Gravitational loading of a simulated launch alters mRNA expression in osteoblasts.
Serum-deprived mouse osteoblastic cells (MC3T3-E1a) were centrifuged under a regime designed to simulate a space shuttle launch (maximum of 3g). Messenger RNA levels for eight genes involved in bone growth and maintenance were determined using RT-PCR. Following 30 min of centrifugation, mRNA level for early response gene c-fos was significantly increased 89% (P < 0.05). The c-fos induction was transient and returned to control levels after 3 h. The mRNA level for the mineralization marker gene osteocalcin was significantly decreased to 44% of control level (P < 0.005) 3 h after centrifugation. No changes in mRNA levels were detected for c-myc, TGFbeta1, TGFbeta2, cyclophilin A, or actin. No basal mRNA level for TGFbeta3 was detected. In addition, no change in the steady-state synthesis of prostaglandin E2 was detected, possibly due to lack of lipid substrates in serum-deprived cells, suggesting that the increase in c-fos mRNA in response to gravitational loading is a result of mechanical stimulation. These results indicate that a small magnitude mechanical loading, such as that experienced during a shuttle launch, can alter mRNA levels in quiescent osteoblastic cells.
Department of Medicine, Veterans Affairs Medical Center, University of California, San Francisco 94121, USA.
J
J
Fitzgerald
M
M
Hughes-Fulford
D000199:Actins / Q000235:genetics; D000591:Amino Acid Isomerases / Q000235:genetics; D000818:Animals; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D002455:Cell Division / Q000235:genetics; D002460:Cell Line; D017931:DNA Primers / Q000235:genetics; D015232:Dinoprostone / Q000096:biosynthesis; D015870:Gene Expression; D016762:Genes, fos; D016259:Genes, myc; D018471:Hypergravity / Q000009:adverse effects*; D051379:Mice; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D015675:Osteocalcin / Q000235:genetics; D019696:Peptidylprolyl Isomerase; D012333:RNA, Messenger / Q000235:genetics* / Q000378:metabolism*; D013026:Space Flight; D016212:Transforming Growth Factor beta / Q000235:genetics
D000199:Actins; D002352:Carrier Proteins; D017931:DNA Primers; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D015675:Osteocalcin; D000591:Amino Acid Isomerases; D019696:Peptidylprolyl Isomerase; D015232:Dinoprostone