Project description:The glucose dual-affinity transport system (low- and high-affinity) is a conserved strategy exerted by microorganisms to cope with the naturally fluctuating availability of nutrients in the environment. The glucose sensing and uptaking process were believed to be tightly involved in cellulases expression regulation in cellulolytic fungi. However, both the identities and functions of the major molecular components of this evolutionarily conserved system in filamentous fungi remain elusive. Here, we conducted a systematic identification and characterization of the glucose dual-affinity transport system in the model fungus Neurospora crassa. Using RNA sequencing coupled with functional transport analyses, we were able to assign GLT-1 (Km = 18.42 ± 3.38 mM) and HGT-1/-2 (Km = 16.13 ± 0.95 µM and 98.97 ± 22.02 µM) to low- and high-affinity glucose transport systems, respectively. The high-affinity transporters hgt-1/-2 were able to complement a moderate growth defect under high glucose when glt-1 was deleted. Simultaneous deletion of hgt-1/-2 led to extensive derepression of genes for plant cell wall deconstruction on cellulose. This suppression by HGT-1/-2 was connected to both carbon catabolite repression (CCR) and the cyclic adenosine monophosphate-protein kinase A pathway. Alteration of a residue conserved across taxa for hexose-transporters was found to result in a loss of glucose-transporting function, whereas CCR signal transduction was retained, indicating a dual function for HGT-1/-2 as “transceptors”. In this study, GLT-1 and HGT-1/-2 are identified as the key components of the glucose dual-affinity transport system, which play diverse roles in glucose transport and carbon metabolism. Given their wide conservation across fungal species, the glucose dual-affinity transport components and their pleiotropic roles revealed in this study would shed extensive new light on the molecular basis of nutrient transport, signaling, and plant cell wall degradation in fungi.
Project description:Influenza virus neuraminidase (NA), a type II transmembrane glycoprotein, is transported to the virus assembly site at the plasma membrane and is a major viral envelope component that plays a critical role in the release of progeny virions and in determination of host range restriction. Although signals/sequences in NA for translocation, sorting and raft association have been identified, little is known about the host factors that are involved in regulating the intracellular and cell surface transport of NA. In this report, we have investigated the involvement of Rho family GTPases in NA transport to the cell surface. We found that expression of constitutively active or inactive mutants of RhoA or Rac1 did not significantly affect the amount of NA that reached the cell surface. Interestingly, expression of constitutively active Cdc42 or depletion of the Cdc42-specific GAP, ARHGAP21, promoted the transport of NA to the plasma membranes. By contrast, cells expressing shRNA targrting Cdc42 or overexpressing ARHGAP21 exhibited a significant decrease in the amount of cell surface-localized NA. Furthermore, silencing of Cdc42 or ARHGAP21 had significant effects on influenza A virus replication. Together, our results reveal that ARHGAP21 and Cdc42-based signaling regulates the NA transport and thereby impacts virus replication. This microarray experiment was carried out to find out whether Cdc42 and ARHGAP21 expression levels in A549 cell were changed after WSN infection.
Project description:Influenza virus neuraminidase (NA), a type II transmembrane glycoprotein, is transported to the virus assembly site at the plasma membrane and is a major viral envelope component that plays a critical role in the release of progeny virions and in determination of host range restriction. Although signals/sequences in NA for translocation, sorting and raft association have been identified, little is known about the host factors that are involved in regulating the intracellular and cell surface transport of NA. In this report, we have investigated the involvement of Rho family GTPases in NA transport to the cell surface. We found that expression of constitutively active or inactive mutants of RhoA or Rac1 did not significantly affect the amount of NA that reached the cell surface. Interestingly, expression of constitutively active Cdc42 or depletion of the Cdc42-specific GAP, ARHGAP21, promoted the transport of NA to the plasma membranes. By contrast, cells expressing shRNA targrting Cdc42 or overexpressing ARHGAP21 exhibited a significant decrease in the amount of cell surface-localized NA. Furthermore, silencing of Cdc42 or ARHGAP21 had significant effects on influenza A virus replication. Together, our results reveal that ARHGAP21 and Cdc42-based signaling regulates the NA transport and thereby impacts virus replication. This microarray experiment was carried out to find out whether Cdc42 and ARHGAP21 expression levels in A549 cell were changed after WSN infection. Total RNAs were extracted from three different groups of A549 cells that had been infected with or without WSN for 10 h, using TRIzol reagent (Invitrogen, Carlsbad, CA). Samples were amplified and labeled using a NimbleGen One-Color DNA Labeling Kit.
Project description:Staphylococcus xylosus is used as starter culture for sausage fermentation for a long time but the molecular mechanisms for its adaptation in meat remained unknown. A global transcriptomic approach was carried out to determine these molecular mechanisms. S. xylosus modulated the expression of about 30% of the total genes during its growth and survival in the meat model. The expression of many genes encoding enzymes involved in glucose and lactate catabolism was up regulated. In parallel, genes encoding transport of peptides and peptidases that could furnish amino acids were up expressed and thus concomitantly a lot of genes involved in amino acids synthesis were down regulated. Finally S. xylosus responded to salt added in the meat model by over expressing genes involved in transport and synthesis of osmoprotectants, Na+ and H+ extrusion and in production of energy through the F0F1-ATPase.
Project description:Staphylococcus xylosus is used as starter culture for sausage fermentation for a long time but the molecular mechanisms for its adaptation in meat remained unknown. A global transcriptomic approach was carried out to determine these molecular mechanisms. S. xylosus modulated the expression of about 30% of the total genes during its growth and survival in the meat model. The expression of many genes encoding enzymes involved in glucose and lactate catabolism was up regulated. In parallel, genes encoding transport of peptides and peptidases that could furnish amino acids were up expressed and thus concomitantly a lot of genes involved in amino acids synthesis were down regulated. Finally S. xylosus responded to salt added in the meat model by over expressing genes involved in transport and synthesis of osmoprotectants, Na+ and H+ extrusion and in production of energy through the F0F1-ATPase. Microarray was used to evaluate modification in the transcriptome of S. xylosus C2a strain in the inoculum (Mx) or in meat (V). Three biological replicates were collected on separate days for samples and labelled following a dye-switch design; for each condition one labeling in Cy3 and one in Cy5.
Project description:Insulin action in adipocytes affects whole-body insulin sensitivity. Studies of adipose-specific Glut4 knockout mice have established that adipose Glut4 contributes to the control of systemic glucose homeostasis. Presumably, this reflects a role for Glut4-mediated glucose transport in the regulation of secreted adipokines. In cultured 3T3-L1 adipocytes, Rab10 GTPase is required for insulin-stimulated translocation of Glut4 (Sano et al., 2007). The physiological importance of adipose Rab10 and the significance of its role in the control of Glut4 vesicle trafficking in vivo are unknown. Here we report that adipocytes from adipose-specific Rab10 knockout mice have a ~50% reduction in glucose uptake and Glut4 translocation to the cell surface in response to insulin, demonstrating a role for Rab10 in Glut4 trafficking. Moreover, hyperinsulinemic-euglycemic clamp shows decreased whole-body glucose uptake as well as impaired suppression of hepatic glucose production in adipose Rab10 knockout mice. Thus, fully functional Glut4 vesicle trafficking in adipocytes is critical for maintaining insulin sensitivity. Comparative transcriptome analysis of perigonadal adipose tissue demonstrates significant transcriptional similarities between adipose Rab10 knockout mice and adipose Glut4 knockout mice, consistent with the notion that the phenotypic similarities between the two models are mediated by reduced insulin-stimulated glucose transport into adipocytes. Transcriptome sequencing of perigonadal white adipose tissue
Project description:Responses of Escherichia coli as they recover from one stationary phase in 10 mM Na-P + 0.2 % glucose at OD 0.4 Keywords: time course
Project description:Hyperglycemia-induced damage to bone formations and function has been recognized.However, as the largest connective tissue organ, whether bone and osteocytes in turn regulate blood sugar and insulin sensitivity has not been addressed. Here we identified a novel protein termed intraflagellar transport 140 with functional importance in regulating osteogenesis, which is also related to the osteoblastic insulin sensitivity. We established Ift140 osteoblastic conditional knockout mice model, and found that blood glucose metabolism could be regulated through osteoblastic IFT140 interacting with O-GlcNAc transferase to regulate insulin signaling. The discovery provides new insight for two-way regulation between bone and glucose metabolism, and also exploring potential new target for blood glucose interventions.