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Beta‐cell expression of 65‐kDa heat‐shock protein mRNA is function‐ and age‐dependent
Author(s) -
PEDERSEN C. R.,
JOSEFSEN K.,
BOCK T.,
HANSEN S. V.,
BUSCHARD K.
Publication year - 1992
Publication title -
apmis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.909
H-Index - 88
eISSN - 1600-0463
pISSN - 0903-4641
DOI - 10.1111/j.1699-0463.1992.tb03998.x
Subject(s) - messenger rna , heat shock protein , microbiology and biotechnology , islet , biology , blot , cell sorting , northern blot , beta cell , gene expression , cell culture , rna , insulin , endocrinology , biochemistry , flow cytometry , gene , genetics
This study examined the expression of mRNA coding for the 65‐kDa heat‐shock protein (HSP) in rat islet cells of different functional states and different ages. In addition, beta cells and non‐beta cells purified by fluorescence‐activated cell sorting were studied. Total RNA from islet cells and insulin‐producing RINm5F cells was isolated and analyzed by Northern blotting using a cDNA probe coding for the human homologue to the mycobacterial 65‐kDa HSP, after which blots were quantified by densitometric scanning. Isolated beta cells were found to express 65‐kDa HSP mRNA. The expression was increased in Lewis islet cells exposed to heat shock or high glucose concentration, four‐and three‐fold, respectively (p<0.01). In isolated beta cells cultured at high glucose concentration a doubling in the content of 65‐kDa HSP mRNA was seen compared with islets cultured at low glucose concentration (p<0.05). In islets from Lewis rats fasted for 24 h, the content of 65‐kDa HSP mRNA was 42% lower than in islets isolated from normally fed Lewis rats (p<0.01). Both in BB rats and Wistar Furth rats the content of 65‐kDa HSP mRNA was found to be higher in the 30‐ and the 60‐day‐old rats compared with the neonatal animals (p<0.01). The expression of 65‐kDa HSP mRNA was increased in RINm5F cells following heat shock, while no induction was seen after stimulation with glucose, TPA or IBMX. It is concluded that the 65‐kDa heat‐shock protein belongs to the family of inducible functional antigens in beta cells, which strengthens the interest in 65‐kDa HSP as an antigen possibly involved in the initiation of autoimmune beta‐cell destruction.