Indicator expression directed by regulatory sequences of the glial fibrillary acidic protein (GFAP) gene: In vivo comparison of distinct GFAP‐lacZ transgenes

Abstract

An increase in the expression of the glial fibrillary acidic protein (GFAP) gene by astrocytes appears to constitute a crucial component of the brain's response to injury because it is seen in many different species and features prominently in diverse neurological diseases. Previously, we have used a modified GFAP gene (C-339) to target the expression of beta-galactosidase (beta-gal) to astrocytes in transgenic mice (Mucke et al.; New Biol 3:465-474 1991). To determine to what extent the in vivo expression of GFAP-driven fusion genes is influenced by intragenic GFAP sequences, the E. coli lacZ reporter gene was either placed downstream of approximately 2 kb of murine GFAP 5' flanking region (C-259) or ligated into exon 1 of the entire murine GFAP gene (C-445). Transgenic mice expressing C-259 versus C-445 showed similar levels and distributions of beta-gal activity in their brains. Exclusion of intragenic GFAP sequences from the GFAP-lacZ fusion gene did not diminish injury-induced upmodulation of astroglial beta-gal expression or increase beta-gal expression in non-astrocytic brain cells. These results demonstrate that 2 kb of murine GFAP 5' flanking region is sufficient to restrict transgene expression primarily to astrocytes and to mediate injury-responsiveness in vivo. This sequence therefore constitutes a critical target for mediators of reactive astrocytosis. While acute penetrating brain injuries induced focal increases in beta-gal expression around the lesion sites in C-259, C-445, and C-339 transgenic mice, infection of C-339 transgenic mice with scrapie led to a widespread upmodulation of astroglial beta-gal expression. Hence, GFAP-lacZ transgenic mice can be used to monitor differential patterns of astroglial activation in vivo. These and related models should facilitate the assessment of strategies aimed at the in vivo manipulation of GFAP expression and astroglial activation.

Astrocyte-specific expression of tyrosine hydroxylase after intracerebral gene transfer induces behavioral recovery in experimental Parkinsonism

“…[32][33][34][35] Use of the GFAP promoter permits these cells to be specifically targeted in vivo. Another attribute of the GFAP promoter is that its activity increases in response to extracellular signals that induce reactive gliosis, 18,36,37 or increase intracellular cAMP. 38,39 It is thus likely that transcription from a gfa2-regulated transgene will be stimulated in response to gliosis, generating a feedback mechanism in which an increase in the damage induced by a disease will up-regulate the transcription of the ameliorating transgene.…”

The Predominant Neural Stem Cell Isolated from Postnatal and Adult Forebrain But Not Early Embryonic Forebrain Expresses GFAP

“…GFAP-thymidine kinase (GFAP-TK) transgenic mice were generated previously with a 15 kb promoter cassette that contained the full sequence of the mouse GFAP gene (Bush et al, 1998(Bush et al, , 1999. This cassette (clone 445) contains all introns, promoter regulatory elements, exons, and 2 kb of 3Ј and 2.5 kb of 5Ј flanking regions; expression of GFAP is prevented by removal of a small fragment of the first exon (Johnson et al, 1995). This large and well studied promoter cassette has been used in many laboratories to generate many different lines of mice in which transgene expression has been shown to overlap with endogenous GFAP expression.…”

“…The GFAP-TK transgenic mice used in the present study were generated with a maximal promoter cassette that contained the full sequence of the mouse GFAP gene (Johnson et al, 1995;Bush et al, 1998). Previous evaluation at the single-cell level of these mice showed that 98% of GFAP-expressing cells also expressed TK in the injured forebrain, and that all cells expressing detectable levels of TK also expressed GFAP (Bush et al, 1999).…”

Transgenic inhibition of Nogo-66 receptor function allows axonal sprouting and improved locomotion after spinal injury

“…1A) to allow diffuse CNS secretion from quiescent astrocytes as well as enhanced secretion from reactive astrocytes at site of injury (Johnson et al, 1995). Two NgR(310)ecto-expressing lines were established from five founder mice.…”

“…The mouse NgR(310)ecto cDNA (corresponding to aa 1-310) was subcloned into the NotI site of the C-3123 vector containing the 2.0-kb GFAP promoter, a gift from Dr. Lennart Mucke (Gladstone Institute of Neurological Disease) (Johnson et al, 1995). This construct was released from the pGEM-11Z backbone by sequential digestion with AatII and SfiI, and the resulting 3.4 kb fragment was microinjected into embryos to generate transgenic mice.…”