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Human embryonic stem cells in culture possess primary cilia with hedgehog signaling machinery.

ABSTRACT: Human embryonic stem cells (hESCs) are potential therapeutic tools and models of human development. With a growing interest in primary cilia in signal transduction pathways that are crucial for embryological development and tissue differentiation and interest in mechanisms regulating human hESC differentiation, demonstrating the existence of primary cilia and the localization of signaling components in undifferentiated hESCs establishes a mechanistic basis for the regulation of hESC differentiation. Using electron microscopy (EM), immunofluorescence, and confocal microscopies, we show that primary cilia are present in three undifferentiated hESC lines. EM reveals the characteristic 9 + 0 axoneme. The number and length of cilia increase after serum starvation. Important components of the hedgehog (Hh) pathway, including smoothened, patched 1 (Ptc1), and Gli1 and 2, are present in the cilia. Stimulation of the pathway results in the concerted movement of Ptc1 out of, and smoothened into, the primary cilium as well as up-regulation of GLI1 and PTC1. These findings show that hESCs contain primary cilia associated with working Hh machinery.

SUBMITTER: Kiprilov EN

PROVIDER: S-EPMC2265400 | biostudies-literature | 2008 Mar

REPOSITORIES: biostudies-literature

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Human embryonic stem cells in culture possess primary cilia with hedgehog signaling machinery.

Kiprilov Enko N EN Awan Aashir A Desprat Romain R Velho Michelle M Clement Christian A CA Byskov Anne Grete AG Andersen Claus Y CY Satir Peter P Bouhassira Eric E EE Christensen Søren T ST Hirsch Rhoda Elison RE

The Journal of cell biology 20080301 5

Human embryonic stem cells (hESCs) are potential therapeutic tools and models of human development. With a growing interest in primary cilia in signal transduction pathways that are crucial for embryological development and tissue differentiation and interest in mechanisms regulating human hESC differentiation, demonstrating the existence of primary cilia and the localization of signaling components in undifferentiated hESCs establishes a mechanistic basis for the regulation of hESC differentiat ...[more]

PMID: 18332216

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Project description:Background:Primary cilia are small non-motile microtubule and cell membrane protrusions expressed on most vertebrate cells, including cortical and hippocampal neurons. These small organelles serve as sensory structures sampling the extracellular environment and reprogramming the transcriptional machinery in response to environmental change. Primary cilia are decorated with a variety of receptor proteins and are necessary for specific signaling cascades such as the Sonic hedgehog (Shh) pathway. Disrupting cilia structure or function results in a spectrum of diseases collectively referred to as ciliopathies. Common to human ciliopathies is cognitive impairment, a symptom also observed in Alzheimer's disease (AD). One hallmark of AD is accumulation of senile plaques composed of neurotoxic Amyloid-? (A?) peptide. The A? peptide is generated by the proteolytic cleavage of the amyloid precursor protein (APP). We set out to determine if A? affects primary cilia structure and the Shh signaling cascade. Methods:We utilized in vitro cell-based assays in combination with fluorescent confocal microscopy to address our study goals. Shh signaling and cilia structure was studied using two different cell lines, mouse NIH3T3 and human HeLa cells. To investigate how A? levels affect Shh signaling and cilia structure in these cells, we utilized naturally secreted A? as well as synthetic A?. Effects on Shh signaling were assessed by luciferase activity while cilia structure was analyzed by fluorescent microscopy. Results:Here, we report that APP localizes to primary cilia and A? treatment results in distorted primary cilia structure. In addition, we demonstrate that A? treatment interrupts canonical Shh signal transduction. Conclusions:Overall, our study illustrates that A? can alter primary cilia structure suggesting that elevated A? levels, like those observed in AD patients, could have similar effects on neuronal primary cilia in the brain. Additionally, our study suggests that A? impairs the Shh signaling pathway. Together our findings shed light on two novel targets for future AD therapeutics.

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Human embryonic stem cells in culture possess primary cilia with hedgehog signaling machinery.

Publications

Human embryonic stem cells in culture possess primary cilia with hedgehog signaling machinery.

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