Tissue- and stratum-specific expression of the human involucrin promoter in transgenic mice.

Abstract

Involucrin is a marker of keratinocyte terminal differentiation and is expressed only in the suprabasal layers of stratified squamous epithelium. In a previous study with various cell types in culture, we noted that expression of the putative human involucrin promoter was keratinocyte specific. To determine if this promoter is sufficient to direct expression to the suprabasal cells of stratified squamous epithelia in vivo, we have now generated transgenic mouse lines harboring the involucrin promoter sequences linked to a (3ga-lactosidase reporter gene. In the resulting lines, -galactosidase was expressed in the suprabasal compartment of stratified squamous epithelia and in hair follicles in a tissue-specific manner. In the palate, distinct vertical stacks of 3galacto-sidase-expressing cells were present, suggesting movement of clonally derived ceUs through the epithelium. The involucrin gene has a single intron upstream of the translational start site, and removal of this intron did not affect tissue-or stratumspecific expression. These results show that the 3.7-kb involucrin upstream sequences contain all the information necessary for a high level of tissue-and stratum-specific expression.

Durable and stratum-specific gene expression in epidermis

“…In an earlier study, a 2500-bp fragment of the hINV upstream region was shown to confer tissue-and stratum-specific expression (Figure 1). 14 In this fragment, consensus SP1 and AP1 binding sites are located primarily at the 5' and 3' termini of this region while the central region is devoid of transcription binding sites. 17 A 754-bp fragment was derived from this upstream regulatory region including AP1-5, SP1 and AP1-1 binding sites by deletion of the central BglII (Ϫ2100)/MscI (Ϫ192) 1908-bp fragment.…”

“…When the 754-bp fragment was used to drive LacZ expression in transgenic mice, tissue-and stratum-specific expression was evident, similar to that observed for the full-length promoter ( Figure 1). 14 …”

“…Tissue samples were harvested from mice and analyzed by histochemical staining for ␤-galactosidase activity as described previously. 14 …”

“…12 A 2500-base fragment of hINV gene upstream regulatory region is sufficient to drive tissue-and stratum-specific expression in transgenic mice. 13,14 Deletion mapping studies have identified two regulatory regions that contribute to differentiation-induced activity of this promoter; a distal element (Ϫ2473/Ϫ2088) containing AP-1 and Sp1 binding sites, and a proximal region (Ϫ185/Ϫ1) with a critical AP-1 binding site overlapping with a consensus binding site for ets transcription factor. [15][16][17] We have explored the potential of these critical regulatory sequences of the hINV to restrict retrovirus-driven expression of the transgene to the suprabasal layers of the epidermis.…”

Omomyc expression in skin prevents Myc-induced papillomatosis

“…Consequently, Myc activation is sufficient to induce profound hyperplasia and tumorigenesis. 11 Expression of Omomyc was targeted to suprabasal keratinocytes using the human involucrin promoter ( Figure 3A) 11,15 and expression of Omomyc protein in skin in vivo assessed immunohistochemically using a rabbit antiOmomyc antibody raised against the leucine zipper mutated region. This antibody exhibited no significant binding to epidermis of single transgenic inv-c-MycER TAM mice, indicating lack of cross-reaction with Myc-ER TAM .…”