Biomedical subjects

Luis M Salgado

Publications and source records attributed to Luis M Salgado.

6 recordsLinked to original sources

PubMed2006

Activities of the protein kinases STK, PI3K, MEK, and ERK are required for the development of the head organizer in Hydra magnipapillata.

The development of the hydra's head and its hypostome has been studied at the molecular level. Many genes have been cloned from hydra as potential candidates that control the development of its head. Much work was performed on the mechanisms controlling expression of these genes in the position-dependent manner. Moreover, there have been data to support the involvement of three main signaling pathways that involve PKC, SRC, and PI3K kinases in the regulation of the head formation and in the expression of several head-specific genes. In this report, we present data supporting the participation of these three signaling pathways on the development of the hypostome. We used grafting experiments and inhibitors of the specific kinases to show the participation of these enzymes in hypostome formation. From our results, we postulate that these signal transduction pathways regulate the very early stages of the head development, most likely at the point when the cells start to differentiate to form the head organizer.

Animals↗

PubMed2006

PI3K and ERK 1-2 regulate early stages during head regeneration in hydra.

Different signaling systems coordinate and regulate the development of a multicellular organism. In hydra, the canonical Wnt pathway and the signal transduction pathways mediated by PKC and Src regulate early stages of head formation. In this paper, we present evidence for the participation of a third pathway, the PI3K-PKB pathway, involved in this process. The data presented here are consistent with the participation of ERK 1-2 as a point of convergence for the transduction pathways mediated by PKC, Src and PI3K for the regulation of the regeneration of the head in hydra. The specific developmental point regulated by them appears to be the commitment of tissue at the apical end of the regenerate to form the head organizer.

Animals↗

PubMed2003

STK, the src homologue, is responsible for the initial commitment to develop head structures in Hydra.

STK, the Src tyrosine kinase homologous of the fresh water polyp hydra, is a key component of the signal transduction system for cell differentiation in this organism. Its activity is strongly increased 6 h after decapitation, and the inhibition of its activity with PP2/AG1879 prevents head development. We generated STK(-) polyps by using double-stranded RNA interference; STK activity of those polyps is blocked through time. STK RNAi silenced animals could not regenerate the head, but the foot, and could not reproduce asexually. The silencing of STK causes the development of ectopic heads in decapitated polyps in the first third of their body. Some head-specific genes, like Ks1, HyTcf, and Hybra1, seem to be regulated by the signaling pathway mediated by STK because their expression is modified in the STK(-) polyps. These findings support an important function for STK in the initial commitment of cells to develop head structures in hydra.

Animals↗

PubMed2003

Expression and characterization of the celcflB gene from Cellulomonas flavigena encoding an endo-beta-1,4-glucanase.

An endoglucanase gene called celcflB was isolated from a genomic library of C. flavigena. Its nucleotide sequence showed an ORF of 1725 bp with a GTG start codon. A promoter sequence was found inside the adjacent gene upstream from the start point of translation of celcflB gene. The gene celcflB was induced by sugarcane bagasse and repressed by glucose when C. flavigena was grown on these carbon sources, suggesting that celcflB gene is regulated at transcriptional level. The predicted amino acid sequence of the CelcflB protein presented a catalytic domain with a high homology to family 5 of glycosil hydrolases, and a cellulose binding domain identical to cellulose binding domains type II. The coding region of the celcflB gene was cloned into the expression vector pQE30 and the recombinant protein of 58 kDa presented endoglucanase activity towards carboxymethyl cellulose (CMC).

Carboxymethylcellulose Sodium↗

PubMed2003

High levels of palmitic acid lead to insulin resistance due to changes in the level of phosphorylation of the insulin receptor and insulin receptor substrate-1.

Insulin resistance is defined as the decrease in the glucose disposal in response to insulin by the target tissues. High concentrations of nonesterified fatty acids (NEFA) in plasma have been implicated with many insulin resistance states. We evaluated several aspects of the insulin resistance induced by palmitic acid in rats and found that after treatment with 0.09 g/kg of palmitic acid there is a delay in the curve of tolerance to glucose. We measured the changes in protein phosphorylation in samples from abdominus rectus muscle and there was a decrease of 64 and 75% in the levels of phosphorylation in tyrosine of the insulin receptor and insulin receptor substrate-1, respectively. This diminution in the tyrosine phosphorylation is consistent with a decrease in the main pathway known to be activated after insulin treatment, the mitogen activated protein kinases (MAPKs). If the animals were treated with inhibitors of PKC, like sphingosine, there was a prevention of the effect of palmitic acid determined at the level of tyrosine phosphorylation. According with this result, we found an increase in the phosphorylations in serine of the insulin receptor after the treatment with palmitate. These results suggest that PKC has a role as negative regulator (by phosphorylation in serine) of the insulin receptors activation in the insulin resistance induced by palmitic acid.

Animals↗

PubMed2002

Cellulomonas flavigena: characterization of an endo-1,4-xylanase tightly induced by sugarcane bagasse.

Xylanases, an important group of enzymes for biomass degradation in the industry, are commonly found forming complex multienzyme systems. As a preliminary step to the construction of efficient xylanase producers using genetic engineering, we have characterized a gene encoding an endo-beta-1,4 xylanase (xyncflA) from Cellulomonas flavigena. The xylanase activity and the xyncflA synthesis were higher when C. flavigena was grown on sugarcane bagasse. In this substrate, both activity and transcript increased with approximately the same rate during the culture period. When C. flavigena grew on glucose, low signal of mRNA was observed, suggesting that the xyncflA gene is regulated at the transcriptional level.

Cellulomonas↗