Prothymosin α mRNA is expressed in competent and proliferating rat thyroid cells (FRTL-5) but is not sufficient to elicit cell progression through the cell cycle

in Journal of Molecular Endocrinology
Authors:
C V Alvarez
Search for other papers by C V Alvarez in
Current site
Google Scholar
PubMed
Close
,
J B Zalvide
Search for other papers by J B Zalvide in
Current site
Google Scholar
PubMed
Close
,
E Cancio
Search for other papers by E Cancio in
Current site
Google Scholar
PubMed
Close
,
C Dieguez
Search for other papers by C Dieguez in
Current site
Google Scholar
PubMed
Close
,
B J Regueiro
Search for other papers by B J Regueiro in
Current site
Google Scholar
PubMed
Close
,
F V Vega
Search for other papers by F V Vega in
Current site
Google Scholar
PubMed
Close
, and
F Dominguez
Search for other papers by F Dominguez in
Current site
Google Scholar
PubMed
Close
View More View Less
Restricted access

USD  $0.01
USD  $0.01

USD  $0.01
USD  $0.01

USD  $0.01
USD  $0.01

USD  $0.01
USD  $0.01

USD  $0.01
USD  $0.01

USD  $0.01
USD  $0.01

USD  $0.01
USD  $0.01

USD  $0.01
USD  $0.01

USD  $0.01
USD  $0.01

USD  $1.00
USD  $1.00

USD  $1.00
USD  $1.00

USD  $1.00
USD  $1.00

ABSTRACT

Using flow cytometry we observed the effects that different hormonal treatments had on the progression of rat thyroid (FRTL-5) cells through the cell cycle. The absence of hormones or the addition of TSH (6 mU/ml) did not induce DNA synthesis; however, the addition of IGF-I (30 ng/ml) promoted cell proliferation. The number of cells recruited by IGF-I was lower than when IGF-I and TSH were used. We therefore concluded that we had a model with three different types of cells: (1) quiescent cells, cells cultured in the absence of hormones, considered to be G0-arrested cells, (2) competent cells, TSH-treated cells that did not proliferate (being arrested in a cycle phase different from G0) and (3) actively proliferating cells, cells treated with TSH plus IGF-I.

Prothymosin α (PTA) mRNA levels were almost undetectable in cells cultured without hormones at all times studied, i.e. 8, 14 and 24 h. On the contrary, TSH and/or IGF-I greatly increased PTA mRNA. These data indicate that G0-arrested quiescent cells do not express PTA mRNA and that PTA mRNA is induced when FRTL-5 cells are committed to proliferate by the addition of TSH, in spite of being arrested by the lack of IGF-I. We therefore conclude that PTA mRNA expression may be an event that is necessary for cells to proliferate, but that it is not sufficient for the promotion of cell progression through the cell cycle.

 

  • Collapse
  • Expand