1
|
Ruan J, Yin Z, Yi P. Effects of fluorescent tags and activity status on the membrane localization of ROP GTPases. PLANT SIGNALING & BEHAVIOR 2024; 19:2306790. [PMID: 38270144 PMCID: PMC10813580 DOI: 10.1080/15592324.2024.2306790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Accepted: 01/08/2024] [Indexed: 01/26/2024]
Abstract
Plant-specific Rho-type GTPases (ROPs) are master regulators of cell polarity and development. Over the past 30 years, their localization and dynamics have been largely examined with fluorescent proteins fused at the amino terminus without investigating their impact on protein function. The moss Physcomitrium patens genome encodes four rop genes. In this study, we introduce a fluorescent tag at the endogenous amino terminus of ROP4 in wild-type and rop1,2,3 triple mutant via homologous recombination and demonstrate that the fluorescent tag severely impairs ROP4 function and inhibits its localization on the plasma membrane. This phenotype is exacerbated in mutants lacking ROP-related GTPase-activating proteins. By comparing the localization of nonfunctional and functional ROP4 fusion reporters, we provide insight into the mechanism that governs the membrane association of ROPs.
Collapse
Affiliation(s)
- Jingtong Ruan
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan, P. R. China
| | - Zihan Yin
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan, P. R. China
| | - Peishan Yi
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, Sichuan, P. R. China
| |
Collapse
|
2
|
Bement WM, Goryachev AB, Miller AL, von Dassow G. Patterning of the cell cortex by Rho GTPases. Nat Rev Mol Cell Biol 2024; 25:290-308. [PMID: 38172611 DOI: 10.1038/s41580-023-00682-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2023] [Indexed: 01/05/2024]
Abstract
The Rho GTPases - RHOA, RAC1 and CDC42 - are small GTP binding proteins that regulate basic biological processes such as cell locomotion, cell division and morphogenesis by promoting cytoskeleton-based changes in the cell cortex. This regulation results from active (GTP-bound) Rho GTPases stimulating target proteins that, in turn, promote actin assembly and myosin 2-based contraction to organize the cortex. This basic regulatory scheme, well supported by in vitro studies, led to the natural assumption that Rho GTPases function in vivo in an essentially linear matter, with a given process being initiated by GTPase activation and terminated by GTPase inactivation. However, a growing body of evidence based on live cell imaging, modelling and experimental manipulation indicates that Rho GTPase activation and inactivation are often tightly coupled in space and time via signalling circuits and networks based on positive and negative feedback. In this Review, we present and discuss this evidence, and we address one of the fundamental consequences of coupled activation and inactivation: the ability of the Rho GTPases to self-organize, that is, direct their own transition from states of low order to states of high order. We discuss how Rho GTPase self-organization results in the formation of diverse spatiotemporal cortical patterns such as static clusters, oscillatory pulses, travelling wave trains and ring-like waves. Finally, we discuss the advantages of Rho GTPase self-organization and pattern formation for cell function.
Collapse
Affiliation(s)
- William M Bement
- Center for Quantitative Cell Imaging, Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI, USA.
| | - Andrew B Goryachev
- Center for Engineering Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
| | - Ann L Miller
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
| | | |
Collapse
|
3
|
Deinum EE, Jacobs B. Rho of Plants patterning: linking mathematical models and molecular diversity. JOURNAL OF EXPERIMENTAL BOTANY 2024; 75:1274-1288. [PMID: 37962515 PMCID: PMC10901209 DOI: 10.1093/jxb/erad447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Accepted: 11/08/2023] [Indexed: 11/15/2023]
Abstract
ROPs (Rho of Plants) are plant specific small GTPases involved in many membrane patterning processes and play important roles in the establishment and communication of cell polarity. These small GTPases can produce a wide variety of patterns, ranging from a single cluster in tip-growing root hairs and pollen tubes to an oriented stripe pattern controlling protoxylem cell wall deposition. For an understanding of what controls these various patterns, models are indispensable. Consequently, many modelling studies on small GTPase patterning exist, often focusing on yeast or animal cells. Multiple patterns occurring in plants, however, require the stable co-existence of multiple active ROP clusters, which does not occur with the most common yeast/animal models. The possibility of such patterns critically depends on the precise model formulation. Additionally, different small GTPases are usually treated interchangeably in models, even though plants possess two types of ROPs with distinct molecular properties, one of which is unique to plants. Furthermore, the shape and even the type of ROP patterns may be affected by the cortical cytoskeleton, and cortex composition and anisotropy differ dramatically between plants and animals. Here, we review insights into ROP patterning from modelling efforts across kingdoms, as well as some outstanding questions arising from these models and recent experimental findings.
Collapse
Affiliation(s)
- Eva E Deinum
- Mathematical and Statistical Methods (Biometris), Plant Science Group, Wageningen University, 6708 PB Wageningen, The Netherlands
| | - Bas Jacobs
- Mathematical and Statistical Methods (Biometris), Plant Science Group, Wageningen University, 6708 PB Wageningen, The Netherlands
| |
Collapse
|
4
|
Li R, Zhao R, Yang M, Zhang X, Lin J. Membrane microdomains: Structural and signaling platforms for establishing membrane polarity. PLANT PHYSIOLOGY 2023; 193:2260-2277. [PMID: 37549378 DOI: 10.1093/plphys/kiad444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 05/16/2023] [Accepted: 07/11/2023] [Indexed: 08/09/2023]
Abstract
Cell polarity results from the asymmetric distribution of cellular structures, molecules, and functions. Polarity is a fundamental cellular trait that can determine the orientation of cell division, the formation of particular cell shapes, and ultimately the development of a multicellular body. To maintain the distinct asymmetric distribution of proteins and lipids in cellular membranes, plant cells have developed complex trafficking and regulatory mechanisms. Major advances have been made in our understanding of how membrane microdomains influence the asymmetric distribution of proteins and lipids. In this review, we first give an overview of cell polarity. Next, we discuss current knowledge concerning membrane microdomains and their roles as structural and signaling platforms to establish and maintain membrane polarity, with a special focus on the asymmetric distribution of proteins and lipids, and advanced microscopy techniques to observe and characterize membrane microdomains. Finally, we review recent advances regarding membrane trafficking in cell polarity establishment and how the balance between exocytosis and endocytosis affects membrane polarity.
Collapse
Affiliation(s)
- Ruili Li
- State Key Laboratory of Tree Genetics and Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- National Engineering Research Center of Tree Breeding and Ecological Restoration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- The Tree and Ornamental Plant Breeding and Biotechnology Laboratory of National Forestry and Grassland Administration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- Institute of Tree Development and Genome Editing, Beijing Forestry University, Beijing, China
| | - Ran Zhao
- State Key Laboratory of Tree Genetics and Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- National Engineering Research Center of Tree Breeding and Ecological Restoration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- The Tree and Ornamental Plant Breeding and Biotechnology Laboratory of National Forestry and Grassland Administration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- Institute of Tree Development and Genome Editing, Beijing Forestry University, Beijing, China
| | - Mei Yang
- State Key Laboratory of Tree Genetics and Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- National Engineering Research Center of Tree Breeding and Ecological Restoration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- The Tree and Ornamental Plant Breeding and Biotechnology Laboratory of National Forestry and Grassland Administration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- Institute of Tree Development and Genome Editing, Beijing Forestry University, Beijing, China
| | - Xi Zhang
- State Key Laboratory of Tree Genetics and Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- National Engineering Research Center of Tree Breeding and Ecological Restoration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- The Tree and Ornamental Plant Breeding and Biotechnology Laboratory of National Forestry and Grassland Administration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- Institute of Tree Development and Genome Editing, Beijing Forestry University, Beijing, China
| | - Jinxing Lin
- State Key Laboratory of Tree Genetics and Breeding, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- National Engineering Research Center of Tree Breeding and Ecological Restoration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- The Tree and Ornamental Plant Breeding and Biotechnology Laboratory of National Forestry and Grassland Administration, College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
- Institute of Tree Development and Genome Editing, Beijing Forestry University, Beijing, China
| |
Collapse
|
5
|
Ruan J, Lai L, Ou H, Yi P. Two subtypes of GTPase-activating proteins coordinate tip growth and cell size regulation in Physcomitrium patens. Nat Commun 2023; 14:7084. [PMID: 37925570 PMCID: PMC10625565 DOI: 10.1038/s41467-023-42879-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2023] [Accepted: 10/24/2023] [Indexed: 11/06/2023] Open
Abstract
The establishment of cell polarity is a prerequisite for many developmental processes. However, how it is achieved during tip growth in plants remains elusive. Here, we show that the RHO OF PLANTs (ROPs), ROP GUANINE NUCLEOTIDE EXCHANGE FACTORs (RopGEFs), and ROP GTPASE-ACTIVATING PROTEINs (RopGAPs) assemble into membrane domains in tip-growing cells of the moss Physcomitrium patens. The confinement of membrane domains requires redundant global inactivation of ROPs by PpRopGAPs and the PLECKSTRIN HOMOLOGY (PH) domain-containing RenGAP PpREN. Unexpectedly, PpRopGAPs and PpREN exert opposing effects on domain size and cell width upon overexpression. Biochemical and functional analyses indicate that PpRopGAPs are recruited to the membrane by active ROPs to restrict domain size through clustering, whereas PpREN rapidly inactivates ROPs and inhibits PpRopGAP-induced clustering. We propose that the activity- and clustering-based domain organization by RopGAPs and RenGAPs is a general mechanism for coordinating polarized cell growth and cell size regulation in plants.
Collapse
Affiliation(s)
- Jingtong Ruan
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, No. 24 South Section 1, Yihuan Road, Wuhou District, Chengdu, Sichuan, 610064, PR China
| | - Linyu Lai
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, No. 24 South Section 1, Yihuan Road, Wuhou District, Chengdu, Sichuan, 610064, PR China
| | - Hongxin Ou
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, No. 24 South Section 1, Yihuan Road, Wuhou District, Chengdu, Sichuan, 610064, PR China
- School of Life Sciences, Tsinghua University, Beijing, 100084, PR China
| | - Peishan Yi
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, No. 24 South Section 1, Yihuan Road, Wuhou District, Chengdu, Sichuan, 610064, PR China.
| |
Collapse
|
6
|
Liu L, Niu L, Ji K, Wang Y, Zhang C, Pan M, Wang W, Schiefelbein J, Yu F, An L. AXR1 modulates trichome morphogenesis through mediating ROP2 stability in Arabidopsis. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 116:756-772. [PMID: 37516999 DOI: 10.1111/tpj.16403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 07/09/2023] [Accepted: 07/17/2023] [Indexed: 08/01/2023]
Abstract
Cell differentiation and morphogenesis are crucial for the establishment of diverse cell types and organs in multicellular organisms. Trichome cells offer an excellent paradigm for dissecting the regulatory mechanisms of plant cell differentiation and morphogenesis due to their unique growth characteristics. Here, we report the isolation of an Arabidopsis mutant, aberrantly branched trichome 3-1 (abt3-1), with a reduced trichome branching phenotype. Positional cloning and molecular complementation experiments confirmed that abt3-1 is a new mutant allele of Auxin resistant 1 (AXR1), which encodes the N-terminal half of ubiquitin-activating enzyme E1 and functions in auxin signaling pathway. Meanwhile, we found that transgenic plants expressing constitutively active version of ROP2 (CA-ROP2) caused a reduction of trichome branches, resembling that of abt3-1. ROP2 is a member of Rho GTPase of plants (ROP) family, serving as versatile signaling switches involved in a range of cellular and developmental processes. Our genetic and biochemical analyses showed AXR1 genetically interacted with ROP2 and mediated ROP2 protein stability. The loss of AXR1 aggravated the trichome defects of CA-ROP2 and induced the accumulation of steady-state ROP2. Consistently, elevated AXR1 expression levels suppressed ROP2 expression and partially rescued trichome branching defects in CA-ROP2 plants. Together, our results presented a new mutant allele of AXR1, uncovered the effects of AXR1 and ROP2 during trichome development, and revealed a pathway of ROP2-mediated regulation of plant cell morphogenesis in Arabidopsis.
Collapse
Affiliation(s)
- Lu Liu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Linyu Niu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Ke Ji
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Yali Wang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Chi Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Mi Pan
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Wenjia Wang
- CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, 200032, China
| | - John Schiefelbein
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan, 48109, USA
| | - Fei Yu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| | - Lijun An
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China
| |
Collapse
|
7
|
Ogawa ST, Kessler SA. Update on signaling pathways regulating polarized intercellular communication in Arabidopsis reproduction. PLANT PHYSIOLOGY 2023; 193:1732-1744. [PMID: 37453128 DOI: 10.1093/plphys/kiad414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 06/22/2023] [Accepted: 06/22/2023] [Indexed: 07/18/2023]
Affiliation(s)
- Sienna T Ogawa
- Department of Botany and Plant Pathology and Center for Plant Biology, Purdue University, West Lafayette, IN 47905, USA
| | - Sharon A Kessler
- Department of Botany and Plant Pathology and Center for Plant Biology, Purdue University, West Lafayette, IN 47905, USA
| |
Collapse
|
8
|
Müller S. Update: on selected ROP cell polarity mechanisms in plant cell morphogenesis. PLANT PHYSIOLOGY 2023; 193:26-41. [PMID: 37070572 DOI: 10.1093/plphys/kiad229] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 03/20/2023] [Accepted: 04/02/2023] [Indexed: 06/19/2023]
Abstract
The unequal (asymmetric) distribution of cell structures and proteins within a cell is designated as cell polarity. Cell polarity is a crucial prerequisite for morphogenetic processes such as oriented cell division and directed cell expansion. Rho-related GTPase from plants (ROPs) are required for cellular morphogenesis through the reorganization of the cytoskeleton and vesicle transport in various tissues. Here, I review recent advances in ROP-dependent tip growth, vesicle transport, and tip architecture. I report on the regulatory mechanisms of ROP upstream regulators found in different cell types. It appears that these regulators assemble in nanodomains with specific lipid compositions and recruit ROPs for activation in a stimulus-dependent manner. Current models link mechanosensing/mechanotransduction to ROP polarity signaling involved in feedback mechanisms via the cytoskeleton. Finally, I discuss ROP signaling components that are upregulated by tissue-specific transcription factors and exhibit specific localization patterns during cell division, clearly suggesting ROP signaling in division plane alignment.
Collapse
Affiliation(s)
- Sabine Müller
- Department of Biology, Friedrich-Alexander University of Erlangen-Nuremberg, 91058 Erlangen, Germany
| |
Collapse
|
9
|
Dong J, Van Norman J, Žárský V, Zhang Y. Plant cell polarity: The many facets of sidedness. PLANT PHYSIOLOGY 2023; 193:1-5. [PMID: 37565502 PMCID: PMC10469367 DOI: 10.1093/plphys/kiad436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Accepted: 07/28/2023] [Indexed: 08/12/2023]
Affiliation(s)
- Juan Dong
- Waksman Institute of Microbiology, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
- Department of Plant Biology, Rutgers, The State University of New Jersey, New Brunswick, NJ 08891, USA
| | - Jaimie Van Norman
- Department of Botany and Plant Sciences, University of California, Riverside, Riverside, CA 92521, USA
- Center for Plant Cell Biology, Institute of Integrative Genome Biology, University of California, Riverside, Riverside, CA 92521, USA
| | - Viktor Žárský
- Department of Experimental Plant Biology, Faculty of Science, Charles University, 128 44, Prague 2, Czech Republic
- Institute of Experimental Botany, Academy of Sciences of the Czech Republic, 165 02 Prague 6, Czech Republic
| | - Yan Zhang
- Department of Plant Biology and Ecology, College of Life Sciences, Nankai University, Tian’jin 300071, China
| |
Collapse
|
10
|
Goldy C, Caillaud MC. Connecting the plant cytoskeleton to the cell surface via the phosphoinositides. CURRENT OPINION IN PLANT BIOLOGY 2023; 73:102365. [PMID: 37084498 DOI: 10.1016/j.pbi.2023.102365] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 03/14/2023] [Accepted: 03/17/2023] [Indexed: 05/03/2023]
Abstract
Plants have developed fine-tuned cellular mechanisms to respond to a variety of intracellular and extracellular signals. These responses often necessitate the rearrangement of the plant cytoskeleton to modulate cell shape and/or to guide vesicle trafficking. At the cell periphery, both actin filaments and microtubules associate with the plasma membrane that acts as an integrator of the intrinsic and extrinsic environments. At this membrane, acidic phospholipids such as phosphatidic acid, and phosphoinositides contribute to the selection of peripheral proteins and thereby regulate the organization and dynamic of the actin and microtubules. After recognition of the importance of phosphatidic acid on cytoskeleton dynamics and rearrangement, it became apparent that the other lipids might play a specific role in shaping the cytoskeleton. This review focuses on the emerging role of the phosphatidylinositol 4,5-bisphosphate for the regulation of the peripherical cytoskeleton during cellular processes such as cytokinesis, polar growth, biotic and abiotic responses.
Collapse
Affiliation(s)
- Camila Goldy
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRAe, F-69342, Lyon, France
| | - Marie-Cécile Caillaud
- Laboratoire Reproduction et Développement des Plantes, Université de Lyon, ENS de Lyon, UCB Lyon 1, CNRS, INRAe, F-69342, Lyon, France.
| |
Collapse
|
11
|
Uyehara AN, Rasmussen CG. Redundant mechanisms in division plane positioning. Eur J Cell Biol 2023; 102:151308. [PMID: 36921356 DOI: 10.1016/j.ejcb.2023.151308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Revised: 03/05/2023] [Accepted: 03/11/2023] [Indexed: 03/18/2023] Open
Abstract
Redundancies in plant cell division contribute to the maintenance of proper division plane orientation. Here we highlight three types of redundancy: 1) Temporal redundancy, or correction of earlier defects that results in proper final positioning, 2) Genetic redundancy, or functional compensation by homologous genes, and 3) Synthetic redundancy, or redundancy within or between pathways that contribute to proper division plane orientation. Understanding the types of redundant mechanisms involved provides insight into current models of division plane orientation and opens up new avenues for exploration.
Collapse
Affiliation(s)
- Aimee N Uyehara
- Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, USA
| | - Carolyn G Rasmussen
- Department of Botany and Plant Sciences, Center for Plant Cell Biology, University of California, Riverside, USA.
| |
Collapse
|