Abstract
Transcription factor Lbx1 is known to play a role in the migration of muscle progenitor cells in limb buds and also in neuronal determination processes. In addition, involvement of Lbx1 in cardiac neural crest-related cardiogenesis was postulated. Here, we used mouse embryonic stem (ES) cells which have the capacity to develop into cells of all three primary germ layers. During in vitro differentiation, ES cells recapitulate cellular developmental processes and gene expression patterns of early embryogenesis. Transcript analysis revealed a significant upregulation of Lbx1 at the progenitor cell stage. Immunofluorescence staining confirmed the expression of Lbx1 in skeletal muscle cell progenitors and GABAergic neurons. To verify the presence of Lbx1 in cardiac cells, triple immunocytochemistry of ES cell-derived cardiomyocytes and a quantification assay were performed at different developmental stages. Colabeling of Lbx1 and cardiac specific markers troponin T, α-actinin, GATA4, and Nkx2.5 suggested a potential role in early myocardial development.
Highlights
Lbx1 is a member of the Ladybird-like homeobox gene family that encodes a homeodomain transcription factor
Analysis of Lbx1 at the transcript and protein level in embryonic stem (ES) cell-derived progeny revealed the expression in neurons as well as skeletal muscle progenitors and in a small subpopulation of cardiomyocytes
This is the first time that a coexpression of Lbx1 and several cardiacspecific markers could be demonstrated in ES cell-derived cardiomyocytes
Summary
Lbx is a member of the Ladybird-like homeobox gene family that encodes a homeodomain transcription factor. Expression of Lbx has been described in the CNS and in migrating muscle precursor cells. During early mouse embryonic development, the presence or absence of Lbx distinguishes two major neuronal classes generated in the dorsal spinal cord [2]. Lbx is essential for determining a somatosensory instead of a viscerosensory fate in relay neurons in the hindbrain [3]. At later stages of mouse neurogenesis, expression of Lbx defines a basal GABAergic differentiation state for dorsal horn neurons [4]
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