A Novel Homozygous TTC7A Missense Mutation Results in Familial Multiple Intestinal Atresia and Combined Immunodeficiency

Rare autosomal-recessive variants in tetratricopeptide repeat domain 7A (TTC7A) gene have been shown to cause intestinal and immune disorders of variable severity. Missense mutations in TTC7A gene, usually retaining most of the functional motifs, is associated with relative milder clinical presentations. In this study, we reported a patient who was suffering from severe multiple intestinal atresia (MIA) with combined immunodeficiency (CID) that led to the pyloric diaphragm, ileum atresia, colon stenosis, and multiple episodes of sepsis. In spite of several surgeries and supportive treatment, the patient died of severe sepsis and multiple organ failure at age of 3 months. The whole exome sequencing (WES) of peripheral blood samples identified a novel homozygous TTC7A missense mutation (c. 206T>C, p. L69P), inherited from his parents with consanguineous marriage. In silico analysis revealed that a hydrogen bond present between Gly65 and Leu69 in the wild-type TTC7A was disrupted by the Leu69Pro mutation. Moreover, this homozygous missense mutation led to a reduced TTC7A expression in lymphocytes and intestinal tissues, accompanied by impeded lymphocyte development. Further studies demonstrated that the PI4K-FAM126A-EFR3A pathway was impaired in colon tissues. Our data strongly support the linkage of severe MIA-CID with the missense mutation in TTC7A gene. More knowledge of the TTC7A protein functions will have important therapeutic implications for patients with MIA-CID.

Evaluation of the Role of p53 Tumour Suppressor Posttranslational Modifications and TTC5Cofactor in Lung Cancer

Mutations in the p53 tumor suppressor are found in over 50% of cancers. p53 function is controlled through posttranslational modifications and cofactor interactions. In this study, we investigated the posttranslationally modified p53, including p53 acetylated at lysine 382 (K382), p53 phosphorylated at serine 46 (S46), and the p53 cofactor TTC5/STRAP (Tetratricopeptide repeat domain 5/ Stress-responsive activator of p300-TTC5) proteins in lung cancer. Immunohistochemical (IHC) analysis of lung cancer tissues from 250 patients was carried out and the results were correlated with clinicopathological features. Significant associations between total or modified p53 with a higher grade of the tumour and shorter overall survival (OS) probability were detected, suggesting that mutant and/or modified p53 acts as an oncoprotein in these patients. Acetylated at K382 p53 was predominantly nuclear in some samples and cytoplasmic in others. The localization of the K382 acetylated p53 was significantly associated with the gender and grade of the disease. The TTC5 protein levels were significantly associated with the grade, tumor size, and node involvement in a complex manner. SIRT1 expression was evaluated in 50 lung cancer patients and significant positive correlation was found with p53 S46 intensity, whereas negative TTC5 staining was associated with SIRT1 expression. Furthermore, p53 protein levels showed positive association with poor OS, whereas TTC5 protein levels showed positive association with better OS outcome. Overall, our results indicate that an analysis of p53 modified versions together with TTC5 expression, upon testing on a larger sample size of patients, could serve as useful prognostic factors or drug targets for lung cancer treatment.

Differential expression of TTC28 in cancer of the vulva.

In these brief notes we document work using published microarray data (1, 2) to pioneer integrative transcriptome analysis comparing vulvar carcinoma to its tissue of origin, the vulva. We report the differential expression of tetratricopeptide repeat domain 28, encoded by TTC28, in cancer of the vulva. TTC28 may be of pertinence to understanding transformation and disease progression in vulvar cancer (3).

TTC5 expression associates with survival in triple negative breast cancer.

We mined published microarray data (1) to understand the most significant gene expression differences in the tumors of triple negative breast cancer patients based on survival following treatment: dead or alive. We observed significant transcriptome-wide differential expression of tetratricopeptide repeat domain 5, encoded by TTC5 when comparing the primary tumors of triple negative breast cancer patients dead or alive. Importantly, TTC5 expression was correlated with recurrence-free survival in patients with breast cancer. TTC5 may be of relevance as a biomarker or as a molecule of interest in understanding the etiology or progression of triple negative breast cancer.

Case Report: Novel Compound-Heterozygous Variants of SKIV2L Gene that Cause Trichohepatoenteric Syndrome 2

Background: Trichohepatoenteric syndrome (THES) is a rare disease that mainly causes intractable diarrhea. It is classified into THES1 and THES2, which are associated with the tetratricopeptide repeat domain 37 (TTC37) gene and Ski2-like RNA helicase (SKIV2L) gene, respectively. THES is not very prevalent in China or worldwide, but new cases have increasingly been reported.Methods and Results: Here, we report the clinical and genetic information of a 1.5-month-old girl who was admitted to our hospital due to diarrhea and failure to thrive. Whole-exome sequencing (WES) revealed novel compound-heterozygous variants of the SKIV2L gene, c.3602_3609delAGCGCCTG (p.Q1201Rfs*2), and c.1990A > G (p.T664A) as the causative factors, which were confirmed via Sanger sequencing. Upon continuous feeding with an amino-acid formula through a gastric tube and parenteral nutrition, the patient resumed thriving and her stool frequency decreased.Conclusion: We report a girl carrying novel variants of the SKIV2L gene that cause THES2, thereby providing valuable information on the diagnosis of THES2 and expanding the spectrum of disease-causing SKIV2L mutations.

Structures of a deAMPylation complex rationalise the switch between antagonistic catalytic activities of FICD

The endoplasmic reticulum (ER) Hsp70 chaperone BiP is regulated by AMPylation, a reversible inactivating post-translational modification. Both BiP AMPylation and deAMPylation are catalysed by a single ER-localised enzyme, FICD. Here we present crystallographic and solution structures of a deAMPylation Michaelis complex formed between mammalian AMPylated BiP and FICD. The latter, via its tetratricopeptide repeat domain, binds a surface that is specific to ATP-state Hsp70 chaperones, explaining the exquisite selectivity of FICD for BiP’s ATP-bound conformation both when AMPylating and deAMPylating Thr518. The eukaryotic deAMPylation mechanism thus revealed, rationalises the role of the conserved Fic domain Glu234 as a gatekeeper residue that both inhibits AMPylation and facilitates hydrolytic deAMPylation catalysed by dimeric FICD. These findings point to a monomerisation-induced increase in Glu234 flexibility as the basis of an oligomeric state-dependent switch between FICD’s antagonistic activities, despite a similar mode of engagement of its two substrates — unmodified and AMPylated BiP.

A Novel Homozygous TTC7A Missense Mutation Results In Familial Multiple Intestinal Atresia And Combined Immunodeficiency

Multiple intestinal atresia with combined immune deficiency (MIA-CID) are autosomal recessive disorders characterized by intestinal obstructions and profound immune defects. The study of patients with MIA and related disorders has established that tetratricopeptide repeat domain 7A (TTC7A) plays a critical role in intestinal and immune homeostasis and it is now shown that biallelic missense mutations have better survival outcomes. However, clues to related underlying molecular dysfunction remains elusive. In this study, we reported a patient with the diagnosis of severe CID and MIA that involved the pyloric diaphragm, ileum atresia, and colon stenosis, and the clinical course was complicated by multiple episodes of sepsis. In spite of multiple surgeries and supportive treatment, the patient died of severe sepsis and multiple organ failure at 3 months of age. The whole exome sequencing (WES) identified a novel homozygous TTC7A missense mutation (c.206T>C, p. L69P). The structural analysis showed that a hydrogen bond present between Gly65 and Leu69 in the wild-type TTC7A was broken by the Leu69Pro mutation. Moreover, this homozygous missense mutation led to a severely reduced TTC7A expression in lymphocytes and intestinal tissues, accompanied by prohibited lymphocyte development. Further studies demonstrated that the PI4K-FAM126A-EFR3A pathway was impaired in intestinal tissues. Our results strongly suggest that the missense mutation in TTC7A gene causes severe MIA-CID. More knowledge of the TTC7A protein functions will have important therapeutic implications for patients with MIA-CID.

Identification of the TTC26 Splice Variant in a Novel Complex Ciliopathy Syndrome with Biliary, Renal, Neurological, and Skeletal Manifestations

Ciliopathies constitute heterogeneous disorders that result from mutations in ciliary proteins. These proteins play an important role in the development of organs, physiology, and signaling pathways, and sequence variations in the genes encoding these proteins are associated with multisystem disorders. In this study, we describe a severe ciliopathy disorder that segregates in an autosomal recessive manner in a nonconsanguineous Saudi family. The proband exhibited features such as cholestasis, cystic dilatation of intrahepatic biliary ducts, diabetes insipidus, dysmorphic facial features, optic atrophy, pituitary hypoplasia, hydrocephalus, aqueductal stenosis, hyperextensible knee joints, bilateral knee dislocation, polydactyly, and syndactyly. Whole-genome sequencing and Sanger sequencing revealed a homozygous splice site variant (c.4–1G&#x3e;C; NM_024926.3) in the tetratricopeptide repeat domain 26 (<i>TTC26</i>) gene located in chromosome 7q34, which cosegregated perfectly with the disease phenotype. qRT-PCR revealed a substantial decrease in the expression of the <i>TTC26</i> gene as compared to the normal control, suggesting the pathogenicity of the identified variant. This report further strengthens the evidence that homozygous variants in the <i>TTC26</i> gene cause severe ciliopathies with diverse phenotypes. We named this newly characterized condition as BRENS syndrome, which stands for biliary, renal, neurological, and skeletal features.