Biomedical subjects

E C Salido

Publications and source records attributed to E C Salido.

33 records · Page 2Linked to original sources

PubMed1992

Epidermal growth factor prohormone is secreted in human urine.

Examination of adult human urine by immunoblot analysis with antiserum specific to human recombinant 6-kDa epidermal growth factor (EGF) reveals the presence of an immunoreactive protein with a molecular mass of 165 kDa. This protein is consistently found in the morning (first) but not in day urine of adult males and females. Day urine contains variable proportions of four other high-molecular-weight EGFs with approximate molecular masses of 97, 66, 50, and 42 kDa. The 165-kDa EGF immunoreactive protein reacts with mouse amino-terminal EGF prohormone (proEGF) antiserum and comigrates with mouse urinary proEGF, suggesting that the protein is the human EGF prohormone. The 165-kDa human proEGF exhibits strong binding affinity to concanavalin A, indicating that it is glycosylated. Immunoblotting of urine in infants and children of various age groups demonstrates the presence of proEGF in all age groups, but its concentration is highest in children 2-4 yr of age. These findings, taken together with secretion of proEGF of similar molecular mass in mouse and rat urine, suggest that renal proEGF secretion is an evolutionarily conserved phenomenon and may have an important function or functions distal to the site of its synthesis.

Adult↗

PubMed1992

The human enamel protein gene amelogenin is expressed from both the X and the Y chromosomes.

Amelogenins, a family of extracellular matrix proteins of the dental enamel, are transiently but abundantly expressed by ameloblasts during tooth development. Amelogenins seem to regulate the formation of crystallites during the secretory stage of enamel development, while they are specifically degraded during tooth-bud maturation. In this paper we report the characterization of the AMGX and AMGY genes on the short arms of the human X and Y chromosomes which encode the amelogenins. Our studies on the expression of the amelogenin genes in male developing tooth buds showed that both the AMGX and AMGY genes are transcriptionally active and encode potentially functional proteins. We have isolated genomic and cDNA clones from both the AMGX and AMGY loci and have studied the sequence organization of these two genes. Reverse transcriptase (RT)PCR amplification of the 5' portion of the amelogenin transcripts revealed several alternatively spliced products. The splicing pattern observed in the Y-derived mRNA varies from that of the X-derived mRNA. The promoter regions from both genes and the predicted amelogenin protein sequences are presented. This information will be useful for studying the molecular basis of X-linked amelogenesis imperfecta, for understanding the evolution and regulation of gene expression on the mammalian sex chromosomes, and for investigating the role of amelogenin genes during tooth development.

Amelogenin↗

PubMed1991

Expression of epidermal growth factor in the rat kidney. An immunocytochemical and in situ hybridization study.

The renal localization and the site of synthesis of epidermal growth factor (EGF) were investigated in the rat kidney by immunohistochemistry and in situ hybridization techniques. EGF was localized in the cells of the thick ascending limb of Henle (TAL) and distal convoluted tubule (DCT). At the ultrastructural level, EGF immunoreactivity was distributed on the apical membrane and trans-Golgi complex of the TAL and DCT cells. These segments of the rat nephron also hybridized to prepro-EGF cRNA probes in a specific manner, indicating that TAL and DCT are the sites of EGF synthesis in the rat kidney.

Animals↗

PubMed1991

Testis-specific transcripts of rat farnesyl pyrophosphate synthetase are developmentally regulated and localized to haploid germ cells.

A rat farnesyl pyrophosphate (FPP) synthetase cDNA was used to study the expression of FPP synthetase mRNA levels during spermatogenesis in the rat. RNA blot analysis showed an increase in the level of FPP synthetase transcripts during postnatal development of rat testes. The increase is due to the appearance of longer testis-specific FPP synthetase transcripts as assayed by primer extension mapping. In situ hybridization analysis of adult rat testis sections with an FPP synthetase antisense probe showed that FPP synthetase mRNA levels are greatly enriched in the haploid round spermatidis at stages 7 to 8 of the seminiferous epithelium. These results show that FPP synthetase transcripts in testis are expressed at high levels in haploid male germ cells in a stage-specific manner.

Animals↗

PubMed1990

Identification of pro-epidermal growth factor and high molecular weight epidermal growth factors in adult mouse urine.

By use of immunoblot analysis, we demonstrate the presence of a pro-Epidermal growth factor (EGF) with an approximate molecular weight of 165 kDa in adult mouse urine. In addition, urine contains four high molecular weight EGFs with approximate molecular weights of 116, 97, 66 and 56 kDa. The 165 kDa pro-EGF as well as the 66 and 56 kDa EGFs also are detectable in mouse kidney extract. Neither urine nor kidney contain the mature EGF of 6 kDa. The 165 kDa pro-EGF is the major product synthesized in renal tissue and secreted in urine. The finding of high molecular weight EGFs in urine suggests that part of pro-EGF secreted into urine undergoes partial proteolysis distal to its site of synthesis.

Animals↗

PubMed1990

Expression of epidermal growth factor in the kidney and submandibular gland during mouse postnatal development. An immunocytochemical and in situ hybridization study.

Earlier work has demonstrated that the salivary glands and kidneys are the major sites of epidermal growth factor (EGF) synthesis in adult mice. The precise timing of the onset of endogenous EGF synthesis in these tissues is not yet clear. In the present study we assessed the ontogenesis of EGF expression in the Swiss-Webster mouse. Paraformaldehyde-fixed frozen sections of neonatal kidneys and salivary glands were probed with proEGF cRNA labelled with 35S for in situ hybridization and with rabbit antisera to mouse EGF for immunocytochemistry. Both EGF mRNA and immunoreactivity were first detected in the developing distal nephron between days 3 and 5 postpartum. Juxtamedullary nephrons underlying the superficial nephrogenic zone were the first to express EGF. During the 2nd week after birth, EGF-expressing tubules became more abundant and distributed to medullary as well as cortical regions, corresponding to the thick ascending limb of Henle and distal convoluted tubule. Initial EGF mRNA and immunoreactivity in the submandibular gland were first detected between days 18 and 20 postpartum and increased notably during the following weeks.

Animals↗

PubMed1990

Effect of thyroxine administration on the expression of epidermal growth factor in the kidney and submandibular gland of neonatal mice. An immunocytochemical and in situ hybridization study.

The effect of T4 administration on epidermal growth factor (EGF) expression in kidney and submandibular glands (SMG) was studied in newborn mice. EGF messenger RNA (mRNA) abundance and EGF immunoreactivity were assessed by in situ hybridization and immunohistochemical techniques, respectively. T4 treatment on days 0-6 augmented both the in situ hybridization and immunocytochemical signals in kidney but not in SMG on day 7. By contrast, T4 injections on days 7-14 did not alter the in situ hybridization or immunocytochemical signals in kidney but increased both signals in SMG on day 15. Thus, neonatal T4 treatment augments the levels of EGF mRNA as well as EGF immunoreactivity in both kidney and SMG. The T4 effect is manifested during the first week in kidney whereas the SMG responds to T4 treatment only during the second week of life.

Aging↗

PubMed1990

Steroid sulfatase expression in human placenta: immunocytochemistry and in situ hybridization study.

Steroid sulfatase (STS), an important enzyme in the pathway of estrogen synthesis from sulfated steroid precursors, was localized to the syncytial trophoblast of human placentas during different periods of pregnancy by using a mouse monoclonal antibody and immunocytochemical techniques. Preembedding immunoelectron microscopy revealed STS immunoreactivity associated with the rough endoplasmic reticulum of the syncytial trophoblast. STS mRNA was also localized to this outermost layer of the human trophoblast. At a cellular level, both STS message and immunoreactivity seemed to be more abundant during the late first and early second trimesters than in term placentas. Although the syncytial trophoblast is known to originate from the cytotrophoblast, neither STS immunoreactivity nor STS mRNA was detected in the cytotrophoblast at any stage of placental development studied.

Arylsulfatases↗

PubMed1989

Epidermal growth factor and the kidney.

Current information indicates that the mammalian kidney is a significant site of EGF synthesis, second only to the salivary gland in the rodent and probably exceeding most other tissues in the human species. The prepro EGF mRNA is localized to the cells of the TALH and the DCT. The EGF mRNA transcript in kidney is similar to that in salivary gland; the molecular mass of the prepro EGF protein in kidney approximates 130,000 kDa. Several EGF peptides are excreted in urine, including 6000-molecular weight peptides (composed of EGF 1-53, 1-52, 1-51, and 1-50) and a 30,000-molecular weight species with an aminoterminus portion corresponding to amino acids 829-848 of the prepro molecule. It has been suggested that prepro EGF could be a membrane protein since it contains an internal hydrophobic domain (amino acids 1039-1058) adjacent to the EGF sequence (amino acids 976-1029). The 30,000-molecular weight urinary product appears to represent a protein derived from amino acids 829 to approximately 1029 of prepro EGF, adjacent (distal) to the hydrophobic domain. Moreover, immunoelectron microscopy localizes the EGF immunoreactivity to the apical plasma membrane of the TALH and DCT cells. The molecular form of this apically localized, EGF immunoreactivity is not yet clear. Proximal, distal, and TALH cells of the renal tubules and renal medullary interstitial cells appear to have EGF receptors and respond to EGF with increased DNA synthesis and mitogenesis. Also, there is a relatively late increase in prepro EGF mRNA levels in TALH and DCT cells during the process of renal hypertrophy. Limited evidence suggests a role of EGF on tubular function mediated via basal EGF receptors. EGF peptides processed intracellularly or by membrane localized peptidases appear to be continuously excreted and secreted into urine from the apical membrane surface of the TALH and DCT cells. This urinary EGF is constantly bathing urinary tract epithelial surfaces and could play a role in maintaining surface integrity. A similar role for salivary gland EGF in saliva has been proposed for the gastrointestinal tract. It also is possible that prepro EGF is anchored in the apical membrane, where it could function as a receptor, and a role for renal tubular EGF in regulation of membrane transport events has been proposed.

Animals↗

PubMed1989

In situ hybridization of prepro-epidermal growth factor mRNA in the mouse kidney.

The presence of prepro-epidermal growth factor (prepro-EGF) mRNA was studied in the mouse kidney by in situ hybridization using [3H]prepro-EGF cDNA and 35S-labeled prepro-EGF cRNA probes. In addition, anti-EGF serum was utilized to immunolocalize the peptide by the avidin-biotin complex immunoperoxidase method. Both EGF immunoreactivity and prepro-EGF mRNA hybridization were localized to the thick ascending limb of Henle (TAL) and the distal convoluted tubule (DCT), whereas the macula densa was negative. The glomerulus, the proximal portion of the nephron, and the collecting system were negative. Computer-assisted image analysis of the optical density of the autoradiographic and immunocytochemical signals were performed. The medullary TAL expressed significantly less prepro-EGF than the cortical TAL and the DCT.

Animals↗

PubMed1988

In situ hybridization of nerve growth factor mRNA in the mouse submandibular gland.

We studied the presence of beta-nerve growth factor (NGF) mRNA in the submandibular gland of the mouse by in situ hybridization using 35S-labeled prepro-beta-NGF antisense RNA. Female and male mice were studied at different stages of postnatal development, ranging from 3 to 12 weeks. Although NGF mRNA was detectable in the granular convoluted tubules of the submandibular gland in all the age and sex groups studied, the abundance of the signal dramatically increased after 5 weeks during the development of the submandibular gland. In addition, a conspicuous sexual dimorphism became increasingly apparent in the 6-, 7-, 10-, and 12-week-old animals, due to the remarkable development of the granular convoluted tubules in the adult male mouse, that expressed abundant NGF mRNA.

Animals↗

PubMed1987

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.

Animals↗

PubMed1986

Immunocytochemical localization of nerve growth factor in mouse kidney.

The presence of NGF in mouse kidney was investigated using immunocytochemical methods. Female and male adult Swiss-Webster mouse kidneys were fixed by perfusion with 4% paraformaldehyde or Zamboni's fixative. The kidneys were frozen, and serial sections were prepared. Rabbit NGF antiserum was used for the primary incubation, and the avidin-biotin complex immunoperoxidase procedure was utilized for immunostaining. NGF immunoreactivity was localized in the apical and perinuclear cytoplasm of cells lining the late distal nephron, in a portion that corresponds to the connecting tubule. This portion of the nephron has been consistently observed in close anatomical relationship with arterioles, which are known to be richly innervated. Some cells of the connecting tubule, corresponding to intercalated cells, lacked NGF immunoreactivity.

Animals↗

PubMed1986

Immunocytochemical localization of epidermal growth factor in mouse kidney.

Epidermal growth factor (EGF) was originally isolated from mouse submandibular glands (SMG). However, SMG removal failed to lower circulating EGF, and large amounts of EGF have been found in mouse urine. In addition, the presence of pre-pro-EGF mRNA in mouse kidney has recently been reported by others. Kidneys may therefore represent an alternate source of EGF. In the present study, we investigated the immunocytochemical localization of EGF in mouse kidney. Male and female adult Swiss Webster mice were fixed by perfusion with 4% paraformaldehyde or Zamboni's fixative, the kidneys were frozen, and serial sections were obtained. Rabbit EGF antiserum was used for the primary incubation and the avidin-biotin complex immunoperoxidase procedure was utilized for immunostaining. EGF was immunolocalized in the apical portion of the cells lining the thick ascending limb of Henle (TALH) and the distal convoluted tubule (DCT). The macula densa, in contrast, lacked EGF immunoreactivity. No sex differences were observed in the distribution pattern or intensity of immunostaining. Infusion of EGF into sheep renal artery has been reported to induce changes in urine flow and ionic composition. Immunolocalization of EGF in the TALH and DCT documented here supports a regulatory role for EGF in the function of the mouse distal nephron.

Animals↗

PubMedDate not supplied

Immunoelectron microscopy of epidermal growth factor in mouse kidney.

We recently have reported the immunolocalization of epidermal growth factor (EGF) in mouse kidney by light microscopy. In the present study, we have investigated the ultrastructural localization of EGF by the preembedding immunoperoxidase method for electron microscopy. EGF immunoreactivity was present on the apical plasma membrane of the cells of the thick ascending limb of Henle and the distal convoluted tubule. The macula densa, by contrast, lacked immunoreactivity. Based on functional evidence, a possible regulatory role for EGF in the membrane transport in the distal nephron has been suggested.

Animals↗