Centromere-associated protein-E (CENP-E) is a kinetochore-associated mitotic kinesin that is thought to function as the key receptor responsible for mitotic checkpoint signal transduction after interaction with spindle microtubules. We have identified GSK923295, an allosteric inhibitor of CENP-E kinesin motor ATPase activity, and mapped the inhibitor binding site to a region similar to that bound by loop-5 inhibitors of the kinesin KSP/Eg5. Unlike these KSP inhibitors, which block release of ADP and destabilize motor-microtubule interaction, GSK923295 inhibited release of inorganic phosphate and stabilized CENP-E motor domain interaction with microtubules. Inhibition of CENP-E motor activity in cultured cells and tumor xenografts caused failure of metaphase chromosome alignment and induced mitotic arrest, indicating that tight binding of CENP-E to microtubules is insufficient to satisfy the mitotic checkpoint. Consistent with genetic studies in mice suggesting that decreased CENP-E function can have a tumor-suppressive effect, inhibition of CENP-E induced tumor cell apoptosis and tumor regression.entromere-associated protein-E (CENP-E; kinesin-7) is a kinetochore-associated kinesin motor protein with an essential and exclusive role in metaphase chromosome alignment and satisfaction of the mitotic checkpoint (1). CENP-E is a likely candidate to integrate the mechanics of kinetochore-microtubule interaction with the mitotic checkpoint signaling machinery responsible for restraining cell-cycle progression into anaphase. CENP-E is a large dimeric protein consisting of an N-terminal kinesin motor domain tethered to a globular C-terminal domain through an extended coiled-coil rod domain (2, 3). The C-terminal, noncatalytic region of CENP-E is not only sufficient to specify localization to kinetochores, but it also mediates interaction of CENP-E with the serine/threonine kinase BubR1, a key effector of mitotic checkpoint signaling that forms complexes with the checkpoint proteins Cdc20, Bub3, and Mad2 to inhibit the ubiquitin ligase activity of the anaphase promoting complex APC/C CDC20 (4-7). The combined interaction of CENP-E with microtubules and a key regulator of APC/C CDC20 has led to the hypothesis that CENP-E functions as the key kinetochore microtubule receptor responsible for silencing mitotic checkpoint signal transduction after capture of spindle microtubules. This hypothesis was further strengthened by the finding that CENP-E could stimulate the kinase activity of BubR1 in a microtubule-sensitive manner (8, 9). In vitro, the addition of CENP-E to BubR1 resulted in a stimulation of BubR1 kinase activity. The addition of microtubules suppressed this stimulatory activity, an effect thought to be mediated by the CENP-E kinesin motor domain. Although the importance of CENP-E interaction with BubR1 and the role of BubR1-mediated phosphorylation in mitotic checkpoint function remain unclear, CENP-E remains a prominent candidate to play a key role in mitotic checkpoint signal transduction.Depletion of CENP-E from ...

The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) Project (www.toxpath.org/inhand.asp) is a joint initiative of the Societies of Toxicological Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP) and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying microscopic lesions observed in the female reproductive tract of laboratory rats and mice, with color photomicrographs illustrating examples of some lesions. The standardized nomenclature presented in this document is also available electronically on the internet (http://www.goreni.org/). Sources of material included histopathology databases from government, academia, and industrial laboratories throughout the world. Content includes spontaneous and aging lesions as well as lesions induced by exposure to test materials. There is also a section on normal cyclical changes observed in the ovary, uterus, cervix and vagina to compare normal physiological changes with pathological lesions. A widely accepted and utilized international harmonization of nomenclature for female reproductive tract lesions in laboratory animals will decrease confusion among regulatory and scientific research organizations in different countries and provide a common language to increase and enrich international exchanges of information among toxicologists and pathologists.

Historically, there has been confusion relating to the diagnostic nomenclature for individual cell death. Toxicologic pathologists have generally used the terms single cell necrosis and apoptosis interchangeably. Increased research on the mechanisms of cell death in recent years has led to the understanding that apoptosis and necrosis involve different cellular pathways and that these differences can have important implications when considering overall mechanisms of toxicity, and, for these reasons, the separate terms of apoptosis and necrosis should be used whenever differentiation is possible. However, it is also recognized that differentiation of the precise pathway of cell death may not be important, necessary, or possible in routine toxicity studies and so a more general term to indicate cell death is warranted in these situations. Morphological distinction between these two forms of cell death can sometimes be straightforward but can also be challenging. This article provides a brief discussion of the cellular mechanisms and morphological features of apoptosis and necrosis as well as guidance on when the pathologist should use these terms. It provides recommended nomenclature along with diagnostic criteria (in hematoxylin and eosin [H&E]-stained sections) for the most common forms of cell death (apoptosis and necrosis). This document is intended to serve as current guidance for the nomenclature of cell death for the International Harmonization of Nomenclature and Diagnostic Criteria Organ Working Groups and the toxicologic pathology community at large. The specific recommendations are: Use necrosis and apoptosis as separate diagnostic terms. Use modifiers to denote the distribution of necrosis (e.g., necrosis, single cell; necrosis, focal; necrosis, diffuse; etc.). Use the combined term apoptosis/single cell necrosis when There is no requirement or need to split the processes, or When the nature of cell death cannot be determined with certainty, or When both processes are present together. The diagnosis should be based primarily on the morphological features in H&E-stained sections. When needed, additional, special techniques to identify and characterize apoptosis can also be used

The authors describe a selection of normal findings and common naturally occurring lesions in the reproductive system of female macaques, including changes in the ovaries, uterus, cervix, vagina, and mammary glands. Normal features of immature ovaries, uteri, and mammary glands are described. Common non-neoplastic lesions in the ovaries include cortical mineralization, polyovular follicles, cysts, ovarian surface epithelial hyperplasia, and ectopic ovarian tissue. Ovarian neoplasms include granulosa cell tumors, teratomas, and ovarian surface epithelial tumors. Common non-neoplastic uterine findings include loss of features of normal cyclicity, abnormal bleeding, adenomyosis, endometriosis, epithelial plaques, and pregnancy-associated vascular remodeling. Hyperplastic and neoplastic lesions of the uterus include endometrial polyps, leiomyomas, and rarely endometrial hyperplasia and endometrial adenocarcinoma. Vaginitis is common. Cervical lesions include endocervical squamous metaplasia, polyps, and papillomavirus-associated lesions. Lesions in the mammary gland are most often proliferative and range from ductal hyperplasia to invasive carcinoma. Challenges to interpretation include the normal or pathologic absence of menstrual cyclicity and the potential misinterpretation of sporadic lesions, such as epithelial plaques or papillomavirus-associated lesions. Interpretation of normal and pathologic findings is best accomplished with knowledge of the life stage, reproductive history, and hormonal status of the animal.

The nonrodent species most commonly utilized in preclinical safety studies are the purpose-bred beagle dog and cynomolgus macaque (Macaca fascicularis). Potential effects of a new chemical entity (NCE) on the heart pose serious concerns; consequently in vivo testing is focused on detection of functional alterations as well as morphological changes. Macroscopic and microscopic evaluation of the heart is based on a standard survey of key structures to properly assess presence of spontaneous and potential drug-induced lesions. Evaluation of historical controls to determine type and frequency of background change is valuable, as studies with non-rodent species generally have a small sample size. Archived control dog and monkey data were retrospectively reviewed, including terminal body weight (BW), heart weight (HW), and archival glass slides of heart. Control dogs had minimal background changes that included myxomatous or cartilagenous change in the cardiac skeleton and a variable degree of vacuolation in Purkinje fibers. Control monkey hearts commonly contained inflammatory cell infiltrates, myocyte anisokaryosis, and handling artifacts, while myocyte degeneration, squamous plaques, pigment, and intimal plaques were occasionally observed. These findings highlight the utility of consistently recorded and readily accessible archived control data when attempting to discern background spontaneous changes and artifacts from test-article induced changes.