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Biomedical subjects

F Keeley

Publications and source records attributed to F Keeley.

5 recordsLinked to original sources
PubMed2000

Synthesis of extracellular matrix and adhesion through beta(1) integrins are critical for fetal ventricular myocyte proliferation.

Extracellular matrix (ECM) regulates vascular smooth muscle cell proliferation. The role of ECM in myocardial growth is unexplored. We sought to determine whether human fetal ventricular myocytes (HFVMs) produce ECM and whether synthesis and attachment to ECM are necessary for their epidermal growth factor (EGF)-dependent and -independent proliferation. Cultured HFVMs proliferate in the presence but not absence of serum and EGF, as determined by increase in cell number and [(3)H]thymidine and [(14)C]leucine incorporation (measures of DNA and protein synthesis, respectively). Using a cyanogen bromide digestion technique to measure collagen and elastin and using affinity chromatography for fibronectin, we found that HFVMs synthesized collagen and fibronectin but not elastin. HFVMs grown on exogenous ECM (including fibronectin and type I collagen and laminin) demonstrated no change in proliferation or DNA and protein synthesis with or without EGF. However, inhibition of collagen synthesis using cis-4-hydroxyproline resulted in a decrease in EGF-related HFVM proliferation and DNA and protein synthesis, which was reversed by exposure to L-proline but not by growth on type I collagen. Use of beta(1) but not beta(3) integrin antibody to inhibit cell interaction with ECM resulted in a decrease in HFVM proliferation and DNA and protein synthesis in response to EGF. Furthermore, EGF-dependent proliferation was enhanced by alpha(1)beta(1) and alpha(5)beta(1) antibodies that act as functional ligands, but not alpha(3)beta(1), the only beta(1) subtype expressed in adult myocytes. In conclusion, proliferating HFVMs synthesize collagen and fibronectin. The proliferative response of HFVMs to EGF requires the synthesis of collagen as well as attachment to specific alpha/beta(1) integrin heterodimers.

Apoptosis↗
PubMed1993

The 67-kD elastin/laminin-binding protein is related to an enzymatically inactive, alternatively spliced form of beta-galactosidase.

We and others have previously shown that a 67-kD cell surface elastin/laminin-binding protein (EBP) is responsible for cell adhesion to elastin and laminin and for mediating the process of elastin fiber assembly, but the nature of this protein was unknown. In this report we provide evidence that a 67-kD catalytically inactive form of beta-galactosidase produced by alternative splicing demonstrates immunological and functional similarity and sequence homology to the 67-kD EBP, suggesting that the two might be the same. Antibody prepared to a synthetic peptide, N-Ac-GSPSAQDEASPL, corresponding to a frame-shift-generated sequence unique to the alternatively spliced form of human beta-galactosidase, also recognized sheep EBP both on Western blotting and in aortic tissue. Furthermore, this synthetic peptide (S-GAL) binds to elastin and laminin, but not to fibronectin, collagen I, or collagen III. Moreover, both tropoelastin and laminin which bind to S-GAL peptide affinity columns can be specifically eluted from them with an excess of free S-GAL peptides. In addition, sequence homology among this splice variant of human beta-galactosidase, sheep EBP, and NH2-terminal sequences of some elastases suggests that these proteins share a common ligand-binding motif that has not been previously recognized.

Alternative Splicing↗
PubMed1991

Impaired elastin fiber assembly related to reduced 67-kD elastin-binding protein in fetal lamb ductus arteriosus and in cultured aortic smooth muscle cells treated with chondroitin sulfate.

In the fetal ductus arteriosus (DA) disruption in the assembly of elastin fibers is associated with intimal thickening and we previously reported that fetal lamb DA smooth muscle cells incubated with endothelial conditioned medium produce two-fold more chondroitin sulfate (CS) compared with aorta (Ao) cells (Boudreau, N., and M. Rabinovitch. 1991. Lab. Invest. 64:187-199). We hypothesized that CS or dermatan sulfate (DS), both N-acetylgalactosamine glycosaminoglycans (GAGs), may be similar to free galactosugars in causing release of the 67-kD elastin binding protein (EBP) from the smooth muscle cell surfaces and impaired elastin fiber assembly. Using immunohistochemistry, immunoelectron microscopy, and western immunoblot we demonstrated a reduction in the 67-kD EBP in fetal lamb DA smooth muscle in tissue and in cultured cells. Also, reduced EBP was observed in fetal lamb and neonatal rat Ao smooth muscle cells incubated with N-acetylgalactosamine GAGs, CS, and DS, but not with N-acetylglucosamine containing GAGs, heparan sulfate (HS), or hyaluronan. Reduction in EBP was related to shedding from cell surfaces into the conditioned medium. This was associated with impaired elastin fiber assembly in cultured cells, assessed both morphologically and by a relative increase in tropoelastin and decrease in desmosines. The EBP extracted from smooth muscle cell membranes binds to an elastin affinity gel and can be eluted from it with CS but not with HS. Moreover, the amount of EBP extractable from smooth muscle cell membranes correlated with the morphologic assessment. We propose that increased CS or DS, may impair assembly of newly synthesized elastin in the media of the ductus arteriosus associated with the development of intimal thickening.

Animals↗
PubMed1990

Perforation of the colon in a 15-year-old girl with Ehlers-Danlos syndrome type IV.

A 15-year-old girl presented with severe fecal peritonitis due to a large spontaneous colonic perforation. The sigmoid colon was the site of a cluster of white serosal lesions with omental adhesions, of an appearance identical to that of the edges of the perforation. Her father had died at 30 years of age of spontaneous rupture of an iliac artery aneurysm, preceded by rupture of a splenic artery aneurysm and a spontaneous carotid-cavernous fistula. The clinical diagnosis of Ehlers-Danlos syndrome type IV was made, and confirmed by demonstrating that the patient's cultured fibroblasts are not producing or secreting type III collagen. Spontaneous perforation of the colon is a well-described complication of this syndrome, with a high incidence of recurrence. We recommend total abdominal colectomy to minimize the latter possibility.

Adolescent↗