Gerard Ruiz-Babot

IGSF10 mutations dysregulate gonadotropin‐releasing hormone neuronal migration resulting in delayed puberty

Early or late pubertal onset affects up to 5% of adolescents and is associated with adverse health and psychosocial outcomes. Self‐limited delayed puberty (DP) segregates predominantly in an autosomal dominant pattern, but the underlying genetic background is unknown. Using exome and candidate gene sequencing, we have identified rare mutations in IGSF10 in 6 unrelated families, which resulted in intracellular retention with failure in the secretion of mutant proteins. IGSF10 mRNA was strongly expressed in embryonic nasal mesenchyme, during gonadotropin‐releasing hormone (GnRH) neuronal migration to the hypothalamus. IGSF10 knockdown caused a reduced migration of immature GnRH neurons in vitro, and perturbed migration and extension of GnRH neurons in a gnrh3:EGFP zebrafish model. Additionally, loss‐of‐function mutations in IGSF10 were identified in hypothalamic amenorrhea patients. Our evidence strongly suggests that mutations in IGSF10 cause DP in humans, and points to a common genetic basis for conditions of functional hypogonadotropic hypogonadism (HH). While dysregulation of GnRH neuronal migration is known to cause permanent HH, this is the first time that this has been demonstrated as a causal mechanism in DP.

New Directions for the Treatment of Adrenal Insufficiency

Adrenal disease, whether primary, caused by defects in the hypothalamic–pituitary–adrenal (HPA) axis, or secondary, caused by defects outside the HPA axis, usually results in adrenal insufficiency, which requires lifelong daily replacement of corticosteroids. However, this kind of therapy is far from ideal as physiological demand for steroids varies considerably throughout the day and increases during periods of stress. The development of alternative curative strategies is therefore needed. In this review, we describe the latest technologies aimed at either isolating or generating de novo cells that could be used for novel, regenerative medicine application in the adrenocortical field.

Expression of progenitor markers is associated with the functionality of a bioartificial adrenal cortex

Encapsulation of primary bovine adrenocortical cells in alginate is an efficacious model of a bioartificial adrenal cortex. Such a bioartificial adrenal cortex can be used for the restoration of lost adrenal function in vivo as well as for in vitro modeling of the adrenal microenvironment and for investigation of cell–cell interactions in the adrenals. The aim of this work was the optimization of a bioartificial adrenal cortex, that is the generation of a highly productive, self-regenerating, long-term functioning and immune tolerant bioartificial organ. To achieve this, it is necessary that adrenocortical stem and progenitor cells are present in the bioartificial gland, as these undifferentiated cells play important roles in the function of the mature gland. Here, we verified the presence of adrenocortical progenitors in cultures of bovine adrenocortical cells, studied the dynamics of their appearance and growth and determined the optimal time point for cell encapsulation. These procedures increased the functional life span and reduced the immunogenicity of the bioartificial adrenal cortex. This model allows the use of the luteinizing hormone-releasing hormone (LHRH) agonist triptorelin, the neuropeptide bombesin, and retinoic acid to alter cell number and the release of cortisol over long periods of time.

Modeling Congenital Adrenal Hyperplasia and Testing Interventions for Adrenal Insufficiency Using Donor-Specific Reprogrammed Cells

Summary Adrenal insufficiency is managed by hormone replacement therapy, which is far from optimal; the ability to generate functional steroidogenic cells would offer a unique opportunity for a curative approach to restoring the complex feedback regulation of the hypothalamic-pituitary-adrenal axis. Here, we generated human induced steroidogenic cells (hiSCs) from fibroblasts, blood-, and urine-derived cells through forced expression of steroidogenic factor-1 and activation of the PKA and LHRH pathways. hiSCs had ultrastructural features resembling steroid-secreting cells, expressed steroidogenic enzymes, and secreted steroid hormones in response to stimuli. hiSCs were viable when transplanted into the mouse kidney capsule and intra-adrenal. Importantly, the hypocortisolism of hiSCs derived from patients with adrenal insufficiency due to congenital adrenal hyperplasia was rescued by expressing the wild-type version of the defective disease-causing enzymes. Our study provides an effective tool with many potential applications for studying adrenal pathobiology in a personalized manner and opens venues for the development of precision therapies.

HS6ST1 insufficiency causes self-limited delayed puberty in contrast with other GnRH deficiency genes.

Abstract Context Self-limited delayed puberty (DP) segregates in an autosomal-dominant pattern, but the genetic basis is largely unknown. Although DP is sometimes seen in relatives of patients with hypogonadotropic hypogonadism (HH), mutations in genes known to cause HH that segregate with the trait of familial self-limited DP have not yet been identified. Objective To assess the contribution of mutations in genes known to cause HH to the phenotype of self-limited DP. Design, Patients, and Setting We performed whole-exome sequencing in 67 probands and 93 relatives from a large cohort of familial self-limited DP, validated the pathogenicity of the identified gene variant in vitro, and examined the tissue expression and functional requirement of the mouse homolog in vivo. Results A potentially pathogenic gene variant segregating with DP was identified in 1 of 28 known HH genes examined. This pathogenic variant occurred in HS6ST1 in one pedigree and segregated with the trait in the six affected members with heterozygous transmission (P = 3.01 × 10−5). Biochemical analysis showed that this mutation reduced sulfotransferase activity in vitro. Hs6st1 mRNA was expressed in peripubertal wild-type mouse hypothalamus. GnRH neuron counts were similar in Hs6st1+/− and Hs6st1+/+ mice, but vaginal opening was delayed in Hs6st1+/− mice despite normal postnatal growth. Conclusions We have linked a deleterious mutation in HS6ST1 to familial self-limited DP and show that heterozygous Hs6st1 loss causes DP in mice. In this study, the observed overlap in potentially pathogenic mutations contributing to the phenotypes of self-limited DP and HH was limited to this one gene.

Role of IGSF10 mutations in self-limited delayed puberty

Abstract Background Abnormal timing of puberty affects over 4% of adolescents and is associated with adverse health and psychosocial outcomes. Previous studies estimate that 60–80% of variation in the timing of pubertal onset is genetically determined. However, little is known about the genetic control of human puberty. Self-limited delayed puberty segregates in an autosomal dominant pattern; our study aimed to identify novel genetic regulators of disease in these patients. Methods We performed whole-exome sequencing in 18 families with self-limited delayed puberty from our cohort, followed by candidate gene sequencing in a further 42 families. The functional consequences of the identified mutations in one candidate gene were interrogated via expression of wild type and mutant proteins in mammalian cells. For this gene we defined tissue expression in human and mouse embryos. The effects of gene knockdown were assessed via in-vitro neuronal migration assays, and in vivo with a transgenic zebrafish model. Findings In ten unrelated families, we identified four rare mutations in IGSF10 in individuals with self-limited delayed puberty (adjusted p value after rare variant burden testing=3·4 × 10 –2 ). The identified mutations were in evolutionarily conserved positions, and two mutations resulted in intracellular retention with failure in secretion of the N-terminal fragment of the protein. IGSF10 mRNA was strongly expressed in the nasal mesenchyme in mouse and human embryos during migration of gonadotropin-releasing hormone (GnRH) neurons from their nasal origin towards the hypothalamus. IGSF10 knockdown caused reduced migration of immature GnRH neurons in the in-vitro analysis, and perturbed migration and extension of GnRH neurons in the zebrafish model. Interpretation Our findings strongly support the contention that mutations in IGSF10 cause delayed puberty in human beings, through misregulation of GnRH neuronal migration during embryonic development. Funding Wellcome Trust (102745), Rosetrees Trust (M222), and the Barts and the London Charity (417/1551) (SH); Biotechnology and Biological Sciences Research Council (BB/L002671/1) (LG and GB); LD is partly supported by the Academy of Finland (14135); National Institutes for Health Research (NIHR) (MB, HW, and CC); Medical Research Council (MR/K021613/1) (AD); Telethon Foundation (GP13142) (AC); VA is partly supported by a COST STSM (BM1105-16145) and a travel grant sponsored by Development (The Company of Biologists Ltd).