Biomedical subjects

Michelle Olive

Publications and source records attributed to Michelle Olive.

6 recordsLinked to original sources

PubMed2006

The arginine methyltransferase PRMT2 binds RB and regulates E2F function.

The retinoblastoma gene product (RB) is an important regulator of E2F activity. RB recruits a number of proteins, including HDACs, SWI/SNF complex, lysine methyl transferase (SUV39H1) and DNA methyltransferase (DNMT1), all of which negatively regulate E2F activity with RB. Here, we show that RB interacts with PRMT2, a member of the protein arginine methyltransferase family, to regulate E2F activity. PRMT2 directly bound and interacted with RB through its AdoMet binding domain, in contrast to other PRMT proteins, including PRMT1, PRMT3 and PRMT4. In reporter assays, PRMT2 repressed E2F1 transcriptional activity in an RB-dependent manner. PRMT2 formed a ternary complex with E2F1 in the presence of RB. To further explore the role of endogenous PRMT2 in the regulation of E2F activity, the PRMT2 gene was ablated in mice by gene targeting. Compared with PRMT2(+/+) mouse embryonic fibroblasts (MEFs), PRMT2(-/-) MEFs demonstrated increased E2F activity and early S phase entry following release of serum starvation. Vascular injury to PRMT2(-/-) arteries results in a hyperplastic response, consistent with increased G1-S phase progression. Taken together, these findings demonstrate a novel mechanism for the regulation of E2F activity by a member of the protein arginine methyltransferase family.

Animals↗

PubMed2006

Progressive vascular smooth muscle cell defects in a mouse model of Hutchinson-Gilford progeria syndrome.

Children with Hutchinson-Gilford progeria syndrome (HGPS) suffer from dramatic acceleration of some symptoms associated with normal aging, most notably cardiovascular disease that eventually leads to death from myocardial infarction and/or stroke usually in their second decade of life. For the vast majority of cases, a de novo point mutation in the lamin A (LMNA) gene is the cause of HGPS. This missense mutation creates a cryptic splice donor site that produces a mutant lamin A protein, termed "progerin," which carries a 50-aa deletion near its C terminus. We have created a mouse model for progeria by generating transgenics carrying a human bacterial artificial chromosome that harbors the common HGPS mutation. These mice develop progressive loss of vascular smooth muscle cells in the medial layer of large arteries, in a pattern very similar to that seen in children with HGPS. This mouse model should prove valuable for testing experimental therapies for this devastating disorder and for exploring cardiovascular disease in general.

Animals↗

PubMed2005

The cell cycle regulator p27Kip1 interacts with MCM7, a DNA replication licensing factor, to inhibit initiation of DNA replication.

The G1/S phase restriction point is a critical checkpoint that interfaces between the cell cycle regulatory machinery and DNA replicator proteins. Here, we report a novel function for the cyclin-dependent kinase inhibitor p27Kip1 in inhibiting DNA replication through its interaction with MCM7, a DNA replication protein that is essential for initiation of DNA replication and maintenance of genomic integrity. We find that p27Kip1 binds the conserved minichromosome maintenance (MCM) domain of MCM7. The proteins interact endogenously in vivo in a growth factor-dependent manner, such that the carboxyl terminal domain of p27Kip1 inhibits DNA replication independent of its function as a cyclin-dependent kinase inhibitor. This novel function of p27Kip1 may prevent inappropriate initiation of DNA replication prior to S phase.

Binding Sites↗

PubMed2004

Bone marrow-derived immune cells regulate vascular disease through a p27(Kip1)-dependent mechanism.

The cyclin-dependent kinase inhibitors are key regulators of cell cycle progression. Although implicated in carcinogenesis, they inhibit the proliferation of a variety of normal cell types, and their role in diverse human diseases is not fully understood. Here, we report that p27(Kip1) plays a major role in cardiovascular disease through its effects on the proliferation of bone marrow-derived (BM-derived) immune cells that migrate into vascular lesions. Lesion formation after mechanical arterial injury was markedly increased in mice with homozygous deletion of p27(Kip1), characterized by prominent vascular infiltration by immune and inflammatory cells. Vascular occlusion was substantially increased when BM-derived cells from p27(-/-) mice repopulated vascular lesions induced by mechanical injury in p27(+/+) recipients, in contrast to p27(+/+) BM donors. To determine the contribution of immune cells to vascular injury, transplantation was performed with BM derived from RAG(-/-) and RAG(+/+) mice. RAG(+/+) BM markedly exacerbated vascular proliferative lesions compared with what was found in RAG(-/-) donors. Taken together, these findings suggest that vascular repair and regeneration is regulated by the proliferation of BM-derived hematopoietic and nonhematopoietic cells through a p27(Kip1)-dependent mechanism and that immune cells largely mediate these effects.

Animals↗

PubMed2003

Using Xenopus as a model system for an undergraduate laboratory course in vertebrate development at the University of Bordeaux, France.

The goal of this laboratory course is to introduce vertebrate developmental biology to undergraduate students, emphasizing both classical and contemporary aspects of this field. During the course, the students combine the use of living Xenopus laevis material with active tutorial participation, with the aim of illustrating how the fertilized egg can generate the diversity of cell types and complexity of pattern seen only a few days later in the embryo. Special emphasis is given to the observation and manipulation of living material. The laboratory course includes a comprehensive analysis of both oogenesis and early development and is divided into two overlapping parts that combine tutorial and practical approaches. The first part is devoted to oogenesis; oocytes are sorted out, allowed to mature in vitro and observed in histological section. In the second part, students perform an in vitro fertilization of Xenopus eggs and a mesoderm and neural induction assay of animal cap explants. Successful induction of the explants is confirmed by morphological, histological and molecular analyses. Finally, the students observe and comment on selected slides to illustrate the organization of the body plan of the amphibian embryo at an early stage of organogenesis.

Animals↗

PubMed2002

Adenoviral delivery of A-FOS, an AP-1 dominant negative, selectively inhibits drug resistance in two human cancer cell lines.

Activator protein-1 (AP-1) transcription factor has been linked to chemotherapeutic resistance. To assess the clinical efficacy of AP-1 inhibition toward reversing drug resistance, we have developed an adenovirus expressing a dominant negative that inhibits AP-1 DNA binding, namedAdA-FOS. We examined the consequence of AdA-FOS infection on two paired human cancer cell lines, each pair consisting of a parental cell and the drug- resistant derivative. The first pair of cells is the parental human ovarian cancer cell line A2780 and the cisplatin-resistant A2780/CP70 cell line. The second pair of cells is the parental epidermal carcinoma cell line KB8 and the multidrug-resistant (mdr) KB85 cell line. Because of an association of up-regulated AP-1 activity with their drug resistance, these cell lines were considered good targets of AdA-FOS therapy. Following infection of the drug-sensitive and drug-resistant cells, we observed a significant decrease in cell viability of KB85 and A2780/CP70 cells at drug doses normally not lethal to the cell. The parental cell lines, A2780 and KB8 cells, were not similarly affected by AdA-FOS. This decrease in viability was specific to AdA-FOS as an adenovirus control (Advector) did not reverse drug resistance. Although the efficiency of AdA- FOS in therapy would need to be further analyzed with other cisplatin-resistant and mdr cell lines, these results suggest that AP-1 is a therapeutic molecular target and that inhibition of AP-1 DNA binding may be of clinical value in treating chemotherapeutic resistance.

Adenoviridae↗