Distinct regions control transcriptional activation of the alpha1(VI) collagen promoter in different tissues of transgenic mice.

Abstract

Abstract. To identify regions involved in tissue specific regulation of transcription of the a l (VI) collagen chain, transgenic mice were generated carrying various portions of the gene's 5'-flanking sequence fused to the E. coli 13-galactosidase gene. Analysis of the transgene expression pattern by X-gal staining of embryos revealed that: (a) The proximal 0.6 kb of promoter sequence activated transcription in mesenchymal cells at sites of insertion of superficial muscular aponeurosis into the skin; tendons were also faintly positive. (b) The region between -4.0 and -5.4 kb from the transcription start site was required for activation of the transgene in nerves. It also drove expression in joints, in intervertebral disks, and in subepidermal and vibrissae mesenchyme. (c) The fragment comprised within -6.2 and -7.5 kb was necessary for high level transcription in skeletal muscle and meninges. Positive cells in muscle were mostly mononuclear and probably included connective tissue elements, although staining of myoblasts was not ruled out. This fragment also activated expression in joints, in intervertebral disks, and in subepidermal and vibrissae mesenchyme. (d) [3-Galactosidase staining in vibrissae induced by the sequences -4.0 to -5.4 and -6.2 to -7.5 was not coincident: with the latter sequence labeled nuclei were found mainly in the ventral and posterior quadrant, and, histologically, in the outer layers of mesenchyme surrounding and between the follicles, whereas with the former the remaining quadrants were positive and expressing cells were mostly in the inner layers of the dermal sheath. (e) Other tissues, notably lung, adrenal gland, digestive tract, which produce high amounts of collagen type VI, did not stain for 13-galactosidase. (f) Central nervous system and retina, in which the endogenous gene is inactive, expressed the lacZ transgene in most lines. The data suggest that transcription of al(VI) in different tissues is regulated by distinct sequence elements in a modular arrangement, a mechanism which confers high flexibility in the temporal and spatial pattern of expression during development.

Collagen VI at a glance

“…In the peripheral nervous system, ColVI is abundantly expressed by Schwann cells and is present in the connective tissue of the endo-, peri-and epineurium (Braghetta et al, 1996;Chen et al, 2014a). It has been shown previously that ColVI has a role in regulating Schwann cell differentiation because it is expressed by immature Schwann cells in a neuregulin-dependent manner when they start differentiating into myelinating cells (Vitale et al, 2001).…”

Mitochondrial Dysfunction and Defective Autophagy in the Pathogenesis of Collagen VI Muscular Dystrophies

“…Studies in transfected cells and in transgenic mice demonstrated that transcriptional regulation is the major determinant for the highly regulated and dynamic pattern expression of ColVI during development and in adult tissues. The data thus far available for the Col6a1 gene indicate a complex pattern of tissue-specific transcription that is dependent on different enhancer and silencer elements spread over a large genomic region and controlling expression in skin, tendons, joints, peripheral nerves, and skeletal muscles, respectively (Braghetta et al 1996). Muscle interstitial fibroblasts are the main source of ColVI in the ECM of skeletal muscle .…”

Lentiviral-mediated RNAi in vivo silencing of Col6a1, a gene with complex tissue specific expression pattern

“…As most of the extracellular matrix components, collagen VI is endowed with exquisite systems of tissue specific transcriptional regulation (Braghetta et al, 1996). This condition adds to the complexity of inhibiting the expression of the Col6a1 gene in vivo by RNAi.…”

“…Information on the regulation of expression of collagen VI comes from studies on the ␣1(VI) chain (Braghetta et al, 1996Fabbro et al, 1999;Girotto et al, 2000;Vitale et al, 2001). Regulation is mainly achieved through different enhancers, each of which controls transcription only in a limited set tissues.…”