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Sirkadiyen saat, hücre döngüsü ve kanser

Günlük yaşamımızda etkisi altında kaldığımız birkaç ritim vardır. Bunlardan biri de 24 saatlik zaman birimlerinden meydana gelen belirlenebilir değişiklikler ile karakterize olan sirkadiyen saattir. Bu hücresel saat hipotalamusun ön kısmındaki suprakiazmatik çekirdek tarafından kontrol edilir. Sirkadiyen saat; BMAL1, CLOCK, Cyrptochrome ve Period adı verilen dört gen/proteinden oluşan bir düzenleyici transkripsiyon- translasyon feedback döngüsünden meydana gelmiştir. CLOCK ve BMAL 1 transkripsiyon faktörüdür, Period ve Cyrptochrome’da bunların hedefidir. Period ve Cyrptochrome nükleusa girmek için sitoplazmada dimerize olur ve burada CLOCK/BMAL aktivitesini inhibe eder. Sirkadiyen saatin hücre çoğalması, DNA hasar ve tamir mekanizmaları, kontrol noktaları, apoptoz ve kanserde önemli bir role sahip olduğu bildirilmiştir.

Circadian clock, cell cycle and cancer

There are a few rhythms of our daily lives that we are under the influence. One of them is characterized by predictable changes over a 24-hour timescale called circadian clock. This cellular clock is coordinated by the suprachiasmatic nucleus in the anterior hypothalamus. The clock consist of an autoregulatory transcription-translation feedback loop compose of four genes/proteins; BMAL1, Clock, Cyrptochrome, and Period. BMAL 1 and Clock are transcriptional factors and Period and Cyrptochrome are their targets. Period and Cyrptochrome dimerize in the cytoplasm to enter the nucleus where they inhibit Clock/BMAL activity. It has been demonstrate that circadian clock plays an important role cellular proliferation, DNA damage and repair mechanisms, checkpoints, apoptosis and cancer.

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