Microtubules offset growth site from the cell centre in fission yeast

Abstract

The design principles that underlie cellular morphogenetic mechanisms are central to understanding the generation of cell form. We have investigated the constraints governing the formation and positioning of new growth zones in the fission yeast cell and have shown that establishment of a new axis of polarity is independent of microtubules and that in the absence of microtubules a new growth zone is activated near the nucleus in the middle of the cell. Activation of a new growth zone can occur at any stage of the cell cycle as long as the nucleus is a sufficient distance away from previously growing ends. The positioning of growth zones is regulated by the polarity marker Tea1 delivered by microtubules; cells with short microtubules locate the growth zone near the region where the microtubules terminate. We propose a model for the activation of new growth zones comprising a long-range laterally inhibitory component and a self-activating positive local component that is delivered to cell ends by Tea1 and the microtubules. The principle of this symmetry-breaking design may also apply to the morphogenesis of other cells.

Tea4-phosphatase I landmark promotes local growth by dual Cdc42 GEF recruitment and GAP exclusion

“…3B for quantification). The observation of bulges in tea4D, but not wild-type cells, suggests that endogenous growth sites compete with establishment of new growth sites, as has been previously proposed (Castagnetti et al, 2007). The extended length of cells expressing the Cdr2-Tea4N fusion might thus also favor the appearance of bulges.…”

Coordinate control of terminal dendrite patterning and dynamics by the membrane protein Raw

“…For example, positioning the nucleus at the cell center and growth zones at the cell periphery depends on positional information from the microtubule cytoskeleton in Schizosaccharomyces pombe (Bähler and Pringle, 1998;Castagnetti et al, 2007;Hagan and Yanagida, 1997). Several lines of evidence support the existence of distinct subcompartments in axons and dendrites, but the forms of intracellular positional information and the coordinate systems that guide the development of these subcompartments have not been extensively characterized.…”

Stress-regulated kinase pathways in the recovery of tip growth and microtubule dynamics following osmotic stress inS. pombe

“…Immediately following cytokinesis, growth initiates at the 'old' end -that which existed before division. The 'new' end, which was created by division, does not grow until cells have reached a critical size threshold and entered G2 phase of the cell cycle (Castagnetti et al, 2007;Mitchison and Nurse, 1985), whereupon growth starts from the new end, a step referred to as new-end take off (NETO). Since growth from the old tip persists after NETO, NETO constitutes a rate change point (RCP), as the overall rate of growth is increased by the activation of this new site (Mitchison and Nurse, 1985).…”

“…Since growth from the old tip persists after NETO, NETO constitutes a rate change point (RCP), as the overall rate of growth is increased by the activation of this new site (Mitchison and Nurse, 1985). The restriction of new tip growth to G2 phase can be overcome by disruption of microtubules, but the requirement to achieve a minimal cell size cannot be overcome (Castagnetti et al, 2007).…”

“…Thus, size control influences both tip growth and cell-cycle commitment (Castagnetti et al, 2007;Fantes, 1977;Mitchison and Nurse, 1985;Rupes et al, 2001).…”