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PubMed2026

Colocalization and functional analyses identify GBE1 as a gene linking muscle strength and cardiometabolic fitness.

Handgrip strength is a proxy for muscular fitness, an indicator for general health status, and is associated with cardiometabolic health. The mechanisms connecting handgrip strength to skeletal muscle function are incompletely understood. We applied integrated linkage-disequilibrium-adjusted colocalization analysis of genome-wide association study summary statistics for handgrip strength, combined with expression and splicing quantitative trait loci from skeletal muscle, and identified glycogen branching enzyme 1 (GBE1) as a candidate gene for handgrip strength. CRISPR-interference knockdown of GBE1 in immortalized human skeletal muscle cells (HMCL-7304) demonstrated decreased glycogen content and accumulation of polyglucosan bodies. Knockdown of GBE1 led to increased oxygen consumption rate, oxidative stress, and changes in mitochondrial morphology. Transcriptomic profiling of GBE1 knockdown cells identified upregulation of the human superoxide dismutase 2 and enrichment of pathways related to muscle contraction and oxidative stress responses. These functional genomic analyses prioritize GBE1 as a muscle-relevant candidate gene for handgrip strength and provide mechanistic insights to muscle fitness.NEW & NOTEWORTHY Colocalization of genome-wide association study (GWAS) loci with quantitative trait loci (QTL) in skeletal muscle tissue identified GBE1 as a candidate for handgrip strength. Cellular phenotypes with GBE1 knockdown in immortalized human skeletal muscle cells include decreased glycogen content, accumulation of polyglucosan bodies, changes in mitochondrial function and morphology, and increased expression of reactive oxygen species (ROS) scavengers. Transcriptomic changes suggest a role for GBE1 in muscle contraction and oxidative stress-mediated responses.

Humans↗

PubMed1992

Colocalization of GAPDH and band 3 (AE1) proteins in rat erythrocytes and kidney intercalated cell membranes.

Glyceraldehyde-3-phosphate dehydrogenase (EC 1.2.2.12) (GAPDH) is a multifunctional protein that associates with the cytoplasmic face of intact human erythrocyte membranes. This association has been postulated to be critically dependent on the interaction of GAPDH with the highly acidic NH2-terminal domain of the principal integral membrane protein of the erythrocyte plasma membrane, the band 3 anion exchanger (AE1). This domain is not conserved in murine erythrocyte AE1 and is fully deleted in the alternatively spliced AE1 isoform that is expressed in the kidney. The lack of conservation of this domain has been proposed to explain the reported absence of GAPDH association with rodent erythrocyte membranes. To determine whether GAPDH could be associated with AE1 proteins in rodent cell membranes, specific rabbit antibodies to peptide sequences of rat GAPDH and mouse AE1 were used to immunolocalize these proteins in sequential semithin sections of rat erythrocytes and kidney medulla. In rat erythrocytes, GAPDH immunoreactivity was predominantly membrane associated and colocalized with AE1. In the kidney medulla, GAPDH was concentrated in the basolateral membrane of type A intercalated cells, where it colocalized with the alternatively spliced kidney form of AE1. GAPDH immunoreactivity was not detected in the plasma membrane of any other cell type in the kidney, indicating its predominant association with AE1-rich membranes. If this membrane interaction occurs via AE1 binding, then GAPDH must have binding sites in addition to those previously described for such binding in human AE1.

Amino Acid Sequence↗

PubMed1991

Colocalization of delta sleep inducing peptide and luteinizing hormone releasing hormone in neurosecretory vesicles in rat median eminence.

The colocalization of immunoreactivities similar to delta sleep inducing peptide (DSIP) and luteinizing hormone releasing hormone (LH-RH) was investigated by light and electron microscopic immunocytochemistry in the rat median eminence. At the light microscopic level, DSIP and LH-RH immunostained fibers, and varicosities exhibited a similar distribution pattern throughout the median eminence. Immunoreactive axons were mainly found in the lateral part of the external layer. Using an elution-restaining technique, the coexistence of LH-RH and DSIP immunoreactivities was observed in most labelled axons. To determine the intracellular localization of DSIP and LH-RH, we used double immunocytochemical labelling with species-specific antibodies and secondary antibodies conjugated to different sizes of gold particles. The two peptides were found colocalized in single axons. Immunoreactive terminals frequently showed direct membrane apposition with tanycyte processes but rare contacts with portal capillaries. No staining was observed in tanycytes and ependymal or glial elements. Moreover, we could demonstrate that LH-RH and DSIP (or a closely related molecular form) are contained not only in the same axons, but also in the same approximately 100-nm dense-core vesicles, suggesting cosecretion of these peptides.

Animals↗

PubMed1991

Immunocytochemical localization of protein kinase-C subtypes in anterior pituitary cells: colocalization in hormone-containing cells reveals heterogeneity.

We have examined the distribution and colocalization of protein kinase-C (PKC) in cultured rat anterior pituitary cells by light microscopic immunocytochemistry using monoclonal antibodies to group A rat brain PKC subspecies. Type I (PKC gamma) was not detected in the cells, in line with the assertion that the gamma-enzyme is expressed specifically in central nervous tissues. The other subspecies recognized by the antibodies (PKC beta and PKC alpha) were present throughout the cytoplasm in a diffused pattern, while the nuclei were apparently unstained. The number of cells stained with the antibodies in juvenile animals (12 days old) increased rapidly with age and reached a plateau between adult (5-month-old) and older (1-yr-old) rats. Type II (PKC beta) was the predominant subspecies detected in anterior pituitary cells. Double immunofluorescence staining techniques enabled the colocalization of PKC with various anterior pituitary cell types. Surprisingly, not all of the hormone-producing cells were stained with the PKC antibodies. Moreover, within the different pituitary cell types, the percentage of PKC-stained cells varied, revealing heterogeneity among the various cell populations. Thus, among somatrophs, mammotrophs, thyrotrophs, ACTH-containing cells, and gonadotrophs, only 9%, 22%, 13%, 44%, and 26%, respectively, reacted with the PKC antibodies. We suggest that activation of pituitary PKC might mobilize only a fraction of the hormone-containing cells.

Animals↗

PubMed1992

Immunocytochemical colocalization of hypothalamic progestin receptors and tyrosine hydroxylase in steroid-treated monkeys.

Progesterone (P)-induced PRL secretion in estradiol (E)-primed monkeys is not due to direct pituitary stimulation, because lactotropes do not express progestin receptors (PR). However, the hypothalamus, particularly the tuberoinfundibular dopaminergic system (TIDA), plays a major role in the regulation of PRL secretion. To determine whether hypothalamic dopamine neurons are progestin target cells, the colocalization of PR and tyrosine hydroxylase (TH), a phenotypic marker of dopaminergic neurons, was examined with double immunocytochemistry. Two methods for visualizing the antigens were applied; the first was a dual peroxidase method, and the second was a peroxidase-alkaline phosphatase method. In addition, the question of whether E induces PR in dopamine neurons was explored. Spayed female monkeys were treated with empty Silastic capsules, E-filled capsules for a period of 28 days, or E capsules supplemented with P capsules for the last 14 days of E treatment. Only the E- plus P-treated monkeys exhibited an increase in serum PRL during the P treatment period. Frontal sections at the level of the optic chiasm and arcuate nucleus were examined for the colocalization of TH and PR. After E treatment, hypothalamic PR-positive cells increased in both intensity and number. Neurons expressing both TH and PR were detected in the rostral hypothalamus, lateral to the third ventricle (A11-rostral) and in a discrete subventricular population (A11-subvent). The lateral population continued caudally (A11-caudal). The A11-subvent population exhibited little steroid regulation. Of the remaining A11 TH neurons, approximately 20% exhibited PR in the spayed and E-treated groups. Addition of P doubled the percentage of PR-containing TH neurons in this group. Although very few TH-positive neurons in the ventral arcuate nucleus contained PR (A12-ventral), many double labeled neurons were observed in the dorsal arcuate region (A12-dorsal). Ventral arcuate TIDA neurons were not regulated by steroids, but E plus P increased PR expression in A12-dorsal. Double labeled cells were rarely seen in the zona incerta (A13) or the emerging ventral tegmental area (A10). In summary, P probably does not act directly on ventral arcuate TIDA neurons to stimulate PRL secretion. However, the frequency of PR-positive dopamine neurons in the A11-rostral, A11-caudal, and A12-dorsal groups increased with E and P treatment. Therefore, the contribution of the PR-positive periventricular dopamine neurons to progestin-stimulated PRL secretion may be important.

Animals↗

PubMed1992

Subcellular distribution of the Rap1A protein in human neutrophils: colocalization and cotranslocation with cytochrome b559.

Rap1A, a low molecular weight guanosine triphosphate-binding protein (LMWG), has been shown previously by us to be associated with purified cytochrome b from stimulated human neutrophils. In the present studies, we show that Rap1A is also associated with affinity-purified cytochrome b from unstimulated neutrophils and use specific anti-Rap1 peptide antibodies to biochemically and immunocytochemically determine the subcellular distribution of Rap1A in resting and activated human neutrophils. Analysis of the subcellular fractionation of unstimulated cells by Western blotting of isopycnic sucrose density gradient fractions with anti-Rap1 peptide antibodies indicated that Rap1A colocalized with cytochrome b in the plasma membrane as well as in the specific granule membranes and that it was translocated, along with cytochrome b, to the plasma membrane when the cells were stimulated with phorbol myristate acetate (PMA). No evidence for a cytosolic localization of Rap1A was found in our studies; however, if the cells were disrupted by sonication, rather than N2 cavitation, a fraction of the Rap1A was released from the membrane. Electron microscopy of thin sections of cryofixed, molecular-distillation dried neutrophils labeled with anti-Rap1 antibody alone or double-labeled with anti-Rap1 and anti-cytochrome b peptide antibodies confirmed our biochemical localization, and quantitation showed that more than half of the specific granule-associated Rap1A was translocated to the plasma membrane in PMA-stimulated cells. Ultrastructural analysis of neutrophils phagocytosing Staphylococcus aureus also demonstrated the translocation of Rap1A with cytochrome b. Approximately 70% of the total Rap1A labeling was associated with the phagolysosomal membrane, the site of assembly of the superoxide-generating system. The colocalization and cotranslocation of Rap1A with cytochrome b in resting and activated neutrophils is consistent with a functional association of these two molecules in the intact cell and provides further evidence for a role of this LMWG in the structure or function of the neutrophil superoxide-generating system.

Biological Transport↗

PubMed1992

Colocalization of a large heterodimeric proteoglycan with basement membrane proteins in cultured cells.

A novel large heterodimeric dermatan sulfate proteoglycan with core proteins of 460 and 300 kDa, respectively, had been described as a secretory product of human fetal skin fibroblasts (Breuer et al., J. Biol. Chem. 266, 13224-13232 (1991)). Pulse-chase experiments showed a preferential association of the proteoglycan with the cell membrane. Immunogold labeling indicated its localization in fibrils on the cell surface as well as in fibrillar extensions from the cell body. Immunofluorescence studies yielded a fibrillar and punctate staining pattern which was also seen in cultured human and porcine endothelial cells. Dot-like structures were observed in transformed human keratinocytes. Various immunocytochemical double-labeling experiments indicated a remarkable colocalization of the proteoglycan with fibronectin, laminin, perlecan, and type IV collagen whereas only occasionally a colocalization with chondroitin-6-sulfate was found. No evidence for an enrichment of the proteoglycan in vinculin-containing structures was obtained. These results suggest that the proteoglycan is a widely distributed macromolecule which can associate with basement membrane components. Preliminary findings in rat cornea supported this conclusion.

Basement Membrane↗

PubMed1991

Substance P- and enkephalin-like immunoreactivities are colocalized in certain neurons of the substantia gelatinosa of the rat spinal cord: an ultrastructural double-labeling study.

The finding that certain cells of the substantia gelatinosa of the rat spinal cord contain both substance P (SP)- and enkephalin (ENK)-like immunoreactive material offers new insights into the mechanisms of action of these peptides in the processing of nociceptive sensory information. The simultaneous detection of these immunoreactivities was obtained in the superficial dorsal horn of the rat spinal cord at the ultrastructural level using monoclonal antibodies. An internally radiolabeled monoclonal antibody (against SP or ENK) was used to recognize one antigenic site, while the other antigenic site was identified by either a bispecific monoclonal antibody (for SP) or a monoclonal antibody (for ENK). The bispecific anti-SP antibody recognized HRP, whereas a secondary bispecific antibody recognized both the IgG of the anti-ENK monoclonal antibody and HRP. In laminae I-III, SP-like immunoreactivity (SP-LI) and ENK-like immunoreactivity (ENK-LI) were colocalized in a significant number of axonal varicosities, which contained round or pleomorphic synaptic vesicles. Such double-labeled varicosities, however, were not found to be components of synaptic glomeruli. Most of the immunostained boutons of lamina I were SP-like immunoreactive only. In rats pretreated with colchicine, SP-LI and ENK-LI were colocalized in small perikarya of lamina II and in some lamina I cells. These findings indicate that SP and ENK occur in a significant population of interneurons of the superficial dorsal horn. It is suggested that some of these neurons may correspond to stalked cells and release one or the other substance depending on physiological conditions.

Animals↗

PubMed1991

Immunohistochemical colocalization of amyloid precursor protein with cerebrovascular amyloid of Alzheimer's disease.

Molecular cloning and cDNA sequencing have indicated that the fibril-forming, amyloidogenic beta/A4 peptide of cerebrovasculature and plaque core in AD is encoded as part of a larger precursor, amyloid precursor protein (APP). A panel of antibodies directed against synthetic peptides, which correspond to distinct domains of this putative APP molecule (i.e., amino acid residues 45-62, 587-596, 597-606, 597-638 [beta/A4 peptide], 638-658 and 653-661), were used to probe immunohistochemically serial sections of formalin-fixed, paraffin-embedded Alzheimer's disease (AD) brains for the presence of APP and/or its derivatives. Histochemical staining of adjacent sections with Bielschowsky's silver impregnation and with Congo red or thioflavin S-staining techniques was also done to identify the structures with amyloid deposition. All these antibodies exhibited intense immunoreactivity with amyloidotic cerebral vessels, including meningeal and parenchymal. This observation indicates that the amyloidotic vasculature of AD brain contains, in addition to the fibril-forming beta/A4 protein, nonamyloidogenic APP and/or its derivatives. More importantly, this APP immunoreactivity colocalized with angiopathic amyloid, which is characterized by phenol-resistant, birefringent congophilia. Parallel analyses with a dual SABC/silver impregnation procedure further confirmed that APP and/or its derivatives, including the amyloidogenic beta/A4, colocalized with argentophilic amyloid in the cerebrovasculature of AD.

Alzheimer Disease↗

PubMed1991

Interaction of colocalized neuropeptides: functional significance in the circadian timing system.

The suprachiasmatic nucleus (SCN), which appears to act as a circadian clock, contains a subpopulation of local circuit neurons in which vasoactive intestinal peptide (VIP), peptide histidine isoleucine (PHI), and gastrin releasing peptide (GRP) are colocalized. To determine whether VIP, PHI, and GRP interact within the SCN to produce a signal important for circadian control, the behavioral and cellular effects of coadministration of these neuropeptides were investigated. Coadministration of VIP, PHI, and GRP within the SCN mimicked the phase-delaying effects of light on circadian control following in vivo microinjection and activated SCN single units recorded in vitro. These behavioral and cellular effects of coadministration of VIP, PHI, and GRP were significantly greater than administration of VIP, PHI, or GRP alone or coadministration of any 2 of these peptides. These data illustrate a new mechanism whereby multiple, colocalized neuropeptides interact in a functionally significant manner, and indicate that the interaction of VIP, PHI, and GRP may be involved in the regulation of circadian rhythms by the SCN.

Animals↗

PubMed1991

Identification of tubulin-binding proteins of the chicken erythrocyte plasma membrane skeleton which colocalize with the microtubular marginal band.

The plasma membrane of nucleated erythrocytes contains a microtubular marginal band which appears to be associated with the plasma membrane skeleton. In this report, we identify two families of cytoskeletal proteins which may be involved in such an association. These proteins, of molecular mass 78 kDa and 48 kDa on SDS-PAGE, are shown to bind tubulin based on a 125I-labeled tubulin binding assay. Solubilization of isolated chicken erythrocyte plasma membranes in Triton X-100 shows that these proteins centrifuge with the pellet, indicating that they are bound to the membrane skeleton. Finally, immunofluorescence studies using antisera raised against the 78 kDa and 48 kDa proteins show that they colocalize with the marginal band in intact cells. Colocalization of cytoskeletal tubulin-binding proteins with the marginal band favors a hypothesis suggesting that the 78 kDa and 48 kDa proteins are involved in the association of the two molecular superstructures.

Animals↗

PubMed1990

Immunoreactive A4 and gamma-trace peptide colocalization in amyloidotic arteriolar lesions in brains of patients with Alzheimer's disease.

Cerebral amyloid angiopathy (CAA) defines a biochemically heterogeneous entity that manifests as effacement of cerebral microvessel walls by a fibrillar material with characteristic tinctorial properties. In biochemical terms, the amyloid that infiltrates blood vessels in CAA is composed of the A4 or beta peptide of Alzheimer's disease (AD), a molecule related to gamma trace or cystatin C (seen in patients with hereditary cerebral hemorrhage with amyloidosis in Iceland, HCHWA-I), or the PrP characteristic of spongiform encephalopathy and scrapie. Using antibodies to synthetic peptides representing portions of the 4.2-kd Alzheimer A4 peptide and the gamma-trace peptide, we immunostained sections of brain from patients with AD, senile dementia of Alzheimer's type, and CAA with associated leukoencephalopathy. Immunohistochemical studies demonstrated colocalization of the A4 and gamma-trace peptides within arteriolar walls, but only rarely in A4 amyloidotic capillaries or senile plaque cores of amyloid. When gamma-tracelike reactivity was noted in capillary walls, it was sometimes noted within the cytoplasm of pericytes. Immunostaining was always more intense when the anti-A4 antibody was used as the primary antibody. Gamma-trace immunostaining was more prominent on the adventitial component of arteriolar walls, whereas A4 staining was usually seen more diffusely throughout the blood vessel wall, especially in the media. Rarely individual pericytelike cells showed prominent gamma-trace immunoreactivity. These findings suggest that A4 and gamma-tracelike molecules may colocalize within arteriolar walls within the brains of patients with AD, and highlight the fact that CAA identified with AD and HCHWA-I are not as biochemically distinct as was assumed previously. Furthermore these findings suggest that other peptidases or protease inhibitors may be found within amyloidotic microvessel walls and may contribute to senile brain change and CAA-related strokes, including hemorrhage and encephalomalacia.

Aged↗

PubMed1989

Dopamine and neurotensin storage in colocalized and noncolocalized neuronal populations.

The effects of reserpine on dopamine (DA) and neurotensin (NT) levels were studied in four different brain regions of the rat. Reserpine (0.5-5.0 mg/kg i.p., 6, 18, 48 and 72 hr) produced a dose- and time-dependent decrease in both DA and NT levels in the prefrontal cortex, a brain region innervated by a mixed DA/NT projection. The effect of reserpine was not mimicked by alpha-methylparatyrosine (200 mg/kg i.p.) pretreatment. Furthermore, the reserpine-induced decline in prefrontal cortex DA and NT levels occurred after gamma-butyrolactone (GBL)-induced inhibition of impulse flow (750 mg/kg i.p.). In contrast, in the nucleus accumbens and striatum, regions which contain colocalized (nucleus accumbens) and intrinsic (striatum and nucleus accumbens) neurotensin perikarya, reserpine produced declines in DA and increases in NT levels. alpha-Methylparatyrosine decreased striatal and nucleus accumbens DA levels without altering NT levels in these structures. GBL produced an increase in DA levels in the nucleus accumbens and striatum while decreasing nucleus accumbens and striatal NT levels. Reserpine attenuated the decline in nucleus accumbens and striatal NT levels produced by GBL. In the periaqueductal grey, a brain region densely innervated by NT which has a small population of DA perikarya, reserpine had no effect on NT levels. Because there is no known colocalization of DA and NT in the striatum, the increases in striatal NT levels after depletion of DA may indicate that striatal DA afferents control the release and/or synthesis of NT within NT cells in the striatum, thus leading to alterations in striatal tissue levels.(ABSTRACT TRUNCATED AT 250 WORDS)

4-Butyrolactone↗

PubMed1988

Calmodulin colocalization with cold-stable and nocodazole-stable microtubules in living PtK1 cells.

To investigate the association of calmodulin (CaM) with microtubules (MTs) in the mitotic apparatus (MA), the distributions of both CaM and tubulin were examined in mitotic PtK1 cells in which MT subclasses had been selectively removed or altered by treatment with cold or with the MT inhibitor, nocodazole. A fluorescent CaM conjugate with tetramethylrhodamine isothiocyanate (CaM-TRITC) was microinjected into living cells, and the CaM distribution in the living cell was compared to the distribution of MTs indicated by tubulin immunofluorescence. In cells which had been treated for 2 h at 0 to 4 degrees C or with a low (0.03 micrograms/ml) dose of nocodazole, the only MTs remaining appeared to be kinetochore MTs (kMTs). The distribution of microinjected CaM-TRITC in these cells was indistinguishable from that found in untreated cells and appeared to be colocalized with the kMTs. In cells which were treated with a high (3.0 micrograms/ml) dose of nocodazole, only short MTs remained. When CaM-TRITC was injected into these cells, it formed a somewhat punctate distribution near the chromosomes and, after tubulin immunofluorescence processing, colocalized with what appeared to be remnants of kMTs. We believe that these observations support the hypothesis that CaM exists in the MA in a structural association with kMTs.

Animals↗

PubMed1988

Colocalization of taurine- and cysteine sulfinic acid decarboxylase-like immunoreactivity in the cerebellum of the rat with monoclonal antibodies against taurine.

Two monoclonal antibodies against fixative-modified taurine, Tau1 and Tau2, were produced, characterized, and used in the present study to analyze the distribution of taurine in the cerebellum of the rat. In addition, immunohistochemical colocalization experiments were performed to determine whether cerebellar neurons contain both taurine and its synthesizing enzyme, cysteine sulfinic acid decarboxylase (CSADC). In ELISAs, both Tau1 and Tau2 displayed high affinities for taurine conjugated to various carrier proteins and possessed some cross-reactivity for other amino acids which are present in lower concentrations in the brain than taurine. Tau2 was found to recognize only taurine and hypotaurine when paraformaldehyde was used to fix the amino acids to carrier proteins. With the use of glutaraldehyde fixation, Tau1 cross-reacted with conjugates of beta-alanine and hypotaurine and Tau2 cross-reacted strongly with conjugates of cysteic acid and hypotaurine and weakly with cysteine sulfinic acid. Despite different cross-reactivities, Tau1 and Tau2 exhibited almost identical patterns of neuronal staining in bands of Purkinje cells in the cerebellum. Staining of Purkinje cell dendrites was more prominent than staining of the soma. Light immunoreactivity was present in Golgi, stellate, and basket cells. A scattered population of granule cells displayed taurine-like immunoreactivity at the electron microscopic level. Immunostaining was identified in some terminals in the Purkinje cell layer and in a limited number of mossy fibers. Tau2-like immunoreactivity was colocalized with CSADC-like immunoreactivity in the cerebellar neurons described above. These immunoreactive cells may represent a subpopulation of neurons that contain a higher concentration of taurine than neighboring cells due to their ability to synthesize taurine. The intense immunoreactive staining of Purkinje cell dendrites provides support for the hypothesis that calcium-dependent release of taurine in the cerebellum may originate primarily from dendritic rather than synaptic processes and suggests a neuromodulator role for taurine in the cerebellum.

Animals↗

PubMed1992

Colocalization of thrombospondin and syndecan during murine development.

Thrombospondin is an adhesive glycoprotein that is thought to play a role in tissue genesis and repair. We have used a monoclonal anti-thrombospondin antibody, designated 5G11, to localize thrombospondin in paraformaldehyde fixed, paraffin-embedded sections of developing mouse embryos. Thrombospondin expression is observed in uterine smooth muscle, endometrial glands, the decidua, and trophoblastic giant cells during the initial phase of post-implantation development in the embryo. Cardiac myocytes and neuroepithelial cells show positive staining for thrombospondin at day 8.5 of gestation, and this expression continues throughout the development of the myocardium and central nervous system. Strong staining for thrombospondin is seen in developing bone and in the liver. Thrombospondin is also observed in developing smooth muscle and skeletal muscle, as well as in a variety of epithelia, including the epidermis, small intestinal epithelium, lens epithelium, renal tubular epithelium, and the epithelium of the developing tooth. Comparison of thrombospondin staining with that of two known cell surface receptors for thrombospondin, syndecan and the vitronectin receptor, reveals remarkable colocalization of thrombospondin and syndecan in all tissues, but almost no coexpression with the vitronectin receptor. Coexpression of thrombospondin and syndecan may play an important role in cell-cell or cell-matrix interactions during development.

Animals↗

PubMed1990

Immunohistochemical study of cerebral amyloid angiopathy. III. Widespread Alzheimer A4 peptide in cerebral microvessel walls colocalizes with gamma trace in patients with leukoencephalopathy.

Brain tissue from 11 patients with cerebral amyloid angiopathy, changes of Alzheimer's disease, and variable degrees of subcortical leukoencephalopathy was examined by immunohistochemical methods, using primary antibodies to peptide segments representing portions of the Alzheimer A4 (beta-) peptide or gamma-trace peptide (seen most commonly in Icelandic patients with cerebral hemorrhage (hereditary cerebral hemorrhage with amyloidosis [HCHWA-I]). Variable A4 immunostaining was seen within cortical (and rarely white matter) parenchyma in the form of senile plaques (with or without central cores), and within capillary and arteriolar walls. Within individual patients, A4 deposits were often primarily parenchymal or vascular, and when they were vascular they tended to be more prominent in arteriolar than in capillary wall segments. Perivascular A4 deposits were often detected around strongly immunoreactive microvessels. Gamma-trace immunoreactivity was noted in many A4-positive microvessel walls, but staining was always less intense than with the anti-A4 antibody. We conclude that patients with severe cerebral amyloid angiopathy may show wide variation in the severity and topography of A4 deposits within brain parenchyma. A4 may colocalize with gamma-trace peptide, suggesting that A4 and gamma-trace forms of cerebral amyloid angiopathy may not be as biochemically distinctive as has been suggested. Other proteases or protease inhibitors may contribute to the pathogenesis of cerebral amyloid angiopathy or cerebral amyloid angiopathy-related stroke syndromes.

Amyloid↗

PubMed1985

The renin-angiotensin system in the rat anterior pituitary: colocalization of renin and angiotensin II in gonadotrophs.

Discovery of components of the renin-angiotensin system (RAS) in the adenohypophysis of several species has prompted speculation concerning the location and possible function of a pituitary RAS. Although both renin and angiotensin II have been localized within the rat adenohypophysis, their colocalization has not been previously demonstrated within the same cells. In the present study, immunohistochemical staining by the avidin-biotin-peroxidase complex technique was used to demonstrate the coexistence of renin and angiotensin II in adenohypophyseal cells identified morphologically and immunocytochemically as gonadotrophs. These results support the existence of an adenohypophyseal RAS, at least part of which is under intracellular control. The influence of this system on control of fluid balance, blood pressure, and the secretion of other hypophyseal hormones is discussed.

Angiotensin II↗