Patterns of spectrin transcripts in erythroid and non-erythroid cells.
Spectrin is the major protein of the membrane erythrocyte skeleton. More recently, homologous but non-identical spectrins (fodrins) were also found in various non-erythroid tissues. Spectrin mRNA in erythroid and various non-erythroid cells was examined by direct hybridization with human alpha-spectrin, beta-spectrin (erythroid spectrins), and alpha-fodrin (non-erythroid spectrin) cDNA probes. Northern blot analysis of poly (A)+ RNA revealed a distinct pattern of expression in erythroid vs. non-erythroid cells. Erythroid cells from early erythroblasts to reticulocyte stage expressed two mRNA species of beta-spectrin, whereas they expressed only a single species of alpha-spectrin, and no alpha-fodrin mRNA. In contrast, non-erythroid cells (platelets, myeloid cells, liver, muscle, heart, cerebellum, and eye lens) expressed either no alpha-spectrin mRNA or a different molecular weight transcript(s) of this gene, and a single species of alpha-fodrin mRNA. Additionally, they also expressed from none to multiple species of beta-spectrin, and these were of different molecular size(s) from that found in erythroid cells (with the exception of platelets). Transcripts of non-erythroid spectrin, alpha-fodrin, were found as a single copy only in non-erythroid tissues. Human and murine erythroleukemia cells expressed both erythroid spectrin transcripts in addition to alpha-fodrin and raise the possibility that erythroid progenitors may have the potential to express both erythroid and non-erythroid species. These data indicated that several mRNA species of beta-spectrin could be detected in both erythroid and some non-erythroid cells. Whether multiple spectrin peptides could also be found with functional heterogeneity is unclear. However, in each case, the pattern combination observed appeared to be tissue-specific.
Division of Hematology, University of Alabama, Birmingham 35294.
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Prchal
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Papayannopoulou
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Yoon
D015152:Blotting, Northern; D002460:Cell Line; D004900:Erythroblasts / Q000378:metabolism*; D006801:Humans; D007938:Leukemia; D004915:Leukemia, Erythroblastic, Acute; D009693:Nucleic Acid Hybridization; D011061:Poly A / Q000097:blood / Q000235:genetics*; D012313:RNA / Q000097:blood / Q000235:genetics*; D012333:RNA, Messenger / Q000097:blood / Q000235:genetics*; D012156:Reticulocytes / Q000378:metabolism*; D013049:Spectrin / Q000235:genetics*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured / Q000378:metabolism*
D012333:RNA, Messenger; D013049:Spectrin; D011061:Poly A; D012313:RNA