The Human Achaete Scute Homolog 2 gene contains two promotors, generating overlapping transcripts and encoding two proteins with different nuclear localization

B A Westerman, A Poutsma, L H Looijenga, D Wouters, I J van Wijk, C B Oudejans

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21 Citations (Scopus)


Placental development involves control by the basic helix-loop-helix transcription factor Mash2. Transcript analysis of the Human Achaete Scute Homolog 2 (HASH2) mRNA revealed the presence of two overlapping transcripts in first trimester placentae. The two transcripts (2.6 and 1.5 kb) are generated by two promotors which are separated by 1.1 kb, generating transcripts 1 and 2, respectively. Surprisingly, in transcript 1 which shows a broad expression, a second potential coding region, tentatively called Human Achaete Scute Associated Protein (HASAP) was present. Transcript 2 contains the HASH2 encoding region only. Analysis of protein expression from both transcripts by transfection studies with eGFP fusion proteins, revealed that both coding regions are translated from their endogenous translation initiation site and showed that both proteins are transported to the nucleus. HASH2 is distributed throughout the nucleus but the HASAP protein is transported into nuclear compartments, the nucleoli. In addition, the HASAP protein lacks the bHLH domain and bears no homology to known proteins. Moreover, allele-specific RT-PCR showed the human gene not to be subject to imprinting, possibly reflecting the biallelic expression of one of both transcripts. Our data indicate a species-specific difference between mouse and human expression of the Achaete Scute Homolog 2 and suggests a dual function of the human homologue.

Original languageEnglish
Pages (from-to)511-8
Number of pages8
Issue number6
Publication statusPublished - Jul 2001


  • Alleles
  • Animals
  • Basic Helix-Loop-Helix Transcription Factors
  • Cell Line
  • Cell Nucleus/chemistry
  • DNA-Binding Proteins/analysis
  • Female
  • Gene Expression
  • Green Fluorescent Proteins
  • Humans
  • Luminescent Proteins/genetics
  • Mice
  • Placenta/chemistry
  • Pregnancy
  • Pregnancy Trimester, First
  • Promoter Regions, Genetic
  • RNA, Messenger/analysis
  • Recombinant Fusion Proteins
  • Reverse Transcriptase Polymerase Chain Reaction
  • Species Specificity
  • Transcription Factors
  • Transfection

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