Lot1, a zinc finger transcription factor acting as a tumor suppressor gene on tumoral cells, is highly expressed during brain development. In developing rat cerebellum, Lot1 expression is high in cerebellar granule cells (CGC), a neuronal population undergoing postnatal neurogenesis. The time course of Lot1 cerebellar expression closely matches the expression of pituitary adenylate cyclase-activating polypeptide (PACAP) receptors coupled to adenylyl cyclase. The aim of this study was to ascertain whether Lot1 expression is regulated by cAMP-dependent pathways and to identify mechanisms of Lot1 activation in CGC cultures. Our results show that Lot1 expression in CGC is cAMP-dependent, as treatments with either forskolin or PACAP-38 induced an increase in its expression at both the mRNA and protein levels. This effect on Lot1 expression was mimicked by dibutyryl cAMP and suppressed by protein kinase A and MEK inhibitors. In parallel, we found that treatments with forskolin and PACAP-38 in precursor CGC inhibited bromodeoxyuridine incorporation by 25 and 35%, respectively, indicating a negative effect on neuronal precursor proliferation. Luciferase reporter analysis and mutagenesis of the Lot1 promoter region indicated a crucial role of the AP1-binding site (located at -268 bp) in cAMP-induced Lot1 transcription. In addition, cotransfection experiments indicated that the c-Fos/c-Jun heterodimer is responsible for cAMP-dependent Lot1 transcriptional activation. In conclusion, our data demonstrate that, in CGC, Lot1 is under the transcriptional control of cAMP through an AP1 site regulated by the c-Fos/c-Jun heterodimer and suggest that this gene may be an important element of the cAMP-mediated pathway that regulates neuronal proliferation through the protein kinase A-MEK signaling cascade.

CONTESTABILE A., FILA T., BARTESAGHI R., CIANI E. (2005). Cyclic AMP-mediated regulation of transcription factor Lot1 expression in cerebellar granule cells. THE JOURNAL OF BIOLOGICAL CHEMISTRY, 280, 33541-33551.

Cyclic AMP-mediated regulation of transcription factor Lot1 expression in cerebellar granule cells.

CONTESTABILE, ANDREA;FILA, TATIANA;BARTESAGHI, RENATA;CIANI, ELISABETTA
2005

Abstract

Lot1, a zinc finger transcription factor acting as a tumor suppressor gene on tumoral cells, is highly expressed during brain development. In developing rat cerebellum, Lot1 expression is high in cerebellar granule cells (CGC), a neuronal population undergoing postnatal neurogenesis. The time course of Lot1 cerebellar expression closely matches the expression of pituitary adenylate cyclase-activating polypeptide (PACAP) receptors coupled to adenylyl cyclase. The aim of this study was to ascertain whether Lot1 expression is regulated by cAMP-dependent pathways and to identify mechanisms of Lot1 activation in CGC cultures. Our results show that Lot1 expression in CGC is cAMP-dependent, as treatments with either forskolin or PACAP-38 induced an increase in its expression at both the mRNA and protein levels. This effect on Lot1 expression was mimicked by dibutyryl cAMP and suppressed by protein kinase A and MEK inhibitors. In parallel, we found that treatments with forskolin and PACAP-38 in precursor CGC inhibited bromodeoxyuridine incorporation by 25 and 35%, respectively, indicating a negative effect on neuronal precursor proliferation. Luciferase reporter analysis and mutagenesis of the Lot1 promoter region indicated a crucial role of the AP1-binding site (located at -268 bp) in cAMP-induced Lot1 transcription. In addition, cotransfection experiments indicated that the c-Fos/c-Jun heterodimer is responsible for cAMP-dependent Lot1 transcriptional activation. In conclusion, our data demonstrate that, in CGC, Lot1 is under the transcriptional control of cAMP through an AP1 site regulated by the c-Fos/c-Jun heterodimer and suggest that this gene may be an important element of the cAMP-mediated pathway that regulates neuronal proliferation through the protein kinase A-MEK signaling cascade.
2005
CONTESTABILE A., FILA T., BARTESAGHI R., CIANI E. (2005). Cyclic AMP-mediated regulation of transcription factor Lot1 expression in cerebellar granule cells. THE JOURNAL OF BIOLOGICAL CHEMISTRY, 280, 33541-33551.
CONTESTABILE A.; FILA T.; BARTESAGHI R.; CIANI E.
File in questo prodotto:
Eventuali allegati, non sono esposti

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/13475
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 14
  • ???jsp.display-item.citation.isi??? 12
social impact