Table 1.

Proteins implicated in Rickettsia invasion of S2R+ cells by RNAi screening

Functional group	Protein implicated in invasion	Internalization ^a (%)	p-value^b	Normalized internalization^c	Hit shared with other screens^d
---	untreated control cells	54 ± 10	---	1 ± 0.09	---
Rho family GTPase	Rac1	37 ± 17	0.0021	0.84 ± 0.5	4,5,7,10
	Rac2	37 ± 8	0.002	0.77 ± 0.09	3,4,5,10
	Rac1 + Cdc42	34 ± 5	0.0003	0.68 ± 0.11	---
	Rac1 + Rac2	39 ± 18	0.0031	0.84 ± 0.46	---
Actin filament nucleator	ARP2	29 ± 9	<0.0001	0.59 ± 0.15	2,3,9
	ARP3	34 ± 9	0.0002	0.67 ± 0.07	2,3,4,6,9
	ARPC1 (p41)	33 ± 16	0.0013	0.66 ± 0.25
	ARPC2 (p34)	30 ± 9	<0.0001	0.63 ± 0.21	2,3
	ARPC4 (p20)	36 ± 12	0.001	0.61 ± 0.22	1,2,3,4,5,6,7,8,10
	ARPC5 (p16)	25 ± 6	<0.0001	0.5 ± 0.04	2,3,4,5,10
Actin nucleation promoting factor	WAVE (SCAR)	18 ± 6	<0.0001	0.38 ± 0.08	1,4,5,6,7,8,9,10
WAVE complex member, regulator	Abi	17 ± 10	<0.0001	0.34 ± 0.18	1,2,3,4,5,7,8
	Kette HEM-protein	31 ± 9	<0.0001	0.57 ± 0.24	1,7,8
	Sra-1	35 ± 6	0.0027	0.55 ± 0.07	1,4,6,7
WASP binding, regulator	WIP veroprolin	38 ± 16	0.005	0.78 ± 0.34
Myosin motor protein	Myosin IA	28 ± 12	<0.0001	0.62 ± 0.37	10
	Myosin II (zipper)	33 ± 6	0.0002	0.72 ± 0.27	1
Endocytic / phagocytic adapter	Hip1R	35 ± 7	0.0005	0.74 ± 0.17	10
Membrane-cytoskeleton linker	MIM homolog	33 ± 8	0.0001	0.69 ± 0.21	9
	Myoblast city	38 ± 4	0.0089	0.87 ± 0.11	7
Actin filament bundling/organizing	α-actinin	34 ± 14	0.0004	0.71 ± 0.19	7,8,10
	Fimbrin	38 ± 6	0.0078	0.86 ± 0.05	7,10
Actin monomer dynamics	Cofilin (twinstar)	40 ± 12	0.0088	0.8 ± 0.09	1,7,10

Percent of R. parkeri internalized 15 mins after infection in cells treated with dsRNA targeting the indicated protein(s). The data presented are the mean ± SD of at least three independent experiments.

Determined by pairwise comparison with the untreated control using the Student’s t-test. p<0.01 was considered statistically significant.

Data were adjusted with the mean percent internalization of matched untreated control cells (duplicate samples) for each day’s experiment set as 1 (100%).

RNAi targeting this protein was also found to ¹reduce lamella formation (Rogers et al., 2003); ²Listeria monocytogenes and/or ³Mycobacterium fortuitum infection (Agaisse et al., 2005); ⁴Candida albicans, ⁵E. coli or ⁶latex bead phagocytosis (Stroschein-Stevenson et al., 2005); ⁷Chlamydia trachomatis infection (Elwell et al., 2008); ⁸Pseudomonas aeruginosa internalization (Pielage et al., 2008); ⁹Rickettsia parkeri infection, or ¹⁰R. parkeri actin tail formation (Serio et al., 2010).