Increased expression of SIRT2 is a novel marker of cellular senescence and is dependent on wild type p53 status

Abstract

Sirtuins (SIRT) belonging to the NADC dependent histone deacetylase III class of enzymes have emerged as master regulators of metabolism and longevity. However, their role in prevention of organismal aging and cellular senescence still remains controversial. In the present study, we now report upregulation of SIRT2 as a specific feature associated with stress induced premature senescence but not with either quiescence or cell death. Additionally, increase in SIRT2 expression was noted in different types of senescent conditions such as replicative and oncogene induced senescence using multiple cell lines. Induction of SIRT2 expression during senescence was dependent on p53 status as depletion of p53 by shRNA prevented its accumulation. Chromatin immunoprecipitation revealed the presence of p53 binding sites on the SIRT2 promoter suggesting its regulation by p53, which was also corroborated by the SEAP reporter assay. Overexpression or knockdown of SIRT2 had no effect on stress induced premature senescence, thereby indicating that SIRT2 increase is not a cause of senescence; rather it is an effect linked to senescence-associated changes. Overall, our results suggest SIRT2 as a promising marker of cellular senescence at least in cells with wild type p53 status.

Differentially regulated gene expression in quiescence versus senescence and identification of ARID5A as a quiescence associated marker

“…CTSB (Cathepsin B) showed an opposite trend of expression; upregulated in senescence and downregulated in quiescence. Further, we had earlier reported a specific increase in SIRT2 levels only in senescent cells, but not in quiescence (Anwar et al, ) and hence this data is not shown here.…”

“…For growth curve at indicated time, cells were fixed in ethanol for 10 min followed by staining with 0.05% crystal violet, which was solubilized in methanol and absorbance was checked at 590 nm using a spectrophotometer. The condition for induction of senescence has been previously described by us (Anwar et al, ). Briefly, for induction of senescence cells were treated with doxorubicin (1 μM, 2 hr treatment) followed by re‐culturing them in fresh medium containing 10% FBS for 192 hr (8 day).…”

“…Recently, we reported increased expression of SIRT2 as a senescence specific marker which remained unaffected in conditions of quiescence (Anwar, Khosla, & Ramakrishna, ). Briefly, in the present work we have now performed gene expression profiling and compared gene signatures unique to senescence and quiescence, using U2OS cells.…”

Wild‐type p53 regulates OTOP2 transcription through DNA loop alteration of the promoter in colorectal cancer

“…We confirmed the precise binding sites of p53 and also determined that mtp53 compromised the interaction with the otop2 promoter. p53-mediated gene regulation has been well studied in many genes and cancers [11][12][13] and is also exhibited by the loss-of-function and gainof-function phenomenon to reprogram genomic transcription and drive oncogenesis [14]. Here, we suggest that mtp53 loses the ability to activate the transcriptional process of otop2, which promotes tumorigenesis.…”

Senescent stromal cells promote cancer resistance through SIRT1 loss-potentiated overproduction of small extracellular vesicles

“…Upon cellular senescence, DNA damage-associated concomitant decline of SIRT1/2 was indeed also observed in a human primary fibroblast line BJ 36 , essentially supporting our data. SIRT1 regulates diverse cellular targets and correlates with organismal aging, while SIRT2 has been reported to be marker of cellular senescence in certain cancer types such as osteosarcoma 37,38 . Although loss of SIRT1 enhances the secretion of exosomes by breast cancer cells, whether or not this occurs in stromal cells remains unclear.…”