Agarwal Payal, DeInnocentes Patricia, Bird R Curtis
Department of Pathobiology, AURIC - Auburn University Research Initiative in Cancer, Auburn, AL, 36849-5519, USA.
Scott Ritchey Research Center, College of Veterinary Medicine Auburn University, Auburn, AL, 36849, USA.
In Vitro Cell Dev Biol Anim. 2018 Oct;54(9):658-665. doi: 10.1007/s11626-018-0291-1. Epub 2018 Aug 30.
p16 is an important tumor suppressor gene encoded by the INK4A/ARF/INK4B gene locus that is conserved in humans, rodents, and canids. p16 regulates cell cycle in early G1 phase inhibiting transition out of cell cycle from G1/S phase by regulating a multi-protein control complex. p16-associated proteins, cyclin D, CDK4, and CDK6, experience expression level decreases or do not change during cell differentiation and quiescence in contrast to constant p16 expression in post-proliferative cell phases. We hypothesized that p16 has alternate binding partners, other than classical proliferation-associated proteins such as CDKs, in these post-proliferative cell phases. Using co-immunoprecipitation, we have identified 14-3-3σ as a potential alternate binding partner for p16 in quiescent post-proliferative canine mammary cancer cells. Additionally, expression of 14-3-3σ was maintained as fibroblasts exit cell cycle and differentiate to adipocytes simultaneously with continued expression of p16. Based on these results, we suggest that 14-3-3σ protein may be an alternative binding partner for p16 active during cell quiescence and may associate with p16 during cell differentiation.
p16是一种重要的肿瘤抑制基因，由INK4A/ARF/INK4B基因座编码，在人类、啮齿动物和犬科动物中保守。p16在G1期早期调节细胞周期，通过调节一种多蛋白控制复合物来抑制细胞周期从G1/S期转变。与增殖后细胞阶段中p16的持续表达相反，p16相关蛋白、细胞周期蛋白D、细胞周期蛋白依赖性激酶4（CDK4）和细胞周期蛋白依赖性激酶6（CDK6）在细胞分化和静止期间表达水平降低或不变。我们推测，在这些增殖后细胞阶段，p16除了与CDK等经典增殖相关蛋白外，还有其他替代结合伙伴。通过免疫共沉淀，我们在静止的增殖后犬乳腺癌细胞中鉴定出14-3-3σ作为p16的潜在替代结合伙伴。此外，随着成纤维细胞退出细胞周期并分化为脂肪细胞，14-3-3σ的表达与p16的持续表达同时维持。基于这些结果，我们认为14-3-3σ蛋白可能是细胞静止期间p16的替代结合伙伴，并且在细胞分化过程中可能与p16相关联。
