Gemin8 is a novel component of the survival motor neuron complex and functions in small nuclear ribonucleoprotein assembly.

The survival motor neuron (SMN) protein is the product of the spinal muscular atrophy disease gene. SMN and Gemin2\u20137 proteins form a large macromolecular complex that localizes in the cytoplasm as well as in the nucleoplasm and in nuclear Gems. The SMN complex interacts with several additional proteins and likely functions in multiple cellular pathways. In the cytoplasm, a subset of SMN complexes containing unrip and Sm proteins mediates the assembly of spliceosomal small nuclear ribonucleoproteins (snRNPs). Here, by mass spectrometry analysis of SMN complexes purified from HeLa cells, we identified a novel protein that is evolutionarily conserved in metazoans, and we named it Gemin8. Co-immunoprecipitation and immunolocalization experiments demonstrated that Gemin8 is associated with the SMN complex and is localized in the cytoplasm and in the nucleus, where it is highly concentrated in Gems. Gemin8 interacts directly with the Gemin6-Gemin7 heterodimer and, together with unrip, these proteins form a heteromeric subunit of the SMN complex. Gemin8 is also associated with Sm proteins, and Gemin8-containing SMN complexes are competent to carry out snRNP assembly. Importantly, RNA interference experiments indicate that Gemin8 knock-down impairs snRNP assembly, and Gemin8 expression is down-regulated in cells with low levels of SMN. These results demonstrate that Gemin8 is a novel integral component of the SMN complex and extend the repertoire of cellular proteins involved in the pathway of snRNP biogenesis

Os saberes docentes na formação inicial do professor de física: elaborando sentidos para o estágio supervisionado Teacher knowledge in initial teacher education: elaborating meanings for supervised teaching practice activities

Neste trabalho apresentamos os resultados de uma investigação a respeito da construção dos saberes docentes, durante a realização do estágio supervisionado da licenciatura de Física. Para o levantamento das informações desta pesquisa, foram entrevistados dois grupos de estagiários e analisados seus relatórios de regência. Durante as entrevistas, semiestruturadas, o estagiário era convidado a falar sobre a sua experiência com o estágio supervisionado. Buscamos perceber as representações que cada estagiário elaborou durante o estágio, em relação aos alunos, ao professor, à escola, aos outros estagiários de seu grupo e ao próprio estágio. Com base nessas representações, procuramos verificar quais saberes os estagiários conseguiram construir durante esse período e caracterizar a singularidade de sua ação docente.<br>In this work we present the results of research about the construction of the teacher´s knowledge, during the period of supervised teaching practice for students in a teacher education program in Physics. For the data collection, two groups of students had been interviewed; we also analyzed their reports of teaching practice. During the interviews, the students were invited to speak about their experiences on the supervised period of training. We were looking for the representations that each trainee elaborated during the period of training, related to the pupils, the teachers, the school and the other students of their groups. From these representations it was possible to verify the knowledge constructed by the trainees during the supervised teaching practice and to characterize the singularity of their practice teaching

The SMN interactome includes Myb-binding protein 1a

Understanding networks of interacting proteins is a major goal in cell biology. The survival of motor neurons protein (SMN) interacts, directly or indirectly, with a large number of other proteins and reduced levels of SMN cause the inherited disorder spinal muscular atrophy (SMA). Some SMN interactions are stable and stoichiometric, such as those with gemins, while others are expected to be transient and substoichiometric, such as the functional interaction of SMN with coilin in Cajal bodies. This study set out to determine whether novel components of the extensive SMN interactome can be identified by a proteomic approach. SMN complexes were immuno-precipitated from HeLa nuclear extracts, using anti-SMN monoclonal antibody attached to magnetic beads, digested with trypsin, separated by capillary-liquid chromatography and analyzed by MALDI TOF/TOF mass spectrometry. One-hundred and one proteins were detected with a p value of <0.05, SMN, gemins and U snRNPs being the dominant "hits". Sixty-nine of these were rejected after MALDI analysis of two control pull-downs using antibodies against unrelated nuclear proteins. The proteins found only in anti-SMN pulldowns were either known SMN partners, and/or contained dimethylated RG domains involved in direct interaction with the SMN tudor domain, or they were known binding partners of such direct SMN interactors. Myb-binding protein 1a, identified as a novel candidate, is a mainly nucleolar protein of unknown function but it partially colocalized with SMN in Cajal bodies in HeLa cell nucleoplasm and, like SMN, was reduced in cells from an SMA patient.Heidi R. Fuller, Nguyen Thi Man, Le Thanh Lam, Le Thiet Thanh, Rebecca A. Keough, Arndt Asperger, Thomas J. Gonda and Glenn E. Morri

Gemin3 Is an Essential Gene Required for Larval Motor Function and Pupation in Drosophila

The assembly of metazoan Sm-class small nuclear ribonucleoproteins (snRNPs) is an elaborate, step-wise process that takes place in multiple subcellular compartments. The initial steps, including formation of the core RNP, are mediated by the survival motor neuron (SMN) protein complex. Loss-of-function mutations in human SMN1 result in a neuromuscular disease called spinal muscular atrophy. The SMN complex is comprised of SMN and a number of tightly associated proteins, collectively called Gemins. In this report, we identify and characterize the fruitfly ortholog of the DEAD box protein, Gemin3. Drosophila Gemin3 (dGem3) colocalizes and interacts with dSMN in vitro and in vivo. RNA interference for dGem3 codepletes dSMN and inhibits efficient Sm core assembly in vitro. Transposon insertion mutations in Gemin3 are larval lethals and also codeplete dSMN. Transgenic overexpression of dGem3 rescues lethality, but overexpression of dSMN does not, indicating that loss of dSMN is not the primary cause of death. Gemin3 mutant larvae exhibit motor defects similar to previously characterized Smn alleles. Remarkably, appreciable numbers of Gemin3 mutants (along with one previously undescribed Smn allele) survive as larvae for several weeks without pupating. Our results demonstrate the conservation of Gemin3 protein function in metazoan snRNP assembly and reveal that loss of either Smn or Gemin3 can contribute to neuromuscular dysfunction