Nucleoplasmin associates with and is phosphorylated by casein kinase II

Nucleoplasmin is a phosphorylated nuclear-accumulating protein. We report herein that the kinetics of its cytoplasm-->nucleus transport are affected by its degree of phosphorylation. Therefore, we sought to identify any protein kinase which specifically associates with nucleoplasmin. We discovered that nucleoplasmin co-isolates by two independent methods (immunoabsorption and chromatography) in a complex including a kinase which phosphorylates nucleoplasmin. The co-purifying kinase is casein kinase II-like because: (i) it phosphorylates casein; (ii) its phospho-transferase activity can be competed out by GTP; (iii) it is stimulated by polylysine; and (iv) it is inhibited by heparin. Moreover, a polyclonal antibody to the alpha (38 kDa) and alpha' (36 kDa) catalytic subunits of casein kinase II specifically recognizes 38 and 36 kDa polypeptides in the nucleoplasmin-complex, and a specific inhibitor of casein kinase II inhibits nucleoplasmin's nuclear transport. Additionally, we found that phosphorylation of nucleoplasmin by its associated casein kinase II is strongly inhibited by histones and that, in addition to nucleoplasmin, another protein (p100) in the nucleoplasmin-complex is phosphorylated by casein kinase II.

An NLS is sufficient to engage facilitated translocation by the nuclear pore complex and subsequent intranuclear binding

We investigated the nuclear transport of a fusion protein consisting of a nuclear localization signal linked to beta-galactosidase, normally a cytoplasmic protein. We microinjected the radiolabeled fusion protein into the cytoplasm of living Xenopus oocytes or supplied it directly to the surface of the oil-isolated oocyte nucleus and measured its transport into the nucleus. Our data confirm that a nuclear localization signal is sufficient to entrain a protein's facilitated transport through the nuclear pore complex and its subsequent nuclear accumulation. Moreover, nuclear envelope micropuncture experiments determine that the fusion protein's accumulation results from its intranuclear binding, demonstrating that no specific region of a transported protein--other than the nuclear localization signal itself--is required for facilitated transport and intranuclear binding. Finally, we present evidence that the intranuclear binding of a transported protein requires not only its nuclear localization signal, but also its prior facilitated transport through the nuclear pore complex.

Decline of serum cobalamin levels with increasing age among geriatric outpatients

The level of serum cobalamin declines with increasing age. Among 100 consecutive geriatric outpatients who were seen in office-based settings for various acute and chronic medical illnesses but not for cobalamin deficiency-related diseases, 11% had serum cobalamin levels from 148 to 295 pmol/L. The average annual serum cobalamin level decline was 18 pmol/L for patients who had higher initial serum cobalamin levels (actual range, from 224 to 292 pmol/L). The average annual serum cobalamin decline was 28 pmol/L, which was much higher, for patients who had lower initial serum cobalamin levels (actual range, from 157 to 221 pmol/L). Patients with initial serum cobalamin levels of 148 pmol/L or below received treatment immediately, and their declines could not be studied.

[Preliminary observation on the detection of schistosome circulating antigen and the immunocomplex by dot-ELISA]

Serum samples were collected from normal rabbits, normal persons, Schistosoma japonicum-infected rabbits and human cases respectively, and were treated by TCA precipitation and PEG precipitation, and subsequently detected by dot-ELISA. The results showed that both the supernatants of TCA-treated antisera from infected human cases and rabbits and the precipitants of PEG-treated antisera of the same origins showed positive reactions, while no positive reactions were found for sera from normal rabbits and normal persons. It was exhibited that dot-ELISA detected not only the circulating antigen of schistosomes but also the immunocomplex.

[Hair cell damage and regeneration in the quail cochlea following kanamycin ototoxicity]

Forty-day old quails were given kanamycin (KM) at a dose of 400mg/kg per day for ten days. Evoked potential thresholds induced by both click and tone burst were obtained at 1 day or 1, 2, 3, 4 and 6 weeks respectively after the last injection, and compared with the thresholds of age-matched control animals. The cochlea of the animals was examined by scanning electron microscopy (SEM). The results showed that the application of KM for 10 days produced massive destruction of the basilar papilla at 1 day posttreatment. The damaged region began at the base and extended apically to the position about 50-70% of the total distance along the papilla, with most severe damage in the basal end. The auditory thresholds measured at the same time revealed a significant elevation at 2 and 4 kHz. However, the number of hair cells in the damaged region recovered rapidly with time, and so did the function. By the end of 3 weeks postinjection, almost all the hair cells reappeared in the pathologic region and the function improved further, with nearly normal thresholds at all frequencies but 4kHz. Six weeks after KM treatment, the basilar papilla showed a nearly normal appearance, but there was no further functional improvement at 4kHz, with the threshold shift by 17.5 dB (P < 0.01). The results of the present study demonstrated that structural recovery was faster than functional one.

Nucleoplasmin uptake by facilitated transport and intranuclear binding

Specific proteins are selectively translocated into the cell nucleus and accumulated therein, but the molecular mechanisms underlying this fundamental eukaryotic transport process remain obscure. We have employed a new experimental system with notable advantages for resolving protein translocation and accumulation mechanisms. Individual nuclei are isolated from oocytes under mineral oil and conjoined under the oil with either an aqueous bead or a similar volume of oocyte cytoplasm to form closed transport pairs. Using these pairs one can (i) present transportant proteins via the bead or cytoplasm to a minimally disturbed nucleus, (ii) monitor the intactness of the nuclear envelope, and (iii) separate pairs at various times after formation and measure the amount of transportant in each compartment. In addition, it is uniquely possible with these pairs to determine whether or not a transportant's concentration gradient constitutes a chemical activity gradient. This is done by puncturing the envelope, thus eliminating its normal sieving restrictions on diffusion, and measuring the effect on the transportant distributions. We demonstrate that a prototypical nuclear-accumulating protein, nucleoplasmin (Np), is translocated through the nuclear pore complex by a mechanism of facilitated transport, rather than active transport. We further show that Np's high accumulation results from subsequent intranuclear binding. Np's facilitated transport and intranuclear binding are both ATP-dependent, and the latter requires cytoplasmic protein(s).

A DNA-activated protein kinase from HeLa cell nuclei

A DNA-activated protein kinase (DNA-PK) was purified from nuclei of HeLa cells. Activity was associated with a single high-molecular-mass (approximately-300,000 Da) polypeptide when analyzed by gel filtration, denaturing polyacrylamide gel electrophoresis, and Western immunoblotting using a monoclonal antibody that also inhibits enzyme activity. Nuclear localization was indicated by subcellular fractionation and confirmed by immunofluorescence on whole cells. Double-stranded DNA stimulated phosphorylation of the 300-kDa polypeptide in purified preparations as well as phosphorylation of the exogenous substrates alpha-casein, simian virus 40 large T antigen, and the human heat shock protein hsp90. Autophosphorylation led to inactivation of the enzyme. The phosphorylation of casein was stimulated over 30-fold by DNA and was specific for serine and threonine residues. Bovine serum albumin and histone H1 were poor substrates for DNA-PK, and no phosphorylation of immunoglobulin G or histones other than H1 was observed. Supercoiled or heat-denatured DNA and synthetic double-stranded RNA or RNA-DNA copolymers did not stimulate casein phosphorylation by DNA-PK. Interaction of the enzyme with DNA in the absence of exogenous substrates was demonstrated by thermal inactivation and gel mobility shifts. These characteristics identify DNA-PK as distinct from other protein kinases described in the literature and suggest that activation by DNA is an important feature of the enzyme's in vivo function.

[Pleural effusion indicator of pancreatitis]

The presence of a pleural effusion in patients with pancreatitis is a common marginal occurrence. On rare occasions the pleural effusion not only is abundant, recurrent, hemorrhagic and contains a high concentration of amylase, but presents as the only manifestation of an otherwise undiagnosed or obscure pancreatitis. Thus it presents a difficult diagnostic and therapeutic problem. The authors report such a case and review the literature in which 49 cases have been reported in the past 10 years. Pancreatomediastinopleural fistula is usually visualized and seems to be the basic fault in most cases. Thoracic drainage will relieve the patient and dry up the effusion in one third of cases. Otherwise pancreatic resection is usually required. Internal or external drainage of the mediastinopleural component by laparotomy is not difficult. Pleural sequelae are minimal in most cases.

Experience with hyperselective vagotomy in patients with duodenal ulcer

Hyperselective vagotomy is a relatively recent surgical procedure used for the treatment of duodenal ulcer. We report excellent results in 98 consecutive patients during the last four years. After a mean follow-up period of 2.2 years, the results, according to the classification of Visick, are excellent in a large number of patients. There was a significant gain in body weight in a majority of the patients. The recurrence rate for an ulcer is only 4.5 per cent. There is a significant reduction of basal acid output of 63 per cent, maximal acid output of 46.8 per cent and postinsulin acid output of 73.7 per cent.