High impact information on ARP2

• DISTORTED3/SCAR2 is a putative arabidopsis WAVE complex subunit that activates the Arp2/3 complex and is required for epidermal morphogenesis [1].
• All seven subunits of the ARP2/3 complex have been identified in Arabidopsis thaliana, and mutation of at least three of the subunits results in defects in epidermal cell expansion, including distorted trichomes [2].
• ACTIN-RELATED PROTEINS 2 and 3 form the major subunits of the ARP2/3 complex, which is known as an important regulator of actin organization in diverse organisms [3].
• Here, we report that two genes, WURM and DISTORTED1, which are important for cell shape control in Arabidopsis, encode the plant ARP2 and ARP3 orthologs, respectively [3].
• Analysis of double mutants provides genetic evidence that BRK1 functions in a pathway with the ARP2/3 complex [4].

Biological context of ARP2

• Arabidopsis NAP1 is essential for Arp2/3-dependent trichome morphogenesis [5].
• BRICK1/HSPC300 functions with SCAR and the ARP2/3 complex to regulate epidermal cell shape in Arabidopsis [4].
• The molecular genetics of trichome distortion in Arabidopsis is a powerful system to understand how signaling pathways and ARP2/3 control multicellular development [6].
• A. thaliana appears to have only one AtARP2 gene which contains 14 introns, an unusually large number when compared to 4 or 5 introns in the actin genes isolated so far [7].

Anatomical context of ARP2

• The SCAR/WAVE family represents a group of Arp2/3 activators that are associated with lamellipodia formation [5].
• Subsequent analysis of the actin cytoskeleton in trichomes of the distorted mutants, alien, crooked, distorted1, gnarled, klunker and wurm uncovered actin organization defects in each case [8].

Regulatory relationships of ARP2

• The patterns and levels of actin polymerization observed in Atnap-1 and Atpir-1 mutant trichome cells and epidermal pavement cell morphology is consistent with Arabidopsis NAP and PIR proteins forming a WAVE complex that activates ARP2/3 activity [9].

Other interactions of ARP2

• In animal cells ARP2/3 activity is regulated by WAVE complexes that contain WAVE/SCAR proteins, PIR121, Nap125, and other proteins [9].
• The GRL gene encodes the Arabidopsis homolog of NAP125, which in animals is known to act as one regulator of the ARP2/3-regulating complex WAVE-HSPC300 [10].

References