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Robert Benezra

Publications and source records attributed to Robert Benezra.

23 records · Page 2Linked to original sources
PubMed2003

Id-1 is not expressed in the luminal epithelial cells of mammary glands.

BACKGROUND: The family of inhibitor of differentiation/DNA binding (Id) proteins is known to regulate development in several tissues. One member of this gene family, Id-1, has been implicated in mammary development and carcinogenesis. Mammary glands contain various cell types, among which the luminal epithelial cells are primarily targeted for proliferation, differentiation and carcinogenesis. Therefore, to assess the precise significance of Id-1 in mammary biology and carcinogenesis, we examined its cellular localization in vivo using immunohistochemistry. METHODS: Extracts of whole mammary glands from wild type and Id-1 null mutant mice, and tissue sections from paraffin-embedded mouse mammary glands from various developmental stages and normal human breast were subjected to immunoblot and immunohistochemical analyses, respectively. In both these procedures, an anti-Id-1 rabbit polyclonal antibody was used for detection of Id-1. RESULTS: In immunoblot analyses, using whole mammary gland extracts, Id-1 was detected. In immunohistochemical analyses, however, Id-1 was not detected in the luminal epithelial cells of mammary glands during any stage of development, but it was detected in vascular endothelial cells. CONCLUSION: Id-1 is not expressed in the luminal epithelial cells of mammary glands.

Animals↗
PubMed2003

Id proteins in development, cell cycle and cancer.

Id proteins are important parts of signaling pathways involved in development, cell cycle and tumorigenesis. They were first shown to act as dominant negative antagonists of the basic helix-loop-helix family of transcription factors, which positively regulate differentiation in many cell lineages. The Id proteins do this by associating with the ubiquitous E proteins and preventing them from binding DNA or other transcription factors. Id proteins also associate with Ets transcription factors and the Rb family of tumor suppressor proteins, and are downstream targets of transforming growth factor beta and bone morphogenic protein signaling. Thus, the Id proteins have become important molecules for understanding basic biological processes as well as targets for potential therapeutic intervention in human disease.

Aging↗
PubMed2003

Effect of angiogenesis inhibition by Id loss and the contribution of bone-marrow-derived endothelial cells in spontaneous murine tumors.

Angiogenic defects in Id mutant mice inhibit the growth of tumor xenografts, providing a genetic model for antiangiogenic stress. Our work tests the consequences of such stress on progression of more physiological Pten+/- tumors. While tumor growth occurs despite impaired angiogenesis, disruption of vasculature by Id loss causes tumor cells to experience hypoxia and necrosis, the extent of which is tumor dependent. We show that bone-marrow-derived endothelial precursors contribute functionally to neovasculature of some but not all Pten+/- tumors, partially rescuing Id mutant phenotype. We demonstrate that loss of Id1 in tumor endothelial cells results in downregulation of several proangiogenic genes, including alpha6 and beta4 integrins, matrix metalloprotease-2, and fibroblast growth factor receptor-1. Inhibition of these factors phenocopies loss of Id in in vivo angiogenesis assays.

Animals↗
PubMed2001

Enhancer-specific modulation of E protein activity.

Homodimeric complexes of members of the E protein family of basic helix-loop-helix (bHLH) transcription factors are important for tissue-specific activation of genes in B lymphocytes (Bain, G., Gruenwald, S., and Murre, C. (1993) Mol. Cell Biol. 13, 3522-3529; Shen, C. P., and Kadesch, T. (1995) Mol. Cell Biol. 15, 4518-4524; Jacobs, Y., et al. (1994) Mol. Cell Biol. 14, 4087-4096; Wilson, R. B., et al. (1991) Mol. Cell Biol. 11, 6185-6191). These homodimers, however, have little activity on myogenic enhancers (Weintraub, H., Genetta, T., and Kadesch, T. (1994) Genes Dev. 8, 2203-2211). We report here the identification of a novel cis-acting transcriptional repression domain in the E protein family of bHLH transcription factors. This domain, the Rep domain, is present in each of the known vertebrate E proteins. Extensive mapping analysis demonstrates that this domain is an acidic region of 30 amino acids with a predicted loop structure. Fusion studies indicate that the Rep domain can repress both of the E protein transactivation domains (AD1 and AD2). Physiologically, the Rep domain plays a key role in maintaining E protein homodimers in an inactive state on myogenic enhancers. In addition, we demonstrate that Rep domain mediated repression of AD1 is a necessary for the function of MyoD-E protein heterodimeric complexes. These studies demonstrate that the Rep domain is important for modulating the transcriptional activity of E proteins and provide key insights into both the selectivity and mechanism of action of E protein containing bHLH protein complexes.

Amino Acid Sequence↗