scholarly journals Barley ROP-Interactive Partner-a organizes into RAC1- and MICROTUBULE-ASSOCIATED ROP-GTPASE ACTIVATING PROTEIN 1-dependent membrane domains

2020 ◽  
Vol 20 (1) ◽  
Author(s):  
Caroline Hoefle ◽  
Christopher McCollum ◽  
Ralph Hückelhoven
2019 ◽  
Author(s):  
Caroline Hoefle ◽  
Christopher McCollum ◽  
Ralph Hückelhoven

AbstractSmall ROP (also called RAC) GTPases are key factors in polar cell development and in interaction with the environment. ROP-Interactive Partner (RIP) proteins are predicted scaffold or ROP-effector proteins, which function downstream of activated GTP-loaded ROP proteins in establishing membrane heterogeneity and cellular organization. Grass ROP proteins function in cell polarity, resistance and susceptibility to fungal pathogens but grass RIP proteins are little understood.We found that the barley (Hordeum vulgare L.) RIPa protein can interact with barley ROPs in yeast. Fluorescent-tagged RIPa, when co-expressed with the constitutively activated ROP protein CA RAC1, accumulates at the cell periphery or plasma membrane. Additionally, RIPa, locates into membrane domains, which are laterally restricted by microtubules, when co-expressed with RAC1 and MICROTUBULE-ASSOCIATED ROP-GTPASE ACTIVATING PROTEIN 1. Both structural integrity of MICROTUBULE-ASSOCIATED ROP-GTPASE ACTIVATING PROTEIN 1 and microtubule stability are key to maintenance of RIPa-labeled membrane domains. In this context, RIPa also accumulates at the interface of barley and invading hyphae of the powdery mildew fungus Blumeria graminis f.sp. hordei.Data suggest that barley RIPa interacts with barley ROPs and specifies RAC1 activity-associated membrane domains with potential signaling capacity. Lateral diffusion of this RAC1 signaling capacity is restricted the resulting membrane heterogeneity requires intact microtubules and MICROTUBULE-ASSOCIATED ROP-GTPASE ACTIVATING PROTEIN 1. Focal accumulation of RIPa at sites of fungal attack may indicate locally restricted ROP activity at sites of fungal invasion.


2011 ◽  
Vol 23 (6) ◽  
pp. 2422-2439 ◽  
Author(s):  
Caroline Hoefle ◽  
Christina Huesmann ◽  
Holger Schultheiss ◽  
Frederik Börnke ◽  
Götz Hensel ◽  
...  

Author(s):  
E.L. Benedetti ◽  
I. Dunia ◽  
Do Ngoc Lien ◽  
O. Vallon ◽  
D. Louvard ◽  
...  

In the eye lens emerging molecular and structural patterns apparently cohabit with the remnants of the past. The lens in a rather puzzling fashion sums up its own natural history and even transient steps of the differentiation are memorized. A prototype of this situation is well outlined by the study of the lenticular intercellular junctions. These membrane domains exhibit structural, biochemical and perhaps functional polymorphism reflecting throughout life the multiple steps of the differentiation of the epithelium into fibers and of the ageing process of the lenticular cells.The most striking biochemical difference between the membrane derived from the epithelium and from the fibers respectively, concerns the presence of the 26,000 molecular weight polypeptide (MP26) in the latter membranes.


Author(s):  
J.M. Robinson ◽  
J.M Oliver

Specialized regions of plasma membranes displaying lateral heterogeneity are the focus of this Symposium. Specialized membrane domains are known for certain cell types such as differentiated epithelial cells where lateral heterogeneity in lipids and proteins exists between the apical and basolateral portions of the plasma membrane. Lateral heterogeneity and the presence of microdomains in membranes that are uniform in appearance have been more difficult to establish. Nonetheless a number of studies have provided evidence for membrane microdomains and indicated a functional importance for these structures.This symposium will focus on the use of various imaging modalities and related approaches to define membrane microdomains in a number of cell types. The importance of existing as well as emerging imaging technologies for use in the elucidation of membrane microdomains will be highlighted. The organization of membrane microdomains in terms of dimensions and spatial distribution is of considerable interest and will be addressed in this Symposium.


Author(s):  
Michael Edidin

Cell surface membranes are based on a fluid lipid bilayer and models of the membranes' organization have emphasised the possibilities for lateral motion of membrane lipids and proteins within the bilayer. Two recent trends in cell and membrane biology make us consider ways in which membrane organization works against its inherent fluidity, localizing both lipids and proteins into discrete domains. There is evidence for such domains, even in cells without obvious morphological polarity and organization [Table 1]. Cells that are morphologically polarised, for example epithelial cells, raise the issue of membrane domains in an accute form.The technique of fluorescence photobleaching and recovery, FPR, was developed to measure lateral diffusion of membrane components. It has also proven to be a powerful tool for the analysis of constraints to lateral mobility. FPR resolves several sorts of membrane domains, all on the micrometer scale, in several different cell types.


2015 ◽  
Vol 57 ◽  
pp. 177-187 ◽  
Author(s):  
Jennifer N. Byrum ◽  
William Rodgers

Since the inception of the fluid mosaic model, cell membranes have come to be recognized as heterogeneous structures composed of discrete protein and lipid domains of various dimensions and biological functions. The structural and biological properties of membrane domains are represented by CDM (cholesterol-dependent membrane) domains, frequently referred to as membrane ‘rafts’. Biological functions attributed to CDMs include signal transduction. In T-cells, CDMs function in the regulation of the Src family kinase Lck (p56lck) by sequestering Lck from its activator CD45. Despite evidence of discrete CDM domains with specific functions, the mechanism by which they form and are maintained within a fluid and dynamic lipid bilayer is not completely understood. In the present chapter, we discuss recent advances showing that the actomyosin cytoskeleton has an integral role in the formation of CDM domains. Using Lck as a model, we also discuss recent findings regarding cytoskeleton-dependent CDM domain functions in protein regulation.


2020 ◽  
Author(s):  
Lungwani Muungo

ADP ribosylation factor GTPase-activating protein 3 (ARFGAP3) is a GTPase-activating protein that associates with the Golgiapparatus and regulates the vesicular trafficking pathway. In the present study, we examined the contribution of ARFGAP3 toprostate cancer cell biology. We showed that ARFGAP3 expression was induced by 100 nM of dihydrotestosterone (DHT) atboth the mRNA and protein levels in androgen-sensitive LNCaP cells. We generated stable transfectants of LNCaP cells withFLAG-tagged ARFGAP3 or a control empty vector and showed that ARFGAP3 overexpression promoted cell proliferation andmigration compared with control cells. We found that ARFGAP3 interacted with paxillin, a focal adhesion adaptor protein thatis important for cell mobility and migration. Small interfering RNA (siRNA)-mediated knockdown of ARFGAP3 showed thatARFGAP3 siRNA markedly reduced LNCaP cell growth. Androgen receptor (AR)-dependent transactivation activity on prostatespecificantigen (PSA) enhancer was synergistically promoted by exogenous ARFGAP3 and paxillin expression, as shown byluciferase assay in LNCaP cells. Thus, our results suggest that ARFGAP3 is a novel androgen-regulated gene that can promoteprostate cancer cell proliferation and migration in collaboration with paxillin.


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