daughter-specific transcription factors regulate cell size control in budding yeastdaughter-specific出芽酵母转录因子调节单元尺寸控制.pdf

Daughter-Specific Transcription Factors Regulate Cell Size Control in Budding Yeast 1 2 1¤ 2 2 Stefano Di Talia , Hongyin Wang , Jan M. Skotheim , Adam P. Rosebrock , Bruce Futcher , Frederick R. Cross1* 1The Rockefeller University, New York, New York, United States of America, 2 Department of Molecular Genetics and Microbiology, SUNY at Stony Brook, Stony Brook, New York, United States of America Abstract In budding yeast, asymmetric cell division yields a larger mother and a smaller daughter cell, which transcribe different genes due to the daughter-specific transcription factors Ace2 and Ash1. Cell size control at the Start checkpoint has long been considered to be a main regulator of the length of the G1 phase of the cell cycle, resulting in longer G1 in the smaller daughter cells. Our recent data confirmed this concept using quantitative time-lapse microscopy. However, it has been proposed that daughter-specific, Ace2-dependent repression of expression of the G1 cyclin CLN3 had a dominant role in delaying daughters in G1. We wanted to reconcile these two divergent perspectives on the origin of long daughter G1 times. We quantified size control using single-cell time-lapse imaging of fluorescently labeled budding yeast, in the presence or absence of the daughter-specific transcriptional regulators Ace2 and Ash1. Ace2 and Ash1 are not required for efficient size control, but they shift the domain of efficient size control to larger cell size, thus increasing cell size requirement for Start in daughters. Microarray and chromatin immunoprecipitation experiments show that Ace2 and Ash1 are direct transcriptional regulators o