Overexpression of Zinc‐Finger Protein 777 (ZNF777) Inhibits Proliferation at Low Cell Density Through Down‐Regulation of FAM129A

Abstract

Krüppel-associated box-containing zinc finger proteins (KRAB-ZFPs) regulate a wide range of cellular processes. KRAB-ZFPs have a KRAB domain, which binds to transcriptional corepressors, and a zinc finger domain, which binds to DNA to activate or repress gene transcription. Here, we characterize ZNF777, a member of KRAB-ZFPs. We show that ZNF777 localizes to the nucleus and inducible overexpression of ZNF777 inhibits cell proliferation in a manner dependent on its zinc finger domain but independent of its KRAB domain. Intriguingly, ZNF777 overexpression drastically inhibits cell proliferation at low cell density but slightly inhibits cell proliferation at high cell density. Furthermore, ZNF777 overexpression decreases the mRNA level of FAM129A irrespective of cell density. Importantly, the protein level of FAM129A strongly decreases at low cell density, but at high cell density the protein level of FAM129A does not decrease to that observed at low cell density. ZNF777-mediated inhibition of cell proliferation is attenuated by overexpression of FAM129A at low cell density. Furthermore, ZNF777-mediated down-regulation of FAM129A induces moderate levels of the cyclin-dependent kinase inhibitor p21. These results suggest that ZNF777 overexpression inhibits cell proliferation at low cell density and that p21 induction by ZNF777-mediated down-regulation of FAM129A plays a role in inhibition of cell proliferation.

The possible roles of B‐cell novel protein‐1 (BCNP1) in cellular signalling pathways and in cancer

“…A recent study by Yuki et al . showed that overexpression of a zinc‐finger protein (ZNF777) inhibited proliferation of cells at low density through down‐regulation of FAM129A (Niban) 18. This finding and our finding that there is striking up‐regulated expression of BCNP1 on stimulation of LD ALL3 cells by HDSN of HD ALL3 cells strongly suggests that BCNP1 might have an important role in cell density‐dependent cell proliferation at least in B‐cells.…”

“…Given the relative frequency of BCNP1 alterations in many cancer types warrant further investigation of its function providing answers to question when BCNP1 is amplified, deleted or mutated. Our recent observation that BCNP1 (FAM129C) was the most highly up-regulated gene when non-growing low density Ph+ ALL3 cells were stimulated to proliferate by cell-free supernate from the same cells growing rapidly at a high cell density, and Yuki's report that overexpression of ZNF777 inhibited proliferation of cells at low density by down-regulating FAM129A, suggests that BCNP1 probably has a very important role in cell-cell communication and corresponding intracellular signalling pathways [16,17,18].…”

“…In our microarray study, we found that BCNP1 was the most highly up-regulated gene (~27, 49, and 121-fold, respectively, on days 1, 3 and 6) upon stimulation of the LD ALL3 cells by diffusible factors in HD ALL3 HDSN [16,17]. A recent study by Yuki et al showed that overexpression of a zinc-finger protein (ZNF777) inhibited proliferation of cells at low density through down-regulation of FAM129A (Niban) [18]. This finding and our finding that there is striking up-regulated expression of BCNP1 on stimulation of LD ALL3 cells by HDSN of HD ALL3 cells strongly suggests that BCNP1 might have an important role in cell density-dependent cell proliferation at least in B-cells.…”

Src Acts as an Effector for Ku70-dependent Suppression of Apoptosis through Phosphorylation of Ku70 at Tyr-530

“…4, A and B), both myc-Ku70 and myc-Ku70/sh R constructs were acceptable for transfection into HeLa S3/shKu70 cells. pEBmulti/puro/myc-Ku70-WT or its mutant was constructed as follows: the XhoI and NotI sites were created at the both ends of pcDNA3/myc-Ku70 by PCR with 5Ј-GTCACTCGAGATGGAGCAGAAACTCATCTCT-GAAGAGG-3Ј (sense) and 5Ј-TCATGCGGCCGCTCAGTC-CTGGAAGTGCTTGG-3Ј (antisense), and the XhoI-NotI fragment of the PCR product was subcloned into the episomal pEBmulti/puro vector (Wako Pure Chemical Industries) (73). Intact c-Src and HA-tagged c-Src (c-Src-HA) were constructed from cDNA encoding human wild-type Src (Ref.…”

Role for Tyrosine Phosphorylation of A-kinase Anchoring Protein 8 (AKAP8) in Its Dissociation from Chromatin and the Nuclear Matrix

“…The EBNA1-based episomal pEBMulti-H1 vector, which encodes the H1 promoter and a neomycin-resistant gene, was generated from the pEBMulti vector (Wako Pure Chemical Industries, Osaka, Japan) by replacing the CAG promoter with the H1 promoter as described (37). The oligonucleotides used for shRNA were annealed and subcloned into the pEBMulti-H1 vector (37)(38)(39). To generate AKAP8-knockdown cells, HCT116 cells were transfected with pEBMulti-neo/shAKAP8 selected in 600 g/ml G418.…”