Complex cardiac Nkx2-5 gene expression activated by noggin-sensitive enhancers followed by chamber-specific modules

Proc Natl Acad Sci U S A. 2005 Sep 20;102(38):13490-5. doi: 10.1073/pnas.0504295102. Epub 2005 Sep 6.

Abstract

We previously reported that an Nkx2-5-GFP bacterial artificial chromosome in transgenic mice recapitulated the endogenous gene activity in the heart. Here, we identified three additional previously uncharacterized distal enhancer modules of Nkx2-5: UH6, which directed transgene expression in the right ventricle, interventricular septum, and atrial ventricular canal; UH5, which directed expression in both atria; and UH4, which directed transgene expression in tongue muscle. Nkx2-5 enhancers drive cardiogenic gene activity from the earliest progenitors to the late-stage embryonic heart, reside within its 27 kb of 5' flanking sequences, organized in a tandem array. Nkx2-5 enhancers involved with stomach-, tongue-, and chamber-restricted expression displayed lacZ transgene activity and chromatin histone acetylation patterns consistent with tissue-specific expression. An examination of Nkx2-5 gene activity in murine embryonic stem cells converted to beating embryoid bodies showed that only the proximal active region 2 and GATA-Smad enhancers were chromatin-remodeled. Chromatin remodeling of active region 2 and GATA-Smad enhancers were blunted by noggin coexpression, which indicated dependence on bone morphogenetic protein signaling for their chromatin activation during activation of Nkx2-5 expression.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Bone Morphogenetic Proteins / metabolism
  • Carrier Proteins / metabolism*
  • Cells, Cultured
  • Chromatin Assembly and Disassembly / genetics
  • Chromosomes, Artificial, Bacterial / genetics
  • Embryo, Mammalian / cytology
  • Embryo, Mammalian / physiology
  • Enhancer Elements, Genetic / physiology*
  • Gene Expression Regulation, Developmental / genetics*
  • Heart Atria / embryology
  • Heart Ventricles / embryology
  • Homeobox Protein Nkx-2.5
  • Homeodomain Proteins / biosynthesis*
  • Homeodomain Proteins / genetics
  • Mice
  • Mice, Transgenic
  • Organ Specificity / genetics
  • Signal Transduction / genetics
  • Stem Cells / cytology
  • Stem Cells / metabolism
  • Tongue / embryology
  • Transcription Factors / biosynthesis*
  • Transcription Factors / genetics
  • Transgenes / physiology

Substances

  • Bone Morphogenetic Proteins
  • Carrier Proteins
  • Homeobox Protein Nkx-2.5
  • Homeodomain Proteins
  • Nkx2-5 protein, mouse
  • Transcription Factors
  • noggin protein