Converting human skin cells to neurons: a new tool to study and treat brain disorders?

Recent publications in Cell Stem Cell (Son et?al., 2011; Ambasudhan et?al., 2011), PNAS (Pfisterer et?al., 2011), and Nature (Caiazzo et?al., 2011; Pang et?al., 2011; Yoo et?al., 2011) report that functional neurons can be directly generated from human fibroblast cells without going through the pluripotent state.     

Breaking the cell cycle of HSCs by p57 and friends

The cell cycle regulators involved in maintaining the quiescence, and thereby the self-renewal capacity, of somatic stem cells have long been elusive. Two new Cell Stem Cell articles in this issue (Matsumoto et?al., 2011; Zou et?al., 2011) now show that the CDK inhibitor p57 is a crucial brake for cycling HSCs, and links self-renewal activity to cell cycle quiescence.     

Stem Cells and β Cells: The Same,but Different?

Researchers have long debated whether new pancreatic β cells derive from stem cells or from pre-existing β cells. A new study in this issue of Cell Stem Cell (Smukler et al., 2011) suggests that both sides may be right.     

Moving right along: how PP1 helps clear the checkpoint

Spindle checkpoint silencing is crucial for cell-cycle progression, but mechanisms underlying this process remain mysterious. Two papers, one in this issue of Developmental Cell (Meadows et?al., 2011) and one in Current Biology (Rosenberg et?al., 2011), begin to show how phosphatase PP1-gamma connects chromosome-microtubule attachment with anaphase entry.     

A hormone sends instant messages to the genome

Accurate chromosome segregation during mitosis and meiosis is essential for cell viability. Two papers in this issue of Cell (Kitajima et al., 2011; Magidson et al., 2011) describe chromosome movements during cell division with unprecedented accuracy, revealing previously unrecognized features of chromosome spindle alignment and paving the way to quantitative phenotypic and mechanistic analyses of chromosome alignment during prometaphase.     

Converted neural cells: induced to a cure?

Many neurodegenerative disorders such as Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS) and others often occur as a result of progressive loss of structure or function of neurons. Recently, many groups were able to generate neural cells, either differentiated from induced pluripotent stem cells (iPSCs) or converted from somatic cells. Advances in converted neural cells have opened a new era to ease applications for modeling diseases and screening drugs. In addition, the converted neural cells also hold the promise for cell replacement therapy (Kikuchi et al., 2011; Krencik et al., 2011; Kriks et al., 2011; Nori et al., 2011; Rhee et al., 2011; Schwartz et al., 2012). Here we will mainly discuss most recent progress on using converted functional neural cells to treat neurological diseases and highlight potential clinical challenges and future perspectives.     

iPSCs: induced back to controversy

Several recent reports (Mayshar et?al., 2010; Laurent et?al., 2011; Lister et?al., 2011; Gore et?al., 2011; Hussein et?al., 2011) uncover genetic and epigenetic alterations in induced pluripotent stem cells, stimulating debate about their future. However, will these important findings really impact what we hope to gain?     

Tolerance induction by allogeneic hematopoietic stem cells

In this issue of Cell Stem Cell, Zheng et?al. (2011) report that HSCs expressing PD-L1 display enhanced engraftment in irradiated allogeneic recipients. Independently in Nature, Fujisaki et?al. (2011) observe allogeneic HSCs persisting in proximity to regulatory T?cells in nonirradiated recipients, further connecting HSCs and immune tolerance.     

Shigella targets T cells

Using a syringe-like device, Shigella delivers an array of virulence factors into host cells to facilitate bacterial colonization and disable the host's innate immune defense. In this issue of Cell Host & Microbe, Konradt and colleagues (Konradt et al., 2011) show that Shigella also subverts adaptive immunity by targeting T cells through a mechanism involving PIP(2) breakdown.     

Haploid embryonic stem cells and the dominance of recessive traits

Diploidy, though essential for normal development, is a foil to geneticists. Two recent studies (Elling et?al., 2011, this issue of Cell Stem Cell; Leeb and Wutz, 2011, Nature), report the isolation of haploid pluripotent mouse ESCs, thus enabling efficient functional screening for genes involved in diverse cellular and developmental processes.     

Food for thought: neural stem cells on a diet

Growing evidence shows that stem cells are modulated by systemic factors that are integrated with local signals in response to physiological status. Two recent Cell (Chell and Brand, 2010) and Nature (Sousa-Nunes et?al., 2011) papers reveal that Drosophila neural stem cell proliferation is controlled by a diet-dependent insulin/TOR signaling relay between tissues.     

Glucose as a mitogenic hormone

Glucose stimulates insulin secretion in β cells, which sense glucose concentrations through signals derived from glycolytic metabolism. In this issue of Cell Metabolism, Dor and colleagues (Porat et al., 2011) combine genetic, transplantation, and pharmacologic approaches to show that glucose also stimulates β cell proliferation through similar metabolic signals, providing a new framework to develop therapeutics for diabetes.     

Smac mimetics and TNFalpha: a dangerous liaison?

Inhibitor of apoptosis proteins (IAPs) such as XIAP, cIAP1, and cIAP2 are upregulated in many cancer cells. It has been thought that small-molecule mimetics of Smac, an endogenous IAP antagonist, might potentiate apoptosis in cancer cells by promoting caspase activation. However, three recent papers, two in Cell (Vince et al., 2007; Varfolomeev et al., 2007) and one in Cancer Cell (Petersen et al., 2007), now report that Smac mimetics primarily kill cancer cells via a different mechanism, the induction of autoubiquitination and degradation of cIAPs, which culminates in TNFalpha-mediated cell death.     

Cortex shatters the glass ceiling

Recreating developmental structures in vitro has been a primary challenge for stem cell biologists. Recent studies in Cell Stem Cell (Eiraku et al., 2008) and Nature (Gaspard et al., 2008) demonstrate that embryonic stem cells can recapitulate early cortical development, enabling them to generate specific cortical subtypes.     

Gimme phospho-serine five! Capping enzyme guanylyltransferase recognition of the RNA polymerase II CTD

In this issue of Molecular Cell, two papers on the structure of murine capping enzyme guanylyltransferase (Ghosh et?al., 2011) and yeast studies of the recognition of the RNA polymerase II CTD (Schwer and Shuman, 2011) describe the mechanism of recruitment of the capping apparatus to nascent pre-mRNAs.     

Myotonic Muscular Dystrophy,RNA Toxicity,and the Brain: Trouble Making the Connection?

The study of rare genetic diseases is complicated by the inaccessibility of relevant cells and tissues, especially for neurologic disorders. In this issue of Cell Stem Cell, Marteyn et?al. (2011) use human embryonic stem cells to identify deficits in neuritic outgrowth in myotonic dystrophy type 1.     

Epicardial origin of cardiac CFU-Fs

The epicardium has been recognized as a source of cardiovascular progenitors during embryogenesis and postnatal life. In this issue of Cell Stem Cell, Chong et al. (2011) identify cardiac CFU-Fs as cardiac-resident cells of epicardial origin with broad multilineage differentiation potential.     

ATM signals miRNA biogenesis through KSRP

In this issue of Molecular Cell, Zhang and colleagues (Zhang et?al., 2011) describe a critical link between the DNA damage response and the miRNA pathway, in which DNA double-strand breaks (DSBs) induce ATM-dependent KSRP phosphorylation to facilitate pri-miRNA processing.