A mitotic recombination in Wilms tumor occurs between the parathyroid hormone locus and 11p13

Summary Wilms tumor is believed to occur as the result of two mutations affecting both alleles of a critical gene located within the p13 band of chromosome 11 (Knudson and Strong 1972; Riccardi et al. 1978). Several mechanisms by which these mutations occur have already been determined in retinoblastoma (Cavenee et al. 1983) and Wilms tumor (Koufos et al. 1984; Orkin et al. 1984; Reeve et al. 1984; Fearon et al. 1984a; Eccles et al. 1984). Of the various mechanisms, however, no example of a mitotic recombination was demonstrated in Wilms tumor. An example is presented here which has been detected by the use of restriction fragment length polymorphisms (RFLPs) mapping to chromosome 11p. In addition the data presented are consistent with the mapping location of parathyroid hormone (PTH) being proximal to 11p13.     

Studies on oligosaccharyl transferase in yeast

In yeast, OT consists of nine different subunits, all of which contain one or more predicted transmembrane segments. In yeast, five of these proteins are encoded by essential genes, Swp1p, Wbp1p, Ost2p, Ost1p and Stt3p. Four others are not essential Ost3p, Ost4p, Ost5p, Ost6p. All yeast OT subunits have been cloned and sequenced (Kelleher et al., 1992; 2003; Kelleher & Gilmore, 1997; Kumar et al., 1994; 1995; Breuer & Bause, 1995) and the structure of one of them, Ost4p, has been solved by NMR (Zubkov et al., 2004). Very recently, the preliminary crystal structure of the lumenal domain of an archaeal Stt3p homolog has been reported (Mayumi et al., 2007). Homologs of all OT subunits have been identified in higher eukaryotic organisms (Kelleher et al., 1992; 2003; Kumar et al., 1994; Kelleher & Gilmore, 1997).     

Using isoform-specific inhibitors to target lipid kinases

In this issue of Cell, Knight et al. (2006) present a detailed pharmacological analysis of the PI3 kinase (PI3-K) family using small molecule inhibitors. They conclude that p110alpha, a PI3-K isoform, has a critical role in insulin signaling. In a related Cancer Cell paper, Fan et al. (2006) show that blocking activation of both p110alpha and the kinase mTOR with a small molecule inhibitor limits the growth of gliomas.     

Wild-type p53: tumors can't stand it

Most malignant tumors disrupt the p53 signaling pathway in order to grow and survive. Although many genes in addition to p53 are mutated in tumors, recent studies by Ventura et al. (2007) and Xue et al. (2007) suggest that restoring p53 function alone is sufficient to cause regression of several different tumor types in mice and thus might represent a potent therapeutic strategy to treat certain human cancers. Martins et al. (2006) also demonstrate that restoration of p53 activity results in tumor regression but add the sobering caveat that tumors may be able to quickly generate resistance by finding other ways to disrupt the p53 pathway.     

贵州下寒武统牛蹄塘生物群中海绵新材料

描述了贵州下寒武统牛蹄塘生物群中海绵化石1新属(Zunyispongiagen.nov.),2新种(Zunyispongiatriangulariagen.etsp.nov.,Choiafanensis.sp.nov.),通过对其形态功能的分析和讨论证实了寒武纪早期海绵动物的骨骼是由细小骨针向粗大骨针演变,骨架结构从不稳定型向稳定型发展。     

JAK2 Translocations in hematological malignancies: Review of the literature

JAK2 is a cytoplasmic tyrosine kinase whose gene is located on chromosome 9p24. It is involved in the regulation of different cytokines and growth factors and plays an important role in the diagnosis and treatment of myeloproliferative neoplasms (Smith et al., 2008). Translocations involving the JAK2 locus are uncommon with just a few cases described in the literature, and they usually lead to a fusion protein with JAK2 (Patnaik et al., 2010). Chromosome 9p24 abnormalities have been described in myeloid and lymphoid neoplasms including chronic myelogenous leukemia (CML), acute megakaryoblastic leukemia, CD10+ B-cell acute lymphoblastic leukemia, T-cell ALL and chronic myeloproliferative disorders (CMD) (Smith et al., 2008; Lacronique et al., 1997). Although the breakpoints of each translocation are known, characterization of the partner gene has not been done in many of the cases reported due to insufficient sample or other factors. In the present study we review all translocations involving JAK2 that have been reported in the literature.     

Maximum likelihood estimation of ordered multinomial parameters

The pool adjacent violator algorithm Ayer et al. (1955, The Annals of Mathematical Statistics, 26, 641-647) has long been known to give the maximum likelihood estimator of a series of ordered binomial parameters, based on an independent observation from each distribution (see Barlow et al., 1972, Statistical Inference under Order Restrictions, Wiley, New York). This result has immediate application to estimation of a survival distribution based on current survival status at a set of monitoring times. This paper considers an extended problem of maximum likelihood estimation of a series of 'ordered' multinomial parameters p(i)= (p(1i),p(2i),.,p(mi)) for 1 相似文献   

Yos9p: a sweet-toothed bouncer of the secretory pathway

In this issue of Molecular Cell, Bhamidipati et al., (2005) and Kim et al., (2005), and Szathmary et al. (2005), and demonstrate that Yos9p selectively binds to aberrant glycoproteins in the endoplasmic reticulum (ER) and targets them for destruction through the ER-associated protein degradation pathway.     

Lack of an Additive Effect between the Deletions of Klf5 and Nkx3-1 in Mouse Prostatic Tumorigenesis

Prostate cancer is one of the most common malignancies.The development and progression of prostate cancer are driven by a series of genetic and epigenetic events including gene amplification that activates oncogenes and chromosomal deletion that inactivates tumor suppressor genes.Whereas gene amplification occurs in human prostate cancer,gene deletion is more common,and a large number of chromosomal regions have been identified to have frequent deletion in prostate cancer,suggesting that tumor suppressor inactivation is more common than oncogene activation in prostatic carcinogenesis (Knuutila et al.,1998,1999;Dong,2001).Among the most frequently deleted chromosomal regions in prostate cancer,target genes such as NKX3-1 from 8p21,PTENfrom 10q23 andATBF1 from 16q22 have been identified by different approaches (He et al.,1997;Li et al.,1997;Sun et al.,2005),and deletion of these genes in mouse prostates has been demonstrated to induce and/or promote prostatic carcinogenesis.For example,knockout of Nkx3-1 in mice induces hyperplasia and dysplasia (Bhatia-Gaur et al.,1999;Abdulkadir et al.,2002) and promotes prostatic tumorigenesis (Abate-Shen et al.,2003),while knockout of Pten alone causes prostatic neoplasia (Wang et al.,2003).Therefore,gene deletion plays a causal role in prostatic carcinogenesis (Dong,2001).     

Living with p53, dying of p53

The p53 tumor suppressor protein acts as a major defense against cancer. Among its most distinctive features is the ability to elicit both apoptotic death and cell cycle arrest. In this issue of Cell, Das et al. (2007) and Tanaka et al. (2007) provide new insights into the mechanisms that dictate the life and death decisions of p53.     

New Phytologist 140 (1998), 363–383

In the November 1998 issue of New Phytologist , we published the Tansley review 'Gibberellins: regulating genes and germination' by Sian Ritchie and Simon Gilroy ( New Phytol. (1998) 140 , 363–383). Since its publication, it has come to our attention that text associated with Fig. 4 was omitted during production. The correct figure is reprinted here in full.
We apologise to the author and to our readers for this mistake.
Figure 4. Promoter sequences of various genes expressed in the cereal aleurone and shown to be regulated by GA. The position of each sequence is indicated relative to the start codon. Regions identified as being involved in regulation of the genes are highlighted, as are similar regions in other genes. Sites at which protein has been shown to bind are also indicated. ( a ) Barley Amy 32b (Sutcliff et al ., 1993; Whittier et al ., 1987); wheat Amy 2/54 (Huttley et al ., 1992; Rushton et al ., 1992; Rushton et al ., 1995); barley Amy 46 (Khursheed & Rogers, 1988); barley Amy 2/p155 (Knox et al ., 1987); barley aleurain (Whittier et al ., 1987); barley β-glucanase II (Wolf, 1992); wheat cathepsin B-like (Cejudo et al ., 1992); rice ubiquitin-conjugating enzyme (Chen et al ., 1995). ( b ). Wheat Amy 1/18 (Rushton et al ., 1992); barley Amy pHV 19 (Jacobsen & Close, 1991; Gubler & Jacobsen, 1992)/ Amy 1 / 6-4 (Khursheed & Rogers, 1988; Rogers, Lanahan & Rogers 1994); rice OSamy-a / Amy 3c (Ou-Lee et al ., 1988; Sutcliff et al ., 1991; Yu et al ., 1992; Goldman et al ., 1994); rice Amy 3B (Sutcliffe et al ., 1991); rice OSamy-c (Kim et al ., 1992; Kim & Wu, 1992; Tanida et al ., 1994); rice Amy 1A (Huang et al ., 1990; Itoh et al ., 1995).
Figure 4 ( b ). For legend see facing page.     

64 Hoogsteen or not Hoogsteen? Iodine-125 radioprobing of the p53-induced DNA deformations

Radioprobing is suitable for tracing the DNA and RNA trajectories in nucleoprotein complexes in solution. The method is based on the analysis of the single-strand breaks produced by decay of iodine-125 incorporated in the C5 position of cytosine (Karamychev et al., 1999, 2012). Here, we used radioprobing to study the conformation of DNA in complex with the DNA binding domain (DBD) of the tumor-suppressor protein p53. Two recently crystallized DNA-p53 DBD complexes have different conformations of the CATG motifs: one with the Hoogsteen A:T pairs (Kitayner et al., 2010) and the other with the Watson–Crick pairs (Chen et al., 2010). The two complexes differ in the sequence of the central YYY|RRR junction: the first one has the C|G step and the second has the T|A step. Thus, it is interesting to apply the radioprobing method to the two DNA sequences used in crystallography to see if the local changes (T|A to C|G) in the center of the p53 response element would produce significant distortions in the CATG motifs. To this aim, the iodine-containing cytosine was incorporated in the duplexes containing p53-binding sites, in one of the two CATG motifs and the frequencies of DNA breaks were analyzed. Frequencies of breaks are negatively correlated with the iodine–sugar distances, thus, one can evaluate the changes in these distances upon DNA binding to a protein. The radioprobing distances obtained for both DNA sequences proved to be consistent with the Watson–Crick structure observed by Chen et al. (2010). We did not find any evidence of the Hoogsteen A:T base pair formation in the DNA-p53 DBD complexes in solution using our radioprobing method. The most significant changes in the break frequency distributions were detected in the central segment of the p53 binding site, YYY|RRR, which are consistent with an increase in DNA twisting in this region and local DNA bending and sliding (Nagaich et al., 1999). We interpret these p53-induced DNA deformations in the context of p53 binding to nucleosomal DNA (Sahu et al., 2010).     

The p7 protein of hepatitis C virus forms an ion channel that is blocked by the antiviral drug,Amantadine

Hepatitis C virus (HCV) cannot be grown in vitro, making biochemical identification of new drug targets especially important. HCV p7 is a small hydrophobic protein of unknown function, yet necessary for particle infectivity in related viruses [Harada, T. et al., (2000) J. Virol. 74, 9498-9506]. We show that p7 can be cross-linked in vivo as hexamers. Escherichia coli expressed p7 fusion proteins also form hexamers in vitro. These and HIS-tagged p7 function as calcium ion channels in black lipid membranes. This activity is abrogated by Amantadine, a compound that inhibits ion channels of influenza [Hay, A.J. et al. (1985) EMBO J. 4, 3021-3024; Duff, K.C. and Ashley, R.H. (1992) Virology 190, 485-489] and has recently been shown to be active in combination with current HCV therapies.     

Centrosome amplification as a possible mechanism for numerical chromosome aberrations in cerebral primitive neuroectodermal tumors with TP53 mutations

Although alterations in chromosome number have frequently been detected in human tumor cells and associated with tumor initiation and progression, the causal mechanisms are still not understood. One protein known to be involved in maintaining genetic stability is tumor suppressor p53. In mice, p53 has been implicated in the maintenance of diploidy (Cross et al., 1995) and the regulation of centrosome duplication (Fukasawa et al., 1996). Here we report on cerebral primitive neuroectodermal tumors that lacked the wild-type p53 gene (TP53) and showed multiple numerical chromosome aberrations, as detected by comparative genomic hybridization. In these tumors, the centrosome number was significantly higher than in a control tumor without a detected TP53 mutation and with few chromosomal imbalances. These findings indicate that abnormal centrosome amplification can occur in human tumors lacking wild-type TP53 and may be a mechanism by which numerical chromosome aberrations are generated.     

‘Complete’ trisomy 5p; de novo translocation t(2;5)(q36;p11) with isochromosome 5p

Summary A case of complete trisomy 5p due to a de novo translocation t(2;5)(q36;p11) with an isochromosome 5p is described. Complete trisomy 5p has been reported only once (Brimblecombe et al., 1977). The confusing literature relating to partial trisomy 5p is reviewed. Comparison of our case with the patients reported by Brimblecombe et al. (1977) and by Opitz and Patau (1975) is suggestive for a distinct clinical syndrome if (almost) the complete short arm of chromosome 5 is present in a trisomic state. Unfortunately the clinical findings in the case of Brimblecombe (1966, 1977) are poorly documented. The main features of this syndrome are: macrocephaly, psychomotor retardation, hypotonia, postnatal growth failure, tracheobronchial involvement, mongoloid slant of the eyes, epicanthus, low-set ears, depressed nasal bridge, short first toe, and seizures.     

Two forms of DNA polymerase delta from mouse cells. Purification and properties

A procedure is described for the purification from cultured mouse cells of two DNA polymerase "delta-like" enzymes, as defined by intrinsic 3'-exonuclease activity, inhibition by aphidicolin, and relative insensitivity to N2-(p-n-butylphenyl)-dGTP. One of the two enzymes has been purified to near homogeneity and, similar to the DNA polymerase delta from calf thymus described by Lee et al. (Lee, M. Y. W. T., Tan, C. K., Downey, K. M., and So, A. G. (1984) Biochemistry 23, 1906-1913), it has a total molecular mass of 178 kDa (from sedimentation velocity of 8.0 S and Stokes radius of 54 A) and is composed of one each of 125- and 50-kDa polypeptides. It also resembles the DNA polymerase delta of Lee et al. in being stimulated by proliferating cell nuclear antigen (PCNA). It is the first clear structural and functional counterpart of the calf thymus enzyme. The major difference between the mouse DNA polymerase delta and the calf thymus enzyme of Lee et al. is that, under specific conditions, the mouse enzyme is active with poly(dA).oligo(dT) in the absence of PCNA, whereas the activity of the calf thymus enzyme with this template is reported to be completely dependent on PCNA. The reason for this difference is not known at this time. The second mouse cell enzyme has a molecular mass of 112 kDa (from sedimentation velocity of 6.3 S and Stokes radius of 43.0 A) and consists of a single polypeptide of 123-125 kDa in denaturing gels (p125). On the basis of its apparent formation by dissociation of DNA polymerase delta, and multiple similarities with DNA polymerase delta in enzymatic properties, the p125 is provisionally identified as the 125-kDa polypeptide of DNA polymerase delta. The p125 does not respond to PCNA, suggesting that the 50-kDa polypeptide is required for the stimulation of DNA polymerase delta by PCNA. The presence of the p125 in cell extracts would explain reports that DNA polymerase delta consists of a single polypeptide of approximately 125 kDa and/or thast it has a smaller molecular mass than DNA polymerase delta of Lee et al. and is not affected by PCNA (this does not apply to PCNA-independent DNA polymerase delta-like enzymes with higher molecular mass than the polymerase delta of Lee et al., which have recently been named DNA polymerases epsilon).     

Genetic signatures of strong recent positive selection at the lactase gene

In most human populations, the ability to digest lactose contained in milk usually disappears in childhood, but in European-derived populations, lactase activity frequently persists into adulthood (Scrimshaw and Murray 1988). It has been suggested (Cavalli-Sforza 1973; Hollox et al. 2001; Enattah et al. 2002; Poulter et al. 2003) that a selective advantage based on additional nutrition from dairy explains these genetically determined population differences (Simoons 1970; Kretchmer 1971; Scrimshaw and Murray 1988; Enattah et al. 2002), but formal population-genetics-based evidence of selection has not yet been provided. To assess the population-genetics evidence for selection, we typed 101 single-nucleotide polymorphisms covering 3.2 Mb around the lactase gene. In northern European-derived populations, two alleles that are tightly associated with lactase persistence (Enattah et al. 2002) uniquely mark a common (~77%) haplotype that extends largely undisrupted for >1 Mb. We provide two new lines of genetic evidence that this long, common haplotype arose rapidly due to recent selection: (1) by use of the traditional F(ST) measure and a novel test based on p(excess), we demonstrate large frequency differences among populations for the persistence-associated markers and for flanking markers throughout the haplotype, and (2) we show that the haplotype is unusually long, given its high frequency--a hallmark of recent selection. We estimate that strong selection occurred within the past 5,000-10,000 years, consistent with an advantage to lactase persistence in the setting of dairy farming; the signals of selection we observe are among the strongest yet seen for any gene in the genome.