Dectin-1 is required for miR155 upregulation in murine macrophages in response to Candida albicans

Figures & data

Table 1. Differential expression patterns of 9 selected miRNAs in mouse BMDMs with or without exposure to C. albicans heat-killed yeasts or hyphae.

miRNA\Condition	Yeast 8hrs	Hypha 8hrs	Yeast 16hrs	Hypha 16hrs
miR125b	1.19 ± 0.21	2.44 ± 0.05 ^*	2.62 ± 1.43	2.75 ± 0.52 ^*
miR132	1.51 ± 0,73	5.16 ± 1.25 ^**	1.36 ± 0.10	6.37 ± 0.03 ^**
miR146a	3.33 ± 1.20 ^*	8.10 ± 0.72 ^**	2.08 ± 0.17 ^*	3.79 ± 0.95 ^*
miR155	4.65 ± 1.95	6.37 ± 4.33	0.79 ± 0.12	1.50 ± 0.02
miR455	0.82 ± 0.32	2.86 ± 0.09 ^*	0.86 ± 0.34	1.98 ± 1.04
miR9	2.54 ± 0.10 ^*	5.61 ± 0.80 ^***	1.22 ± 0.13	1.52 ± 0.26
miR199	7.51 ± 5.14	32.50 ± 5.26 ^**	1.19 ± 0.31	2.59 ± 0.72
miR221	3.44 ± 1.85	4.04 ± 0.40 ^**	0.71 ± 0.06	2.72 ± 1.64
miR223	3.62 ± 1.96	5.67 ± 0.16 ^**	2.07 ± 0.2	2.35 ± 0.56

Note. Interaction assay of BALB/c BMDMs and heat-killed yeasts or hyphae of C. albicans, employing a MOI of 2 for 8 or 16 hours. Levels of expression were measured by qRT-PCR. Fold change of expression is represented by the mean of 3 independent pooled experiments ± SEM. Statistical analyses were performed by Two-way ANOVA and Tukey's post-test. Bold numbers represent differentially expressed values (p-value < 0.05), whereas asterisks indicate p-value;

(

*  

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p < 0.05,

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**  

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p < 0.01,

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***  

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p < 0.001,

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****  

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p < 0.0001.

Figure 1. Expression levels of miRNAs in BMDMs exposed to UV-killed C. albicans cells. Expression levels of miR132 (A), miR146a (B), and miR155 (C) in C57Bl/6 BMDMs incubated with C. albicans UV-killed yeasts or hyphae at a MOI of 5. Expression levels were measured by qRT-PCR. Results represent the mean of fold change from 3 independent pooled experiments ± SD. Asterisks indicate p-value; (*) p < 0.05, (**) p < 0.01, (***) p < 0.001, (****) p < 0.0001.

Figure 2. Dectin-1 is responsible for regulating miR155 expression in BMDMs exposed to C. albicans hypha. Expression levels of miR155 in (A) BMDMs obtained from different strains of C57Bl/6 mice, incubated for 8 hours with C. albicans UV-killed hyphae or in (B) Wild-type BMDMs incubated with either β-glucan or C. albicans UV-killed hyphae. (A) BMDMs from Wild-type mice and mice deficient in the PRRs TLR2, TLR4, both TLR2 and TLR4, or Dectin 1 (Wild-type, ΔTLR2, ΔTLR4, ΔTLR2/4 and ΔDectin1) were incubated for 8 hours with UV-killed C. albicans hyphae at a MOI of 5. (B) BMDMs from Wild-type C57Bl/6 mice were incubated for 8 hours with either β-glucan (depleted Zymosan) at 100 µg/mL or UV-killed C. albicans hyphae at a MOI of 5. Expression levels were measured by qRT-PCR. Results represent the mean of fold change from 3 independent pooled experiments ± SD. Asterisks indicate p-value; (*) p < 0.05, (**) p < 0.01, (***) p < 0.001, (****) p < 0.0001.

Figure 3. Dectin-1 activation of miR155 occurs via a Syk-dependent pathway. Effect of Dectin-1 pathway inhibitors on the expression of miR155 by different C57Bl/6 BMDMs with or without exposure to C. albicans UV-killed hyphae at an MOI of 5 for 8 hours. BMDMs with or without exposure to Dectin-1 inhibitors GW5074 (inhibits Raf-1), R406 (Syk inhibitor) or both compounds. Expression levels were measured by qRT-PCR. Results represent the mean of fold change from 3 independent pooled experiments ± SD. Asterisks indicate p-value; (*) p < 0.05, (**) p < 0.01, (***) p < 0.001, (****) p < 0.0001.

Figure 4. Model of miR155 activation in BMDMs exposed to C. albicans hyphae. miR155 activation by C. albicans. Exposure of β-glucans in the fungal cell wall interact with Dectin 1, inducing a Syk-dependent pathway that results in the upregulation of mature miR155. Activation of either TLR 2 or 4 inhibits the accumulation of the mature miRNA.