The recurrent homozygous translation start site variant in CCDC134 in an individual with severe osteogenesis imperfecta of non‐Morrocan ancestry

Taccyanna M. Ali ◽  
Bianca D. W. Linnenkamp ◽  
Guilherme L. Yamamoto ◽  
Rachel S. Honjo ◽  
Hamilton Cabral de Menezes Filho ◽  
2009 ◽  
Vol 151 (2) ◽  
pp. 193 ◽  
D. Calva ◽  
S. Chinnathambi ◽  
J.R. Howe

2021 ◽  
Vol 12 ◽  
Christian Otten ◽  
Tanja Seifert ◽  
Jens Hausner ◽  
Daniela Büttner

Pathogenicity of the Gram-negative bacterium Xanthomonas campestris pv. vesicatoria depends on a type III secretion (T3S) system which translocates effector proteins into plant cells. T3S systems are conserved in plant- and animal-pathogenic bacteria and consist of at least nine structural core components, which are designated Sct (secretion and cellular translocation) in animal-pathogenic bacteria. Sct proteins are involved in the assembly of the membrane-spanning secretion apparatus which is associated with an extracellular needle structure and a cytoplasmic sorting platform. Components of the sorting platform include the ATPase SctN, its regulator SctL, and pod-like structures at the periphery of the sorting platform consisting of SctQ proteins. Members of the SctQ family form a complex with the C-terminal protein domain, SctQC, which is translated as separate protein and likely acts either as a structural component of the sorting platform or as a chaperone for SctQ. The sorting platform has been intensively studied in animal-pathogenic bacteria but has not yet been visualized in plant pathogens. We previously showed that the SctQ homolog HrcQ from X. campestris pv. vesicatoria assembles into complexes which associate with the T3S system and interact with components of the ATPase complex. Here, we report the presence of an internal alternative translation start site in hrcQ leading to the separate synthesis of the C-terminal protein region (HrcQC). The analysis of genomic hrcQ mutants showed that HrcQC is essential for pathogenicity and T3S. Increased expression levels of hrcQ or the T3S genes, however, compensated the lack of HrcQC. Interaction studies and protein analyses suggest that HrcQC forms a complex with HrcQ and promotes HrcQ stability. Furthermore, HrcQC colocalizes with HrcQ as was shown by fluorescence microscopy, suggesting that it is part of the predicted cytoplasmic sorting platform. In agreement with this finding, HrcQC interacts with the inner membrane ring protein HrcD and the SctK-like linker protein HrpB4 which contributes to the docking of the HrcQ complex to the membrane-spanning T3S apparatus. Taken together, our data suggest that HrcQC acts as a chaperone for HrcQ and as a structural component of the predicted sorting platform.

1984 ◽  
Vol 3 (6) ◽  
pp. 403-406 ◽  
Mark Bloom ◽  
Nathan Brot ◽  
Bennett N. Cohen ◽  
Herbert Weissbach

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 3302-3302
Xining Yang ◽  
Ping Xiang ◽  
Leo Escano ◽  
Ishpreet Dhillon ◽  
Edith Schneider ◽  

Abstract Myeloid ecotropic virus insertion site 1 (MEIS1) is essential for normal hematopoiesis and is deregulated in a large subset of acute myeloid leukemia (AML) by yet unknown mechanisms. We previously identified 3 candidate enhancer regions: enhancer region 1 (E1) at -2 kb upstream; enhancer region 2 (E2) at +10.6 kb downstream inside intron 6; and enhancer region 3 (E3) +140 kb downstream of the translation start site. In the current study, we utilized CRISPR-Cas9 genome editing to further characterize these enhancers in a human AML cell line and identify the key transcription factors (TFs) associated with their function. To efficiently track MEIS1 expression levels, a GFP reporter, a P2A self-cleaving peptide tag and a hemagglutinin tag at its translation start site was introduced in a MEIS1 high expressing human AML cell line, U937. Then we introduced random mutations (Indels) along the MEIS1 locus utilizing a CRISPR-Cas9 mediated genome editing vector system in mono-allelic MEIS1-GFP-tagged U937 cells with special focus on the previously identified enhancer regions to find the key sequences important to the function of the MEIS1 enhancer regions. Two targeted regions yielding the highest proportion of GFP - cells corresponded to the E2 enhancer region within intron 6 and were referred to as E2.1 and E2.2. Using chromosome conformation capture (3C) assay, we detected a significantly decreased interaction (p=0.0022) between the promoter and the intron 6 region surrounding the E2 region in E2.2 targeted cells compared to the parental cells. Moreover, our data indicated that the DNA sequence within E2.2 is highly critical to this region's enhancer function which is further influenced by the larger genomic region surrounding the E2.1 gRNA targeted site. To identify TFs binding to the E2 region, we further scrutinized the E2.2 indel region for loss of TF binding sites. We performed TF prediction analysis and performed a protein pull down-mass spectrometry experiment to identify TF candidates. The overlap yielded a list of 7 TFs, each of which we targeted via CRISPR/Cas9. Reduction in GFP levels was only observed for FLI1 locus targeting but not for the other 6 TFs. Concordant reduction in MEIS1 and FLI1 levels were confirmed by immunoblotting. Additionally, chromatin immunoprecipitation (ChIP) followed by quantitative PCR revealed significant FLI1 enrichment at the promoter and at 3 sites surrounding the E2.2 region (p=0.0004) compared to 4 control regions scattered along the MEIS1 locus. Given a previous study indicating MEIS1 upregulation of FLI1 in normal hematopoiesis, we hypothesised that a positive feedback loop may exist between FLI1 and MEIS1 in AML. Since MEIS1 levels are frequently elevated in normal karyotype AML (CN-AML), we used the murine Hoxa9/Meis1 AML model as a surrogate for CN-AML and performed Meis1 ChIP-seq analysis. We detected direct Meis1 binding to the intronic region of the mouse Fli1 gene as well as other ETS factor loci, in Hoxa9/Meis1 cells. To better understand the clinical relevance of FLI1 in AML, we analyzed the Beat AML dataset. High FLI1 transcript levels correlated with adverse overall survival in CN-AML (p=0.044). Additionally, we observed a trend towards worse outcome with high FLI1 in the NPM1-mutated CN-AML subtype (p=0.069). We also observed a similar correlation in CN-AML for another ETS factor, ELF1, which we had previously shown to bind and upregulate MEIS1 expression in AML, suggesting a broader unrecognized role for ETS factors in AML. In summary, we have developed a rapid flow cytometry-based readout for the fine dissection and characterization of the cis-regulatory elements and associated TFs critical for MEIS1 transcription via CRISPR-Cas9 genetic manipulation. Our study revealed FLI1 as the candidate key regulator of MEIS1 expression and a positive correlation between FLI1 mRNA levels and worse overall survival in MEIS1-high AML subgroups. Disclosures No relevant conflicts of interest to declare.

1998 ◽  
Vol 329 (1) ◽  
pp. 165-174 ◽  
J. Michael ADAMS ◽  
B. Martin REICHEL ◽  
A. Ian KING ◽  
D. Mark MARSDEN ◽  
D. Matthew GREENWOOD ◽  

The adhesive proteins in the desmosome type of cell junction consist of two members of the cadherin superfamily, the desmogleins and desmocollins. Both desmogleins and desmocollins occur as at least three different isoforms with various patterns of expression. The molecular mechanisms controlling the differential expression of the desmosomal cadherin isoforms are not yet known. We have begun an investigation of desmoglein gene expression by cloning and analysing the promoters of the human genes coding for the type 1 and type 3 desmogleins (DSG1 and DSG3). The type 1 isoform is restricted to the suprabasal layers of the epidermis and is the autoantigen in the autoimmune blistering skin disease pemphigus foliaceous. The type 3 desmoglein isoform is also expressed in the epidermis, but in lower layers than the type 1 isoform, and is the autoantigen in pemphigus vulgaris. Phage ƛ genomic clones were obtained containing 4.2 kb upstream of the translation start site of DSG1 and 517 bp upstream of the DSG3 start site. Sequencing of 660 bp upstream of DSG1 and 517 bp upstream of DSG3 revealed that there was no obvious TATA box, but a possible CAAT box was present at -238 in DSG1 and at -193 in DSG3 relative to the translation start site. Primer extension analysis and RNase protection experiments revealed four putative transcription initiation sites for DSG1 at positions -163, -151, -148 and -141, and seven closely linked sites for DSG3, the longest being at -140 relative to the translation start site. The sequences at these possible sites at -166 to -159 in DSG1 (TTCAGTCC) and at -124 to -117 in DSG3 (CTTAGACT) have some similarity to the initiator sequence (CTCANTCT) described for a TATA-less promoter often from -3 to +5, and the true transcription initiator site might therefore be the A residue in these sequences. There were two regions of similarity between the DSG1 and DSG3 promoters just upstream of the transcription initiation sites, of 20 and 13 bp, separated by 41 bp in DSG1 and 36 bp in DSG3. The significance of these regions of similarity remains to be elucidated, but the results suggest that they represent a point at which these two desmoglein genes are co-ordinately regulated. Analysis of the upstream sequences revealed GC-rich regions and consensus binding sites for transcription factors including AP-1 and AP-2. Exon boundaries were conserved compared with the classical cadherin E-cadherin, but the equivalent of the second cadherin intron was lacking. A 4.2 kb region of the human DSG1 promoter sequence was linked to the lacZ gene reporter gene in such a way that there was only one translation start site, and this construct was used to generate transgenic mice. We present the first transgenic analysis of a promoter region taken from a desmosomal cadherin gene. Our results suggest that the 4.2 kb upstream region of DSG1 does not contain all the regulatory elements necessary for correct expression of this gene but might have elements that regulate activity during hair growth.

2009 ◽  
Vol 24 (5-6) ◽  
pp. 335-346 ◽  
Anabela S. Ramalho ◽  
Marzena A. Lewandowska ◽  
Carlos M. Farinha ◽  
Filipa Mendes ◽  
Juan Gonçalves ◽  

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