Loss of the TRPM4 channel in humans causes immune dysregulation with defective monocyte migration.

BACKGROUND: TRPM4 is a broadly expressed, calcium-activated, monovalent cation channel that regulates immune cell function in mice and cell lines. Clinically, however, partial loss- or gain-of-function mutations in TRPM4 lead to arrhythmia and heart disease, with no documentation of immunologic disorders. OBJECTIVE: To characterize functional cellular mechanisms underlying the immune dysregulation phenotype in a proband with a mutated TRPM4 gene. METHODS: We employed a combination of biochemical, cell biological, imaging, omics analyses, flow cytometry, and gene editing approaches. RESULTS: We report the first human cases to our knowledge with complete loss of the TRPM4 channel, leading to immune dysregulation with frequent bacterial and fungal infections. Single-cell and bulk RNA sequencing point to altered expression of genes affecting cell migration, specifically in monocytes. Inhibition of TRPM4 in T cells and the THP-1 monocyte cell line reduces migration. More importantly, primary T cells and monocytes from TRPM4 patients migrate poorly. Finally, CRISPR knockout of TRPM4 in THP-1 cells greatly reduces their migration potential. CONCLUSION: Our results demonstrate that TRPM4 plays a critical role in regulating immune cell migration, leading to increased susceptibility to infections.

Retinal nerve fibre layer thinning and corneal nerve loss in patients with Bardet-Biedl syndrome.

BACKGROUND: Bardet-Biedl syndrome (BBS) is an autosomal recessive, genetically heterogeneous, pleiotropic disorder caused by variants in genes involved in the function of the primary cilium. We have harnessed genomics to identify BBS and ophthalmic technologies to describe novel features of BBS. CASE PRESENTATION: A patient with an unclear diagnosis of syndromic type 2 diabetes mellitus, another affected sibling and unaffected siblings and parents were sequenced using DNA extracted from saliva samples. Corneal confocal microscopy (CCM) and retinal spectral domain optical coherence tomography (SD-OCT) were used to identify novel ophthalmic features in these patients. The two affected individuals had a homozygous variant in C8orf37 (p.Trp185*). SD-OCT and CCM demonstrated a marked and patchy reduction in the retinal nerve fiber layer thickness and loss of corneal nerve fibers, respectively. CONCLUSION: This report highlights the use of ophthalmic imaging to identify novel retinal and corneal abnormalities that extend the phenotype of BBS in a patient with syndromic type 2 diabetes.

Regulation of Circular RNA CircNFATC3 in Cancer Cells Alters Proliferation, Migration, and Oxidative Phosphorylation.

Circular RNAs were once considered artifacts of transcriptome sequencing but have recently been identified as functionally relevant in different types of cancer. Although there is still no clear main function of circRNAs, several studies have revealed that circRNAs are expressed in various eukaryotic organisms in a regulated manner often independent of their parental linear isoforms demonstrating conservation across species. circNFATC3, an abundant and uncharacterized circular RNA of exon 2 and 3 from NFATC3, was identified in transcriptomic data of solid tumors. Here we show that circNFATC3 gain- and loss-of-function experiments using RNAi-mediated circRNA silencing and circular mini vector-mediated overexpression of circularized constructs in breast and ovarian cancer cell lines affect molecular phenotypes. The knockdown of circNFATC3 induces a reduction in cell proliferation, invasion, migration, and oxidative phosphorylation. Gain-of-function of circNFATC3 in MDA-MB-231 and SK-OV-3 cells show a significant increase in cell proliferation, migration, and respiration. The above results suggest that circNFATC3 is a functionally relevant circular RNA in breast and ovarian cancer.