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M Pinard

Publications and source records attributed to M Pinard.

At least 19 recordsLinked to original sources
PubMed2001

A novel regulatory element in the dnmt1 gene that responds to co-activation by Rb and c-Jun.

Rb, c-Jun and dnmt1 play critical roles in the process of cellular differentiation. We demonstrate that a regulatory region of murine dnmt1 contains an element which is responsible for transactivation by Rb and c-Jun in P19 embryocarcinoma cells which is not observed in Y1 adrenocarcinoma cells. During differentiation of P19 cells, the induction of Rb and c-Jun coincides with an increase of dnmt1 mRNA. Using linker scanning mutagenesis we identify the element that is responsible for this activation to be a non-canonical AP-1 site. Our data is an example of how a proto-oncogene activates its downstream effectors by recruiting a tumor suppressor. This interaction of Rb and a proto-oncogene might play an important role in differentiation. The responsiveness of dnmt1 to this type of signal is consistent with an important role for regulated expression of dnmt1 during cellular differentiation.

Animals↗
PubMed1999

DNA methyltransferase is a downstream effector of cellular transformation triggered by simian virus 40 large T antigen.

This paper tests the hypothesis that DNA methyltransferase plays a causal role in cellular transformation induced by SV40 T antigen. We show that T antigen expression results in elevation of DNA methyltransferase (MeTase) mRNA, DNA MeTase protein levels, and global genomic DNA methylation. A T antigen mutant that has lost the ability to bind pRb does not induce DNA MeTase. This up-regulation of DNA MeTase by T antigen occurs mainly at the posttranscriptional level by altering mRNA stability. Inhibition of DNA MeTase by antisense oligonucleotide inhibitors results in inhibition of induction of cellular transformation by T antigen as determined by a transient transfection and soft agar assay. These results suggest that elevation of DNA MeTase is an essential component of the oncogenic program induced by T antigen.

3T3 Cells↗
PubMed1999

Navigating ambulatory referral: a standardized process.

Significant funding and structure changes to healthcare in Ontario in the mid-90's led The Hospital for Sick Children in Toronto to examine patient referral processes. In an effort to streamline access and encourage more appropriate referrals, the hospital tested and implemented three major changes. This article outlines these changes using the PDSA (Plan, Do, Study, Act) improvement framework and summarizes the results from this project.

Ambulatory Care↗
PubMed1999

Feedback regulation of DNA methyltransferase gene expression by methylation.

This paper tests the hypothesis that expression of the DNA methyltransferase, dnmt1, gene is regulated by a methylation-sensitive DNA element. Methylation of DNA is an attractive system for feedback regulation of DNA methyltransferase as the final product of the reaction, methylated DNA, can regulate gene expression in cis. We show that an AP-1-dependent regulatory element of dnmt1 is heavily methylated in most somatic tissues and in the mouse embryonal cell line, P19, and completely unmethylated in a mouse adrenal carcinoma cell line, Y1. dnmt1 is highly over expressed in Y1 relative to P19 cell lines. Global inhibition of DNA methylation in P19 cells by 5-azadeoxycytidine results in demethylation of the AP-1 regulatory region and induction of dnmt1 expression in P19cells, but not Y1 cells. We propose that this regulatory region of dnmt1 acts as a sensor of the DNA methylation capacity of the cell. These results provide an explanation for the documented coexistence of global hypomethylation and high levels of DNA methyltransferase activity in many cancer cells and for the carcinogenic effect of hypomethylating diets.

Animals↗
PubMed1997

Inhibition of tumorigenesis by a cytosine-DNA, methyltransferase, antisense oligodeoxynucleotide.

This paper tests the hypothesis that cytosine DNA methyltransferase (DNA MeTase) is a candidate target for anticancer therapy. Several observations have suggested recently that hyperactivation of DNA MeTase plays a critical role in initiation and progression of cancer and that its up-regulation is a component of the Ras oncogenic signaling pathway. We show that a phosphorothioate-modified, antisense oligodeoxynucleotide directed against the DNA MeTase mRNA reduces the level of DNA MeTase mRNA, inhibits DNA MeTase activity, and inhibits anchorage independent growth of Y1 adrenocortical carcinoma cells ex vivo in a dose-dependent manner. Injection of DNA MeTase antisense oligodeoxynucleotides i.p. inhibits the growth of Y1 tumors in syngeneic LAF1 mice, reduces the level of DNA MeTase, and induces demethylation of the adrenocortical-specific gene C21 and its expression in tumors in vivo. These results support the hypothesis that an increase in DNA MeTase activity is critical for tumorigenesis and is reversible by pharmacological inhibition of DNA MeTase.

Animals↗
PubMed1997

[Diaper rash].

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Diaper Rash↗