The neuronal microtubule-associated protein 1B is under homeoprotein transcriptional control.
To identify genes regulated by homeoprotein transcription factors in postnatal neurons, the DNA-binding domain (homeodomain) of Engrailed homeoprotein was internalized into rat cerebellum neurons. The internalized homeodomain (EnHD) acts as a competitive inhibitor of Engrailed and of several homeoproteins (Mainguy et al., 2000). Analysis by differential display revealed that microtubule-associated protein 1B (MAP1B) mRNA is upregulated by EnHD. This upregulation does not require protein synthesis, suggesting a direct effect of the homeodomain on MAP1B transcription. The promoter region of MAP1B was cut into several subdomains, and each subdomain was tested for its ability to bind Engrailed and EnHD and to associate with Engrailed-containing cerebellum nuclear extracts. In addition, the activity, and regulation by Engrailed, of each subdomain and of the entire promoter were evaluated in vivo by electroporation in the chick embryo neural tube. These experiments demonstrate that MAP1B promoter is regulated by Engrailed in vivo. Moreover, they show that one promoter domain that contains all ATTA homeoprotein cognate binding sites common to the rat and human genes is an essential element of this regulation. It is thus proposed that MAP1B, a cytoskeleton protein involved in neuronal growth and regeneration, is under homeoprotein transcriptional regulation.
Montesinos
M L
ML
Centre Nationale de la Recherche Scientifique Unité Mixte de Recherche 8542, Ecole Normale Supérieure, 75230 Paris, Cedex 05 France.
Foucher
I
I
Conradt
M
M
Mainguy
G
G
Robel
L
L
Prochiantz
A
A
Volovitch
M
M
D000818:Animals; D001665:Binding Sites / Q000502:physiology; D002478:Cells, Cultured; D002490:Central Nervous System / Q000196:embryology / Q000378:metabolism; D002531:Cerebellum / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D002642:Chick Embryo; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D017930:Genes, Reporter; D018398:Homeodomain Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D011401:Promoter Regions, Genetic / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D014157:Transcription Factors / Q000378:metabolism*; D015854:Up-Regulation
D018398:Homeodomain Proteins; D008869:Microtubule-Associated Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; C106185:engrailed homeobox proteins; C085284:microtubule-associated protein 1B