👤 Jean-François Beaulieu

Zinc-finger protein 768 (ZNF768) is an emerging transcription factor regulating cell proliferation and senescence. Although the role of ZNF768 in regulating cell fate decision has been demonstrated in vitro, its importance in controlling physiological and pathophysiological processes in vivo is still unclear. Here, we report the generation of a transgenic mouse model allowing the conditional overexpression of ZNF768. This was achieved by inserting an inverted Znf768 coding sequence surrounded by heterologous Cre recognition sites in the Gt(ROSA)26Sor mouse locus (FLExZnf768). To study the impact linked to systemic overexpression of ZNF768, mice carrying the FLExZnf768 allele were crossed with CMV-Cre mice to produce a whole-body ZNF768 transgenic mouse (WB-ZNF768-Tg). As expected, WB-ZNF768-Tg mice showed higher ZNF768 levels in various tissues. These mice were born at the expected Mendelian ratio and did not display apparent phenotypes. Because ZNF768 levels are often overexpressed in cancer, we assessed tumor development in WB-ZNF768-Tg mice. However, ZNF768 overexpression was not sufficient to promote 3-methylcholantrene-induced fibrosarcoma and KRAS Show less

Cell proliferation is a fundamental process required for organismal development, growth, and maintenance. Failure to control this process leads to several diseases, including cancer. Zinc finger protein 768 (ZNF768) is an emerging transcription factor that plays key roles in driving proliferation. In addition to controlling a gene network supporting cell division, ZNF768 physically interacts and inhibits the activity of the tumor suppressor p53. Although the importance of ZNF768 in promoting cell proliferation has been well demonstrated in vitro, the physiological and pathological roles of ZNF768 in vivo are still unknown. Here, we report the generation and characterization of a ZNF768 null mouse model. ZNF768 null mice are viable but show a growth defect early in life. Mouse embryonic fibroblasts (MEFs) isolated from ZNF768 null embryos exhibit higher p53 levels, premature senescence, and higher sensitivity to genotoxic stress. In line with these findings, ZNF768 null mice showed increased radiosensitivity. This effect was associated not only with higher expression of a subset of p53 target genes, but also with alterations in genes regulating transmembrane receptor signaling, cell adhesion, and growth. Because ZNF768 levels are elevated in tumors, we tested the impact of ZNF768 loss on cancer development in mice. Here, we show that ZNF768 deletion was sufficient to repress lung tumor development in a KRAS Show less

Maternal spiral arteries and newly formed decidual capillaries support embryonic development prior to placentation. Previous studies demonstrated that Notch signaling is active in endothelial cells of both decidual capillaries and spiral arteries, however the role of Notch signaling in physiologic decidual angiogenesis and maintenance of the decidual vasculature in early mouse pregnancy has not yet been fully elucidated. We used the Show less

A novel autosomal recessive disorder characterized by pre- and postnatal growth restriction with microcephaly, distinctive craniofacial features, congenital alopecia, hypoplastic kidneys with renal insufficiency, global developmental delay, severe congenital sensorineural hearing loss, early mortality, hydrocephalus, and genital hypoplasia was observed in 4 children from 3 families of New Mexican Hispanic heritage. Three of the children died before 3 years of age from uremia and/or sepsis. Exome sequencing of the surviving individual identified a homozygous c.587T>C (p.Ile196Thr) mutation in ZPR1 Zinc Finger (ZPR1) that segregated appropriately in her family. In a second family, the identical variant was shown to be heterozygous in the affected individual's parents and not homozygous in any of her unaffected siblings. ZPR1 is a ubiquitously expressed, highly conserved protein postulated to transmit proliferative signals from the cell membrane to the nucleus. Structural modeling reveals that p.Ile196Thr disrupts the hydrophobic core of ZPR1. Patient fibroblast cells showed no detectable levels of ZPR1 and the cells showed a defect in cell cycle progression where a significant number of cells remained arrested in the G1 phase. We provide genetic and molecular evidence that a homozygous missense mutation in ZPR1 is associated with a rare and recognizable multisystem syndrome. Show less

Hepatocyte nuclear factor 4α (HNF4α) is a nuclear transcription factor mainly expressed in the liver, intestine, kidney, and pancreas. Many of its hepatic and pancreatic functions have been described, but limited information is available on its role in the gastrointestinal tract. The objectives of this study were to evaluate the anti-inflammatory and antioxidant functions of HNF4α as well as its implication in intestinal lipid transport and metabolism. To this end, the HNF4A gene was knocked down by transfecting Caco-2 cells with a pGFP-V-RS lentiviral vector containing an shRNA against HNF4α. Inactivation of HNF4α in Caco-2 cells resulted in the following: (a) an increase in oxidative stress as demonstrated by the levels of malondialdehyde and conjugated dienes; (b) a reduction in secondary endogenous antioxidants (catalase, glutathione peroxidase, and heme oxygenase-1); (c) a lower protein expression of nuclear factor erythroid 2-related factor that controls the antioxidant response elements-regulated antioxidant enzymes; (d) an accentuation of cellular inflammatory activation as shown by levels of nuclear factor-κB, interleukin-6, interleukin-8, and leukotriene B4; (e) a decrease in the output of high density lipoproteins and of their anti-inflammatory and anti-oxidative components apolipoproteins (apo) A-I and A-IV; (f) a diminution in cellular lipid transport revealed by a lower cellular secretion of chylomicrons and their apoB-48 moiety; and (g) alterations in the transcription factors sterol regulatory element-binding protein 2, peroxisome proliferator-activated receptor α, and liver X receptor α and β. In conclusion, HNF4α appears to play a key role in intestinal lipid metabolism as well as intestinal anti-oxidative and anti-inflammatory defense mechanisms. Show less

The present investigation aimed at defining the localization of apolipoproteins (apo) A-I, A-IV, B-48, and B-100 along the crypt-villus axis of the human fetal colon, their biogenesis during gestation, and their hormonal regulation. Using immunofluorescence, the distribution of apo A-I and A-IV appeared as a gradient, increasing from the developing crypt to the tip of the villus. On the other hand, apo B-100 staining was found in the crypt and the lower mid-villus region with varying intensities in the upper villus cells, while the 2D8 antibody which recognizes both apo B-100 and B-48, revealed uniform staining along the crypt-villus axis. Apolipoprotein synthesis, determined by [35S] methionine labeling, immunoprecipitation, and SDS-PAGE showed a predominance of apo A-IV (53%), followed by apo A-I (23.9%), apo B-48 (13.4%), and apo B-100 (9.7%). The synthesis of each apolipoprotein was significantly modulated by hydrocortisone, insulin and epidermal growth factor (EGF). Apart from a decrease in apo B-100 exerted by EGF and a reduction in apo A-I resulting from the addition of insulin, the other apolipoproteins were all enhanced. Our data confirm that the fetal colon has the capacity to synthesize apolipoprotein A-I, A-IV, B-48, and B-100 and establish that their synthesis are modulated by hormonal and growth factors known to be involved in the regulatory mechanism of the functional development of human jejunum. Show less