Reactive oxygen species-mediated senescence is accelerated by inhibiting Cdk2 in Idh2-deficient conditions
AGING-US
Authors: Chae, Unbin; Park, Jeen-Woo; Lee, Sang-Rae; Lee, Hong Jun; Lee, Hyun-Shik; Lee, Dong-Seok
Abstract
Among the many factors that promote cellular senescence, reactive oxygen species (ROS) are a focus of intense research because of their critical role in accelerating cellular senescence and initiating senescence-related diseases that can be fatal. Therefore, maintaining the proper balance of ROS in cells is a key method to alleviate senescence. Recent studies have found that isocitrate dehydrogenase 2 (IDH2), a critical enzyme of the tricarboxylic acid cycle, participates in ROS generation and in cellular dysfunction that is induced by excessive levels of ROS. Loss of IDH2 induces mitochondrial dysfunction that promotes excessive ROS generation and the development of several diseases. The results of this study suggest that Idh2 plays an important role in cellular senescence. Idh2 deficiency resulted in senescence-associated phenotypes and increased levels of senescence marker proteins in mouse embryonic fibroblasts and tissues. Furthermore, excessive ROS were generated in Idh2-deficient conditions, promoting cellular senescence by inducing cell cycle arrest through cyclin-dependent kinase 2. These results indicate that loss of Idh2 is a critical factor in regulating cellular senescence. Taken together, our findings contribute to the field of senescence research and suggest that IDH2 is a potential target of future anti-senescence studies.
Non-ossifying fibroma: A RAS-MAPK driven benign bone neoplasm
JOURNAL OF PATHOLOGY
Authors: Bovee, Judith V. M. G.; Hogendoorn, Pancras C. W.
Abstract
Non-ossifying fibroma (NOF) has been an intriguing entity since its first description. It is the most common bone tumour, is usually asymptomatic affecting children and adolescents, is composed of a heterogeneous cell population, and undergoes spontaneous regression after puberty. In a recent article in The Journal of Pathology, Baumhoer and colleagues demonstrate mutations activating the RAS-MAPK pathway (KRAS, FGFR1 and NF1) in similar to 80% of the tumours. Activation of the RAS-MAPK pathway by somatic mutations is found in a plethora of tumour types, both benign and malignant, while germline mutations cause a wide range of syndromes collectively termed the RASopathies. Their findings indicate that NOF, for long thought to be reactive, should be considered a true neoplasm. Moreover, their data suggest that only a subset of cells in the lesion contain the mutation. A second cell population consisting of histiocytes and osteoclast-like giant cells appears to be reacbenign and locally aggressive bone tumours and seems essential for tumourigenesis. The spontaneous regtive. This intimate relation between WT and mutant cells is also frequently encountered in other ression remains enigmatic and it is tempting to speculate that pubertal hormonal signalling, especially increased oestrogen levels, affect the balance between mutant and WT cells. (c) 2019 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.