Differential use of the regulatory elements of the XXXX enhancer in cultured @entity19 lung (MLg), lens (alpha TN4-1) and muscle (C2C12) cells.

@entity1 @entity71865 @entity19577 @entity19 @entity1014 @entity9828
The @entity19 @entity71865 -encoding gene (alpha B-cry) is highly expressed in the lens and expressed to lesser extents in other tissues. Here, we investigated alpha B-cry expression in @entity19 -lung-derived MLg cells. Two sizes of MLg alpha B-cry transcripts comigrated with alpha B-cry transcripts contained in total and poly(A)+RNA from @entity19 lung, with preference for the larger species in the MLg cells. Expression of both alpha B-cry promoter/cat reporter gene constructs and alpha B-cry enhancer (nt -427/-259)/herpes simplex virus (HSV) @entity1014 kinase promoter (ptk)/ @entity1 growth hormone reporter gene (hGH) constructs was studied in transfected MLg cells and the results compared with those obtained from alpha TN4-1 lens and C2C12 muscle cells. The alpha B-cry enhancer increased activity of the endogenous and tk promoters approx. 2-fold in the MLg cells, in contrast to its 3-7-fold effect in alpha TN4-1 cells and 17-20-fold effect in C2C12 myotubes. Site-specific mutagenesis of the previously identified enhancer control elements, alpha B-E-1 (nt -407 to -397), alpha BE-2 (-360 to -327) and @entity19577 (-300 to -288), decreased enhancer strength in transfected MLg cells. @entity9828 footprinting showed that MLg nuclear proteins occupy only alpha BE-1 and alpha BE-2. Previous data have shown that lens cells use alpha BE-1, alpha BE-2 and alpha BE-3, while muscle cells use, in addition, the @entity19577 ( @entity19577 ). Thus, the present experiments correlate tissue-specific enhancer strength and the number of control elements utilized.
