Original ArticleDegenerated hair follicle cells and partial loss of sebaceous and eccrine glands in a familial case of axenfeld-rieger syndrome: An emerging role for the FOXC1/NFATC1 genetic axis
Introduction
Congenital heart diseases (CHD) are the leading cause of death during the first year of life in humans worldwide, with an incidence of 1 in 100 [1,2]. Despite the tremendous progress in the clinical care of patients, and the technological progress in diagnosis and surgery, the genetic insight of such diseases is still scarce [[3], [4], [5], [6], [7]]. One of the main challenges is to properly analyze all the variants in the genes using a network approach that would take into account the functional and evolutionary interactions of the proteins in the cellular context. In all cases, an a priori knowledge of the molecular and developmental events that shape up the cellular defect inside the given organ is crucial. Lineage-specific transcription factors not only can control cell fate, but also structurally affect the development of a given organ when expressed at particular doses and appropriate timing. Amongst such transcription factors, the forkhead family of helix-turn-helix have been shown to be involved in organogenesis at different levels: cellular proliferation, differentiation, migration, and programmed cell death [8]. The murine Foxc1 protein was shown to be expressed particularly in the mesoderm as well as in derivatives of the neural crest cells in different organs including the eye, the heart, the brain, and recently the skin [[9], [10], [11]]. Foxc1 -/- mice die directly after birth or during the late stages of development mainly from cerebovascular defects [[12], [13], [14], [15]]. In humans, deleterious mutations in FOXC1 lead to the Axenfeld-Rieger Syndrome (OMIM#602482), that manifests amongst others with anterior segment dysgenesis at the level of the eye, leading to glaucoma, with subtle cardiac defects, mainly atrial septal defects (ASD) [16,17]. Despite extensive in vitro studies to assess the underlying strcutrual and functional defects in the mutant FOXC1 proteins, a genotype-phenotype correlation could not be established to explain the variable expressivity of the phenotype [18,19]. This might be due to FOXC1 being expressed in various cellular contexts at different timings, and that members for the same family might partially compensate for its expression and/or function. One close member is FOXC2 whose expression often overlaps with that of FOXC1 in numerous cells mainly in neural crest derivative cells [12,13,20,21].
Only recently, we started to gain more knowledge about the function of Foxc1 using mouse models [[22], [23], [24]]. The murine Foxc1 gene was shown to be expressed both in hair follicle stem cells and sebaceous glands. Loss of function of this gene resulted in the premature decay of the hair follicle cells by affecting the NFATC1/calcineurin pathway. Interestingly, the deletion of Foxc1 in activated, but not quiescent cells allow their premature activation, while its targeted inactivation in the bulge leads to loss of the old hair without impairing quiescence [23,24]. Finally, the targeted deletion of Foxc1 from the skin, lead to hypohidrotic mice, a phenotype that resembles the human sweat retention disorder, miliaria [22].
In this report, using whole exome sequencing we describe the first human cutaneous phenotype associated with a potential gain of function mutation in FOXC1 in a familial case of ARS with a highly penetrant ocular and cardiac phenotype. The degeneration of the hair follicle and the miniaturization/absence of sebaceous glands as well as incomplete development of the eccrine glands in affected individuals, were directly linked to the novel frameshift mutation in FOXC1. Our extensive genetic analyses identified a second rare variant in the NFATC1 which in our in vitro functional studies showed an indirect interaction with the FOXC1 mutant.
Section snippets
Patients recruitment
This study was approved by the institutional review board (IRB) at the American University of Beirut (AUB) under protocol number Bioc.GN.01. All members of the family patients signed an informed ascent and/or consent form before being enrolled in the study. Blood samples were collected from all five members of the family.
Exome sequencing and data analysis
One microgram of extracted DNA samples from all family members was sent to Macrogen (www.dna.macrogen.com) where exome sequencing was performed using the V6 Sureselect target
Clinical evaluation: cardiac, ocular, and cutaneous anomalies
The indexed patients, identical-twin boys were diagnosed after birth with cardiac and ocular defects (Fig. 1a). Patient II-2 was referred to our center for ocular defects and was diagnosed with congenital glaucoma and aniridia at the age of 25 days (Fig. 1b). He underwent trabeculectomy at the age of 2 months to both eyes, and corneal transplantation was performed successfully sequentially in both eyes. Cardiac echocardiography showed a minimal apical displacement of the tricuspid valve and an
Discussion
This is the first report on a familial case of ARS with a cutaneous phenotype that is caused by a double gain of function mutations in NFATC1 and FOXC1. Our working hypothesis on the polygenic basis of congenital heart disease is expanding towards other inherited diseases, and would hopefully clarify the complex genetic basis of non-monogenic syndromes. The key to such a successive strategy is both related to the proper clinical characterization of the defect(s) in the affected individuals, and
Acknowledgements
We thank all members of the indexed family for their participation in the study. We also thank Dr. Mike Walter for the FOXC1 expression plasmid. Special thanks to Mrs. Inaam El-Rassy in the Molecular Core facility for Sanger sequencing. This work was supported by an MPP/URB grant from the American University of Beirut.
References (35)
- et al.
The incidence of congenital heart disease
J. Am. Coll. Cardiol.
(2002) - et al.
Roles for the winged helix transcription factors MF1 and MFH1 in cardiovascular development revealed by nonallelic noncomplementation of null alleles
Dev. Biol.
(1999) - et al.
The forkhead/winged helix gene Mf1 is disrupted in the pleiotropic mouse mutation congenital hydrocephalus
Cell
(1998) - et al.
Mutations of the forkhead/winged-helix gene, FKHL7, in patients with Axenfeld-Rieger anomaly
Am. J. Hum. Genet.
(1998) - et al.
Forkhead transcription factors, Foxc1 and Foxc2, are required for the morphogenesis of the cardiac outflow tract
Dev. Biol.
(2006) - et al.
Foxc1 ablated mice are anhidrotic and recapitulate features of human Miliaria sweat retention disorder
J. Invest. Dermatol.
(2017) - et al.
Analyses of the effects that disease-causing missense mutations have on the structure and function of the winged-helix protein FOXC1
Am. J. Hum. Genet.
(2001) - et al.
Small ubiquitin-like modifier (SUMO) modification mediates function of the inhibitory domains of developmental regulators FOXC1 and FOXC2
J. Biol. Chem.
(2012) - et al.
NFATc1 balances quiescence and proliferation of skin stem cells
Cell
(2008) Genetic and congenital heart defects
Arch. Cardiol. Mex.
(2007)
Genetics of congenital heart disease: the contribution of the noncoding regulatory genome
J. Hum. Genet.
De novo mutations in congenital heart disease with neurodevelopmental and other congenital anomalies
Science
Increased frequency of de novo copy number variants in congenital heart disease by integrative analysis of single nucleotide polymorphism array and exome sequence data
Circ. Res.
Of mice and men: molecular genetics of congenital heart disease
Cell. Mol. Life Sci.
Genetics of congenital heart disease: the glass half empty
Circ. Res.
Fox transcription factors: from development to disease
Development
FOXC1: an emerging marker and therapeutic target for cancer
Oncogene
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