Biomedical subjects

Lubov Nathanson

Publications and source records attributed to Lubov Nathanson.

4 recordsLinked to original sources

PubMed2005

Microarray analysis of gene expression in adult retinal ganglion cells.

Retinal ganglion cells (RGCs) transfer visual information to the brain and are known to be susceptible to selective degeneration in various neuropathies such as glaucoma. This selective vulnerability suggests that these highly specialized neurons possess a distinct gene expression profile that becomes altered by neuropathy-associated stresses, which lead to the RGC death. In this study, to identify genes expressed predominantly in adult RGCs, a global transcriptional profile of purified primary RGCs has been compared to that of the whole retina. To avoid alterations of the original gene expression profile by cell culture conditions, we isolated RNA directly from adult RGCs purified by immunopanning without prior sub-cultivation. Genes expressed predominantly in RGCs included: Nrg1, Rgn, 14-3-3 family (Ywhah, Ywhaz, Ywhab), Nrn1, Gap43, Vsnl1, Rgs4. Some of these genes may serve as novel markers for these neurons. Our analysis revealed enrichment in genes controlling the pro-survival pathways in RGCs as compared to other retinal cells.

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PubMed2005

Microarray analysis of fiber cell maturation in the lens.

The mammalian lens consists of an aged core of quiescent cells enveloped by layers of mature fully elongated cells and younger, continuously elongating transcriptionally active cells. The fiber cell maturation is initiated when fiber cells cease to elongate. The process of maturation represents a radical switch from active elongation to a life-long quiescence and has not been studied previously. It may also include critical stages of preparation for the organelle removal and denucleation. In the present study, we used laser capture microdisection (LCM) microdissection and RNA amplification to compare global gene expression profiles of young elongating and mature, non-elongating fiber cells. Analysis of microarray data from three independent dye-swap experiments identified 65 differentially expressed genes (FDR<0.1) with greater than 2-fold change in expression levels. Microarray array results for a group of randomly selected genes were confirmed by quantitative RT-PCR. These microarray results provide clues to understanding the molecular pathways underlying lens development. The identified changes in the profile of gene expression reflected a shift in cell physiology characterizing the lens fiber maturation.

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PubMed2003

Organization of mammalian cytoplasm.

Although the role of macromolecular interactions in cell function has attracted considerable attention, important questions about the organization of cells remain. To help clarify this situation, we used a simple protocol that measures macromolecule release after gentle permeabilization for the examination of the status of endogenous macromolecules. Treatment of Chinese hamster ovary cells with saponin under carefully controlled conditions allowed entry of molecules of at least 800 kDa; however, there were minimal effects on internal cellular architecture and protein synthesis remained at levels comparable to those seen with intact cells. Most importantly, total cellular protein and RNA were released from these cells extremely slowly. The release of actin-binding proteins and a variety of individual cytoplasmic proteins mirrored that of total protein, while marker proteins from subcellular compartments were not released. In contrast, glycolytic enzymes leaked rapidly, indicating that cells contain at least two distinct populations of cytoplasmic proteins. Addition of microfilament-disrupting agents led to rapid and extensive release of cytoplasmic macromolecules and a dramatic reduction in protein synthesis. These observations support the conclusion that mammalian cells behave as highly organized, macromolecular assemblies (dependent on the actin cytoskeleton) in which endogenous macromolecules normally are not free to diffuse over large distances.

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PubMed2003

Nuclear protein synthesis: a re-evaluation.

It has been reported that nuclei from HeLa cells are responsible for approximately 10%-15% of total cellular protein synthesis. We show here that isolated Chinese hamster ovary (CHO) and HeLa cell nuclei are essentially inactive for translation, and that the earlier results were most likely due to cytoplasmic contamination. Moreover, we suggest that the nascent polypeptides observed in nuclei of permeabilized cells may have been due to "overpermeabilization" and consequent damage to the cells. Based on this information, we conclude that nuclear protein synthesis, if it exists, is limited to less than 1% of that in cells.

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