Figure 3. OTX2 can activate the human
TYR promoter even in the absence of DNA binding sites.
OTX2 directly activates the TYR promoter through
specific OTX2 binding sites 1 (−361 to −356), 2
(−354 to −349) and 3 (−226 to −221) and indirectly via
MITF sites. A: Luc-reporter constructs containing
disrupted MITF binding sites at positions −104 to −99
(mM=mutation of the M box) and −12 to −7 (mE=mutation of
the E box). B: Disruptions of OTX2 binding sites
1, 2, and/or 3 (renamed m1, m2, and m3) in
the human TYR promoters −152 or −462 were cotransfected
into ARPE-19 cells with MITF-A or OTX2 factors, their
combination, or with an empty expression vector (pCR3).
Normalized luciferase activities are relative to TYR
promoter construct −152 (=1) cotransfected with the empty
expression vector pCR3 (=vector only). Data are means±SEM from
two independent transfections each performed in triplicate.