated that MDM2 promoted renal senescence by orchestrating the ubiquitination and subsequent degradation of HDAC1. These mechanisms synergistically accelerate the aging process in renal tissues, highlighting the intricate interplay between MDM2 and HDAC1, underpinning the age-related organ function decline.

Aberrant expression of COL4A1 in age-related cataract and its effect on cell proliferation, apoptosis and gene expression changes.

AIM: To evaluate the regulation of the aberrant expression of collagen type IV alpha 1 chain (COL4A1) in the development of age-related cataract (ARC). METHODS: Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and Western blot analysis were employed to evaluate the expression of COL4A1 in ARC patients and healthy controls. The proliferation, apoptosis, cell cycle and epithelial-mesenchymal transition (EMT) of human lens epithelial cell (HLE-B3) were further analyzed under the condition of COL4A1 gene silence. Alteration of gene expression at mRNA level after knockdown COL4A1 were also evaluated by qRT-PCR on HLE-B3 cells. RESULTS: The aberrant expression of COL4A1 was identified a clinically associated with the ARC. Silencing of COL4A1 promoted the apoptosis and inhibited the proliferation of HLE-B3 by blocking the cell cycle. Moreover, COL4A1 gene silence didn't affect the cytoskeleton of HLE-B3 but down-regulated the Collagen type IV Alpha 2 Chain (COL4A2), paired box 6 (PAX6), procollagen-lysine 2-oxoglutarate 5-dioxygenases 1 (PLOD1) and procollagen-lysine 2-oxoglutarate 5-dioxygenases 2 (PLOD2) expression levels in HLE-B3 cells. Silencing the COL4A1 gene induced EMT of the HLE-B3 cells by promoting the transforming growth factor beta (TGF-ß) expression. CONCLUSION: Silencing of COL4A1 induces S-phase arrest, also inhibits the proliferation and enhance HLE-B3 apoptosis and EMT, and down-regulates the expression of COL4A2, PAX6, PLOD1 and PLOD2. Thus, the expression alteration of COL4A1 may play a critical role in the pathogenesis of ARC.

A proteomical study on the radiosensitized target molecules of fuzheng zengxiao formula in pulmonary adenocarcinoma nude mice model.

OBJECTIVE: To investigate the radiosensitized target of Fuzheng Zengxiao Formula. METHODS: The pulmonary adenocarcinoma (PAa) nude mice of tumor transplantation model were prepared and divided into four groups: Group I (blank control group, n = 10), Group II (simple radiotherapy group, n = 10), Group III (radiotherapy plus Fuzheng Zengxiao Formula, n = 10) and Group IV (radiotherapy plus metronidazole, n = 10). Radiation of X-rays was given to the tumors in Group I, II and III when they were averagely about 1 centimetre in diameter. 23 hours later, the tumors were taken, the total proteins were extracted, and the protein contents were determined. The proteins were isolated with two dimensional gel electrophoresis, and the differentially expressed proteins were analyzed with mass spectrometry and identified by protein database. RESULTS: Six significant proteins, including apolipoprotein E, ceratin75, S100A9, cyclophilin A, S100A10 and hemoglobin, were determined. Compared with Group I, apolipoprotein E and ceratin75 highly expressed in the Group II; compared with Group II, S100A9, cyclophilin A and hemoglobin had high expression in the Group III; compared with Group II, S100A9, cyclophilin A, S100A10 and hemoglobin had high expression in the Group IV; compared with Group IV, S100A9 and S100A10 had low expression and hemoglobin had high expression in Group III. CONCLUSION: The radiosensitization of Fuzheng Zengxiao Formula is related with the improvement of hypoxia state; and possibly S100A9 and cyclophilin A are the target proteins of Fuzheng Zengxiao Formula in radiosensitization.