SKI Gene Research Articles

Analysis of phenotype and genetic variant in a family with Shprintzen-Goldberg syndrome

To explore the genetic basis for a proband with Shprintzen-Goldberg syndrome (SGS). Whole exome sequencing was carried out to detect potential variants associated with the relevant phenotypes. Candidate variants were verified by Sanger sequencing of the patient and her family. DNA sequencing revealed that that the proband has carried a de novo heterozygous missense c.94C>G (p.Leu32Val) variant in exon 1 of the SKI gene (NM_003036), which has been reported previously. The same variant was not detected in either parent. Based on the guidelines of the American College of Medical Genetics and Genomics, the variant was predicted to be pathogenic (PS1+PS2+PM1+PM2+PP2+PP3). The SKI c.94C>G (p. Leu32Val) variant probably underlay the autosomal dominant SGS in this patient.

Transcription Factor SP2 Regulates Ski-mediated Astrocyte Proliferation In Vitro

Transcription factors bind specific sequences upstream of the 5′ end of their target genes to ensure proper spatiotemporal expression of the target gene. This study aims to demonstrate that the transcription factor SP2 regulates expression of the Ski gene, which has specific binding sites for SP2, and thus enables Ski to regulate astrocyte proliferation. The upstream regulation mechanism of astrocyte proliferation was explored to further regulate the formation of glial scar in specific time and space after spinal cord injury. JASPAR and UCSC databases were used to predict transcription factor binding and the threshold was gradually reduced to screen transcription factors upstream of Ski, leading to the identification of SP2. Next, we analyzed the correlation between the expression of SP2 and Ski in normal astrocytes and reactive astrocytes, as well as the changes in astrocyte proliferation. To confirm that SP2 regulates Ski during astrocyte proliferation, astrocytes were transfected siRNA targeting SP2 and then astrocyte proliferation were analyzed. Finally, a dual luciferase reporter assay and Chromatin immunoprecipitation (ChIP) assay confirmed that the promoter region of Ski contained a specific SP2 binding site. This is the first that SP2 has been identified and confirmed to play an important role in astrocyte proliferation by regulating Ski expression. These results may help identify novel targets for the treatment of spinal cord injury.

Deviation of paradigmatic mutations found in shprintzen-goldberg syndrome

Shprintzen-Goldberg (S-G) Syndrome known as rare congenital connective tissue disorder where craniosynostosis and marfanoid habitus found to be the usual presentation. Craniofacial dysmorphism with multi-organ involvement documented to be amongst prominent features of this syndrome. Case characteristics is five-month-old male infant with craniosynostosis, and motor developmental delay was evaluated for congenital connective tissue disorder. Dysmorphic craniofacial features like dolichocephaly, triangular forehead, ocular hypertelorism, micrognathia and retrognathia were noticed besides congenital umbilical hernia, empty scrotal sac, clinodactyly with long slender fingers, hyper-mobile joints, hypotonia. Subsequent investigations revealed normal male karyotype (46, XY) while genetic analysis depicted missense mutations in six different genes. Conventionally, mutation in SKI gene reported for its’ associated with S-G syndrome where dysregulation of TGF-β signaling was discussed as the primary reason. In the present case discussed here, it was found to have polygenic mutational association where few novel genetic mutations were seen.

Shprintzen-Goldberg Syndrome: A Rare Disorder

The Shprintzen-Goldberg syndrome (SGS) or velo-cardio-facial syndrome (VCFS) is an extremely rare disorder of connective tissue with a characteristic facial dysmorphism, marfanoid features, craniosynostosis, dolichocephaly, cardiovascular anomalies and mild to moderate mental retardation. It may be a de novo gene mutation or inherited as an autosomal dominant disorder having SKI gene and Fibrillin-1 gene (FBN1) mutations, located on chromosome 15q21.1. We report a case of a 3-month, developmentally delayed male infant admitted to the hospital with syndromic facies, craniosynostosis, joint laxity and on echocardiography, aortic root dilatation. A probable diagnosis of SGS was made on the clinical grounds. We did not have the facility for genetic chromosomal analysis. He was discharged with family counselling and follow-up for future developmental rehabilitation.

A de novo mutation in DHD domain of SKI causing spina bifida with no craniofacial malformation or intellectual disability.

Shprintzen-Goldberg syndrome (SGS) is a rare systemic connective tissue disorder characterized by craniofacial, skeletal, and cardiovascular manifestations. It is associated with a significant risk of intellectual disability, a feature which distinguishes it from Marfan and Loeys-Dietz syndromes. SGS is mainly caused by mutations in the SKI gene, a repressor of TGF-β activity. Most SKI mutations are found in exon 1 of the gene and are located in the R-SMAD domain, a proposed hotspot for de novo mutations. Here, we report on a de novo SKI mutation located in the DHD domain of SKI. By adding our finding to previously reported de novo SKI mutations, a new mutational hotspot in the DHD domain is proposed. Our patient presented with a lipomeningomyelocele, tethered cord, and spina bifida but with no SGS-related clinical findings apart from a marfanoid habitus and long slender fingers. Specifically, she did not have an intellectual disability, craniofacial, or cardiovascular abnormalities. By comparing the clinical findings on patients with mutations in the R-SMAD and DHD domains of SKI, we propose that mutations in those domains have different effects on TGF-β activity during embryonic development with resulting phenotypic differences.

MYB induces the expression of the oncogenic corepressor SKI in acute myeloid leukemia.

Acute myeloid leukemia (AML) arises through clonal expansion of transformed myeloid progenitor cells. The SKI proto-oncogene is highly upregulated in different solid tumors and leukemic cells, but little is known about its transcriptional regulation during leukemogenesis. MYB is an important hematopoietic transcription factor involved in proliferation as well as differentiation and upregulated in most human acute leukemias. Here, we find that MYB protein binds within the regulatory region of the SKI gene in AML cells. Reporter gene assays using MYB binding sites present in the SKI gene locus show MYB-dependent transcriptional activation. SiRNA-mediated depletion of MYB in leukemic cell lines reveals that MYB is crucial for SKI gene expression. Consistently, we observed a positive correlation of MYB and SKI expression in leukemic cell lines and in samples of AML patients. Moreover, MYB and SKI both were downregulated by treatment with histone deacetylase inhibitors. Strikingly, differentiation of AML cells induced by depletion of MYB is attenuated by overexpression of SKI. Our findings identify SKI as a novel MYB target gene, relevant for the MYB-induced differentiation block in leukemic cells.

Identification of the Oncogene SKI As a New Target Gene of the Myeloid Transcription Factor c-MYB in AML

Background:Acute myeloid leukemia (AML) accounts for 80% of acute leukemias and arises through clonal expansion and arrest of differentiation of hematopoietic progenitor cells in the bone marrow. Depending on the AML subtype and age of the patient, AML patients have a 5-year survival rate of about 25%. AML is a genetically heterogenous disease, where chromosomal aberrations, point mutations in critical oncogenes as well as aberrant expression of key regulatory factors of hematopoiesis collude during transformation. c-MYB is an important hematopoietic transcription factor involved in proliferation and differentiation of progenitor cells of the myeloid and lymphoid lineages. It was first described as a viral oncogene of avian leukemia viruses and is upregulated or mutated in many leukemic subtypes as well as solid tumors. c-MYB interacts with other transcription factors or co-factors, which are essential for its transcriptional activity. In this regard, c-MYB transactivation ability is inhibited by a histone deacetylases recruiting corepressor complex containing SKI, TIF1BETA, NCOR and mSIN3A. c-SKI is a proto-oncogene and an inhibitor of TGFβ signalling. However, it acts not only as a transcriptional co-repressor but also as a transcriptional co-activator. Like c-MYB, c-SKI is upregulated in different solid tumors and leukemias. Though SKI activity is well described, transcriptional regulation of the SKI gene itself still remains unknown. Here, we deliver insight into the transcriptional regulation of the human SKI gene via the transcription factor c-MYB.Methods:In silico analyses were performed to identify potential MYB binding sites in the SKI regulatory region. Chromatin immunoprecipitation (ChIP) assays were used to validate the interaction between MYB and the potential SKI regulatory regions. Reporter gene assays were engaged to analyze MYB regulatory potential regarding SKI expression. RNAi experiments were performed to further examine transcriptional regulation of SKI by MYB. Since MYB is known to be downregulated by the histone deacetylase inhibitor (HDACi) valproic acid (VPA), MYB and SKI protein levels were analyzed in AML cell lines treated with VPA via Western Blot. Correlated protein levels of MYB and SKI were examined in the myeloid leukemia cell lines HL60, U937, THP1, NB4 and K562 as well as in primary cells of AML patients (n=27). Correlation of MYB and SKI transcript levels were performed in three different data sets of primary AML samples. The first cohort (n=7) was analyzed via RT-qPCR. Cohort 2 consists of cDNA microarray data of AML patients (n=17). Furthermore, principal component analysis (PCA) of the gene expression profile of MYB and SKI of AML patients (n=542) were performed with the leukemia gene atlas (LGA).Results:In silico analyses revealed four putative MYB binding sites (MBS1-4) in the SKI regulatory region. Direct binding of MYB to the regulatory sites MBS2-4 of the SKI gene could be confirmed via ChIP experiments. Dual luciferase reporter gene assays comprising c-MYB binding sites present in the SKI gene locus further show c-MYB-dependent transcriptional activation of the reporter. RNAi experiments depleting c-MYB in leukemic cell lines resulted in the decrease of SKI protein levels and thereby reveal that c-MYB is essential for the induction of SKI gene expression. Accordingly, treatment of the AML cell lines with the HDACi VPA led to a decrease of MYB and consequently SKI protein levels. Consistently, we observed a positive correlation of MYB and SKI protein expression in leukemic cell lines and in samples of AML patients. Moreover, a highly positive correlation of MYB and SKI transcript levels could be observed in three different cohorts of AML patients, further confirming regulation of SKI expression by the transcription factor MYB.Conclusion:Our findings provide new insights in the transcriptional regulation of the proto-oncogene c-SKI by the oncogenic transcription factor c-MYB during leukemogenesis. c-MYB and c-SKI expression and functions are highly positively correlated in human AML suggesting that c-SKI is a mediator of c-MYB oncogenic potential. So far, various therapeutic approaches targeting MYB failed to be transferred to patients. In this regard, c-MYB and c-SKI represent promising marker and target proteins for novel HDACi-based therapeutic approaches in AML. DisclosuresNo relevant conflicts of interest to declare.

Comparative evaluation of the wound-healing potency of recombinant bFGF and ski gene therapy in rats

We previously demonstrated that cellular Sloan-Kettering Institute (c-Ski) played a dual role, both promoting wound healing and alleviating scar formation. However, its mechanism and therapeutic effects are not clear, especially compared with widely used treatments, such as basic fibroblast growth factor (bFGF) administration. However, Ski treatment led to an even shorter healing time and a more significant reduction in scar area than bFGF treatment. The mechanism underlying this difference was related to a reduced inflammatory response, more rapid re-epithelialization, less collagen after healing and a greater reduction in the proportion of alpha-smooth muscle actin and SMemb-positive cells after Ski treatment. These results not only confirm that Ski plays a dual role in promoting healing and reducing scarring but also suggest that Ski yields better treatment effects than bFGF, indicating better potential therapeutic effects in wound repair.

RETRACTED: Ski diminishes TGF-β1-induced myofibroblast phenotype via up-regulating Meox2 expression

The aim of the present work was to investigate the mechanism of transforming growth factor (TGF)-β1 and Sloan-Kettering Institute (Ski) in the pathogenesis of hypertrophic scars (HS). Wound healing is an inherent process, but the aberrant wound healing of skin injury may lead to HS. There has been growing evidence suggesting a role for TGF-β1 and Ski in the pathogenesis of fibrosis. The MTT assay was used to detect the cell proliferation induced by TGF-β1. The Ski gene was transduced into cells with an adenovirus, and then the function of Ski in cell proliferation and differentiation was observed. Ski mRNA levels were measured by RT-PCR. Western blotting was used to detect the protein expression of α-SMA, E-cadherin, Meox1, Meox2, Zeb1 and Zeb2. TGF-β1 can promote human skin fibroblast (HSF) cell proliferation in a time-dependent manner, but the promoting effect could be suppressed by Ski. TGF-β1 also induces the formation of the myofibroblast phenotype and the effect of TGF-β1 could be diminished by Ski. Also, Ski modulates the cardiac myofibroblast phenotype and function through suppression of Zeb2 by up-regulating the expression of Meox2. Ski diminishes the myofibroblast phenotype induced by TGF-β1 through the suppression of Zeb2 by up-regulating the expression of Meox2.

Epigenome-wide DNA methylation assay reveals placental epigenetic markers for noninvasive fetal single-nucleotide polymorphism genotyping in maternal plasma.

The use of DNA methylation difference between maternal blood cell and fetal (placental) DNA is one of the main areas of interest for the development of fetal epigenetics markers in maternal plasma. We employed a methylation array (HumanMethylation450 array, Illumina, Inc.) to identify novel biomarkers that are specially hypermethylated in placental DNA versus maternal blood cells in a genome-wide basis. Validation by bisulfite genomic sequencing was performed and the priority was given to potential targets that harbor differential methylated CpG sites overlapped with at least two methylation-sensitive restriction enzyme (MSRE) recognizing sites, as well as one polymorphic single-nucleotide polymorphism (SNP), within a short DNA stretch. Three candidate regions of PSMB8, SKI, and CHST11 gene were selected for developing a preliminary polymerase chain reaction assay with MSRE digestion of maternal plasma DNA. SNP genotypes were confirmed by direct sequencing. We identified 2944 and 5218 fetal-specific hypermethylated CpG sites in the first- and third-trimester placenta, respectively, of which 2613 were overlapped, suggesting a consistency of differential methylation during the whole pregnancy. The array results were confirmed by bisulfite genomic sequencing. The preliminary tests in maternal plasma showed that postdigestion hypermathylated versions of these candidate molecules were detectable only in pregnant women. We further revealed that methylated targets in maternal plasma possessed the fetal SNP genotypes. The present studies systematically identified hypermethylated sites in fetal tissues and preliminarily demonstrated that some of the fetal epigenetic markers that contain informative SNPs have great potential for noninvasive fetal genetic diagnosis.

The SMAD-binding domain of SKI: a hotspot for de novo mutations causing Shprintzen-Goldberg syndrome.

Shprintzen-Goldberg syndrome (SGS) is a rare, systemic connective tissue disorder characterized by craniofacial, skeletal, and cardiovascular manifestations that show a significant overlap with the features observed in the Marfan (MFS) and Loeys-Dietz syndrome (LDS). A distinguishing observation in SGS patients is the presence of intellectual disability, although not all patients in this series present this finding. Recently, SGS was shown to be due to mutations in the SKI gene, encoding the oncoprotein SKI, a repressor of TGFβ activity. Here, we report eight recurrent and three novel SKI mutations in eleven SGS patients. All were heterozygous missense mutations located in the R-SMAD binding domain, except for one novel in-frame deletion affecting the DHD domain. Adding our new findings to the existing data clearly reveals a mutational hotspot, with 73% (24 out of 33) of the hitherto described unrelated patients having mutations in a stretch of five SKI residues (from p.(Ser31) to p.(Pro35)). This implicates that the initial molecular testing could be focused on mutation analysis of the first half of exon 1 of SKI. As the majority of the known mutations are located in the R-SMAD binding domain of SKI, our study further emphasizes the importance of TGFβ signaling in the pathogenesis of SGS.

EvaluatingSKIas a candidate gene for non‐syndromic cleft lip with or without cleft palate

Non-syndromic cleft lip with or without cleft palate (NSCL/P) is one of the most common of all congenital malformations and has a multifactorial etiology. Findings in mice suggest that the v-ski sarcoma viral oncogene homolog (SKI) gene is a candidate gene for orofacial clefting. In humans, a significant association between rs2843159 within SKI and NSCL/P has been reported in patients from the Philippines and South America. In the South American patients, the association was driven by the subgroup of patients with non-syndromic cleft lip only (NSCLO). Here we investigated the association with rs2843159 in a Mayan Mesoamerican population (172 NSCL/P patients and 366 controls). In addition, we analyzed the phenotypic subgroups NSCLO and non-syndromic cleft of lip and palate (NSCLP). A trend towards association between rs2843159 and NSCL/P was observed in the Mayan cohort (P = 0.097), and we found a stronger association in the NSCLP subgroup (P = 0.072) despite a limited sample size. To investigate whether other common variants within the SKI gene contribute to NSCL/P susceptibility in European and Asian populations, we also analyzed genotypic data from two recent genome-wide association studies using set-based statistical approaches. These analyses detected a trend toward association in the European population. Our data provide limited support for the hypothesis that common SKI variants are susceptibility factors for NSCL/P.

Upregulation of Ski in Fibroblast is Implicated in the Peroxisome Proliferator- Activated Receptor δ-Mediated Wound Healing

Background/Aim: Both peroxisome proliferator-activated receptor (PPAR) δ and Ski are investigate the interaction of PPARδ and Ski and this interaction-associated effect in wound healing. Methods: Effect of PPARδ activation on Ski expression was detected in rat skin fibroblasts by real-time PCR and western blot. Luciferase assay, electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP) assay were performed to identify the binding site of PPARδ in the promoter region of rat Ski gene. And the functional activity of PPARδ regulation to Ski was detected in fibroblast proliferation and rat skin wound healing model. Results: PPARδ agonist GW501516 upregulated Ski expression in a dose-dependent manner. Direct repeat-1 (DR1) response element locating at -865∼-853 in Ski promoter region was identified to mediate PPARδ binding to Ski and associated induction of Ski. Furthermore, PPARδ upregulated Ski to promote fibroblasts proliferation and rat skin wound repair, which could be largely blocked by pre-treated with Ski RNA interference. Conclusion: This study demonstrates that Ski is a novel target gene for PPARδ and upregulation of Ski to promote fibroblast proliferation is implicated in the PPARδ-mediated wound healing.

MicroRNA‐155 targets the SKI gene in human melanoma cell lines

The SKI protein is a transcriptional coregulator over-expressed in melanoma. Experimentally induced down-regulation of SKI inhibits melanoma cell growth in vitro and in vivo. MicroRNAs (miRNAs) negatively modulate gene expression and have been implicated in oncogenesis. We previously showed that microRNA-155 (miR-155) is down-regulated in melanoma cells as compared with normal melanocytes and that its ectopic expression impairs proliferation and induces apoptosis. Here, we investigated whether miR-155 could mediate melanoma growth inhibition via SKI gene silencing. Luciferase reporter assays demonstrated that miR-155 interacted with SKI 3'UTR and impaired gene expression. Transfection of melanoma cells with miR-155 reduced SKI levels, while inhibition of endogenous miR-155 up-regulated SKI expression. Specifically designed small interfering RNAs reduced SKI expression and inhibited proliferation. However, melanoma cells over-expressing a 3'UTR-deleted SKI were still susceptible to the antiproliferative effect of miR-155. Our data demonstrate for the first time that SKI is a target of miR-155 in melanoma. However, impairment of SKI expression is not the leading mechanism involved in the growth-suppressive effect of miR-155 found in this malignancy.

Ski, a modulator of wound healing and scar formation in the rat skin and rabbit ear

We recently demonstrated that Ski is a novel wound healing-related factor that promotes fibroblast proliferation and inhibits collagen secretion. Here, we show that increasing local Ski expression by gene transfer not only significantly accelerated wound healing by relieving inflammation, accelerating re-epithelialization and increasing formation of granulation tissue, but also reduced scar formation by decreasing collagen production in rat dermal wounds. Similarly, ski gene transfer accelerated wound healing, reduced the protuberant height and volume of scars and increased collagen maturity in a hypertrophic scar model in the rabbit ear. Conversely, reducing Ski expression in the wound by RNA interference resulted in significantly slower wound healing and increased scar area in rat dermal wounds. We demonstrated that these effects of Ski are associated with transforming growth factor-β-mediated signalling pathways through both Smad2/3-dependent and Smad-independent pathways. Together, our results define a dual role for Ski in promoting wound healing and alleviating scar formation, identifying a new target for therapeutic approaches to preventing scar hyperplasia and accelerating wound healing.

The Ski proto-oncogene regulates body composition and suppresses lipogenesis

The Ski gene regulates skeletal muscle differentiation in vitro and and in vivo. In the c-Ski overexpression mouse model there occurs marked skeletal muscle hypertrophy with decreased adipose tissue mass. In this study, we have investigated the underlying molecular mechanisms responsible for the increased skeletal muscle and decreased adipose tissue mass in the c-Ski mouse. Growth and body composition analysis (tissue weights and dual energy X-ray absorptiometry) coupled with skeletal muscle and white adipose gene expression and metabolic phenotyping in c-Ski mice and wild-type (WT) littermate controls was performed. The growth and body composition studies confirmed the early onset of accelerated body growth, with increased lean mass and decreased fat mass in the c-Ski mice. Gene expression analysis in skeletal muscle from c-Ski mice compared with WT mice showed significant differences in myogenic and lipogenic gene expressions that are consistent with the body composition phenotype. Skeletal muscle of c-Ski mice had significantly repressed Smad1, 4, 7 and myostatin gene expression and elevated myogenin, myocyte enhancer factor 2, insulin-like growth factor-1 receptor and insulin-like growth factor-2 expression. Strikingly, expression of the mRNAs encoding the master lipogenic regulators, sterol-regulatory enhancer binding protein 1c (SREBP1c), and the nuclear receptor liver X-receptor-alpha, and their downstream target genes, SCD-1 and FAS, were suppressed in skeletal muscle of c-Ski mice, as were the expressions of other nuclear receptors involved in adipogenesis and metabolism, such as peroxisome proliferator-activated receptor-gamma, glucocorticoid receptor and retinoic acid receptor-related orphan receptor-alpha. Transfection analysis demonstrated Ski repressed the SREBP1c promoter. Moreover, palmitate oxidation and oxidative enzyme activity was increased in skeletal muscle of c-Ski mice. These results suggest that the Ski phenotype involves attenuated lipogenesis, decreased myostatin signalling, coupled to increased myogenesis and fatty acid oxidation. Ski regulates several genetic programs and signalling pathways that regulate skeletal muscle and adipose mass to influence body composition development, suggesting that Ski may have a role in risk for obesity and metabolic disease.

Effect of ski-siRNA on biological function of human hepatoma cell line HepG2

Objective:To design and prepare siRNAs targeting ski gene and to observe its influence on the biological functions of HepG2 cells,such as proliferation,cell cycle,apoptosis,etc..Methods: Three specific siRNAs of ski were designed and synthesized,and were transiently transfected into HepG2 via cathodolyte liposome transfection method.Real-time PCR and Western blotting were used to measure ski expression at mRNA and protein levels.The cell proliferation was assessed by MTT assay and the changes in cell cycle and apoptosis were evaluated by flow cytometry.Results: All the 3 specific ski-siRNA(A,B,C) effectively inhibited the expression of ski gene,with ski-siRNA-B having the highest inhibition rate(70%).Furthermore,the ski expression had a decreasing tendency with the transfection time.The proliferation of HepG2 cells was markedly inhibited by ski-siRNAs(P0.05); the number of cells at S stage was obviously decreased,being 2 folds that of the negative control group.Conclusion: The siRNA of ski gene can effectively induce growth inhibition of HepG2 cells and reduce cells of S stage, which is possibly through down-regulation of ski gene.

Genetic variation in the proto-oncogene SKI and risk for orofacial clefting

Background SKI is a proto-oncogene that is required for development of the central nervous system and skeletal muscle, and is involved in specifying selected cranial neural-crest-derived craniofacial structures. To identify genetic variants within the SKI gene and investigate the potential association between SKI polymorphisms and risk for orofacial defects, we initially re-sequenced the gene. Methods DNA re-sequencing of all seven exons of the SKI gene was performed on 100 control samples. Subsequently, we genotyped 394 samples (148 CLP cases, 99 CP cases, and 147 control infants) for a novel SNP identified in the DNA re-sequencing effort using restriction fragment length polymorphism (RFLP) analysis. Results We identified one polymorphism in exon 1 of the SKI gene (257C > G) from controls. This SNP resulted in an amino acid change from alanine to glycine (A62G, GenBank Accession No. NM_003036). Among all samples genotyped by the RFLP method, variants (CG, GG) were found in 10.5% of the cases, compared to a prevalence of 17.7% in the controls. The odds ratio was calculated to be 0.6, with a 95% confidence interval (CI) of 0.3–1.0. Conclusion In a population of California infants with craniofacial defects, a novel polymorphism of the SKI gene was found to be associated with a decreased risk for orofacial defects. The function of this polymorphism and how it might confer protection to the embryo against craniofacial malformations is currently under investigation in our laboratory.

Palmitoylation is required for the production of a soluble multimeric Hedgehog protein complex and long-range signaling in vertebrates.

Hedgehog (Hh) signaling plays a major role in multiple aspects of embryonic development. A key issue in Hh signaling is to elucidate the molecular mechanism by which a Hh protein morphogen gradient is formed despite its membrane association. In this study, we used a combination of genetic, cellular, and biochemical approaches to address the role of lipid modifications in long-range vertebrate Hh signaling. Our molecular analysis of knockout mice deficient in Skn, the murine homolog of the Drosophila ski gene, which catalyzes Hh palmitoylation, and gene-targeted mice producing a nonpalmitoylated form of Shh indicates that Hh palmitoylation is essential for its activity as well as the generation of a protein gradient in the developing embryos. Furthermore, our biochemical data show that Hh lipid modifications are required for producing a soluble multimeric protein complex, which constitutes the major active component for Hh signaling. These results suggest that soluble Hh multimeric complex travels in the morphogenetic field to activate Hh signaling in distant Hh-responsive cells.

A girl with 1p36 deletion syndrome and congenital fiber type disproportion myopathy

Chromosome 1p36 deletion syndrome is characterized by hypotonia, moderate to severe developmental and growth retardation, and characteristic craniofacial dysmorphism. Muscle hypotonia and delayed motor development are almost constant features of the syndrome. We report a 4-year-old Japanese girl with 1p36 deletion syndrome whose muscle pathology showed congenital fiber type disproportion (CFTD) myopathy. This is the first case report of 1p36 deletion associated with CFTD. This association may indicate that one of the CFTD loci is located at 1p36. Ski proto-oncogene -/- mice have phenotypes that resemble some of the features observed in patients with 1p36 deletion syndrome. Because fluorescent in situ hybridization analysis revealed that the human SKI gene is deleted in our patient, some genes in 1p36, including SKI proto-oncogene, may be involved in muscle hypotonia and delayed motor development in this syndrome.