Cystic fibrosis transmembrane conductance regulator splice variants are not conserved and fail to produce chloride channels.

In the human CFTR only the rare exon 4- splice variant is conserved in mice. We have discovered two novel murine variants, exon 5- and exon 11b+. The exon 5- variant represents up to 40% of mRNA in all CFTR-expressing tissues and leaves the reading frame intact. The exon 11b+ variant inserts a novel exon between exons 11 and 12 with expression restricted to the testis. Two variants of 11b have been found and both introduce premature stop codons. When we expressed human CFTR variants lacking either exon 5 or exon 9 in HeLa cells, they failed to generate cAMP-mediated chloride transport, due to defective intracellular processing. The lack of conservation of splice variants between species and the inability of the more abundant splice variants to generate protein that is correctly processed argue against a physiological role and may simply represent aberrant splicing that is tolerated by the cell and organism.

The biomechanics of maintaining effective force application across cycling positions.

Cyclists are known to change their cycling position to reduce aerodynamic drag. Research has shown that this compromises their physical capacity to perform, but there is considerable inter-individual variability present. Proposed training specificity effects by cycling position do not explain all of the observations in the literature, so a search for other influencing parameters is warranted and might help practitioners to further optimise cycling position. This study captured full-body kinematics and 2D crank forces in 19 Time-Trial (TT) and 36 Road trained cyclists. Data in preferred and standardised cycling positions were systematically evaluated and showed that, amongst other kinematic differences, TT cyclists prefer a more forwardly positioned hip joint over Road cyclists. Despite their different setup, no effects in mechanical effectiveness were seen between the groups when tested in their preferred position. Across the standardised positions, the full cohort showed lower mechanical effectiveness when lowering trunk angle. However, significant group by position interactions showed this effect to be less extreme for the TT group. Kinematic data revealed that an increased pelvic tilt resulted in increased hip flexion and induced a more dorsiflexed ankle angle. In addition, linear hip position acutely responded to positional changes by moving forwards when the trunk angle was lowered. A more forwards hip position is thus associated with maintaining a better mechanical effectiveness in aerodynamic cycling positions. This suggests that there is potential to mitigate the effect of negative crank forces in aerodynamic positions by acutely adjusting the saddle placement to facilitate linear hip movement.

Microdissection of and microcloning from the short arm of human chromosome 2.

A bank of cloned DNA sequences from the distal half of the short arm of human chromosome 2 was generated by using microdissection and microcloning techniques. DNA was purified from 106 chromosomal fragments, manually dissected from peripheral lymphocytes in metaphase, and cloned into the EcoRI site of lambda gt10. A total of 257 putative recombinants were recovered, of which 41% were found to contain human inserts. The mean insert size was 380 base pairs (median size, 83 base pairs), and fewer than 10% of the clones contained highly repetitive sequences. All single-copy sequences examined were shown to map to the short arm of chromosome 2 by using hybrid panels. This technique provides a rapid method of isolating probes specific to a human subchromosomal region to generate linked markers to genetic diseases for which the chromosomal location is known.

A compartmentalized phosphoinositide signaling axis at cilia is regulated by INPP5E to maintain cilia and promote Sonic Hedgehog medulloblastoma.

Sonic Hedgehog (SHH) signaling at primary cilia drives the proliferation and progression of a subset of medulloblastomas, the most common malignant paediatric brain tumor. Severe side effects associated with conventional treatments and resistance to targeted therapies has led to the need for new strategies. SHH signaling is dependent on primary cilia for signal transduction suggesting the potential for cilia destabilizing mechanisms as a therapeutic target. INPP5E is an inositol polyphosphate 5-phosphatase that hydrolyses PtdIns(4,5)P2 and more potently, the phosphoinositide (PI) 3-kinase product PtdIns(3,4,5)P3. INPP5E promotes SHH signaling during embryonic development via PtdIns(4,5)P2 hydrolysis at cilia, that in turn regulates the cilia recruitment of the SHH suppressor GPR161. However, the role INPP5E plays in cancer is unknown and the contribution of PI3-kinase signaling to cilia function is little characterized. Here, we reveal INPP5E promotes SHH signaling in SHH medulloblastoma by negatively regulating a cilia-compartmentalized PI3-kinase signaling axis that maintains primary cilia on tumor cells. Conditional deletion of Inpp5e in a murine model of constitutively active Smoothened-driven medulloblastoma slowed tumor progression, suppressed cell proliferation, reduced SHH signaling and promoted tumor cell cilia loss. PtdIns(3,4,5)P3, its effector pAKT and the target pGSK3ß, which when non-phosphorylated promotes cilia assembly/stability, localized to tumor cell cilia. The number of PtdIns(3,4,5)P3/pAKT/pGSK3ß-positive cilia was increased in cultured Inpp5e-null tumor cells relative to controls. PI3-kinase inhibition or expression of wild-type, but not catalytically inactive HA-INPP5E partially rescued cilia loss in Inpp5e-null tumor cells in vitro. INPP5E mRNA and copy number were reduced in human SHH medulloblastoma compared to other molecular subtypes and consistent with the murine model, reduced INPP5E was associated with improved overall survival. Therefore our study identifies a compartmentalized PtdIns(3,4,5)P3/AKT/GSK3ß signaling axis at cilia in SHH-dependent medulloblastoma that is regulated by INPP5E to maintain tumor cell cilia, promote SHH signaling and thereby medulloblastoma progression.

Medulloblastomas of the desmoplastic variant carry mutations of the human homologue of Drosophila patched.

Inactivating mutations in the PTCH gene, a human homologue of the Drosophila segment polarity gene patched, have been identified recently in patients with nevoid basal cell carcinoma syndrome. These patients are predisposed to various neoplasias including basal cell carcinomas and medulloblastomas (MBs). To determine the involvement of PTCH in sporadic MBs, which represent the most frequent malignant brain tumors in children, we screened for PTCH alterations in an unselected panel of 64 biopsy samples from 62 patients and four continuous MB cell lines, all derived from patients with sporadic MBs. Using single-strand conformational polymorphism analysis, we screened exons 2-22 and detected nonconservative PTCH mutations in 3 of 11 samples from sporadic cases of the desmoplastic variant of MB but none in 57 MBs with classical (nondesmoplastic) histology. In two of the tumors with mutations and in two additional desmoplastic cases, loss of heterozygosity was found at 9q22. These findings suggest that PTCH represents a tumor suppressor gene involved in the development of the desmoplastic variant of MB.

Murine WNT11 is a secreted glycoprotein that morphologically transforms mammary epithelial cells.

Wnt genes encode a set of structurally related cell surface glycoproteins that appear to have roles in cell-cell signalling. The ectopic expression of several murine Wnt genes has been implicated in the transformation of mammary epithelial and the onset of mammary tumours. Wnt11 is expressed in the developing embryo in a variety of structures including the dermatome/myotome junction of the somites, the truncus ateriosus region of the heart and limb mesenchyme. Here we report that Wnt11 encodes a glycoprotein that is secreted from expressing cells and becomes associated with the extracellular matrix. In addition, Rat2 fibroblasts expressing WNT11 (which are not morphologically altered themselves) are able to induce the transformation of adjacent C57MG mammary epithelial cells in co-culture experiments. These results suggest that WNT11 functions via a paracrine signalling mechanism to have a direct effect on the morphology and growth characteristics of mammary epithelial cells.

A novel target for the Wilms' tumour suppressor protein (WT1) is bound by a unique combination of zinc fingers.

All isoforms of the Wilms' tumour suppressor protein, WT1, contain four consecutive zinc fingers which facilitate DNA binding. The predominant WT1 transcript contains a 9 base pair insertion resulting in an additional three amino acids, lysine-threonine-serine (KTS), between zinc fingers 3 and 4. WT1 zinc fingers 2, 3 and 4 are highly homologous to the zinc fingers of the early growth response gene, EGR1. However, only WT1--KTS is capable of binding an EGR1 consensus site. In contrast, the previously described genomic fragment, +P5 (D1S3309E), is bound by both WT1--KTS and WT1 + KTS. In this study, the region within + P5 to which both WT1 -- KTS and WT1 + KTS bind was defined as 5'-GGAGAGGGAGGATC-3'. EGR1 did not bind + P5. By creating zinc finger deletions, we demonstrate that zinc finger 1, but not zinc finger 4, is critical for + P5 binding; whereas zinc finger 4, but not 1, is necessary for the binding of WT1 target sites within EGR1, PDGF A chain and IGF2 promoters. Thus, zinc finger usage can vary with target and + P5 may represent a novel type of WT1 binding site, the physiological relevance of which must be investigated.

CDX2, a human homologue of Drosophila caudal, is mutated in both alleles in a replication error positive colorectal cancer.

The Cdx2 gene is one of three murine homologues of the Drosophila homeobox gene caudal. Mice heterozygous for a null mutation in Cdx2 exhibit a variable phenotype including tail abnormalities, stunted growth and a homeotic shift of vertebrae. Most strikingly, however, 90% of heterozygous mice were reported to develop multiple intestinal adenomatous polyps, most notably in the proximal colon (Chawengsaksophak et al., 1997). These observations led us to propose that mutation of CDX2 may be involved in the genesis of some human colorectal tumours. A survey of DNA from 85 colorectal tumours revealed that one with extensive microsatellite instability (RER+ phenotype) has mutations in both alleles of CDX2. Both mutations occur in coding regions which contain repetitive elements and are consistent with those found in RER + tumours.

No evidence for the H133Y mutation in SONIC HEDGEHOG in a collection of common tumour types.

The human homologue of the Drosophila segment polarity gene patched is mutated in the cancer predisposition syndrome naevoid basal cell carcinoma syndrome (NBCCS), as well as in several types of tumour associated with the disorder. It was recently reported that a single recurrent mutation in the SONIC HEDGEHOG gene, which encodes the PATCHED ligand, was found in one of 43 basal cell carcinomas (BCCs), one of 14 medulloblastomas and one of six breast carcinomas analysed (Oro et al., 1997). We have searched extensively for this same mutation in a large collection of BCCs, medulloblastomas and carcinomas of the breast, ovary and colorectum and have failed to detect the mutation in any sample analysed.

DHPLC analysis of patients with Nevoid Basal Cell Carcinoma Syndrome reveals novel PTCH missense mutations in the sterol-sensing domain.

Nevoid Basal Cell Carcinoma Syndrome (NBCCS) is an autosomal dominant disorder characterised by multiple basal cell carcinomas, palmar and plantar pitting, odontogenic keratocysts of the jaws and bilamellar calcification of the falx. Mutations in the PTCH gene are responsible for NBCCS but most studies have found mutations in less than half of the cases tested. We used denaturing high performance liquid chromatography (DHPLC) to screen for PTCH mutations in 28 NBCCS cases, most of whom had been previously evaluated by single stranded conformation polymorphism analysis but found to be negative. Protein truncating (n = 10) and missense or indel (n = 4) mutations were found in 14/28 (50%) cases and one additional case carried an unclassified variant, c.2777G>C. Thirteen of the variants were novel. The mutation frequency was similar in inherited and de novo cases. Three of the missense and indel mutations were in the sterol-sensing domain, and one was in the sixth transmembrane domain.

Novel susceptibility gene for late-onset NIDDM is localized to human chromosome 12q.

NIDDM has a substantial genetic component, but the nature of the genetic susceptibility is largely unknown. Maturity-onset diabetes of the young (MODY) is a genetically heterogeneous monogenic form of NIDDM characterized by an early age of onset and autosomal dominant inheritance, and linkage studies have identified genes that are mutated in different MODY pedigrees on chromosome 20 (MODY1 locus, hepatocyte nuclear factor-4alpha [HNF-4alpha] gene), chromosome 7 (MODY2 locus, glucokinase gene), and chromosome 12 (MODY3 locus, HNF-1alpha gene). We studied an extended pedigree in which multiple members are affected by late-onset NIDDM associated with insulin resistance and performed linkage analysis with four microsatellite markers in the MODY3 region of chromosome 12q. We found significant evidence for linkage between NIDDM and the MODY3 locus (logarithm of odds score 3.65 at theta = 0.008 telomeric to marker D12S321), but sequencing of the 10 exons and promoter of HNF-1alpha did not identify any causative mutation in this gene. Our results indicate that the region of chromosome 12q close to MODY3 harbors a novel susceptibility gene or genes for NIDDM.

Murine Wnt-11 and Wnt-12 have temporally and spatially restricted expression patterns during embryonic development.

The Wnt gene family encodes a set of signalling molecules implicated in the development of a wide range of organisms. We have recently cloned partial cDNA sequences of murine Wnt-11 and Wnt-12. Here, we describe the spatio-temporal expression patterns of both genes during mouse embryogenesis. Wnt-11 expression is first detected within the truncus arteriosus from 8.25 dpc. By 9.5 dpc, Wnt-11 expression is detected in the somites at the medial junction of the dermatome and the myotome. Wnt-11 transcripts are also detected in limb bud mesenchyme from the time the bud is first visible. Wnt-12 is detected in the apical ectodermal ridge from 10.5 dpc. The implications of these expression patterns are discussed.

De novo mutations of the Patched gene in nevoid basal cell carcinoma syndrome help to define the clinical phenotype.

The demonstration that mutations in the Patched (PTCH) gene cause nevoid basal cell carcinoma syndrome (NBCCS) has led to the identification of the exact molecular lesion in a percentage of individuals with the syndrome. In addition, it has been possible to determine, through molecular analysis of parents and other relatives of these individuals, if the mutation is inherited or has arisen de novo. We have previously reported 28 mutations in individuals with NBCCS, and here we present an additional 4 novel mutations. We have also analyzed relatives of a number of the individuals in whom we have found mutations. In total we have identified 8 individuals who carry a de novo mutation in the PTCH gene. In 5 of these cases, clinical and radiological examination had not unequivocally ruled out a diagnosis in one of the parents. This helps to define the clinical phenotype and suggests that diagnostic criteria in this complex syndrome may require review.

Prenatal diagnosis of cystic fibrosis by using linked DNA markers in 138 pregnancies at 1-in-4 risk.

Prenatal diagnosis was carried out in 138 pregnancies at 1-in-4 risk for cystic fibrosis (CF) by using closely linked DNA markers, including XV-2c and KM-19. In fully informative families, 25 of 123 (20%) fetuses were predicted to be affected; 16 of these 25 pregnancies were terminated and 9 were continued. Postnatal sweat tests are completed in 42 cases; the diagnoses were confirmed in 4 of 4 infants predicted to be affected and in 37 of 38 infants predicted to be unaffected. One infant predicted to be a carrier had an abnormal sweat test after birth, but the mother also had an abnormal sweat test, and there was no evidence of an error in linkage analysis. The data indicate that prenatal diagnosis using linkage analysis is fully informative in most families and is highly reliable with either chorionic villus sampling or amniocentesis. Although outcome data are available on only 42 pregnancies, based on our experience, on general principles of linkage analysis, and on the tight linkage of the known DNA markers with CF, we recommend that DNA analysis replace microvillar intestinal enzyme analysis for 1-in-4 risk pregnancies when DNA is available from the propositus.

Clinically relevant dermatology resources and the Internet: An introductory guide for practicing physicians.

The number of dermatology sites on the Internet is growing rapidly and the resources they offer are of great benefit to dermatologists and physicians. The mainstay of dermatologic diagnosis is that of visual inspection and gross morphology, therefore, the use of improved imaging techniques, which allow for the rapid collection, electronic transmission, and indexing of images aids in the accurate recognition and interpretation of skin lesions. The graphic nature of the field of dermatology kindly lends itself to the use of the Internet. The enhanced ability to access information,and share expert opinion worldwide will help lessen inappropriate treatment or delayed referral to an appropriate specialist and facilitate the accurate diagnosis of various dermatologic diseases. Concerns about the quality of data are examined and an evaluation scheme proposed. An overview of available resources is presented along with links to additional resources to aid the reader in the identification of additional sites to explore. Sites were selected with the goal of identifying those that provide a broad range of information worthwhile to the dermatologist and general practitioner. Resources including, but not limited to, image atlases, electronic texts, drug databases, case study archives, laboratory testing, and clinical procedures are examined.

Direct effects of Bmi1 on p53 protein stability inactivates oncoprotein stress responses in embryonal cancer precursor cells at tumor initiation.

Embryonal cancer can arise from postnatally persistent embryonal remnant or rest cells, which are uniquely characterized by the absence of p53 mutations. Perinatal overexpression of the MycN oncoprotein in embryonal cancer precursor cells causes postnatal rests, and later tumor formation through unknown mechanisms. However, overexpression of Myc in adult tissues normally activates apoptosis and/or senescence signals as an organismal defense mechanism against cancer. Here, we show that perinatal neuroblastoma precursor cells exhibited a transiently diminished p53 response to MycN oncoprotein stress and resistance to trophic factor withdrawal, compared with their adult counterpart cells from the TH-MYCN(+/+) transgenic mouse model of neuroblastoma. The adult stem cell maintenance factor and Polycomb group protein, Bmi1 (B-cell-specific Moloney murine leukemia virus integration site), had a critical role at neuroblastoma initiation in the model, by repressing p53 responses in precursor cells. We further show in neuroblastoma tumor cells that Bmi1 could directly bind p53 in a complex with other Polycomb complex proteins, Ring1A or Ring1B, leading to increased p53 ubiquitination and degradation. Repressed p53 signal responses were also seen in precursor cells for other embryonal cancer types, medulloblastoma and acute lymphoblastic leukemia. Collectively, these date indicate a general mechanism for p53 inactivation in some embryonal cell types and consequent susceptibility to MycN oncogenesis at the point of embryonal tumor initiation.