Trisomy 9p with i(9p) and t(9q18p)

Summary The trisomy 9p syndrome in a 2-year-old girl with moderate mental retardation is presented. She has a unique karyotype with a de novo isochromosome 9p and a translocation between 9q and 18p.     

Structural Characterization of Bardet-Biedl Syndrome 9 Protein (BBS9)

The Bardet-Biedl syndrome protein complex (BBSome) is an octameric complex that transports membrane proteins into the primary cilium signaling organelle in eukaryotes and is implicated in human disease. Here we have analyzed the 99-kDa human BBS9 protein, one of the eight BBSome components. The protein is composed of four structured domains, including a β-stranded N-terminal domain. The 1.8 Å crystal structure of the 46-kDa N-terminal domain reveals a seven-bladed β-propeller. A structure-based homology search suggests that it functions in protein-protein interactions. We show that the Bardet-Biedl syndrome-causing G141R mutation in BBS9 likely results in misfolding of the β-propeller. Although the C-terminal half of BBS9 dimerizes in solution, the N-terminal domain only does so in the crystal lattice. This C-terminal dimerization interface might be important for the assembly of the BBSome.     

Identification and analysis of the dog keratin 9 (KRT9) gene

We have identified the gene coding for the canine ortholog of the human keratin 9 protein using the inverse-polymerase chain reaction (PCR) strategy. Sequence comparison and structure analysis of the gene show marked similarity with the human gene. This gene spans about 7 kb and spreads over eight exons. In the dog gene, the reading frame is extended by 20 codons, the first in-frame stop codon being in exon 8 in the dog rather than in exon 7 as in humans. Alignment of human and dog predicted amino acid sequences confirms the high analogy, reaching 75% identity and 95% similarity in the rod domain. Interestingly, the glycine-loop motif number in the C-terminal V2 variable subdomain of the protein increases from 19 in human to 43 in dog, generating a size difference of 12 kDa between the two proteins. Due to its restricted expression pattern in mammalian epidermis, dog keratin 9 gene was a good candidate gene for the genetic palmoplantar hyperkeratosis observed in the Dogue de Bordeaux. However, no polymorphism associated with the pathology was detected within an affected Dogue de Bordeaux pedigree ruling out this hypothesis.     

Regulation of Bone Morphogenetic Protein 9 (BMP9) by Redox-dependent Proteolysis

BMP9, a member of the TGFβ superfamily, is a homodimer that forms a signaling complex with two type I and two type II receptors. Signaling through high-affinity activin receptor-like kinase 1 (ALK1) in endothelial cells, circulating BMP9 acts as a vascular quiescence factor, maintaining endothelial homeostasis. BMP9 is also the most potent BMP for inducing osteogenic signaling in mesenchymal stem cells in vitro and promoting bone formation in vivo. This activity requires ALK1, the lower affinity type I receptor ALK2, and higher concentrations of BMP9. In adults, BMP9 is constitutively expressed in hepatocytes and secreted into the circulation. Optimum concentrations of BMP9 are essential to maintain the highly specific endothelial-protective function. Factors regulating BMP9 stability and activity remain unknown. Here, we showed by chromatography and a 1.9 Å crystal structure that stable BMP9 dimers could form either with (D-form) or without (M-form) an intermolecular disulfide bond. Although both forms of BMP9 were capable of binding to the prodomain and ALK1, the M-form demonstrated less sustained induction of Smad1/5/8 phosphorylation. The two forms could be converted into each other by changing the redox potential, and this redox switch caused a major alteration in BMP9 stability. The M-form displayed greater susceptibility to redox-dependent cleavage by proteases present in serum. This study provides a mechanism for the regulation of circulating BMP9 concentrations and may provide new rationales for approaches to modify BMP9 levels for therapeutic purposes.     

Contents of Volume 9 (2001)

Volume Contents

Contents of Volume 9 (2001)     

Content Volume 9 (2000)

Volume Contents

Content Volume 9 (2000)     

Changes in retinal aquaporin-9 (AQP9) expression in glaucoma

The eye contains numerous water channel proteins and the roles of AQPs (aquaporins) in the retina are blurred, especially under disease conditions. The purpose of this study was to investigate the expression of AQP9 gene and proteins affected by elevated IOP (intraocular pressure) in a rat model of glaucoma induced by intravitreous injection of hypertonic saline into the episcleral veins. The gene and protein expressions of AQP9 were investigated by real-time PCR and Western blotting. The immunoreactive expression of AQP9, AQP4 and GFAP (glial fibrillary acidic protein) in the optic nerve of rats exposed to experimentally elevated IOP was detected by immunofluorescence microscopy. The mRNA and protein expression levels of AQP9 were up-regulated in the retina of an animal model of glaucoma. The immunoreactivities of the AQP9, AQP4 and GFAP were also detected and increased in the optic nerve region. The expression of AQP9 was up-regulated in this glaucoma model and the immunoreactivities of the AQP4 and GFAP were also detected as co-localizing with AQP9 in the optic nerve region, indicating retina ganglion cells were surrounded by activated astrocytes. This may indicate that the injured neurons may rely on the astrocytes. The alterations of AQP expression may compensate the glaucomatous damage.     

Histone deacetylase 9 (HDAC9) regulates the functions of the ATDC (TRIM29) protein

Histone deacetylase 9 (HDAC9), like most Class II HDACs, catalyzes the removal of acetyl moieties from the ε-amino groups of conserved lysine residues in the N-terminal tail of histones. Biologically, HDAC9 regulates a wide variety of normal and abnormal physiological functions, including cardiac growth, T-regulatory cell function, neuronal disorders, muscle differentiation, development, and cancer. In a biochemical approach to identify non-histone substrates of HDAC9, we found that HDAC9 co-purifies specifically with the ataxia telangiectasia group D-complementing (ATDC; also called TRIM29) protein. HDAC9 deacetylates ATDC, alters the ability of ATDC to associate with p53, and consequently inhibits the cell proliferation-promoting activity of ATDC. These results implicate the importance of non-histone deacetylation by HDAC9 and confirm and further extend the multifunctions of this Class II deacetylase.     

Epigenetic and pharmacological control of pigmentation via Bromodomain Protein 9 (BRD9)

Lineage-specific differentiation programs are activated by epigenetic changes in chromatin structure. Melanin-producing melanocytes maintain a gene expression program ensuring appropriate enzymatic conversion of metabolites into the pigment, melanin, and transfer to surrounding cells. During neuroectodermal development, SMARCA4 (BRG1), the catalytic subunit of SWItch/Sucrose Non-Fermentable (SWI/SNF) chromatin remodeling complexes, is essential for lineage specification. SMARCA4 is also required for development of multipotent neural crest precursors into melanoblasts, which differentiate into pigment-producing melanocytes. In addition to the catalytic domain, SMARCA4 and several SWI/SNF subunits contain bromodomains which are amenable to pharmacological inhibition. We investigated the effects of pharmacological inhibitors of SWI/SNF bromodomains on melanocyte differentiation. Strikingly, treatment of murine melanoblasts and human neonatal epidermal melanocytes with selected bromodomain inhibitors abrogated melanin synthesis and visible pigmentation. Using functional genomics, iBRD9, a small molecule selective for the bromodomain of BRD9 was found to repress pigmentation-specific gene expression. Depletion of BRD9 confirmed a requirement for expression of pigmentation genes in the differentiation program from melanoblasts into pigmented melanocytes and in melanoma cells. Chromatin immunoprecipitation assays showed that iBRD9 disrupts the occupancy of BRD9 and the catalytic subunit SMARCA4 at melanocyte-specific loci. These data indicate that BRD9 promotes melanocyte pigmentation whereas pharmacological inhibition of BRD9 is repressive.     

Selective modulation of matrix metalloproteinase 9 (MMP-9) functions via exosite inhibition

Unregulated activities of the matrix metalloproteinase (MMP) family have been implicated in primary and metastatic tumor growth, angiogenesis, and pathological degradation of extracellular matrix components, such as collagen and laminin. However, clinical trials with small molecule MMP inhibitors have been largely unsuccessful, with a lack of selectivity considered particularly problematic. Enhanced selectivity could be achieved by taking advantage of differences in substrate secondary binding sites (exosites) within the MMP family. In this study, triple-helical substrates and triple-helical transition state analog inhibitors have been utilized to dissect the roles of potential exosites in MMP-9 collagenolytic behavior. Substrate and inhibitor sequences were based on either the alpha1(V)436-450 collagen region, which is hydrolyzed at the Gly (downward arrow) Val bond selectively by MMP-2 and MMP-9, or the Gly (downward arrow) Leu cleavage site within the consensus interstitial collagen sequence alpha1(I-III)769-783, which is hydrolyzed by MMP-1, MMP-2, MMP-8, MMP-9, MMP-13, and MT1-MMP. Exosites within the MMP-9 fibronectin II inserts were found to be critical for interactions with type V collagen model substrates and inhibitors and to participate in interactions with an interstitial (types I-III) collagen model inhibitor. A triple-helical peptide incorporating a fibronectin II insert-binding sequence was constructed and found to selectively inhibit MMP-9 type V collagen-based activities compared with interstitial collagen-based activities. This represents the first example of differential inhibition of collagenolytic activities and was achieved via an exosite-binding triple-helical peptide.     

Molecular characterization of a tandem-repeat galectin-9 (RuGlec9) from Korean rose bitterling (Rhodeus uyekii)

Galectin-9 is a b-galactoside-binding lectin that regulates many cellular functions, ranging from cell adhesion to pathogen recognition. We isolated and characterized the cDNA of tandem-repeat galectin-9 (RuGlec9) from the Korean rose bitterling (Rhodeus uyekii), an endemic Korean fish belonging to the Acheilognathinae subfamily of the Cyprinidae family. RuGlec9 cDNA is 1486 bp long and encodes a polypeptide of 323 amino acids containing two carbohydrate-recognition domains connected by a linker peptide. The deduced amino acid sequence of RuGlec9 shows 45-84% amino acid sequence identity to other galectin-9 sequences, including those from mammals and fish. RuGlec9 appeared in a large cluster with other galectin-9 sequences from fish and is more closely related to galectin-9 from Danio rerio than to those of other fish and mammals. RuGlec9 mRNA was expressed highly in the testis, spleen, intestine, stomach, and liver, and moderately in the brain, kidney, ovary, and gills of normal Korean rose bitterling. RuGlec9 mRNA expression in the spleen was increased by lipopolysaccharide. These results suggest that RuGlec9 plays a role in innate immunity in Korean rose bitterling.     

大熊猫生长分化因子9(GDF-9)基因克隆与序列分析

生长分化因子9(GDF-9)是转化生长因子β(TGF-β)超家族的一个新成员,主要表达于卵母细胞,调节卵泡早期发育. 本文以大熊猫基因组DNA为模板,克隆了大熊猫GDF-9基因.序列分析显示:大熊猫GDF-9基因含两个外显子,编码一个由453个氨基酸组成的蛋白前体.该结果为进一步分析大熊猫GDF-9基因生物学功能奠定了基础.     

Chiral resolutions of (9-anthryl)methoxyacetic acid and (9-anthryl)hydroxyacetic acid by capillary electrophoresis

The resolutions of (9-anthryl)methoxyacetic acid (9AMAA) and (9-anthryl)hydroxyacetic acid (9AHAA) were performed by capillary electrophoresis using hydroxypropyl-beta-cyclodextrin (HP-beta-CD) as a chiral selector. Various factors affecting migration time and resolutions of these compounds were investigated with a run voltage of 20 kV, column temperature 20 degrees C and 20 mM Tris-H(3)PO(4) buffer (pH 6.5) containing 5 mM HP-beta-CD for 9AMAA, or 10 mM HP-beta-CD for 9AHAA, (+/-)-9AMAA and (+/-)-9AHAA were successfully separated at Rs 3.27 and 1.92, respectively.     

Partial tetrasomy 9(9pter to 9q2101) due to an extra iso-dicentric chromosome.

A 3-year-old boy with partial No. 9 tetrasomy is described. The patient showed markedly retarded physical and mental development as well as multiple congenital anomalies. Routine chromosome analysis revealed an extra C-group chromosome. It had a pronounced secondary constriction at the proximal part of its long arm. Based on studies by a variety of banding techniques, the extra chromosome was identified to be an iso-dicentric No. 9 chromosome with inactivation of one of the two centromeres, the karyotype being 47,XY, + DIC (9)(Q2101). The value of BrdUrd treatment was emphasized in the detection of a very small piece of euchromatin within a long stretch of constitutive heterochromatin.     

Ubiquitin-specific peptidase 9, X-linked (USP9X) modulates activity of mammalian target of rapamycin (mTOR)

The mammalian target of rapamycin (mTOR) is an atypical serine/threonine kinase that responds to extracellular environment to regulate a number of cellular processes. These include cell growth, proliferation, and differentiation. Although both kinase-dependent and -independent functions of mTOR are known to be critical modulators of muscle cell differentiation and regeneration, the signaling mechanisms regulating mTOR activity during differentiation are still unclear. In this study we identify a novel mTOR interacting protein, the ubiquitin-specific protease USP9X, which acts as a negative regulator of mTOR activity and muscle differentiation. USP9X can co-immunoprecipitate mTOR with both Raptor and Rictor, components of mTOR complexes 1 and 2 (mTORC1 and -2), respectively, suggesting that it is present in both mTOR complexes. Knockdown of USP9X leads to increased mTORC1 activity in response to growth factor stimulation. Interestingly, upon initiation of differentiation of C2C12 mouse skeletal myoblasts, knockdown of USP9X increases mTORC2 activity. This increase in mTORC2 activity is accompanied by accelerated differentiation of myoblasts into myotubes. Taken together, our data describe the identification of the deubiquitinase USP9X as a novel mTORC1 and -2 binding partner that negatively regulates mTOR activity and skeletal muscle differentiation.     

Impact of pericentric inversion of Chromosome 9 [inv (9) (p11q12)] on infertility

BACKGROUND:

One of the frequent occurrences in chromosome rearrangements is pericentric inversion of the Chromosome 9; inv (9) (p11q12), which is consider to be the variant of normal karyotype. Although it seems not to correlate with abnormal phenotypes, there have been many controversial reports indicating that it may lead to abnormal clinical conditions such as infertility. The incidence is found to be about 1.98% in the general population.

MATERIALS AND METHODS:

We investigated the karyotypes of 300 infertile couples (600 individuals) being referred to our infertility clinic using standard GTG banding for karyotype preparation.

RESULTS:

The chromosomal analysis revealed a total of 15 (2.5%) inversions, among these, 14 male patients were inversion 9 carriers (4.69%) while one female patient was affected (0.33%). The incidence of inversion 9 in male patients is significantly higher than that of normal population and even than that of female patients (P< 0.05).

CONCLUSIONS:

This result suggests that inversion 9 may often cause infertility in men due to spermatogenic disturbances, which are arisen by the loops or acentric fragments formed in meiosis.