세포신호와 질병 (2010년 2학기)

연세대학교
구남온

페이스북 트위터 카카오톡 네이버밴드 링크복사

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자연과학 >생물ㆍ화학ㆍ환경 >생명과학
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2010.10.27

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An overview of cell signaling pathways with emphasis on the relationship of function and disease association. In addition to regular classes, two students/each week (~15min/student) will have meetings with a course director to get comments for references described in course syllabus.

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NFkB: NEMO-null mice

차시별 강의

1.	NFkB: NEMO-null mice	- Epithelial NEMO links innate immunity to chronic intestinal inflammation [Nenci A et al. Nature 446:557 (2007)] - Intestinal epithelial-cell-specific inhibition of NF-kB through conditional ablation of NEMO spontaneously caused severe chronic intestinal inflammation in mice. - NF-kB deficiency led to apoptosis of colonic epithelial cells, impaired expression of antimicrobial peptides and translocation of bacteria into the mucosa. - This epithelial defect triggered a chronic inflammatory response in the colon, initially dominated by innate immune cells but later also involving T lymphocytes. - A primary NF-kB signalling defect in intestinal epithelial cells disrupts immune homeostasis in the gastrointestinal tract, causing an inflammatory-bowel-disease-like phenotype.
2.	NFkB: IKKB-null mice	- Opposing functions of IKKB during acute and chronic intestinal inflammation [Eckmann L et al. PNAS 105: 15058 (2008)] - Inhibition of IKKB-dependent NF-kB activation exacerbates acute inflammation, but attenuates chronic inflammatory disease in the intestinal tract. - Acute ulcerating inflammation is aggravated because of diminished NF-kB-mediated protection against epithelial cell apoptosis and delayed mucosal regeneration secondary to reduced NF-kB-dependent recruitment of inflammatory cells that secrete cytoprotective factors. - Ablation of IKKB in the intestinal epithelium has no impact, yet IKKB deficiency in myeloid cells attenuates inflammation and prolongs survival. - These results highlight the striking context and tissue dependence of the proinflammatory and antiapoptotic functions of NF-kB.
3.	p53-Arginine methylation	Arginine methylation regulates the p53 response [Jasson M et al. Nat Cell Biol. 10:1431 (2008)] Protein arginine methyltransferase (PRMT) 5, as a co-factor in a DNA damage responsive co-activator complex that interacts with p53, is responsible for methylating p53. Arginine methylation is regulated during the p53 response and affects the target gene specificity of p53. PRMT5 depletion triggers p53-dependent apoptosis.
4.	p53 variants-p53P72, p53R72	The codon 72 polymorphic variants of p53 have markedly different apoptotic potential [Dumont P et al. Nat Genet. 33:357 (2003)] The gene TP53, encoding p53, has a common sequence polymorphism that results in either proline or arginine at amino-acid position 72. This polymorphism occurs in the proline-rich domain of p53, which is necessary for the protein to fully induce apoptosis. In cell lines containing inducible versions of alleles encoding the Pro72 and Arg72 variants, and in cells with endogenous p53, the Arg72 variant induces apoptosis markedly better than does the Pro72 variant. At least one source of this enhanced apoptotic potential is the greater ability of the Arg72 variant to localize to the mitochondria; this localization is accompanied by release of cytochrome c into the cytosol. The two polymorphic variants of p53 are functionally distinct, and these differences may influence cancer risk or treatment.
5.	Wnt-B-Catenin: Wnt5a signaling in metastatic melanoma	Wnt5a signaling directly affects cell motility and invasion of metastatic melanoma [Weeraratna AT et al. Cancer Cell 1:279 (2002)] Gene expression profiling identified human melanoma cells demonstrating increased cell motility and invasiveness. The gene WNT5A best determined in vitro invasive behavior. Melanoma cells were transfected with vectors constitutively overexpressing Wnt5a. Consistent changes included actin reorganization and increased cell adhesion. No increase in B-catenin expression or nuclear translocation was observed. There was, however, a dramatic increase in activated PKC. In direct correlation with Wnt5a expression and PKC activation, there was an increase in melanoma cell invasion. Blocking this pathway using antibodies to Frizzled-5, the receptor for Wnt5a, inhibited PKC activity and cellular invasion. Furthermore, Wnt5a expression in human melanoma biopsies directly correlated to increasing tumor grade.
6.	Wnt-B-Catenin: Crypt stem cells as the cells-of-origin of intestinal cancer	Crypt stem cells as the cells-of-origin of intestinal cancer [Baker N et al. Nature 457:608 (2009)] Intestinal cancer is initiated by Wnt-pathway-activating mutations in genes such as adenomatous polyposis coli (APC). In a previously established Lgr5 (leucine-rich-repeat containing G-proteincoupled receptor 5) knockin mouse model, a tamoxifen-inducible Cre recombinase is expressed in long-lived intestinal stem cells. Deletion of Apc in these stem cells leads to their transformation within days. Transformed stem cells remain located at crypt bottoms, while fuelling a growing microadenoma. These microadenomas show unimpeded growth and develop into macroscopic adenomas within 3–5 weeks. The distribution of Lgr51 cells within stem-cell-derived adenomas indicates that a stem cell/progenitor cell hierarchy ismaintained in early neoplastic lesions. When Apc is deleted in short-lived transit-amplifying cells using a different cre mouse, the growth of the induced microadenomas rapidly stalls. Even after 30 weeks, large adenomas are very rare in these mice. Stem-cell-specific loss of Apc results in progressively growing neoplasia.
7.	PI3 kinase-Function analisis of p110 mutations	1. Functional Analysis of PIK3CA Gene Mutations in Human Colorectal Cancer [Ikenoue T et al. Cancer Res 65:4562 (2005)]. 2. Cancer-associated p110a mutantions induce a gain of function in p110a (the kinase activity is significantly upregulated). 3. Based on -In vitro PI3K assay -Immunoblot for phosphorylation of well-defined downstream molecules, such as Akt and p70S6K -Transformation assay
8.	PI3 kinase-Mechanism of cancer-associated mutations	1. Mechanism of Two Classes of Cancer Mutations in the Phosphoinositide 3-Kinase Catalytic Subunit [Miled N. et al Science 317:239 (2007)]. 2. Oncogenic mutations in the ABD are not in the interface with the p85 regulatory subunit. 3. p85 inhibition of p110a occurs though a charge-charge interaction between p110a helical domain and p85ni [p110a helical domain oncogenic mutation (such as E545K) disrupts an inhibitory charge-charge interaction with the p85 nSH2].
9.	SAPK-p38α null mice	1. p38a MAP kinase is essential in lung stem and progenitor cell proliferation and differentiation [Ventura JJ et al. Nat Genet. 39:750 (2007)]. 2. p38a positively regulates factors such as CCAAT/enhancer-binding protein that are required for lung cell differentiation. 3. p38a controls self-renewal of the lung stem and progenitor cell population by inhibiting proliferation-inducing signals, most notably epidermal growth factor receptor. 4. Inactivation of p38a leads to an immature and hyperproliferative lung epithelium that is highly sensitized to K-RasG12V-induced tumorigenesis. 5. p38a has a key role in the regulation of lung cell renewal and tumorigenesis.
10.	SAPK-p38δ null mice	1. Regulation of PKD by the MAPK p38d in Insulin Secretion and Glucose Homeostasis [Sumara G et al. Cell 136:235 (2009)]. 2. p38δ null mice display improved glucose tolerance due to enhanced insulin secretion from pancreatic B cells. 3. Deletion of p38d results in pronounced activation of protein kinase D (PKD), a pivotal regulator of stimulated insulin exocytosis. p38d catalyzes an inhibitory phosphorylation of PKD1, thereby attenuating stimulated insulin secretion. 4. p38d null mice are protected against high-fat-feedinginduced insulin resistance and oxidative stressmediated B cell failure. 5. p38d-PKD pathway integrates regulation of the insulin secretory capacity and survival of pancreatic B cells, pointing to a pivotal role for this pathway in the development of overt diabetes mellitus.
11.	14-3-3 protein-zeta	1. 14-3-3ζ Overexpression Defines High Risk for Breast Cancer Recurrence and Promotes Cancer Cell Survival [Neal CL et al. Cancer Res. 69:3425 (2009)]. 2. 14-3-3ζ is overexpressed in >40% of advanced stage breast cancers and is correlated with poor survival in breast cancer patients. 3. 14-3-3ζ overexpression confers cancer cell apoptosis resistance. Increased 4. 14-3-3Z expression enhanced anchorage-independent growth and inhibited stress-induced apoptosis, whereas downregulation of 14-3-3Z reduced anchorage-independent growth and sensitized cells to stress-induced apoptosis via the mitochondrial apoptotic pathway.
12.	14-3-3 protein-sigma	1. 14-3-3σ controls mitotic translation to facilitate cytokinesis [Wilker EW et al. Nature 446:329 (2007)]. 2. 14-3-3s as a regulator of mitotic translation through its direct mitosis-specific binding to a variety of translation/initiation factors, including eukaryotic initiation factor 4B. 3. Cells lacking 14-3-3s cannot suppress cap-dependent translation and do not stimulate cap-independent translation during and immediately after mitosis. 4. This defective switch in the mechanism of translation results in reduced mitotic-specific expression of the endogenous internal ribosomal entry site (IRES)-dependent form of the cyclin-dependent kinase Cdk11 (p58 PITSLRE), leading to impaired cytokinesis, loss of Polo-like kinase-1 at the midbody, and the accumulation of binucleate cells.
13.	CDC25 Phosphatases-Oncogenes	1. CDC25 Phosphatases as Potential Human Oncogenes [Galktionov K et al. Science 269:1575 (1995)] 2. Cyclin-dependent kinases (CDKs) are activated by CDC25 phosphatases, which remove inhibitory phosphate from tyrosine and threonine residues. 3. In rodent cells, human CDC25A or CDC25B but not CDC25C phosphatases cooperate with either Ha-RASGl2v or loss of RB1 in oncogenic focus formation. 4. Such transformants were highly aneuploid, grew in soft agar, and formed high-grade tumors in nude mice. 5. Overexpression of CDC25B was detected in 32 percent of human primary breast cancers tested. 6. The CDC25 phosphatases may contribute to the development of human cancer.
14.	CDC25A Phosphatase-Overexpression in mice	1. Deregulated CDC25A Expression Promotes Mammary Tumorigenesis with Genomic Instability [Ray D et al. Cancer Res 67:984 (2007)] 2. Transgenic expression of CDC25A cooperates markedly with oncogenic ras or neu in murine mammary tumorigenesis. 3. MMTV-CDC25A transgenic mice exhibit alveolar hyperplasia in the mammary tissue but do not develop spontaneous mammary tumors. 4. The MMTVCDC25A transgene markedly shortens latency of tumorigenesis in MMTV-ras mice. 5. The MMTV-CDC25A transgene also accelerates tumor growth inMMTV-neu mice with apparent cell cycle miscoordination. 6. The MMTV-CDC25A transgene also accelerates tumor growth inMMTV-neu mice with apparent cell cycle miscoordination. 7. CDC25A-overexpressing tumors, which invade more aggressively, exhibit various chromosomal aberrations on fragile regions. 8. The chromosomal aberrations account for substantial changes in gene expression profile rendered by transgenic expression of CDC25A, including down-regulation of Trp73. 9. Deregulated control of cellular CDC25A levels leads to in vivo genomic instability, which cooperates with the neu-ras oncogenic pathway in mammary tumorigenesis.
15.	CDK8-Oncogene	1. CDK8 is a colorectal cancer oncogene that regulates B-catenin activity [Firestein R et al. Nature 455:547 (2008)] 2. To identify genes that both modulate b-catenin activity and are essential for colon cancer cell proliferation, we conducted two loss-offunction screens in human colon cancer cells and compared genes identified in these screens with an analysis of copy number alterations in colon cancer specimens. 3. Suppression of CDK8 expression inhibits proliferation in colon cancer cells characterized by high levels of CDK8 and b-catenin hyperactivity. CDK8 kinase activity was necessary for b-catenin-driven transformation and for expression of several b-catenin transcriptional targets. therapeutic 4. Interventions targeting CDK8 may confer a clinical benefit in b-catenin-driven malignancies.
16.	CDK5-Cell cycle suppressor	1. E2F1 represses B-catenin transcription and is antagonized by both pRB and CDK8 [Morris E et al. Nature 455:552 (2008)] 2. E2F1 is a potent and specific inhibitor of b-catenin/T-cell factor (TCF)-dependent transcription, and this function contributes to E2F1-induced apoptosis. 3. E2F1 activity is repressed by cyclin-dependent kinase-8 (CDK8), a colorectal oncoprotein. 4. Elevated levels of CDK8 protect b-catenin/TCF-dependent transcription from inhibition by E2F1. 5. Nuclear localization of Cdk5 is a key determinant in the postmitotic state of neurons [Zang J et al. PNAS 105:8772 (2008)] 6. Cyclin-dependent kinase 5 (Cdk5) is a nontraditional Cdk that is primarily active in postmitotic neurons. 7. In cycling cells, the localization of Cdk5 changes from predominantly nuclear to cytoplasmic as cells reenter a cell cycle after serum starvation. 8. In both human Alzheimer’s disease as well as in the R1.40 mouse Alzheimer’s model and the E2f1 / mouse, neurons expressing cell cycle markers consistently show reduced nuclear Cdk5. 9. Nuclear Cdk5 plays an active role in allowing neurons to remain postmitotic as they mature and loss of nuclear Cdk5 leads to cell cycle entry.