1. Mask Proteins Are Cofactors of Yorkie/YAP in the Hippo Pathway
Clara M. Sidor, Ruth Brain, Barry J. Thompson 
Current Biology 
Volume 23, Issue 3, Pages (February 2013)
DOI: /j.cub
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2. Current Biology 2013 23, 223-228DOI: (10.1016/j.cub.2012.11.061)
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3. Figure 1
The mask Gene Is Required for Tissue Growth in the Drosophila Wing and Eye
(A) Control adult Drosphila wing (MS1096.G4).
(B) RNAi knockdown of mask results in an abnormally small wing.
(C) RNAi knockdown of wts results in an abnormally large wing.
(D) Control adult Drosophila eye (ey.G4 GMR.G4).
(E) RNAi knockdown of mask results in an abnormally small eye.
(F) RNAi knockdown of wts results in an abnormally large eye.
(G) Section through an adult eye showing multiple ommatidia.
(H) RNAi knockdown of mask causes occasional loss of pigment cells and moderate disorganization of the ommatidia but does not cause loss of photoreceptor cells.
(I) RNAi knockdown of the wts gene causes a strong increase in pigment cells.
(J) Control (white) adult eye. Top view is shown in (J′).
(K) A mask10.22 homozygous mutant eye is small and rough. Top view is shown in (K′).
(L) Third-instar wing imaginal disc containing control (GFP-negative) mitotic recombination clones and sister twin-spot clones (2× GFP) of similar size.
(M) Third-instar wing imaginal disc containing mask10.22 homozygous mutant clones (GFP-negative) that are drastically smaller than their sister twin spots (2× GFP).
(N) Quantification of the ratio between clone and twin sizes in (L) and (M).
Current Biology  , DOI: ( /j.cub )
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4. Figure 2
mask Is Required for Yki Target-Gene Expression and Forms a Complex with Yki and Sd on Target-Gene Promoter DNA
(A) Control third-instar wing imaginal disc stained with an anti-Mask antibody (green).
(B) Expression pattern of the four-jointed.lacZ reporter gene in a control wing disc.
(C) Expression pattern of the DIAP.lacZ reporter gene in a control wing disc.
(D) RNAi knockdown of mask in the posterior compartment (dotted line) reduces the level of Mask protein expression.
(E) RNAi knockdown of mask in the posterior compartment (dotted line) reduces the level of four-jointed.lacZ expression.
(F) RNAi knockdown of mask in the posterior compartment (dotted line) reduces the level of DIAP.lacZ expression.
(G) A mask10.22 homozygous mutant clone (nlsGFP-positive) shows reduced expression of DIAP.lacZ (G′) compared to control neighboring cells.
(H) A mask10.22 homozygous mutant clone (nlsGFP-positive) shows reduced expression of expanded.lacZ (H′) compared to control neighboring cells.
(I) A mask10.22 homozygous mutant clone (nlsGFP-positive) in the center of the wing pouch shows reduced expression of four-jointed.lacZ (I′).
(J) Schematic diagram of the Mask protein domain structure.
(K) CoIP of GFP-tagged Yki with FLAG-tagged Mask ankyrin-repeat domains.
(L) DNA pull-down with either actin or DIAP1 DNA sequences from extracts of S2 cells transfected with Yki-HA and Sd-FLAG. Mask, Yki, and Sd bind to DIAP1, but not to actin.
(M) DNA pull-down with either actin or DIAP1 DNA sequences from extracts of S2 cells. Sd RNAi reduces the specific binding of Mask to the DIAP1 promoter.
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5. Figure 3
Mask Is Required for Yki-Driven Cell Proliferation and Target-Gene Transcription
(A) Control clones (GFP-positive) in a third-instar wing imaginal disc.
(B) Overexpression of Yki-V5 drives overproliferation of cells, leading to large clones.
(C) Mutation of mask inhibits cell proliferation, resulting in small clones.
(D) Overexpression of Yki-V5 in mask mutant cells fails to drive overproliferation.
(E) Quantification of clone sizes in (A)–(D).
(F) Yki-V5 localizes to both cytoplasm and nucleus.
(G) Yki-V5 localizes to both cytoplasm and nucleus in mask mutant cells.
(H) Control mosaic analysis with a repressible cell marker (MARCM) clones (GFP-positive) in a third-instar wing imaginal disc.
(I) wtsX1 mutant clones overproliferate, leading to enlarged clone sizes.
(J) mask10.22 mutant clones proliferate slowly, leading to small clone sizes.
(K) mask10.22 wtsX1 double mutants are smaller than wtsX1 mutants.
(L) Quantification of clone sizes in (H)–(K).
(M–P) Scanning electron micrographs of control (M), mask mutant (N), wts mutant (O), and mask, wts double mutants (P).
(Q) wtsX1 mutant clones show upregulation of expanded.lacZ expression.
(R) mask10.22 wtsX1 double mutants fail to upregulate expanded.lacZ expression.
(S) mask10.22 wtsX1 double mutants fail to maintain four-jointed.lacZ expression.
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6. Figure 4 Human Homologs of Mask
(A) Coimmunoprecipitation of GFP-tagged YAP with FLAG-tagged Mask1 or Mask2 in the presence of crosslinker in HEK293 cells.
(B) FLAG-tagged YAPS5A drives transcriptional activation of CTGF in quantitative RT-PCR assays from MCF10A cells. Knockdown of both Mask1 and Mask2 reduces YAPS5A-dependent transcription of CTGF, similarly to knockdown of YAP itself.
(C) Human Mask1 and YAP colocalize in the nucleus of sparse HEK293 cells.
(D) Human Mask2 and YAP colocalize in the cytoplasm of dense HEK293 cells.
(E) Human Mask1, Mask2, and YAP show similar redistribution from the nucleus to the cytoplasm upon contact inhibition in Caco2 cells.
(F) YAP is mainly nuclear in the basal stem cell layer of human esophageal epithelia.
(G) Mask1 is both cytoplasmic and nuclear in the basal stem cell layer of human esophageal epithelia.
(H) Mask2 is mainly nuclear in the basal stem cell layer of human esophageal epithelia, but it is also weakly expressed and nuclear in other cells of the epithelium.
(I) Model showing Mask as a novel cofactor for Yki/YAP. The localization of the two proteins is coregulated. Mask and Yki/YAP form a complex with transcription factors such as Sd/TEAD to induce transcription of target genes.
Current Biology  , DOI: ( /j.cub )
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