Hussain, H.; Ziegler, J.; Hause, G.; Wohlrab, J.; Neubert, R. H. H. Quantitative Analysis of Free Amino Acids and Urea
Derived from Isolated Corneocytes of Healthy Young, Healthy Aged, and
Diseased Skin Skin Pharmacol Physiol 32, 94-100, (2019) DOI: 10.1159/000495992
Background/Aims: Free amino acids (FAAs) and
urea, present inside the corneocytes, can be important indicators of
skin condition. However, due to the lack of a standard extraction
protocol for FAAs from corneocytes, conflicting research results have
been reported. Therefore, the purpose of this study was (1) to
standardize the extraction protocol and (2) to investigate FAA profiles
in healthy young and healthy old volunteers, as well as in psoriasis and
atopic dermatitis patients. Methods: Skin samples were collected from
four groups (healthy young, healthy old, and psoriasis and atopic
dermatitis patients) with 5 volunteers per group. Corneocytes were
isolated and examined microscopically. FAAs and urea were extracted from
the isolated corneocytes, and their amounts were quantified using
LC-ESI/MS/MS (after derivatization with Fmoc-Cl) and colorimetric
methods, respectively. Results: The micrographs of the corneocytes
showed no morphological features attributable to age or disease
conditions. The highest and lowest concentrations of total FAAs and urea
were observed in the healthy old group and the healthy young group,
respectively. Unlike the other FAAs and urea, citrulline was found at a
higher level in the healthy young group than in the disease groups.
Conclusion: This study suggests that the levels of FAAs and urea in the
skin are affected by age and skin conditions (healthy/diseased).
However, further studies are needed to show the effects of different
skin conditions on the levels of FAAs and urea.
Naumann, C.; Müller, J.; Sakhonwasee, S.; Wieghaus, A.; Hause, G.; Heisters, M.; Bürstenbinder, K.; Abel, S. The Local Phosphate Deficiency Response Activates Endoplasmic Reticulum Stress-Dependent Autophagy Plant Physiol 179, 460-476, (2019) DOI: 10.1104/pp.18.01379
Inorganic phosphate (Pi) is often a limiting plant
nutrient. In members of the Brassicaceae family, such as Arabidopsis
(Arabidopsis thaliana), Pi deprivation reshapes root system architecture
to favor topsoil foraging. It does so by inhibiting primary root
extension and stimulating lateral root formation. Root growth inhibition
from phosphate (Pi) deficiency is triggered by iron-stimulated,
apoplastic reactive oxygen species generation and cell wall
modifications, which impair cell-to-cell communication and meristem
maintenance. These processes require LOW PHOSPHATE RESPONSE1 (LPR1), a
cell wall-targeted ferroxidase, and PHOSPHATE DEFICIENCY RESPONSE2
(PDR2), the single endoplasmic reticulum (ER)-resident P5-type ATPase
(AtP5A), which is thought to control LPR1 secretion or activity.
Autophagy is a conserved process involving the vacuolar degradation of
cellular components. While the function of autophagy is well established
under nutrient starvation (C, N, or S), it remains to be explored under
Pi deprivation. Because AtP5A/PDR2 likely functions in the ER stress
response, we analyzed the effect of Pi limitation on autophagy. Our
comparative study of mutants defective in the local Pi deficiency
response, ER stress response, and autophagy demonstrated that ER
stress-dependent autophagy is rapidly activated as part of the
developmental root response to Pi limitation and requires the genetic
PDR2-LPR1 module. We conclude that Pi-dependent activation of autophagy
in the root apex is a consequence of local Pi sensing and the associated
ER stress response, rather than a means for systemic recycling of the
Bürstenbinder, K.; Möller, B.; Plötner; R.; Stamm, G.; Hause, G.; Mitra, D.; Abel, S. The IQD family of calmodulin-binding proteins links calcium signaling to microtubules, membrane subdomains, and the nucleus. Plant Physiol 173, 1692-1708, (2017) DOI: 10.1104/pp.16.01743
Calcium (Ca2+) signaling and dynamic reorganization of the cytoskeleton are essential processes for the coordination and control of plant cell shape and cell growth. Calmodulin (CaM) and closely related CaM-like polypeptides (CML) are principal sensors of Ca2+ signals. CaM/CMLs decode and relay information encrypted by the second messenger via differential interactions with a wide spectrum of targets to modulate their diverse biochemical activities. The plant-specific IQ67-DOMAIN (IQD) family emerged as the possibly largest class of CaM interacting proteins with undefined molecular functions and biological roles. Here, we show that the 33 members of the IQD family in Arabidopsis thaliana differentially localize, using GFP-tagged proteins, to multiple and distinct subcellular sites, including microtubule (MT) arrays, plasma membrane microdomains, and nuclear compartments. Intriguingly, the various IQD-specific localization patterns coincide with the subcellular patterns of IQD-dependent recruitment of CaM, suggesting that the diverse IQD members sequester Ca2+-CaM signaling modules to specific subcellular sites for precise regulation of Ca2+-dependent processes. Because MT localization is a hallmark of most IQD family members, we quantitatively analyzed GFP-labeled MT arrays in tobacco cells transiently expressing GFP-IQD fusions and observed IQD-specific MT patterns, which point to a role of IQDs in MT organization and dynamics. Indeed, stable overexpression of select IQD proteins in Arabidopsis altered cellular MT orientation, cell shape, and organ morphology. Because IQDs share biochemical properties with scaffold proteins, we propose that IQD families provide an assortment of platform proteins for integrating CaM-dependent Ca2+ signaling at multiple cellular sites to regulate cell function, shape, and growth.
Drost, H.-G.; Bellstädt, J.; Ó'Maoiléidigh, D. S.; Silva, A. T.; Gabel, A.; Weinholdt, C.; Ryan, P. T.; Dekkers, B. J. W.; Bentsink, L.; Hilhorst, H. W. M.; Ligterink, W.; Wellmer, F.; Grosse, I.; Quint, M. Post-embryonic Hourglass Patterns Mark Ontogenetic Transitions in Plant Development Mol Biol Evol 33, 1158-1163, (2016) DOI: 10.1093/molbev/msw039
The historic developmental hourglass concept depicts the convergence of animal embryos to a common form during the phylotypic period. Recently, it has been shown that a transcriptomic hourglass is associated with this morphological pattern, consistent with the idea of underlying selective constraints due to intense molecular interactions during body plan establishment. Although plants do not exhibit a morphological hourglass during embryogenesis, a transcriptomic hourglass has nevertheless been identified in the model plant Arabidopsis thaliana. Here, we investigated whether plant hourglass patterns are also found postembryonically. We found that the two main phase changes during the life cycle of Arabidopsis, from embryonic to vegetative and from vegetative to reproductive development, are associated with transcriptomic hourglass patterns. In contrast, flower development, a process dominated by organ formation, is not. This suggests that plant hourglass patterns are decoupled from organogenesis and body plan establishment. Instead, they may reflect general transitions through organizational checkpoints.
Müller, J.; Toev, T.; Heisters, M.; Teller, J.; Moore, K. L.; Hause, G.; Dinesh, D. C.; Bürstenbinder, K.; Abel, S. Iron-Dependent Callose Deposition Adjusts Root Meristem Maintenance to Phosphate Availability Devel Cell 33, 216–230, (2015) DOI: 10.1016/j.devcel.2015.02.007
Plant root development is informed by numerous edaphic cues. Phosphate (Pi) availability impacts the root system architecture by adjusting meristem activity. However, the sensory mechanisms monitoring external Pi status are elusive. Two functionally interacting Arabidopsis genes, LPR1 (ferroxidase) and PDR2 (P5-type ATPase), are key players in root Pi sensing, which is modified by iron (Fe) availability. We show that the LPR1-PDR2 module facilitates, upon Pi limitation, cell-specific apoplastic Fe and callose deposition in the meristem and elongation zone of primary roots. Expression of cell-wall-targeted LPR1 determines the sites of Fe accumulation as well as callose production, which interferes with symplastic communication in the stem cell niche, as demonstrated by impaired SHORT-ROOT movement. Antagonistic interactions of Pi and Fe availability control primary root growth via meristem-specific callose formation, likely triggered by LPR1-dependent redox signaling. Our results link callose-regulated cell-to-cell signaling in root meristems to the perception of an abiotic cue
Ryan,P. T.; Ó’Maoiléidigh, D. S.; Drost, H.-G.; Kwaśniewska, D.; Gabel, A.; Grosse, I.; Graciet, E.; Quint, M.; Wellmer, F. Patterns of gene expression during Arabidopsis flower development from the time of initiation to maturation BMC Genomics 16, 488 , (2015) DOI: 10.1186/s12864-015-1699-6
Background:The formation of flowers is one of the main model systems to elucidate the molecular mechanisms that control developmental processes in plants. Although several studies have explored gene expression during flower development in the model plant Arabidopsis thalianaon a genome-wide scale, a continuous series of expression data from the earliest floral stages until maturation has been lacking. Here, we used a floral induction system to closethis information gap and to generate a reference dataset for stage-specific gene expression during flower formation.Results:Using a floral induction system, we collected floral buds at 14 different stages from the time of initiation until maturation. Using whole-genome microarray analysis, we identified 7,405 genes that exhibit rapid expression changes during flower development. These genes comprise many known floral regulators and we found that the expression profiles for these regulators match their known expression patterns, thus validating the dataset. We analyzed groups ofco-expressed genes for over-represented cellular and developmental functions through Gene Ontology analysis and found that they could be assigned specific patterns of activities, which are in agreement with the progression of flower development. Furthermore, by mapping binding sites of floral organ identity factors onto our dataset, we were able to identify gene groups that are likely predominantly under control of these transcriptional regulators. We furtherfound that the distribution of paralogs among groups of co-expressed genes varies considerably, with genes expressed predominantly at early and intermediate stages of flower development showing the highest proportion of such genes.Conclusions:Our results highlight and describe the dynamic expression changes undergone by a large numberof genes during flower development. They further provide a comprehensive reference dataset for temporal gene expression during flower formation and we demonstrate that it can be used to integrate data from other genomics approaches such as genome-wide localization studies of transcription factor binding sites.
Drost, H.-G.; Gabel, A.; Grosse, I.; Quint, M. Evidence for Active Maintenance of Phylotranscriptomic Hourglass Patterns in Animal and Plant Embryogenesis Mol Biol Evol 32, 1221-1231, (2015) DOI: 10.1093/molbev/msv012
The developmental hourglass model has been used to describe the morphological transitions of related species throughout embryogenesis. Recently, quantifiable approaches combining transcriptomic and evolutionary information provided novel evidence for the presence of a phylotranscriptomic hourglass pattern across kingdoms. As its biological function is unknown it remains speculative whether this pattern is functional or merely represents a nonfunctional evolutionary relic. The latter would seriously hamper future experimental approaches designed to test hypotheses regarding its function. Here, we address this question by generating transcriptome divergence index (TDI) profiles across embryogenesis of Danio rerio, Drosophila melanogaster, and Arabidopsis thaliana. To enable meaningful evaluation of the resulting patterns, we develop a statistical test that specifically assesses potential hourglass patterns. Based on this objective measure we find that two of these profiles follow a statistically significant hourglass pattern with the most conserved transcriptomes in the phylotypic periods. As the TDI considers only recent evolutionary signals, this indicates that the phylotranscriptomic hourglass pattern is not a rudiment but possibly actively maintained, implicating the existence of some linked biological function associated with embryogenesis in extant species.
Drost, H.-G.; Bellstädt, J.; Ó'Maoiléidigh, D. S.; Silva, A. T.; Gabel, A.; Weinholdt, C.; Ryan, P. T.; Dekkers, B. J. W.; Bentsink, L.; Hilhorst, H. W. M.; Ligterink, W.; Wellmer, F.; Grosse, I.; Quint, M. Post-embryonic hourglass patterns mark ontogenetic transitions in plant development bioRxiv (2015) DOI: 10.1101/035527
The historic developmental hourglass concept depicts the convergence of
animal embryos to a common form during the phylotypic period. Recently,
it has been shown that a transcriptomic hourglass is associated with
this morphological pattern, consistent with the idea of underlying
selective constraints due to intense molecular interactions during body
plan establishment. Although plants do not exhibit a morphological
hourglass during embryogenesis, a transcriptomic hourglass has
nevertheless been identified in the model plant Arabidopsis thaliana.
Here, we investigated whether plant hourglass patterns are also found
post-embryonically. We found that the two main phase changes during the
life cycle of Arabidopsis, from embryonic to vegetative and from
vegetative to reproductive development, are associated with
transcriptomic hourglass patterns. In contrast, flower development, a
process dominated by organ formation, is not. This suggests that plant
hourglass patterns are decoupled from organogenesis and body plan
establishment. Instead, they may reflect general transitions through
Dekkers, B.J.W.; Pearce, S.; van Bolderen-Veldkamp, R.P.; Marshall, A.; Widera, P.; Gilbert, J.; Drost, H.-G.; Basseli, G.W.; Müller, K.; King, J.R.; Wood, A.T.A.; Grosse, I.; Quint, M.; Krasnogor, N.; Leubner-Metzger, G.; Holdsworth, M.J. & Bentsink, L. Transcriptional Dynamics of Two Seed Compartments with Opposing Roles in Arabidopsis Seed Germination Plant Physiol 163, 205-215, (2013) DOI: 10.1104/pp.113.223511
Seed germination is a critical stage in the plant life cycle and the first step toward successful plant establishment. Therefore, understandinggermination is of important ecological and agronomical relevance. Previous research revealed that different seed compartments (testa,endosperm, and embryo) control germination, but little is known about the underlying spatial and temporal transcriptome changes thatlead to seed germination. We analyzed genome-wide expression in germinating Arabidopsis (Arabidopsis thaliana) seedswith both temporaland spatial detail and provide Web-accessible visualizations of the data reported (vseed.nottingham.ac.uk). We show the potential of this highresolutiondata set for the construction ofmeaningful coexpression networks, which provide insight into the genetic control of germination.The data set reveals two transcriptional phases during germination that are separated by testa rupture. The first phase is marked by largetranscriptome changes as the seed switches from a dry, quiescent state to a hydrated and active state. At the end of this first transcriptionalphase, the number of differentially expressed genes between consecutive time points drops. This increases again at testa rupture, the start ofthe second transcriptional phase. Transcriptome data indicate a role for mechano-induced signaling at this stage and subsequently highlightthe fates of the endosperm and radicle: senescence and growth, respectively. Finally, using a phylotranscriptomic approach, we show thatexpression levels of evolutionarily young genes drop during the first transcriptional phase and increase during the second phase.Evolutionarily old genes show an opposite pattern, suggesting a more conserved transcriptome prior to the completion of germination.
Goetz, S.; Hellwege, A.; Stenzel, I.; Kutter, C.; Hauptmann, V.; Forner, S.; McCaig, B.; Hause, G.; Miersch, O.; Wasternack, C.; Hause, B. Role of cis-12-oxo-phytodienoic acid in tomato embryo development. Plant Physiol 158, 1715-1727, (2012) DOI: 10.1104/pp.111.192658
Oxylipins including jasmonates are signaling compounds in plant growth, development, and responses to biotic and abiotic stresses. In Arabidopsis (Arabidopsis thaliana) most mutants affected in jasmonic acid (JA) biosynthesis and signaling are male sterile, whereas the JA-insensitive tomato (Solanum lycopersicum) mutant jai1 is female sterile. The diminished seed formation in jai1 together with the ovule-specific accumulation of the JA biosynthesis enzyme allene oxide cyclase (AOC), which correlates with elevated levels of JAs, suggest a role of oxylipins in tomato flower/seed development. Here, we show that 35S::SlAOC-RNAi lines with strongly reduced AOC in ovules exhibited reduced seed set similarly to the jai1 plants. Investigation of embryo development of wild-type tomato plants showed preferential occurrence of AOC promoter activity and AOC protein accumulation in the developing seed coat and the embryo, whereas 12-oxo-phytodienoic acid (OPDA) was the dominant oxylipin occurring nearly exclusively in the seed coat tissues. The OPDA- and JA-deficient mutant spr2 was delayed in embryo development and showed an increased programmed cell death in the developing seed coat and endosperm. In contrast, the mutant acx1a, which accumulates preferentially OPDA and residual amount of JA, developed embryos similar to the wild type, suggesting a role of OPDA in embryo development. Activity of the residual amount of JA in the acx1a mutant is highly improbable since the known reproductive phenotype of the JA-insensitive mutant jai1 could be rescued by wound-induced formation of OPDA. These data suggest a role of OPDA or an OPDA-related compound for proper embryo development possibly by regulating carbohydrate supply and detoxification.