Abstract: The beta1C integrin is an alternatively spliced variant of the beta1 integrin subfamily that at variance with its wild-type counterpart, i.e., the beta1A integrin, inhibits cell proliferation in prostate cancer cells. We have recently shown that transcriptional, translational and post-translational processes contribute to the selective loss of beta1C integrin during prostate malignant transformation. Here, we investigated whether androgen deprivation therapy (ADT) may affect beta1C mRNA expression in prostate cancer. Neoplastic prostates were obtained from patients undergoing radical prostatectomy who had received neoadjuvant ADT. The beta1C mRNA level was measured by Northern hybridization experiments and compared to normal prostates obtained from patients who underwent radical cystoprostatectomy for bladder cancer. Furthermore, the beta1C integrin gene transcriptional activity was measured by nuclear Run-on assays. We found an increase of beta1C mRNA expression (208+/-11%; p<0.01) in patients who received ADT in comparison to those who did not. Furthermore, we demonstrated an increase of gene transcriptional activity (360+/-10%; p<0.01) possibly partially or completely responsible for the regulation of the beta1C integrin mRNA levels. Short-term administration of ADT seems to interfere with beta1C integrin expression, suggesting the existence of androgen-mediated pathways involving beta1C. Precise characterization of the mechanisms that regulate the expression of this factor in cancer cells will provide further insight into the molecular mechanisms involved in tumor progression and possibly contribute to the identification of molecular targets for the development of new therapeutic strategies.
Abstract: Insulin like-growth factor I (IGF-I) has been involved in the pathogenesis of a variety of human neoplasia due to the mitogenic and anti-apoptotic properties of its cognate receptor. In human thyroid carcinomas, we have previously documented an increased immunoreactivity of both IGF-I and the IGF-I receptor (IGF-I R) associated with up regulation of IGF-I mRNA . Immunoreactivity of IGF-I and cognate receptor positively correlated with tumor diameter and wide intrathyroidal extension but not with patient's gender and age or with the stage of the tumors and the occurrence of limph node metastases. Most experimental studies indicate that the effects of IGF-I on target cells are regulated in a complex fashion and depend on the simultaneous occurrence of IGF-IR and the binding proteins.
Abstract: Hypothyroidism decreases liver weight and delays the compensatory liver growth after partial hepatectomy (PH) as compared with the euthyroid condition. The aim of this study was to investigate, in hypothyroid rats, the mRNA expression of genes modulating these effects, focusing on c-fos and c-myc, hallmarks of hepatocyte 'priming', and on transforming growth factor-beta1 (TGF-beta1) and its receptor, the transforming growth factor-beta1 receptor-type II (TbetaR-II), negative regulators of liver growth. Euthyroid and hypothyroid male Wistar rats underwent 70% PH and total RNA was isolated from frozen liver samples removed at basal state and during regeneration, 0-144 h after surgery. In this study, we show for the first time that, in the basal liver state, hypothyroidism increased TGF-beta1 and TbetaR-II mRNA levels by 45% and 30%, respectively, as compared with the euthyroid condition and, after PH, resulted in a approximately 12-h delay in the activation of c-fos and c-myc mRNA expression. Moreover, the increase in TGF-beta1 mRNA levels, detected 24-48 h after PH in euthyroid rats, was delayed by 72 h in hypothyroid rats, occurring when a concomitant reduction in TbetaR-II was measured. These results suggest that, in hypothyroid rats, at the basal liver level, the increase in mRNA expression of genes that negatively regulate liver growth might be involved in the decrease in liver weight and that, after PH, the delay of hepatocyte 'priming' and coordinated changes in mRNA expression of negative regulators of liver regeneration might be involved in delaying the regenerative process.
Abstract: beta1C integrin is a spliced variant of the human beta1 integrin family that inhibits cell proliferation, at variance with beta1A that stimulates it. During the transition from normal to neoplastic endometrium, both variants are down-regulated at the mRNA level, but only beta1C at the protein level, suggesting a key role of the regulation of beta1C integrin expression in the pathogenesis of endometrial cancer. In this study we show for the first time that, besides beta1A and beta1C, the beta1B spliced variant is expressed in human endometrium, and is up-regulated in hyperplastic and neoplastic endometria in comparison with normal proliferative endometria. To investigate the mechanisms of regulation of beta1 integrin expression during endometrial cancer progression we compared the transcriptional activity of the beta1 integrin gene in normal and diseased endometria by nuclear run-on analysis and we found it significantly reduced in endometrial adenocarcinoma. On the contrary, hyperplastic endometria showed a 2-fold increase in the beta1 transcription rate that directly correlated with the increase in beta1B, beta1C and beta1A steady-state mRNA levels. Finally, we compared the activity of the distal and proximal promoters of the beta1 gene integrin gene in normal and diseased endometria and we found the activity of the proximal promoter decreased in neoplastic endometria and increased in hyperplastic tissues, whereas the activity of the distal promoter did not change in different endometrial physio/pathological conditions. These findings suggest a complex pattern for regulation of the expression of beta1 integrin variants during endometrial malignant transformation.
Abstract: The expression pattern of erbB2 and its transmembrane polymorphisms (Ile654Val and Ile655Val) were investigated in a panel of human normal and neoplastic breast cell lines to evaluate whether the expression pattern was affected by changes in the gene structure. At least two peptides of lower molecular mass forms (95 and 68 kDa) than the holoreceptor (185 kDa), comprehensive of the tyrosine kinase domain, were detected in all cells. Both peptides were also phosphorylated, suggesting a functional role in signal transduction. The presence of the polymorphisms found in two cell lines was unrelated to the expression of the lower molecular mass proteins.
Abstract: beta(1C) and beta(1A) integrins are two splice variants of the human beta(1) integrin subfamily that act as an inhibitor and a stimulator of cell proliferation, respectively. In neoplastic prostate epithelium, both these variants are down-regulated at the mRNA level, but only beta(1C) protein levels are reduced. We used an experimental model consisting of PNT1A, a normal immortalized prostate cell line, and LNCaP and PC-3, two prostate carcinoma cell lines, to investigate both the transcription/post-transcription and translation/post-translation processes of beta(1C) and beta(1A). Transcriptional regulation played the key role for the reduction in beta(1C) and beta(1A) mRNA expression in cancer cells, as beta(1C) and beta(1A) mRNA half-lives were comparable in normal and cancer cells. beta(1C) translation rate decreased in cancer cells in agreement with the decrease in mRNA levels, whereas beta(1A) translation rate increased more than 2-fold, despite the reduction in mRNA levels. Both beta(1C) and beta(1A) proteins were degraded more rapidly in cancer than in normal cells, and pulse-chase experiments showed that intermediates and/or rates of beta(1C) and beta(1A) protein maturation differ in cancer versus normal cells. Inhibition of either calpain- or lysosomal-mediated proteolysis increased both beta(1C) and beta(1A) protein levels, the former in normal but not in cancer cells and the latter in both cell types, albeit at a higher extent in cancer than in normal cells. Interestingly, inhibition of the ubiquitin proteolytic pathway increased expression of ubiquitinated beta(1C) protein without affecting beta(1A) protein levels in cancer cells. These results show that transcriptional, translational, and post-translational processes, the last involving the ubiquitin proteolytic pathway, contribute to the selective loss of beta(1C) integrin, a very efficient inhibitor of cell proliferation, in prostate malignant transformation.
Abstract: beta(1C) and beta(1A) integrins are alternatively spliced variants of the human beta(1)-subunit; the former has been shown to inhibit cell proliferation, and the latter to promote it. Although some components of the beta(1) integrin subfamily are expressed in human endometrial and decidual cells during the menstrual cycle and early pregnancy, to date no information is available about the expression of beta(1C) integrin in endometrial and decidual tissues and its possible roles during implantation and pregnancy. To gain further insight on this subject, we have explored beta(1C) integrin expression in endometrial (proliferative, secretory, and atrophic) and decidual (from the first and third trimesters of pregnancy) tissue samples at both gene and protein levels by Northern and Western blotting analyses and by immunohistochemistry. beta(1A) protein levels were also measured in the same tissues as a control. The results of this study demonstrate that both beta(1C)- and beta(1A)-subunits are expressed in the endometrium and decidua. In the former, maximal beta(1C) expression was detected in atrophic endometria, whereas beta(1A) expression levels were increased in secretive and decreased in atrophic endometrial tissues compared with proliferative endometria. In addition, whereas beta(1A) levels were significantly increased in decidual tissues, compared with proliferative endometria, beta(1C) expression was dramatically reduced in the same tissues, thus pointing to selective down-regulation of beta(1C) expression in the decidua. These data suggest that the expression of beta(1C) integrin, a very efficient inhibitor of cell proliferation, may be modulated by the maternal microenvironment and may play a fundamental role in mediating trophoblast outgrowth and migration during pregnancy.
Abstract: Integrins are ubiquitous cell adhesion molecules that are involved in maintaining normal tissue morphology and have been implicated in the aggressive behavior of several malignancies. beta 1C integrin is an alternatively spliced variant of the beta 1A integrin subunit that, at variance with beta 1A, inhibits epithelial cell proliferation. beta 1C integrin is expressed in non-proliferative, benign prostatic epithelium and is down-regulated in prostatic adenocarcinoma. In the current study, we examined beta 1C expression at mRNA and protein levels in 18 endometrial adenocarcinoma and in 20 endometrial hyperplastic tissues, using Northern and Western blotting analysis and immunohistochemistry. The pattern of integrin expression was compared to that of the endometrium of 14 normal cycling women. The results of this study document inhibited beta 1C integrin expression in endometrial adenocarcinoma, both at the mRNA and protein levels, at variance with significantly up-regulated beta 1C mRNA expression in endometrial hyperplasia, in comparison with normal proliferative endometria. Our data suggest a key role of the regulation of beta 1C integrin expression in the pathogenesis of endometrial proliferative diseases: beta 1C integrin may act as growth modulator in cancer cells, playing a role in downstream intracellular signaling.
Abstract: Members of the integrin family of cell adhesion receptors influence several important aspects of cancer cell behaviour, including motility and invasiveness, cell growth and cell survival. beta1C integrin, an alternatively spliced variant of the human beta1 integrin, has been shown to inhibit cell proliferation. We have previously demonstrated that beta1C integrin mRNA and protein are present in normal prostate and are down-regulated in prostate adenocarcinoma. To explore some of the molecular mechanisms regulating beta1C integrin gene expression, we have analysed the transcriptional activity of the beta1 integrin gene in neoplastic and normal human prostate tissue. Run-on analysis demonstrates that the transcription rate of the beta1 integrin gene is significantly reduced in prostate cancer specimens compared to normal prostate, thus accounting for the reduction in mRNA levels of the beta1 integrin variants. Moreover, the decrease in transcriptional activity of the beta1 integrin gene directly correlates to the reduction of beta1C integrin steady-state mRNA levels (r=0.78).
Abstract: Increased concentrations of TGF-beta 1 in endometriotic tissue are considered important in the pathophysiology of endometrial diseases since TGF-beta 1 may inhibit natural killer activity and induce angiogenesis and proliferation of endometrial stromal cells. In the present study we report on TGF-beta 1, IGF-1 and their receptor localization, as detected by Northern hybridization and immunohistochemistry, in ovarian endometriotic tissues removed during surgical procedures. We detected comparable expression of IGF-1 and IGF-1 receptor in the stromal and epithelial compartments, thus confirming disregulated expression of the IGF system in ovarian endometriosis. On the contrary, strongly increased TGF-beta 1 steady state level mRNA expression was detected in all endometriotic samples. In addition, we demonstrated weak TGF-beta 1 immunohistochemical expression in the epithelial lining and intense expression in the cellular stroma of ovarian endometriomas, thus suggesting that TGF-beta 1 could have an important role in the maintenance and propagation of the disease. On the basis of these preliminary results we can assume that TGF-beta 1, IGF-1 and their receptors may play an important role in the pathogenesis of endometriosis.
Abstract: BACKGROUND AND OBJECTIVE: To gain some insight into the photostimulation of isolated hepatocytes irradiated with Helium-Neon (He-Ne) laser light certain biochemical events were studied with respect to two mechanisms: i) the direct light dependent activation of certain biochemical events investigated in intact cells and isolated mitochondria, ii) the indirect stimulation of processes per se light independent. STUDY DESIGNS/MATERIALS AND METHODS: Irradiation of either isolated hepatocytes or isolated rat liver mitochondria was carried out with He-Ne laser (wavelength, 632.8 nm; fluence, 0.24 J cm-2; fluence rate, 12 mW cm-2). Changes in mitochondrial membrane potential in isolated hepatocytes were monitored using the cationic probe safranine. The c-fos expression was studied by Northern blot and immunoblot analysis. RESULTS: As a result of irradiation, increase of the mitochondrial membrane potential was found to occur in irradiated hepatocytes both in the presence or in the absence of CaCl2. The hyperpolarization of the mitochondrial membrane is assumed to cause an increase in mitochondrial Ca2+ uptake that was measured in isolated mitochondria. Finally, an increase in c-fos expression was found in irradiated hepatocytes when incubated in the presence of CaCl2. CONCLUSION: This paper gives additional information on the mechanism by which He-Ne laser light, either directly or in a cascade-like effect dependent on increase in cell Ca2+, can cause cell stimulation.
Abstract: Transforming growth factor-beta (TGF-beta) exerts an inhibitory effect on epithelial cell proliferation while insulin-like growth factor-1 (IGF-1) is a positive regulator of proliferation and together they may participate in driving neoplastic progression. The regulation of TGF-beta1 and IGF-1 gene expression was analyzed in an in vitro model of an estrogen receptor positive (ER+), non-metastatic (MCF-7) and an (ER-), metastatic (MDA-MB-435) breast cancer cell line, respectively. Our results indicate a loss of the regulation of TGF-beta1 and the gain of the expression and upregulation of IGF-1 pathways during malignant progression. These data demonstrate that two factors, convergent on cell growth, can have divergent roles in the regulation of the expression of TGF-beta1.
Abstract: Insulin-like growth factor 1 (IGF-1) likely is involved in thyrocyte proliferation via autocrine mechanisms, but limited data are available on its in vivo expression in thyroid neoplasms. This prompted us to explore IGF-1 expression at the protein and mRNA levels and IGF-1 receptor (IGF-1rec) immunoreactivity in normal and neoplastic thyroids (50 adenomas and 53 carcinomas). We documented increased IGF-1 and IGF-1rec immunoreactivity in adenomas (31 of 50 and 40 of 50 cases, respectively) and carcinomas (38 of 53 and 42 of 53 cases) compared with normal thyroid, which only showed minimal immunoreactivity for the ligand and its receptor. A corresponding up-regulation of IGF-1 mRNA was documented in carcinomas, whereas adenomas exhibited down-regulated expression of IGF-1 mRNA. Immunoreactivity for IGF-1 and cognate receptor positively correlated with tumor diameter and wide intrathyroidal extension but not with patients' gender and age or with the stage of the tumors and the occurrence of lymph node metastases. These data emphasize a possible role of the IGF-1 system in thyroid tumorigenesis, as indicated by in vitro studies. In addition, the evaluation of IGF-1 and IGF-1rec immunoreactivity might have clinical implications, because it positively correlates with the aggressiveness of these tumors.
Abstract: Alterations of integrin expression levels in cancer cells correlate with changes in invasiveness, tumor progression, and metastatic potential. The beta1C integrin, an alternatively spliced form of the human beta1 integrin, has been shown to inhibit prostate cell proliferation. Furthermore, beta1C protein levels were found to be abundant in normal prostate glandular epithelium and down-regulated in prostatic adenocarcinoma. To gain further insights into the molecular mechanisms underlying abnormal cancer cell proliferation, we have studied beta1C and beta1 integrin expression at both mRNA and protein levels by Northern and immunoblotting analysis using freshly isolated neoplastic and normal human prostate tissue specimens. Steady-state mRNA levels were evaluated in 38 specimens: 33 prostatic adenocarcinomas exhibiting different Gleason's grade and five normal tissue specimens that did not show any histological manifestation of benign prostatic hypertrophy. Our results demonstrate that beta1C mRNA is expressed in normal prostate and is significantly down-regulated in neoplastic prostate specimens. In addition, using a probe that hybridizes with all beta1 variants, mRNA levels of beta1 are found reduced in neoplastic versus normal prostate tissues. We demonstrate that beta1C mRNA down-regulation does not correlate with either tumor grade or differentiation according to Gleason's grade and TNM system evaluation, and that beta1C mRNA levels are not affected by hormonal therapy. In parallel, beta1C protein levels were analyzed. As expected, beta1C is found to be expressed in normal prostate and dramatically reduced in neoplastic prostate tissues; in contrast, using an antibody to beta1 that recognizes all beta1 variants, the levels of beta1 are comparable in normal and neoplastic prostate, thus indicating a selective down-regulation of the beta1C protein in prostate carcinoma. These results demonstrate for the first time that beta1C and beta1 mRNA expression is down-regulated in prostate carcinoma, whereas only beta1C protein levels are reduced. Our data highlight a selective pressure to reduce the expression levels of beta1C, a very efficient inhibitor of cell proliferation, in prostate malignant transformation.
Abstract: While the role of steroid hormones in the regulation of endometrial proliferation and differentiation is well established, the effects of growth factors and their receptors in normal and neoplastic endometrium remain a matter of debate. Previous studies have documented the positive effects of insulin-like growth factor-I (IGF-I) on epithelial cell proliferation and the active production of this growth factor in endometrial tissues. In view of decreased expression of transforming growth factor-beta1 (TGF-beta1), an antagonist of IGF-I, in endometrial carcinoma, we investigated the expression of IGF-I, at both the mRNA and protein levels, and the immunoreactivity for type I IGF-I receptor in 30 formalin-fixed, paraffin-embedded tissue samples of normal and neoplastic endometrium, in order to possibly clarify the role of IGF-I in endometrial proliferation and differentiation. Our results demonstrate a reduced expression of IGF-I mRNA in endometrial carcinomas compared with non-neoplastic tissues, despite equivalent immunohistochemical expression of IGF-I and IGF-I receptor. Our data suggest that IGF-I and its corresponding receptor may not be directly involved in endometrial cancer cell proliferation and differentiation in vivo, though other components of the IGF-I system (e.g., IGF binding proteins) may affect endometrial malignant transformation and tumor progression.
Abstract: OBJECTIVES: Endometrial cells may synthetize cytokines and growth factors which may modulate some of the molecular mechanisms of endometrial proliferation and differentiation. PATIENTS AND METHODS: We investigated the role of transforming growth factor beta-1 (TGF-beta 1), insulin-like growth factor-1 (IGF-1) and relative receptors in five tissue samples from atrophic post-menopausal endometria. The control group was represented by proliferative and secretory endometria from 10 healthy, normally-menstratued women. TGF-beta 1 and IGF-1 m-RNA expression was evaluated by Northern hybridization analysis, while TGF-beta 1 and IGF-1 receptors distribution was studied by immunohistochemistry. RESULTS: In atrophic endometria Northern hybridization analysis showed a significant decrease of IGF-1 expression, and an increase of TGF-beta 1 expression compared to proliferative and secretory endometria. By immunohistochemistry it was demonstrated that TGF-beta 1 and IGF-1 receptors were both localized in cell cytoplasm, mainly in the stromal compartment. CONCLUSIONS: The results of our study would suggest a possible role of IGF-1 and TGF-beta 1 in maintaining the quiescent differentiative state of atrophic post-menopausal endometrium. The persistence of IGF-1 and TGF-beta 1 receptors in epithelial compartment could play a key role in proliferative response of atrophic endometrium to exogenous hormone replacement therapy (HRT) or endogenous intervening high estrogens levels.
Abstract: The present study describes two Na+/H+ exchanger (NHE) isoforms in an immortalized rabbit renal cortical collecting tubule cell line (RC.SV3). Na+/H+ exchange activity was assayed using fluorescence measurements of intracellular pH (pHi) in monolayers mounted in a cuvette containing two fluid compartments, making it possible to independently measure Na+/H+ exchange activity on either the apical or basolateral surface. RC.SV3 monolayers express Na+/H+ exchange activities in both the apical and basolateral membrane domains. The two exchangers have half-saturation constants (Km) for external sodium and sensitivities to dimethylamiloride, to HOE-694 and to cimetidine and clonidine consistant with the NHE-1 isoform on the basolateral cell surface and the NHE-2 isoform on the apical surface. Protein kinase A inhibition of basolateral exchanger activity was significantly higher than that of the apical exchanger. Protein kinase C significantly stimulated both exchangers equally. RT-PCR analysis found RNA for only NHE-1 and NHE-2, and immunofluorescence with an antibody against NHE-1 demonstrated a basolateral location for this isoform. The results suggest that RC.SV3 cells have two Na+/H+ exchange activities separated spatially to the two cellular membranes, with the NHE-1 and the NHE-2 isoforms located on the basolateral and the apical membranes, respectively.
Abstract: Transforming growth factor beta1 (TGF-beta1) is a potent modulator of cell proliferation in vitro, and recent studies have demonstrated its overexpression in several different tumours; nevertheless, the molecular mechanisms of TGF-beta1 action on cell growth and differentiation have not been fully elucidated. To clarify the role of TGF-beta and its receptor in human endometrial proliferation and differentiation, TGF-beta1 expression at both the mRNA and protein levels has been evaluated by using Northern blotting and immunohistochemistry, in both normal (atrophic, proliferative and secretory) and neoplastic (adenocarcinoma) endometrial samples. This study demonstrates that TGF-beta1 mRNA expression is dramatically reduced in endometrial carcinomas with respect to non-neoplastic tissues, whereas the immunohistochemical expression of TGF-beta1 is enhanced in the epithelial component of endometrial carcinomas compared with non-neoplastic tissues. These data suggest that TGF-beta1 acts as a paracrine regulator of endometrial cell proliferation and that it may contribute to the carcinogenic mechanisms of endometrial carcinoma.
Abstract: Hemangioma of the ovary is extremely rare. We report the case of a 32-year-old woman who complained of pelvic pain due to a large right adnexal mass. On surgical exploration a 10 x 8 cm hemangioma of the ovary was resected. Expression of transforming growth factor-beta1 was studied, and the possible role of this molecule in the development of the tumor is discussed.
Abstract: Growth factors are frequently involved in the regulation of mitosis and differentiation of several cell types and insulin-like growth factor-1 (IGF-1) is actively involved in the thyroid stimulating hormone-mediated proliferation of thyrocytes. In view of the pivotal role of IGF-1 in thyrocyte proliferation and of the still unsettled role of this growth factor in the pathogenesis of hyperplastic thyroid lesions, we investigated the expression of IGF-1 and of its corresponding receptor, by means of immunohistochemistry, in the surgical specimens obtained from six patients with Graves' disease. Moreover, IGF-1 mRNA expression was analysed in one such case by means of Northern hybridisation. All samples showed consistent intracytoplasmic immunoreactivity for both IGF-1 and IGF-1 receptor; the vast majority of hyperplastic thyrocytes were strongly decorated by the two antibodies used in this study whereas stromal cells displayed IGF-1 immunoreactivity only. IGF-1 mRNA was markedly overexpressed in Graves' disease in comparison with normal thyroid tissues. The results of this study suggest that IGF-1 and IGF-1 receptor may be actively involved in the pathogenesis of Graves' disease; furthermore, IGF-1 and IGF-1 receptor apparently act by different mechanisms (paracrine vs. autocrine) as suggested by their differential expression in epithelial and stromal cells.
Abstract: Little is known about control of expression of basal levels of the aspartate aminotransferases which are ubiquitous 'house keeping' enzymes in vertebrates. We have measured both mRNA and activity levels for both isoenzymes in various rat tissues as a function of age. Patterns of mRNA expression for the two isoenzymes were similar in a particular tissue about differed widely between tissues. Surprisingly, there was no simple correlation between mRNA levels and specific activities of the enzyme products. We conclude that translation for mRNA for these two isoenzymes is subject to tissue-specific, and in some cases age-related, regulation.
Abstract: To find a clinical assay for histiocytosis X (HX) diagnosis, measurements were made of both activity and isoenzyme distribution of lactate dehydrogenase (LDH; EC 1.1.1.27) from the blood cells of 6 acute phase and 9 remission patients. A significant increase in the LDH activity measured in the monocytes and lymphocytes isolated from the blood of the acute phase patients was found. The increased activity was due to an enhancement of the normal pattern of LDH isoenzymes in these cells and not to a change in isoenzyme distribution. No increase was found in monocyte LDH isoenzymes from the patients in remission.
Abstract: An experiment was performed to isolate the small atypical mitochondria produced during the irradiation of normal mitochondria with an He-Ne laser. Rat liver mitochondria were irradiated with a low-power continuous-wave He-Ne laser (energy dose, 5 J cm-2), followed by isolation using a sucrose gradient. In the irradiated sample, two bands were observed, one corresponding to normal mitochondria and the other to atypical mitochondria. Certain biochemical features of the mitochondria were investigated: mitochondrial enzyme activity and the presence of DNA and RNA were demonstrated. Hybridization experiments carried out with labelled mitochondrial probes, containing the genes for cytochrome oxidase subunit I and 12S rRNA, confirmed the mitochondrial nature of the isolated RNA.
Abstract: To gain further insight into the mechanism of cell photostimulation by laser light, both RNA and protein synthesis were measured in mitochondria irradiated with the low power continuous wave He-Ne laser (Energy dose: 5 Joules/cm2). Following mitochondrial irradiation, both the rate and amount of incorporation of alpha-[32P]UTP and L-[35S]methionine, used to monitor RNA and protein synthesis respectively, proved to increase. Electrophoretic analysis made of the synthesis products clearly shows that He-Ne laser irradiation stimulates the synthesis of all mitochondrial transcription and translation products.
