Limits...
Ca2+ influx and phosphoinositide signalling are essential for the establishment and maintenance of cell polarity in monospores from the red alga Porphyra yezoensis.

Li L, Saga N, Mikami K - J. Exp. Bot. (2009)

Bottom Line: The results indicate that the inhibition of the establishment of cell polarity, as judged by the ability of F-actin to localize asymmetrically, cell wall synthesis, and development into germlings, occurred when monospores were treated with inhibitors of the Ca2+ permeable channel, phospholipase C (PLC), diacylglycerol kinase, and inositol-1,4,5-trisphosphate receptor.Moreover, it was also found that light triggered the establishment of cell polarity via photosynthetic activity but not its direction, indicating that the Ca2+ influx and PLC activation required for the establishment of cell polarity are light dependent.Taken together, these findings suggest that there is functional diversity between the PLC and PLD signalling systems in terms of the formation of cell polarity; the former being critical for the light-dependent establishment of cell polarity and the latter playing a role in the maintenance of established cell polarity.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Fisheries Sciences, Hokkaido University, Hakodate 041-8611, Japan.

ABSTRACT
The asymmetrical distribution of F-actin directed by cell polarity has been observed during the migration of monospores from the red alga Porphyra yezoensis. The significance of Ca2+ influx and phosphoinositide signalling during the formation of cell polarity in migrating monospores was analysed pharmacologically. The results indicate that the inhibition of the establishment of cell polarity, as judged by the ability of F-actin to localize asymmetrically, cell wall synthesis, and development into germlings, occurred when monospores were treated with inhibitors of the Ca2+ permeable channel, phospholipase C (PLC), diacylglycerol kinase, and inositol-1,4,5-trisphosphate receptor. Moreover, it was also found that light triggered the establishment of cell polarity via photosynthetic activity but not its direction, indicating that the Ca2+ influx and PLC activation required for the establishment of cell polarity are light dependent. By contrast, inhibition of phospholipase D (PLD) prevented the migration of monospores but not the asymmetrical localization of F-actin. Taken together, these findings suggest that there is functional diversity between the PLC and PLD signalling systems in terms of the formation of cell polarity; the former being critical for the light-dependent establishment of cell polarity and the latter playing a role in the maintenance of established cell polarity.

Show MeSH
PLD participates in the maintenance of cell polarity in monospores. (A) Effects of PLD inhibitor on the motility and development of monospores. Freshly released monospores incubated with an increasing concentration of 0.05–0.4% 1-butanol and 0.4% t-butanol for 3 h (a) and 24 h (b). Columns and vertical bars represent the mean and SD, respectively (n=3). (B) Effects of PLD inhibitor on the F-actin organization and renascent cell wall formation. Freshly released monospores incubated with 0.4% 1-butanol (a, c, e, g) and its analogue t-butanol (b, d, f, h) for 3 h (a–d) and 8 h (e–h). The organization of F-actin in 1-butanol and t-butanol treated monospores are indicated in (a, e) and (b, f). Renascent cell wall synthesis in 1-butanol and t-butanol treated monospores are indicated in (c, g) and (d, h). Left and right photographs in each panel show bright-field and fluorescent images, respectively. Scale bars=5 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC2724695&req=5

fig4: PLD participates in the maintenance of cell polarity in monospores. (A) Effects of PLD inhibitor on the motility and development of monospores. Freshly released monospores incubated with an increasing concentration of 0.05–0.4% 1-butanol and 0.4% t-butanol for 3 h (a) and 24 h (b). Columns and vertical bars represent the mean and SD, respectively (n=3). (B) Effects of PLD inhibitor on the F-actin organization and renascent cell wall formation. Freshly released monospores incubated with 0.4% 1-butanol (a, c, e, g) and its analogue t-butanol (b, d, f, h) for 3 h (a–d) and 8 h (e–h). The organization of F-actin in 1-butanol and t-butanol treated monospores are indicated in (a, e) and (b, f). Renascent cell wall synthesis in 1-butanol and t-butanol treated monospores are indicated in (c, g) and (d, h). Left and right photographs in each panel show bright-field and fluorescent images, respectively. Scale bars=5 μm.

Mentions: The effects of R59022 indicate the importance of PA in polarity establishment in monospores (Fig. 3Ba, b). Since PA is also produced by PLD from PC (Munnik, 2001), it was examined if PLD-dependent PA production is required for the formation of cell polarity in monospores. When monospores were treated with 1-butanol at an increasing concentration from 0.05% to 0.4% (v/v), the rate of migration and germling formation decreased in a dose-dependent manner (Fig. 4Aa, b). Moreover, in monospores treated with 0.4% 1-butanol for 3 h, F-actin was asymmetrically localized (Fig. 4Ba); however, cells presented as a round shape without a cell wall (Fig. 4Bc). On the other hand, 8 h treatment of monospores resulted in symmetrically distributed F-actin and no cell wall (Fig. 4Be, g). Incubation with 0.4% 1-butanol did not kill monospores even after 24 h incubation and the inhibitory effect of 1-butanol was recovered after washout with ESL (data not shown). By contrast, monospores treated with 0.4% t-butanol were able to migrate normally and form germlings (Fig. 4Aa,b); after 3 h treatment, monospores migrated with polarized F-actin and a renascent cell wall (Fig. 4Bb, d), while 8 h treatment resulted in adhesion to the substrate and the development of germlings with an accumulation of F-actin in the bottom and also with a thick cell wall (Fig. 4Bf, h). From these results, since inhibition of PLD activity did not disrupt the formation of F-actin asymmetry but prevented its maintenance, it was concluded that PLD participates in the maintenance, but not in the establishment, of cell polarity during the early development of monospores.


Ca2+ influx and phosphoinositide signalling are essential for the establishment and maintenance of cell polarity in monospores from the red alga Porphyra yezoensis.

Li L, Saga N, Mikami K - J. Exp. Bot. (2009)

PLD participates in the maintenance of cell polarity in monospores. (A) Effects of PLD inhibitor on the motility and development of monospores. Freshly released monospores incubated with an increasing concentration of 0.05–0.4% 1-butanol and 0.4% t-butanol for 3 h (a) and 24 h (b). Columns and vertical bars represent the mean and SD, respectively (n=3). (B) Effects of PLD inhibitor on the F-actin organization and renascent cell wall formation. Freshly released monospores incubated with 0.4% 1-butanol (a, c, e, g) and its analogue t-butanol (b, d, f, h) for 3 h (a–d) and 8 h (e–h). The organization of F-actin in 1-butanol and t-butanol treated monospores are indicated in (a, e) and (b, f). Renascent cell wall synthesis in 1-butanol and t-butanol treated monospores are indicated in (c, g) and (d, h). Left and right photographs in each panel show bright-field and fluorescent images, respectively. Scale bars=5 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC2724695&req=5

fig4: PLD participates in the maintenance of cell polarity in monospores. (A) Effects of PLD inhibitor on the motility and development of monospores. Freshly released monospores incubated with an increasing concentration of 0.05–0.4% 1-butanol and 0.4% t-butanol for 3 h (a) and 24 h (b). Columns and vertical bars represent the mean and SD, respectively (n=3). (B) Effects of PLD inhibitor on the F-actin organization and renascent cell wall formation. Freshly released monospores incubated with 0.4% 1-butanol (a, c, e, g) and its analogue t-butanol (b, d, f, h) for 3 h (a–d) and 8 h (e–h). The organization of F-actin in 1-butanol and t-butanol treated monospores are indicated in (a, e) and (b, f). Renascent cell wall synthesis in 1-butanol and t-butanol treated monospores are indicated in (c, g) and (d, h). Left and right photographs in each panel show bright-field and fluorescent images, respectively. Scale bars=5 μm.
Mentions: The effects of R59022 indicate the importance of PA in polarity establishment in monospores (Fig. 3Ba, b). Since PA is also produced by PLD from PC (Munnik, 2001), it was examined if PLD-dependent PA production is required for the formation of cell polarity in monospores. When monospores were treated with 1-butanol at an increasing concentration from 0.05% to 0.4% (v/v), the rate of migration and germling formation decreased in a dose-dependent manner (Fig. 4Aa, b). Moreover, in monospores treated with 0.4% 1-butanol for 3 h, F-actin was asymmetrically localized (Fig. 4Ba); however, cells presented as a round shape without a cell wall (Fig. 4Bc). On the other hand, 8 h treatment of monospores resulted in symmetrically distributed F-actin and no cell wall (Fig. 4Be, g). Incubation with 0.4% 1-butanol did not kill monospores even after 24 h incubation and the inhibitory effect of 1-butanol was recovered after washout with ESL (data not shown). By contrast, monospores treated with 0.4% t-butanol were able to migrate normally and form germlings (Fig. 4Aa,b); after 3 h treatment, monospores migrated with polarized F-actin and a renascent cell wall (Fig. 4Bb, d), while 8 h treatment resulted in adhesion to the substrate and the development of germlings with an accumulation of F-actin in the bottom and also with a thick cell wall (Fig. 4Bf, h). From these results, since inhibition of PLD activity did not disrupt the formation of F-actin asymmetry but prevented its maintenance, it was concluded that PLD participates in the maintenance, but not in the establishment, of cell polarity during the early development of monospores.

Bottom Line: The results indicate that the inhibition of the establishment of cell polarity, as judged by the ability of F-actin to localize asymmetrically, cell wall synthesis, and development into germlings, occurred when monospores were treated with inhibitors of the Ca2+ permeable channel, phospholipase C (PLC), diacylglycerol kinase, and inositol-1,4,5-trisphosphate receptor.Moreover, it was also found that light triggered the establishment of cell polarity via photosynthetic activity but not its direction, indicating that the Ca2+ influx and PLC activation required for the establishment of cell polarity are light dependent.Taken together, these findings suggest that there is functional diversity between the PLC and PLD signalling systems in terms of the formation of cell polarity; the former being critical for the light-dependent establishment of cell polarity and the latter playing a role in the maintenance of established cell polarity.

View Article: PubMed Central - PubMed

Affiliation: Graduate School of Fisheries Sciences, Hokkaido University, Hakodate 041-8611, Japan.

ABSTRACT
The asymmetrical distribution of F-actin directed by cell polarity has been observed during the migration of monospores from the red alga Porphyra yezoensis. The significance of Ca2+ influx and phosphoinositide signalling during the formation of cell polarity in migrating monospores was analysed pharmacologically. The results indicate that the inhibition of the establishment of cell polarity, as judged by the ability of F-actin to localize asymmetrically, cell wall synthesis, and development into germlings, occurred when monospores were treated with inhibitors of the Ca2+ permeable channel, phospholipase C (PLC), diacylglycerol kinase, and inositol-1,4,5-trisphosphate receptor. Moreover, it was also found that light triggered the establishment of cell polarity via photosynthetic activity but not its direction, indicating that the Ca2+ influx and PLC activation required for the establishment of cell polarity are light dependent. By contrast, inhibition of phospholipase D (PLD) prevented the migration of monospores but not the asymmetrical localization of F-actin. Taken together, these findings suggest that there is functional diversity between the PLC and PLD signalling systems in terms of the formation of cell polarity; the former being critical for the light-dependent establishment of cell polarity and the latter playing a role in the maintenance of established cell polarity.

Show MeSH