Faculty Bibliography

Deficient expression of HLA class-I molecules observed in many cancers is suggested to influence both disease progression and potential efficacy of T cell-mediated immune therapy. Previous studies have attempted to correlate either primary breast cancer tumor grade with HLA class-I levels or the presence of HLA class-I-deficient cells in metastatic lesions with survival. In this study we evaluated the HLA class-I status of matched primary and secondary breast cancer lesions in order to ask the question: is metastasis of breast cancer associated with down-regulation of HLA class-I expression? Immunocytochemistry analysis shows a definitive correlation between diminished HLA class-I expression and dissemination of breast cancer to tumor-draining lymph nodes: both the total number of HLA class-I+ cells per sample and the levels of expression are dramatically decreased in secondary versus primary tumor lesions. These findings are consistent with the contention that the ability of breast cancer cells to escape the confines of the original tumor lesion requires down-regulation of HLA class-I expression and implies that enhancing HLA class-I expression in secondary breast cancer may have a beneficial effect on T-cell-mediated immunotherapy

The zona pellucida (ZP) is a thick extracellular coat that surrounds all mammalian eggs. The ZP plays important roles during oogenesis, fertilization, and preimplantation development. The mouse ZP consists of only three glycoproteins, called ZP1, ZP2, and ZP3. All three glycoproteins are essential structural components of the ZP. Additionally, ZP3 serves as a primary sperm receptor and acrosome reaction-inducer, and ZP2 serves as a secondary sperm receptor during fertilization. ZP1, ZP2, and ZP3 are encoded by single-copy genes present on three different chromosomes. The genes are expressed exclusively by mouse oocytes as they grow and the cellular specificity can be ascribed to cis-acting sequences close to the site of transcription initiation and to certain trans-acting factors. Concomitantly, ZP polypeptides are synthesized, modified with N- and O-linked oligosaccharides, secreted, and assembled into crosslinked filaments that exhibit a structural repeat. Nascent ZP glycoproteins are incorporated into large secretory vesicles that fuse with the oocyte plasma membrane and deposit nascent ZP glycoproteins into the innermost layer of the thickening ZP. Each ZP polypeptide possesses several characteristic features, including an N-terminal signal sequence, a ZP domain, a consensus furin cleavage site, and a C-terminal transmembrane domain. The latter is required for assembly of nascent ZP polypeptides into a ZP, cleavage at the consensus furin cleavage site is required for secretion, and the ZP domain supports protein:protein interactions during ZP assembly. At ovulation, when meiotic maturation of oocytes occurs and chromosomes condense into bivalents, expression of the three ZP genes ceases. Using "knockout mice", in the absence of either ZP2 or ZP3 expression, a ZP fails to assemble around growing oocytes and females are infertile. There is no effect on males. In the absence of ZP1 expression, a disorganized ZP assembles around growing oocytes and females exhibit reduced fertility. These observations are consistent with the current model for ZP structure in which ZP2 and ZP3 form long Z filaments crosslinked by ZP1.

A method of creating pseudopure spin states in large clusters of coupled spins is described. It is based on filtering multiple-quantum coherence of the highest order, followed by a time-reversal period and partial saturation. Experimental demonstration is presented for a cluster of six dipolar-coupled proton spins of a benzene molecule in a liquid crystalline matrix, and the details of spin dynamics are studied numerically.

Adenylyl cyclase activity was measured in the striatum of naive mice as a function of age and in mice exposed in utero to cocaine. In naive Swiss-Webster mice, basal and forskolin-stimulated adenylyl cyclase activity increased gradually from embryonic day 13 (E13) until 2-3 weeks of age when activity peaked before decreasing slightly to adult levels. The ability of the dopamine D1 receptor agonist, SKF 82958, to stimulate adenylyl cyclase activity also increased in magnitude until P15. In a separate study, pregnant Swiss-Webster mice were injected twice daily with cocaine (15 mg/kg, s.c.) or an equal volume of saline from E10 to E17. Adenylyl cyclase activity was measured in the striatum of E18 embryos. Basal adenylyl cyclase activity was significantly reduced following prenatal exposure to cocaine. Likewise, the ability of forskolin or SKF 82958 to stimulate adenylyl cyclase was attenuated following cocaine exposure. DeltaFosB was not induced, contrary to what is seen in adult mice. These results demonstrate a functional change in a critical signal transduction pathway following chronic in utero exposure to cocaine that might have profound effects of the development of the brain. Alterations in the cAMP system may underlie some of the deficits seen in humans exposed in utero to cocaine