MacLeod, M. | Search bioRxiv

bioRxiv2024

A molecular basis for plant SCAR/WAVE functional divergence

Dynamic actin cytoskeleton reorganisation enables plant developmental processes requiring polarised transport such as root hair and leaf trichome formation. The SCAR/WAVE complex plays a crucial role in regulating these dynamics through ARP2/3-mediated actin branching. SCAR/WAVE genes occur as small families across a wide range of plant species but whether and how they fulfil different functions remains unclear. We utilise a systematic chimaera approach to define the differential functionality of two closely related Medicago truncatula SCAR proteins in plant development. We show that SCAR/WAVE contribution to Medicago truncatula root hair or Arabidopsis thaliana trichome formation is dependent on two central intrinsically disordered regions (IDRs). Differential functionalities of Medicago truncatula SCAR proteins were furthermore associated with the presence/absence of a 42-amino acid sequence within the IDR that impacted protein stability. Through uncovering a molecular basis for functional differences, we advance our understanding of plant SCAR/WAVE complexes. One Sentence SummaryIntrinsically disordered regions in SCAR/WAVE proteins drive diverse functions in root hair and leaf trichome development.

plant biology↗

bioRxiv2019

A novel methodology for defining stromal expression of atypical chemokine receptors in vivo

Analysis of chemokine receptor, and atypical chemokine receptor, expression is frequently hampered by the lack of availability of high-quality antibodies and the species-specificity of those that are available. We have previously described methodology utilising Alexa-Fluor labelled chemokine ligands as versatile reagents to detect receptor expression. Previously this has been limited to haematopoietic cells and methodology for assessing expression of receptors on stromal cells has been lacking. Amongst chemokine receptors the ones most frequently expressed on stromal cells belong to the atypical chemokine receptor subfamily. These receptors do not signal in the classic sense in response to ligand but scavenge their ligands and degrade them and thus sculpt in vivo chemokine gradients. Here we demonstrate the ability to use either intratracheal, or intravenous, Alexa-Fluor labelled chemokine administration to detect stromal cell populations expressing the atypical chemokine receptor ACKR2. Using this methodology we demonstrate, for the first time, expression of ACKR2 on blood endothelial cells. This observation sets the lung aside from other tissues in which ACKR2 is exclusively expressed on lymphatic endothelial cells. In summary therefore we described a novel method for the in situ labelling of atypical chemokine receptor expressing cells appropriate for subsequent flow cytometric analysis. We propose that this methodology will work in a range of species and for a range of receptors and therefore will have significant versatility

immunology↗