| 1. |
- Boutté, Yohann, et al.
(författare)
-
Cellular processes relying on sterol function in plants
- 2009
-
Ingår i: Current opinion in plant biology. - : Elsevier BV. - 1369-5266 .- 1879-0356. ; 12:6, s. 705-713
-
Tidskriftsartikel (refereegranskat)abstract
- Sterols are lipophilic membrane components essential for diverse cellular functions. The plant sterol biosynthesis pathway has largely been defined by biochemical approaches. Sterol function has been investigated by the pharmacological and genetic manipulation of sterol biosynthesis. However, mechanisms by which sterols influence cellular processes and targets of sterol function remain largely unknown. During the last two years, new Arabidopsis sterol biosynthesis mutants have been characterized. Their analysis has revealed the contributions of known and alternative routes of sterol biosynthesis to various cellular processes. Subcellular localization and trafficking of a sterol-binding protein have been investigated and first steps towards in vivo characterization of sterol-enriched membrane domains have been taken. Finally, mechanistic insight into the role of plant sterols during endocytosis and the establishment of cell polarity has been obtained.
|
|
| 2. |
- Boutté, Yohann, et al.
(författare)
-
Endocytosis restricts Arabidopsis KNOLLE syntaxin to the cell division plane during late cytokinesis
- 2010
-
Ingår i: EMBO Journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 29:3, s. 546-58
-
Tidskriftsartikel (refereegranskat)abstract
- Cytokinesis represents the final stage of eukaryotic cell division during which the cytoplasm becomes partitioned between daughter cells. The process differs to some extent between animal and plant cells, but proteins of the syntaxin family mediate membrane fusion in the plane of cell division in diverse organisms. How syntaxin localization is kept in check remains elusive. Here, we report that localization of the Arabidopsis KNOLLE syntaxin in the plane of cell division is maintained by sterol-dependent endocytosis involving a clathrin- and DYNAMIN-RELATED PROTEIN1A-dependent mechanism. On genetic or pharmacological interference with endocytosis, KNOLLE mis-localizes to lateral plasma membranes after cell-plate fusion. Fluorescence-loss-in-photo-bleaching and fluorescence-recovery-after-photo-bleaching experiments reveal lateral diffusion of GFP-KNOLLE from the plane of division to lateral membranes. In an endocytosis-defective sterol biosynthesis mutant displaying lateral KNOLLE diffusion, KNOLLE secretory trafficking remains unaffected. Thus, restriction of lateral diffusion by endocytosis may serve to maintain specificity of syntaxin localization during late cytokinesis.
|
|
| 3. |
- Boutté, Yohann, et al.
(författare)
-
Fluorescent in situ visualization of sterols in Arabidopsis roots
- 2011
-
Ingår i: Nature Protocols. - : Springer Science and Business Media LLC. - 1754-2189 .- 1750-2799. ; 6:4, s. 446-456
-
Tidskriftsartikel (refereegranskat)abstract
- Sterols are eukaryotic membrane components with crucial roles in diverse cellular processes. Elucidation of sterol function relies on development of tools for in situ sterol visualization. Here we describe protocols for in situ sterol localization in Arabidopsis thaliana root cells, using filipin as a specific probe for detection of fluorescent filipin-sterol complexes. Currently, filipin is the only established tool for sterol visualization in plants. Filipin labeling can be performed on aldehyde-fixed samples, largely preserving fluorescent proteins and being compatible with immunocytochemistry. Filipin can also be applied for probing live cells, taking into account the fact that it inhibits sterol-dependent endocytosis. The experimental procedures described are designed for fluorescence detection by confocal laser-scanning microscopy with excitation of filipin-sterol complexes at 364 nm. The protocols require 1 d for sterol covisualization with fluorescent proteins in fixed or live roots and 2 d for immunocytochemistry on whole-mount roots.
|
|
| 4. |
- Boutté, Yohann, et al.
(författare)
-
Immunocytochemical fluorescent in situ visualization of proteins in Arabidopsis
- 2014
-
Ingår i: Arabidopsis protocols. - Totowa, NJ : Humana Press. ; 1062:1062, s. 453-472
-
Bokkapitel (refereegranskat)abstract
- The understanding of cellular and subcellular functions often relies on the ability to visualize proteins as close as possible to their endogenous locations. A number of immunocytochemical techniques have been developed to detect proteins in situ using specific antibodies raised against proteins of interest. Here, we describe in detail two protocols commonly, successfully employed in Arabidopsis research. The first allows for immunolocalization of proteins in whole-mount Arabidopsis roots without the need for physical sectioning. The second allows for immunolocalization of proteins on semi-thin microtome sections of wax-embedded swamples. This approach is particularly useful when sectioning of Arabidopsis roots or other thicker plant organs is required for immunolocalization. We provide step-by-step protocols with extensive troubleshooting for both the whole-mount and sectioning protocols. Furthermore, critical steps, advantages, and limitations of the two protocols described here are discussed.
|
|
| 5. |
- Boutté, Yohann, et al.
(författare)
-
Mechanisms of auxin-dependent cell and tissue polarity
- 2007
-
Ingår i: Current opinion in plant biology. - : Elsevier. - 1369-5266 .- 1879-0356. ; 10:6, s. 616-623
-
Tidskriftsartikel (refereegranskat)abstract
- The establishment of cellular asymmetries and their coordination within the tissue layer are fundamental to the development of multicellular organisms. In plants, the induction and coordination of cell polarity have classically been attributed to involve the hormone auxin and its flow. However, the underlying mechanisms have only recently been addressed at the molecular level. We review progress on the characterisation of the auxin influx and efflux carrier properties of specific plasma membrane proteins, mechanisms underlying their delivery to and internalisation from the plasma membrane, their endocytic transport and degradation. We discuss mechanisms of auxin gradient, transport and response action during the coordination of polarity, along with the downstream involvement of Rho-of-plant small GTPases during the execution of cell polarity.
|
|
| 6. |
- Fischer, Urs, et al.
(författare)
-
Lipid function in plant cell polarity.
- 2004
-
Ingår i: Current opinion in plant biology. - : Elsevier BV. - 1369-5266 .- 1879-0356. ; 7:6, s. 670-6
-
Tidskriftsartikel (refereegranskat)abstract
- The establishment and maintenance of cell polarity play pivotal roles during plant development. During the past five years, proteins that are required for different aspects of plant cell polarity have been identified. However, the functions of lipids and their interactions with proteins that mediate polarity remained largely unaddressed. Recent genetic studies have discovered cell and tissue polarity mutants that have defects in sterol composition, glycosylphosphatidylinositol-anchored proteins, glycosylphosphatidylinositol biosynthesis and phospholipid signalling. Analyses of the affected gene products have provided a first glance at the roles of lipids in cell polarity signalling, as well as in the trafficking and anchoring of polar proteins.
|
|
| 7. |
- Fischer, Urs, et al.
(författare)
-
Planar polarity of root hair positioning in Arabidopsis
- 2007
-
Ingår i: Biochemical Society Transactions. - 0300-5127 .- 1470-8752. ; 35:Pt 1, s. 149-151
-
Tidskriftsartikel (refereegranskat)abstract
- The co-ordinated polarity of cells within the plane of a single tissue layer (planar polarity) is intensively studied in animal epithelia but has only recently been systematically analysed in plants. The polar positioning of hairs in the root epidermis of Arabidopsis thaliana provides an easily accessible system for the functional dissection of a plant-specific planar polarity. Recently, mutants originally isolated in genetic screens for defects in root hair morphogenesis and changes in the sensitivity to or the production of the plant hormones auxin and ethylene have identified players that contribute to polar root hair placement. Here, we summarize and discuss recent progress in research on polar root hair positioning from studies in Arabidopsis.
|
|
| 8. |
- Fischer, Urs, et al.
(författare)
-
Vectorial information for Arabidopsis planar polarity is mediated by combined AUX1, EIN2, and GNOM activity
- 2006
-
Ingår i: Current Biology. - : Elsevier. - 0960-9822 .- 1879-0445. ; 16:21, s. 2143-2149
-
Tidskriftsartikel (refereegranskat)abstract
- Cell polarity is commonly coordinated within the plane of a single tissue layer (planar polarity), and hair positioning has been exploited as a simple marker for planar polarization of animal epithelia . The root epidermis of the plant Arabidopsis similarly reveals planar polarity of hair localization close to root tip-oriented (basal) ends of hair-forming cells . Hair position is directed toward a concentration maximum of the hormone auxin in the root tip , but mechanisms driving this plant-specific planar polarity remain elusive. Here, we report that combinatorial action of the auxin influx carrier AUX1, ETHYLENE-INSENSITIVE2 (EIN2) , and GNOM genes mediates the vector for coordinate hair positioning. In aux1;ein2;gnom eb triple mutant roots, hairs display axial (apical or basal) instead of coordinate polar (basal) position, and recruitment of Rho-of-Plant (ROP) GTPases to the hair initiation site reveals the same polar-to-axial switch. The auxin concentration gradient is virtually abolished in aux1;ein2;gnom eb roots, where locally applied auxin can coordinate hair positioning. Moreover, auxin overproduction in sectors of wild-type roots enhances planar ROP and hair polarity over long and short distances. Hence, auxin may provide vectorial information for planar polarity that requires combinatorial AUX1, EIN2, and GNOM activity upstream of ROP positioning.
|
|
| 9. |
|
|
| 10. |
- Gendre, Delphine, et al.
(författare)
-
Conserved Arabidopsis ECHIDNA protein mediates trans-Golgi-network trafficking and cell elongation
- 2011
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 108:19, s. 8048-8053
-
Tidskriftsartikel (refereegranskat)abstract
- Multiple steps of plant growth and development rely on rapid cell elongation during which secretory and endocytic trafficking via the trans-Golgi network (TGN) plays a central role. Here, we identify the ECHIDNA (ECH) protein from Arabidopsis thaliana as a TGN-localized component crucial for TGN function. ECH partially complements loss of budding yeast TVP23 function and a Populus ECH complements the Arabidopsis ech mutant, suggesting functional conservation of the genes. Compared with wild-type, the Arabidopsis ech mutant exhibits severely perturbed cell elongation as well as defects in TGN structure and function, manifested by the reduced association between Golgi bodies and TGN as well as mislocalization of several TGN-localized proteins including vacuolar H(+)-ATPase subunit a1 (VHA-a1). Strikingly, ech is defective in secretory trafficking, whereas endocytosis appears unaffected in the mutant. Some aspects of the ech mutant phenotype can be phenocopied by treatment with a specific inhibitor of vacuolar H(+)-ATPases, concanamycin A, indicating that mislocalization of VHA-a1 may account for part of the defects in ech. Hence, ECH is an evolutionarily conserved component of the TGN with a central role in TGN structure and function.
|
|
