Molecular Signature of CAID Syndrome: Noncanonical Roles of SGO1 in Regulation of TGF-β Signaling and Epigenomics

Abstract

Background & AimsA generalized human pacemaking syndrome, chronic atrial and intestinal dysrhythmia (CAID) (OMIM 616201), is caused by a homozygous SGO1 mutation (K23E), leading to chronic intestinal pseudo-obstruction and arrhythmias. Because CAID patients do not show phenotypes consistent with perturbation of known roles of SGO1, we hypothesized that noncanonical roles of SGO1 drive the clinical manifestations observed.MethodsTo identify a molecular signature for CAID syndrome, we achieved unbiased screens in cell lines and gut tissues from CAID patients vs wild-type controls. We performed RNA sequencing along with stable isotope labeling with amino acids in cell culture. In addition, we determined the genome-wide DNA methylation and chromatin accessibility signatures using reduced representative bisulfite sequencing and assay for transposase-accessible chromatin with high-throughput sequencing. Functional studies included patch-clamp, quantitation of transforming growth factor-β (TGF-β) signaling, and immunohistochemistry in CAID patient gut biopsy specimens.ResultsProteome and transcriptome studies converge on cell-cycle regulation, cardiac conduction, and smooth muscle regulation as drivers of CAID syndrome. Specifically, the inward rectifier current, an important regulator of cellular function, was disrupted. Immunohistochemistry confirmed overexpression of Budding Uninhibited By Benzimidazoles 1 (BUB1) in patients, implicating the TGF-β pathway in CAID pathogenesis. Canonical TGF-β signaling was up-regulated and uncoupled from noncanonical signaling in CAID patients. Reduced representative bisulfite sequencing and assay for transposase-accessible chromatin with high-throughput sequencing experiments showed significant changes of chromatin states in CAID, pointing to epigenetic regulation as a possible pathologic mechanism.ConclusionsOur findings point to impaired inward rectifier potassium current, dysregulation of canonical TGF-β signaling, and epigenetic regulation as potential drivers of intestinal and cardiac manifestations of CAID syndrome. Transcript profiling and genomics data are as follows: repository URL: https://www.ncbi.nlm.nih.gov/geo; SuperSeries GSE110612 was composed of the following subseries: GSE110309, GSE110576, and GSE110601.

Cohesin-protein Shugoshin-1 controls cardiac automaticity via HCN4 pacemaker channel

“…All CAID patients were homozygous for a recessive point mutation (A > G) in SGO1 , leading to a lysine-to-glutamic acid change at the highly conserved amino acid 23 (p.Lys23Glut: SGO1-K23E). In contrast to other cohesinopathies, CAID-patients have no craniofacial or structural cardiac defects, nor premature ageing 12 . CAID-related symptoms appear to mainly, and postnatally, affect the heart and gut, suggesting that the SGO1-K23E mutation likely leads to a change of function with relatively mild, but cell-specific effects.…”

“…CAID-related symptoms appear to mainly, and postnatally, affect the heart and gut, suggesting that the SGO1-K23E mutation likely leads to a change of function with relatively mild, but cell-specific effects. To investigate the molecular mechanisms leading to CAID-related clinical manifestations, we recently performed multiomics studies on primary control versus patient-derived dermal fibroblasts, which pointed to canonical (i.e., cell cycling and epigenetic) as well as non-canonical changes in signaling pathways, including disturbed transforming growth-factor beta signaling and altered fibroblast ion-channel function 12 .…”

Pre-Implantation Alcohol Exposure Induces Lasting Sex-Specific DNA Methylation Programming Errors in the Developing Forebrain

“…Genomic DNA was used to produce rapid Reduced Representation Bisulfite Sequencing (rRRBS) libraries as previously described (L.-M. Legault, Chan, & McGraw, 2019;S. McGraw et al, 2015;Piché et al, 2019;Pierre, Legault, Londono, McGraw, & Lodygensky, 2020). Briefly, 500ng of DNA was digested with Msp1 restriction enzyme, adapters were attached to DNA fragments followed by sodium bisulfite conversion and amplification/indexation of libraries.…”

“…Data processing, alignment (mm10 genome) and methylation calls were performed using our established pipeline (L. M. Legault et al, 2020;S. McGraw et al, 2015;Piché et al, 2019;Pierre et al, 2020) which includes tools such as Trim Galore (version 0.3.3) (Krueger, 2012), BSMAP (version 2.90) (Xi & Li, 2009) and R (version 3.5.0). Differentially methylated regions were obtained with MethylKit (version 1.8.1) (Akalin et al, 2012) using the Benjamini-Hochberg false discovery rate (FDR) procedure.…”

Chronic Atrial Intestinal Dysrhythmia Syndrome Is Associated with Cerebral Small Vessel Disease and Predominantly Cerebellar Microbleeds

“…It is thought that disruption in functions other than chromatic cohesion could lead to the clinical manifestations of cohesinopathies. 2 Chetaille et al highlight upregulation of TGF-β signaling and fibrosis in intestinal biopsies of patients with the disease. 1 An association has been established between disturbed TGF-β signaling and multiple forms of CSVD (e.g., CADASIL).…”