Chromosomal locations of the human and mouse genes for precursors of epidermal growth factor and the beta subunit of nerve growth factor

[Precursors and propeptides of neurotrophic factors as the modulators of biological activity of its mature forms]

Here, we review the problems of neurotrophic factors' folding, the role of its precursors (proneurotrophins) and the contribution of elements deleted during its maturation (propeptides) in biological functioning of these growth factors.

The nerve growth factor and its receptors in airway inflammatory diseases

The nerve growth factor (NGF) belongs to the neurotrophin family and induces its effects through activation of 2 distinct receptor types: the tropomyosin-related kinase A (TrkA) receptor, carrying an intrinsic tyrosine kinase activity in its intracellular domain, and the receptor p75 for neurotrophins (p75NTR), belonging to the death receptor family. Through activation of its TrkA receptor, NGF activates signalling pathways, including phospholipase Cgamma (PLCgamma), phosphatidyl-inositol 3-kinase (PI3K), the small G protein Ras, and mitogen-activated protein kinases (MAPK). Through its p75NTR receptor, NGF activates proapoptotic signalling pathways including the MAPK c-Jun N-terminal kinase (JNK), ceramides, and the small G protein Rac, but also activates pathways promoting cell survival through the transcription factor nuclear factor-kappaB (NF-kappaB). NGF was first described by Rita Levi-Montalcini and collaborators as an important factor involved in nerve differentiation and survival. Another role for NGF has since been established in inflammation, in particular of the airways, with increased NGF levels in chronic inflammatory diseases. In this review, we will first describe NGF structure and synthesis and NGF receptors and their signalling pathways. We will then provide information about NGF in the airways, describing its expression and regulation, as well as pointing out its potential role in inflammation, hyperresponsiveness, and remodelling process observed in airway inflammatory diseases, in particular in asthma.

Lipopolysaccharide-induced elevation and secretion of interleukin-1beta in the submandibular gland of male mice

The intraperitoneal injection of lipopolysaccharide (LPS) (400 microg/kg body weight) induced the expression of mRNAs of inflammatory cytokines such as interleukin (IL)-1beta, IL-6 and tumour necrosis factor (TNF)-alpha in the submandibular gland (SMG) of C3H/HeN mice but not that of C3H/HeJ mice, a mutant strain for Toll-like receptor-4 (TLR-4(-) mutant). The mRNA levels of these cytokines in the SMG of the wild-type mice increased as early as 3 hr after injection, peaked at 3-6 hr, and had decreased again by 24 hr. In this study, we particularly focused on IL-1beta, and induction by this endotoxin was investigated in detail. Denervation of the superior cervical trunk and chorda tympani nerve did not diminish the LPS-induced elevation of IL-1beta mRNA in the SMG, indicating the irrelevance of the central nervous system in this induction. TLR-4 mRNA and protein were shown to be strongly expressed in the SMG, suggesting the direct action of LPS on this gland. IL-1beta proteins were localized in the secretory granules of granular convoluted tubular (GCT) cells, and their molecular weights in the gland were 17.5 and 20 kDa. IL-1beta of the same size appeared in the saliva 6 hr after LPS injection in C3H/HeN but not in C3H/HeJ mice. The present study thus suggests that IL-1beta, an inflammation cytokine, is induced and secreted into the saliva in response to endotoxin injected intraperitoneally.

The possible role of neurotrophins in the pathogenesis and therapy of schizophrenia

The pathogenesis of schizophrenia may be ascribed to early maldevelopment of brain tissue. Neurotrophins are a group of dimeric proteins that affect the development of the nervous system in all vertebrates' species. Since neurotrophins, as well as other growth factors, play a crucial role in neurodevelopment, they are plausible candidates of taking part in the pathophysiology of schizophrenia. In line with this hypothesis, accumulating preclinical and clinical data indicate that dysfunctions of nerve growth factor (NGF), brain derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) may contribute to impaired brain development, neuroplasticity and synaptic "dysconnectivity" leading to the schizophrenic syndrome, or at least some of its presentations. This article reviews the functions of neurotrophins in the complex process of normal brain development, and their possible relevance to the neuropathology and neuropharmacology of schizophrenia. Further research in this area may bring about novel pharmacological therapeutic strategies to this chronic debilitating disorder.

Growth factors in glioma angiogenesis: FGFs, PDGF, EGF, and TGFs

It has become well accepted that solid tumors must create a vascular system for nutrient delivery and waste removal in order to grow appreciably. This process, angiogenesis, is critical to the progression of gliomas, with vascular changes accompanying the advancement of these tumors. The cascade of events in this process of blood vessel formation involves a complex interplay between tumor cells, endothelial cells, and their surrounding basement membranes in which enzymatic degradation of surrounding ground substance and subsequent endothelial cell migration, proliferation, and tube formation occurs. It is likely that a host of growth factors is responsible for mediating these key events. To date, a role for Vascular Endothelial Growth Factor (VEGF) in glioma angiogenesis has been convincingly demonstrated. This review explores the contribution of other growth factors--Fibroblast Growth Factors (FGFs), Platelet-Derived Growth Factor (PDGF), Epidermal Growth Factor (EGF), and Transforming Growth Factors (TGFs)--to glioma angiogenesis. These growth factors may influence glioma angiogenesis by directly stimulating endothelial cell proliferation, by mediating the expression of key proteases on endothelial cells necessary for angiogenesis, or by regulating the expression of VEGF and of each other.

Molecular cloning, characterization, and genetic mapping of the cDNA coding for a novel secretory protein of mouse. Demonstration of alternative splicing in skin and cartilage

A novel 85-kDa protein secreted by the mouse stromal osteogenic cell line MN7 was identified using two-dimensional polyacrylamide gel electrophoresis (Mathieu, E., Meheus, L., Raymackers, J., and Merregaert, J. (1994) J. Bone Miner. Res. 9, 903-913). Degenerate primers were used to isolate the cDNA coding for this protein. The full-length cDNA clone is 1.9 kilobases (kb) and codes for a protein of 559 amino acid residues. The DNA and deduced amino acid sequences have no counterparts in public data bases, but a structural similarity involving typical cysteine doublets can be observed to serum albumin family proteins and to Endo16 (a calcium-binding protein of sea urchin). Northern blot analysis revealed the presence of a 1.9-kb transcript in various tissues, and a shorter transcript of 1.5 kb, derived by alternative splicing in tail, front paw and skin of embryonic mice. The gene for the p85 protein, termed Ecm1 (for extracellular matrix protein 1), is a single-copy gene, which was localized to the region on mouse chromosome 3 known to contain at least one locus associated with developmental disorders of the skin, soft coat (soc). Alternative splicing may serve as a mechanism for generating functional diversity in the Ecm1 gene.

Biphenotypic M0 acute myeloid leukemia with trisomy-4

We report here a rare case of biphenotypic M0 acute myeloid leukemia (AML) associated with trisomy 4. The literature of trisomy 4 in acute leukemia was reviewed. M2 and M4 AML are the most common FAB subtypes associated with trisomy 4. The clinical course of this entity is generally comparable with other non-trisomy 4 cases of AML. Despite the speculation made when first described, no specific environmental toxin has been found to be associated with this entity. C-kit oncogene has been mapped to chromosome 4 recently, and the role of this proto-oncogene in leukemogenesis of trisomy 4 associated leukemia should be further investigated.

Rieger syndrome revisited: experimental approaches using pharmacologic and antisense strategies to abrogate EGF and TGF-alpha functions resulting in dysmorphogenesis during embryonic mouse craniofacial morphogenesis

The major manifestations of Rieger syndrome (RS), an autosomal dominant disorder, include absent maxillary incisor teeth, malformations of the anterior chamber of the eye, and umbilical anomalies [Aarskog et al., 1983: Am J Med Genet 15:29-38; Gorlin et al., 1990: "Syndromes of the Head and Neck" 3rd ed.]. Linkage of RS to human chromosome 4q markers has been identified with tight linkage to epidermal growth factor (EGF) [Murray et al., 1992: Nat Genet 2:46-48]. Mutations associated with genes of the EGF superfamily are implicated in malformations arising from abnormal development of the first branchial arch [Ardinger et al., 1989: Am J Hum Genet 45:348-353; Sassani et al., 1993: Am J Med Genet 45:565-569]. Down-regulation of EGF during early mouse development results in ablation of tooth formation [Kronmiller et al., 1991: Dev Biol 147:485-488]. Since EGF, TGF-alpha, and EGF receptor (EGFr) transcripts are expressed in the mouse first branchial arch and derivatives, experimental strategies were employed to investigate the consequences of down-regulation of EGF translation and inhibition of EGF receptor during embryonic mandibular morphogenesis. Antisense inhibition of EGF expression produces mandibular dysmorphogenesis with decreased tooth bud size; these effects are reversed by the addition of exogenous EGF to the culture medium [Shum et al., 1993: Development 118:903-917]. Tyrphostin RG 50864, which inhibits EGF receptor kinase activity, inhibits EGF or TGF-alpha stimulation of tyrosine phosphorylation in a concentration-dependent manner and severely retards mandibular development [Shum et al., 1993: Development 118:903-917].(ABSTRACT TRUNCATED AT 250 WORDS)

EGF abrogation-induced fusilli-form dysmorphogenesis of Meckel's cartilage during embryonic mouse mandibular morphogenesis in vitro

Mutations associated with genes of the EGF superfamily are implicated in facial malformations arising from abnormal development of the first branchial arch. EGF and EGF receptor (EGFr) transcripts are expressed in the mouse embryonic first branchial arch and derivatives from E9 through E15. EGF transcripts are localized to ectomesenchymal cells associated with precartilage, cartilage, bone and tooth-forming cells. EGF and EGFr proteins co-localize to the same cells suggesting an autocrine regulation. To test whether EGF effects the timing and positional information required for Meckel's cartilage (MC) and tooth development, we cultured E10 mandibular explants in serumless, chemically defined medium with either antisense or sense EGF oligodeoxynucleotides. Antisense inhibition of EGF expression produces bilaterally symmetrical Fusilli-form dysmorphogenesis of MC and decreases tooth bud size; these effects are reversed by the addition of exogenous EGF to the culture medium. Tyrphostin RG 50864, which inhibits EGF receptor kinase activity, inhibits EGF stimulation of tyrosine phosphorylation in a concentration-dependent manner and severely retards mandibular development yet increases tooth size. These findings support the hypothesis that endogenous EGF and EGF-like proteins provide signalling to regulate the size and shape both of cartilage and tooth formation during craniofacial morphogenesis.

PAX8, a human paired box gene: isolation and expression in developing thyroid, kidney and Wilms’ tumors

Recent evidence indicates a crucial role for paired box genes in mouse and human embryogenesis. The murine Pax8 gene encodes a sequence-specific transcription factor and is expressed in the developing secretory system as well as in the developing and adult thyroid. This restricted expression pattern suggested involvement of the Pax8 gene in the morphogenesis of the above organs and prompted us to investigate the PAX8 gene in humans. In this report, we describe the isolation and characterization of PAX8 cDNAs from a human adult kidney cDNA library. An open reading frame of 450 amino acids contains the 128 amino acid paired domain at its amino-terminal end. The predicted human and mouse Pax8 proteins show 97.8% conservation and are identical in their paired domains. Two independent cDNA clones reveal differential splicing of the PAX8 transcripts resulting in the removal of a 63 amino acid serine-rich region from the carboxy end of the predicted Pax8 protein. The truncated Pax8 protein becomes more similar to the predicted murine Pax2 protein, that is also expressed during kidney development and lacks the serine rich region. RNAse protection analysis shows the presence of both PAX8 transcripts in human thyroid, kidney and five Wilms’ tumors. No truncated Pax8 transcripts could be detected in mouse kidney. In situ hybridization to sections of human embryonic and fetal kidney showed expression of PAX8 in condensed mesenchyme, comma-shaped and S-shaped bodies. In contrast, PAX2 expression was present mainly in the very early stages of differentiation, in the induced, condensing mesenchyme. This restricted expression pattern suggests a specific role for both genes during glomeruli maturation.(ABSTRACT TRUNCATED AT 250 WORDS)

Organization and chromosomal locations of Rap1a/Krev sequences in the mouse

The human RAP1A gene encodes a protein that apparently can antagonize the function of oncogenic ras genes in gene transfer experiments, but its normal function is unknown. To understand the function of this gene, we have undertaken a study of the mouse homolog, Rap1a. The complete coding sequence of a mouse Rap1a cDNA has been determined, and genomic clones representing three distinct Rap1a species were recovered. We find that Rap1a is located on distal mouse Chromosome (Chr) 3 near Nras, Ampd-1, Tshb, Ngfb, and Atp1a1. Two related sequences (Rap1a-rs1 and Rap1a-rs2) were also characterized. Rap1a-rs1, which was not localized, has a sequence very similar to the Rap1a cDNA, suggesting that it has been recently acquired by the mouse genome. Rap1a-rs2 is more distantly related to the gene sequence and is located on Chr 2 near Actc-1.

Expression of epidermal growth factor and its mRNA in pig kidney, pancreas and other tissues

The levels of epidermal growth factor (EGF) mRNA in a wide range of pig tissues were measured by a RNAase-protection assay. The highest levels were found in kidney and pancreas, with lower levels in submaxillary gland, prostate gland and seminal vesicles. Immunocytochemical staining using an antiserum raised against recombinant pig EGF localized expression of the factor to the distal convoluted tubules of the kidney and to the epithelial cells lining the pancreatic and salivary ducts. The observed expression of EGF mRNA and EGF in pig tissues is consistent with a possible role for EGF in the maintenance and repair of the epithelial lining of various ductal systems.

Chromosomal localization of Cd1d genes in the mouse

Southern blot hybridization of DNA from Chinese hamster x mouse somatic cell hybrids was used to assign the mouse Cd1d genes to chromosome 3. Analysis of the progeny of an intersubspecies backcross was used to position these genes near the gene for glucocerebrosidase, Gba.

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.

Regulation of the differentiation of PC12 pheochromocytoma cells

The PC12 clone, developed from a pheochromocytoma tumor of the rat adrenal medulla, has become a premiere model for the study of neuronal differentiation. When treated in culture with nanomolar concentrations of nerve growth factor, PC12 cells stop dividing, elaborate processes, become electrically excitable, and will make synapses with appropriate muscle cells in culture. The changes induced by nerve growth factor lead to cells that, by any number of criteria, resemble mature sympathetic neurons. These changes are accompanied by a series of biochemical alterations occurring in the membrane, the cytoplasm, and the nucleus of the cell. Some of these events are independent of changes in transcription, while others clearly involve changes in gene expression. A number of the alterations seen in the cells involve increases or decreases in the phosphorylation of key cellular proteins. The information available thus far allows the construction of a hypothesis regarding the biochemical basis of PC12 differentiation.

Genes encoding alpha and beta subunits of Na,K-ATPase are located on three different chromosomes in the mouse

We have made use of a panel of mouse-hamster somatic cell hybrids and restriction fragment length polymorphisms between two mouse species (Mus musculus and Mus spretus) to determine the chromosomal localization of genes encoding the alpha and beta subunits of the Na,K-ATPase (Na+,K+-activated ATP phosphohydrolase, EC 3.6.1.3). DNA probes for three distinct isoforms of the Na,K-ATPase alpha subunit mapped to three different mouse chromosomes: the alpha 1 gene (Atpa-1) cosegregated with the Egf gene on chromosome 3; alpha 2 (Atpa-2) with the cytochrome P-450PB gene family/coumarin hydroxylase locus on chromosome 7; alpha 3 (Atpa-3) with the alpha-spectrin gene on chromosome 1. The Na,K-ATPase beta-subunit gene (Atpb) mapped to the same region of chromosome 1, but it was not tightly linked to the Atpa-3 gene. These results indicate that three isoforms of the Na,K-ATPase alpha subunit are encoded by three distinct genes. The dispersion of Na,K-ATPase genes suggests that their expression is not likely to be controlled by a common cis-acting regulatory element.

Novel non-isotopic in situ hybridization technique detects small (1 Kb) unique sequences in routinely G-banded human chromosomes: fine mapping of N-myc and beta-NGF genes

A novel in situ hybridization technique is described. This non-radioactive technique combines, for the first time, the high spacial resolution and rapid signal development of the non-isotopic approach with the previously unrivalled sensitivity of autoradiography. The procedure, which employs biotin labelled DNA probes and a streptavidin-alkaline phosphatase based detection system, is compatible with pre G-banding and can be performed on archival material. Unique sequences as small as 1 Kb are detectable. Using this technique, we have mapped the N-myc oncogene and the gene for beta-Nerve Growth Factor to 2p24 and 1p13 respectively.

Human chromosomes 6 and 21 are required for sensitivity to human interferon gamma

The human interferon gamma receptor has previously been assigned to chromosome 6. Chromosome 6 also encodes HLA, the human class I major histocompatibility antigens. However, the presence of chromosome 6 in hamster-human hybrids is by itself insufficient to confer sensitivity to human immune interferon as measured by the induction of human HLA. Human chromosome 21 was found to be the second chromosome essential for HLA inducibility. Similar results were found with mouse-human somatic cell hybrids. Thus, at least two steps are involved in the action of human interferon gamma: the binding of interferon gamma to its receptor coded by chromosome 6 and the linkage of this binding event through a factor coded by chromosome 21 to trigger biological action. Both of these steps are species-specific.

Molecular genetics of human chromosome 4

The recent discovery that the gene causing Huntington's disease (HD) resides on chromosome 4 has generated increased interest in this autosome. Chromosome 4 contains two of the more informative conventional genetic markers, GC and MNS, but most loci have been assigned to it by recombinant DNA techniques. There are currently more anonymous DNA fragments detecting restriction fragment length polymorphisms (RFLPs) on chromosome 4 than on any other autosome. In addition, most of the cloned genes from this chromosome detect useful RFLPs. A genetic linkage map including both conventional and DNA markers should soon span the entire chromosome and will undoubtedly lead to the localisation of other inherited disorders.

Mapping thyrotropin beta subunit gene in man and mouse

Thyrotropin (TSH) is composed of two subunits: alpha and beta. Previously, we have mapped the TSH alpha gene to human chromosome 6 and mouse chromosome 4. In this study we have located the human TSH beta gene on chromosome 1 and the mouse TSH beta gene to chromosome 3. These data suggest that the TSH beta gene lies in a conserved linkage group with the genes for amylase 1 and 2, nerve growth factor, and the protooncogene Nras.