SEDLIN Forms Homodimers: Characterisation of SEDLIN Mutations and Their Interactions with Transcription Factors MBP1, PITX1 and SF1

BACKGROUND: SEDLIN, a 140 amino acid subunit of the Transport Protein Particle (TRAPP) complex, is ubiquitously expressed and interacts with the transcription factors c-myc promoter-binding protein 1 (MBP1), pituitary homeobox 1 (PITX1) and steroidogenic factor 1 (SF1). SEDLIN mutations cause X-linked spondyloepiphyseal dysplasia tarda (SEDT). METHODOLOGY/PRINCIPAL FINDINGS: We investigated the effects of 4 missense (Asp47Tyr, Ser73Leu, Phe83Ser and Val130Asp) and the most C-terminal nonsense (Gln131Stop) SEDT-associated mutations on interactions with MBP1, PITX1 and SF1 by expression in COS7 cells. Wild-type SEDLIN was present in the cytoplasm and nucleus and interacted with MBP1, PITX1 and SF1; the SEDLIN mutations did not alter these subcellular localizations or the interactions. However, SEDLIN was found to homodimerize, and the formation of dimers between wild-type and mutant SEDLIN would mask a loss in these interactions. A mammalian SEDLIN null cell-line is not available, and the interactions between SEDLIN and the transcription factors were therefore investigated in yeast, which does not endogenously express SEDLIN. This revealed that all the SEDT mutations, except Asp47Tyr, lead to a loss of interaction with MBP1, PITX1 and SF1. Three-dimensional modelling studies of SEDLIN revealed that Asp47 resides on the surface whereas all the other mutant residues lie within the hydrophobic core of the protein, and hence are likely to affect the correct folding of SEDLIN and thereby disrupt protein-protein interactions. CONCLUSIONS/SIGNIFICANCE: Our studies demonstrate that SEDLIN is present in the nucleus, forms homodimers and that SEDT-associated mutations cause a loss of interaction with the transcription factors MBP1, PITX1 and SF1

Comparative genomics of the eukaryotes

A comparative analysis of the genomes of Drosophila melanogaster, Caenorhabditis elegans, and Saccharomyces cerevisiae-and the proteins they are predicted to encode-was undertaken in the context of cellular, developmental, and evolutionary processes. The nonredundant protein sets of flies and worms are similar in size and are only twice that of yeast, but different gene families are expanded in each genome, and the multidomain proteins and signaling pathways of the fly and worm are far more complex than those of yeast. The fly has orthologs to 177 of the 289 human disease genes examined and provides the foundation for rapid analysis of some of the basic processes involved in human disease

Major Depressive Disorder With Subthreshold Bipolarity in the National Comorbidity Survey Replication

Objective: There is growing clinical and epidemiologic evidence that major mood disorders form a spectrum from major depressive disorder to pure mania. The authors examined the prevalence and clinical correlates of major depressive disorder with subthreshold bipolarity compared with pure major depressive disorder in the National Comorbidity Survey Replication (NCS-R).Method: The NCS-R is a nationally representative face-to-face household survey of the U.S. population conducted between February 2001, and April 2003. Lifetime history of mood disorders, symptoms, and clinical indicators of severity were collected using version 3.0 of the World Health Organization's Composite International Diagnostic Interview.Results: Nearly 40% of study participants with a history of major depressive disorder had a history of subthreshold hypo-mania. This subgroup had a younger age at onset, more episodes of depression, and higher rates of comorbidity than those without a history of hypomania and lower levels of clinical severity than those with bipolar II disorder.Conclusions: These findings demonstrate heterogeneity in major depressive disorder and support the validity of inclusion of subthreshold mania in the diagnostic classification. The broadening of criteria for bipolar disorder would have important implications for research and clinical practice

Mutational analysis of the 5-HT1B and 5-HT1E serotonin receptor genes in three datasets with schizophrenia.

We have investigated two serotonin receptor genes located in the 6q13-q26 area: the 5-ht1e and the 5-ht1b genes. Both receptors belong to the G-protein superfamily and contain the characteristic seven transmembrane regions, are localized in the brain, are intronless, and are negatively coupled to adenylyl cyclase. Both receptors have been studied by mutational analysis techniques by at least one other group [Shimron-Abarbanell et al., 1995; Nothen et al., 1994], in both cases association with schizophrenia was found negative. Therefore, we consider our mutational analysis work a "second pass." For the study of association, we have employed three clinical data sets (n = 180 families) that have supported the existence of a susceptibility gene for schizophrenia in 6q13-26 [Martinez et al., submitted]. We have found in a screening of 97 unrelated individuals (mostly Caucasians) the following new polymorphisms: 1) 5-ht1b. Silent DNA variations: C129T, C705T; missense DNA variations: C662A Thr-Asn, A1099G Ile-Val, G1120AGlu-Lys. We have also detected a variation previously reported by Nothen et al. [1994] (T371G PheCys). We are now investigating the 5′ flanking region. Only C129T had a frequency high enough to perform association (freq. of allele 1 = 0.84 freq. of allele 2 = 0.16) while the rest have a frequency of the minor allel

Mutational analysis of the 5-HT1B and 5-HT1E serotonin receptor genes in three datasets with schizophrenia.

We have investigated two serotonin receptor genes located in the 6q13-q26 area: the 5-ht1e and the 5-ht1b genes. Both receptors belong to the G-protein superfamily and contain the characteristic seven transmembrane regions, are localized in the brain, are intronless, and are negatively coupled to adenylyl cyclase. Both receptors have been studied by mutational analysis techniques by at least one other group [Shimron-Abarbanell et al., 1995; Nothen et al., 1994], in both cases association with schizophrenia was found negative. Therefore, we consider our mutational analysis work a "second pass." For the study of association, we have employed three clinical data sets (n = 180 families) that have supported the existence of a susceptibility gene for schizophrenia in 6q13-26 [Martinez et al., submitted]. We have found in a screening of 97 unrelated individuals (mostly Caucasians) the following new polymorphisms: 1) 5-ht1b. Silent DNA variations: C129T, C705T; missense DNA variations: C662A Thr-Asn, A1099G Ile-Val, G1120AGlu-Lys. We have also detected a variation previously reported by Nothen et al. [1994] (T371G PheCys). We are now investigating the 5′ flanking region. Only C129T had a frequency high enough to perform association (freq. of allele 1 = 0.84 freq. of allele 2 = 0.16) while the rest have a frequency of the minor allel

Genetic diversity of the human serotonin receptor 1B (HTR1B) gene

We systematically and comprehensively investigated polymorphisms of the HTR1B gene as well as their linkage disequilibrium and ancestral relationships. We have detected the following polymorphisms in our sample via denaturing gradient gel electrophoresis, database comparisons, and/or previously published assays: G-511T, T-261G, -182INS/DEL-181, A-161T, C129T, T371G, T655C, C705T, G861C, A1099G, G1120A, and A1180G. The results of the intermarker analyses showed strong linkage disequilibrium between the C129T and the G861C polymorphisms and revealed four common haplotypes: ancestral (via chimpanzee comparisons), 129T/861C, -161T, and -182DEL-181. The results of association tests with schizophrenia were negative, although A-161T had a nominal P = 0.04 via AS-PEX/sib_tdt. The expressed missense substitutions, Phe124Cys, Phe219Leu, Ile367Val, and Glu374Lys, could potentially affect ligand binding or interaction with G proteins and thus modify drug response in carriers of these variants. On average, the human cSNPs and differences among other primates clustered in the more thermodynamically unstable regions of the mRNA, which suggests that the evolutionary survival of nucleotide sequence variation may be influenced by the mRNA structure of this gene, (C) 2001 Academic Press