Expression of the small heat shock protein alphaB-crystallin in term human placenta.
OBJECTIVE
Expression of heat shock proteins has been described in different tissues relevant to human reproduction, including placenta. AlphaB-crystallin is a member of the small heat shock protein family (sHsp) exerting biologically important chaperon functions.


METHODS
Immunofluorescence; immunoblot analysis; quantitative real-time-PCR; CpG island methylation analysis.


RESULTS
In this study, we once again describe the expression of alphaB-crystallin in the stroma of the placental villi and in the cytoplasm of decidual cells by immunofluorescence. In contrast, Hsp27--another sHsp family member--was detected exclusively in the syncytiotrophoblast layer. This varying expression pattern provides additional support to earlier reports of functional differences between both proteins. Semi-quantitative immunoblot analysis of placenta tissue specimens (n = 6) revealed Hsp27 expression exceeding that of alphaB-crystallin, albeit with interindividual variations. Inter-individual alphaB-crystallin expression variations were confirmed by quantitative RT-PCR. CpG island methylation was ruled out as the underlying cause for the inter-individual alphaB-crystallin expression variations. However, the expression extent of GATA3, which is a transcription factor with corresponding elements within the alphaB-crystallin gene (CRYAB) promoter, paralleled that of alphaB-crystallin. We demonstrated remarkable GATA3 expression in placental tissue, exceeding that of other endocrine organs.


CONCLUSIONS
We can conclude that the differential expression patterns of alphaB-crystallin and Hsp27 indicate functional differences between these highly related proteins in placental tissues.
Mineva
Ivelina
I
Institute of Biology and Immunology of Reproduction, Bulgarian Academy of Sciences, Sofia, Bulgaria. imineva@abv.bg
Stamenova
Maria
M
Gartner
Wolfgang
W
Wagner
Ludwig
L
D018899:CpG Islands / Q000235:genetics; D019175:DNA Methylation / Q000235:genetics; D005260:Female; D050990:GATA3 Transcription Factor / Q000378:metabolism*; D005786:Gene Expression Regulation; D055551:HSP27 Heat-Shock Proteins / Q000096:biosynthesis* / Q000235:genetics; D006801:Humans; D010920:Placenta / Q000166:cytology / Q000378:metabolism*; D038203:alpha-Crystallin B Chain / Q000096:biosynthesis* / Q000235:genetics
D050990:GATA3 Transcription Factor; C494749:GATA3 protein, human; D055551:HSP27 Heat-Shock Proteins; D038203:alpha-Crystallin B Chain