Ptbp2 represses adult-specific splicing to regulate the generation of neuronal precursors in the embryonic brain.
Two polypyrimidine tract RNA-binding proteins (PTBs), one near-ubiquitously expressed (Ptbp1) and another highly tissue-restricted (Ptbp2), regulate RNA in interrelated but incompletely understood ways. Ptbp1, a splicing regulator, is replaced in the brain and differentiated neuronal cell lines by Ptbp2. To define the roles of Ptbp2 in the nervous system, we generated two independent Ptbp2-null strains, unexpectedly revealing that Ptbp2 is expressed in neuronal progenitors and is essential for postnatal survival. A HITS-CLIP (high-throughput sequencing cross-linking immunoprecipitation)-generated map of reproducible Ptbp2-RNA interactions in the developing mouse neocortex, combined with results from splicing-sensitive microarrays, demonstrated that the major action of Ptbp2 is to inhibit adult-specific alternative exons by binding pyrimidine-rich sequences upstream of and/or within them. These regulated exons are present in mRNAs encoding proteins associated with control of cell fate, proliferation, and the actin cytoskeleton, suggesting a role for Ptbp2 in neurogenesis. Indeed, neuronal progenitors in the Ptbp2-null brain exhibited an aberrant polarity and were associated with regions of premature neurogenesis and reduced progenitor pools. Thus, Ptbp2 inhibition of a discrete set of adult neuronal exons underlies early brain development prior to neuronal differentiation and is essential for postnatal survival.
Laboratory of Molecular Neuro-Oncology, The Rockefeller University, New York, New York 10065, USA.
Donny D
DD
Licatalosi
Masato
M
Yano
John J
JJ
Fak
Aldo
A
Mele
Sarah E
SE
Grabinski
Chaolin
C
Zhang
Robert B
RB
Darnell
D017398:Alternative Splicing / Q000502:physiology*; D000818:Animals; D001921:Brain / Q000196:embryology* / Q000378:metabolism; D002454:Cell Differentiation / Q000502:physiology*; D005091:Exons / Q000502:physiology; D034441:Heterogeneous-Nuclear Ribonucleoproteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008817:Mice, Mutant Strains; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D058953:Neural Stem Cells / Q000166:cytology / Q000378:metabolism*; D038941:Polypyrimidine Tract-Binding Protein / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*
D034441:Heterogeneous-Nuclear Ribonucleoproteins; D009419:Nerve Tissue Proteins; C573992:Ptbp1 protein, mouse; C429773:Ptbp2 protein, mouse; D012333:RNA, Messenger; D038941:Polypyrimidine Tract-Binding Protein