RESUMEN
Astragalus membranaceus var. mongholicus (AMM), a member of the Leguminosae, is one of the most important medicinal plants worldwide. The dried roots of AMM have a wide range of pharmacological effects and are a traditional Chinese medicine. Here, we report the first chromosome-level reference genome of AMM, comprising nine pseudochromosomes with a total size of 1.47 Gb and 27 868 protein-encoding genes. Comparative genomic analysis reveals that AMM has not experienced an independent whole-genome duplication (WGD) event after the WGD event shared by the Papilionoideae species. Analysis of long terminal repeat retrotransposons suggests a recent burst of these elements at approximately 0.13 million years ago, which may explain the large size of the AMM genome. Multiple gene families involved in the biosynthesis of triterpenoids and flavonoids were expanded, and our data indicate that tandem duplication has been the main driver for expansion of these families. Among the expanded families, the phenylalanine ammonia-lyase gene family was primarily expressed in the roots of AMM, suggesting their roles in the biosynthesis of phenylpropanoid compounds. The functional versatility of 2,3-oxidosqualene cyclase genes in cluster III may play a critical role in the diversification of triterpenoids in AMM. Our findings provide novel insights into triterpenoid and flavonoid biosynthesis and can facilitate future research on the genetics and medical applications of AMM.
Asunto(s)
Plantas Medicinales , Triterpenos , Astragalus propinquus/genética , Flavonoides/análisis , Raíces de Plantas/genéticaRESUMEN
Signalling through the IGF1R [type 1 IGF (insulin-like growth factor) receptor] and canonical Wnt signalling are two signalling pathways that play critical roles in regulating neural cell generation and growth. To determine whether the signalling through the IGF1R can interact with the canonical Wnt signalling pathway in neural cells in vivo, we studied mutant mice with altered IGF signalling. We found that in mice with blunted IGF1R expression specifically in nestin-expressing neural cells (IGF1RNestin-KO mice) the abundance of neural ß-catenin was significantly reduced. Blunting IGF1R expression also markedly decreased: (i) the activity of a LacZ (ß-galactosidase) reporter transgene that responds to Wnt nuclear signalling (LacZTCF reporter transgene) and (ii) the number of proliferating neural precursors. In contrast, overexpressing IGF-I (insulin-like growth factor I) in brain markedly increased the activity of the LacZTCF reporter transgene. Consistently, IGF-I treatment also markedly increased the activity of the LacZTCF reporter transgene in embryonic neuron cultures that are derived from LacZTCF Tg (transgenic) mice. Importantly, increasing the abundance of ß-catenin in IGF1RNestin-KO embryonic brains by suppressing the activity of GSK3ß (glycogen synthase kinase-3ß) significantly alleviated the phenotypic changes induced by IGF1R deficiency. These phenotypic changes includes: (i) retarded brain growth, (ii) reduced precursor proliferation and (iii) decreased neuronal number. Our current data, consistent with our previous study of cultured oligodendrocytes, strongly support the concept that IGF signalling interacts with canonical Wnt signalling in the developing brain to promote neural proliferation. The interaction of IGF and canonical Wnt signalling plays an important role in normal brain development by promoting neural precursor proliferation.
Asunto(s)
Regulación del Desarrollo de la Expresión Génica/genética , Neuronas/fisiología , Receptor IGF Tipo 1/fisiología , Transducción de Señal/fisiología , Proteínas Wnt/metabolismo , Adyuvantes Inmunológicos/farmacología , Animales , Encéfalo/anomalías , Encéfalo/efectos de los fármacos , Encéfalo/embriología , Proliferación Celular/efectos de los fármacos , Células Cultivadas , Embrión de Mamíferos , Inhibidores Enzimáticos/farmacología , Lóbulo Frontal/citología , Regulación del Desarrollo de la Expresión Génica/efectos de los fármacos , Cloruro de Litio/farmacología , Ratones , Ratones Transgénicos , Neuronas/efectos de los fármacos , ARN Mensajero/metabolismo , Receptor IGF Tipo 1/genética , Transducción de Señal/efectos de los fármacos , Tiazoles/farmacología , Urea/análogos & derivados , Urea/farmacología , Proteínas Wnt/genética , beta Catenina/genética , beta Catenina/metabolismo , beta-Galactosidasa/genética , beta-Galactosidasa/metabolismoRESUMEN
By promoting cell proliferation, survival and maturation insulin-like growth factor (IGF)-I is essential to the normal growth and development of the central nervous system. It is clear that IGF-I actions are primarily mediated by the type I IGF receptor (IGF1R), and that phosphoinositide 3 (PI3)-Akt kinases and MAP kinases signal many of IGF-I-IGF1R actions in neural cells, including oligodendrocyte lineage cells. The precise downstream targets of these signaling pathways, however, remain to be defined. We studied oligodendroglial cells to determine whether beta-catenin, a molecule that is a downstream target of glycogen synthase kinase-3beta (GSK3beta) and plays a key role in the Wnt canonical signaling pathway, mediates IGF-I actions. We found that IGF-I increases beta-catenin protein abundance within an hour after IGF-I-induced phosphorylation of Akt and GSK3beta. Inhibiting the PI3-Akt pathway suppressed IGF-I-induced increases in beta-catenin and cyclin D1 mRNA, while suppression of GSK3beta activity simulated IGF-I actions. Knocking-down beta-catenin mRNA by RNA interference suppressed IGF-I-stimulated increases in the abundance of cyclin D1 mRNA, cell proliferation, and cell survival. Our data suggest that beta-catenin is an important downstream molecule in the PI3-Akt-GSK3beta pathway, and as such it mediates IGF-I upregulation of cyclin D1 mRNA and promotion of cell proliferation and survival in oligodendroglial cells.
Asunto(s)
Proliferación Celular , Ciclina D/metabolismo , Factor I del Crecimiento Similar a la Insulina/metabolismo , Oligodendroglía/fisiología , beta Catenina/metabolismo , Animales , Línea Celular , Supervivencia Celular/fisiología , Células Cultivadas , Glucógeno Sintasa Quinasa 3/metabolismo , Glucógeno Sintasa Quinasa 3 beta , Fosforilación , Proteínas Proto-Oncogénicas c-akt/metabolismo , ARN Mensajero/metabolismo , Ratas , Ratas Wistar , Transducción de Señal , Células Madre/fisiología , Factores de TiempoRESUMEN
Both in vivo and in vitro studies indicate a correlation between reduced acetylation of histone core proteins and oligodendrocyte development. The nature of these histone modifications and the mechanisms mediating them remain undefined. To address these issues, we utilized OL-1 cells, a rat nontransformed oligodendrocyte cell line, and primary oligodendrocyte cultures. We found that the acetylated histone H3 at lysine 9 and lysine 14 (H3K9/K14ac) is reduced in both the myelin basic protein (MBP) and proteolipid protein (PLP) genes of maturing oligodendroglial OL-1 cells, and furthermore, this temporally correlates with increases in MBP, PLP, and histone deacetylase (HDAC) 11 expression. Disruption of developmentally-regulated histone H3 deacetylation within the MBP and PLP genes by the HDAC inhibitor trichostatin A blunts MBP and PLP expression. With its increased expression, interaction of HDAC 11 with acetylated histone H3 and recruitment of HDAC 11 to the MBP and PLP genes markedly increases in maturing OL-1 cells. Moreover, suppressing HDAC 11 expression with small interfering RNA significantly (1) increases H3K9/K14ac globally and within the MBP and PLP genes, (2) decreases MBP and PLP mRNA expression, and (3) blunts the morphological changes associated with oligodendrocyte development. Our data strongly support a specific role for HDAC 11 in histone deacetylation and in turn the regulation of oligodendrocyte-specific protein gene expression and oligodendrocyte development.
Asunto(s)
Diferenciación Celular/genética , Regulación del Desarrollo de la Expresión Génica/fisiología , Histona Desacetilasas/fisiología , Oligodendroglía/citología , Oligodendroglía/enzimología , Animales , Animales Recién Nacidos , Línea Celular , Línea Celular Tumoral , Células Cultivadas , Humanos , Ratas , Células Madre/citología , Células Madre/enzimologíaRESUMEN
Recent studies indicate that neural cell development in the central nervous system (CNS) correlates with a reduction in acetylation of histone core proteins. Moreover, histone hypoacetylation is thought to be important to oligodendrocyte lineage development. The mechanisms mediating the reduction in acetylation during postnatal neural development remain to be defined. To begin to understand these mechanisms, we investigated the expression of histone deacetylase 11 (HDAC11), a newly identified HDAC, in mouse brain during postnatal development. We show that HDAC11 was widely expressed in the brain and that this expression gradually increased in a region-specific pattern between birth and 4 weeks of age. At the cellular level HDAC11 protein was predominately localized in the nuclei of mature oligodendrocytes but only minimally in astrocytes. Although dentate gyrus granule neurons abundantly expressed HDAC11, granule neuron precursors in the subgranule layer exhibited little HDAC11 immunoreactivity. Double-immunostaining of the corpus callosum and dentate gyrus demonstrated that HDAC11 and Ki67, a cell-proliferating marker, are rarely colocalized in same cells. Our data show that HDAC11 was expressed in the developing brain in a temporal and spatial pattern that correlates with the maturation of neural cells, including cells of the oligodendrocyte lineage. These findings support a role for HDAC11 in CNS histone deacetylation and the development of oligodendrocytes and neurons during postnatal development.
Asunto(s)
Envejecimiento/metabolismo , Encéfalo/enzimología , Encéfalo/crecimiento & desarrollo , Histona Desacetilasas/metabolismo , Animales , Astrocitos/enzimología , Encéfalo/citología , Linaje de la Célula , Núcleo Celular/enzimología , Senescencia Celular , Cuerpo Calloso/citología , Cuerpo Calloso/enzimología , Cuerpo Calloso/metabolismo , Giro Dentado/citología , Giro Dentado/enzimología , Giro Dentado/metabolismo , Técnicas Inmunológicas , Antígeno Ki-67/metabolismo , Ratones , Ratones Endogámicos C57BL , Neuronas/citología , Neuronas/fisiología , Oligodendroglía/citología , Oligodendroglía/enzimología , Oligodendroglía/fisiología , Coloración y Etiquetado , Células Madre/citología , Células Madre/enzimología , Distribución TisularRESUMEN
Several studies have shown that the angiotensin-converting enzyme (ACE) I allele is associated with enhanced physical performance. We investigated whether this phenomenon is observed in a cohort of 67 Chinese men in Singapore. Angiotensin-converting enzyme ID polymorphism was typed with PCR method and maximal oxygen uptake (VO(2max)) of the DD, ID, and II genotypes was compared. Analysis of covariance revealed that VO(2max) was significantly higher (p<0.05) for the DD genotype (57.86 +/- 3.5 ml.kg.(-1)min(-1)) versus the ID (50.58 +/- 1.80 ml.kg.(-1)min(-1)) or II (50.48 +/- 1.58 ml.kg.(-1) min(-1)) genotype. Our findings suggest that the ACE DD genotype in young adult Chinese males is associated with higher levels of VO(2max).