Regulation of microRNA expression by HMGA1 proteins.
The High Mobility Group proteins HMGA1 are nuclear architectural factors that play a critical role in a wide range of biological processes. Since recent studies have identified the microRNAs (miRNAs) as important regulators of gene expression, modulating critical cellular functions such as proliferation, apoptosis and differentiation, the aim of our work was to identify the miRNAs that are physiologically regulated by HMGA1 proteins. To this purpose, we have analysed the miRNA expression profile of mouse embryonic fibroblasts (MEFs) carrying two, one or no Hmga1 functional alleles using a microarray (miRNA microarray). By this approach, we found a miRNA expression profile that differentiates Hmga1-null MEFs from the wild-type ones. In particular, a significant decrease in miR-196a-2, miR-101b, miR-331 and miR-29a was detected in homozygous Hmga1-knockout MEFs in comparison with wild-type cells. Consistently, these miRNAs are downregulated in most of the analysed tissues of Hmga1-null mice in comparison with the wild-type mice. ChIP assay shows that HMGA1 is able to bind regions upstream of these miRNAs. Moreover, we identified the HMGA2 gene product as a putative target of miR-196a-2, suggesting that HMGA1 proteins are able to downregulate the expression of the other member of the HMGA family through the regulation of the miR-196a-2 expression. Finally, ATXN1 and STC1 gene products have been identified as targets of miR-101b. Therefore, it is reasonable to hypothesize that HMGA1 proteins are involved in several functions by regulating miRNA expression.
De Martino
I
I
Istituto di Endocrinologia ed Oncologia Sperimentale del CNR c/o Dipartimento di Biologia e Patologia Cellulare e Molecolare, Facoltà di Medicina e Chirurgia di Napoli, Università degli Studi di Napoli Federico II, Naples, Italy.
Visone
R
R
Fedele
M
M
Petrocca
F
F
Palmieri
D
D
Martinez Hoyos
J
J
Forzati
F
F
Croce
C M
CM
Fusco
A
A
D000818:Animals; D000067696:Ataxin-1; D000067528:Ataxins; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D006023:Glycoproteins / Q000235:genetics / Q000502:physiology; D025741:HMGA1a Protein / Q000235:genetics / Q000502:physiology*; D025742:HMGA1b Protein / Q000235:genetics / Q000502:physiology*; D051379:Mice; D035683:MicroRNAs / Q000235:genetics* / Q000502:physiology; D041681:NIH 3T3 Cells; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000502:physiology; D009687:Nuclear Proteins / Q000235:genetics / Q000502:physiology
D000067696:Ataxin-1; D000067528:Ataxins; C000593750:Atxn1 protein, mouse; D006023:Glycoproteins; D035683:MicroRNAs; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D025742:HMGA1b Protein; D025741:HMGA1a Protein; C051795:teleocalcin