Enhanced template activity in chromatin from adrenal medulla after phosphorylation of chromosomal proteins

Changes in the chromatin of the brain of developing rats: phosphorylation of chromosomal proteins and modulation of transcription

In vitro phosphorylation of chromosomal proteins and transcription of chromatin, and their modulation by spermine were studied by incubating slices of cerebral cortex of 3-30 day old developing rats with [32Pi] and [3H]-uridine, respectively. Phosphorylation of histones increases whereas that of nonhistone chromosomal (NHC) proteins decreases during development. Spermine stimulates phosphorylation of both histones and NHC proteins. Transcription of chromatin decreases as development progresses. Phosphorylation of chromosomal proteins stimulates transcription. This is further stimulated by spermine. However, these effects decrease as development proceeds. Such functional alterations in the chromatin may be responsible for the terminal differentiation of neurons, and may have a significant role in differential gene expression during cell differentiation and development.

A proposed model of cancer as the inappropriate expression of non-body introns

An a posteriori proposal is made that cancer represents an alien non-body phenotype erupting from "silent" gene groups within actively coding regions of a normal cell's genome. Relevant empirical data is garnered from the literature and twelve premises are derived from the data. On the basis of these premises it is hypothesized that the malignant neoplastic phenotype results from interference with non-histone chromosomal proteins causing retention and expression in a body cell of non-body introns. These are asserted to be the same introns which, as exons in a trophoblast cell, direct the normal development of the fetal placenta. Development of a malignant tumor is presented as a pathological recapitulation of the development of a normal placenta. Unrestrained tumor growth is attributed to the inability of endogenous body chalones to suppress the non-body gene groups coding for neoplastic mitosis, while invasion and metastasis result from failure of the non-body genes which code for implantation and mitosis to switch off at the proper time. The hypothesis asserts that all carcinogenic agents alter phosphorylation of non-histone chromosomal proteins, that cancer and normal trophoblast cells are genetically programmed to travel through the body's vascular system to effect immunosuppression in lymphoid tissues, that malignant neoplastic tissue will regress when exposed to trophoblast-based chalones, and that mammals immunized against trophoblast-based antigen will be resistant to the development of malignant tumors.

Specific nuclear binding of adenosine 3',5'-monophosphate-binding protein complex with subsequent poly(A) RNA synthesis in embryonic chick cartilage

We used embryonic chick pelvic cartilage as a model to study the mechanism by which cyclic AMP increases RNA synthesis. Isolated nuclei were incubated with [32P]-8-azidoadenosine 3,5'-monophosphate ([32P]N3cAMP) with no resultant specific nuclear binding. However, in the presence of cytosol proteins, nuclear binding of [32P]N3cAMP was demonstrable that was specific, time dependent, and dependent on a heat-labile cytosol factor. The possible biological significance of the nuclear binding of the cyclic AMP-protein complex was identified by incubating isolating nuclei with either cyclic AMP or cytosol cyclic AMP-binding proteins prepared by batch elution DEAE cellulose chromatography (DEAE peak cytosol protein), or both, in the presence of cold nucleotides and [3H]uridine 5'-triphosphate. Poly(A) RNA production occurred only in nuclei incubated with cyclic AMP and the DEAE peak cytosol protein preparation. Actinomycin D inhibited the incorporation of [3H]uridine 5'-monophosphate into poly(A) RNA. The newly synthesized poly(A) RNA had a sedimentation constant of 23S. Characterization of the cytosol cyclic AMP binding proteins using [32P]N3-cAMP with photoaffinity labeling three major cAMP-binding complexes (41,000, 51,000, and 55,000 daltons). The 51,000 and 55,000 dalton cyclic AMP binding proteins were further purified by DNA-cellulose chromatography. In the presence of cyclic AMP they stimulated poly(A) RNA synthesis in isolated nuclei. The 51,000-dalton cyclic AMP-binding protein was the predominant one that bound to the nuclei. While cyclic AMP-dependent protein kinsae activity was present in the cytosol and DEAE peak cytosol proteins, it was not present in the DNA-cellulose-bound, cyclic AMP-binding proteins. We conclude that one possible mechanism by which cyclic AMP increases RNA synthesis is by complexing to a 51,000-dalton cytosol cyclic AMP-binding protein and being subsequently translocated to the nucleus, where it is specifically bound and associated with induction of poly(A) RNA synthesis.

Thy-1 cell surface antigen on cloned cell lines of the rat and mouse: stimulation by cAMP and by butyrate

The level of the Thy-1 cell surface antigen on a number of established rat and mouse nerve cell lines can be stimulated by N6, O2'-dibutyryl adenosine 3':5'-cyclic monophosphoric acid (Bt2cAMP), in some cases up to the antigen level found in whole brain. On rat cell line BN1010-3, stimulation is also produced by phosphodiesterase inhibitors, adenosine 3':5'-cycle monophosphoric acid (cAMP) and its 8-bromo derivative, and L-isoproterenol. Hence, antigen elevation appears to occur via cAMP-related metabolism. It is not a consequence of morphological changes brought about by cAMP elevation in these cells, and is apparently independent of the inhibition of cell division by the nucleotide. Elevations of intracellular cAMP levels for at least one hour are needed to produce Thy-1 stimulation, after which an enhanced level of Thy-1 is observable after about 12 h. Continuous stimulation is required to maintain elevated antigen levels, for upon removal of the stimulating agent, the level of Thy-1 returns to the original unstimulated value within 48 h. Potent stimulation of the antigen level is also obtained with butyrate at 1--2 mM, which appears to be acting by a cAMP independent mechanism.

Translocation of cytosol protein kinase into nuclei and the induction of tyrosine hydroxylase in NBD-2 neuroblastoma cells

Exposure of neuroblastoma cells (NBD-2) to 8-bromo-adenosine 3',5'-cyclic monophosphate (0.2-1.0 mM) (8-Br-cAMP) for 15 min caused a long term increase in the Vmax of tyrosine-3-monooxygenase activity (TH) beginning about 1 day after 8-Br-cAMP application. Cyclic AMP-dependent histone kinase was maximally activated in about 30 min and stayed activated above pretreatment levels for one hour. In cells exposed to 8-Br-cAMP for 15 min, separation of soluble and particle bound histone kinase showed that the total histone kinase activity in the soluble fraction decreased by 40%. This decrease was accompanied by an increase in protein kinase activity in the particulate fraction, suggesting enzyme translocation. After translocation, the enzyme appears to acquire a different substrate affinity because it prefers as a PO43- acceptor, acidic protein rather than histone. In NBD-2 cells this kinase appears to precede, and may be related to, the delayed increase in TH Vmax.

Characterization of protein kinases from adrenal medulla. A study of cytosol and nuclear enzymes

Since phosphorylation of chromosomal proteins by cyclic AMP-dependent protein kinases (EC 2.7.1.37) enhances template activity of adrenal medulla chromatin (9), we have studied the properties and regulation of protein kinases isolated from chromaffin cell cytosol and nuclei. DEAE-cellulose chromatography revealed three peaks of kinase activity in the nucleus (nPKI, nPKII, nPKIII) and two in the cytosol (cPKI, cPKII). The three nuclear enzymes, as well as cPKII, did not require cyclic AMP to express their catalytic activity. nPKI and nPKIII preferred acidic substrates as PO3-4 acceptors, while nPKII and the cytosol enzymes preferred basic PO3-4 acceptors. Enzyme recombination experiments using protein kinase regulatory subunits from cytosol suggested that cPKII was the catalytic subunit of cPKI. In contrast, the nuclear enzymes were not catalytic subunits of the cyclic AMP-dependent protein kinase in the cytosol (cPKI). Only the cytosol protein kinases could be inhibited by endogenous heat-stable protein kinase inhibitors. The nuclear and cytosol cyclic AMP-independent protein kinases were distinguishable on the basis of their sedimentation constants as well as Mc2+ and Mn2+ requirements.

Alterations of macromolecule biosynthesis after chronic administration of opiates and ethanol

The literature concerning the effects of opiates, alcohol and barbiturates on RNA and protein metabolism is reviewed. Recent findings from this laboratory suggest that chronic morphine treatment increases the template activity of chromatin from oligodendroglial nuclei while chronic ethanol treatment decreases this activity. In addition, chronic morphine treatment stimulates protein synthesis in cell free systems and may increase the synthesis of discrete synaptic membrane proteins. Results from other laboratories suggest a general decrease in macromolecule biosynthesis with long term ethanol consumption. These results are discussed in terms of the possible roles of protein synthesis in the effects of chronic opiate and ethanol administration.

Association between the increase of cAMP content and the trans-synaptic induction of tyrosine hydroxylase in rat adrenal medulla. Studies with dexamethasone and reserpine

When dexamethasone 0.25 or 2.5 mumole/kg i.p. was injected 2 h before reserpine (16 mumol/kg i.p.) the time course of the increase in cAMP content of rat adrenal medulla was changed. Reserpine alone caused a monophasic increase lasting between 1-2 h; reserpine after dexamethasone caused a biphasic increase: the immediate response, lasting between 15 and 30 min, was followed by a secondary increase beginning 2-3 h after reserpine and lasting for several hours. The overall increase in cAMP content elicited by reserpine during the 8 h following injection remained unchanged or was even increased, depending on the dose of dexamethasone. Pretreatment with dexamethasone, which delayed the increase in cAMP, also delayed the activation and translocation of protein kinase and the induction of tyrosine hydroxylase caused by reserpine in adrenal medulla. The action of reserpine on the cAMP content of adrenal medulla required an intact innervation and did not appear to be related to increased secretion of ACTH from pituitary. In denervated adrenals reserpine failed to increase the cAMP content of the medulla but not that of the cortex.