A novel stop codon mutation in exon 5 (c.639G>A) of the cadherin-1 gene in a Vietnamese man with hereditary diffuse gastric cancer: a case report

Background

Germline pathogenic variants in the cadherin-1 (CDH1) gene cause a predisposition to hereditary diffuse gastric cancer (HDGC). We report an HDGC case in Vietnam and identify a novel mutation in the CDH1 gene.

Case presentation

A 28-year-old Vietnamese man was diagnosed with HDGC and a novel mutation at c.639G>A. All exons of CDH1 were sequenced in his pedigree, which revealed the c.639G>A mutation in the proband, his father, and uncle. The patient refused treatment and died 4 months after diagnosis. Endoscopic surveillance of the father and the uncle showed structural abnormalities in the father.

Conclusion

In cases of HDGC, identification of the CDH1 gene mutation is very important for better counseling and more effective strategies to prevent the development of diseases, such as prophylactic gastrectomy for family members with genetic mutations.

Hypervirulent Klebsiella pneumoniae infection in a woman with a CDH1 gene mutation

The CDH1 gene, which encodes E-cadherin, may be associated with cancer when mutated, but the significance of mutations in the context of infection is unknown. In this report, we describe a case of disseminated hypervirulent Klebsiella pneumoniae infection in a 49 year old Caucasian woman with a documented CDH1 mutation.

Onset of Spinal Cord Astrocyte Precursor Emigration from the Ventricular Zone Involves the Zeb1 Transcription Factor

During spinal cord development, astrocyte precursors arise from neuroepithelial progenitors, delaminate from the ventricular zone, and migrate toward their final locations where they differentiate. Although the mechanisms underlying their early specification and late differentiation are being deciphered, less is known about the temporal control of their migration. Here, we show that the epithelial-mesenchymal transition regulator Zeb1 is expressed in glial precursors and report that loss of Zeb1 function specifically delays the onset of astrocyte precursor delamination from the ventricular zone, correlating with transient deregulation of the adhesion protein Cadherin-1. Consequently, astrocyte precursor invasion into the Zeb1^-/- mutant white matter is delayed, and induction of their differentiation is postponed. These findings illustrate how fine regulation of adhesive properties influences the onset of neural precursor migration and further support the notion that duration of exposure of migrating astrocyte precursors to environmental cues and/or their correct positioning influence the timing of their differentiation.

Cortactin is a scaffolding platform for the E-cadherin adhesion complex and is regulated by protein kinase D1 phosphorylation

Dynamic regulation of cell-cell adhesion by the coordinated formation and dissolution of E-cadherin-based adherens junctions is crucial for tissue homeostasis. The actin-binding protein cortactin interacts with E-cadherin and enables F-actin accumulation at adherens junctions. Here, we were interested to study the broader functional interactions of cortactin in adhesion complexes. In line with literature, we demonstrate that cortactin binds to E-cadherin, and that a posttranslational modification of cortactin, RhoA-induced phosphorylation by protein kinase D1 (PKD1; also known as PRKD1) at S298, impairs adherens junction assembly and supports their dissolution. Two new S298-phosphorylation-dependent interactions were also identified, namely, that phosphorylation of cortactin decreases its interaction with β-catenin and the actin-binding protein vinculin. In addition, binding of vinculin to β-catenin, as well as linkage of vinculin to F-actin, are also significantly compromised upon phosphorylation of cortactin. Accordingly, we found that regulation of cell-cell adhesion by phosphorylation of cortactin downstream of RhoA and PKD1 is vitally dependent on vinculin-mediated protein interactions. Thus, cortactin, unexpectedly, is an important integration node for the dynamic regulation of protein complexes during breakdown and formation of adherens junctions.