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Changes in gene expression and signal transduction in microgravityStudies from space flights over the past three decades have demonstrated that basic physiological changes occur in humans during space flight. These changes include cephalic fluid shifts, loss of fluid and electrolytes, loss of muscle mass, space motion sickness, anemia, reduced immune response, and loss of calcium and mineralized bone. The cause of most of these manifestations is not known and until recently, the general approach was to investigate general systemic changes, not basic cellular responses to microgravity. This laboratory has recently studied gene growth and activation of normal osteoblasts (MC3T3-El) during spaceflight. Osteoblast cells were grown on glass coverslips and loaded in the Biorack plunger boxes. The osteoblasts were launched in a serum deprived state, activated in microgravity and collected in microgravity. The osteoblasts were examined for changes in gene expression and signal transduction. Approximately one day after growth activation significant changes were observed in gene expression in 0-G flight samples. Immediate early growth genes/growth factors cox-2, c-myc, bcl2, TGF beta1, bFGF and PCNA showed a significant diminished mRNA induction in microgravity FCS activated cells when compared to ground and 1-G flight controls. Cox-1 was not detected in any of the samples. There were no significant differences in the expression of reference gene mRNA between the ground, 0-G and 1-G samples. The data suggest that quiescent osteoblasts are slower to enter the cell cycle in microgravity and that the lack of gravity itself may be a significant factor in bone loss in spaceflight. Preliminary data from our STS 76 flight experiment support our hypothesis that a basic biological response occurs at the tissue, cellular, and molecular level in 0-G. Here we examine ground-based and space flown data to help us understand the mechanism of bone loss in microgravity.
Document ID
20040102090
Acquisition Source
Ames Research Center
Document Type
Reprint (Version printed in journal)
Authors
Hughes-Fulford, M.
(Department of Veteran's Affairs Medical Center and University of California San Fransico CA 94121, United States)
Date Acquired
August 21, 2013
Publication Date
July 1, 2001
Publication Information
Publication: Journal of gravitational physiology : a journal of the International Society for Gravitational Physiology
Volume: 8
Issue: 1
ISSN: 1077-9248
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: NAG2-1286
CONTRACT_GRANT: NAG2-1086
Distribution Limits
Public
Copyright
Other
Keywords
manned
Non-NASA Center
STS-76 Shuttle Project
Flight Experiment
NASA Discipline Cell Biology
NASA Experiment Number 9403056
short duration

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