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Biomedical subjects

L D Garren

Publications and source records attributed to L D Garren.

At least 19 recordsLinked to original sources
PubMed1972

Control of transcription of RNA rich in polyadenylic acid in human lymphocytes.

Rapidly labeled polyribosomal RNA rich in poly(A) has been isolated from cultures of highly purified human peripheral blood lymphocytes. Messenger RNA function for this RNA is suggested by its ability to direct [3H]Met-tRNA binding to ribosomes and incorporation of amino acids into protein in a cell-free preparation. Phytohemagglutinin and low concentrations of dibutyryl cAMP (40 nM) increase poly(A)-rich RNA synthesis 40% within 2 hr, and 100-300% by 12 hr; the percent poly(A) content and the size of the poly(A)-rich portion remain constant. Higher concentrations of dibutyryl cAMP (1 nM), which prevent morphological transformation of lymphocytes by phytohemagglutinin, inhibit synthesis of poly(A)-rich RNA in phytohemagglutinin-treated lymphocytes without damaging cells. Cortisol (0.1 mM), which also prevents lymphocyte transformation, inhibits poly(A)-rich RNA synthesis by 80%. Cycloheximide (5 micro/ml), which decreases protein synthesis by 90%, decreases poly(A)-rich RNA synthesis 80% in cells stimulated by phytohemagglutinin. These studies demonstrate that, as part of the early molecular events of their action, phytohemagglutinin and cortisol regulate transcription of adenylate-rich RNA in human lymphocytes, and that similar transcriptional effects can be produced by dibutyryl cAMP.

Adenine Nucleotides↗
PubMed1971

Inhibition of replication in functional mouse adrenal tumor cells by adrenocorticotropic hormone mediated by adenosine 3':5'-cyclic monophosphate.

Adrenocorticotropic hormone (ACTH) inhibited replication in functional adrenal tumor cells with a concomitant stimulation of steroidogenesis and a characteristic change of morphology from a flattened to a spherical type. [(3)H]Thymidine incorporation into DNA was inhibited by about 50% 6 hours after ACTH treatment. Both cyclic AMP and dibutyryl cyclic AMP inhibited [(3)H]thymidine incorporation and caused the characteristic morphological change noted with ACTH. The extent of stimulation of steroidogenesis and the amount of inhibition of [(3)H]thymidine incorporation in response to various doses of ACTH were closely related and both were in parallel with the concentration of cyclic AMP in the cells. Cyclic GMP and cyclic IMP did not inhibit [(3)H]thymidine incorporation significantly, and did not change the morphology of the cells. AMP inhibited [(3)H]thymidine incorporation into DNA and caused the characteristic morphological change. However, AMP did not increase the cyclic AMP content of the cells. CMP, GMP, and UMP showed a significant inhibition of [(3)H]thymidine incorporation into DNA, but the extent of the inhibition was much less than that with AMP. These nucleotides did not change the morphology of the cells.

Adrenal Gland Neoplasms↗
PubMed1971

Role of the receptor in the mechanism of action of adenosine 3':5'-cyclic monophosphate.

Highly purified cAMP-dependent protein phosphokinase from adrenal-cortical tissue contains cAMP-receptor activity. In activating the kinase, cAMP binds to the receptor and causes it to dissociate from its complex with the kinase. The kinase, freed of receptor, is fully activated and no longer stimulable by cAMP. Kinase can be similarly activated by differentially denaturing the receptor with heat. Addition of receptor suppresses kinase activity; this suppression can be overcome by cAMP. After dissociation of receptor, two molecular forms of the activated kinase exist. The cAMP receptor thus functions as a repressor of the protein kinase; binding of cAMP to receptor causes it to dissociate from the kinase, which is then fully activated.

Adenine Nucleotides↗
PubMed1971

Phosphorylation of ribosome-associated protein by an adenosine 3':5'-cyclic monophosphate-dependent protein kinase: location of the microsomal receptor and protein kinase.

In the adrenal cortex, the adenosine 3':5'-cyclic monophosphate (cAMP)-receptor protein and the cAMP-dependent protein kinase are located in both the cytosol and endoplasmic reticulum. The cAMP-dependent protein kinase from the cytosol catalyzes the phosphorylation of ribosome-associated protein. Ribosomes washed in 0.5 M NH(4)Cl retain the substrate of the protein kinase reaction, but are dependent on the NH(4)Cl extract for in vitro protein synthesis. Dissociation of the 80S ribosomes by 0.88 M KCl, however, releases the ribosome-associated (protein) substrate of the phosphorylation reaction.

Adenine Nucleotides↗