Biomedical subjects

G Gabbiani

Publications and source records attributed to G Gabbiani.

At least 163 records · Page 9Linked to original sources

PubMed1989

Alpha-smooth muscle actin, a differentiation marker of smooth muscle cells, is present in microfilamentous bundles of pericytes.

alpha-Smooth muscle (alpha-sm) actin, an isoform typical of smooth muscle cells (SMC) and present in high amounts in vascular SMC, was demonstrated in the cytoplasm of pericytes of various rat and human organs by means of immunocytochemistry at the electron microscopic level. In SMC and pericytes, alpha-sm actin was localized in microfilament bundles, strengthening the assumption that it is the functional isoform in these cell types and supporting the assumption that pericytes exert contractile functions.

Actin Cytoskeleton↗

PubMed1989

Alpha-smooth muscle actin in parenchymal cells of bleomycin-injured rat lung.

Bleomycin causes focally diffuse interstitial fibrosis characterized by increases in the number and volume of contractile filament-laden parenchymal cells, as well as increased parenchymal contractility. However, the origin of these cells and their relationship to altered contractility, remain unknown. We now have used immunohistochemical methods to ask if cells containing smooth muscle actin and myosin are present in involved regions of parenchyma. Staining of the parenchyma of control lungs with a monoclonal antibody against alpha-smooth muscle actin is sparse, consisting of reactivity with the alveolar entrance ring (septal tip) cells as well as occasional reactivity of alveolar wall cells that may represent pericytes or contractile interstitial cells. Increased alpha-smooth muscle actin staining was observed in areas of parenchymal damage in lungs from animals sacrificed between 1 and 4 weeks postbleomycin instillation. This reactivity included altered staining of the airway and vessel smooth muscle coat as well as thickened septal tips. In addition, newly reactive cells were observed in interstitial and intraalveolar regions and in bands of thickened submesothelial tissue. Staining was most intense in the focal fibrotic lesions which are characteristic of this injury. By contrast, parenchymal reactivity with a polyclonal antibody against smooth muscle myosin at the later time points shows only a mild increase in punctate staining in the damaged foci. We hypothesize that the substantial increase in alpha-smooth muscle actin containing cells in fibrotic regions of involved parenchyma after bleomycin injury is responsible for the altered morphologic, biochemical, and mechanical properties that we have observed.

Actins↗

PubMed1989

The cytoskeleton of arterial smooth muscle cells during development, atheromatosis, and tissue culture.

Arterial smooth muscle cells (SMCs) assume cytoskeletal features of embryonic cells during human and experimental atheromatosis, as well as when placed in culture. The expression of alpha-smooth muscle (SM) actin can be used to monitor these changes. The synthesis of alpha-SM actin is decreased early after plating in cultured cells and early after endothelial lesion in animals. The amount of mRNA for alpha-SM actin is not affected in cultured cells, although it is drastically decreased in the carotid artery after endothelial injury. Heparin does not modify in vivo the early decrease of alpha-SM actin mRNA and synthesis, but, by inhibiting the entry of SMC into the S phase of the cell cycle, it produces an early reinduction of alpha-SM actin.

Animals↗

PubMed1989

Gelsolin modulation in epithelial and stromal cells of mammary carcinoma.

Gelsolin, a Ca2+-sensitive protein present in many mammalian cells, regulates actin filament length by multiple mechanisms. In tumor cells, increased amounts of F-actin without change in its total amount have been observed, suggesting a modification in the organisation of this protein. The authors have localized gelsolin, total actin, alpha-smooth muscle actin, and prekeratin in frozen sections of normal human breast and infiltrating duct carcinomas by immunohistochemistry. A positive staining for gelsolin was observed in normal epithelial and myoepithelial cells but not in stromal fibroblasts. In contrast, no staining for gelsolin was detectable in carcinomatous cells, with the exception of remaining myoepithelial cells; myofibroblasts of the stromal reaction displayed an intense positive reaction. The absence of gelsolin staining in the epithelial cells of breast carcinoma may reflect their dedifferentiation or proliferative and invasive activities. The appearance of gelsolin in stromal cells raises the question as to what is its function in this situation. The immunohistochemical detection of gelsolin may be a useful adjunct to the study of mammary gland epithelium malignant transformation.

Breast↗

PubMed1989

Myofibroblasts from diverse pathologic settings are heterogeneous in their content of actin isoforms and intermediate filament proteins.

We examined by immunofluorescence the distribution of vimentin, desmin, alpha-smooth muscle actin and alpha-sarcomeric actin in normal human soft tissues and in pathologic tissues containing myofibroblasts, including normally healing granulation tissue, hypertrophic scar, and fibromatosis. The pattern of actin isoforms was also documented biochemically by two-dimensional gel electrophoresis. Fibroblastic and/or myofibroblastic cells in each setting always expressed vimentin and never alpha-sarcomeric actin. Moreover, these cells showed an heterogeneous cytoskeletal composition which defined four phenotypes: (a) cells expressing only vimentin; (b) cells expressing vimentin, alpha-smooth muscle actin and desmin; (c) cells expressing vimentin and alpha-smooth muscle actin; and (d) cells expressing vimentin and desmin. Given this, two groups of lesions are distinguished: the first contains only vimentin cells and consists of normally healing granulation tissue, eschars and normally healed scars; the second contains vimentin cells admixed with variable proportions of vimentin, alpha-smooth muscle actin and desmin, vimentin and alpha-smooth muscle actin, and vimentin and desmin cells and consists of hypertrophic scars and fibromatoses. Immunogold electron microscopy showed that alpha-smooth muscle actin was present in a proportion of cells with ultrastructural features of myofibroblasts. Our findings suggest that contrary to myofibroblasts of normally healing granulation tissue and normally healed scars, myofibroblasts of pathologic conditions characterized by chronic retraction express always immunochemical features indicative of smooth muscle differentiation.

Actins↗

PubMed1989

Expression of actin isoforms and intermediate filament proteins in childhood orbital rhabdomyosarcomas.

The diagnosis of orbital rhabdomyosarcoma (RMS) in childhood gives rise to several clinical and anatomo-pathological problems. Antibodies recognizing structural proteins and cytoskeletal components have been shown to increase the diagnostic accuracy of different neoplastic lesions. In this study we examined anatomo-clinically and, where possible, by means of immunohistochemistry and electron microscopy, a series of 14 cases of orbital RMS in childhood. In the 12 cases studied by immunohistochemistry, desmin was always present, although showing variable patterns, and alpha-sarcomeric actin was found in 10 cases. alpha-Smooth muscle actin was always absent. The other markers tested (myoglobin, polyclonal actin, vimentin and enolase) proved unreliable for several reasons. We conclude that antibodies against desmin and alpha-sarcomeric actin are useful for the diagnostic definition of RMS. In addition, immunohistochemical analysis supplies data regarding the degree of tumor differentiation and may be applied to monitor radio- and chemotherapy.

Actins↗

PubMed1988

Smooth-muscle differentiation in stromal cells of malignant and non-malignant breast tissues.

A mouse monoclonal antibody (MAb) recognizing alpha-smooth-muscle actin has been used to study smooth-muscle differentiation features in the stromal cells of desmoplastic reactions accompanying mammary tumors. We have studied, by the same immunohistochemical technique, a series of malignant and non-malignant human breast tissues. Cells composing the desmoplastic reaction were found to express alpha-smooth-muscle actin in all the 11 breast carcinomas examined, whereas no immunostain was demonstrated in the stromal cells of 7 breast tissue samples histologically defined as normal. Three of 9 cases of fibrocystic disease showed a minority of positively stained stromal cells, generally in association with epithelial hyperplasia. All the 7 cases of sclerosing adenosis, 3 of 4 cases of diffuse papillomatosis and all 3 intraductal papillomas exhibited a majority of immunoreactive stromal cells. Numerous stromal cells in 3 of 11 circumscribed fibroadenomas analyzed expressed low amounts of alpha-smooth-muscle actin. The factor(s) responsible for smooth-muscle differentiation in stromal cells are presently unknown, but the detection of this previously unsuspected stromal cell phenotype in nonmalignant mammary tissues might help in characterizing the variant morphological aspects designated under the label "fibrocystic disease" and in understanding the biology of premalignant or early malignant lesions of the breast.

Actins↗

PubMed1988

Correlation between the distribution of smooth muscle or non muscle myosins and alpha-smooth muscle actin in normal and pathological soft tissues.

The distribution of smooth muscle (SM) and non muscle myosins was compared with that of alpha-SM actin in various normal and pathological tissues and in cultured cells by means of indirect immunofluorescence using a monoclonal antibody specific for alpha-SM actin [anti-alpha sm-1, Skalli et al., 1986b] and two polyclonal antibodies raised against bovine aortic myosin (ABAM) and human platelet myosin (AHPM), respectively. In normal tissues ABAM stained vascular and parenchymal smooth muscle cells (SMC), myoepithelial cells and myoid cells of the testis in a pattern similar to that reported by other authors with antisera raised against non vascular SM myosin. Cells stained with ABAM were always positive for anti-alpha sm-1. In human and experimental atheromatous plaques, most cells were positive for AHPM; a variable proportion was also stained for ABAM plus anti-alpha sm-1. Myofibroblasts from rat granulation tissue, Dupuytren's nodule and stroma from breast carcinoma were constantly positive for AHPM and negative for ABAM; however, myofibroblasts from Dupuytren's nodule and breast carcinoma were anti-alpha sm-1 positive. Early primary cultures of rat aortic SMC were positive for ABAM and anti-alpha sm-1 and became negative for ABAM and positive for AHPM after a few days in culture. They remained positive for AHPM and anti-alpha sm-1 after passages; the staining of AHPM and anti-alpha sm-1 appeared to be colocalized along the same stress fibers. These results may be relevant for the understanding of SMC function and adaptation, and show that in non malignant SMC proliferation, alpha-SM actin represents a more general marker of SM origin than SM myosin.

Actins↗

PubMed1988

Characterization of actin isoforms in ejaculated boar spermatozoa.

Actin was localized in boar ejaculated spermatozoa by using specific antisera against cytoplasmic isoforms of actin [Otey et al., J Cell Biol, 102:1726-1737, 1986; Skalli et al., J Cell Biol, 103:2787-2796, 1986; Miller et al., Biochemistry, 26:6064-6070, 1987]. Indirect immunofluorescence and immunoelectron microscopy showed that gamma and beta actins were codistributed in the acrosomal and postacrosomal regions. Sperm actin was also identified on two-dimensional gel as two spots in the isoelectric point and molecular weight corresponding to beta and gamma actins. Coelectrophoresis of sperm actin and chicken gizzard actin and immunoblots stained with the specific antibodies confirmed the presence of these two isoforms of actin.

Actins↗

PubMed1988

Distribution of cytoskeletal and contractile proteins in normal and tumour bearing salivary and lacrimal glands.

We have evaluated by means of immunocytochemistry the distribution of various cytoskeletal and contractile proteins (cytokeratins, vimentin, desmin and alpha-smooth muscle actin) in 23 salivary or lacrimal gland primary tumours (15 pleomorphic adenomas and 8 carcinomas in pleomorphic adenoma), one third of which contained areas of normal gland. Normal epithelial luminal cells were stained by cytokeratin antibodies with a general specificity, while myoepithelial cells were selectively stained by a monoclonal antibody (SK2-27) reacting in immunoblots with cytokeratin polypeptides 14, 16 and 17, according to the classification of Moll et al. (1982) and by an antibody directed against alpha-smooth muscle actin (Skalli et al. 1986). In pleomorphic adenomas, both epithelial and myoepithelial cells displayed typical topographic distributions; moreover, myoepithelial cells showed two distinct cytoskeletal phenotypes. These findings could account in part for the heterogeneity of aspects observed in this tumour. In carcinomas, malignant cells were always positive to cytokeratin antibodies with general specificity and myoepithelial cells were absent as judged by anticytokeratin SK2-27 and anti-alpha-smooth muscle actin immunostainings. However, interestingly, there was in all cases a strong positivity for alpha-smooth muscle actin in stromal cells, similarly to what has previously been described for mammary carcinoma (Skalli et al. 1986). Our findings may be useful for the interpretation of the histogenesis of salivary and lacrimal tumour and stromal cells.

Adenoma, Pleomorphic↗

PubMed1988

The intraclonal and interclonal phenotypic heterogeneity in a rhabdomyosarcoma cell line with abortive imitation of embryonic myogenesis.

Three distinct subpopulations (A, B, C) derived from a dimethylbenzanthracene-induced rat rhabdomyosarcoma were established as permanent cell lines. Although the clonal nature of each of these subpopulations was confirmed by repeated recloning procedures, a striking intraclonal phenotypic heterogeneity was observed. By means of immunofluorescence microscopy and transmission electron microscopy, it could be shown that these subpopulations closely recapitulate stages of embryonic rhabdomyogenesis both in vitro and in vivo, but differ in their particular range of maximum differentiation. Embryonic rhabdomyogenesis is imitated most perfectly by subpopulation C, in which multinuclear myotubes are formed in vitro by fusion of mononuclear cells, and alpha-sarcomeric actin is expressed in the multinuclear cells and in a few mononuclear cells. After retransplantation in vivo, subpopulation C further proceeds in fine structural differentiation, now exhibiting myofibrils with a sarcomeric organization in the myotube-like giant cells. The cells of subpopulation B do not exceed the stage of mononuclear desmin-positive cells in vitro, but synthesize thin and thick myofilaments after retransplantation in vivo. The cells of subpopulation A recapitulate embryonic rhabdomyogenesis least successfully being confined to the stage of mononuclear desmin-positive cells. Thus, the coexistence of diverse subpopulations and the cellular maturation within these subpopulations together contribute to the phenotypic heterogeneity of rhabdomyosarcomas.

Animals↗

PubMed1988

Localization of T lymphocytes and macrophages in fibrous and complicated human atherosclerotic plaques.

The cellular composition of aortic atherosclerotic plaques was analyzed by immunocytochemistry using cell type-specific monoclonal antibodies. T lymphocytes and monocytes/macrophages were detected both in early, fibrous plaques, and in more advanced, complicated ones. Many smooth muscle cells in these plaques expressed the class II MHC antigen, HLA-DR. Since this antigen is inducible by T cell products, our findings suggest that T cell-smooth muscle interactions occur during atherogenesis.

Antibodies, Monoclonal↗

PubMed1988

Arterial smooth muscle cells in vivo: relationship between actin isoform expression and mitogenesis and their modulation by heparin.

Quiescent smooth muscle cells (SMC) in normal artery express a pattern of actin isoforms with alpha-smooth muscle (alpha SM) predominance that switches to beta predominance when the cells are proliferating. We have examined the relationship between the change in actin isoforms and entry of SMC into the growth cycle in an in vivo model of SMC proliferation (balloon injured rat carotid artery). alpha SM actin mRNA declined and cytoplasmic (beta + gamma) actin mRNAs increased in early G0/G1 (between 1 and 8 h after injury). In vivo synthesis and in vitro translation experiments demonstrated that functional alpha SM mRNA is decreased 24 h after injury and is proportional to the amount of mRNA present. At 36 h after injury, SMC prepared by enzymatic digestion were sorted into G0/G1 and S/G2 populations; only the SMC committed to proliferate (S/G2 fraction) showed a relative slight decrease in alpha SM actin and, more importantly, a large decrease in alpha SM actin mRNA. A switch from alpha SM predominance to beta predominance was present in the whole SMC population 5 d after injury. To determine if the change in actin isoforms was associated with proliferation, we inhibited SMC proliferation by approximately 80% with heparin, which has previously been shown to block SMC in late G0/G1 and to reduce the growth fraction. The switch in actin mRNAs and synthesis at 24 h was not prevented; however, alpha SM mRNA and protein were reinduced at 5 d in the heparin-treated animals compared to saline-treated controls. These results suggest that in vivo the synthesis of actin isoforms in arterial SMC depends on the mRNA levels and changes after injury in early G0/G1 whether or not the cells subsequently proliferate. The early changes in actin isoforms are not prevented by heparin, but they are eventually reversed if the SMC are kept in the resting state by the heparin treatment.

Actins↗

PubMed1988

Alveolar soft part sarcoma: immunological evidence of rhabdomyoblastic differentiation.

Two cases of alveolar soft part sarcoma have been studied immunocytochemically using antisera against epithelial membrane antigen, lysozyme, keratins, S-100 protein, desmin, vimentin, fetal myosin, slow myosin, alpha-skeletal muscle actin, alpha-smooth muscle actin and myoglobin. The neoplastic cells were negative with all antisera employed with the exception of the alpha-skeletal muscle actin antiserum which stained the cytoplasm of numerous neoplastic elements, including the crystalloid rods, typical cytoplasmic inclusions of these tumours. It is suggested that the presence of this protein indicates rhabdomyoblastic differentiation of these tumours.

Actins↗

PubMed1988

Alpha-smooth muscle actin is transiently expressed in embryonic rat cardiac and skeletal muscles.

Actin isoform expression may change during development, and in certain physiological, experimental and pathological situations. It is accepted that during sarcomeric (skeletal and cardiac) muscle development, the alpha-skeletal and alpha-cardiac isoforms of actin accumulate rapidly at the onset of muscle fibre formation, while there is a rapid fall in the expression of nonmuscle (beta and gamma) actin isoforms. Here we show that, before birth, both skeletal and myocardial cells express significant amounts of alpha-smooth muscle actin mRNA and protein. This expression is transient and disappears over the 1-7 days following birth. Our findings show that the program regulating actin isoform expression in sarcomeric muscle development is complex and that alpha-smooth muscle actin participates in this process.

Actins↗

PubMed1988

Specific demonstration of myoepithelial cells by anti-alpha smooth muscle actin antibody.

The myoepithelial cells of the sweat, mammary, tracheobronchial, and salivary glands are specifically identified by monoclonal antibody alpha-SM-1, which recognizes alpha smooth muscle actin and not the other actin isoforms. Basal or "reserve" cells in the stratified epithelia and excretory ducts of the salivary glands are negative, as well as all other epithelial cells in various organs. The reaction can be performed in routinely fixed and embedded tissues and is of practical interest in diagnostic histopathology. In immunoelectron cytochemistry, alpha-SM-1 antibody binds to the microfilament bundles in myoepithelial cells of the breast, but does not stain luminal cells and occasional basally located epithelial cells. These basal cells are morphologically and immunocytochemically distinct from the myoepithelial cells, and their nature and significance remain to be clarified.

Actins↗

PubMed1988

Chemically induced rhabdomyosarcomas in rats. Ultrastructural, immunohistochemical, biochemical features and expression of alpha-actin isoforms.

A series of 14 primary and two metastatic rat rhabdomyosarcomas (RMS) induced with nickel sulfide was studied by light microscopy, transmission electron microscopy, indirect immunofluorescence, avidin-biotin-peroxidase immunohistochemistry and two-dimensional gel electrophoresis. Monoclonal or affinity-purified polyclonal antibodies were used for the immunohistochemical demonstration of vimentin, desmin, alpha-smooth muscle (alpha-sm) actin and alpha-sarcomeric (alpha-sr) actin. By histological and ultrastructural studies, four categories of RMS were diagnosed on the basis of the neoplastic cell types. These were: (1) well-differentiated RMS (n = 2), (2) pleomorphic RMS (n = 8), (3) embryonal RMS (n = 4), and (4) embryonal myosarcomas (n = 2). Immunohistochemically, all these neoplasms expressed desmin and alpha-sr actin, reflecting their rhabdomyoblastic origin. Two dimensional gel electrophoresis performed on five neoplasms demonstrated alpha, beta and gamma actins spots in all cases. This study demonstrates that the alpha-sr actin antibody represents a good marker for rhabdomyoblastic differentiation is useful in the diagnosis of RMS since it was present in all morphologically confirmed RMS and in two ultrastructurally undifferentiated sarcomas positive for desmin. Neoplastic cells positive for alpha-sm actin were noted in 11 confirmed RMS. Double indirect immunofluorescence showed that all alpha-sm and alpha-sr positive cells also contained desmin. Co-expression of alpha-sr and alpha-sm actins was studied in serial sections of formalin-fixed, paraffin-embedded tumor tissue. Both alpha-sm and alpha-sr actins were localized in some rhabdomyoblasts. This study confirms our previous observations in human tumors and shows, for the first time, that alpha-sr and alpha-sm actins can be present in the same neoplastic cell in vivo.

Actins↗

PubMed1988

Intermediate filament proteins and actin isoforms as markers for soft tissue tumor differentiation and origin. II. Rhabdomyosarcomas.

A series of 15 rhabdomyosarcomas was examined by light microscopy, transmission electron microscopy, two-dimensional gel electrophoresis (2D-GE) and indirect immunofluorescence, the latter using monoclonal or affinity-purified polyclonal antibodies to desmin, vimentin, alpha-smooth muscle and alpha-sarcomeric (alpha-sr) actins. By light microscopy, the authors diagnosed 1 botrioid, 1 alveolar, and 7 embryonal rhabdomyosarcomas, 4 pleomorphic spindle cell sarcomas, and 2 spindle cell sarcomas, one nondistinct, the other with a hemangiopericytomatous pattern. By transmission electron microscopy, 13 neoplasms disclosed rhabdomyoblastic differentiation; the remaining 2, myogenic differentiation. By immunofluorescence microscopy, all neoplasms expressed vimentin and alpha-sr actin, 12 expressed, in addition, desmin, and 1 expressed alpha-smooth muscle actin. Among the 11 neoplasms studied by means of 2D-GE, 7 demonstrated an alpha-actin spot, while 4 showed only beta and gamma spots. One tumor disclosed, in addition to alpha, beta, and gamma spots, a spot with a molecular weight corresponding to actin, but more acidic than alpha-actins. This study demonstrates that alpha-sr actin antibody represents a valuable marker for the diagnosis of rhabdomyosarcoma, because it was present in all neoplasms, including the one negative for desmin. This antibody further allowed the recognition of pleomorphic variants and morphologically atypical forms of rhabdomyosarcomas. The presence of alpha-smooth muscle actin in 1 case of rhabdomyosarcoma suggests that this actin isoform may be expressed during skeletal muscle differentiation.

Actins↗