Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.10.1 (ERK)
 95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

GnRH embryonic neuronal fate is determined by discreet spatio-temporal expression patterns and interactions of axonal guidance and cell adhesion molecules and extracellular matrix proteins. Expression of several transcription factors, locally derived growth factors and neurotransmitters influence GnRH ontogeny and rostral forebrain specification. In man, disrupted GnRH neuronal ontogeny can be caused by several monogenic disorders leading to isolated hypogonadotrophic hypogonadism (IHH); these include mutations within KAL-1, GnRH-R, and FGFR1. Mutations in KAL-1 and its encoded protein anosmin-1, causes X-linked Kallmann's syndrome (XKS) characterized by IHH, anosmia, synkinesis, and unilateral renal agenesis. Anosmin-1 has an obligate functional interaction with membrane associated heparan sulphate proteoglycans (HSPG) and FGFR-1 (KAL-2) whose mutations lead to the autosomal dominant form of KS (AKS). FGFR1 and anosmin-1 may interact via a HSPG dependent mechanism raising the possibility of interaction between two single gene defects cause similar phenotypic abnormalities.
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PMID:Ontogeny of GnRH and olfactory neuronal systems in man: novel insights from the investigation of inherited forms of Kallmann's syndrome. 1557 57

Idiopathic Hypogonadotropic Hypogonadism (IHH), a syndrome of GnRH deficiency, is characterized by varying degrees of sexual development disruption. When associated with anosmia, it is termed Kallmann Syndrome (KS). Although it was identified as a hereditary disorder over half a century ago, only during the last two decades have specific putative IHH genes been revealed, including: KAL1, GnRHR, FGFR1, GPR54, PROK2, PROKR2, FGF8, CHD7, TAC3 and TAC3R. Human mutations have shed light on the molecular control of GnRH neuronal embryogenesis and have elucidated elements critical in sexual development. Furthermore, the newly proposed oligogenic model has challenged the dogma of IHH being a single gene disorder and has heightened appreciation for the functional overlap of distinct signaling systems. This review offers an historical perspective to gene discoveries in IHH, genotype-phenotype correlations, and finally, discussion of the evolving complexity of the new IHH genetic model, no longer simply characterized by Mendelian inheritance.
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PMID:The genetics of idiopathic hypogonadotropic hypogonadism:unraveling the biology of human sexual development. 1939 25

The Kallmann syndrome (KS) combines hypogonadotropic hypogonadism (HH) with anosmia. This is a clinically and genetically heterogeneous disease. KAL1, encoding the extracellular glycoprotein anosmin-1, is responsible for the X chromosome-linked recessive form of the disease (KAL1). Mutations in FGFR1 or FGF8, encoding fibroblast growth factor receptor-1 and fibroblast growth factor-8, respectively, underlie an autosomal dominant form with incomplete penetrance (KAL2). Mutations in PROKR2 and PROK2, encoding prokineticin receptor-2 and prokineticin-2, have been found in heterozygous, homozygous, and compound heterozygous states. These two genes are likely to be involved both in autosomal recessive monogenic (KAL3) and digenic/oligogenic KS transmission modes. Mutations in any of the above-mentioned KS genes have been found in less than 30% of the KS patients, which indicates that other genes involved in the disease remain to be discovered. Notably, KS may also be part of pleiotropic developmental diseases including CHARGE syndrome; this disease results in most cases from neomutations in CHD7 that encodes a chromodomain helicase DNA-binding protein.
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PMID:Clinical genetics of Kallmann syndrome. 2036 62

The gene for X-linked Kallmann's syndrome (KAL-1, encoding anosmin-1) was cloned in 1991. Over a decade elapsed before autosomal forms of KS and most of other genetic forms of isolated hypogonadotrophic hypogonadism (IHH) became characterized, and the genetic diversity of these disorders fully appreciated. Although KAL-1 mutations appear to cause a more severe reproductive phenotype than other IHH genes, the biology of this multidomain extracellular matrix protein has only been partially characterized. Initial studies suggested a central role of anosmin-1, in GnRH neuron ontogeny - specifically in GnRH neuronal migration from the cribriform plate area into the brain - as well as in olfactory bulb development. Anosmin-1 is expressed extracellularly, with high affinity binding to cell membrane heparan sulphate proteoglycans. It is expressed in the outer layers of the developing olfactory bulb, the neuroretina, the cerebellum, spinal cord and developing kidney. Recent observations have demonstrated an anosmin-1 heparan sulphate dependent functional interaction with the product of the autosomal dominant KAL-2 (FGFR1: anosmin-2) gene, thereby modulating FGFR1 signalling. Although these genes are frequently co-expressed in developing tissues, this may not represent the sole mode of action of anosmin-1, and FGFR1 independent actions of the protein have also been identified. Structural and in vitro functional studies have shown that anosmin-1 may have complex biological actions. Anosmin-1 interactions with FGFR1 have however been best characterized and represent the dominant focus of this chapter.
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PMID:X-linked GnRH deficiency: role of KAL-1 mutations in GnRH deficiency. 2149 78

Kallmann Syndrome (KS) is a genetic disease of embryonic development which is characterized by the association of hypogonadotropic hypogonadism (HH) due to a deficit of the gonadotropin-releasing hormone (GnRH) and a hypo/anosmia (including a hypoplasia of the nasal sulcus and agenesis of the olfactory bulbs). Even though it is a genotypically and phenotypically heterogeneous clinical disease, there are some key genes related to KS (KAL1, FGFR1 (KAL2), GNRHR, KISSR1 (GPR54), GNRH1, NELF and PROK2). The aim of this study was to present a case report of a genetic diagnosis of KS linked to the presence of mutations in the FGFR1 (fibroblast growth factor receptor 1, also known as KAL2) gene. This diagnosis was made in a 44-year old female affected by a hypogonadism for which she had received intermittent treatment until she was 30 years old based on the patient's own decision. The molecular analysis of FGFR1 identified the mutation c. 246_247delAG (p.T82Xfs110) in heterozygosis on exon 3 of the KAL2 gene. This is the first report of this mutation related to idiopathic hypogonadotrophic hypogonadism (IHH).
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PMID:Genetic diagnosis of idiopathic hypogonadotrophic hypogonadism: a new point mutation in the KAL2 gene. 2477 28

Fibroblast growth factor 8 (FGF8) is a potent morphogen that regulates the ontogenesis of gonadotropin-releasing hormone (GnRH) neurons, which control the hypothalamus-pituitary-gonadal (HPG) axis, and therefore reproductive success. Indeed, FGF8 and FGFR1 deficiency severely compromises vertebrate reproduction in mice and humans and is associated with Kallmann Syndrome (KS), a congenital disease characterized by hypogonadotropic hypogonadism associated with anosmia. Our laboratory demonstrated that FGF8 signaling through FGFR1, both of which are KS-related genes, is necessary for proper GnRH neuron development in mice and humans. Here, we investigated the possibility that non-genetic factors, such as the epigenome, may contribute to KS onset. For this purpose, we developed an embryonic explant model, utilizing the mouse olfactory placode (OP), the birthplace of GnRH neurons. We show that TET1, which converts 5-methylcytosine residues (5mC) to 5-hydroxymethylated cytosines (5hmC), controls transcription of Fgf8 during GnRH neuron ontogenesis. Through MeDIP and ChIP RT-qPCR we found that TET1 bound to specific CpG islands on the Fgf8 promoter. We found that the temporal expression of Fgf8 correlates with not only TET1 binding, but also with 5hmC enrichment. siRNA knockdown of Tet1 reduced Fgf8 and Fgfr1 mRNA expression. During this time period, Fgf8 also switched histone status, most likely via recruitment of EZH2, a major component of the polycomb repressor complex-2 (PRC2) at E13.5. Together, these studies underscore the significance of epigenetics and chromatin modifications to temporally regulated genes involved in KS.
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PMID:TET1 regulates fibroblast growth factor 8 transcription in gonadotropin releasing hormone neurons. 3136 80