Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0025362 (mental retardation)
15,878 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We describe three families with X-linked mental retardation, two with a deletion of a single amino acid and one with a missense mutation in the proximal domain of the RSK2(RPS6KA3) (ribosomal protein S6 kinase, 90 kDa, polypeptide 3) protein similar to mutations found in Coffin-Lowry syndrome (CLS). In two families, the clinical diagnosis had been nonsyndromic X-linked mental retardation. In the third family, although CLS had been suspected, the clinical features were atypical and the degree of intellectual disability much less than expected. These families show that strict reliance on classical clinical criteria for mutation testing may result in a missed diagnosis. A less targeted screening approach to mutation testing is advocated.
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PMID:Mutations in the RSK2(RPS6KA3) gene cause Coffin-Lowry syndrome and nonsyndromic X-linked mental retardation. 1710 Sep 96

Coffin-Lowry syndrome (CLS) is a rare form of X-linked mental retardation caused by mutations of the RSK2 gene, associated with cognitive impairment and skeletal malformations. We conducted the first morphometric study of CLS brain morphology by comparing brain volumes from two CLS families with healthy controls. Individuals with CLS consistently showed markedly reduced total brain volume. Cerebellum and hippocampus volumes were particularly impacted by CLS and may be associated with specific interfamilial RSK2 mutations. We provide preliminary evidence that the magnitude of hippocampus volume deviation from that of controls may predict general cognitive outcome in CLS.
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PMID:Altered neurodevelopment associated with mutations of RSK2: a morphometric MRI study of Coffin-Lowry syndrome. 1731 37

Duplications of the short arm of the X chromosome in male patients are rare. We report on the clinical features of mentally retarded patients in two families with different interstitial duplications of Xp and their characterization by tiling path array comparative genomic hybridization (array CGH). In Family A, we detected a duplication of 9.3 Mb in Xp11p21 in a male with severe mental retardation [karyotype 46,XY,dup(X)(p11.3p21.1)] and his healthy mother. The clinical features of this patient--severe mental retardation, obesity, macrocephaly--are in accordance with those of a previously reported patient with a similar duplication. In Family B, a duplication of 8.5 Mb was diagnosed in Xp22 in three male patients with mental retardation [karyotype 46,XY,dup(X)(p22.11p22.2)] and two healthy females. Characterization of the duplications by array CGH enabled the identification of the genes within these intervals. These comprise known mental retardation genes such as MAOA, NDP, TM4SF2, NDP, RSK2, and CDKL5. Duplication of MAOA will be discussed as a possible cause of obesity.
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PMID:Characterization of interstitial Xp duplications in two families by tiling path array CGH. 1807 17

The Coffin-Lowry syndrome, a rare syndromic form of X-linked mental retardation, is caused by loss-of-function mutations in the hRSK2 (RPS6KA3) gene. To further investigate RSK2 (90-kDa ribosomal S6 kinase) implication in cognitive processes, a mrsk2_KO mouse has previously been generated as an animal model of Coffin-Lowry syndrome. The aim of the present study was to identify possible neurochemical dysregulation associated with the behavioral and morphological abnormalities exhibited by mrsk2_KO mice. A cortical dopamine level increase was found in mrsk2_KO mice that was accompanied by an over-expression of dopamine receptor of type 2 and the dopamine transporter. We also detected an increase of total and phosphorylated extracellular regulated kinase that may be responsible for the increased level of tyrosine hydroxylase phosphorylation also observed. By taking into consideration previously reported data, our results strongly suggest that the dopaminergic dysregulation in mrsk2_KO mice may be caused, at least in part, by tyrosine hydroxylase hyperactivity. This cortical hyperdopaminergia may explain some non-cognitive but also cognitive alterations exhibited by mrsk2_KO mice.
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PMID:Dopaminergic system dysregulation in the mrsk2_KO mouse, an animal model of the Coffin-Lowry syndrome. 1882 70

X-linked alpha-thalassemia/mental retardation syndrome (ATR-X syndrome, OMIM #301040) is one of the syndromes associated with abnormal epigenetic gene regulation, including ICF(DNMT3B), Rett (MECP2), Rubinstein-Taybi (CBP), Coffin-Lowry (RSK2), and Sotos (NSD1) syndromes. It is a syndromic form of X-linked mental retardation, which affects males and is characterized by profound mental retardation, mild HbH disease (alpha-thalassemia), facial dysmorphism, skeletal abnormalities, and autistic behavior. ATR-X syndrome is caused by a mutation in the ATRX gene on the X chromosome (Xq13), which encodes ATRX protein, belonging to the SNF2 family of chromatin-remodeling proteins. The protein has two functionally important domains: an ADD (ATRX-DNMT3-DNMT3L) domain at the N-terminus, and chromatin-remodeling domain in the C-terminal half, where the ATRX gene mutations of most ATR-X patients reside. Perturbation in DNA methylation in the rDNA genes was repored in ATR-X patients, and ATRX protein is presumed to be involved in the establishment and maintenance of DNA methylation. Based on its various clinical phenotypes, the expressions of many genes, including alpha globin genes, seem to be abnormally regulated in ATR-X patients. However, the precise mechanism involving ATRX protein remains to be elucidated. Epigenetics can link environmental and genetic causes of many pathological conditions. The genes, which are abnormally regulated by a perturbed epigenetic mechanism, are, in themselves, structurally normal, and the elucidation of their mechanism may lead to the development of appropriate therapy.
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PMID:[X-linked alpha-thalassemia/mental retardation syndrome]. 1948 41

Coffin-Lowry syndrome (CLS) is a syndromic form of X-linked mental retardation, which is characterized in male patients by psychomotor and growth retardation and various skeletal anomalies. Typical facial changes and specific clinical and radiological signs in the hand are useful aids in the diagnosis. CLS is caused by mutations in the RPS6KA3 gene located at Xp22.2, which encodes RSK2, a growth-factor-regulated protein kinase. RPS6KA3 mutations are extremely heterogeneous and lead to loss of phosphotransferase activity in the RSK2 kinase, most often because of premature termination of translation.
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PMID:Coffin-Lowry syndrome. 1988

Coffin-Lowry syndrome (CLS) is a syndromic form of X-linked mental retardation, characterized in male patients by psychomotor and growth retardation and various skeletal anomalies. CLS is caused by mutations in the RPS6KA3 gene, which encodes RSK2, a growth factor-regulated protein kinase. Cognitive deficiencies in CLS patients are prominent, but markedly variable in severity, even between siblings. However, the vast majority of patients are severely affected, with mental retardation ranging from moderate to profound. We used a RSK2-KO mouse model that shows no obvious brain abnormalities at the anatomical and histological levels to study the function of RSK2 in neurosecretion. Behavioral studies revealed normal motor coordination, but a profound retardation in spatial learning and a deficit in long-term spatial memory, providing evidence that RSK2 plays similar roles in mental functioning both in mice and human. We found that associative LTP at cortical inputs to the lateral amygdala was blocked in Rsk2 KO mice. Using an RNA interference rescue strategy in PC12 cells, we were able to demonstrate that RSK2 regulates catecholamine release through the phosphorylation of PLD. These results provide the first molecular evidence that RSK2 could regulate neurotransmitter release by activating PLD production of lipids required for exocytosis.
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PMID:The Coffin-Lowry syndrome-associated protein RSK2 and neurosecretion. 2106 Nov 66

Coffin-Lowry syndrome (CLS) is a syndromic form of mental retardation caused by loss of function mutations in the X-linked RPS6KA3 gene, which encodes RSK2, a serine/threonine kinase acting in the MAPK/ERK pathway. The mouse invalidated for the Rps6ka3 (Rsk2-KO) gene displays learning and long-term spatial memory deficits. In the current study, we compared hippocampal gene expression profiles from Rsk2-KO and normal littermate mice to identify changes in molecular pathways. Differential expression was observed for 100 genes encoding proteins acting in various biological pathways, including cell growth and proliferation, cell death and higher brain function. The twofold up-regulated gene (Gria2) was of particular interest because it encodes the subunit GLUR2 of the AMPA glutamate receptor. AMPA receptors mediate most fast excitatory synaptic transmission in the central nervous system. We provide evidence that in the hippocampus of Rsk2-KO mice, expression of GLUR2 at the mRNA and at the protein levels is significantly increased, whereas basal AMPA receptor-mediated transmission in the hippocampus of Rsk2-KO mice is significantly decreased. This is the first time that such deregulations have been demonstrated in the mouse model of the Coffin-Lowry syndrome. Our findings suggest that a defect in AMPA neurotransmission and plasticity contribute to mental retardation in CLS patients.
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PMID:Transcriptome profile reveals AMPA receptor dysfunction in the hippocampus of the Rsk2-knockout mice, an animal model of Coffin-Lowry syndrome. 2111 50

Coffin-Lowry syndrome is a syndromic form of mental retardation caused by mutations of the Rps6ka3 gene encoding ribosomal s6 kinase (RSK)2. RSK2 belongs to a family containing four members in mammals: RSK1-4. RSKs are serine/threonine kinases and cytosolic substrates of extracellular signal-regulated kinase (ERK) in the Ras/MAPK signaling pathway. RSK2 is highly expressed in the hippocampus, and mrsk2_KO mice display spatial learning and memory impairment. In the present study, we provide evidence of abnormally increased phosphorylation of ERK1/2 in the hippocampus of mrsk2_KO mice. Further studies based on cultured hippocampal neurons revealed that glutamate activates ERK1/2 and RSKs, and confirmed a stronger activation of ERK1/2 in mrsk2_KO neurons than in WT cells. We, thus, provide further evidence that RSK2 exerts a feedback inhibitory effect on the ERK1/2 pathway. We also observed a transient sequestration of P-ERK1/2 in the cytoplasm upon glutamate stimulation. In addition, the transcription factors cAMP response element binding and Ets LiKe gene1 show over-activation in RSK2-deficient neurons. Finally, c-Fos, Zif268 and Arc were significantly over-expressed in mrsk2_KO neurons upon glutamate stimulation. Importantly, the increased phosphorylation of other RSK family members observed in mutant neurons was unable to compensate for RSK2 deficiency. This aberrant ERK1/2 signaling can influence various neuronal functions, and thus play a significant role in cognitive dysfunction in mrsk2_KO mice and in the Coffin-Lowry syndrome.
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PMID:Altered ERK/MAPK signaling in the hippocampus of the mrsk2_KO mouse model of Coffin-Lowry syndrome. 2183 83

More than 80 human X-linked genes have been associated with mental retardation and deficits in learning and memory. However, most of the identified mutations induce limited morphological alterations in brain organization and the molecular bases underlying neuronal clinical features remain elusive. We show here that neurons cultured from mice lacking ribosomal S6 kinase 2 (Rsk2), a model for the Coffin-Lowry syndrome (CLS), exhibit a significant delay in growth in a similar way to that shown by neurons cultured from phospholipase D1 (Pld1) knock-out mice. We found that gene silencing of Pld1 or Rsk2 as well as acute pharmacological inhibition of PLD1 or RSK2 in PC12 cells strongly impaired neuronal growth factor (NGF)-induced neurite outgrowth. Expression of a phosphomimetic PLD1 mutant rescued the inhibition of neurite outgrowth in PC12 cells silenced for RSK2, revealing that PLD1 is a major target for RSK2 in neurite formation. NGF-triggered RSK2-dependent phosphorylation of PLD1 led to its activation and the synthesis of phosphatidic acid at sites of neurite growth. Additionally, total internal reflection fluorescence microscopy experiments revealed that RSK2 and PLD1 positively control fusion of tetanus neurotoxin insensitive vesicle-associated membrane protein (TiVAMP)/VAMP-7 vesicles at sites of neurite outgrowth. We propose that the loss of function mutations in RSK2 that leads to CLS and neuronal deficits are related to defects in neuronal growth due to impaired RSK2-dependent PLD1 activity resulting in a reduced vesicle fusion rate and membrane supply.
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PMID:The Coffin-Lowry syndrome-associated protein RSK2 regulates neurite outgrowth through phosphorylation of phospholipase D1 (PLD1) and synthesis of phosphatidic acid. 2433 13


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