Diverse molecular causes of unsolved autosomal dominant tubulointerstitial kidney diseases.

Autosomal Dominant Tubulointerstitial Kidney Disease (ADTKD) is caused by mutations in one of at least five genes and leads to kidney failure usually in mid adulthood. Throughout the literature, variable numbers of families have been reported, where no mutation can be found and therefore termed ADTKD-not otherwise specified. Here, we aim to clarify the genetic cause of their diseases in our ADTKD registry. Sequencing for all known ADTKD genes was performed, followed by SNaPshot minisequencing for the dupC (an additional cytosine within a stretch of seven cytosines) mutation of MUC1. A virtual panel containing 560 genes reported in the context of kidney disease (nephrome) and exome sequencing were then analyzed sequentially. Variants were validated and tested for segregation. In 29 of the 45 registry families, mutations in known ADTKD genes were found, mostly in MUC1. Sixteen families could then be termed ADTKD-not otherwise specified, of which nine showed diagnostic variants in the nephrome (four in COL4A5, two in INF2 and one each in COL4A4, PAX2, SALL1 and PKD2). In the other seven families, exome sequencing analysis yielded potential disease associated variants in novel candidate genes for ADTKD; evaluated by database analyses and genome-wide association studies. For the great majority of our ADTKD registry we were able to reach a molecular genetic diagnosis. However, a small number of families are indeed affected by diseases classically described as a glomerular entity. Thus, incomplete clinical phenotyping and atypical clinical presentation may have led to the classification of ADTKD. The identified novel candidate genes by exome sequencing will require further functional validation.

Relaxation of glycine receptor and onconeural gene transcription control in NRSF deficient small cell lung cancer cell lines.

Negative regulation of many neuronal genes is mediated by the neuron-restrictive silencer factor (NRSF/repressor element-1 binding transcription factor, REST), which binds to the neuron-restrictive silencer element (NRSE/repressor element-1, RE-1) and thereby represses transcription of neuronal genes in non-neuronal cells. Sequence analysis of 5'-flanking regions of glycine receptor (GlyR) subunit genes revealed a consensus motif for NRSE in the GLRA1 and GLRA3, but not in GLRB, genes. In this study, we examined tumor cell lines for the expression of NRSF, GlyR subunits and onconeural genes. We identified two small cell lung cancer (SCLC) cell lines lacking full-length NRSF/REST as well as its neuronal splice variants. Presence or absence of NRSF as well as its functionality in different SCLC cell lines was additionally shown in reporter gene assays. As GlyR alpha1 is selectively transcribed in NRSF/REST free cells, GlyR alpha1 transcripts might serve as positive signals for NRSF deficient cells. In contrast, GlyR beta is nearly ubiquitously transcribed in the cell lines analyzed and, therefore, should represent a useful marker for neoplastic cells. Sequence analysis of GlyR beta transcripts led to the identification of a new splice variant lacking exon 8, GlyR beta Delta8. This suggests that the lack of NRSF in SCLC cells, resulting in the relaxation of neuronal gene suppression, is an important mechanism underlying paraneoplastic expression.