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Biomedical subjects

W R Brinkley

Publications and source records attributed to W R Brinkley.

6 recordsLinked to original sources
PubMed2007

Loss of chromosomal integrity drives rat mammary tumorigenesis.

Breast cancer incidence varies with diet and other environmental influences, including carcinogen exposure. However, the effects of carcinogens on cell growth control pathways are poorly understood. Here, we have examined processes that are activated in the mammary glands of rats treated with 1-methyl-1-nitrosourea (MNU). This synthetic carcinogen was used to study events occurring during mammary tumor initiation and development. In female Wistar-Furth rats, given 1 dose of MNU beginning at 50 days of age, 84% of the rats developed tumors by 46 weeks of age (latency 13-15 weeks). Changes in the gland occurred as early as 1-day post-MNU. Cells exhibited DNA damage, leading to chromosomal instability, supernumerary centrosomes and higher levels of Aurora A; these events correlated with the appearance of preneoplasia in the glands. In mammary tumors, elevated numbers of centrosomes coincided with genomic instability. Tumors were transplanted into syngeneic hosts and subsequent tumor generations displayed the same marker chromosomes in mostly aneuploid metaphases with hyperdiploid numbers of chromosomes, suggesting that clonality and aneuploidy were passed on from one generation to the next. Collectively, these data suggest that the carcinogen MNU induces changes resulting in genetic instability detectable before hyperplasia and tumors develop in the rat mammary gland.

Animals↗
PubMed2000

The subcellular localization of acetyl-CoA carboxylase 2.

Animals, including humans, express two isoforms of acetyl-CoA carboxylase (EC ), ACC1 (M(r) = 265 kDa) and ACC2 (M(r) = 280 kDa). The predicted amino acid sequence of ACC2 contains an additional 136 aa relative to ACC1, 114 of which constitute the unique N-terminal sequence of ACC2. The hydropathic profiles of the two ACC isoforms generally are comparable, except for the unique N-terminal sequence in ACC2. The sequence of amino acid residues 1-20 of ACC2 is highly hydrophobic, suggesting that it is a leader sequence that targets ACC2 for insertion into membranes. The subcellular localization of ACC2 in mammalian cells was determined by performing immunofluorescence microscopic analysis using affinity-purified anti-ACC2-specific antibodies and transient expression of the green fluorescent protein fused to the C terminus of the N-terminal sequences of ACC1 and ACC2. These analyses demonstrated that ACC1 is a cytosolic protein and that ACC2 was associated with the mitochondria, a finding that was confirmed further by the immunocolocalization of a known human mitochondria-specific protein and the carnitine palmitoyltransferase 1. Based on analyses of the fusion proteins of ACC-green fluorescent protein, we concluded that the N-terminal sequences of ACC2 are responsible for mitochondrial targeting of ACC2. The association of ACC2 with the mitochondria is consistent with the hypothesis that ACC2 is involved in the regulation of mitochondrial fatty acid oxidation through the inhibition of carnitine palmitoyltransferase 1 by its product malonyl-CoA.

Acetyl-CoA Carboxylase↗
PubMed1995

The C terminus of mitosin is essential for its nuclear localization, centromere/kinetochore targeting, and dimerization.

Mitosin is a novel 350-kDa nuclear phosphoprotein that dramatically relocates from the evenly nuclear distribution in S phase to the centromere/kinetochore and mitotic apparatus in M phase. The dynamic relocalization of mitosin is accompanied by the phosphorylation of itself, suggesting that mitosin plays a role in mitotic progression. The molecular basis of nuclear localization and targeting of mitosin to the centromere/kinetochore were characterized using a set of epitope-tagged deletion mutants. The data indicate that the extreme C terminus (amino acids 2,487-3,113) of mitosin has both an independent centromere/kinetochore targeting domain and an unusually spaced bipartite nuclear localization signal. Moreover, the same centromere/kinetochore targeting domain was shown to be essential for the ability of mitosin to bind to itself or other putative mitosin-associated proteins through use of the yeast two-hybrid system. These results suggest that the C terminus of the mitosin is essential for its role in influencing cell cycle progression.

Amino Acid Sequence↗