Shade avoidance responses are mediated by the ATHB-2 HD-zip protein, a negative regulator of gene expression

Development ◽  
1999 ◽  
Vol 126 (19) ◽  
pp. 4235-4245 ◽  
Author(s):  
C. Steindler ◽  
A. Matteucci ◽  
G. Sessa ◽  
T. Weimar ◽  
M. Ohgishi ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Proliferation ◽  
Cell Expansion ◽  
Lateral Root ◽  
Vascular System ◽  
Secondary Growth ◽  
Negative Regulator ◽  
Specific Cell ◽  
Shade Avoidance ◽  
Growth Responses

The ATHB-2 gene encoding an homeodomain-leucine zipper protein is rapidly and strongly induced by changes in the ratio of red to far-red light which naturally occur during the daytime under the canopy and induce in many plants the shade avoidance response. Here, we show that elevated ATHB-2 levels inhibit cotyledon expansion by restricting cell elongation in the cotyledon-length and -width direction. We also show that elevated ATHB-2 levels enhance longitudinal cell expansion in the hypocotyl. Interestingly, we found that ATHB-2-induced, as well as shade-induced, elongation of the hypocotyl is dependent on the auxin transport system. In the root and hypocotyl, elevated ATHB-2 levels also inhibit specific cell proliferation such as secondary growth of the vascular system and lateral root formation. Consistent with the key role of auxin in these processes, we found that auxin is able to rescue the ATHB-2 lateral root phenotype. We also show that reduced levels of ATHB-2 result in reciprocal phenotypes. Moreover, we demonstrate that ATHB-2 functions as a negative regulator of gene expression in a transient assay. Remarkably, the expression in transgenic plants of a derivative of ATHB-2 with the same DNA binding specificity but opposite regulatory properties results in a shift in the orientation of hypocotyl cell expansion toward radial expansion, and in an increase in hypocotyl secondary cell proliferation. A model of ATHB-2 function in the regulation of shade-induced growth responses is proposed.

scholarly journals Characterization of poplar growth-regulating factors and analysis of their function in leaf size control

2020 ◽  
Author(s):  
Jinnan Wang ◽  
Houjun Zhou ◽  
Yanqiu Zhao ◽  
Pengbo Sun ◽  
Fang Tang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cell Expansion ◽  
Populus Trichocarpa ◽  
Size Control ◽  
Leaf Size ◽  
Bioinformatic Analysis ◽  
Negative Regulator ◽  
Positive Regulators ◽  
Control Organ

Abstract Background: Growth-regulating factors (GRFs) are plant-specific transcription factors that control organ size. Nineteen GRF genes were identified in the Populus trichocarpa genome and one was reported to control leaf size by regulating cell expansion. In this study, we further characterize the roles of the other poplar GRFs in leaf size control in a similar manner.Results: The 19 poplar GRF genes were clustered into six groups according to their phylogenetic relationship with Arabidopsis GRFs. Bioinformatic analysis, degradome, and transient transcription assays showed that 18 poplar GRFs were regulated by miR396, with GRF12b the only exception. The functions of PagGRF6b (Pag, Populus alba × P. glandulosa), PagGRF7a, PagGRF12a, and PagGRF12b, representing three different groups, were investigated. The results show that PagGRF6b may have no function on leaf size control, while PagGRF7a functions as a negative regulator of leaf size by regulating cell expansion. By contrast, PagGRF12a and PagGRF12b may function as positive regulators of leaf size control by regulating both cell proliferation and expansion, primarily cell proliferation.Conclusions: The diversity of poplar GRFs in leaf size control may facilitate the specific, coordinated regulation of poplar leaf development through fine adjustment of cell proliferation and expansion.

scholarly journals Cyclosporin A inhibition of interleukin 2 gene expression, but not natural killer cell proliferation, after interferon induction in vivo.

1990 ◽  
Vol 171 (3) ◽  
pp. 745-762 ◽  
Author(s):  
M T Kasaian ◽  
C A Biron
Keyword(s):  
Gene Expression ◽  
Cell Proliferation ◽  
T Cell ◽  
Nk Cells ◽  
Cell Expansion ◽  
Nk Cell ◽  
Poly I:C ◽  
Low Density ◽  
Athymic Mice

The IFN inducer, poly(I:C), elicits acute NK cell blastogenesis and proliferation in vivo. The role of IL-2 in mediating this proliferation was investigated in the studies presented here. Blast NK cells were isolated from poly(I:C)-treated, T cell-deficient athymic mice. Dividing cells, incorporating [3H]thymidine, were enriched in the J11d- low density populations isolated from poly(I:C)-treated mice, and were characterized as NK by the following criteria: (a) they were eliminated by treatment with anti-AGM1 in vivo; and (b) they directly mediated lysis of NK-sensitive target cells in a single cell cytotoxicity assay with autoradiography. These poly(I:C)-induced blast NK cells were responsive to IL-2, but, when compared with in vivo activated T cells, responsiveness required 1,000-fold higher concentrations of the factor. The technique of in situ hybridization was used to evaluate induction of IL-2 gene expression after poly(I:C) treatment in vivo. Treatment of euthymic, athymic, and severe combined immunodeficient mice with poly(I:C) activated IL-2 gene expression in a small percentage of spleen leukocytes. The transcription-positive cells were enriched in low density cell populations. These findings demonstrate that IL-2 transcription occurs after IFN induction in vivo, and suggest that an endogenous source of IL-2 exists other than the mature T cell. To assess the IL-2 dependence of in vivo NK cell expansion, poly(I:C)-treated athymic mice were given cyclosporin A (CsA), an agent that regulates IL-2 production at the level of gene transcription. The drug resulted in an 85-100% reduction in the percentages of cells transcribing IL-2. In contrast, CsA administration did not block IFN-enhanced NK cell cytolytic activity, expansion of large granular lymphocyte numbers, or NK cell proliferation. These findings demonstrate that although the proliferation of blast NK cells can be supported by IL-2, IL-2 is not an important mediator of IFN-induced NK cell expansion. Moreover, they establish that the acute proliferation of NK cells in response to IFNs is CsA insensitive.

scholarly journals Differential Efficacy of 2 Vibrating Orthodontic Devices to Alter the Cellular Response in Osteoblasts, Fibroblasts, and Osteoclasts

Dose-Response ◽  
2018 ◽  
Vol 16 (3) ◽  
pp. 155932581879211 ◽  
Author(s):  
Stefan Judex ◽  
Suphannee Pongkitwitoon
Keyword(s):  
Gene Expression ◽  
Cell Proliferation ◽  
Vibration Frequency ◽  
Cellular Response ◽  
Alveolar Bone ◽  
Tooth Movement ◽  
Fibroblast Cell ◽  
Specific Cell ◽  
Periodontal Ligament Fibroblasts

Modalities that increase the rate of tooth movement have received considerable attention, but direct comparisons between devices are rare. Here, we contrasted 2 mechanical vibratory devices designed to directly transfer vibrations into alveolar bone as a means to influence bone remodeling. To this end, 3 cells types intimately involved in modulating tooth movements—osteoblasts, periodontal ligament fibroblasts, and osteoclasts—were subjected to in vitro vibrations at bout durations prescribed by the manufacturers. As quantified by an accelerometer, vibration frequency and peak accelerations were 400% and 70% greater in the VPro5 (Propel Orthodontics) than in the AcceleDent (OrthoAccel Technologies) device. Both devices caused increased cell proliferation and gene expression in osteoblasts and fibroblasts, but the response to VPro5 treatment was greater than for the AcceleDent. In contrast, the ability to increase osteoclast activity was device independent. These data present an important first step in determining how specific cell types important for facilitating tooth movement respond to different vibration profiles. The device that engendered a higher vibration frequency and larger acceleration (VPro5) was superior in stimulating osteoblast and fibroblast cell proliferation/gene expression, although the duration of each treatment bout was 75% shorter than for the AcceleDent.

scholarly journals Growth of the Fucus embryo: insights into wall-mediated cell expansion through mechanics and transcriptomics

2020 ◽  
Author(s):  
Marina Linardić ◽  
Shawn J. Cokus ◽  
Matteo Pellegrini ◽  
Siobhan A. Braybrook
Keyword(s):  
Gene Expression ◽  
Cell Proliferation ◽  
Cell Wall ◽  
Differential Gene Expression ◽  
Brown Algae ◽  
Cell Expansion ◽  
Algal Cell ◽  
Data Set ◽  
Wall Stiffness ◽  
Differential Gene

AbstractMorphogenesis in walled organisms represents a highly controlled process that involves cell proliferation and expansion; cell growth is regulated through changes in the structure and mechanics of the cells’ walls. Despite taking different evolutionary paths, land plants and some brown algae exhibit developmental and morphological similarities; however, the role of the algal cell wall in morphogenesis remains heavily underexplored. Cell expansion in plants is hypothesized to involve modifications of hemicellulose linkages and pectin gelation in the cell wall. Little is known about the wall-based control of cell expansion in brown algae; however, the algal analog to pectin, alginate, exhibits different gelation depending on its biochemistry. Here we show that cell wall mechanics and alginate biochemistry are correlated with cell expansion versus proliferation in the developing Fucus serratus embryo. In the elongating cells of the embryo rhizoid, we found a reduced cell wall stiffness and lower amounts of ‘stiffer’ alginate epitopes. In comparison, the early embryo thallus was shown to undergo cleavage-type cell proliferation, without expansion, and this was correlated with higher amounts of ‘stiff’ alginate epitopes and increased wall stiffness. An embryo development RNAseq dataset was generated to characterize differential gene expression during development. This data set allowed for identification of many enriched GO functions through developmental time. In addition, the transcriptome allowed for the identification of cell-wall related genes whose differential expression may underlie our observed growth phenotypes. We propose that differential gene expression of genes involved in alginate stiffness are strong candidates underlying differential wall stiffness and cell elongation in the developing Fucus embryo. Our results show that wall-driven cellular expansion mechanisms in brown algae are similar to those observed in plants. In addition, our data show that cleavage-type cell proliferation exists in brown algae similar to that seen in plant and animal systems indicating a possible conserved developmental phenomenon across the branches of multicellular life.

scholarly journals Characterization of Poplar Growth-Regulating Factors and Analysis of Their Function in Leaf Size Control

2020 ◽  
Author(s):  
Jinnan Wang ◽  
Houjun Zhou ◽  
Yanqiu Zhao ◽  
Pengbo Sun ◽  
Fang Tang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cell Expansion ◽  
Populus Trichocarpa ◽  
Size Control ◽  
Leaf Size ◽  
Bioinformatic Analysis ◽  
Negative Regulator ◽  
Positive Regulators ◽  
Control Organ

Abstract Background: Growth-regulating factors (GRFs) are plant-specific transcription factors that control organ size. Nineteen GRF genes were identified in the Populus trichocarpa genome and one was reported to control leaf size by regulating cell expansion. In this study, we further characterize the roles of the other poplar GRFs in leaf size control in a similar manner. Results: The 19 poplar GRF genes were clustered into six groups according to their phylogenetic relationship with Arabidopsis GRFs. Bioinformatic analysis, degradome, and transient transcription assays showed that 18 poplar GRFs were regulated by miR396, with GRF12b the only exception. The functions of PagGRF6b (Pag, Populus alba × P. glandulosa), PagGRF7a, PagGRF12a, and PagGRF12b, representing three different groups, were investigated and the results show that they have different roles in leaf size control. PagGRF6b has no function, while PagGRF7a functions as a negative regulator of leaf size by regulating cell expansion. By contrast, PagGRF12a and PagGRF12b function as positive regulators of leaf size control by regulating both cell proliferation and expansion, primarily cell proliferation. Conclusions: The diversity of poplar GRFs in leaf size control may facilitate the specific, coordinated regulation of poplar leaf development through fine adjustment of cell proliferation and expansion.

scholarly journals Characterization of poplar growth-regulating factors and analysis of their function in leaf size control

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Jinnan Wang ◽  
Houjun Zhou ◽  
Yanqiu Zhao ◽  
Pengbo Sun ◽  
Fang Tang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cell Expansion ◽  
Populus Trichocarpa ◽  
Size Control ◽  
Leaf Size ◽  
Bioinformatic Analysis ◽  
Negative Regulator ◽  
Positive Regulators ◽  
Control Organ

Abstract Background Growth-regulating factors (GRFs) are plant-specific transcription factors that control organ size. Nineteen GRF genes were identified in the Populus trichocarpa genome and one was reported to control leaf size mainly by regulating cell expansion. In this study, we further characterize the roles of the other poplar GRFs in leaf size control in a similar manner. Results The 19 poplar GRF genes were clustered into six groups according to their phylogenetic relationship with Arabidopsis GRFs. Bioinformatic analysis, degradome, and transient transcription assays showed that 18 poplar GRFs were regulated by miR396, with GRF12b the only exception. The functions of PagGRF6b (Pag, Populus alba × P. glandulosa), PagGRF7a, PagGRF12a, and PagGRF12b, representing three different groups, were investigated. The results show that PagGRF6b may have no function on leaf size control, while PagGRF7a functions as a negative regulator of leaf size by regulating cell expansion. By contrast, PagGRF12a and PagGRF12b may function as positive regulators of leaf size control by regulating both cell proliferation and expansion, primarily cell proliferation. Conclusions The diversity of poplar GRFs in leaf size control may facilitate the specific, coordinated regulation of poplar leaf development through fine adjustment of cell proliferation and expansion.

scholarly journals Characterization of poplar growth-regulating factors and analysis of their function in leaf size control

2020 ◽  
Author(s):  
Jinnan Wang ◽  
Houjun Zhou ◽  
Yanqiu Zhao ◽  
Pengbo Sun ◽  
Fang Tang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cell Expansion ◽  
Populus Trichocarpa ◽  
Size Control ◽  
Leaf Size ◽  
Bioinformatic Analysis ◽  
Negative Regulator ◽  
Positive Regulators ◽  
Control Organ

Abstract Background: Growth-regulating factors (GRFs) are plant-specific transcription factors that control organ size. Nineteen GRF genes were identified in the Populus trichocarpa genome and one was reported to control leaf size by regulating cell expansion. In this study, we further characterize the roles of the other poplar GRFs in leaf size control in a similar manner. Results: The 19 poplar GRF genes were clustered into six groups according to their phylogenetic relationship with Arabidopsis GRFs. Bioinformatic analysis, degradome, and transient transcription assays showed that 18 poplar GRFs were regulated by miR396, with GRF12b the only exception. The functions of PagGRF6b (Pag, Populus alba × P. glandulosa), PagGRF7a, PagGRF12a, and PagGRF12b, representing three different groups, were investigated. The results show that PagGRF6b may have no function on leaf size control, while PagGRF7a functions as a negative regulator of leaf size by regulating cell expansion. By contrast, PagGRF12a and PagGRF12b may function as positive regulators of leaf size control by regulating both cell proliferation and expansion, primarily cell proliferation. Conclusions: The diversity of poplar GRFs in leaf size control may facilitate the specific, coordinated regulation of poplar leaf development through fine adjustment of cell proliferation and expansion.

scholarly journals Characterization of poplar growth-regulating factors and analysis of their function in leaf size control

2020 ◽  
Author(s):  
Jinnan Wang ◽  
Houjun Zhou ◽  
Yanqiu Zhao ◽  
Pengbo Sun ◽  
Fang Tang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cell Expansion ◽  
Populus Trichocarpa ◽  
Size Control ◽  
Leaf Size ◽  
Bioinformatic Analysis ◽  
Negative Regulator ◽  
Positive Regulators ◽  
Control Organ

Abstract Background: Growth-regulating factors (GRFs) are plant-specific transcription factors that control organ size. Nineteen GRF genes were identified in the Populus trichocarpa genome and one was reported to control leaf size by regulating cell expansion. In this study, we further characterize the roles of the other poplar GRFs in leaf size control in a similar manner.Results: The 19 poplar GRF genes were clustered into six groups according to their phylogenetic relationship with Arabidopsis GRFs. Bioinformatic analysis, degradome, and transient transcription assays showed that 18 poplar GRFs were regulated by miR396, with GRF12b the only exception. The functions of PagGRF6b (Pag, Populus alba × P. glandulosa), PagGRF7a, PagGRF12a, and PagGRF12b, representing three different groups, were investigated. The results show that PagGRF6b may have no function on leaf size control, while PagGRF7a functions as a negative regulator of leaf size by regulating cell expansion. By contrast, PagGRF12a and PagGRF12b may function as positive regulators of leaf size control by regulating both cell proliferation and expansion, primarily cell proliferation.Conclusions: The diversity of poplar GRFs in leaf size control may facilitate the specific, coordinated regulation of poplar leaf development through fine adjustment of cell proliferation and expansion.

scholarly journals Characterization of poplar growth-regulating factors and analysis of their function in leaf size control

2020 ◽  
Author(s):  
Jinnan Wang ◽  
Houjun Zhou ◽  
Yanqiu Zhao ◽  
Pengbo Sun ◽  
Fang Tang ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Cell Expansion ◽  
Populus Trichocarpa ◽  
Size Control ◽  
Leaf Size ◽  
Bioinformatic Analysis ◽  
Negative Regulator ◽  
Positive Regulators ◽  
Control Organ

Abstract Background: Growth-regulating factors (GRFs) are plant-specific transcription factors that control organ size. Nineteen GRF genes were identified in the Populus trichocarpa genome and one was reported to control leaf size by regulating cell expansion. In this study, we further characterize the roles of the other poplar GRFs in leaf size control in a similar manner. Results: The 19 poplar GRF genes were clustered into six groups according to their phylogenetic relationship with Arabidopsis GRFs. Bioinformatic analysis, degradome, and transient transcription assays showed that 18 poplar GRFs were regulated by miR396, with GRF12b the only exception. The functions of PagGRF6b (Pag, Populus alba × P. glandulosa), PagGRF7a, PagGRF12a, and PagGRF12b, representing three different groups, were investigated. The results show that PagGRF6b may have no function on leaf size control, while PagGRF7a functions as a negative regulator of leaf size by regulating cell expansion. By contrast, PagGRF12a and PagGRF12b may function as positive regulators of leaf size control by regulating both cell proliferation and expansion, primarily cell proliferation. Conclusions: The diversity of poplar GRFs in leaf size control may facilitate the specific, coordinated regulation of poplar leaf development through fine adjustment of cell proliferation and expansion.

ACE INHIBITION ATTENUATES RENAL PDGF GENE EXPRESSION AND CELL PROLIFERATION IN SUBTOTAL NEPHRECTOMY

Nephrology ◽  
2000 ◽  
Vol 5 (3) ◽  
pp. A104-A104
Author(s):  
Jandeleit‐Dahm K ◽  
Wu Ll ◽  
Johnson Rj ◽  
Cox Aj ◽  
Kelly Dj ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Proliferation ◽  
Ace Inhibition ◽  
Subtotal Nephrectomy
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