Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cotton (Gossypium hirsutum L.) fibers are single-celled trichomes that synchronously undergo a phase of rapid cell expansion, then a phase including secondary cell wall deposition, and finally maturation. To determine if there is coordinated regulation of gene expression during fiber expansion, we analyzed the expression of components involved in turgor regulation and a cytoskeletal protein by measuring levels of mRNA and protein accumulation and enzyme activity. Fragments of the genes for the plasma membrane proton-translocating ATPase, vacuole-ATPase, proton-translocating pyrophosphatase (PPase), phosphoenolpyruvate carboxylase, major intrinsic protein, and alpha-tubulin were amplified by polymerase chain reaction and used as probes in ribonuclease protection assays of RNA from a fiber developmental series, revealing two discrete patterns of mRNA accumulation. Transcripts of all but the PPase accumulated to highest levels during the period of peak expansion (+12-15 d postanthesis [dpa]), then declined with the onset of secondary cell wall synthesis. The PPase was constitutively expressed through fiber development. Activity of the two proton-translocating-ATPases peaked at +15 dpa, whereas PPase activity peaked at +20 dpa, suggesting that all are involved in the process of cell expansion but with varying roles. Patterns of protein accumulation and enzyme activity for some of the proteins examined suggest posttranslational regulation through fiber development.
 ...
PMID:Genes involved in osmoregulation during turgor-driven cell expansion of developing cotton fibers are differentially regulated. 953 73

In cultured rat hepatocytes, glucagon increased phosphoenolpyruvate carboxykinase mRNA transiently. Insulin, given at the maximal increase, enhanced the degradation by 3-fold. The levels of beta-actin mRNA and ribosomal RNA, which served as a control, remained unchanged. The transcriptional inhibitor, actinomycin D, or the serine/threonine phosphatase IIA inhibitor, okadaic acid, prevented the degradation of phosphoenolpyruvate carboxykinase mRNA. This indicated that the degradation of phosphoenolpyruvate carboxykinase mRNA requires the de novo synthesis of a bona fide destabilizing factor and/or active protein phosphatase. In vitro RNA degradation assays were developed in order to investigate whether insulin-treated cells contained enhanced ribonuclease activity. Fractionated cytosolic extracts were prepared by removing cell organelles by differential centrifugation and thereafter part of the cytosolic proteins by heat treatment. These extracts were incubated with exogenously added total RNA and the degradation of phosphoenolpyruvate carboxykinase mRNA, beta-actin mRNA and 28S ribosomal RNA was studied. In this assay, phosphoenolpyruvate carboxykinase mRNA and the otherwise stable beta-actin mRNA and ribosomal RNA were degraded 3-fold faster by extracts from insulin-treated, than from untreated, cells. The increase in RNase activity induced by insulin could be prevented by treatment of cultured rat hepatocytes with actinomycin D, indicating that ongoing gene transcription was required. The 'in vivo' specificity of the insulin effect on PCK mRNA degradation in cultured hepatocytes seemed to be lost in the in vitro assay in cytosolic extracts due to the disruption of the intracellular environment. Also in whole cell lysates, which were obtained by hypo-osmotic shock of the cells, and which contained the disrupted particulate and all soluble cellular components, PCK mRNA as well as beta-actin mRNA and ribosomal RNA, was degraded. The increase in ribonuclease activity due to insulin paralleled the insulin-induced acceleration of phosphoenolpyruvate carboxykinase mRNA degradation in cultured hepatocytes, which might indicate a functional correlation.
 ...
PMID:Parallel acceleration of phosphoenolpyruvate carboxykinase mRNA degradation and increase in ribonuclease activity induced by insulin in cultured rat hepatocytes. 970 51