Identification of the genes up- and down-regulated by the high mobility group A1 (HMGA1) proteins: tissue specificity of the HMGA1-dependent gene regulation.
High mobility group A (HMGA) proteins are chromatinic proteins that do not have transcriptional activity per se, however, by interacting with the transcription machinery, they regulate, negatively or positively, the expression of several genes. We searched for genes regulated by HMGA1 proteins using microarray analysis in embryonic stem (ES) cells bearing one or two disrupted hmga1 alleles. We identified 87 transcripts increased and 163 transcripts decreased of at least 4-fold in hmga1-/- ES cells. For some of them, a HMGA1-dose dependency was observed, because an intermediate level was observed in the heterozygous ES cells. When the expression analysis of these genes was extended to embryonic fibroblasts and adult tissues such as heart, spleen, and liver from hmga1-knockout mice, contrasting results were obtained. In fact, aside some genes showing the same HMGA1 regulation observed in ES cells, there were some genes that did not modify their expression, and others showing a HMGA1-mediated regulation but in an opposite direction. These results clearly indicate that HMGA1-mediated gene regulation depends on the cellular context. Finally for a couple of analyzed HMGA1-regulated genes, electrophoretic mobility shift assay and chromatin immunoprecipitation revealed a direct binding of HMGA1 proteins to their promoters, suggesting a HMGA1-direct regulation of their expression.
Dipartimento di Biologia e Patologia Cellulare e Molecolare e/o Istituto di Endocrinologia ed Oncologia Sperimentale del CNR, Facoltà di Medicina e Chirurgia di Napoli, Università degli Studi di Napoli "Federico II," Naples, Italy.
Josefina
J
Martinez Hoyos
Monica
M
Fedele
Sabrina
S
Battista
Francesca
F
Pentimalli
Mogens
M
Kruhoffer
Claudio
C
Arra
Torben F
TF
Orntoft
Carlo Maria
CM
Croce
Alfredo
A
Fusco
D000818:Animals; D002461:Cell Line, Transformed; D015536:Down-Regulation; D004622:Embryo, Mammalian / Q000166:cytology; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental / Q000235:genetics*; D024003:HMGA Proteins / Q000096:biosynthesis / Q000235:genetics*; D051796:Inhibitor of Differentiation Proteins; D051379:Mice; D018345:Mice, Knockout; D009363:Neoplasm Proteins / Q000235:genetics; D011401:Promoter Regions, Genetic; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013234:Stem Cells / Q000502:physiology*; D015854:Up-Regulation
D024003:HMGA Proteins; D051796:Inhibitor of Differentiation Proteins; D009363:Neoplasm Proteins; C075640:ID3 protein, human