Biomedical subjects

Martin F Crook

Publications and source records attributed to Martin F Crook.

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↗

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

Gene transfer strategies to inhibit neointima formation.

Vascular smooth muscle cell (VSMC) proliferation after arterial injury results in neointima formation and plays an important role in the pathogenesis of restenosis after angioplasty, in-stent restenosis, vascular bypass graft occlusion, and allograft vasculopathy. Major progress has been made recently in elucidating the cellular and molecular mechanisms underlying neointima formation. However, no known curative treatment currently exists. In cases in which pharmacologic and surgical interventions have had limited success, gene therapy remains a potential strategy for the treatment of such vascular proliferative diseases. To date, recombinant adenoviral vectors continue to be the most efficient methods of gene transfer into the arterial wall. However, concerns over the safety of using viral vectors in a clinical situation have inspired the considerable progress that has been made in improving both viral and nonviral modes of gene transfer. This review discusses some of the recent insights and outstanding progress in vascular gene therapeutic approaches to inhibit neointima both from a biologic and therapeutic perspective.

Animals↗

PubMed2002

A growth factor-dependent nuclear kinase phosphorylates p27(Kip1) and regulates cell cycle progression.

The cyclin-dependent kinase inhibitor, p27(Kip1), which regulates cell cycle progression, is controlled by its subcellular localization and subsequent degradation. p27(Kip1) is phosphorylated on serine 10 (S10) and threonine 187 (T187). Although the role of T187 and its phosphorylation by Cdks is well-known, the kinase that phosphorylates S10 and its effect on cell proliferation has not been defined. Here, we identify the kinase responsible for S10 phosphorylation as human kinase interacting stathmin (hKIS) and show that it regulates cell cycle progression. hKIS is a nuclear protein that binds the C-terminal domain of p27(Kip1) and phosphorylates it on S10 in vitro and in vivo, promoting its nuclear export to the cytoplasm. hKIS is activated by mitogens during G(0)/G(1), and expression of hKIS overcomes growth arrest induced by p27(Kip1). Depletion of KIS using small interfering RNA (siRNA) inhibits S10 phosphorylation and enhances growth arrest. p27(-/-) cells treated with KIS siRNA grow and progress to S/G(2 )similar to control treated cells, implicating p27(Kip1) as the critical target for KIS. Through phosphorylation of p27(Kip1) on S10, hKIS regulates cell cycle progression in response to mitogens.

3T3 Cells↗

PubMed2002

Role of nuclear factor-kappa B activation in metalloproteinase-1, -3, and -9 secretion by human macrophages in vitro and rabbit foam cells produced in vivo.

Metalloproteinase secretion by macrophages is believed to play a key role in the matrix degradation that underlies atherosclerotic plaque instability and aneurysm formation. We studied the hypothesis that nuclear factor-kappaB (NF-kappaB), a transcription factor, is necessary for metalloproteinase secretion and, hence, is a target for pharmacological intervention. Adenovirus-mediated gene transfer of the inhibitory NF-kappaB subunit, I-kappa Balpha, was achieved into human monocyte-derived macrophages in vitro and into foam cells produced in vivo in cholesterol-fed rabbits. Human macrophages and rabbit foam cells secreted matrix-degrading metalloproteinase (MMP)-9 without further stimulation, and this was not inhibited by I-kappaBalpha (11+/-16% and 8+/-10%, respectively; P> 0.05). MMP-1 secretion from human macrophages increased in response to recombinant human CD40 ligand and was inhibited 92+/-5% by I-kappaBalpha (n=3, P<0.05). Rabbit foam cells secreted MMP-1 and -3 without further stimulation, and this was inhibited 83+/-12% and 69+/-11%, respectively, by I-kappaBalpha (n=6 or 7, P<0.001). I-kappaBalpha did not significantly affect the expression or activity of tissue inhibitor of metalloproteinases-1 or -2. Overexpression of I-kappaBalpha inhibited collagenolytic and beta-caseinolytic activity by 42+/-2% and 41+/-7%, respectively (n=3, P<0.05). Secretion of MMP-1 and MMP-3 from macrophages stimulated in vitro or in vivo depends on the activation of NF-kappaB. Because the inhibition of NF-kappaB reduces proteolytic activity, it appears to be an attractive pharmacological target in unstable atheromas.

Adenoviridae↗

PubMedDate not supplied

Both ICAM-1- and VCAM-1-integrin interactions are important in mediating monocyte adhesion to human saphenous vein.

Atherosclerosis underlies late occlusion of human saphenous vein (HSV) coronary artery bypass grafts. Monocyte infiltration is implicated, but its mechanisms are unclear given that HSV normally expresses the ICAM-1 but not the VCAM-1 adhesion molecule. To define the mechanisms underlying monocyte adhesion, samples of HSV taken from coronary artery bypass graft patients were co-cultured with human monocytes and adherent monocytes were quantified by immunocytochemistry for CD68 on transverse sections. Pre-treatment of veins with anti-ICAM-1 antibodies reduced monocyte adhesion (monocytes/mm of section) from 7.2 +/- 1.5 to 3.1 +/- 0.7 (p < 0.05, n = 6), but the effect of anti-VCAM-1 was not significant (4.1 +/- 0.7). Paradoxically, pre-treatment of monocytes with either anti-beta(2)-integrins, the counter-receptor of ICAM-1, or anti-alpha(4) integrins, the counter-receptor of VCAM-1, significantly reduced adhesion (1.8 +/- 0.6 and 2.4 +/- 0.7, respectively, p < 0.05). These results were clarified by immunocytochemistry, which confirmed that VCAM-1 expression was absent in harvested vein but was induced in the endothelium during co-culture. Consistent with this, when anti-ICAM-1 or anti-VCAM-1 was present throughout co-culture, either of them reduced adhesion (from 4.2 +/- 0.9 to 2.3 +/- 0.5 and 2.2 +/- 0.4, respectively, p < 0.02, n = 8) and there was no further effect of adding both (2.0 +/- 0.5). These results demonstrate that both ICAM-1/beta(2) and VCAM-1/alpha(4) integrin interactions mediate monocyte adhesion to HSV, possibly as part of a common pathway. These experiments imply that either integrin might be targeted to reduce monocyte infiltration into HSV grafts.

Antigens, CD↗