Umbilicated lesions in leprosy.
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Diagnosis, Differential↗
Biomedical subjects
A Zaheer
Publications and source records attributed to A Zaheer.
Ciliary neurotrophic factor (CNTF) enhances the effects of nerve growth factor on PC12 cells.
The rat pheochromocytoma cell line PC12 responds readily to nerve growth factor (NGF) but poorly to ciliary neurotrophic factor (CNTF). However, in a selected line derived from PC12 that normally responded weakly to NGF, CNTF potentiated the effect of NGF with respect to inhibition of proliferation, neurite outgrowth, and choline acetyltransferase (ChAT) induction. ChAT activity was assayed enzymatically, and an increase in the mRNA of ChAT was also detected by means of reverse transcription-polymerase chain reaction (RT-PCR). The PCR product was verified by sequencing and by Southern hybridization using a specific oligonucleotide probe. The presence of CNTF receptor in PC12 cells was confirmed by RT-PCR for its mRNA. The results indicate that PC12 responds to CNTF mainly when used in combination with NGF, and suggest an interaction between the two growth factors.
Adrenal Gland Neoplasms↗
Expression of glia maturation factor beta mRNA and protein in rat organs and cells.
Rat glia maturation factor beta (GMF-beta) cDNA was obtained by reverse transcription of rat brain mRNA followed by polymerase chain reaction amplification, using primers from the human sequence. The deduced amino acid sequence of rat GMF-beta differed from the human counterpart in only three places: His27 in place of Asn, Val51 in place of Ile, and Leu93 in place of Val. The high degree of evolutionary conservation suggests that GMF-beta plays an essential role in animal cell physiology. The expression of GMF-beta mRNA in the rat was studied by the northern blot technique, using a rat cRNA probe corresponding to the entire coding region. GMF-beta mRNA was predominantly expressed in the brain and spinal cord, although trace levels were found in other organs, including testis and ovary. In the brain GMF-beta mRNA was detectable at as early as embryonic day 10, and persisted through as late as postnatal month 14, with minor variations in between. On the other hand, GMF-beta protein exhibited more obvious developmental changes, with its level increasing slowly prenatally and plateauing at 1 week after birth. GMF-beta mRNA and protein were also observed in several cultured cells. Some cells of neural origin contained higher levels of GMF-beta protein compared with cells derived from other sources. Through demonstration of mRNA and confirmation by immunoblotting, we conclude that GMF-beta is synthesized by rat organs and that GMF-beta is predominantly a brain protein.
Amino Acid Sequence↗
Polyclonal antibody localizes glia maturation factor beta-like immunoreactivity in neurons and glia.
A rabbit polyclonal antibody (91-01) was raised against recombinant human glia maturation factor beta (r-hGMF-beta). The antibody did not cross-react with a number of other growth factors on ELISA test. When compared with the monoclonal antibody G2-09 previously obtained, 91-01 immunoblotted the same protein band in rat brain extract. However, unlike G2-09 which immunostained only astrocytes and Bergmann glia, 91-01 stained neurons as well. Many but not all neurons in the central and peripheral nervous system were positive for GMF-beta. The larger cell population stained by the polyclonal antibody was most likely due to its increased sensitivity, although other explanations are possible. The presence of GMF-beta-like immunoreactivity in both neurons and glia raises the possibility of a wider range of cell-cell interaction than was previously considered.
Animals↗
Expression of glial fibrillary acidic protein in human medulloblastoma cells treated with recombinant glia maturation factor-beta.
Medulloblastoma, a common pediatric brain tumor, is a primitive neuroectodermal tumor which often displays neuronal and/or glial characteristics. We have investigated the consequences of treating cell lines derived from a human medulloblastoma with glia maturation factor-beta (GMF-beta), a protein found in mammalian brain. GMF-beta promotes growth arrest and morphological alteration of cultured glioma and neuroblastoma cells. The proliferation of medulloblastoma cells was arrested 24-48 hr after exposure to human recombinant GMF-beta. During the same period, treated cells acquired a morphology similar to that of mature astrocytes. By 72 hr, all treated cells bound an antibody against glial fibrillary acidic protein (GFAP), a distinguishing biochemical feature of mature astrocytes. Immunoreactivity was accompanied by de novo expression of GFAP mRNA. Our observations are the first demonstration of the induction of morphological and biochemical characteristics of mature astrocytes in cultured medulloblastoma-derived cells by an exogenous factor.
Cell Division↗
Glia maturation factor beta stimulates axon regeneration in transected rat sciatic nerve.
Rat sciatic nerves were bilaterally transected and repaired with an entubulation technique. The nerve interstump gap was filled with either collagen gel or collagen gel mixed with a putative neurotrophic factor (leupeptin, 4-aminopyridine, lipid angiogenic factor or glia maturation factor beta (GMF-beta]. Six weeks after nerve transection, the myelinated distal stump axons were quantified for each nerve. Only the nerves treated with GMF-beta had significantly more axons than the control side.
Animals↗
Structure and function of glia maturation factor beta.
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Amino Acid Sequence↗
Molecular cloning and expression of biologically active human glia maturation factor-beta.
Glia maturation factor-beta, a protein found in the brains of all vertebrates thus far examined, appears to play a role in the differentiation, maintenance, and regeneration of the nervous system. Using oligonucleotide probes based on the sequences of three tryptic peptides derived from bovine glia maturation factor-beta, we screened a human brainstem cDNA library in lambda gt11. A 0.7-kb clone was isolated, sequenced in its entirety, and found to encode a polypeptide of 142 amino acids which contained regions identical to the three bovine peptides. This polypeptide, human recombinant glia maturation factor-beta, has been expressed in Escherichia coli and found to possess structural characteristics and biological activity indistinguishable from those of the native bovine protein.
Amino Acid Sequence↗
Disulfide isoforms of recombinant glia maturation factor beta.
Recombinant human glia maturation factor beta (r-hGMF-beta) is a single-chain polypeptide (141 amino acid residues) containing three cysteines, at positions 7, 86 and 95. Nascent r-hGMF-beta exists in the reduced state and has no biological activity. The protein can be activated through oxidative refolding by incubation with a mixture of reduced and oxidized glutathione. Reverse-phase HPLC analysis of the refolded r-hGMF-beta shows the presence of four peaks, corresponding to the reduced form plus three newly generated intrachain disulfide-containing isoforms predicted from the number of cysteine residues. Only one isoform shows biological activity when tested for growth suppression on C6 glioma cells. We infer from the HPLC elution pattern that the active form contains the disulfide bridge Cys86-Cys95.
Animals↗
Glia maturation factor beta regulates the growth of N18 neuroblastoma cells.
Glia maturation factor beta (GMF-beta) is a 17-kDa growth regulating protein isolated from the brain. The effect of bovine GMF-beta on neurons was tested on the neuroblastoma line N18 and the pheochromocytoma line PC12. GMF-beta inhibited the proliferation of N18 cells and promoted their neurite outgrowth, with an increase in neurofilament protein, but had no effect on PC12 cells. This was in contrast to nerve growth factor (NGF) which regulated PC12 but not N18. Acidic fibroblast growth factor (FGF), on the other hand, had a weak effect on PC12 but none on N18. Antisera against GMF-beta and NGF neutralized the biological activity of the corresponding growth factors but showed no cross-neutralization. Fluorescence visualization revealed the binding of GMF-beta to N18 cells but not to PC12 cells; the opposite was true with NGF.
Adrenal Gland Neoplasms↗
Complete amino acid sequence of bovine glia maturation factor beta.
The protein glia maturation factor beta, isolated from bovine brain, has been sequenced by automated Edman degradation and tandem mass spectrometry of overlapped peptide fragments generated by cyanogen bromide cleavage and enzymatic digestion with trypsin, chymotrypsin, and endoproteinases Asp-N and Lys-C. The protein has 141 amino acid residues and possesses no potential N-glycosylation sites. It contains three cysteines (at positions 7, 86, and 95), three methionines (at positions 33, 101, and 102), and one tryptophan (at position 132). The blocked amino terminus as determined by tandem mass spectrometry is an N-acetylated serine. The carboxyl terminus is a histidine. To our knowledge, the sequence shows no significant homology with other sequenced proteins. The molecular weight calculated from the sequence information is 16,582.
Amino Acid Sequence↗
Antiproliferative function of glia maturation factor beta.
Recombinant human glia maturation factor beta (GMF-beta) reversibly inhibits the proliferation of neoplastic cells in culture by arresting the cells in the G0/G1 phase. This phenomenon is not target-cell specific, as neural and nonneural cells are equally inhibited. When tested simultaneously, GMF-beta suppresses the mitogenic effect of acidic fibroblasts growth factor (aFGF), but the two are synergistic in promoting the morphologic differentiation of cultured astrocytes. GMF-beta also counteracts the growth-stimulating effect of pituitary extract and cholera toxin on Schwann cells. The results underscore the regulatory role of GMF-beta and its intricate interaction with the mitogenic growth factors.
Animals↗
Cell-surface expression of glia maturation factor beta in astrocytes.
Glia maturation factor beta (GMF-beta) is a 17-kDa acidic protein isolated from the brain. When added to cultured cells, GMF-beta promotes the phenotypic expression of glia and neurons and inhibits the proliferation of their respective tumors. Although astrocytes produce GMF-beta and store it inside the cells, they do not secrete the protein into the cultured medium. This poses a question as to how GMF-beta mediates intercellular communication. This paper provides an answer by demonstrating the presence of GMF-beta on the surface of astrocytes, using gold-labeled antibody enhanced with silver. It appears that cell-surface GMF-beta acts on the target cells at close range when cells are in direct contact. In contrast to astrocytes, we failed to detect GMF-beta on the surface of C6 glioma cells, although these cells, like astrocytes, possess endogenous intracellular GMF-beta and are also responsive to GMF-beta added to the medium. The lack of cell-surface expression of GMF-beta in C6 cells may reflect a breakdown in intercellular communication in these malignant cells.
Animals↗
Purification and characterization of glia maturation factor beta: a growth regulator for neurons and glia.
A protein has been isolated from bovine brains by using a modification of the procedure used to purify glia maturation factor. The method consists of ammonium sulfate precipitation, chromatography with DEAE-Sephacel, Sephadex G-75, and hydroxylapatite columns, passage through a heparin-Sepharose column, and finally fractionation by reverse-phase HPLC with a C4 column. The isolated protein reacts strongly with the mouse monoclonal antibody G2-09 and has a molecular weight of approximately 17,000 and an isoelectric point of pH 4.9. The N terminus is blocked, but tryptic digestion releases 28 peptides, 8 of which have been sequenced. The total known residues add up to more than two-thirds of the entire 140-residue protein, estimated from amino acid composition, and show no sequence homology with any known protein. Reversible thermal renaturation greatly enhances its biological activity. The purified protein stimulates differentiation of normal neurons as well as glial cells. It inhibits the proliferation of the N-18 neuroblastoma line and the C6 glioma line while promoting their phenotypic expression. We designate this protein glia maturation factor beta.
Amino Acids↗
Peptidase activity of macromomycin apoprotein.
Macromomycin, an antibiotic and antitumor protein obtained from Streptomyces macromomyceticus, displayed specific aminopeptidase activity. Pure macromomycin degraded the beta-chain of insulin, a few synthetic di- and tripeptides, and a number of proteins of KB cell plasma membrane. The biological activity and the peptidase activity showed similar temperature-dependent patterns suggesting that one protein is responsible for both activities. The apoprotein contained the aminopeptidase activity while the chromophore, which displayed the antibiotic and antitumor activity, did not show any such activity.
Amino Acids↗
Proteolytic activity of largomycin.
Largomycin, an antibiotic and antitumor protein, purified from the culture broth of Streptomyces pluricolorescens, displayed specific proteolytic activity. Pure largomycin did not degrade a number of substrates commonly used for detection of aminopeptidase, endopeptidase and carboxypeptidase activity. Pure largomycin degraded angiotensin II, bradykinin, a few dipeptides and a number of proteins of KB cell plasma membranes. The biological activity and the proteolytic activity of largomycin showed similar temperature-dependent patterns, suggesting that one protein is responsible for both activities. The apoprotein of largomycin, which did not show antibiotic activity, contained the proteolytic activity.
Aminoglycosides↗
Largomycin: preparation, properties, and structure.
Largomycin has been purified to homogeneity by chromatography on hydroxylapatite whereby carbohydrate and protease impurities were removed. Largomycin is an acidic protein (pI 4.13, molecular weight 29300) which forms a dimer in phosphate buffer. An N-terminal amino acid sequence analysis from the amino-terminal residue gave, for the first 32 residues, Asp-Ile-Leu-Ile-Ala-Gly-Ala-Thr-Gly-Asn-Val-Gly-Lys-Pro-Leu-Val-Glu-Gly-Leu-Leu - Ala-Ala-Gly-Lys-Pro-Val-Arg-Ala-Leu-Thr-Arg-Asn... The sequence from the carboxyl terminus was -Ala-Ala-Leu-Phe-OH with threonine, valine, and glutamic acid being released upon prolonged digestion. The same amino acid sequences were found for largomycin prepared from either the culture broth or the mycelium of Streptomyces pluricolorescens. The similarities extended to the other physical properties, the antimicrobial activity against Staphylococcus aureus and Sarcina lutea, and the antitumor activity against KB cells. Largomycin inhibits the biosynthesis of DNA and RNA. An iodinated derivative did not bind to KB cells. The antimicrobial activity was lost following ultraviolet irradiation, protection against which was not afforded by p-aminobenzoic acid.
Amino Acid Sequence↗
(Na (+) + K (+)-stimulated ATPase of human kidney, normal and adenocarcinoma. Phosphorylation and inhibition by antitumor proteins.
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Adenocarcinoma↗