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Suprabasal expression of a dominant-negative RXR alpha mutant in transgenic mouse epidermis impairs regulation of gene transcription and basal keratinocyte proliferation by RAR-selective retinoids.

Abstract：

:To determine whether 9-cis retinoic acid receptors (RXRs) regulate the biological activity of all-trans retinoic acid (tRA) and its receptors (RARs) in skin, we have targeted a dominant-negative RXR alpha (dnRXR alpha) lacking transactivation function AF-2 to differentiated suprabasal keratinocytes in the epidermis of transgenic mice. Driven by the suprabasal-specific keratin-10 gene promoter, expression of dnRXR alpha severely reduced the ability of RAR-selective ligands tRA and CD367 to induce epidermal mRNA levels of the CRABPII, CRBPI, and CRBPII genes, which contain RA-responsive elements (RAREs) DR1 and/or DR2. It also reduced gene-specific, synergistic induction of CRBPI mRNA by a combination of CD367 and RXR-selective SR11237. Like endogenous RXR alpha, dnRXR alpha in epidermal nuclear extracts from the transgenic mice competitively formed heterodimers with endogenous RAR gamma on RAREs, suggesting that dnRXR alpha impairs retinoid signaling by competing with endogenous RAR gamma-RXR alpha heterodimers. Histologically, the epidermis of dnRXR alpha mice showed no detectable developmental abnormalities. Surprisingly, in adult animals, the suprabasal expression of dnRXR alpha significantly reduced the ability of topically applied tRA to stimulate proliferation of undifferentiated keratinocytes in the basal layer of epidermis. RXR-selective ligands alone had no detectable effects on both normal and transgenic mouse epidermis. Accordingly, we suggest that in vivo: (1) in suprabasal keratinocytes, retinoids regulate gene transcription via RAR-RXR heterodimers in which RAR confers a predominant ligand response, whereas RXR AF-2 is required for liganded RAR AF-2 to efficiently trans-activate target genes, and (2) this suprabasal RXR-assisted mechanism indirectly regulates proliferation of basal keratinocytes likely via intercellular signaling.

journal_name

Genes Dev

journal_title

Genes & development

authors

Feng X,Peng ZH,Di W,Li XY,Rochette-Egly C,Chambon P,Voorhees JJ,Xiao JH

doi

10.1101/gad.11.1.59

subject

Has Abstract

pub_date

1997-01-01 00:00:00

pages

59-71

issue

eissn

0890-9369

issn

1549-5477

journal_volume

pub_type

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Suprabasal expression of a dominant-negative RXR alpha mutant in transgenic mouse epidermis impairs regulation of gene transcription and basal keratinocyte proliferation by RAR-selective retinoids.