Splicing patterns of type XI collagen transcripts act as molecular markers for osteochondrogenic tumors

Primary transcripts for three distinct alpha chains of the type XI collagen molecule (alpha1(XI), alpha2(XI) and alpha3[XI]) undergo tissue-specific alternative splicing during the process of osteochondrogenesis. In the present study, we analyzed the splicing patterns of type XI collagen genes in osteochondrogenic tumors as well as in various normal tissues using the reverse transcription-polymerase chain reaction method. Analysis of normal subjects revealed the coordinated expression of short alpha1(XI), alpha2(XI) and alpha3(XI) transcripts in the normal differentiated cartilage. Osteochondroma followed this pattern, reflecting the highly chondrogenic phenotype of this benign tumor. Another benign tumor, chondroblastoma, exclusively expressed the long alpha1(XI) transcript, probably reflecting the lack of a chondrogenic nature. Among malignant chondrogenic tumors, the splicing patterns of type XI collagen transcripts were more complex, showing dissociated expression of long alpha1(XI) and short alpha2(XI) mRNAs. This expression pattern may reflect heterogeneous cell populations and may also reflect various levels of cell differentiation in malignant tumors. In addition, short alpha3(XI) expression switched to the long transcript as chondrosarcomas became more aggressive. Thus, the alternative splicing of type XI collagen genes seems to be oncodevelopmentally regulated and splicing analysis may therefore be a useful marker for chondrogenic tumors.

SYT-SSX fusion proteins in synovial sarcomas: detection and characterization with new antibodies

To identify and characterize the SYT-SSX fusion proteins in synovial sarcomas, we developed two polyclonal antibodies against the N-terminal part and for the C-terminal part of the SYT-SSX2 protein. Specificity was demonstrated on COS-7 cells transfected with two subtypes of SYT-SSX fusion genes, SYT-SSX1 and SYT-SSX2. Both antibodies recognized a single protein of 61 kDa in an immunoprecipitation of the transfected COS-7 cell lysates. These antibodies also detected the native protein of 61 kDa in the lysate of a human synovial sarcoma cell line (HS-SY41) with immunoprecipitation, and in extracts of human synovial sarcomas with western blot analysis. An immunohistochemical study, using human synovial sarcoma tissues, demonstrated that the SYT-SSX fusion proteins localized in the nucleus of the tumor cells. These antibodies provide a useful method for studying the expression of the SYT-SSX fusion proteins.

Correlation of in vivo nitric oxide and cGMP with glutamate/glutamine metabolism in the rat striatum

We have examined how the suppression of endogenous production of nitric oxide (NO) in the striatal tissue affects release of glutamate (GLU) and glutamine (GLN) in pentobarbital-anesthetized male Sprague-Dawley rats. For the quantitative measurement of tissue NO production and amino acid release, an in vivo assay system for extracellular nitrite (NO2-) and amino acids was employed using an in vivo microdialysis technique. An NO synthase inhibitor (NG-nitro-L-arginine methyl ester, L-NAME) in concentrations ranging between 4-40 mM was perfused into the rat striatum using the assay system. Tissue NO production was found to be inversely proportional to the L-NAME concentration. L-NAME likewise decreased striatal levels of GLU and GLN. Furthermore, tissue NO production showed a positive correlation with GLU (R = 0.62, P < 0.02) and GLN (R = 0.86, P < 0.001) concentrations. Exogenous application of NO and cGMP by intrastriatal perfusion with 0.1-2.5 mM hydroxylamine and 0.4-10 mM 8-bromo-cGMP, respectively, increased striatal GLU release in a dose-related manner. Hydroxylamine reduced GLN release, and 8-bromo-cGMP showed a tendency to decrease GLN. In conclusion, striatal GLU/GLN metabolism is a function of the tissue concentration of NO. Normal endogenous concentration of NO causes GLU to be released at a consistent basal level, and enhanced tissue NO production facilitates GLU release via pathways including cGMP formation. We hypothesize that NO may suppress GLN formation by astrocytes.

Soft-tissue osteochondroma in the calcaneal pad: a case report

Soft-tissue osteochondromas of the foot are infrequently occurring lesions. A 65-year-old woman presented with soft-tissue osteochondroma in the soft tissues superficial to the plantar aspect of the calcaneus. The mass was densely ossified without cortical destruction or other alteration in the adjacent calcaneal bone on x-rays and computed tomography images. A 99m Tc bone scan showed a focal area of an increased uptake at the site of the mass below the calcaneus. Magnetic resonance imaging demonstrated high signal mass on T1-weighted images, isointense to fatty marrow, adjacent to the thickened plantar aponeurosis. The mass was completely excised. Histologically, mature lamellar bone was seen centrally, and the periphery was capped with hyaline cartilage. Since the tumor was located in the plantar aponeurosis and comprised of a single nodule of well-developed bone with well-organized endochondral ossification, the pathogenesis of this lesion might be related to metaplasia.

Comparative analyses of isoforms of the calcium-independent phosphatidylethanolamine N-acyltransferase PLAAT-1 in humans and mice

N-Acylphosphatidylethanolamines (NAPEs) are a class of glycerophospholipids, which are known as precursors for different bioactive N-acylethanolamines. We previously reported that phospholipase A/acyltransferase-1 (PLAAT-1), which was originally found in mammals as a tumor suppressor, catalyzes N-acylation of phosphatidylethanolamines to form NAPEs. However, recent online database suggested the presence of an uncharacterized isoform of PLAAT-1 with an extra sequence at the N terminus. In the present study, we examined the occurrence, intracellular localization, and catalytic properties of this longer isoform, as well as the original shorter isoform from humans and mice. Our results showed that human tissues express the longer isoform but not the short isoform at all. In contrast, mice expressed both isoforms with different tissue distribution. Unlike the cytoplasmic localization of the shorter isoform, the long isoform was found in both cytoplasm and nucleus, inferring that the extra sequence harbors a nuclear localization signal. As assayed with purified proteins, neither isoform required calcium for full activity. Moreover, the overexpression of each isoform remarkably increased cellular NAPE levels. These results conclude that the new long isoform of PLAAT-1 is a calcium-independent N-acyltransferase existing in both cytoplasm and nucleus and suggest a possible formation of NAPEs in various membrane structures including nuclear membrane. J. Lipid Res 2016. 57: 2051-2060.

The distribution of cathepsin D in two types of lysosomal or endosomal profiles of rat hepatocytes as revealed by combined immunocytochemistry and acid phosphatase enzyme cytochemistry

In the electron micrographs of rat hepatocytes, acid phosphatase (ACPase)-positive profiles were classified as either round or elongate types by image analysis, according to a shape index. The former is typical of spherical lysosomes, and the latter are presumed to be the same structures that we have previously termed nematolysosomes. The localization of cathepsin D in these two types of ACPase-positive profiles was electron microscopically examined by a combination of enzyme cytochemistry for ACPase and postembedding immunocytochemistry for cathepsin D. Gold particles showing antigenic sites for cathepsin D were largely present in ACPase-positive structures, although the labeling intensity of gold particles varied with individual sectional profiles of these structures. Quantitative analysis of the labeling density in the two types of ACPase-positive profiles revealed that the amount of cathepsin D in the elongate-type population was smaller than that in the round-type one. This result suggests that the contents of most elongate ACPase-positive structures are different from those of spherical lysosomes and may be similar to those of endosomes. It was also frequently observed that some of the elongate ACPase-positive profiles labeled with few or no gold particles were fused with round profiles which were heavily labeled with gold particles for cathepsin D. It is possible that such fused profiles may be sites for junctions of the two different transport pathways for ACPase and cathepsin D being delivered to lysosomes. Finally, these elongate ACPase-positive structures seem to be equivalent to late endosomes or a different kind of lysosomes containing lower concentrations of hydrolases.

Changes of microbial characteristics of retained sludge during low-temperature operation of an EGSB reactor for low-strength wastewater treatment

In this study, a lab scale EGSB reactor was operated for 400 days to investigate the influence of temperature-decrease on the microbial characteristic of retained sludge. The EGSB reactor was started-up at 15 degrees C seeding with 20 degrees C-grown granular sludge. The influent COD of synthetic wastewater was set at 0.6-0.8 gCOD/L. The process-temperature was stepwise reduced from 15 degrees C to 5 degrees C during 400 days operation. Decrease of temperature of the reactor from 15 degrees C to 10 degrees C caused the decline of COD removal efficiency. However, continuous operation of the EGSB reactor led the efficient treatment of wastewater (70% of COD removal, 50% of methane recovery) at 10 degrees C. We confirmed that the both acetate-fed and hydrogen-fed methanogenic activities of retained sludge clearly increased under 15 to 20 degrees C. Changes of microbial profiles of methanogenic bacteria were analyzed by 16S rDNA-targeted DGGE analysis and cloning. It shows that genus Methanospirillum as hydrogen-utilizing methanogen proliferated due to low temperature operation of the reactor. On the other hand, genus Methanosaeta presented in abundance as acetoclastic-methanogen throughout the experiment.

Intramuscular haemangioma adjacent to the bone surface with periosteal reaction. Report of three cases and review of the literature

We present three cases of intramuscular haemangioma adjacent to bone in the lower limb. All patients had local pain during the third decade. Plain radiographs showed an irregular or hypertrophic periosteal reaction on the shaft of the fibula and an intramuscular mass adjacent to the bone with inhomogeneous high signal intensity on MRI. These lesions mimic periosteal or parosteal tumours.

Anti-HLA antibody screening with extracted platelet HLA antigens by the mixed passive hemagglutination method

For the detection of anti-HLA antibody in the serum of patients receiving frequent platelet transfusions, we developed a new method in which platelet antigens are extracted into physiological saline containing 3% sucrose and coated as a layer on a U-type Terasaki plate. In the present study, screening of anti-HLA antibodies was conducted with this plate by the mixed passive hemagglutination test although the plate contained both HLA and HPA. The reactivity determined by this method correlated well with antihuman immunoglobulin-lymphocyte cytotoxicity test (AHG-LCT) results (r = 0.963). The plate can be preserved for at least 2 years at -80 degrees C and is easier to handle than the frozen lymphocyte panels used in the LCT test in which lymphocytes must be kept alive. This new method is an alternative way to screen HLA antibodies. In addition, it is expected that this method will be used to screen anti-HPA antibodies.

Development of an automated fluorescence microscopy system for photomanipulation of genetically encoded photoactivatable proteins (optogenetics) in live cells

Photomanipulation of genetically encoded light-sensitive protein activity, also known as optogenetics, is one of the most innovative recent microscopy techniques in the fields of cell biology and neurobiology. Although photomanipulation is usually performed by diverting the photobleaching mode of a confocal laser microscope, photobleaching by the laser scanning unit is not always suitable for photoactivation. We have developed a simple automated wide-field fluorescence microscopy system for the photomanipulation of genetically encoded photoactivatable proteins in live cells. An electrically automated fluorescence microscope can be controlled through MetaMorph imaging software, making it possible to acquire time-lapse, multiwavelength images of live cells. Using the journal (macro recording) function of MetaMorph, we wrote a macro program to change the excitation filter for photoactivation and illumination area during the intervals of image acquisition. When this program was run on the wide-field fluorescence microscope, cells expressing genetically encoded photoactivatable Rac1, which is activated under blue light, showed morphological changes such as lamellipodial extension and cell surface ruffling in the illuminated region. Using software-based development, we successfully constructed a fully automated photoactivation microscopy system for a mercury lamp-based fluorescence microscope.

Extended HLA haplotypes in Japanese homozygous typing cells

We have defined extended HLA haplotypes including the HLA class II genes, the non-HLA genes such as TAP1, TAP2 and LMP2, and the (CTG)n microsatellite repeats within the NOTCH4 gene between DRA and 21OH in 33 Japanese HLA homozygous typing cells (HTC). These conserved haplotypes characterized by unique linkage might be maintained as a result of functional co-operation among them in the antigen presentation pathway. These HTCs can be served as an original and ethnic-specific standard panel, providing useful genetic markers in haplotypic diversity, disease association, and anthropology studies.

PALETTE: A randomized, double-blind, phase III trial of pazopanib versus placebo in patients (pts) with soft-tissue sarcoma (STS) whose disease has progressed during or following prior chemotherapy—An EORTC STBSG Global Network Study (EORTC 62072)

LBA10002

Background: Pazopanib, a multi targeted angiogenesis inhibitor, has demonstrated single-agent activity in pts with advanced STS. The efficacy and safety of pazopanib versus placebo as second or later line treatment were evaluated in pts with metastatic STS in a multi-center, international, double-blind, placebo-controlled phase III trial. Methods: Pts ≥18 years of age with angiogenesis inhibitor-naïve, histologically proven, metastatic STS, who failed at least one anthracycline containing regimen, could enter the study. They should have ≥1 measurable baseline lesion (per RECIST v1.0), WHO PS 0-1, adequate bone marrow, coagulation, hepatic and renal function, no poorly controlled hypertension, no bleeding diathesis, and no CNS involvement. The study has been conducted by EORTC and GSK in collaboration with 72 sarcoma centers worldwide. Pts were randomized 2:1 to receive either pazopanib 800 mg once daily or placebo until tumor progression, unacceptable toxicity, death, or pt’s request. Results: A total of 369 randomized pts (246 pazopanib, 123 placebo), median age of 56 years, participated in the study (EORTC 45 %, other 55%). Median duration of follow-up at clinical cut-off date is 15 months. The primary endpoint of progression-free survival (PFS) per independent review is significantly prolonged with pazopanib (median: 20 vs 7 weeks; HR=0.31, 95% CI 0.24-0.40 ; P<0.0001). The interim analysis for overall survival shows a statistically non-significant improvement of pazopanib vs placebo (median: 11.9 vs 10.4 months, HR=0.83, 95% CI 0.62-1.09). Main on-therapy grade 3-4 toxicities in the pazopanib vs placebo arm respectively: fatigue (13%, 6%), hypertension (7%, nil), anorexia (6%, nil), and diarrhea (5%, 1%). Similarly, thromboembolic events (grade 3-5 ) (3%, 2%), LVEF drop of >15% (8%, 3%). Median relative dose intensity of pazopanib was 768 mg daily. Conclusions: Pazopanib is an active drug in anthracycline pretreated metastatic STS pts with an increase in median PFS of 13 weeks.

Cytochemical demonstration of NPPase activity for detecting proton-translocating ATPase of Golgi complex in rat pancreatic acinar cells

An attempt at cytochemical demonstration of acidification proton-translocating ATPase (H(+)-ATPase) of Golgi complex in rat pancreatic acinar cells has been made by using p-nitrophenylphosphatase (NPPase) cytochemistry which is used for detecting of Na(+)-K(+)-ATPase (Mayahara et al. 1980) and gastric H(+)-K(+)-ATPase (Fujimoto et al. 1986). K(+)-independent NPPase activity was observed on the membrane of the trans cisternae of Golgi complex, but not inside of cisternae. The localization of NPPase activity is different from that of acid phosphatase activity where reaction products were seen on the inside of the trans Golgi cisternae. Since this activity was insensitive to vanadate, ouabain and independent of potassium ions, it was distinct from plasma membranous ATPases such as Na(+)-K(+)-ATPase and Ca2(+)-ATPase. The K(+)-independent NPPase activity was diminished by the inhibitors of H(+)-ATPase such as N-ethylmaleimide (NEM) and 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS). The NPPase reaction products were also seen on the membranes of other acidic organelles, i.e., lysosomes, endosomes, autophagosomes and coated vesicles. These results suggest that NPPase activity on the membrane of the Golgi complex and other acidic organelles corresponds with H(+)-ATPase which plays a role in acidification.

Ultracytochemistry of calmodulin binding sites in myocardial cells by staining of frozen thin sections with colloidal gold-labeled calmodulin

Calmodulin (CaM) has been implicated as a multifunctional regulator of Ca2+ in the cytoplasm of cells. We have recently introduced biologically active colloidal gold-labeled CaM as a marker for identifying potential CaM binding sites (unoccupied by endogenous CaM at the time of fixation) by electron microscopy and have stained frozen thin sections of rat cardiac muscle with this conjugate. In the presence of Ca2+, gold particles indicating CaM binding sites were found localized on the sarcoplasmic reticulum, mitochondria, and gap junctions. Control tissue sections treated with EGTA or exposed to excess amounts of unlabeled native CaM before staining showed no binding. We believe that cytochemistry of potential CaM binding sites revealed by staining with labeled exogenous CaM is useful in correlating known biochemical reactions of CaM with particular cell activities.

Evaluation of glass microspheres for intra-arterial radiotherapy in animal kidneys

PURPOSE

To evaluate the histologic distribution of nonradioactive microspheres when intra-arterially infused into normal kidneys, and to evaluate the histologic changes after the infusion.

MATERIALS AND METHODS

The glass microspheres were SiO2 microspheres with a smooth spherical shape measuring 20-30 micrometers in diameter with a specific gravity of 2.2 g/cm3. After the microspheres were mixed with contrast medium, they were infused into the renal artery. Twelve rabbits were sacrificed at 1 day, 3 days, 1 week, and 8 weeks after the treatment, respectively. The specimen was fixed with 10% buffered formalin, specially embedded in methyl methacrylate (MMA) resin and was stained by hematoxylin-eosin. The distribution of the microspheres in the kidney was analyzed microscopically, and histologic changes were also evaluated.

RESULTS

The microspheres were found in arterioles whose diameters were about 20-30 micrometers, within normal kidneys. All vessels containing microspheres were confined to arterioles or arteries. No migration of microspheres was detected in the normal lung or the contralateral kidney. Severe ischemic changes were observed in kidneys, developing within 8 weeks of the infusion.

CONCLUSION

Glass microspheres seemed to be a useful embolic material for intra-arterial radiation therapy.

Immunocytochemical analysis of cubilin-mediated endocytosis of high density lipoproteins (HDL) in epithelial cells of the rat visceral yolk sac

Cubilin was recently shown to function as an endocytic receptor for high density lipoprotein (HDL) holoparticles and apolipoprotein A-I (apo A-I), the main protein constituent of HDL. In the present study, we analyzed the distribution and intracellular trafficking of cubilin and HDL in rat visceral yolk sac epithelial cells. After epithelial cells were loaded with apolipoprotein E-free HDL for 30 min in vitro, double immunofluorescence showed that the apical cytoplasm of the cells was strongly stained with anti-cubilin antibodies and anti-apo A-I/HDL. Furthermore, double immunogold electron-microscopic observations revealed the distinct localization of cubilin and HDL in endocytic vacuoles. In early endosomes, both were colocalized on the membrane. Although, in late endosomes, cubilin was also localized on the membrane, HDL was mainly located in the matrix. Both were found in the matrix in lysosomes. In addition, cubilin was markedly localized in apical tubules (ATs), which are generally accepted as being receptor recycling compartments. Thus, HDL is internalized through cubilin-mediated endocytosis and is finally transported to lysosomes. By contrast, cubilin is mainly translocated to ATs for recycling, although some of the cubilin is degraded in lysosomes. Quantitative analysis further revealed that cubilin was not concentrated on the membranes of ATs, although it accumulated in the AT area. Some HDL were also observed in the AT area. These findings suggest that the translocation of cubilin and HDL to ATs from early endosomes occurs through a simple sorting mechanism based on the geometry of these compartments and the bulk membrane and volume flow.

Degranulation and shrinkage of dark cells in eccrine glands and elevated serum carcinoembryonic antigen in patients with acquired idiopathic generalized anhidrosis

BACKGROUND

Acquired idiopathic generalized anhidrosis (AIGA) is characterized by anhidrosis/hypohidrosis without other autonomic and neurological dysfunctions. Pathologically, AIGA is considered to usually present no significant morphological alterations in eccrine glands, the secretory portion which consists of clear cells, dark cells, and myoepithelial cells. AIGA patients recently have been reported to show high serum concentrations of carcinoembryonic antigen (CEA).

OBJECTIVE

Our aim is to reveal morphological abnormalities of dark cells and investigate their relationship with serum CEA.

METHODS

We performed comparative analysis of eccrine glands between sweat-preserved and non-sweating skin in four AIGA patients. Serum CEA concentrations in 22 cases with AIGA were measured with healthy volunteers. Furthermore, we semiquantitatively investigated dermcidin, FoxA1 and CEA expression in eccrine glands of 12 cases with AIGA and 5 cases with non-AIGA.

RESULTS

Marked degranulation and shrinkage of dark cells consistently occurred in AIGA. Furthermore, high serum CEA concentrations were found in 14 of 22 AIGA patients (over 60%), but serum CEA levels were not correlated with CEA expression in eccrine glands. Dermcidin expression in dark cells apparently decreased in AIGA patients, severely in those with high serum CEA and moderately in those with low serum CEA, while well-preserved expression was found in non-AIGA subjects.

CONCLUSION

Our study suggests morphological damage and molecular dysregulation of dark cells, leading to impairment of their functions in AIGA patients. Severely damaged dark cells correspond to high serum CEA. Accordingly, these pathological changes in eccrine dark cells may be involved in anhidrosis/hypohidrosis of AIGA.

Soluble megalin is accumulated in the lumen of the rat endolymphatic sac

The endolymphatic sac (ES) is believed to play an important role in maintaining homeostasis in the inner ear by the absorption and endocytosis of endolymph. Megalin is a 600-kDa multiligand endocytic receptor expressed in certain types of absorptive epithelia including kidney proximal tubules. We analyzed the immunoreactivity for megalin in rat ES by immunofluorescence, immunogold electron microscopy, and immunoblotting. With immunostaining, the luminal substances of the ES were strongly stained for megalin. Megalin was also localized in luminal macrophage-like cells and both types of epithelial cell (mitochondria-rich cells and ribosome-rich cells). In these cells, the megalin was localized in the lumen of endosomes, but was not membrane associated. This localization pattern indicates that the megalin in these cells is not a membrane receptor, but merely one of the constituents that are endocytosed from the lumen of the ES. Immunoblotting indicated that the megalin in the ES is a 210-kDa molecule lacking a cytoplasmic domain. This suggests that the megalin in the ES may be a soluble form, different from the 600-kDa membrane-bound receptor expressed in kidneys. Taken together, it is likely that the megalin in the ES lumen is a soluble component and may be endocytosed by the ES epithelial cells. Furthermore, we found that the tectorial membrane, an acellular structure in the cochlea, gave a strong megalin immunoreaction. Since the cochlea is connected to the ES, the megalin may be transported alone or with the components of the tectorial membrane from the cochlea to the ES lumen through longitudinal flow.

The role of intracellular anionic phospholipids in the production of N-acyl-phosphatidylethanolamines by cytosolic phospholipase A2ɛ

N-Acyl-phosphatidylethanolamines (NAPEs) represent a class of glycerophospholipids and serve as the precursors of bioactive N-acylethanolamines, including arachidonoylethanolamide (anandamide), palmitoylethanolamide and oleoylethanolamide. NAPEs are produced in mammals by N-acyltransferases, the enzymes which transfer an acyl chain of glycerophospholipids to the amino group of phosphatidylethanolamine. Recently, the ɛ isoform of cytosolic phospholipase A2 (cPLA2ɛ, also called PLA2G4E) was identified as Ca2+-dependent N-acyltransferase. We showed that the activity is remarkably stimulated by phosphatidylserine (PS) in vitro. In the present study, we investigated whether or not endogenous PS regulates the function of cPLA2ɛ in living cells. When PS synthesis was suppressed by the knockdown of PS synthases in cPLA2ɛ-expressing cells, the cPLA2ɛ level and its N-acyltransferase activity were significantly reduced. Mutagenesis studies revealed that all of C2, lipase and polybasic domains of cPLA2ɛ were required for its proper localization as well as the enzyme activity. Liposome-based assays showed that several anionic glycerophospholipids, including PS, phosphatidic acid and phosphatidylinositol 4,5-bisphosphate, enhance the Ca2+-dependent binding of purified cPLA2ɛ to liposome membrane and stimulate its N-acyltransferase activity. Altogether, these results suggested that endogenous PS and other anionic phospholipids affect the localization and enzyme activity of cPLA2ɛ.

Effects of parathyroid hormone in vivo on the protein kinase activity in rat kidney

Parathyroid hormone (PTH) was infused into thyroparathyroidectomized rats, and the protein kinase activity of the kidney was studied. When the tissue was homogenized in a buffer containing 5 mM potassium phosphate (pH 7.0), 2 mM EDTA, 1 mM mercaptoethanol, and 5 mM theophylline, the total protein kinase activity (measured in the presence of 5 muM cAMP) in the cytosol was decreased by the infusion of PTH, exhibiting an inverse relationship to cAMP level in the renal tissue. The decrease of total activity was accounted for by a decrease of cAMP-dependent kinase activity, and such a change was induced also by the infusion of calcitonin or dibutyryl cAMP. A substantial enzyme activity was solubilized from the particulate fraction with a buffer containing KC1. The infusion of PTH increased the kinase activity (activities measured in both the presence and absence of cAMP) solubilized from the particulate fraction, suggesting the translocation of activated enzyme from cytosol to some particulate cell component(s). However, when KC1 was added to the homogenization buffer in concentrations up to 150 mM or even higher, the total protein kianse activities in the cytosols of control and PTH rats were similar and there was simply an increase in the fraction of cAMP -independent activity. These observations indicate that the hormonally-induced increase of cAMP in vivo activates protein kinase of the kidney, and the activation of kinase results in apparent translocation of the enzyme from the soluble to the particulate fraction when the tissue is homogenized in buffers of low ionic strength. The physiological significance of this phenomenon, however, cannot be evaluated, due to the fact that the increased association of activated kinase with particulate component(s) is reversed by employing a homogenization buffer containing what is probably a physiological concentration of salt.