Intron 1 GATA site enhances ALAS2 expression indispensably during erythroid differentiation

Nucleic Acids Res. 2017 Jan 25;45(2):657-671. doi: 10.1093/nar/gkw901. Epub 2016 Oct 7.


The first intronic mutations in the intron 1 GATA site (int-1-GATA) of 5-aminolevulinate synthase 2 (ALAS2) have been identified in X-linked sideroblastic anemia (XLSA) pedigrees, strongly suggesting it could be causal mutations of XLSA. However, the function of this int-1-GATA site during in vivo development remains largely unknown. Here, we generated mice lacking a 13 bp fragment, including this int-1-GATA site (T AGATAA: AGCCCC) and found that hemizygous deletion led to an embryonic lethal phenotype due to severe anemia resulting from a lack of ALAS2 expression, indicating that this non-coding sequence is indispensable for ALAS2 expression in vivo Further analyses revealed that this int-1-GATA site anchored the GATA site in intron 8 (int-8-GATA) and the proximal promoter, forming a long-range loop to enhance ALAS2 expression by an enhancer complex including GATA1, TAL1, LMO2, LDB1 and Pol II at least, in erythroid cells. However, compared with the int-8-GATA site, the int-1-GATA site is more essential for regulating ALAS2 expression through CRISPR/Cas9-mediated site-specific deletion. Therefore, the int-1-GATA site could serve as a valuable site for diagnosing XLSA in cases with unknown mutations.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5-Aminolevulinate Synthetase / genetics*
  • Anemia, Sideroblastic / genetics
  • Animals
  • Base Sequence
  • Binding Sites*
  • CRISPR-Cas Systems
  • Cell Differentiation*
  • Disease Models, Animal
  • Enhancer Elements, Genetic
  • Erythroid Cells / cytology*
  • Erythroid Cells / metabolism*
  • GATA1 Transcription Factor / metabolism*
  • Gene Expression Regulation
  • Genes, Lethal
  • Genetic Diseases, X-Linked / genetics
  • Hematopoietic Stem Cells / cytology
  • Hematopoietic Stem Cells / metabolism
  • Hemizygote
  • Humans
  • Introns*
  • K562 Cells
  • Male
  • Mutation
  • Pedigree
  • Promoter Regions, Genetic
  • Sequence Deletion


  • GATA1 Transcription Factor
  • 5-Aminolevulinate Synthetase
  • ALAS2 protein, human

Supplementary concepts

  • X-linked sideroblastic anemia