Rho-GTPase–dependent filamentous actin dynamics coordinate vesicle targeting and exocytosis during tip growth
نویسندگان
چکیده
The dynamic activity of tip-localized filamentous actin (F-actin) in pollen tubes is controlled by counteracting RIC4 and RIC3 pathways downstream of the ROP1 guanosine triphosphatase promoting actin assembly and disassembly, respectively. We show here that ROP1 activation is required for both the polar accumulation and the exocytosis of vesicles at the plasma membrane apex. The apical accumulation of exocytic vesicles oscillated in phase with, but slightly behind, apical actin assembly and was enhanced by overexpression of RIC4. However, RIC4 overexpression inhibited exocytosis, and this inhibition could be suppressed by latrunculin B treatment or RIC3 overexpression. We conclude that RIC4-dependent actin assembly is required for polar vesicle accumulation, whereas RIC3-mediated actin disassembly is required for exocytosis. Thus ROP1-dependent F-actin dynamics control tip growth through spatiotemporal coordination of vesicle targeting and exocytosis.
منابع مشابه
A Rho family GTPase controls actin dynamics and tip growth via two counteracting downstream pathways in pollen tubes
Tip growth in neuronal cells, plant cells, and fungal hyphae is known to require tip-localized Rho GTPase, calcium, and filamentous actin (F-actin), but how they interact with each other is unclear. The pollen tube is an exciting model to study spatiotemporal regulation of tip growth and F-actin dynamics. An Arabidopsis thaliana Rho family GTPase, ROP1, controls pollen tube growth by regulating...
متن کاملROP Gtpase–Dependent Dynamics of Tip-Localized F-Actin Controls Tip Growth in Pollen Tubes
Tip-growing pollen tubes provide a useful model system to study polar growth. Although roles for tip-focused calcium gradient and tip-localized Rho-family GTPase in pollen tube growth is established, the existence and function of tip-localized F-actin have been controversial. Using the green fluorescent protein-tagged actin-binding domain of mouse talin, we found a dynamic form of tip-localized...
متن کاملF-Actin Meditated Focusing of Vesicles at the Cell Tip Is Essential for Polarized Growth
34 35 Filamentous actin has been shown to be essential for tip growth in an array of 36 plant models, including Physcomitrella patens. One hypothesis is that diffusion 37 can transport secretory vesicles, while actin plays a regulatory role during 38 secretion. Alternatively, it is possible that actin-based transport is necessary to 39 overcome vesicle transport limitations to sustain secretion...
متن کاملThe microtubule-associated Rho activating factor GEF-H1 interacts with exocyst complex to regulate vesicle traffic.
The exocyst complex plays a critical role in targeting and tethering vesicles to specific sites of the plasma membrane. These events are crucial for polarized delivery of membrane components to the cell surface, which is critical for cell motility and division. Though Rho GTPases are involved in regulating actin dynamics and membrane trafficking, their role in exocyst-mediated vesicle targeting...
متن کاملA Tip-Localized RhoGAP Controls Cell Polarity by Globally Inhibiting Rho GTPase at the Cell Apex
BACKGROUND Highly elongated eukaryotic cells (e.g., neuronal axons, fungal hyphae, and pollen tubes) are generated through continuous apically restricted growth (tip growth), which universally requires tip-localized Rho GTPases. We used the oscillating pollen tube as a model system to determine the function and regulation of Rho GTPases in tip growth. Our previous work showed that the spatiotem...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید
ثبت ناماگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید
ورودعنوان ژورنال:
- The Journal of Cell Biology
دوره 181 شماره
صفحات -
تاریخ انتشار 2008