Nerve growth factor biosynthesis: isolation and characterization of a guinea pig prostate kallikrein

Structure and biosynthesis of nerve growth factor

Most of our knowledge about NGF comes from extensive study of the mouse submaxillary gland protein. NGF from this source is isolated as a high molecular weight complex consisting of beta-NGF and two subunits, alpha and gamma, belonging to the kallikrein family of serine proteases. There are few other tissues where NGF is found in sufficient quantities for protein purification and study, although new molecular biological techniques have accelerated the study of NGFs from a variety of species and tissues. Mouse submaxillary gland NGF is synthesized as a large precursor that is cleaved at both N- and C-terminals to produce mature NGF. This biologically active molecule can be further cleaved by submaxillary gland proteases. The roles of the alpha and gamma subunits in the processing of the beta-NGF precursor, the modulation of the biological activity of beta-NGF, and the protection of mature beta-NGF from degradation have been well studied in the mouse. However, the apparent lack of alpha and gamma subunits in most other tissues and species and the existence of a large family of murine kallikreins, many of which are expressed in the submaxillary gland, challenge the relevance of murine high molecular weight NGF as a proper model for NGF biosynthesis and regulation. It is important therefore to identify and characterize other NGF complexes and to study their subunit interactions, biosynthesis, processing, and regulation. This review points out a number of other species and tissues in which the study of NGF has just begun. At this time, there exist many more questions than answers regarding the presence and the functions of NGF processing and regulatory proteins. By studying NGF in other species and tissues and comparing the processing and regulation of NGF from several sources, we will discover the unifying concepts governing the expression of NGF biological activity.

Molecular cloning of a cDNA encoding the nerve growth factor precursor from Mastomys natalensis

Mastomys natalensis is an African rat that has high levels of nerve growth factor (NGF) in its submaxillary glands. Like in the mouse, Mastomys NGF is found as a high-molecular-weight complex. However, the Mastomys complex differs from the mouse complex, in that the gamma-subunit is either missing or is less tightly bound in the Mastomys NGF complex. In the mouse, the gamma-subunit has been implicated in the processing of the beta-NGF precursor. The possible lack of gamma-subunits in the Mastomys NGF high-molecular-weight complex suggested that the Mastomys beta-NGF precursor might differ from the mouse beta-NGF precursor in some of its processing sites. In particular, Mastomys beta-NGF might lack the C-terminal dipeptide cleavage site implicated in beta-gamma subunit interactions in mouse NGF. In order to test this hypothesis, we isolated and sequenced a cDNA clone for Mastomys beta-NGF. We report here the cloning and sequencing of a cDNA coding for beta-NGF from Mastomys natalensis. The cDNA library was prepared from Mastomys submaxillary gland mRNA and the beta-NGF clone was isolated using a mouse cDNA as a probe. The nucleotide sequence of Mastomys beta-NGF is 95% homologous to that of mouse beta-NGF. In particular, the Mastomys beta-NGF precursor contains the same three C-terminal residues as the mouse, suggesting that the Mastomys beta-NGF precursor could interact with a gamma-like subunit.(ABSTRACT TRUNCATED AT 250 WORDS)

Identification and expression of kallikrein gene family in rat submandibular and prostate glands using monoclonal antibodies as specific probes

Panels of monoclonal antibodies to three vasoactive peptide-producing enzymes: tissue kallikrein, tonin and arginine esterase A were developed, characterized and used as probes for identification of tissue-specific expression. In addition, immunoblot analyses were performed, using monospecific monoclonal antibodies which did not show cross-reactivity to related-purified enzymes in enzyme-linked immunosorbant assay (ELISA), and radioimmunoassay. We obtained the following results. In rat submandibular gland extract, the expression of 38 kDa kallikrein, 32 kDa tonin, and 18 kDa heavy chain of esterase A was identified by monoclonal antibodies to kallikrein (V4D11), tonin (1F11), and esterase A (5A10, 6C11, and 4B12), respectively. In the prostate gland, a 32 kDa kallikrein-like protein was identified by monoclonal antibodies to esterase A (5A10, 6C11 and 4B12) and by antibodies recognizing both tonin and esterase A (5A5), but not by antibody to kallikrein (V4D11) or to tonin (1F11, 1G6) in Western blot analysis. The esterase A-like enzyme in the prostate gland was found within the cytoplasm of ductal epithelial cells by using monoclonal anti-esterase A antibody (5A10) but not by employing anti-tonin antibody (1F11). These results indicate that tissue kallikrein, tonin, and esterase A are all expressed in the submandibular gland, while only esterase A or an esterase A-like enzyme is expressed in the prostate gland. The specific monoclonal antibodies can be used as probes for the identification and expression of the kallikrein gene-family enzymes.

De novo synthesis of NGF subunits in S-180 mouse sarcoma cell line

It is an accepted hypothesis that the nerve growth factor protein (NGF) plays an important role in the development of vertebrate sympathetic and sensory ganglia and has effects on some central neurons. The best known NGF species is that isolated from mouse submaxillary gland, MSG-NGF. MSG-NGF can be isolated as a subunit containing protein, 7S-NGF, made up of three dissimilar subunits called alpha-, beta-, and gamma-NGF. Beta-NGF is the biologically active subunit and its synthesis in vivo and in vitro has been demonstrated. Less is known about the synthesis of the alpha- and gamma-NGF or the assembly of the subunits into the 7S complex. In order to develop a clonal model system for the study of NGF synthesis, processing and secretion, affinity chromatography techniques were applied to cell extracts of S180 mouse sarcoma, a cell line known to synthesize NGF. After incubating S180 cells in 35S-Methionine, cell extracts were exposed to antibody directed against alpha-NGF, gamma-NGF or beta-NGF covalently bound to Sepharose beads in order to elute and characterize the desired NGF subunits. Parallel experiments using immunoabsorbed [35S]Methionine-beta-NGF were carried out in the presence or absence of excess NGF, in order to demonstrate the specificity of this procedure. Affinity chromatography with a substrate analogue to arginine ester bound to Sepharose beads was also used to isolate de novo synthesized gamma-NGF.(ABSTRACT TRUNCATED AT 250 WORDS)

Role of glandular kallikreins as growth factor processing enzymes: structural and evolutionary considerations

Hormones and growth factors are generally released from larger precursors by limited proteolysis. The causative agents remain poorly defined with respect to location and properties. One subset of proteases, the glandular kallikreins, have been implicated in a few cases, in part because of their specific association with mature forms of some hormones. However, limited distribution and low copy number in some species cast doubt on this hypothesis, and they may well play other physiological functions that remain to be elucidated.

Nerve growth factor immunoreactivity in mouse kidney: an immunoelectron microscopic study

We have recently reported the immunolocalization of nerve growth factor (NGF) in mouse kidney by light microscopy. In the present study, we have investigated the ultrastructural localization of NGF by the preembedding immunoperoxidase method for electron microscopy. NGF immunoreactivity was present in the connecting tubule cells of the distal nephron. These cells showed immunostaining associated with the Golgi complex, vesicles, rough endoplasmic reticulum (RER), and polyribosomes. The intercalated cells, in contrast, lacked immunoreactivity.