FGFR1 and PROKR2 rare variants found in patients with combined pituitary hormone deficiencies

The genetic aetiology of congenital hypopituitarism (CH) is not entirely elucidated. FGFR1 and PROKR2 loss-of-function mutations are classically involved in hypogonadotrophic hypogonadism (HH), however, due to the clinical and genetic overlap of HH and CH; these genes may also be involved in the pathogenesis of CH. Using a candidate gene approach, we screened 156 Brazilian patients with combined pituitary hormone deficiencies (CPHD) for loss-of-function mutations in FGFR1 and PROKR2. We identified three FGFR1 variants (p.Arg448Trp, p.Ser107Leu and p.Pro772Ser) in four unrelated patients (two males) and two PROKR2 variants (p.Arg85Cys and p.Arg248Glu) in two unrelated female patients. Five of the six patients harbouring the variants had a first-degree relative that was an unaffected carrier of it. Results of functional studies indicated that the new FGFR1 variant p.Arg448Trp is a loss-of-function variant, while p.Ser107Leu and p.Pro772Ser present signalling activity similar to the wild-type form. Regarding PROKR2 variants, results from previous functional studies indicated that p.Arg85Cys moderately compromises receptor signalling through both MAPK and Ca2+ pathways while p.Arg248Glu decreases calcium mobilization but has normal MAPK activity. The presence of loss-of-function variants of FGFR1 and PROKR2 in our patients with CPHD is indicative of an adjuvant and/or modifier effect of these rare variants on the phenotype. The presence of the same variants in unaffected relatives implies that they cannot solely cause the phenotype. Other associated genetic and/or environmental modifiers may play a role in the aetiology of this condition.

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SAT-291 SIX3 Is Essential for Hypothalamic and Pituitary Development

Journal of the Endocrine Society ◽

10.1210/jendso/bvaa046.159 ◽

2020 ◽

Vol 4 (Supplement_1) ◽

Author(s):

Hironori Bando ◽

Michelle L Brinkmeier ◽

Frederic Castinetti ◽

Peter Gergics ◽

Amanda H Mortensen ◽

...

Keyword(s):

Bmp Signaling ◽

Pituitary Hormone ◽

Homeodomain Protein ◽

Loss Of Function ◽

Shh Signaling ◽

Rathke’S Pouch ◽

Pituitary Development ◽

Rathke's Pouch ◽

Oral Ectoderm ◽

Congenital Hypopituitarism

Abstract The genetic basis for congenital hypopituitarism and related disorders is beginning to emerge, and over causal 30 genes have been identified, including six in the SHH signaling pathway. Mutations in some of these genes can also cause holoprosencephaly (HPE) or septo-optic dysplasia. SIX3 is a homeodomain protein expressed in the developing brain, pituitary gland, and eye. It activates SHH signaling and represses BMP signaling. Heterozygous mutations in SIX3 cause variable HPE in humans and mice. We identified a rare, heterozygous variant in SIX3 in two children with neonatal GH and TSH deficiency and stalk interruption, p.P74R. Using transient transfection in 3T3 cells, we demonstrated that the variant reduced the ability of SIX3 to transactivate the SHH enhancer and promoter of FOXG1, suggesting that the variant could be deleterious. To understand the role of SIX3 in hypothalamic and pituitary development we used Nkx2.1-cre and Prop1-cre to delete Six3 in mice. The Nkx2.1-cre, Six3flox/flox embryos had no evidence of infundibulum evagination or expression of Fgf10 or Tcf7l2 at e11.5. The oral ectoderm invaginated in mutants, but no definitive Rathke’s pouch formed. There was no evidence of Lhx3 expression and only trace amounts of Pitx1, indicating that pituitary induction failed due to the lack of Six3 in the developing hypothalamus. Similarly, disruption of Six3 expression in Rathke’s pouch using Prop1-cre ablated pituitary development. Together, these data reveal essential roles of Six3 in both the neural and oral ectoderm for hypothalamic and pituitary development, respectively. Heterozygous loss of function variants in SIX3 could be a contributor to multiple pituitary hormone deficiencies in children, especially if there are associated craniofacial abnormalities.

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Contribution of LHX4 Mutations to Pituitary Deficits in a Cohort of 417 Unrelated Patients

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jc.2016-3158 ◽

2016 ◽

Vol 102 (1) ◽

pp. 290-301 ◽

Cited By ~ 6

Author(s):

Enzo Cohen ◽

Mohamad Maghnie ◽

Nathalie Collot ◽

Juliane Leger ◽

Florence Dastot ◽

...

Keyword(s):

Sella Turcica ◽

Hormone Deficiency ◽

Pituitary Hormone ◽

Incomplete Penetrance ◽

Posterior Pituitary ◽

Variable Expressivity ◽

Functional Studies ◽

Ectopic Posterior Pituitary ◽

Congenital Hypopituitarism

Abstract Context: LHX4 encodes a LIM-homeodomain transcription factor that is implicated in early pituitary development. In humans, only 13 heterozygous LHX4 mutations have been associated with congenital hypopituitarism. Objective: The aims of this study were to evaluate the prevalence of LHX4 mutations in patients with hypopituitarism, to define the associated phenotypes, and to characterize the functional impact of the identified variants and the respective role of the 2 LIM domains of LHX4. Design and Patients: We screened 417 unrelated patients with isolated growth hormone deficiency or combined pituitary hormone deficiency associated with ectopic posterior pituitary and/or sella turcica anomalies for LHX4 mutations (Sanger sequencing). In vitro studies were performed to assess the functional consequences of the identified variants. Results: We identified 7 heterozygous variations, including p.(Tyr131*), p.(Arg48Thrfs*104), c.606+1G>T, p.Arg65Val, p.Thr163Pro, p.Arg221Gln, and p.Arg235Gln), that were associated with variable expressivity; 5 of the 7 were also associated with incomplete penetrance. The p.(Tyr131*), p.(Arg48Thrfs*104), p.Ala65Val, p.Thr163Pro, and p.Arg221Gln LHX4 variants are unable to transactivate the POU1F1 and GH promoters. As suggested by transactivation, subcellular localization, and protein-protein interaction studies, p.Arg235Gln is probably a rare polymorphism. Coimmunoprecipitation studies identified LHX3 as a potential protein partner of LHX4. As revealed by functional studies of LIM-defective recombinant LHX4 proteins, the LIM1 and LIM2 domains are not redundant. Conclusion: This study, performed in the largest cohort of patients screened so far for LHX4 mutations, describes 6 disease-causing mutations that are responsible for congenital hypopituitarism. LHX4 mutations were found to be associated with variable expressivity, and most of them with incomplete penetrance; their contribution to pituitary deficits that are associated with an ectopic posterior pituitary and/or a sella turcica defect is ∼1.4% in the 417 probands tested.

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miR-16-5p Promotes Erythroid Maturation of Erythroleukemia Cells by Regulating Ribosome Biogenesis

Pharmaceuticals ◽

10.3390/ph14020137 ◽

2021 ◽

Vol 14 (2) ◽

pp. 137

Author(s):

Christos I. Papagiannopoulos ◽

Nikoleta F. Theodoroula ◽

Ioannis S. Vizirianakis

Keyword(s):

Ribosomal Proteins ◽

Ribosome Biogenesis ◽

Cultured Cells ◽

Erythroid Differentiation ◽

Underlying Mechanism ◽

Loss Of Function ◽

Functional Studies ◽

Differentiated Cells ◽

Erythroleukemia Cells ◽

Murine Erythroleukemia

miRNAs constitute a class of non-coding RNA that act as powerful epigenetic regulators in animal and plant cells. In order to identify putative tumor-suppressor miRNAs we profiled the expression of various miRNAs during differentiation of erythroleukemia cells. RNA was purified before and after differentiation induction and subjected to quantitative RT-PCR. The majority of the miRNAs tested were found upregulated in differentiated cells with miR-16-5p showing the most significant increase. Functional studies using gain- and loss-of-function constructs proposed that miR-16-5p has a role in promoting the erythroid differentiation program of murine erythroleukemia (MEL) cells. In order to identify the underlying mechanism of action, we utilized bioinformatic in-silico platforms that incorporate predictions for the genes targeted by miR-16-5p. Interestingly, ribosome constituents, as well as ribosome biogenesis factors, were overrepresented among the miR-16-5p predicted gene targets. Accordingly, biochemical experiments showed that, indeed, miR-16-5p could modulate the levels of independent ribosomal proteins, and the overall ribosomal levels in cultured cells. In conclusion, miR-16-5p is identified as a differentiation-promoting agent in erythroleukemia cells, demonstrating antiproliferative activity, likely as a result of its ability to target the ribosomal machinery and restore any imbalanced activity imposed by the malignancy and the blockade of differentiation.

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SIAE Rare Variants in Juvenile Idiopathic Arthritis and Primary Antibody Deficiencies

Journal of Immunology Research ◽

10.1155/2017/1514294 ◽

2017 ◽

Vol 2017 ◽

pp. 1-11 ◽

Cited By ~ 1

Author(s):

Eirini Sevdali ◽

Elena Tsitsami ◽

Maria Tsinti ◽

Evangelia Farmaki ◽

Efimia Papadopoulou-Alataki ◽

...

Keyword(s):

Juvenile Idiopathic Arthritis ◽

Sialic Acid ◽

Cell Activation ◽

Rare Variants ◽

Primary Antibody ◽

Healthy Children ◽

B Cell Activation ◽

Loss Of Function ◽

Primary Antibody Deficiencies ◽

Sialic Acid Binding

Sialic acid acetylesterase (SIAE) deficiency was suggested to lower the levels of ligands for sialic acid-binding immunoglobulin-like receptors, decreasing the threshold for B-cell activation. In humans, studies of rare heterozygous loss-of-function mutations in SIAE gene in common autoimmune diseases, including juvenile idiopathic arthritis (JIA), yielded inconsistent results. Considering the distinct pathogenesis of the two main subtypes of JIA, autoinflammatory systemic (sJIA) and autoimmune oligo/polyarticular (aJIA), and a predisposition to autoimmunity displayed by patients and families with primary antibody deficiencies (PADs), the aim of our study was to analyze whether SIAE rare variants are associated with both the phenotype of JIA and the autoimmunity risk in families with PADs. A cohort of 69 patients with JIA, 117 healthy children, 54 patients, and family members with PADs were enrolled in the study. Three novel SIAE variants (p.Q343P, p.Y495X, and c.1320+33T>C) were found only in patients with aJIA but interestingly also in their healthy relatives without autoimmunity, while none of PAD patients or their relatives carried SIAE defects. Our results show that SIAE rare variants are not causative of autoimmunity as single defects.

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Rare variants in KDR, encoding VEGF Receptor 2, are associated with tetralogy of Fallot

Genetics in Medicine ◽

10.1038/s41436-021-01212-y ◽

2021 ◽

Author(s):

Doris Škorić-Milosavljević ◽

Najim Lahrouchi ◽

Fernanda M. Bosada ◽

Gregor Dombrowsky ◽

Simon G. Williams ◽

...

Keyword(s):

Exome Sequencing ◽

Tetralogy Of Fallot ◽

Large Scale ◽

Rare Variants ◽

Growth Factor Receptor ◽

Vegf Receptor ◽

Loss Of Function ◽

Endothelial Growth Factor

Abstract Purpose Rare genetic variants in KDR, encoding the vascular endothelial growth factor receptor 2 (VEGFR2), have been reported in patients with tetralogy of Fallot (TOF). However, their role in disease causality and pathogenesis remains unclear. Methods We conducted exome sequencing in a familial case of TOF and large-scale genetic studies, including burden testing, in >1,500 patients with TOF. We studied gene-targeted mice and conducted cell-based assays to explore the role of KDR genetic variation in the etiology of TOF. Results Exome sequencing in a family with two siblings affected by TOF revealed biallelic missense variants in KDR. Studies in knock-in mice and in HEK 293T cells identified embryonic lethality for one variant when occurring in the homozygous state, and a significantly reduced VEGFR2 phosphorylation for both variants. Rare variant burden analysis conducted in a set of 1,569 patients of European descent with TOF identified a 46-fold enrichment of protein-truncating variants (PTVs) in TOF cases compared to controls (P = 7 × 10-11). Conclusion Rare KDR variants, in particular PTVs, strongly associate with TOF, likely in the setting of different inheritance patterns. Supported by genetic and in vivo and in vitro functional analysis, we propose loss-of-function of VEGFR2 as one of the mechanisms involved in the pathogenesis of TOF.

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The Mutational Landscape of PTK7 in Congenital Scoliosis and Adolescent Idiopathic Scoliosis

Genes ◽

10.3390/genes12111791 ◽

2021 ◽

Vol 12 (11) ◽

pp. 1791

Author(s):

Zhe Su ◽

Yang Yang ◽

Shengru Wang ◽

Sen Zhao ◽

Hengqiang Zhao ◽

...

Keyword(s):

Adolescent Idiopathic Scoliosis ◽

Idiopathic Scoliosis ◽

Protein Expression ◽

Rare Variants ◽

Congenital Scoliosis ◽

Loss Of Function ◽

Wild Type ◽

Cellular Location ◽

Mutational Landscape

Depletion of ptk7 is associated with both congenital scoliosis (CS) and adolescent idiopathic scoliosis (AIS) in zebrafish models. However, only one human variant of PTK7 has been reported previously in a patient with AIS. In this study, we systemically investigated the variant landscape of PTK7 in 583 patients with CS and 302 patients with AIS from the Deciphering Disorders Involving Scoliosis and COmorbidities (DISCO) study. We identified a total of four rare variants in CS and four variants in AIS, including one protein truncating variant (c.464_465delAC) in a patient with CS. We then explored the effects of these variants on protein expression and sub-cellular location. We confirmed that the c.464_465delAC variant causes loss-of-function (LoF) of PTK7. In addition, the c.353C>T and c.2290G>A variants identified in two patients with AIS led to reduced protein expression of PTK7 as compared to that of the wild type. In conclusion, LoF and hypomorphic variants are associated with CS and AIS, respectively.

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Anatomical, Physiological, and Functional Heterogeneity of the Dorsal Raphe Serotonin System

10.1101/257378 ◽

2018 ◽

Cited By ~ 3

Author(s):

Jing Ren ◽

Drew Friedmann ◽

Jing Xiong ◽

Cindy D. Liu ◽

Katherine E. DeLoach ◽

...

Keyword(s):

Frontal Cortex ◽

Glutamate Transporter ◽

Dorsal Raphe ◽

Loss Of Function ◽

Homogeneous Population ◽

Functional Studies ◽

Serotonin System ◽

Distinct Cell ◽

Serotonin Neurons ◽

Dorsal Raphé

SummaryThe dorsal raphe (DR) constitutes a major serotonergic input to the forebrain, and modulates diverse functions and brain states including mood, anxiety, and sensory and motor functions. Most functional studies to date have treated DR serotonin neurons as a single, homogeneous population. Using viral-genetic methods, we found that subcortical-vs. cortical-projecting serotonin neurons have distinct cell body distributions within the DR and different degrees of coexpressing a vesicular glutamate transporter. Further, the amygdala-and frontal cortex-projecting DR serotonin neurons have largely complementary whole-brain collateralization patterns, receive biased inputs from presynaptic partners, and exhibit opposite responses to aversive stimuli. Gain-and loss-of-function experiments suggest that amygdala-projecting DR serotonin neurons promote anxiety-like behavior, whereas frontal cortex-projecting neurons promote active coping in face of challenge. These results provide compelling evidence that the DR serotonin system contains parallel sub-systems that differ in input and output connectivity, physiological response properties, and behavioral functions.

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Ras controls growth, survival and differentiation in the Drosophila eye by different thresholds of MAP kinase activity

Development ◽

10.1242/dev.128.9.1687 ◽

2001 ◽

Vol 128 (9) ◽

pp. 1687-1696 ◽

Cited By ~ 3

Author(s):

K. Halfar ◽

C. Rommel ◽

H. Stocker ◽

E. Hafen

Keyword(s):

Cell Cycle ◽

Cell Cycle Progression ◽

Kinase Activity ◽

Photoreceptor Cells ◽

Loss Of Function ◽

Cellular Functions ◽

Partial Loss ◽

Cycle Progression ◽

Mapk Activity ◽

Dividing Cells

Ras mediates a plethora of cellular functions during development. In the developing eye of Drosophila, Ras performs three temporally separate functions. In dividing cells, it is required for growth but is not essential for cell cycle progression. In postmitotic cells, it promotes survival and subsequent differentiation of ommatidial cells. In the present paper, we have analyzed the different roles of Ras during eye development by using molecularly defined complete and partial loss-of-function mutations of Ras. We show that the three different functions of Ras are mediated by distinct thresholds of MAPK activity. Low MAPK activity prolongs cell survival and permits differentiation of R8 photoreceptor cells while high or persistent MAPK activity is sufficient to precociously induce R1-R7 photoreceptor differentiation in dividing cells.

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Analysis of exome-sequenced UK Biobank subjects implicates genes affecting risk of hyperlipidaemia

10.1101/2020.07.09.20150334 ◽

2020 ◽

Author(s):

David Curtis

Keyword(s):

Rare Variants ◽

Sequence Data ◽

Lipid Lowering ◽

P Value ◽

Data Sets ◽

Uk Biobank ◽

Functional Studies ◽

Exome Sequence Data ◽

Rare Genetic Variants ◽

The Uk

Rare genetic variants in LDLR, APOB and PCSK9 are known causes of familial hypercholesterolaemia and it is expected that rare variants in other genes will also have effects on hyperlipidaemia risk although such genes remain to be identified. The UK Biobank consists of a sample of 500,000 volunteers and exome sequence data is available for 50,000 of them. 11,490 of these were classified as hyperlipidaemia cases on the basis of having a relevant diagnosis recorded and/or taking lipid-lowering medication while the remaining 38,463 were treated as controls. Variants in each gene were assigned weights according to rarity and predicted impact and overall weighted burden scores were compared between cases and controls, including population principal components as covariates. One biologically plausible gene, HUWE1, produced statistically significant evidence for association after correction for testing 22,028 genes with a signed log10 p value (SLP) of -6.15, suggesting a protective effect of variants in this gene. Other genes with uncorrected p<0.001 are arguably also of interest, including LDLR (SLP=3.67), RBP2 (SLP=3.14), NPFFR1 (SLP=3.02) and ACOT9 (SLP=-3.19). Gene set analysis indicated that rare variants in genes involved in metabolism and energy can influence hyperlipidaemia risk. Overall, the results provide some leads which might be followed up with functional studies and which could be tested in additional data sets as these become available. This research has been conducted using the UK Biobank Resource.

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