A complementary study approach unravels novel players in the pathoetiology of Hirschsprung disease

Abstract

Hirschsprung disease (HSCR, OMIM 142623) involves congenital intestinal obstruction caused by dysfunction of neural crest cells and their progeny during enteric nervous system (ENS) development. HSCR is a multifactorial disorder; pathogenetic variants accounting for disease phenotype are identified only in a minority of cases, and the identification of novel disease-relevant genes remains challenging. In order to identify and to validate a potential disease-causing relevance of novel HSCR candidate genes, we established a complementary study approach, combining whole exome sequencing (WES) with transcriptome analysis of murine embryonic ENS-related tissues, literature and database searches, in silico network analyses, and functional readouts using candidate gene-specific genome-edited cell clones. WES datasets of two patients with HSCR and their non-affected parents were analysed, and four novel HSCR candidate genes could be identified: ATP7A, SREBF1, ABCD1 and PIAS2. Further rare variants in these genes were identified in additional HSCR patients, suggesting disease relevance. Transcriptomics revealed that these genes are expressed in embryonic and fetal gastrointestinal tissues. Knockout of these genes in neuronal cells demonstrated impaired cell differentiation, proliferation and/or survival. Our approach identified and validated candidate HSCR genes and provided further insight into the underlying pathomechanisms of HSCR.

Differentiation and Subtype Specification of Enteric Neurons: Current Knowledge of Transcription Factors, Signaling Molecules and Signaling Pathways Involved

“…While the vagal NCCs are colonizing the entire length of the GI tract, the sacral NCCs show a small contribution to the ENS by colonizing the postumbilical region [9,18]. Between embryonic day (E) 8.5 and 9.5 in mice, and before the 4 th week of pregnancy in humans, NCCs delaminate from the neural crest and become progenitors for multiple cell types among which the enteric neurons [11,[19][20][21]. After delamination, the vagal NCCs start to migrate towards the developing foregut.…”

“…Once arrived, they are called enteric neural crest cells (ENCCs) and are characterized by the expression of multiple factors, such as Sox10, Phoxb2, Ednrb and Ascl1. The ENCCs will then further migrate in the GI tissue, proliferate, and colonize the entire length of the GI tract and form neuronal and glial precursors [9,21,22]. The sacral NCCs migrate ventrally and will form extrinsic pelvic ganglia.…”

The enteric nervous system in gastrointestinal disease etiology

“…Collectively, genetic studies of patients with HSCR [32][33][34] and in vivo transgenic animal models [35][36][37] have identified multiple genes involved in the development of the ENS, including the receptor tyrosine kinase (RET) [38,39] and endothelin receptor type B (EDNRB) [40] and their family members as major players for the HSCR phenotype, together with mutations in SOX10 [41,42], PHOX2B [43], semaphorins [44,45], among other genes [46]. Interestingly, recent studies revealed other molecular HSCR candidates [47] and genetic variants, including pathogenic genes, alleles and loci that can exacerbate the susceptibility of HSCR patients in manifesting the disease phenotype [48,49]. Highly conserved among species, deficiencies along the signaling pathways of these genes may result in failure of ENS progenitors to migrate, proliferate, differentiate or survive within the distal intestine and cause congenital bowel obstruction [5,50].…”

Chasing the Target: New Phenomena of Resistance to Novel Selective RET Inhibitors in Lung Cancer. Updated Evidence and Future Perspectives

“…Genitourinary and nervous system development [ 10 , 11 ], maturation and migration of stem cell lines and a general involvement in embryogenesis and spermatogenesis, represent the main known mechanisms in which RET’s signaling is involved during embryonic development [ 12 , 13 ]. It’s clearly understandable how RET loss of function due to germline mutations, affecting those mechanism, can lead to a variety of congenital malformations such as Hirschsprung disease (HSCR) and congenital abnormalities of the kidney and urinary tract (CAKUT), and cause numerous symptoms in patients with phenotypic variants of these syndromes [ 14 , 15 ]. However, a role for RET in maintenance of hematopoietic system and in development of Gut-Associated Lymphoid Tissue (GALT) has recently been recognized [ 16 ].…”