Transcriptional and translational regulation of β-cell differentiation factor Nkx6.1

Hirotaka Watada, Raghu Mirmira, Joey Leung, Michael S. German

Research output: Contribution to journalArticle

57 Citations (Scopus)

Abstract

In the mature pancreas, the homeodomain transcription factor Nkx6.1 is uniquely restricted to β-cells. Nkx6.1 also is expressed in developing β-cells and plays an essential role in their differentiation. Among cell lines, both β- and α-cell lines express nkx6.1 mRNA; but no protein can be detected in the α-cell lines, suggesting that post-transcriptional regulation contributes to the restriction of Nkx6.1 to β-cells. To investigate the regulator of Nkx6.1 expression, we outlined the structure of the mouse nkx6.1 gene, and we identified regions that direct cell type-specific expression. The nkx6.1 gene has a long 5'-untranslated region (5'-UTR) downstream of a cluster of transcription start sites. nkx6.1 gene sequences from -5.6 to +1.0 kilobase pairs have specific promoter activity in β-cell lines but not in NIH3T3 cells. This activity is dependent on sequences located at about -800 base pairs and on the 5'-UTR. Electrophoretic mobility shift assays demonstrate that homeodomain transcription factors PDX1 and Nkx2.2 can bind to the sequence element located at -800 base pairs. In addition, dicistronic assays establish that the 5'-UTR region functions as a potent internal ribosomal entry site, providing cell type-specific regulation of translation. These data demonstrate that complex regulation of both Nkx6.1 transcription and translation provides the specificity of expression required during pancreas development.

Original languageEnglish (US)
Pages (from-to)34224-34230
Number of pages7
JournalJournal of Biological Chemistry
Volume275
Issue number44
StatePublished - Nov 3 2000
Externally publishedYes

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Cell Differentiation
5' Untranslated Regions
Cells
Genes
Cell Line
Assays
Transcription Factors
Base Pairing
Electrophoretic mobility
Pancreas
Transcription Initiation Site
Transcription
Electrophoretic Mobility Shift Assay
Messenger RNA
Proteins

ASJC Scopus subject areas

  • Biochemistry

Cite this

Transcriptional and translational regulation of β-cell differentiation factor Nkx6.1. / Watada, Hirotaka; Mirmira, Raghu; Leung, Joey; German, Michael S.

In: Journal of Biological Chemistry, Vol. 275, No. 44, 03.11.2000, p. 34224-34230.

Research output: Contribution to journalArticle

Watada, Hirotaka ; Mirmira, Raghu ; Leung, Joey ; German, Michael S. / Transcriptional and translational regulation of β-cell differentiation factor Nkx6.1. In: Journal of Biological Chemistry. 2000 ; Vol. 275, No. 44. pp. 34224-34230.
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