RESUMEN
Cilia play a key role in the regulation of signaling pathways required for embryonic development, including the proper formation of the neural tube, the precursor to the brain and spinal cord. Forward genetic screens were used to generate mouse lines that display neural tube defects (NTD) and secondary phenotypes useful in interrogating function. We describe here the L3P mutant line that displays phenotypes of disrupted Sonic hedgehog signaling and affects the initiation of cilia formation. A point mutation was mapped in the L3P line to the gene Rsg1, which encodes a GTPase-like protein. The mutation lies within the GTP-binding pocket and disrupts the highly conserved G1 domain. The mutant protein and other centrosomal and IFT proteins still localize appropriately to the basal body of cilia, suggesting that RSG1 GTPase activity is not required for basal body maturation but is needed for a downstream step in axonemal elongation.
Asunto(s)
Cilios , Tubo Neural , Animales , Ratones , Cilios/metabolismo , Cilios/genética , Proteínas Hedgehog/metabolismo , Proteínas Hedgehog/genética , Tubo Neural/embriología , Tubo Neural/metabolismo , Defectos del Tubo Neural/genética , Defectos del Tubo Neural/metabolismo , Mutación Puntual , Transducción de SeñalRESUMEN
BACKGROUND: Cilia are important for Hedgehog signaling in vertebrates and many genes that encode proteins involved in ciliogenesis have been studied for their roles in embryonic development. Null mutations in many of these genes cause early embryonic lethality, hence an understanding of their roles in postnatal development is limited. RESULTS: The Inturned (Intu) gene is required for ciliogenesis and here we report a recessive hypomorphic mutation, resulting in substitution of a conserved hydrophobic residue (I813N) near the C-terminus, that sheds light on later functions of Intu. Mice homozygous for this Double-thumb (Intu(Dtm)) allele exhibit polydactyly, retarded growth, and reduced survival. There is a moderate loss of cilia in Intu(Dtm/Dtm) mutants, and Intu(I813N) exhibits compromised ability to increase ciliogenesis in cultured Intu null mutant cells. Intu(Dtm) mutants show rib defects and delay of endochondral ossification in long bones, digits, vertebrae, and the sternum. These skeletal defects correlate with a decrease in Hh signaling. However, patterning of the neural tube and planar cell polarity appear to be normal. CONCLUSIONS: This hypomorphic Intu allele highlights an important role of Intu in mouse skeletal development.
Asunto(s)
Anomalías Múltiples/genética , Proteínas de la Membrana/fisiología , Mutación Missense , Osteogénesis/genética , Mutación Puntual , Anomalías Múltiples/embriología , Alelos , Secuencia de Aminoácidos , Sustitución de Aminoácidos , Animales , Huesos/anomalías , Huesos/embriología , Polaridad Celular , Células Cultivadas , Cilios/ultraestructura , Trastornos del Crecimiento/genética , Proteínas Hedgehog/fisiología , Proteínas de la Membrana/genética , Ratones , Datos de Secuencia Molecular , Defectos del Tubo Neural/genética , Receptores Patched , Polidactilia/embriología , Polidactilia/genética , Estructura Terciaria de Proteína , Receptores de Superficie Celular/biosíntesis , Receptores de Superficie Celular/genética , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Transducción de Señal/genéticaRESUMEN
The formation of the embryonic brain and spinal cord begins as the neural plate bends to form the neural folds, which meet and adhere to close the neural tube. The neural ectoderm and surrounding tissues also coordinate proliferation, differentiation, and patterning. This highly orchestrated process is susceptible to disruption, leading to neural tube defects (NTDs), a common birth defect. Here, we highlight genetic and epigenetic contributions to neural tube closure. We describe an online database we created as a resource for researchers, geneticists, and clinicians. Neural tube closure is sensitive to environmental influences, and we discuss disruptive causes, preventative measures, and possible mechanisms. New technologies will move beyond candidate genes in small cohort studies toward unbiased discoveries in sporadic NTD cases. This will uncover the genetic complexity of NTDs and critical gene-gene interactions. Animal models can reveal the causative nature of genetic variants, the genetic interrelationships, and the mechanisms underlying environmental influences.
Asunto(s)
Encéfalo/crecimiento & desarrollo , Epigénesis Genética , Tubo Neural/crecimiento & desarrollo , Médula Espinal/crecimiento & desarrollo , Animales , Encéfalo/embriología , Femenino , Cresta Neural/embriología , Cresta Neural/crecimiento & desarrollo , Placa Neural/embriología , Placa Neural/crecimiento & desarrollo , Tubo Neural/embriología , Médula Espinal/embriologíaAsunto(s)
Atención a la Salud/tendencias , Manejo de la Enfermedad , Disrafia Espinal/terapia , Niño , HumanosRESUMEN
Experiments were carried out to examine the effects of nitrogen source on nitrogen incorporation into cyanophycin during nitrogen limitation and repletion, both with or without inhibition of protein synthesis, in cyanobacteria grown on either nitrate or ammonium. The use of nitrate and ammonium, 14N labeled in the growth medium and 15N labeled in the repletion medium, allows the determination of the source of nitrogen in cyanophycin using proton nuclear magnetic resonance spectroscopy. The data suggest that nitrogen from both the breakdown of cellular protein (14N) and directly from the medium (15N) is incorporated into cyanophycin. Nitrogen is incorporated into cyanophycin at different rates and to different extents, depending on the source of nitrogen (ammonium or nitrate) and whether the cells are first starved for nitrogen. These differences appear to be related to the activity of nitrate reductase in cells and to the possible expression of cyanophycin synthetase during nitrogen starvation.
Asunto(s)
Nitrógeno/metabolismo , Proteínas de Plantas/biosíntesis , Synechocystis/metabolismo , Proteínas Bacterianas , Estrés Oxidativo , Proteínas de Plantas/metabolismoRESUMEN
Human prostatic acid phosphatase (PAcP) was used as a valuable surrogate marker for monitoring prostate cancer prior to the availability of prostate-specific antigen (PSA). Even though the level of PAcP is increased in the circulation of prostate cancer patients, its intracellular level and activity are greatly diminished in prostate cancer cells. Recent advances in understanding the function of the cellular form of PAcP (cPAcP) have shed some light on its role in prostate carcinogenesis, which may have potential applications for prostate cancer therapy. It is now evident that cPAcP functions as a neutral protein tyrosine phosphatase (PTP) in prostate cancer cells and dephosphorylates HER-2/ErbB-2/Neu (HER-2: human epidermal growth factor receptor-2) at the phosphotyrosine (p-Tyr) residues. Dephosphorylation of HER-2 at its p-Tyr residues results in the down-regulation of its specific activity, which leads to decreases in growth and tumorigenicity of those cancer cells. Conversely, decreased cPAcP expression correlates with hyperphosphorylation of HER-2 at tyrosine residues and activation of downstream extracellular signal-regulated kinase (ERK)/mitogen activated protein kinase (MAPK) signaling, which results in prostate cancer progression as well as androgen-independent growth of prostate cancer cells. These in vitro results on the effect of cPAcP on androgen-independent growth of prostate cancer cells corroborate the clinical findings that cPAcP level is greatly decreased in advanced prostate cancer and provide insights into one of the molecular mechanisms involved in prostate cancer progression. Results from experiments using xenograft animal models further indicate a novel role of cPAcP as a tumor suppressor. Future studies are warranted to clarify the use of cPAcP as a therapeutic agent in human prostate cancer patients.