title: Inability to enter S phase and defective RNA polymerase II CTD phosphorylation in mice lacking Mat1.
abstract: The trimeric Cdk7-cyclin H-Mat1 complex comprises the kinase subunit of basal transcription factor TFIIH and has been shown to function as a cyclin-dependent kinase (Cdk)-activating kinase. Herein we report that disruption of the murine Mat1 gene leads to peri-implantation lethality coincident with depletion of maternal Mat1 protein. In culture, Mat1(-/-) blastocysts gave rise to viable post-mitotic trophoblast giant cells while mitotic lineages failed to proliferate and survive. In contrast to wild-type trophoblast giant cells, Mat1(-/-) cells exhibited a rapid arrest in endoreduplication, which was characterized by an inability to enter S phase. Additionally, Mat1(-/-) cells exhibited defects in phosphorylation of the C-terminal domain (CTD) of RNA polymerase II on both Ser5 and Ser2 of the heptapeptide repeat. Despite this, Mat1(-/-) cells demonstrated apparent transcriptional and translational integrity. These data indicate an essential role for Mat1 in progression through the endocycle and suggest that while Mat1 modulates CTD phosphorylation, it does not appear to be essential for RNA polymerase II-mediated transcription.
authors.affiliation: Molecular Cancer Biology Research Program, Biomedicum Helsinki and Haartman Institute, University of Helsinki, PO Box 63, 00014 Helsinki, Finland.
authors.forename: D J
authors.initials: DJ
authors.lastname: Rossi
authors.forename: A
authors.initials: A
authors.lastname: Londesborough
authors.forename: N
authors.initials: N
authors.lastname: Korsisaari
authors.forename: A
authors.initials: A
authors.lastname: Pihlak
authors.forename: E
authors.initials: E
authors.lastname: Lehtonen
authors.forename: M
authors.initials: M
authors.lastname: Henkemeyer
authors.forename: T P
authors.initials: TP
authors.lastname: Mäkelä
mesh_terms: D000818:Animals; D001665:Binding Sites; D001755:Blastocyst / Q000166:cytology* / Q000502:physiology; D002453:Cell Cycle / Q000502:physiology*; D018844:Cyclin-Dependent Kinases; D005260:Female; D005313:Fetal Death; D005838:Genotype; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D010766:Phosphorylation; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D014176:Protein Biosynthesis; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism*; D012319:RNA Polymerase II / Q000378:metabolism*; D020449:Repetitive Sequences, Amino Acid; D016196:S Phase; D012694:Serine; D051758:Transcription Factor TFIIH; D014157:Transcription Factors / Q000378:metabolism; D019473:Transcription Factors, TFII; D014158:Transcription, Genetic; D014327:Trophoblasts / Q000166:cytology; D000095043:Cyclin-Dependent Kinase-Activating Kinase
chemical_list: D018844:Cyclin-Dependent Kinases; D017346:Protein Serine-Threonine Kinases; D012319:RNA Polymerase II; D012694:Serine; D051758:Transcription Factor TFIIH; D014157:Transcription Factors; D019473:Transcription Factors, TFII; D000095043:Cyclin-Dependent Kinase-Activating Kinase; C090586:Cdk7 protein, mouse