The Coordinated KNR6–AGAP–ARF1 Complex Modulates Vegetative and Reproductive Traits by Participating in Vesicle Trafficking in Maize

The KERNEL NUMBER PER ROW6 (KNR6)-mediated phosphorylation of an adenosine diphosphate ribosylation factor (Arf) GTPase-activating protein (AGAP) forms a key regulatory module for the numbers of spikelets and kernels in the ear inflorescences of maize (Zea mays L.). However, the action mechanism of the KNR6–AGAP module remains poorly understood. Here, we characterized the AGAP-recruited complex and its roles in maize cellular physiology and agronomically important traits. AGAP and its two interacting Arf GTPase1 (ARF1) members preferentially localized to the Golgi apparatus. The loss-of-function AGAP mutant produced by CRISPR/Cas9 resulted in defective Golgi apparatus with thin and compact cisternae, together with delayed internalization and repressed vesicle agglomeration, leading to defective inflorescences and roots, and dwarfed plants with small leaves. The weak agap mutant was phenotypically similar to knr6, showing short ears with fewer kernels. AGAP interacted with KNR6, and a double mutant produced shorter inflorescence meristems and mature ears than the single agap and knr6 mutants. We hypothesized that the coordinated KNR6–AGAP–ARF1 complex modulates vegetative and reproductive traits by participating in vesicle trafficking in maize. Our findings provide a novel mechanistic insight into the regulation of inflorescence development, and ear length and kernel number, in maize.

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The LARGE2-APO1/APO2 regulatory module controls panicle size and grain number in rice

The Plant Cell ◽

10.1093/plcell/koab041 ◽

2021 ◽

Author(s):

Luojiang Huang ◽

Kai Hua ◽

Ran Xu ◽

Dali Zeng ◽

Ruci Wang ◽

...

Keyword(s):

Agronomic Traits ◽

Loss Of Function ◽

Grain Number ◽

Hect Domain ◽

Regulatory Module ◽

Promising Target ◽

Meristematic Activity ◽

Positive Regulators ◽

Genetic Mechanisms ◽

Biochemical Analyses

Abstract Panicle size and grain number are important agronomic traits and influence grain yield in rice (Oryza sativa), but the molecular and genetic mechanisms underlying panicle size and grain number control remain largely unknown in crops. Here we report that LARGE2 encodes a HECT-domain E3 ubiquitin ligase OsUPL2 and regulates panicle size and grain number in rice. The loss of function large2 mutants produce large panicles with increased grain number, wide grains and leaves, and thick culms. LARGE2 regulates panicle size and grain number by repressing meristematic activity. LARGE2 is highly expressed in young panicles and grains. Biochemical analyses show that LARGE2 physically associates with ABERRANT PANICLE ORGANIZATION1 (APO1) and APO2, two positive regulators of panicle size and grain number, and modulates their stabilities. Genetic analyses support that LARGE2 functions with APO1 and APO2 in a common pathway to regulate panicle size and grain number. These findings reveal a novel genetic and molecular mechanism of the LARGE2-APO1/APO2 module-mediated control of panicle size and grain number in rice, suggesting that this module is a promising target for improving panicle size and grain number in crops.

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Lessons from the study of plant mating systems for exploring the causes and consequences of inbreeding in marine invertebrates

Marine Biology ◽

10.1007/s00227-021-03838-7 ◽

2021 ◽

Vol 168 (3) ◽

Author(s):

Kevin C. Olsen ◽

Will H. Ryan ◽

Ellen T. Kosman ◽

Jose A. Moscoso ◽

Don R. Levitan ◽

...

Keyword(s):

Mating Systems ◽

Marine Invertebrates ◽

Reproductive Traits ◽

Theory And Practice ◽

Costs And Benefits ◽

Life History Variation ◽

Invertebrate Animals ◽

Plant Mating Systems ◽

Critical Insight ◽

Insight Into

AbstractMany benthic marine invertebrates resemble plants in being modular and either sessile or sedentary, and by relying on an external vector to disperse their gametes. These shared features, along with recent evidence of inbreeding in these taxa, suggest that theory and practice bearing on the evolutionary costs and benefits of inbreeding for plants could advance our understanding of the ecology and evolution of invertebrate animals. We describe how the theory for the evolution of inbreeding and outbreeding could apply to benthic invertebrates, identify and compare techniques used to quantify inbreeding in plants and animals, translate relevant botanical concepts and empirical patterns to their zoological equivalents, and articulate predictions for how inbreeding might be associated with major axes of variation in sessile and sedentary marine invertebrates. The theory of inbreeding and outbreeding provides critical insight into major patterns of life-history variation in plants and holds similar promise as a complementary perspective on the evolution of reproductive traits, lifespan, ecological strategies, and dispersal in marine invertebrates. Extending what we have learned from plants to marine invertebrates promises to broaden the general study of mating systems.

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An ethylene biosynthesis enzyme controls quantitative variation in maize ear length and kernel yield

Nature Communications ◽

10.1038/s41467-021-26123-z ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Qiang Ning ◽

Yinan Jian ◽

Yanfang Du ◽

Yunfu Li ◽

Xiaomeng Shen ◽

...

Keyword(s):

Gene Editing ◽

Ethylene Biosynthesis ◽

Flower Number ◽

Kernel Number ◽

Spikelet Number ◽

Inflorescence Development ◽

Grain Productivity ◽

Trait Locus ◽

Maize Gene ◽

Maize Ear

AbstractMaize ear size and kernel number differ among lines, however, little is known about the molecular basis of ear length and its impact on kernel number. Here, we characterize a quantitative trait locus, qEL7, to identify a maize gene controlling ear length, flower number and fertility. qEL7 encodes 1-aminocyclopropane-1- carboxylate oxidase2 (ACO2), a gene that functions in the final step of ethylene biosynthesis and is expressed in specific domains in developing inflorescences. Confirmation of qEL7 by gene editing of ZmACO2 leads to a reduction in ethylene production in developing ears, and promotes meristem and flower development, resulting in a ~13.4% increase in grain yield per ear in hybrids lines. Our findings suggest that ethylene serves as a key signal in inflorescence development, affecting spikelet number, floral fertility, ear length and kernel number, and also provide a tool to improve grain productivity by optimizing ethylene levels in maize or in other cereals.

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Converging physiological roles of the anthrax toxin receptors

F1000Research ◽

10.12688/f1000research.19423.1 ◽

2019 ◽

Vol 8 ◽

pp. 1415

Author(s):

Oksana A. Sergeeva ◽

F. Gisou van der Goot

Keyword(s):

Anthrax Toxin ◽

Loss Of Function ◽

Disease Symptoms ◽

Hyaline Fibromatosis Syndrome ◽

Anthrax Toxins ◽

The Difference ◽

Related Proteins ◽

Tumor Endothelial Marker 8 ◽

Insight Into ◽

Shed Light

The anthrax toxin receptors—capillary morphogenesis gene 2 (CMG2) and tumor endothelial marker 8 (TEM8)—were identified almost 20 years ago, although few studies have moved beyond their roles as receptors for the anthrax toxins to address their physiological functions. In the last few years, insight into their endogenous roles has come from two rare diseases: hyaline fibromatosis syndrome, caused by mutations in CMG2, and growth retardation, alopecia, pseudo-anodontia, and optic atrophy (GAPO) syndrome, caused by loss-of-function mutations in TEM8. Although CMG2 and TEM8 are highly homologous at the protein level, the difference in disease symptoms points to variations in the physiological roles of the two anthrax receptors. Here, we focus on the similarities between these receptors in their ability to regulate extracellular matrix homeostasis, angiogenesis, cell migration, and skin elasticity. In this way, we shed light on how mutations in these two related proteins cause such seemingly different diseases and we highlight the existing knowledge gaps that could form the focus of future studies.

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The D50N mutation and syndromic deafness: Altered Cx26 hemichannel properties caused by effects on the pore and intersubunit interactions

The Journal of General Physiology ◽

10.1085/jgp.201310962 ◽

2013 ◽

Vol 142 (1) ◽

pp. 3-22 ◽

Cited By ~ 49

Author(s):

Helmuth A. Sanchez ◽

Krista Villone ◽

Miduturu Srinivas ◽

Vytas K. Verselis

Keyword(s):

Sensorineural Deafness ◽

Gjb2 Gene ◽

Loss Of Function ◽

Impact Function ◽

Corneal Inflammation ◽

Extracellular Region ◽

Intersubunit Interactions ◽

Pore Lining ◽

Electrostatic Mechanism ◽

Insight Into

Mutations in the GJB2 gene, which encodes Cx26, are the most common cause of sensorineural deafness. In syndromic cases, such as keratitis-ichthyosis-deafness (KID) syndrome, in which deafness is accompanied by corneal inflammation and hyperkeratotic skin, aberrant hemichannel function has emerged as the leading contributing factor. We found that D50N, the most frequent mutation associated with KID syndrome, produces multiple aberrant hemichannel properties, including loss of inhibition by extracellular Ca2+, decreased unitary conductance, increased open hemichannel current rectification and voltage-shifted activation. We demonstrate that D50 is a pore-lining residue and that negative charge at this position strongly influences open hemichannel properties. Examination of two putative intersubunit interactions involving D50 suggested by the Cx26 crystal structure, K61–D50 and Q48–D50, showed no evidence of a K61–D50 interaction in hemichannels. However, our data suggest that Q48 and D50 interact and disruption of this interaction shifts hemichannel activation positive along the voltage axis. Additional shifts in activation by extracellular Ca2+ remained in the absence of a D50–Q48 interaction but required an Asp or Glu at position 50, suggesting a separate electrostatic mechanism that critically involves this position. In gap junction (GJ) channels, D50 substitutions produced loss of function, whereas K61 substitutions functioned as GJ channels but not as hemichannels. These data demonstrate that D50 exerts effects on Cx26 hemichannel and GJ channel function as a result of its dual role as a pore residue and a component of an intersubunit complex in the extracellular region of the hemichannel. Differences in the effects of substitutions in GJ channels and hemichannels suggest that perturbations in structure occur upon hemichannel docking that significantly impact function. Collectively, these data provide insight into Cx26 structure–function and the underlying bases for the phenotypes associated with KID syndrome patients carrying the D50N mutation.

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Membrane protein MHZ3 stabilizes OsEIN2 in rice by interacting with its Nramp-like domain

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1718377115 ◽

2018 ◽

Vol 115 (10) ◽

pp. 2520-2525 ◽

Cited By ~ 11

Author(s):

Biao Ma ◽

Yang Zhou ◽

Hui Chen ◽

Si-Jie He ◽

Yi-Hua Huang ◽

...

Keyword(s):

Membrane Protein ◽

Ethylene Signaling ◽

Loss Of Function ◽

Wild Type ◽

Protein Ubiquitination ◽

Ethylene Response ◽

Gene And Protein Expression ◽

Domain Loss ◽

Ethylene Insensitivity ◽

Insight Into

The phytohormone ethylene regulates many aspects of plant growth and development. EIN2 is the central regulator of ethylene signaling, and its turnover is crucial for triggering ethylene responses. Here, we identified a stabilizer of OsEIN2 through analysis of the rice ethylene-response mutant mhz3. Loss-of-function mutations lead to ethylene insensitivity in etiolated rice seedlings. MHZ3 encodes a previously uncharacterized membrane protein localized to the endoplasmic reticulum. Ethylene induces MHZ3 gene and protein expression. Genetically, MHZ3 acts at the OsEIN2 level in the signaling pathway. MHZ3 physically interacts with OsEIN2, and both the N- and C-termini of MHZ3 specifically associate with the OsEIN2 Nramp-like domain. Loss of mhz3 function reduces OsEIN2 abundance and attenuates ethylene-induced OsEIN2 accumulation, whereas MHZ3 overexpression elevates the abundance of both wild-type and mutated OsEIN2 proteins, suggesting that MHZ3 is required for proper accumulation of OsEIN2 protein. The association of MHZ3 with the Nramp-like domain is crucial for OsEIN2 accumulation, demonstrating the significance of the OsEIN2 transmembrane domains in ethylene signaling. Moreover, MHZ3 negatively modulates OsEIN2 ubiquitination, protecting OsEIN2 from proteasome-mediated degradation. Together, these results suggest that ethylene-induced MHZ3 stabilizes OsEIN2 likely by binding to its Nramp-like domain and impeding protein ubiquitination to facilitate ethylene signal transduction. Our findings provide insight into the mechanisms of ethylene signaling.

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Gene Expression in Developmental Stages of Schistosoma japonicum Provides Further Insight into the Importance of the Schistosome Insulin-Like Peptide

International Journal of Molecular Sciences ◽

10.3390/ijms20071565 ◽

2019 ◽

Vol 20 (7) ◽

pp. 1565 ◽

Cited By ~ 3

Author(s):

Xiaofeng Du ◽

Malcolm Jones ◽

Sujeevi Nawaratna ◽

Shiwanthi Ranasinghe ◽

Chunrong Xiong ◽

...

Keyword(s):

Schistosoma Japonicum ◽

Developmental Stages ◽

Insulin Receptors ◽

Glucose Consumption ◽

Adenosine Diphosphate ◽

Internal Cell ◽

Parasite Survival ◽

Survival And Growth ◽

Insight Into

We showed previously that the Schistosoma japonicum insulin-like peptide (SjILP) binds the worm insulin receptors, thereby, activating the parasite’s insulin pathway and emphasizing its important role in regulating uptake of glucose, a nutrient essential for parasite survival. Here we show that SjILP is differentially expressed in the schistosome life cycle and is especially highly transcribed in eggs, miracidia, and adult female worms. RNA inference was employed to knockdown SjILP in adults in vitro, with suppression confirmed by significantly reduced protein production, declined adenosine diphosphate levels, and reduction in glucose consumption. Immunolocalization showed that SjILP is located to lateral gland cells of mature intra-ovular miracidia in the schistosome egg, and is distributed on the ciliated epithelium and internal cell masses of newly transformed miracidia. In schistosomula, SjILP is present on the tegument in two antero-lateral points, indicating highly polarized expression during cercarial transformation. Analysis of serum from S. japonicum-infected mice by ELISA using a recombinant form of SjILP as an antigen revealed IgG immunoreactivity to this molecule at 7 weeks post-infection indicating it is likely secreted from mature eggs into the host circulation. These findings provide further insights on ILP function in schistosomes and its essential roles in parasite survival and growth in different development stages.

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TBC1D24-TLDc-related epilepsy exercise-induced dystonia: rescue by antioxidants in a disease model

Brain ◽

10.1093/brain/awz175 ◽

2019 ◽

Vol 142 (8) ◽

pp. 2319-2335 ◽

Cited By ~ 15

Author(s):

Kevin Lüthy ◽

Davide Mei ◽

Baptiste Fischer ◽

Maurizio De Fusco ◽

Jef Swerts ◽

...

Keyword(s):

Synaptic Vesicle ◽

Vesicle Trafficking ◽

Disease Model ◽

Stress Sensitivity ◽

Compound Heterozygous ◽

Missense Mutations ◽

Loss Of Function ◽

Rolandic Epilepsy ◽

Compound Heterozygous Mutations ◽

Exercise Induced

AbstractGenetic mutations in TBC1D24 have been associated with multiple phenotypes, with epilepsy being the main clinical manifestation. The TBC1D24 protein consists of the unique association of a Tre2/Bub2/Cdc16 (TBC) domain and a TBC/lysin motif domain/catalytic (TLDc) domain. More than 50 missense and loss-of-function mutations have been described and are spread over the entire protein. Through whole genome/exome sequencing we identified compound heterozygous mutations, R360H and G501R, within the TLDc domain, in an index family with a Rolandic epilepsy exercise-induced dystonia phenotype (http://omim.org/entry/608105). A 20-year long clinical follow-up revealed that epilepsy was self-limited in all three affected patients, but exercise-induced dystonia persisted into adulthood in two. Furthermore, we identified three additional sporadic paediatric patients with a remarkably similar phenotype, two of whom had compound heterozygous mutations consisting of an in-frame deletion I81_K84 and an A500V mutation, and the third carried T182M and G511R missense mutations, overall revealing that all six patients harbour a missense mutation in the subdomain of TLDc between residues 500 and 511. We solved the crystal structure of the conserved Drosophila TLDc domain. This allowed us to predict destabilizing effects of the G501R and G511R mutations and, to a lesser degree, of R360H and potentially A500V. Next, we characterized the functional consequences of a strong and a weak TLDc mutation (TBC1D24G501R and TBC1D24R360H) using Drosophila, where TBC1D24/Skywalker regulates synaptic vesicle trafficking. In a Drosophila model neuronally expressing human TBC1D24, we demonstrated that the TBC1D24G501R TLDc mutation causes activity-induced locomotion and synaptic vesicle trafficking defects, while TBC1D24R360H is benign. The neuronal phenotypes of the TBC1D24G501R mutation are consistent with exacerbated oxidative stress sensitivity, which is rescued by treating TBC1D24G501R mutant animals with antioxidants N-acetylcysteine amide or α-tocopherol as indicated by restored synaptic vesicle trafficking levels and sustained behavioural activity. Our data thus show that mutations in the TLDc domain of TBC1D24 cause Rolandic-type focal motor epilepsy and exercise-induced dystonia. The humanized TBC1D24G501R fly model exhibits sustained activity and vesicle transport defects. We propose that the TBC1D24/Sky TLDc domain is a reactive oxygen species sensor mediating synaptic vesicle trafficking rates that, when dysfunctional, causes a movement disorder in patients and flies. The TLDc and TBC domain mutations’ response to antioxidant treatment we observed in the animal model suggests a potential for combining antioxidant-based therapeutic approaches to TBC1D24-associated disorders with previously described lipid-altering strategies for TBC domain mutations.

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Recent Advances in Understanding the Genetic Architecture of Autism

Annual Review of Genomics and Human Genetics ◽

10.1146/annurev-genom-121219-082309 ◽

2020 ◽

Vol 21 (1) ◽

pp. 289-304 ◽

Cited By ~ 1

Author(s):

Caroline M. Dias ◽

Christopher A. Walsh

Keyword(s):

Genetic Architecture ◽

De Novo ◽

Clinical Care ◽

Copy Number Variants ◽

Autism Spectrum ◽

Loss Of Function ◽

Single Nucleotide Variants ◽

Single Nucleotide ◽

Recent Advances ◽

Insight Into

Recent advances in understanding the genetic architecture of autism spectrum disorder have allowed for unprecedented insight into its biological underpinnings. New studies have elucidated the contributions of a variety of forms of genetic variation to autism susceptibility. While the roles of de novo copy number variants and single-nucleotide variants—causing loss-of-function or missense changes—have been increasingly recognized and refined, mosaic single-nucleotide variants have been implicated more recently in some cases. Moreover, inherited variants (including common variants) and, more recently, rare recessive inherited variants have come into greater focus. Finally, noncoding variants—both inherited and de novo—have been implicated in the last few years. This work has revealed a convergence of diverse genetic drivers on common biological pathways and has highlighted the ongoing importance of increasing sample size and experimental innovation. Continuing to synthesize these genetic findings with functional and phenotypic evidence and translating these discoveries to clinical care remain considerable challenges for the field.

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