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ALTERED CYTOSKELETAL GENE EXPRESSION IN SPACE-FLOWN T CELLS (JURKAT) EVALUATED BY cDNA MICROARRAY AND RT-PCR.  M.L. Lewis¹ and L.A. Cubano².  ¹Dept of Biological Sciences, Univ of Alabama in Huntsville and ²Dept of Medicine, Tulane Univ, New Orleans.

     Cytoskeletal anomalies and inhibition of microtubule polymerization occur in space-flown cells and gravity dependence in microtubule self-organization in cell-free systems was recently demonstrated.  Our shuttle-based research with human leukemic T lymphocytes (Jurkat) consistently shows cytoskeletal disruption and though microtubules appear to reorganize, cells do not grow.  Differences in cytoskeletal gene expression in flown versus ground controls and cells subjected to simulated shuttle launch vibration, can provide insight into gravity-dependent cell function and processes most sensitive to spaceflight.  To test the hypothesis that cytoskeletal gene expression may be altered, we flew Jurkat cells on STS-95 and evaluated genes expressed by cDNA microarray in flown and ground controls at 24 hours (4,324 genes) and 48 hours (>20,000 genes).  Space-flown cells up-regulated messages for eleven cytoskeleton-related genes including calponin, dynactin, tropomodulin, keratin 8, two myosins, an ankyrin EST, an actin-like protein, the cytoskeletal linker (plectin) and a centriole-associated protein (C-NAP1); gelsolin precursor was down-regulated. Up-regulation of message for plectin, which functions in membrane-cytoskeletal association, filament elongation, and inter-filament integrity and C-NAP1 in both space-flown and simulated launch vibrated cells implies their role in vibration damage repair.  Unlike flown cells, vibrated cells resumed growth thus growth arrest during spaceflight is not a primary result of shuttle launch vibration.  Microgravity per se or other orbit-related factors appear to affect cytoskeletal gene expression and cell growth.  Based on differential expression of cytoskeletal genes, we conclude that centriole-centriole, membrane-cytoskeletal, and cytoskeletal filament associations and their related cellular functions are altered during the orbital phase of spaceflight. 

     (Partial support: NASA Grant NAG2-985)