The role of MDM2 and MDM4 in breast cancer development and prevention

The major cause of death from breast cancer is not the primary turnout, but relapsing, drug-resistant, metastatic disease. Identifying factors that contribute to aggressive cancer offers important leads for therapy. Inherent defence against carcinogens depends on the individual molecular make-up of each person. Important molecular determinants of these responses are under the control of the mouse double minute （MDM） family： comprised of the proteins MDM2 and MDM4. In normal, healthy adult cells, the MDM family functions to critically regulate measured, cellular responses to stress and subsequent recovery. Proper function of the MDM family is vital for normal breast development, but also for preserving genomic fidelity. The MDM family members are best characterized for their negative regulation of the major tumour suppressor p53 to modulate stress responses. Their impact on other cellular regulators is emerging. Inappropriately elevated protein levels of the MDM family are highly associated with an increased risk of cancer incidence. Exploration of the MDM family members as cancer therapeutic targets is relerant for designing tailored anti-cancer treatments, but successful approaches must strategically consider the impact on both the target cancer and adjacent healthy ceils and tissues. This review focuses on recent findings pertaining to the role of the MDM family in normal and malignant breast cells.

Parkinson's disease: From genetics to molecular dysfunction and targeted therapeutic approaches

Parkinson's disease (PD) is the most common neurodegenerative movement disorder in the elderly. As the pathogenesis of PD is still not fully understood, medications with the capacity of halting the disease progression are currently unavailable. The discovery of genes that are causative for, or increase susceptibility to PD is pivotal for the development of novel therapeutic approaches, as they are critical for the onset of PD and the molecular pathways underlying its pathogenesis. By reviewing relevant data, we discuss causative genes, and those associated with PD susceptibility and quantitative traits. Through Gene Ontology database and STRING analysis, we emphasize the roles of inorganic cation transmembrane transport pathways and hypothalamic pituitary thyroid axis, in addition to the established roles of inflammation/oxidative stress and mitochondrial dysfunction in the pathogenesis of PD. It is hoped these insights 1) untangle the clinical complex presentations of PD, 2) reveal the interwoven molecular network leading to PD, and 3) identify critical molecular targets to facilitate novel PD drug discovery, with a view to providing improved consultation and personalized medicine for patients with PD in the future.

Claudin-11 and occludin are major contributors to Sertoli cell tight junction function, in vitro

The Sertoli cell tight junction （T J） is the key component of the blood-testis barrier, where it sequesters developing germ cells undergoing spermatogenesis within the seminiferous tubules. Hormonally regulated claudin-11 is a critical transmembrane protein involved in barrier function and its murine knockout results in infertility. We aimed to assess quantitatively the significance of the contribution of claudin-11 to TJ function, in vitro, using siRNA-mediated gene silencing. We also conducted an analysis of the contribution of occludin, another intrinsic transmembrane protein of the TJ. Silencing of claudin-11 and/or occludin was conducted using siRNA in an immature rat Sertoli cell culture model. Transepithelial electrical resistance was used to assess quantitatively TJ function throughout the culture. Two days after siRNA treatment, cells were fixed for immunocytochemical localization of junction proteins or lyzed for RT-PCR assessment of mRNA expression. Silencing of claudin-11, occludin, or both resulted in significant decreases in TJ function of 55% （P 〈 0.01）, 51% （P 〈 0.01）, and 62% （P 〈 0.01）, respectively. Data were concomitant with significant decreases in mRNA expression and marked reductions in the localization of targeted proteins to the Sertoli cell TJ. We provide quantitative evidence that claudin-11 contributes significantly （P 〈 0.01） to Sertoli cell TJ function in vitro. Interestingly, occludin, which is hormonally regulated but not implicated in infertility until late adulthood, is also a significant （P 〈 0.01） contributor to barrier function. Our data are consistent with in vivo studies that clearly demonstrate a role for these proteins in maintaining normal TJ barrier structure and function.