Supplementary Figure 1. CLICR allows clustering and activation of cytoplasmic protein targets. (a, b) Upon light activation, the Cry2 (red) and LRP6c (green) components co-cluster due to the heterodimeric interaction between the LZa and LZb adapters in conjunction with Cry2 clustering. Panels (a) and (b) demonstratee the same concept as in Figure 1B and C, but here we show that different fusion architectures (N-terminal LZa, C-terminal LZb) can achievee the same results. (c) A luciferase reporter of -catenin ( -cat) activity, which is induced when destruction complex (DC)-mediated inhibition of -catenin is released, allows readout of the -catenin pathway activation. (d) CLICR clustering of cytoplasmic LRP6c activates -catenin signaling (means + 1 s.d., *p = 0.0495, Mann-Whitney Wilcoxon test, n = 3 replicates). (e, f) CLICR clustering of cytoplasmic Rac1 induces membrane translocation of both CLICR components, consistent with previous reports of Rac1 clustering (16) and demonstrating CLICR modularity in regulating a different cytoplasmic protein through indirect clustering. Scale bars, 20 m.
Supplementary Figure 2. Cry2 membrane translocation through CLICR clustering. (a, b) An N-terminal LZa fusion on the Cry2 module exhibits translocationn from the cytoplasm to membrane-tethered GFP-LZb upon CLICR induced avidity increase. Figures 1 d, e demonstrate a similar result for Cry2-mCh with a C-terminal LZa. Scale bar, 20 m.
Supplementary Figure 3. CLICR enables activation of full-length transmembrane LRP6 co-receptor. (a) The CLICR method was applied to cluster and activate exogenously expressed LRP6-GFP- LZb. (b) Expression of LRP6-GFP alone exhibits receptor localization to both plasma membrane and non-plasma membrane compartments. Both C-terminal (c) and N-terminal (d) LZa fusions of Cry2 exhibit light-dependent membrane translocation and colocalization with LRP6-GFP- LZb. By comparison, Cry2 constructs lacking LZa exhibit clustering but no membrane localization or co-localization with LRP6-GFP-LZb (e, f). (g) -catenin pathway activation was induced via CLICR using either N- or C-terminal LZa fusion to Cry2, albeit with high background in the dark and with lower signal induction compared to cytoplasmic Cry2-mCh- LRP6c activation. (h) High basal -catenin signaling in (g) can be attributed to receptor overexpression, as unilluminated reporter cells expressing only the full length LRP6 receptor fused to either GFP or GFP-LZb both show markedly higher pathway activation than the cytoplasmic Cry2-mCh-LRP6c construct. Graphs show means + 1 s.d., *p = 0.0495, Mann- Whitney Wilcoxon test, n = 3 replicates. Scale bars = 20 m.
Supplementary Figure 4. Expression of full-length LRP6 fused to Cry2-mCh is not suitable for optical induction of -catenin activity. 3500 Relative Light Units 3000 2500 2000 1500 1000 500 0 Full length transmembrane receptor LRP6 was fused at the C-terminus to Cry2-mCherry to investigate whether an LRP6-Cry2 direct fusion could be used to optically regulatee receptor clustering and activation (a), as had previously been demonstrated for cytoplasmic proteins (16). (b) Cytoplasmic clustering of a Cry2-mCh fused to the endodomain of LRP6 (Cry2-mCh- LRP6c) allows photoactivation of a luciferase reporter for -catenin in 293T cells. In contrast, LRP6(FL)-Cry2-mCh exhibits high basal signaling in the dark, and blue light exposure induces an unexpected decrease in -catenin signal. Graphs shows mean + 1 s.d., n = 3 replicates.
Supplementary Figure 5. SH2-N translocation to focal adhesions is dependent on PDGFR, but not FGFR1, activity. Whole cell light activation stimulates SH2-N translocation to focal adhesion structures (top row). This translocation is largely abrogated in the presence of PDGFR inhibitor (middle row), but not in the presence of FGFR1 inhibitor (bottom row), suggesting that PDGFR activity must remain intact to observe this phenotype and that CLICR clustering is modulating PDGFR activity. All illuminated images were taken after 6.5 minutes of illumination. Scale bar = 20 m.
Supplementary Figure 6. Cells overexpressing RTKs exhibit a higher sensitivity to extracellular ligand. RTK overexpression may alter native cellular properties, for example sensitivity to extracellular ligand. A CLICR approach should in principle display significantly less such artifact. To observe this, naïve 3T3s or 3T3s expressing PDGFR -mch-cry2 or SH2-N were starved and treated with increasing concentrations of the PDGF-BB ligand. (a) Western blot analysis (a) and quantification reveals that cells overexpressing RTKs indeed exhibited enhanced canonical RTK signal activation, while cells expressing SH2-N showed little or no elevated signal over naïve cells. The mild activation of perk staining observed in SH2-N expressing cells at higher PDGF- BB induction may be due to the affinity of the SH2N binding adapter for phospho-tyrosine, which is elevated upon PDGF-BB stimulation.
Supplementary Figure 7. Wortmannin prevents SH2-N dependent polarity establishment. (a) Whole field illumination of SH2-N expressing fibroblasts in the presencee of PI3K inhibitor wortmannin reveals that light-dependent polarity establishment is PI3K dependent. Cells exhibit transient lamellipodial protrusions in all directions that collapse within minutes (arrows). (b) Focal illumination of these cells again reveals an inability to extend sustained lamellipodia and establish a PIP3 gradient. Time given in minutes:seconds, scale bars = 20 m.
Supplementary Figure 8. F3-N expression does not alter basal phosphorylation in 3T3s To ascertain whether expression of F3-N alters endogenous signaling, wild-type 3T3s and 3T3s expressing F3-N were maintained in the dark and probed through Western blot analysis using broadly specific phospho-tyrosine, -serine, and -threonine antibodies. The lack of observable difference suggests that the unactivated F3-N fusion imparts little to no change on basal signaling levels.
Supplementary Figure 9. Uncropped Western blot images from main text figures. Images depict uncropped western blot from data in the main text. Dotted lines represent the relevant bands that were cropped for the main text figures. Red indicates saturated pixels.
Supplementary Table 1. Initial constructs tested for cytoplasmic CLICR observation and activation. Construct Expression Visible Light-Induced Clusters? Cry2-mCh-LZa +++ YES LZa-mCh-Cry2 +++ YES LZa-Cry2-mCh +++ NO Construct Expression Co-clusters? LZb-LRP6c-GFP + YES LZb-GFP-LRP6c ++ YES GFP-LRP6c-LZ ++ NO Above are listed the initial constructs tested for cytoplasmic CLICR, how well they expressed in HEK 293T cells, and whether or not they clustered (for Cry2-LZa fusions) or co-clustered, via CLICR, with Cry2 (for GFP-LZb fusions).