BACKGROUND p16(INK4a) tumor suppressor protein has been widely proposed to mediate entrance of the cells into the senescent stage. Promoter of p16(INK4a) gene contains at least five putative GC boxes, named GC-I to V, respectively. Our previous data showed that a potential Sp1 binding site, within the promoter region from -466 to -451, acts as a positive transcription regulatory element. These ...

The transcription factor Sp1 is ubiquitously expressed in different cells and thereby regulates the expression of genes involved in many cellular processes. This study reveals that Sp1 was phosphorylated during the mitotic stage in three epithelial tumor cell lines and one glioma cell line. By using different kinase inhibitors, we found that during mitosis in HeLa cells, the c-Jun NH(2)-termina...

The human neurofilament (H) promoter contains multiple binding sites for nuclear proteins including a Proximal (Prox) site centered around the sequence GGTTGGACC and an adjacent pyrimidine (Pyr) tract site centered around the sequence CCCTCCTCCCC. Surprisingly binding to a probe containing the Prox/Pyr region of the NF(H) promoter was competed in gel shifts by an oligonucleotide containing only...

Mammalian development is regulated by the interplayof tissue-specific and ubiquitously expressed transcription factors, such as Sp1. Sp1 knockout mice die in uterowithmultiple phenotypic aberrations, but the underlyingmolecular mechanism of this differentiation failure has been elusive. Here, we have used conditional knockout mice as well as the differentiation of mouse ES cells as a model with...

PURPOSE The transcription factor specificity protein 1 (Sp1) controls number of cellular processes by regulating the expression of critical cell cycle, differentiation, and apoptosis-related genes containing proximal GC/GT-rich promoter elements. We here provide experimental and clinical evidence that Sp1 plays an important regulatory role in multiple myeloma (MM) cell growth and survival. EX...

The transcription factor Sp1 is implicated in the activation of G0/G1 phase genes. Modulation of Sp1 transcription activities may affect G1-S checkpoint, resulting in changes in cell proliferation. In this study, our results demonstrated that activated poly(ADP-ribose) polymerase 1 (PARP-1) promoted cell proliferation by inhibiting Sp1 signaling pathway. Cell proliferation and cell cycle assays...

Copper is an essential micronutrient for cell growth but is toxic in excess. Copper transporter (Ctr1) plays an important role in regulating adequate copper levels in mammalian cells. We have shown previously that expression of the human high-affinity copper transporter (hCtr1) was transcriptionally up-regulated under copper-depleted conditions and down-regulated under replete conditions; moreo...

Cardiac hypertrophy in response to multiple stimuli has important physiological and pathological significances. GATA4 serves as a nuclear integrator of several signalling pathways during cardiac hypertrophy. Sp1 and Sp3 are also reported to be involved in this process. However, the mechanism by which GATA4 acts as a mediator, integrating these ubiquitously expressed transcriptional factors, is ...

Gene activation by NF-kappaB/Rel transcription factors is modulated by synergistic or antagonistic interactions with other promoter-bound transcription factors. For example, Sp1 sites are often found in NF-kappaB-regulated genes, and Sp1 can activate certain promoters in synergism with NF-kappaB through nonoverlapping binding sites. Here we report that Sp1 acts directly through a subset of NF-k...

We have followed Sp1 expression in primary human T lymphocytes induced, via CD2 plus CD28 costimulation, to sustained proliferation and subsequent return to quiescence. Binding of Sp1 to wheat germ agglutinin lectin was not modified following activation, indicating that the overall glycosylation of the protein was unchanged. Sp1 underwent, instead, a major dephosphorylation that correlated with...