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Mutations in RAD21 disrupt regulation of APOB in patients with chronic intestinal pseudo-obstruction.

ABSTRACT: Chronic intestinal pseudo-obstruction (CIPO) is characterized by severe intestinal dysmotility that mimics a mechanical subocclusion with no evidence of gut obstruction. We searched for genetic variants associated with CIPO to increase our understanding of its pathogenesis and to identify potential biomarkers.We performed whole-exome sequencing of genomic DNA from patients with familial CIPO syndrome. Blood and lymphoblastoid cells were collected from patients and controls (individuals without CIPO); levels of messenger RNA (mRNA) and proteins were analyzed by quantitative reverse-transcription polymerase chain reaction, immunoblot, and mobility shift assays. Complementary DNAs were transfected into HEK293 cells. Expression of rad21 was suppressed in zebrafish embryos using a splice-blocking morpholino (rad21a). Gut tissues were collected and analyzed.We identified a homozygous mutation (p.622, encodes Ala>Thr) in RAD21 in patients from a consanguineous family with CIPO. Expression of RUNX1, a target of RAD21, was reduced in cells from patients with CIPO compared with controls. In zebrafish, suppression of rad21a reduced expression of runx1; this phenotype was corrected by injection of human RAD21 mRNA, but not with the mRNA from the mutated p.622 allele. rad21a Morpholino zebrafish had delayed intestinal transit and greatly reduced numbers of enteric neurons, similar to patients with CIPO. This defect was greater in zebrafish with suppressed expression of ret and rad21, indicating their interaction in the regulation of gut neurogenesis. The promoter region of APOB bound RAD21 but not RAD21 p.622 Ala>Thr; expression of wild-type RAD21 in HEK293 cells repressed expression of APOB, compared with control vector. The gut-specific isoform of APOB (APOB48) is overexpressed in sera from patients with CIPO who carry the RAD21 mutation. APOB48 also is overexpressed in sporadic CIPO in sera and gut biopsy specimens.Some patients with CIPO carry mutations in RAD21 that disrupt the ability of its product to regulate genes such as RUNX1 and APOB. Reduced expression of rad21 in zebrafish, and dysregulation of these target genes, disrupts intestinal transit and the development of enteric neurons.

SUBMITTER: Bonora E

PROVIDER: S-EPMC4375026 | biostudies-literature | 2015 Apr

REPOSITORIES: biostudies-literature

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Mutations in RAD21 disrupt regulation of APOB in patients with chronic intestinal pseudo-obstruction.

Bonora Elena E Bianco Francesca F Cordeddu Lina L Bamshad Michael M Francescatto Ludmila L Dowless Dustin D Stanghellini Vincenzo V Cogliandro Rosanna F RF Lindberg Greger G Mungan Zeynel Z Cefle Kivanc K Ozcelik Tayfun T Palanduz Sukru S Ozturk Sukru S Gedikbasi Asuman A Gori Alessandra A Pippucci Tommaso T Graziano Claudio C Volta Umberto U Caio Giacomo G Barbara Giovanni G D'Amato Mauro M Seri Marco M Katsanis Nicholas N Romeo Giovanni G De Giorgio Roberto R

Gastroenterology 20150106 4

<h4>Background & aims</h4>Chronic intestinal pseudo-obstruction (CIPO) is characterized by severe intestinal dysmotility that mimics a mechanical subocclusion with no evidence of gut obstruction. We searched for genetic variants associated with CIPO to increase our understanding of its pathogenesis and to identify potential biomarkers.<h4>Methods</h4>We performed whole-exome sequencing of genomic DNA from patients with familial CIPO syndrome. Blood and lymphoblastoid cells were collected from pa ...[more]

PMID: 25575569

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Project description:BACKGROUND: Chronic idiopathic intestinal pseudo-obstruction, a syndrome of ineffectual motility due to a primary disorder of enteric nerve or muscle, is rare. AIMS: To determine the clinical spectrum, underlying pathologies, response to treatments, and prognosis in a consecutive unselected group of patients. METHODS: Cross sectional study of all patients with clinical and radiological features of intestinal obstruction in the absence of organic obstruction, associated with dilated small intestine (with or without dilated large intestine), being actively managed in one tertiary referral centre at one time. RESULTS: Twenty patients (11 men and nine women, median age 43 years, range 22-67) fulfilled the diagnostic criteria. Median age at onset of symptoms was 17 years (range two weeks to 59 years). Two patients had an autosomally dominant inherited visceral myopathy. Major presenting symptoms were pain (80%), vomiting (75%), constipation (40%), and diarrhoea (20%). Eighteen patients required abdominal surgery, and a further patient had a full thickness rectal biopsy. The mean time interval from symptom onset to first operation was 5.8 years. Histology showed visceral myopathy in 13, visceral neuropathy in three, and was indeterminate in three. In the one other patient small bowel motility studies were suggestive of neuropathy. Two patients died within two years of symptom onset, one from generalised thrombosis and the other from an inflammatory myopathy. Of the remaining 18 patients, eight were nutritionally independent of supplements, two had gastrostomy or jejunostomy feeds, and eight were receiving home parenteral nutrition. Five patients were opiate dependent, only one patient had benefited from prokinetic drug therapy, and five patients required formal psychological intervention and support. CONCLUSIONS: In a referral setting visceral myopathy is the most common diagnosis in this heterogeneous syndrome, the course of the illness is usually prolonged, and prokinetic drug therapies are not usually helpful. Ongoing management problems include pain relief and nutritional support.

Project description:Chronic intestinal pseudo-obstruction is a severe complication of systemic sclerosis. Inflammatory neuropathy and immunological alterations have a prominent role in the development of systemic sclerosis-related chronic intestinal pseudo-obstruction and immunomodulation might be beneficial in this context. An accidental observation of a patient with juvenile arthritis and a biopsy-proven diagnosis of autoimmune ganglionitis led us to experiment with a new approach to treat systemic sclerosis-related chronic intestinal pseudo-obstruction. In our arthritis patient, the severity and frequency of recurrent episodes of chronic intestinal pseudo-obstruction and aspiration pneumonia were reduced whenever steroids were used to treat arthritic flares, which dramatically improved with abatacept therapy. A systemic sclerosis patient presented typical chronic intestinal pseudo-obstruction features that were neither controlled by dietary interventions nor by prokinetics and were often complicated by acute episodes (5-year) requiring hospitalization. Increased food tolerance was observed whenever parenteral steroids were used during hospitalization. An adequate long-term control of symptoms was then obtained with the use of intramuscular methylprednisolone 20 mg/day; however, symptoms promptly recurred after tapering. Following this motivating example, immunomodulation with abatacept was started. Symptoms were then well controlled and steroids could be weaned off without further acute episodes of sub-occlusion. We postulate that inflammatory neuropathy resembling myenteric ganglionitis may be suspected in selected systemic sclerosis patients with chronic intestinal pseudo-obstruction features. Immunomodulation with drugs that act on T function and restore the regulatory/effector T cell balance may be beneficial in these subjects. The outcomes of four additional systemic sclerosis patients with severe and refractory symptoms of intestinal pseudo-obstruction successfully treated with abatacept are also presented.

Dataset Information

Mutations in RAD21 disrupt regulation of APOB in patients with chronic intestinal pseudo-obstruction.

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Mutations in RAD21 disrupt regulation of APOB in patients with chronic intestinal pseudo-obstruction.

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