Scaling of subcellular structures with cell length through decelerated growth

Abstract

How cells tune the size of their subcellular parts to scale with cell size is a fundamental question in cell biology. Until now, most studies on the size control of organelles and other subcellular structures have focused on scaling relationships with cell volume, which can be explained by limiting pool mechanisms. Here, we uncover a distinct scaling relationship with cell length rather than volume, revealed by mathematical modeling and quantitative imaging of yeast actin cables. The extension rate of cables decelerates as they approach the rear of the cell, until cable length matches cell length. Further, the deceleration rate scales with cell length. These observations reveal a new mode of scaling that senses the linear dimensions of a cell.One Sentence SummaryAs actin cables in yeast cells grow longer, their extension rate decelerates, enabling the cable length to match cell length.

How to Assemble a Scale-Invariant Gradient

“…Another possible use for such a gradient could be in controlling the self-assembly of linear structures such as actin cables and flagella, which are precisely scaled to the linear dimensions of the cell [29], [30], [31]. For example, a recent study of actin cables in yeast found that when cells were mutated to grow abnormally large, the actin cables assembled to a length that was proportional to the cell radius [32]. A hypothesized explanation of this phenomena is the presence of a scale-invariant gradient of depolymerizing activity.…”