The bHLH gene hes1 as a repressor of the neuronal commitment of CNS stem cells.
Hes1 is one of the basic helix-loop-helix transcription factors that regulate mammalian CNS development, and its loss- and gain-of-function phenotypes indicate that it negatively regulates neuronal differentiation. Here we report that Hes1(-/-) mice expressed both early (TuJ1 and Hu) and late (MAP2 and Neurofilament) neuronal markers prematurely, and that there were approximately twice the normal number of neurons in the Hes1(-/-) brain during early neural development. However, immunochemical analyses of sections and dissociated cells using neural progenitor markers, including nestin, failed to detect any changes in Hes1(-/-) progenitor population. Therefore, further characterization of neural progenitor cells that discriminated between multipotent and monopotent cells was performed using two culture methods, low-density culture, and a neurosphere assay. We demonstrate that the self-renewal activity of multipotent progenitor cells was reduced in the Hes1(-/-) brain, and that their subsequent commitment to the neuronal lineage was accelerated. The Hes1(-/-) neuronal progenitor cells were functionally abnormal, in that they divided, on average, only once, and then generated two neurons, (instead of one progenitor cell and one neuron), whereas wild-type progenitor cells divided more. In addition, some Hes1(-/-) progenitors followed an apoptotic fate. The overproduction of neurons in the early Hes1(-/-) brains may reflect this premature and immediate generation of neurons as well as a net increase in the number of neuronal progenitor cells. Taken together, we conclude that Hes1 is important for maintaining the self-renewing ability of progenitors and for repressing the commitment of multipotent progenitor cells to a neuronal fate, which is critical for the correct number of neurons to be produced and for the establishment of normal neuronal function.
Nakamura
Y
Y
Department of Neuroanatomy, Biomedical Research Center, Osaka University, Suita, Osaka 565-0871, Japan.
Sakakibara
S i
Si
Miyata
T
T
Ogawa
M
M
Shimazaki
T
T
Weiss
S
S
Kageyama
R
R
Okano
H
H
D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002449:Cell Aggregation; D002454:Cell Differentiation / Q000502:physiology; D019070:Cell Lineage / Q000502:physiology; D002478:Cells, Cultured; D005260:Female; D005656:Fungal Proteins / Q000235:genetics*; D018257:Helix-Loop-Helix Motifs / Q000502:physiology*; D020287:In Situ Nick-End Labeling; D007381:Intermediate Filament Proteins / Q000032:analysis; D051379:Mice; D018345:Mice, Knockout; D008869:Microtubule-Associated Proteins / Q000032:analysis; D009419:Nerve Tissue Proteins; D064231:Nestin; D016900:Neurofilament Proteins / Q000032:analysis; D009474:Neurons / Q000737:chemistry / Q000166:cytology*; D011247:Pregnancy; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis; D029701:Saccharomyces cerevisiae Proteins; D013234:Stem Cells / Q000737:chemistry / Q000166:cytology*; D014158:Transcription, Genetic / Q000502:physiology; D000098825:Oxysterol Binding Proteins
D005656:Fungal Proteins; D007381:Intermediate Filament Proteins; D008869:Microtubule-Associated Proteins; D009419:Nerve Tissue Proteins; D064231:Nestin; D016900:Neurofilament Proteins; D018809:Proliferating Cell Nuclear Antigen; D029701:Saccharomyces cerevisiae Proteins; C087902:HES1 protein, S cerevisiae; D000098825:Oxysterol Binding Proteins; C577485:Nes protein, mouse; C061195:neurofilament protein M