Non-Muscle Myosin IIA (Myh9) is in the Nucleus of S-Phase Entering NT2-D1 Cells

Non-muscle myosin IIA is a cytoplasmic protein that works in concert with F-actin to produce cell movement. The heavy chain of this protein is codified by the MYH9 gene. The presence of motor proteins as myosin or mono and F-actin and their role in transcription has recently been observed. Prep1–the transcription factor of HOXB genes– constitutes a dimer with Pbx1, which induces HOXB gene expression. Prep1 has been found purifying with ?-actin and Myh9. HOXB transcription initiates when cells enter in S-phase, during which DNA duplication and transcription occur at the same time. Here, we have shown that Myh9 co-localizes with Prep1 in the nucleus and in the periphery of the nucleolus in S-phase NT2-D1 cells. Furthermore, we have shown that Myh9 purifies with Pbx1 from nuclear extracts of S-phase entering NT2-D1 cells –and not from cytoplasmic extracts. Taking into account these results, we conclude that Myh9 is in the nucleus of the S-phase entering NT2-D1 cells and might have a role in HOXB transcription

Non-Muscle Myosin IIA (Myh9) is in the Nucleus of S-Phase Entering NT2-D1 Cells

Non-muscle myosin IIA is a cytoplasmic protein that works in concert with F-actin to produce cell movement. The heavy chain of this protein is codified by the MYH9 gene. The presence of motor proteins as myosin or mono and F-actin and their role in transcription has recently been observed. Prep1–the transcription factor of HOXB genes– constitutes a dimer with Pbx1, which induces HOXB gene expression. Prep1 has been found purifying with β-actin and Myh9. HOXB transcription initiates when cells enter in S-phase, during which DNA duplication and transcription occur at the same time. Here, we have shown that Myh9 co-localizes with Prep1 in the nucleus and in the periphery of the nucleolus in S-phase NT2-D1 cells. Furthermore, we have shown that Myh9 purifies with Pbx1 from nuclear extracts of S-phase entering NT2-D1 cells –and not from cytoplasmic extracts. Taking into account these results, we conclude that Myh9 is in the nucleus of the S-phase entering NT2-D1 cells and might have a role in HOXB transcription.Centro Regional de Estudios Genómico

Nuclear actin polymerization from faster growing ends in the initial activation of hox gene transcription : Are nuclear speckles involved?

The HoxB cluster expression is activated by retinoic acid and transcribed in a collinear manner. The DNA-binding Pknox1-Pbx1 complex modulates Hox protein activity. Here, NT2-D1 teratocarcinoma cells -a model of Hox gene expression- were used to show that upon retinoic acid induction, Pknox1 co-localizes with polymeric nuclear actin. We have found that globular actin aggregates, polymeric actin, the elongating RNA polymerase II and THOC match euchromatic regions corresponding to nuclear speckles. Moreover, RNA polymerase II, N-WAS P, and transcription/splicing factors p54nrb and PSF were validated as Pknox1 interactors by tandem affinity purification. PSF pulled down with THOC and nuclear actin, both of which co-localize in nuclear speckles. Although latrunculin A slightly decreases the general level of HoxB gene expression, inhibition of nuclear actin polymerization by cytochalasin D blocks the expression of HoxB transcripts in a collinear manner. Thus, our results support the hypothesis that nuclear actin polymerization is involved in the activation of HoxB gene expression by means of nuclear speckles.Centro Regional de Estudios Genómico

The complete nucleotide sequence of a Spanish isolate of <i>Citrus psorosis</i> virus: comparative analysis with other ophioviruses

The complete genomic sequence (11278 nt) of Citrus psorosis virus (CPsV), isolate P-121 from Spain, was determined and compared with those from isolate CPV-4 and from other ophioviruses. The three RNAs of P-121 had similar size and identical organization as those of CPV-4. The 24K and the RdRp proteins were potentially encoded in the viral complementary (vc) strand of RNA 1, the 54K protein potentially encoded in vcRNA 2 and the coat protein encoded in vcRNA 3. These four proteins from P-121 and CPV-4 had 87, 92, 93 and 94% amino acid identity, respectively, but only 22, 38, 25 and 33% identity with their homologous proteins from Mirafiori lettuce big vein virus (MLBVV), the only other ophiovirus completely sequenced. Biological and genetic differences between CPsV and MLBVV (and the other ophioviruses), would support their future allocation in different genera within a tentative family Ophioviridae.Instituto de Biotecnología y Biología Molecula

Regulación GABAérgica de los ritmos biológicos

Muchos procesos bioquímicos, fisiológicos y comportamentales fluctúan rítmicamente con una periodicidad diurna o anual en condiciones naturales. En los mamíferos, el reloj circadiano involucrado en la generación de muchos ritmos diarios está constituido por los núcleos supraquiasmáticos (NSQ) del hipotálamo. Para numerosas especies, el ciclo de luz-oscuridad es la señal primaria ambiental que sincroniza y reajusta el reloj circadiano a un período de exactamente 24 hs. La función predictiva del sistema circadiano es preponderante: ella confiere una ventaja adaptativa al organismo pues activa respuestas efectoras con la antelación suficiente como para que sean adaptativamente adecuadas. La diferenciación de las especies vivientes en nocturnas, diurnas o crepusculares, de acuerdo al momento en que muestran su actividad, indica la poderosa fuerza modeladora que la noche y el día han tenido en el proceso de la evolución. Así, el desarrollo de conductas estacionales como la hibernación o la actividad reproductora subraya la importancia de los ritmos anuales en la función biológica. En cuanto a los neurotransmisores presentes en los NSQ, debe mencionarse que el GABA es el principal, ya que se encuentra en todas las neuronas de los mismos. El papel que desempeñan las neuronas GABAérgicas en el procesamiento de la información neural es relevante, dado que constituye el neurotransmisor inhibitorio más abundante en el sistema nervioso central de los mamíferos. El GABA está presente en interneuronas de tipo Golgi II, que median la integración y el procesamiento de la información en las distintas estructuras corticales y subcorticales. Las sinapsis GABAérgicas constituyen las más importantes en el control “fino” del comportamiento de los mamíferos, las cuales permitirían la variabilidad de las conductas de este grupo, indispensables para su adaptación al medio.Facultad de Ciencias Naturales y Muse

The complete nucleotide sequence of a Spanish isolate of <i>Citrus psorosis</i> virus: comparative analysis with other ophioviruses

The complete genomic sequence (11278 nt) of Citrus psorosis virus (CPsV), isolate P-121 from Spain, was determined and compared with those from isolate CPV-4 and from other ophioviruses. The three RNAs of P-121 had similar size and identical organization as those of CPV-4. The 24K and the RdRp proteins were potentially encoded in the viral complementary (vc) strand of RNA 1, the 54K protein potentially encoded in vcRNA 2 and the coat protein encoded in vcRNA 3. These four proteins from P-121 and CPV-4 had 87, 92, 93 and 94% amino acid identity, respectively, but only 22, 38, 25 and 33% identity with their homologous proteins from Mirafiori lettuce big vein virus (MLBVV), the only other ophiovirus completely sequenced. Biological and genetic differences between CPsV and MLBVV (and the other ophioviruses), would support their future allocation in different genera within a tentative family Ophioviridae.Instituto de Biotecnología y Biología Molecula

Induction of HoxB Transcription by Retinoic Acid Requires Actin Polymerization

We have analyzed the role of actin polymerization in retinoic acid (RA)-induced HoxB transcription, which is mediated by the HoxB regulator Prep1. RA induction of the HoxB genes can be prevented by the inhibition of actin polymerization. Importantly, inhibition of actin polymerization specifically affects the transcription of inducible Hox genes, but not that of their transcriptional regulators, the RARs, nor of constitutively expressed, nor of actively transcribed Hox genes. RA treatment induces the recruitment to the HoxB2 gene enhancer of a complex composed of “elongating” RNAPII, Prep1, β-actin, and N-WASP as well as the accessory splicing components p54Nrb and PSF. We show that inhibition of actin polymerization prevents such recruitment. We conclude that inducible Hox genes are selectively sensitive to the inhibition of actin polymerization and that actin polymerization is required for the assembly of a transcription complex on the regulatory region of the Hox genes