Mechanisms of MARCKS gene activation during Xenopus development.
The myristoylated alanine-rich protein kinase C substrate (MARCKS) is a high affinity cellular substrate for protein kinase C. The MARCKS gene is under multiple modes of transcriptional control, including cytokine- and transformation-dependent, cell-specific, and developmental regulation. This study evaluated the transcriptional control of MARCKS gene expression during early development of Xenopus laevis. Xenopus MARCKS was highly conserved with its mammalian and avian homologues; its mRNA and protein were abundant in the maternal pool and increased after the mid-blastula transition (MBT). The Xenopus MARCKS gene was similar to those of other species, except that a second intron interrupted the 5'- untranslated region. By transiently transfecting XTC-2 cells and microinjecting Xenopus embryos with reporter gene constructs containing serial deletions of 5'-flanking MARCKS sequences, we identified a 124-base pair minimal promoter that was critical for promoter activity. Developmental gel shift assays revealed that a CBF/NF-Y/CP-1-like factor and an Sp1-like factor bound to this region in a manner correlating with the onset of Xenopus MARCKS transcription at MBT. Mutations in the promoter that abolished binding of these two factors also completely inhibited transcriptional activation of the MARCKS gene at MBT. The binding sites for these two factors are highly conserved in the human and mouse MARCKS promoters, suggesting that these elements might also regulate MARCKS transcription in other species. These studies not only increase our knowledge of the transcriptional regulation of the MARCKS genes but also have implications for the mechanisms responsible for zygotic activation of the Xenopus genome at MBT.
Shi
Y
Y
Howard Hughes Medical Institute and the Section of Diabetes and Metabolism, Division of Endocrinology, Metabolism and Nutrition, Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA.
Sullivan
S K
SK
Pitterle
D M
DM
Kennington
E A
EA
Graff
J M
JM
Blackshear
P J
PJ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; D051379:Mice; D008969:Molecular Sequence Data; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D011401:Promoter Regions, Genetic; D011506:Proteins / Q000235:genetics*; D012045:Regulatory Sequences, Nucleic Acid; D017386:Sequence Homology, Amino Acid; D016329:Sp1 Transcription Factor / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D015533:Transcriptional Activation; D014982:Xenopus laevis / Q000196:embryology
D018076:DNA, Complementary; D047908:Intracellular Signaling Peptides and Proteins; C000619710:MARCKS protein, human; C000619711:Marcks protein, mouse; D008565:Membrane Proteins; D011506:Proteins; D016329:Sp1 Transcription Factor; D014157:Transcription Factors; D000076250:Myristoylated Alanine-Rich C Kinase Substrate