Integration of Light Signals by the Retinoblastoma Pathway in the Control of S Phase Entry in the Picophytoplanktonic Cell Ostreococcus

• DOI: 10.1371/journal.pgen.1000957
• Publication Date: 2010-05-20T19:03:59Z
• Authors: Mickael Moulager; Florence Corellou; Valérie Vergé; Marie-Line Escande; François-Yves Bouget
• Keywords: Retinoblastoma protein; E2F; Cyclin A

Although the decision to proceed through cell division depends largely on metabolic status or size of cell, timing is often set by internal clocks such as circadian clock. Light a major cue for clock entrainment, and photosynthetic organisms it also main source energy supporting growth prior division. Little known about how light signals are integrated in control S phase entry. Here, we present an study light-dependent regulation marine green alga Ostreococcus. During early G1, genes were transcribed independently amount light, did not occur 6 hours after dawn. In contrast commitment translation G1 A-type cyclin dependent cAMP–dependent manner. CyclinA was shown interact with Retinoblastoma (Rb) protein during phase. Down-regulating Rb bypassed requirement cAMP without altering Overexpression overrode entry led Therefore, pathway appears integrate Ostreococcus, though differential transcriptional posttranscriptional regulations cyclin. Furthermore, pathway, which regulates synthesis CyclinA. We discuss relative involvements time/clock photoperiodic