Neural stem/progenitor cells express 20 tenascin C isoforms that are differentially regulated by Pax6.
Tenascin C (Tnc) is an alternatively spliced, multimodular extracellular matrix glycoprotein present in the ventricular zone of the developing brain. Pax6-deficient small eye (sey) mouse mutants show an altered Tnc expression pattern. Here, we investigated the expression of Tnc isoforms in neural stem/progenitor cells and their regulation by the paired-box transcription factor Pax6. Neural stem/progenitor cells cultured as neurospheres strongly expressed Tnc on the protein level. The Tnc isoform expression in neural stem/progenitor cells was analyzed by reverse transcriptase-PCR and dot blot Southern hybridization. In total, 20 different Tnc isoforms were detected in neurospheres derived from embryonic fore-brain cell suspensions. The Tnc isoform containing the fibronectin type III domains A1A4BD is novel and might be neural stem/progenitor cell-specific. Transient overexpression of Pax6 in neurospheres of the medial ganglionic eminence did not alter the total Tnc mRNA expression level but showed a pronounced regulative effect on different Tnc isoforms. The larger Tnc isoforms containing four, five, and six additional alternatively spliced fibronectin type III domains were up-regulated, whereas the small Tnc isoforms without any or with one additional domain were down-regulated. Thus, Pax6 is a homeodomain protein that also modulates the splicing machinery. We conclude that the combinatorial code of Tnc isoform expression in the neural stem/progenitor cell is complex and regulated by Pax6. These findings suggest a functional significance for individual Tnc isoforms in neural stem/progenitor cells.
von Holst
Alexander
A
Department of Cell Morphology and Molecular Neurobiology, Ruhr-University Bochum, D-44780 Bochum, Germany. Alexander.vonHolst@ruhr-uni-bochum.de
Egbers
Ursula
U
Prochiantz
Alain
A
Faissner
Andreas
A
D017398:Alternative Splicing; D000818:Animals; D002460:Cell Line; D005136:Eye Proteins / Q000378:metabolism / Q000502:physiology*; D005347:Fibroblasts / Q000378:metabolism; D005353:Fibronectins / Q000737:chemistry; D018507:Gene Expression Regulation, Developmental; D018398:Homeodomain Proteins / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D009474:Neurons / Q000166:cytology* / Q000378:metabolism; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors / Q000378:metabolism / Q000502:physiology*; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000378:metabolism / Q000502:physiology*; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D019063:Tenascin / Q000737:chemistry*; D015854:Up-Regulation
D005136:Eye Proteins; D005353:Fibronectins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; C000605732:Pax6 protein, mouse; D020033:Protein Isoforms; D012097:Repressor Proteins; D019063:Tenascin