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Polar delivery in plants; commonalities and differences to animal epithelial cells.

Kania U, Fendrych M, Friml J - Open Biol (2014)

Bottom Line: Although plant and animal cells use a similar core mechanism to deliver proteins to the plasma membrane, their different lifestyle, body organization and specific cell structures resulted in the acquisition of regulatory mechanisms that vary in the two kingdoms.In particular, cell polarity regulators do not seem to be conserved, because genes encoding key components are absent in plant genomes.In animals, much information is provided from the study of polarity in epithelial cells that exhibit basolateral and luminal apical polarities, separated by tight junctions.

View Article: PubMed Central - PubMed

Affiliation: Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria.

ABSTRACT
Although plant and animal cells use a similar core mechanism to deliver proteins to the plasma membrane, their different lifestyle, body organization and specific cell structures resulted in the acquisition of regulatory mechanisms that vary in the two kingdoms. In particular, cell polarity regulators do not seem to be conserved, because genes encoding key components are absent in plant genomes. In plants, the broad knowledge on polarity derives from the study of auxin transporters, the PIN-FORMED proteins, in the model plant Arabidopsis thaliana. In animals, much information is provided from the study of polarity in epithelial cells that exhibit basolateral and luminal apical polarities, separated by tight junctions. In this review, we summarize the similarities and differences of the polarization mechanisms between plants and animals and survey the main genetic approaches that have been used to characterize new genes involved in polarity establishment in plants, including the frequently used forward and reverse genetics screens as well as a novel chemical genetics approach that is expected to overcome the limitation of classical genetics methods.

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Design of a specific screen for PIN polarity components. PIN2proteins localize to the apical side of epidermal cells in thegravitropic wild-type line. In the pin2 mutant,PIN2 proteins do not occur, provoking the agravitropic phenotype.PIN1-HA is mislocalized in the epidermis to the basal cell side inthe PIN2::PIN1-HA;pin2 line, resulting in anagravitropic phenotype. Mutations in the putative PIN polarityregulators (repp) are predicted to restore theapical localization of PIN1 and, hence, the gravitropicphenotype.
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RSOB140017F3: Design of a specific screen for PIN polarity components. PIN2proteins localize to the apical side of epidermal cells in thegravitropic wild-type line. In the pin2 mutant,PIN2 proteins do not occur, provoking the agravitropic phenotype.PIN1-HA is mislocalized in the epidermis to the basal cell side inthe PIN2::PIN1-HA;pin2 line, resulting in anagravitropic phenotype. Mutations in the putative PIN polarityregulators (repp) are predicted to restore theapical localization of PIN1 and, hence, the gravitropicphenotype.

Mentions: Screening of mutants using the microscope by direct observation of the cellularPIN localization is very laborious and time consuming. To overcome thesedifficulties, it was necessary to translate the problem of polarity at thecellular level to a macroscopically visible phenotype that would be fast andeasy to screen. Examination of the gravitropic response of the mutagenizedtransgenic PIN2::PIN1-HA line in the pin2 mutant backgroundprovided the solution (figure 3).In wild-type plants, the apical localization of PIN2 in the root epidermisdirects the auxin flow from the root tip to the top parts of the root, enablingroot growth toward the gravity vector. In the PIN2::PIN1-HA line, the PIN1proteins localize predominantly at the basal side of epidermal cells and, thus,do not rescue the agravitropic phenotype of the pin2 mutant.Weak polarity mutants are mostly defective in PIN1 localization and exhibit abasal-to-apical polarity shift; hence, in polarity-defective mutants, the basalPIN1 proteins in the epidermis were hypothesized to be targeted to the apicaldomain, as macroscopically observed by the gravitropic growth restoration.Screening for mutants that respond to the gravity vector enabled theidentification of the repp3 mutant as a new candidate for thepolar PIN localization [134].FigureĀ 3.


Polar delivery in plants; commonalities and differences to animal epithelial cells.

Kania U, Fendrych M, Friml J - Open Biol (2014)

Design of a specific screen for PIN polarity components. PIN2proteins localize to the apical side of epidermal cells in thegravitropic wild-type line. In the pin2 mutant,PIN2 proteins do not occur, provoking the agravitropic phenotype.PIN1-HA is mislocalized in the epidermis to the basal cell side inthe PIN2::PIN1-HA;pin2 line, resulting in anagravitropic phenotype. Mutations in the putative PIN polarityregulators (repp) are predicted to restore theapical localization of PIN1 and, hence, the gravitropicphenotype.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4043115&req=5

RSOB140017F3: Design of a specific screen for PIN polarity components. PIN2proteins localize to the apical side of epidermal cells in thegravitropic wild-type line. In the pin2 mutant,PIN2 proteins do not occur, provoking the agravitropic phenotype.PIN1-HA is mislocalized in the epidermis to the basal cell side inthe PIN2::PIN1-HA;pin2 line, resulting in anagravitropic phenotype. Mutations in the putative PIN polarityregulators (repp) are predicted to restore theapical localization of PIN1 and, hence, the gravitropicphenotype.
Mentions: Screening of mutants using the microscope by direct observation of the cellularPIN localization is very laborious and time consuming. To overcome thesedifficulties, it was necessary to translate the problem of polarity at thecellular level to a macroscopically visible phenotype that would be fast andeasy to screen. Examination of the gravitropic response of the mutagenizedtransgenic PIN2::PIN1-HA line in the pin2 mutant backgroundprovided the solution (figure 3).In wild-type plants, the apical localization of PIN2 in the root epidermisdirects the auxin flow from the root tip to the top parts of the root, enablingroot growth toward the gravity vector. In the PIN2::PIN1-HA line, the PIN1proteins localize predominantly at the basal side of epidermal cells and, thus,do not rescue the agravitropic phenotype of the pin2 mutant.Weak polarity mutants are mostly defective in PIN1 localization and exhibit abasal-to-apical polarity shift; hence, in polarity-defective mutants, the basalPIN1 proteins in the epidermis were hypothesized to be targeted to the apicaldomain, as macroscopically observed by the gravitropic growth restoration.Screening for mutants that respond to the gravity vector enabled theidentification of the repp3 mutant as a new candidate for thepolar PIN localization [134].FigureĀ 3.

Bottom Line: Although plant and animal cells use a similar core mechanism to deliver proteins to the plasma membrane, their different lifestyle, body organization and specific cell structures resulted in the acquisition of regulatory mechanisms that vary in the two kingdoms.In particular, cell polarity regulators do not seem to be conserved, because genes encoding key components are absent in plant genomes.In animals, much information is provided from the study of polarity in epithelial cells that exhibit basolateral and luminal apical polarities, separated by tight junctions.

View Article: PubMed Central - PubMed

Affiliation: Institute of Science and Technology Austria (IST Austria), 3400 Klosterneuburg, Austria.

ABSTRACT
Although plant and animal cells use a similar core mechanism to deliver proteins to the plasma membrane, their different lifestyle, body organization and specific cell structures resulted in the acquisition of regulatory mechanisms that vary in the two kingdoms. In particular, cell polarity regulators do not seem to be conserved, because genes encoding key components are absent in plant genomes. In plants, the broad knowledge on polarity derives from the study of auxin transporters, the PIN-FORMED proteins, in the model plant Arabidopsis thaliana. In animals, much information is provided from the study of polarity in epithelial cells that exhibit basolateral and luminal apical polarities, separated by tight junctions. In this review, we summarize the similarities and differences of the polarization mechanisms between plants and animals and survey the main genetic approaches that have been used to characterize new genes involved in polarity establishment in plants, including the frequently used forward and reverse genetics screens as well as a novel chemical genetics approach that is expected to overcome the limitation of classical genetics methods.

Show MeSH