Bcl-2 family members and disease

Anti-apoptosis and cell survival: a review

Type I programmed cell death (PCD) or apoptosis is critical for cellular self-destruction for a variety of processes such as development or the prevention of oncogenic transformation. Alternative forms, including type II (autophagy) and type III (necrotic) represent the other major types of PCD that also serve to trigger cell death. PCD must be tightly controlled since disregulated cell death is involved in the development of a large number of different pathologies. To counter the multitude of processes that are capable of triggering death, cells have devised a large number of cellular processes that serve to prevent inappropriate or premature PCD. These cell survival strategies involve a myriad of coordinated and systematic physiological and genetic changes that serve to ward off death. Here we will discuss the different strategies that are used to prevent cell death and focus on illustrating that although anti-apoptosis and cellular survival serve to counteract PCD, they are nevertheless mechanistically distinct from the processes that regulate cell death.

Mcl-1; the molecular regulation of protein function

Apoptosis, an essential and basic biological phenomenon, is regulated in a complex manner by a multitude of factors. Myeloid cell leukemia 1 (Mcl-1), an anti-apoptotic member of the B-cell lymphoma 2 (Bcl-2) family of apoptosis-regulating proteins, exemplifies a number of the mechanisms by which a protein's contribution to cell fate may be modified. The N-terminus of Mcl-1 is unique amongst the Bcl-2 family, in that it is rich in experimentally confirmed and putative regulatory residues and motifs. These include sites for ubiquitination, cleavage and phosphorylation, which influence the protein's stability, localisation, dimerization and function. Here we review what is known about the regulation of Mcl-1 expression and function, with particular focus on post-translational modifications and how phosphorylation interconnects the complex molecular control of Mcl-1 with cellular state.

The biological properties of E6 and E7 oncoproteins from human papillomaviruses

More than 100 different human papillomavirus (HPV) types have been isolated so far, and they can be sub-grouped in cutaneous or mucosal according to their ability to infect the skin or the mucosa of the genital or upper-respiratory tracts. A sub-group of human mucosal HPVs, referred to as high-risk HPV types, is responsible for approximately 5% of all human cancers, which represents one-third of all the tumours induced by viruses. Epidemiological and biological studies have shown that HPV16 is the most oncogenic type within the high-risk group. Emerging lines of evidence suggest that, in addition to the high-risk mucosal HPV types, certain cutaneous HPVs are involved in skin cancer. HPV-associated cancers are intimately linked to HPV persistence and the accumulation of chromosomal rearrangements. The products of the early genes, E6 and E7, of the high-risk mucosal HPV types play a key role in both events. Indeed, these proteins have developed a number of strategies to evade host immuno-surveillance allowing viral persistence, and to alter cell cycle and apoptosis control, facilitating the accumulation of DNA damage/mutations. Often, the two oncoproteins target the same cellular pathways with different mechanisms, showing a strong synergism in promoting cellular transformation and neutralizing the immune response. Here, we review most of the findings on the biological properties and molecular mechanisms of the oncoproteins E6 and E7 from mucosal and cutaneous HPV types.

Heat shock protein 60, via MyD88 innate signaling, protects B cells from apoptosis, spontaneous and induced

We recently reported that heat shock protein 60 (HSP60) via TLR4 signaling activates B cells and induces them to proliferate and secrete IL-10. We now report that HSP60 inhibits mouse B cell apoptosis, spontaneous or induced by dexamethasone or anti-IgM activation. Unlike HSP60 enhancement of B cell proliferation and IL-10 secretion, TLR4 signaling was not required for the inhibition of apoptosis by HSP60; nevertheless, MyD88 was essential. Inhibition of apoptosis by HSP60 was associated with up-regulation of the antiapoptotic molecules Bcl-2, Bcl-x(L), and survivin, maintenance of the mitochondrial transmembrane potential, and inhibition of caspase-3 activation. Moreover, B cells incubated with HSP60 manifested prolonged survival following transfer into recipient mice. These results extend the varied role of HSP60 in the innate regulation of the adaptive immune response.

Heterotrimeric G proteins and apoptosis: intersecting signaling pathways leading to context dependent phenotypes

Apoptosis, a programmed cell death mechanism, is a fundamental process during the normal development and somatic maintenance of all multicellular organisms and thus is highly conserved and tightly regulated through numerous signaling pathways. Apoptosis is of particular clinical importance as its dysregulation contributes significantly to numerous human diseases, primarily through changes in the expression and activation of key apoptotic regulators. Each of the four families of heterotrimeric G proteins (G(s), G(i/o), G(q/11) and G(12/13)) has been implicated in numerous cellular signaling processes, including proliferation, transformation, migration, differentiation, and apoptosis. Heterotrimeric G protein signaling is an important but not widely studied mechanism regulating apoptosis. G protein Signaling and Apoptosis broadly cover two large bodies of literature and share numerous signaling pathways. Examination of the intersection between these two areas is the focus of this review. Several studies have implicated signaling through each of the four heterotrimeric G protein families to regulate apoptosis within numerous disease contexts, but the mechanism(s) are not well defined. Each G protein family has been shown to stimulate and/or inhibit apoptosis in a context-dependent fashion through regulating numerous downstream effectors including the Bcl-2 family, NF-kappaB, PI3 Kinase, MAP Kinases, and small GTPases. These cell-type specific and G protein coupled receptor dependent effects have led to a complex body of literature of G protein regulation of apoptosis. Here, we review the literature and summarize apoptotic signaling through each of the four heterotrimeric G protein families (and the relevant G protein coupled receptors), and discuss limitations and future directions for research on regulating apoptosis through G protein coupled mechanisms. Continued investigation in this field is essential for the identification of important targets for pharmacological intervention in numerous diseases.

Peptides and peptide mimics as modulators of apoptotic pathways

Programmed cell death is an important and stringently controlled process. Aberrancies in its control mechanisms can lead to disease; overactive apoptosis can cause neurodegenerative disorders, whereas deficient apoptotic activity can lead to cancer. Therefore, controlling apoptotic pathways with peptides is showing increasing promise as a strategy in drug development.Programmed cell death or apoptosis is a noninvasive and strictly regulated cellular process required for organism development and tissue homeostasis. Deficiencies in apoptotic pathways are the source of many diseases such as cancer, neurodegenerative and autoimmune diseases, and disorders related to an inappropriate loss of cells such as heart failure, stroke, and liver injury. Validation of the various points of intervention as targets for drug development has been the subject of a vast number of studies. Peptides are essential tools for drug discovery, as well as preclinical and pharmaceutical drug development.

Determination of nitric oxide synthase activity and apoptosis of germ cells in different obstruction models

We aimed to determine the changes of inducible nitric oxide synthase (iNOS) and endothelial nitric oxide synthase (eNOS) immunoreactivity and apoptosis after proximal and distal obstruction models on ipsilateral and contralateral testicular tissues. Male albino Wistar rats were randomly divided into three groups (n=30): a control group which underwent sham operations (n=10), a unilateral vasal ligation (n=10) and a unilateral epididymal ligation group (n=10). iNOS and eNOS distribution and apoptosis were studied in both ipsilateral and contralateral testes using quantitative immunohistochemistry. Nitric oxide synthase activity was significantly affected in ipsilateral and contralateral testes cells after vasal and epididymal ligation. eNOS immunoreactivity increased markedly after ipsilateral vasal ligation (ILVL). Degeneration-related changes were also associated with changes in apoptotic rate. Analysis using the terminal dUTP nick end-labeling TUNEL method revealed that apoptotic cell numbers significantly increased after ILVL. p53 and bcl-2 immunoreactivity increased in both experimental groups compared with the sham-operated group. Changes in iNOS and eNOS immunolocalisation were strongly associated with cell damage, because germ cell degeneration was more prominent in the ILVL group. Altered p53 immunolocalisation was also associated with cell degeneration, and a rise in bcl-2 immunoreactivity might be considered to reflect a protective mechanism in the testis. These cellular changes could enlighten understanding of the interaction between testicular functioning and damage.

Endothelin A receptor blockade influences apoptosis and cellular proliferation in the developing rat kidney

Endothelin systems are believed to play important roles in the emergence and maintenance of functions of various organs during perinatal development, including the kidney. The present study was designed to investigate the roles of endothelin systems on physiologic renal growth and development. Newborn rat pups were treated with either Bristol-Myers Squibb-182874 (30 mg/kg/day), a selective endothelin A receptor (ET(A)R) antagonist, or vehicle for 7 days. To identify cellular changes, kidneys were examined for apoptotic cells by terminal deoxynucleotide transferase-mediated nick-end labeling stain and proliferating cell nuclear antigen (PCNA) by immunohistochemical (IHC) stain. To clarify the molecular control of these processes, immunoblots and reverse transcriptase-polymerase chain reaction for Clusterin, Bcl-2, Bcl-X(L), Bax, and p53 were performed. ETAR antagonist treatment resulted in reduced kidney weights, decreased PCNA-positive proliferating cells, and increased apoptotic cells. The protein expressions of renal Bcl-X(L) and Bax in the ETAR antagonist-treated group were significantly decreased, whereas the mRNA expressions of these genes were not changed. There were no significant differences in the expressions of Clusterin, Bcl-2, and p53. In conclusion, inhibition of endogenous endothelins impairs renal growth, in which decreased cellular proliferation, increased apoptosis and decreased expressions of renal Bcl-X(L) and Bax are possibly implicated.

Assessment of expression of selected Bcl-2 family proteins in lymphoid infiltration in patients with B-cell chronic lymphocytic leukaemia treated with nucleoside analogues

B-cell chronic lymphocytic leukaemia (B-CLL) is characterized by clonal growth and accumulation of mature lymphoid cells due to disturbance in genetically regulated form of cell death called apoptosis. The intrinsic mechanism of apoptosis is controlled by Bcl-2 family proteins. Purine nucleoside analogues induce the apoptosis in cells in a state of quiescence. The aim of the study was to assess expression of selected Bcl-2 family proteins in neoplastic infiltration in bone marrow in patients with B-CLL treated with nucleoside analogues. The study comprised examination of bone marrow obtained routinely by trephine biopsy from 18 patients with B-CLL diagnosed before administration of purine nucleoside analogues treatment and after its completion. Expression of Bcl-2, Bcl-x and Bax proteins was examined. Lymphoid cells in bone marrow were present in all patients before administration of treatment. After treatment in two patients bone marrow was infiltrated in diffuse pattern, whereas other patients presented nodular pattern of infiltration. The difference between stage of infiltration before and after treatment was statistically significant (p<0.002). High percentage of infiltration cells with positive anti Bcl-2 reaction from 42.0% in one patient to 85.33+/-3.06% in four patients before treatment was observed. After treatment percentage of infiltration cells with positive anti Bcl-2 antibody reaction was from 33.0+/-18.38% in two patients to 99.0% in one patient. Positive correlation between stage of infiltration and expression of Bcl-2 protein was confirmed before and after treatment. Such correlations were not observed in case of Bax and Bcl-x. Strong staining of immunohistochemical reaction of cells in lymphoid infiltration with Bcl-2 antibody was confirmed. There was a difference between Bcl-/Bax ratio before and after treatment. Immunohistochemical assessment of expression of Bcl-2 family proteins in cells of lymphoid infiltration in bone marrow of patients with CLL is an important method in detection of minimal residual disease (MRD) after treatment.

Anti-apoptotic Bcl-XL protein in complex with BH3 peptides of pro-apoptotic Bak, Bad, and Bim proteins: comparative molecular dynamics simulations

The Bcl-2 family of proteins plays a central role in the regulation of mitochondrial outer-membrane permeabilization, a critical step in apoptosis. Heterodimerization between the pro- and anti-apoptotic members of Bcl-2 family is a key event in this process. Anti-apoptotic proteins have high levels of expression in many cancers and they have different affinities for different pro-apoptotic proteins. Experimentally determined structures of all members of Bcl-2 proteins have remarkably similar helical fold despite poor amino acid sequence identity. Peptides representing BH3 region of pro-apoptotic proteins have been shown to bind the hydrophobic cleft of anti-apoptotic proteins and this segment is responsible in modulating the apoptotic pathways in living cells. Understanding the molecular basis of protein-protein recognition is required to develop inhibitors specific to a particular anti-apoptotic protein. We have carried out molecular dynamics simulations on the anti-apoptotic Bcl-X(L) protein in complex with three different BH3 peptides derived from pro-apoptotic Bak, Bad and Bim proteins. Each complex structure was simulated for a period of 50 ns after 2.5 ns equilibration. Analysis of the simulation results showed that in the Bcl-X(L) protein, the helix containing the BH3 region is more flexible than other helices in all three simulations. A network of strong hydrophobic interactions exists between four of the six helices and they contribute significantly to the stability of this helix bundle protein. Analysis of Bcl-X(L)-BH3 peptide interactions reveals the role of loop residues in the protein-peptide interactions in all three simulations. Bad and Bim peptides maintain strong hydrophobic and hydrophilic interactions with the helix preceding the central hydrophobic helix. Residues from this helix interact with an Arg residue in Bad and Bim peptides. This Arg residue is next to the conserved Leu residue and is replaced by Ala in Bak. Absence of these interactions and the helix propensity are likely to be the cause for Bak peptide's weaker binding affinity with the Bcl-X(L) protein. The results of this study have implications in the design of Bcl-X(L)-specific inhibitors.

Live and let die - regulation of villous trophoblast apoptosis in normal and abnormal pregnancies

Since 1995 the number of publications investigating apoptosis in villous trophoblast has increased exponentially. This scientific interest is in part due to observations that this specialised form of cell death is increased in pregnancy complications such as pre-eclampsia and intra-uterine growth restriction. In addition, apoptosis is described in normal villous trophoblast and elements of the apoptotic machinery are involved in the fusion between cytotrophoblast and the overlying multinucleate syncytiotrophoblast. The increase in descriptions of apoptotic cell death in villous trophoblast has been accompanied by investigations of regulators of apoptosis. It is anticipated that understanding the regulation of apoptosis in villous trophoblast may provide new insights into placental pathologies. This review describes current knowledge regarding the expression and function of these regulators in villous trophoblast, both in normal and complicated pregnancies.

Targeting the apoptotic pathway with BCL-2 inhibitors sensitizes primary chronic lymphocytic leukemia cells to vesicular stomatitis virus-induced oncolysis

Chronic lymphocytic leukemia (CLL) is characterized by clonal accumulation of CD5(+) CD19(+) B lymphocytes that are arrested in the G(0)/G(1) phase of the cell cycle and fail to undergo apoptosis because of overexpression of the antiapoptotic B-cell CLL/lymphoma 2 (BCL-2) protein. Oncolytic viruses, such as vesicular stomatitis virus (VSV), have emerged as potential anticancer agents that selectively target and kill malignant cells via the intrinsic mitochondrial pathway. Although primary CLL cells are largely resistant to VSV oncolysis, we postulated that targeting the apoptotic pathway via inhibition of BCL-2 may sensitize CLL cells to VSV oncolysis. In the present study, we examined the capacity of EM20-25--a small-molecule antagonist of the BCL-2 protein--to overcome CLL resistance to VSV oncolysis. We demonstrate a synergistic effect of the two agents in primary ex vivo CLL cells (combination index of 0.5; P < 0.0001). In a direct comparison of peripheral blood mononuclear cells from healthy volunteers with primary CLL, the two agents combined showed a therapeutic index of 19-fold; furthermore, the combination of VSV and EM20-25 increased apoptotic cell death in Karpas-422 and Granta-519 B-lymphoma cell lines (P < 0.005) via the intrinsic mitochondrial pathway. Mechanistically, EM20-25 blocked the ability of the BCL-2 protein to dimerize with proapoptotic BAX protein, thus sensitizing CLL to VSV oncolytic stress. Together, these data indicate that the use of BCL-2 inhibitors may improve VSV oncolysis in treatment-resistant hematological malignancies, such as CLL, with characterized defects in the apoptotic response.

Attenuation of retinal endothelial cell migration and capillary morphogenesis in the absence of bcl-2

Apoptosis plays a critical role during development and in the maintenance of the vascular system. B-cell leukemia lymphoma 2 (bcl-2) protects endothelial cells (EC) from apoptosis in response to a variety of stimuli. Previous work from this laboratory demonstrated attenuation of postnatal retinal vascular development and retinal neovascularization during oxygen-induced ischemic retinopathy in bcl-2-deficient (bcl-2-/-) mice. To gain further insight into the function of bcl-2 in the endothelium, we isolated retinal EC from bcl-2+/+ and bcl-2-/- mice. Retinal EC lacking bcl-2 demonstrated reduced cell migration, tenascin-C expression, and adhesion to vitronectin and fibronectin. The bcl-2-/- retinal EC also failed to undergo capillary morphogenesis in Matrigel. In addition, using an ex vivo angiogenesis assay, we observed reduced sprouting from aortic rings grown in culture from bcl-2-/- mice compared with bcl-2+/+ mice. Furthermore, reexpression of bcl-2 was sufficient to restore migration and capillary morphogenesis defects observed in bcl-2-/- retinal EC. Mechanistically, bcl-2-/- cells expressed significantly less endothelial nitric oxide synthase, an important downstream effecter of proangiogenic signaling. This may be attributed to increased oxidative stress in the absence of bcl-2. In fact, incubation of retinal EC or aortic rings from bcl-2-/- mice with the antioxidant N-acetylcysteine rescued their capillary morphogenesis and sprouting defects. Thus, bcl-2-mediated cellular functions play important roles not only in survival but also in proangiogenic phenotype of EC with a significant impact on vascular development and angiogenesis.

Modulation of granulocyte apoptosis can influence the resolution of inflammation

Apoptosis of granulocytes and the subsequent clearance of apoptotic cells are important processes for the successful resolution of inflammation. Signalling pathways, including those involving NF-kappaB (nuclear factor kappaB), MAPK (mitogen-activated protein kinase) and PI3K (phosphoinositide 3-kinase) have been shown to be key regulators of inflammatory cell survival and apoptosis in vitro. In addition, manipulation of such pathways in vivo has indicated that they also play a role in the resolution of inflammation. Furthermore, manipulation of proteins directly involved in the control of apoptosis, such as Bcl-2 family members and caspases, can be targeted in vivo to influence inflammatory resolution. Recently, it has been shown that CDK (cyclin-dependent kinase) inhibitor drugs induce caspase-dependent human neutrophil apoptosis possibly by altering levels of the anti-apoptotic Bcl-2 family member, Mcl-1. Importantly, CDK inhibitor drugs augment the resolution of established 'neutrophil-dominant' inflammation by promoting apoptosis of neutrophils. Thus manipulation of apoptotic pathways, together with ensuring macrophage clearance of apoptotic cells, appears to be a viable pharmacological target for reducing established inflammation.

Importance of cytokines, oxidative stress and expression of BCL-2 in the pathogenesis of non-alcoholic steatohepatitis

OBJECTIVE

Non-alcoholic steatohepatitis (NASH) is a form of chronic hepatitis. The pathogenesis of NASH has been dealt with in only a few studies and so it has not been clearly identified yet. The purpose of this study was to investigate the roles of TNF-alpha, TGF-beta, IL-6, IL-8, malondialdehyde (MDA), nitric oxide (NO) and the expression of Bcl-2 and Bax in the pathogenesis of NASH.

MATERIAL AND METHODS

The study included 92 patients, 57 of whom were diagnosed with biopsy-proven NASH, 13 with biopsy-proven hepatosteatosis and 22 with ultrasonography-diagnosed hepatosteatosis. Serum levels of TNF-alpha, TGF-beta, IL-6 and IL-8 were measured using the ELISA method. The plasma levels of NO were studied using the Griess method. Expressions of Bcl-2 and Bax were examined in paraffin blocks of liver biopsy materials by means of immunohistochemical-staining. MDA levels were measured using the thiobarbituric acid method.

RESULTS

No significant difference was found in the levels of TNF-alpha, TGF-beta, IL-6 or NO between the three groups (p>0.05). No difference was found in expression of Bcl-2 and expression of Bax between the biopsy-proven NASH and biopsy-proven hepatosteatosis groups (p>0.05). In the NASH group, the levels of IL-8 and MDA were found to be higher than those in the hepatosteatosis groups (p<0.05).

CONCLUSIONS

The elevated levels of MDA may indicate the relationship between oxidative stress and NASH. Furthermore, IL-8 was found to be higher in the NASH group than in the hepatosteatosis group, demonstrating the importance of inflammation in the pathogenesis of NASH.

Gene Expression Profiling of Rewarding Effect in Methamphetamine Treated Bax-deficient Mouse

Methamphetamine is an illicit drug that is often abused and can cause neuropsychiatric and neurotoxic damage. Repeated administration of psychostimulants such as methamphetamine induces a behavioral sensitization. According to a previous study, Bax was involved in neurotoxicity by methamphetamine, but the function of Bax in rewarding effect has not yet been elucidated. Therefore, we have studied the function of Bax in a rewarding effect model. In the present study, we treated chronic methamphetamine exposure in a Bax-deficient mouse model and examined behavioral change using a conditioned place preference (CPP) test. The CPP score in Bax knockout mice was decreased compared to that of wild-type mice. Therefore, we screened for Bax-related genes that are involved in rewarding effect using microarray technology. In order to confirm microarray data, we applied the RT-PCR method to observe relative changes of Bcl2, a pro-apoptotic family gene. As a result, using our experiment microarray, we selected genes that were associated with Bax in microarray data, and eventually selected the Tgfbr2 gene. Expression of the Tgfbr2 gene was decreased by methamphetamine in Bax knockout mice, and the gene was overexpressed in Bax wild-type mice. Additionally, we confirmed that Creb, FosB, and c-Fos were related to rewarding effect and Bax using immunohistochemistry.

Differential nigral expression of bcl-2 protein family in the pure and common forms of Dementia with Lewy bodies: relevance for dopaminergic neuronal vulnerability

We investigated whether bcl-2 protein family is involved in the pathogenesis of the dopaminergic neurodegeneration that occurs in Dementia with Lewy bodies (DLB). The expression of the proapoptotic protein bax and the antiapoptotic proteins bcl-2 and bcl-xL was investigated by Western blot in the pars compacta of the substantia nigra of pure and common DLB forms. No changes in the nigral expression levels of bax, bcl-2 and bcl-xL proteins were found between control and DLB pure cases. In the common DLB forms, nigral bcl-xL and bcl-2 proteins levels were significantly decreased in the DLB cases associated with a concomitant severe AD pathology (p < 0.05). An increase in nigral bcl-2 protein expression was observed in the DLB cases with a mild AD-associated pathology (p < 0.05). The present results are in agreement with previous observations indicating that DLB cases with severe AD pathology tend to show severe Lewy pathology suggesting that AD pathology might exacerbate Lewy pathology.

Function of nuclear steroid receptors in apoptosis: role of ursodeoxycholic acid

Nuclear steroid receptors such as the glucocorticoid and the mineralocorticoid receptors modulate apoptosis in different cell types through transactivation-dependent and -independent mechanisms. They are involved in both the induction and prevention of apoptosis depending on cell type. However, it is unclear how nuclear steroid receptors can affect expression of the same gene in opposing ways for different cells. In addition to their function as modulators of gene expression, nuclear steroid receptors often act as nuclear transporters of other regulatory molecules, thus indirectly regulating several apoptosis-related genes. Curiously, nuclear steroid receptors are thought to cooperate with the antiapoptotic endogenous bile acid, ursodeoxycholic acid, to prevent programmed cell death. The next decade will almost certainly unveil the remarkable role of nuclear steroid receptors in modulating the life and death struggle of cells and organ systems in human development and function.

Galpha12 stimulates apoptosis in epithelial cells through JNK1-mediated Bcl-2 degradation and up-regulation of IkappaBalpha

Apoptosis is an essential mechanism for the maintenance of somatic tissues, and when dysregulated can lead to numerous pathological conditions. G proteins regulate apoptosis in addition to other cellular functions, but the roles of specific G proteins in apoptosis signaling are not well characterized. Galpha12 stimulates protein phosphatase 2A (PP2A), a serine/threonine phosphatase that modulates essential signaling pathways, including apoptosis. Herein, we examined whether Galpha12 regulates apoptosis in epithelial cells. Inducible expression of Galpha12 or constitutively active (QL)alpha12 in Madin-Darby canine kidney cells led to increased apoptosis with expression of QLalpha12, but not Galpha12. Inducing QLalpha12 led to degradation of the anti-apoptotic protein Bcl-2 (via the proteasome pathway), increased JNK activity, and up-regulated IkappaBalpha protein levels, a potent stimulator of apoptosis. Furthermore, the QLalpha12-stimulated activation of JNK was blocked by inhibiting PP2A. To characterize endogenous Galpha12 signaling pathways, non-transfected MDCK-II and HEK293 cells were stimulated with thrombin. Thrombin activated endogenous Galpha12 (confirmed by GST-tetratricopeptide repeat (TPR) pull-downs) and stimulated apoptosis in both cell types. The mechanisms of thrombin-stimulated apoptosis through endogenous Galpha12 were nearly identical to the mechanisms identified in QLalpha12-MDCK cells and included loss of Bcl-2, JNK activation, and up-regulation of IkappaBalpha. Knockdown of the PP2A catalytic subunit in HEK293 cells inhibited thrombin-stimulated apoptosis, prevented JNK activation, and blocked Bcl-2 degradation. In summary, Galpha12 has a major role in regulating epithelial cell apoptosis through PP2A and JNK activation leading to loss of Bcl-2 protein expression. Targeting these pathways in vivo may lead to new therapeutic strategies for a variety of disease processes.

Regulation of Bcl-xL expression in lung vascular smooth muscle

Pulmonary hypertension is characterized by thickened pulmonary arterial walls due to increased number of pulmonary artery smooth muscle cells (PASMC). Apoptosis of PASMC may play an important role in regulating the PASMC number and may be useful for reducing pulmonary vascular thickening. The present study examined the regulation of an anti-apoptotic protein Bcl-x(L). Bcl-x(L) expression was found to be increased in the pulmonary artery of chronic hypoxia-treated rats with pulmonary vascular remodeling. Adenovirus-mediated gene transfer of Bcl-x(L) indeed showed that this protein has anti-apoptotic activities in PASMC. Treatment of remodeled pulmonary artery with sodium nitroprusside (SNP) reduced Bcl-x(L) expression by targeting the bcl-x(L) promoter. The bcl-x(L) promoter contains two GATA elements, and SNP decreases the GATA-4 DNA-binding activity. Overexpression of GATA-4 attenuated the SNP-mediated suppression of Bcl-x(L) expression, providing direct evidence for the role of GATA-4 in Bcl-x(L) gene transcription. We established that SNP targets the 250 proximal region of the gata4 promoter and suppresses its gene transcription. Thus, inducers of pulmonary hypertension enhance anti-apoptotic Bcl-x(L) gene transcription, which can be suppressed by targeting gata4 gene transcription.

Characterizing regeneration in the vertebrate ear

We have previously shown that MRL/MpJ mice have a capacity for regeneration instead of scar formation following an ear punch wound. Understanding the differences that occur between scar-free regeneration or repair with scarring will have great impact upon advances in skin tissue engineering. A key question that remains unanswered in the MRL/MpJ mouse model is whether regeneration was restricted to the ear or whether it extended to the skin. A histological analysis was conducted up to 4 months post-wounding, not only with 2-mm punch wounds to the ear but also to the skin on the backs of the same animals. MRL/MpJ mouse ear wounds regenerate faster than control strains, with enhanced blastema formation, a markedly thickened tip epithelium and reduced scarring. Interestingly, in the excisional back wounds, none of these regenerative features was observed and both the C57BL/6 control and MRL/MpJ mice healed with scarring. This review gives an insight into how this regenerative capacity may be due to evolutionary processes as well as ear anatomy. The ear is thin and surrounded on both sides by epithelia, and the dorsal skin is devoid of cartilage and under greater tensile strain. Analysis of apoptosis during ear regeneration is also discussed, assessing the role and expression of various members of the Bcl-2 family of proteins. Ongoing studies are focusing on de novo cartilage development in the regenerating ear, as well as understanding the role of downstream signalling cascades in the process. Identification of such signals could lead to their manipulation and use in a novel tissue-engineered skin substitute with scar-free integration.

Development of selective inhibitors for anti-apoptotic Bcl-2 proteins from BHI-1

A series of inhibitors for anti-apoptotic Bcl-2 proteins based on BHI-1 were synthesized and their binding interactions with Bcl-2, Bcl-X(L), and Bcl-w were evaluated. It was found that modification of BHI-1 resulted in varied binding profiles among Bcl-2, Bcl-X(L), and Bcl-w, and a set of inhibitors with varied selectivity to Bcl-2, Bcl-X(L), and Bcl-w proteins have been identified. Molecular modeling of the interaction of the BHI-1 based analogues with the anti-apoptotic Bcl-2 proteins suggested that the binding site for the BHI-1 based inhibitor was the least conserved section among Bcl-2, Bcl-X(L), and Bcl-w: targeting the non-conserved section may account for the observed selectivity of the BHI-1 based inhibitors among the anti-apoptotic Bcl-2 proteins. The validity of the model was supported by a strong correlation between the model-calculated binding energy and the experimental binding affinity. In summary, our studies suggest that most of the reported inhibitors for anti-apoptotic Bcl-2 proteins are nonselective and BHI-1 is a promising template to distinguish among Bcl-2, Bcl-X(L), and Bcl-w by targeting the non-conserved domain among the anti-apoptotic Bcl-2 proteins. Molecular-modeling-aided rational development of BHI-1 based selective inhibitor for anti-apoptotic Bcl-2 proteins is underway.

Surviving cell death through epidermal growth factor (EGF) signal transduction pathways: Implications for cancer therapy

There is a balance between cell death and survival in living organisms. The ability of cells to sense their environment and decide to survive or die is dependent largely upon growth factors. Epidermal growth factor (EGF) is a key growth factor regulating cell survival. Through its binding to cell surface receptors, EGF activates an extensive network of signal transduction pathways that include activation of the PI3K/AKT, RAS/ERK and JAK/STAT pathways. These pathways predominantly lead to activation or inhibition of transcription factors that regulate expression of both pro- and anti-apoptotic proteins effectively blocking the apoptotic pathway. In cancer, EGF signaling pathways are often dysfunctional and targeted therapies that block EGF signaling have been successful in treating cancers. In this review, we will discuss the EGF survival signaling network, how it cross-talks with the apoptotic signaling pathways and the therapeutic drugs targeting the EGF survival pathway used to treat cancers.

Double immunofluorescence shows coexpression of Bcl-x with GFAP in a variety of glial lesions

Bcl-x is an important member of the bcl-2 family of proteins that has been shown to be expressed by both native nervous system tissue and several nervous system tumors. Its anti-apoptotic activity is believed to contribute to nervous system tumorigenesis. We seek to compare the staining characteristics of Bcl-x and GFAP in various neuronal and glial lesions, both neoplastic and non-neoplastic. We also use a double immunofluorescence technique to assess for coexpression of Bcl-x and GFAP by the same lesional cells. Forty cases of brain tumors and reactive brain conditions were reviewed. The former included astrocytomas, GBMs, ependymomas, oligodendrogliomas, gangliogliomas, subependymomas and neurocytomas. The latter included cases of gliosis, cerebritis and mesial temporal sclerosis. Immunohistochemistry for Bcl-x and GFAP was performed. Double immunofluorescent labeling using antibodies to both GFAP and Bcl-x was also carried out. Expression of Bcl-x closely follows that of GFAP with strong expression in both reactive astrocytes and astrocytomas. There is more focal expression in other gliomas. Immunostaining for Bcl-x is generally more intense and distinct, compared to that for GFAP. Expression of both GFAP and Bcl-x is more focal in oligodendrogliomas, with staining of mainly intervening astrocytic processes. Double immunolabelling confirms the coexpression of Bcl-x and GFAP in various gliomas and reactive brain conditions. As immunostaining for Bcl-x is generally more distinct and intense than that for GFAP, it may serve as a useful alternative to help highlight glial cells in selected diagnostic settings.

Gentamicin causes apoptosis at low concentrations in renal LLC-PK1 cells subjected to electroporation

Gentamicin accumulates in the lysosomes of kidney proximal tubular cells and causes apoptosis at clinically relevant doses. Gentamicin-induced apoptosis can be reproduced with cultured renal cells, but only at high extracellular concentrations (1 to 3 mM; 0.4 to 1.2 g/liter) because of its low level of uptake. We recently showed that gentamicin-induced apoptosis in LLC-PK1 cells involves a rapid (2-h) permeabilization of lysosomes and activation of the mitochondrial pathway of apoptosis (10 h). We now examine whether the delivery of gentamicin to the cytosol by electroporation would sensitize LLC-PK1 cells to apoptosis. Cells were subjected to eight pulses (1 ms) at 800 V/cm (square waves) in the presence of gentamicin (3 microM to 3 mM; 1.2 mg/liter to 1.2 g/liter); returned to gentamicin-free medium; and examined at 8 h for their Bax (a marker of mitochondrial pathway activation) contents by Western blotting and competitive reverse transcriptase PCR and at 24 h for apoptosis by 4',6'-diamidino-2'-phenylindole staining (confirmed by electron microscopy) and for necrosis (by determination of lactate dehydrogenase release). Nonelectroporated cells were incubated with gentamicin for 8 and 24 h. Significant increases in Bax levels (8 h) and apoptosis (24 h) were detected with 0.03 mM (13.2 mg/liter) gentamicin in electroporated cells compared with those achieved with 2 mM (928 mg/liter) in incubated cells. The increase in the Bax level was not associated with an increase in the level of its mRNA but was associated with the accumulation of ubiquitinated forms (probably as a result of impairment of its degradation by the proteasome). Assay of cell-associated gentamicin showed a marked, immediate, but transient accumulation in electroporated cells, whereas a slow, steady uptake was detected in incubated cells. The data indicate that cytosolic gentamicin triggers apoptosis. Sequestration of gentamicin in lysosomes would, to some extent, protect against apoptosis.

Bcl-xL increases axonal numbers but not axonal elongation from rat retinal explants

The Bcl-2 family of proteins has been characterized as a key regulator of cell death programs. In addition, these proteins also play important roles in cellular differentiation, such as axonal growth. The role of Bcl-2 family members on axonal regeneration and neurite extension has been controversial so far. Here, we examine the influence of Bcl-x(L) on axonal regeneration from adult retina explants in vitro. We delivered recombinant Bcl-x(L) into retinal tissue, mediated by the Tat-protein transduction domain, and observed its effect on retinal axon extension. We found that Bcl-x(L) increased the number of regenerating neurites, but did not increase their length. Our results indicate that Bcl-x(L) stimulates axonal initiation but not axonal elongation after crush injury to retinal explants, without altering the number of surviving neurons.

Proteomics analysis of apoptosis-regulating proteins in tissues with different radiosensitivity

The aim of this study was to identify of radiosusceptibility proteins in tissues with different radiosensitivity. C3H/HeJ mice were exposed to 10 Gy. The tissues were processed for proteins extraction and were analyzed by 2-dimensional electrophoresis. The proteins were identified by matrix-assisted laser desorption ionizing time-of-flight mass spectrometry and validated by immunohistochemical staining and Western blotting. The peaks of apoptosis levels were 35.3 +/- 1.7% and 0.6 +/- 0.2% in the spleen and the liver, respectively, after ionizing radiation. Analysis of liver tissue showed that the expression level of ROS related proteins such as cytochrome c, glutathione S transferase, NADH dehydrogenase and peroxiredoxin VI increased after radiation. The expression level of cytochrome c increased to 3-fold after ionizing radiation in both tissues. However in spleen tissue, the expression level of various kinds of apoptosis regulating proteins increased after radiation. These involved iodothyronine, CD 59A glycoprotein precursor, fas antigen and tumor necrosis factor -inducible protein TSG-6n precursor after radiation. The difference in the apoptosis index between the liver and spleen tissues is closely associated with the expression of various kinds of apoptosis-related proteins. The result suggests that the expression of apoptosis-related protein and redox proteins play important roles in this radiosusceptibility.

The role of phospholipid hydroperoxide glutathione peroxidase isoforms in murine embryogenesis

Phospholipid hydroperoxide glutathione peroxidase (GPx4) is a selenocysteine-containing enzyme, and three different isoforms (cytosolic, mitochondrial, and nuclear) originate from the GPx4 gene. Homozygous GPx4-deficient mice die in utero at midgestation, since they fail to initiate gastrulation and do not develop embryonic cavities. To investigate the biological basis for embryonic lethality, we first explored expression of the GPx4 in adult murine brain and found expression of the protein in cerebral neurons. Next, we profiled mRNA expression during the time course of embryogenesis (embryonic days 6.5-17.5 (E6.5-17.5)) and detected mitochondrial and cytosolic mRNA species at high concentrations. In contrast, the nuclear isoform was only expressed in small amounts. Cytosolic GPx4 mRNA was present at constant levels (about 100 copies per 1000 copies of glyceraldehyde-3-phosphate dehydrogenase mRNA), whereas nuclear and mitochondrial isoforms were down-regulated between E14.5 and E17.5. In situ hybridization indicated expression of GPx4 isoforms in all developing germ layers during gastrulation and in the somite stage in the developing central nervous system and in the heart. When we silenced expression of GPx4 isoforms during in vitro embryogenesis using short interfering RNA technology, we observed that knockdown of mitochondrial GPx4 strongly impaired segmentation of rhombomeres 5 and 6 during hindbrain development and induced cerebral apoptosis. In contrast, silencing expression of the nuclear isoform led to retardations in atrium formation. Taken together, our data indicate specific expression of GPx4 isoforms in embryonic brain and heart and strongly suggest a role of this enzyme in organogenesis. These findings may explain in part intrauterine lethality of GPx4 knock-out mice.

Renal failure causes early death of bcl-2 deficient mice

BCL-2 functions as a death repressor molecule in an evolutionary conserved cell death pathway. Inactivation of bcl-2 in mice results in pleiotropic effects including postnatal growth retardation, massive apoptosis in lymphoid tissues, polycystic kidney disease (PKD) and shortened lifespan. To evaluate the influence of the affected bcl-2 deficient kidneys on the postnatal development and lifespan of bcl-2 knockout mice we used "the rescue of (n-1) affected tissues" strategy. According to this strategy bcl-2 heterozygous animals were crossed with H2K-hbcl-2 transgenic mice expressing human BCL-2 in most tissues and organs excluding the kidney. Overexpression of hBCL-2 in bcl-2-/- mice rescues growth retardation, normalizes and protects the hematolymphoid system from gamma-radiation. However, the hbcl-2 transgene is not expressed in kidneys and the rescued mice have PKD and a shortened lifespan. Thus, our results indicated that PKD is the main reason of early mortality in bcl-2 deficient mice. Moreover, we have created mouse model, similar to the kidney specific knockout of bcl-2. Such models can be useful to study the influence of bcl-2 or other gene deficiency in individual organs (or tissues) on development and ageing of whole organism.

Death receptor and mitochondrial pathways are involved in germ cell apoptosis in an experimental model of autoimmune orchitis

BACKGROUND

Studies on experimental autoimmune orchitis (EAO) have helped to elucidate immunological mechanisms involved in testicular damage. We previously demonstrated that EAO is characterized by lymphomononuclear cell infiltrates and apoptosis of spermatocytes and spermatids expressing Fas and TNFR1. The aim of this work was to characterize the pathways involved in germ cell apoptosis in EAO and to determine the involvement of the Bcl-2 protein family in this process.

METHODS AND RESULTS

EAO was induced in rats by immunization with testicular homogenate (TH) and adjuvants, whereas control (C) rats were injected with saline solution and adjuvants. Testis of EAO rats showed procaspase 8 cleavage products (western blot) with high caspase 8 activity. Cytochrome c content increased in the cytosol and decreased in the mitochondrial fraction of testis from EAO rats compared with C, concomitant with increased caspase 9 activity. Bax was mainly expressed in spermatocytes and spermatids and Bcl-2 in basal germ cells (immunohistochemistry). Baxbeta isoform content increased in EAO rat testis compared with C, whereas content of Baxalpha remained unchanged (western blot). However, Baxalpha content decreased in the cytosol and increased in the mitochondrial and endoplasmic reticulum (ER)-enriched fractions of testis from EAO rats compared with C (western blot). Bcl-2 content also increased in the testes of EAO rats.

CONCLUSIONS

Our results demonstrated that extrinsic, mitochondrial and possibly ER pathways are inducers of germ cell apoptosis in EAO and that Bax and Bcl-2 proteins modulate this process.

Insulin-like growth factor-1 treatment prevents anti-Fas antibody-induced apoptosis in endplate chondrocytes

STUDY DESIGN

In vitro investigation of vertebral endplate chondrocyte apoptosis.

OBJECTIVES

To determine whether Fas antibody caused apoptosis in endplate chondrocytes, and whether insulin-like growth factor-1 (IGF-1) inhibited this effect. Integrin-alpha1 and focal adhesion kinase (FAK) expression in conjunction with apoptosis was also investigated.

SUMMARY OF BACKGROUND DATA

Binding of Fas antibody to Fas mimics Fas-FasL ligation, which causes apoptosis. IGF-1 has been shown to have anti-apoptotic effects.

MATERIALS AND METHODS

Rat cervical endplate chondrocytes were cultured and treated with Fas antibody, with or without IGF-1. Cellular morphology was examined by microscopy. Apoptotic changes were evaluated by transmission electron microscopy, TUNEL staining, and immunostaining. Apoptosis-induced changes in the expression of integrin-alpha1 chain and FAK were also investigated.

RESULTS

Endplate chondrocytes were able to be cultured; a chondrocytic phenotype was maintained. Fas antibody induced apoptosis in endplate chondrocytes; this was confirmed by TUNEL staining. Bcl-2 expression was decreased by Fas antibody, while Bax expression increased. Integrin-alpha1 and FAK expression was decreased by Fas antibody. IGF-1 treatment inhibited these Fas antibody-induced changes.

CONCLUSIONS

Fas antibody induces apoptosis and decreases Integrin-alpha1 and FAK expression in cultured endplate chondrocytes; IGF-1 is protective against these changes.

Bcl-2 immunoreactivity in human cutaneous Meissner and Pacinian corpuscles

The occurrence and distribution of Bcl-2, a protein involved in the death-life cell pathways, was investigated in the peripheral sensory nervous system of healthy adult humans, including lumbar dorsal root ganglia, nerve trunks and glabrous skin (to analyze sensory corpuscles) using Western blot and immunohistochemistry. The antibody used labelled a protein of 26 kDa of estimated molecular weight corresponding with Bcl-2. Immunohistochemistry showed that only a neuronal population in dorsal root ganglia, some axons in peripheral nerves and the axon supplying Meissner and Pacinian corpuscles contained Bcl-2, whereas peripheral glial cells (i.e. satellite glial cells, Schwann cell, and lamellar cells of sensory corpuscles) did not. These results suggest that in normal conditions, Bcl-2 is only present in some neuronal, but not glial, elements of the sensory peripheral nervous system. The functional significance, if any, of these results remains to be determined.

Molecular mechanism investigation of cycloheximide-induced hepatocyte apoptosis in rat livers by morphological and microarray analysis

Male F344 rats were intravenously treated with 6 mg/kg cycloheximide (CHX), and microarray analysis was conducted on their livers 1, 2 and 6h after the CHX treatment. The histopathological examination and serum chemistry results indicated a mild hepatic cell death 2 and 6h after the CHX treatment, respectively. Multi-focal hepatocellular necrosis with slight neutrophil infiltration was observed 6h after the CHX treatment. The TUNEL staining results showed that the number of apoptotic hepatocytes was the highest 2h after the CHX treatment. Dramatic increases in the mRNA levels of ATF3 and CHOP genes, both of which were reported to play roles in the ER stress-mediated apoptosis pathway, were observed from 1h after the CHX treatment. In addition, increase of GADD45, p21 and p53 mRNA levels also suggested a time course-related stimulation of hepatocellular apoptotic signals. These results suggest that the hepatocyte apoptosis induced by the CHX treatment is triggered by ER stress. The hepatic mRNA levels of proinflammatory genes, such as TNFalpha, IL-1alpha and beta, were also increased 1 and 2h after the CHX treatment, supposedly mediated by the activated Kupffer cells engulfing the apoptotic hepatocytes.

Teratogen-induced apoptotic cell death: Does the apoptotic machinery act as a protector of embryos exposed to teratogens?

Considerable evidence has been collected demonstrating that many teratogens induce apoptotic cell death in embryonic structures that turn out to be malformed in fetuses and newborns. Apoptosis is a genetically regulated process that is realized by the activation of death and pro-survival signaling cascades, and the interplay between these cascades determines whether the cell exposed to apoptotic stimuli dies or survives. Therefore, there is intense interest in understanding how the apoptotic machinery functions in embryos exposed to teratogens. However, the interpretation of the results obtained remains problematic. The main problem is that excessive embryonic cell death, regardless of its nature, if uncompensated for, ultimately leads to maldevelopment or embryonic death. Therefore, we can easily interpret results when the intensity of teratogen-induced cell death and the severity or incidence of teratogen-induced anomalies directly correlate with each other. However, when teratogen-induced cell death is not followed by the formation of anomalies, a usual explanation is that teratogen-induced apoptotic cell death contributes to the renewal of teratogen-targeted cell populations by promoting the removal of injured cells. It is clear that such an explanation leaves vague the role of the anti-apoptotic signaling mechanism (and, hence, the apoptotic machinery as a whole) with respect to protecting the embryo against teratogenic stress. In this review, we summarize the data from studies addressing the function of the apoptotic machinery in embryos exposed to teratogens, and then we discuss approaches to interpreting the results of these studies. We hypothesize that activation of a proapoptotic signaling in teratogen-targeted cell populations is a necessary condition for an anti-apoptotic signaling that counteracts the process of maldevelopment to be activated. If such a scenario is true, we need to modify our approaches to choosing molecular targets for studies addressing this topic.

Molecular characterization of FK-506 binding protein 38 and its potential regulatory role on the anti-apoptotic protein Bcl-2

The immunosuppressant FK-506 binding protein 38 (FKBP38) is localized at the mitochondrial membrane and appears to play an important role in apoptosis. Recent reports about the potential functions of FKBP38 in apoptosis appear to be controversial. To further understand the biological function of FKBP38, here, we studied its molecular characteristics and a potential regulatory role on the anti-apoptotic protein Bcl-2. Our results suggest that FKBP38 appears to show chaperone activities in the citrate synthase aggregation assays during thermal denaturation and affect solubility of Bcl-2 when they are co-expressed. The FKBP family proteins bind the immunosuppressive drug FK-506 through the FK-506 binding domain and consequently inhibit the activity of calcineurin. In this study, from our NMR studies and calcineurin assays in vitro, we demonstrate that the N-terminal fragment of FKBP38 which contains the FK-506 binding domain does not bind FK-506 at molecular level. Lastly, to investigate the effect of FKBP38 on Bcl-2, we suppressed FKBP38 by RNA interference (RNAi) of FKBP38. Our results suggest that the suppression of FKBP38 appears to make Bcl-2 unstable or unprotected from degradation in an unknown mechanism.

T-cadherin protects endothelial cells from oxidative stress-induced apoptosis

In vascular tissue, T-cadherin (T-cad) is up-regulated in vivo under disease conditions associated with oxidative stress and concomitant cell migration, proliferation and apoptosis/survival. Using cultures of human umbilical vein endothelial cells (HUVEC), we examined whether there is a functional relationship between oxidative stress, T-cad expression, and cell survival status. Culture of HUVEC under conditions of oxidative stress (e.g., serum deprivation, inclusion of H2O2) resulted in increased T-cad expression. Oxidative stress-induced increases in T-cad were inhibited by the free radical-scavenging antioxidant, N-acetylcysteine, and the flavin-containing oxidase inhibitor, diphenyleneiodonium. Thus reactive oxygen species (ROS) contribute to stress-induced elevation of T-cad in HUVEC. Compared with control cells, HUVEC overexpressing T-cad (T-cad+-HUVEC) had higher phosphorylation levels for phosphatidylinositol 3-kinase (PI3K) target Akt and mTOR target p70(S6K) (survival pathway regulators), but lower levels for p38MAPK (death pathway regulator). T-cad+-HUVEC exposed to stress (serum-deprivation, TNF-alpha, actinomycin D, staurosporine) exhibited reduced caspase activation together with increased cell survival. Protection against stress-induced apoptosis in T-cad+-HUVEC was abrogated by either PI3K-inhibitor wortmannin or mTOR-inhibitor rapamycin. We conclude that T-cad overexpression in HUVEC protects against stress-induced apoptosis through activation of the PI3K/Akt/mTOR survival signal pathway and concomitant suppression of the p38 MAPK proapoptotic pathway. ROS-induced changes in T-cad expression may play an important role in controlling tissue cellularity during vascular remodeling.

Phylogenomics of Life-Or-Death Switches in Multicellular Animals: Bcl-2, BH3-Only, and BNip Families of Apoptotic Regulators

In this report, we conducted a comprehensive survey of Bcl-2 family members, a divergent group of proteins that regulate programmed cell death by an evolutionarily conserved mechanism. Using comparative sequence analysis, we found novel sequences in mammals, nonmammalian vertebrates, and in a number of invertebrates. We then asked what conclusions could be drawn from phyletic distribution, intron/exon structures, sequence/structure relationships, and phylogenetic analyses within the updated Bcl-2 family. First, multidomain members having a sequence pattern consistent with the conservation of the Bcl-X(L)/Bax/Bid topology appear to be restricted to multicellular animals and may share a common ancestry. Next, BNip proteins, which were originally identified based on their ability to bind to E1B 19K/Bcl-2 proteins, form three independent monophyletic branches with different evolutionary history. Lastly, a set of Bcl-2 homology 3-only proteins with unrelated secondary structures seems to have evolved after the origin of Metazoa and exhibits diverse expansion after speciation during vertebrate evolution.

Harnessing wound healing and regeneration for tissue engineering

Biomedical science has made major advances in understanding how cells grow into functioning tissue and the signalling mechanisms used to achieve this are slowly being dissected. Tissue engineering is the application of that knowledge to the building or repairing of organs, including skin, the largest organ in the body. Generally, engineered tissue is a combination of living cells and a supporting matrix. Besides serving as burn coverings, engineered skin substitutes can help patients with diabetic foot ulcers. Today, most of these ulcers are treated with an approach that includes antibiotics, glucose control, special shoes and frequent cleaning and bandaging. The results of such treatments are often disappointing and ineffectual, and scarring remains a major problem, mechanically, cosmetically and psychologically. Within our group we are attempting to address this by investigating novel approaches to skin tissue engineering. We are identifying novel therapeutic manipulations to improve the degree of integration between a tissue engineered dermal construct and the host by both molecular manipulation of growth factors but also by understanding and harnessing mechanisms of regenerative biology. For the purpose of this summary, we will concentrate primarily on the latter of these two approaches in that we have identified a novel mouse mutant that completely and perfectly regenerates skin and cartilaginous components following ear injury. This experimental animal will allow us to characterize not only novel genes involved in the regeneration process but also to utilize cells from such animals in artificial skin equivalents to assess their behaviour compared with normal cells. This approach should allow us to create a tissue-engineered substitute, which more closely resembles the normal regional microanatomy and physiology of the skin, allowing better integration to the host with minimal or no scarring.

Antiproliferative and proapoptotic effects of raloxifene on uterine leiomyomas in postmenopausal women

OBJECTIVE

To study the cell effects of raloxifene on uterine and leiomyoma tissue in postmenopausal women.

DESIGN

Prospective, randomized, double-blind, placebo-controlled study.

SETTING

Department of Obstetrics and Gynecology, University "Magna Graecia" of Catanzaro, Italy.

PATIENT(S)

Forty postmenopausal women affected by uterine leiomyomas and selected for hysterectomy.

INTERVENTION(S)

Treatment for three cycles of 28 days with raloxifene at a dose of 180 mg/day orally (raloxifene group) or placebo tablets (3 tablets/day orally) (placebo group).

MAIN OUTCOME MEASURE(S)

Uterine and leiomyoma dimensions were measured in each subject at entry and before surgery. On leiomyomas and homologous myometrium the proliferating cell nuclear antigen (PCNA)-positive cells/total cells (PCNA/TC) and the Bcl-2-positive cells/Bax-positive cells (Bcl-2/Bax) ratios (%), as proliferation and apoptotic indexes, respectively, were measured.

RESULT(S)

After treatment, uterine and leiomyoma sizes were significantly changed in comparison with baseline and the placebo group. PCNA/TC and Bcl-2/Bax ratios were significantly higher in leiomyomas than in homologous myometrium. A significant difference was detected in PCNA/TC between the myometrium of the raloxifene and control groups, whereas no difference was observed in the Bcl-2/Bax ratio. A significant difference in PCNA/TC and Bcl-2/Bax ratios was detected in leiomyoma tissue between the raloxifene group and controls.

CONCLUSION(S)

In postmenopausal women, raloxifene administration reduces uterine leiomyomas by exerting a cell antiproliferative and proapoptotic action.

Maternal diet programs embryonic kidney gene expression

Human epidemiological data associating birth weight with adult disease suggest that organogenesis is "programmed" by maternal diet. In rats, protein restriction in pregnancy produces offspring with fewer renal glomeruli and higher systemic blood pressures than controls. We tested the hypothesis that maternal diet alters gene expression in the metanephros, the precursor of the definitive mammalian kidney. We demonstrated that maternal low-protein diet initiated when pregnancy starts and maintained to embryonic day 13, when the metanephros consists of mesenchyme surrounding a once-branched ureteric bud, is sufficient to significantly reduce glomerular numbers in offspring by about 20%. As assessed by representational difference analyses and real-time quantitative polymerase chain reactions, low-protein diet modulated gene expression in embryonic day 13 metanephroi. In particular, levels of prox-1, the ortholog of Drosophila transcription factor prospero, and cofilin-1, a regulator of the actin cytoskeleton, were reduced. During normal metanephrogenesis, prox-1 protein was first detected in mesenchymal cells around the ureteric tree and thereafter in nascent nephron epithelia, whereas cofilin-1 immunolocalized to bud derivatives and condensing mesenchyme. Previously, we reported that low-protein diets increased mesenchymal apoptosis cells when metanephrogenesis began and thereafter reduced numbers of precursor cells. Collectively, these studies prove that the maternal diet programs the embryonic kidney, altering cell turnover and gene expression at a time when nephrons and glomeruli have yet to form. The human implication is that the maternal diet ingested between conception and 5- 6-wk gestation contributes to the variation in glomerular numbers that are known to occur between healthy and hypertensive populations.

Attenuation of retinal vascular development and neovascularization during oxygen-induced ischemic retinopathy in Bcl-2−/− mice

Bcl-2 is a death repressor that protects cells from apoptosis mediated by a variety of stimuli. Bcl-2 expression is regulated by both pro- and anti-angiogenic factors; thus, it may play a central role during angiogenesis. However, the role of bcl-2 in vascular development and growth of new vessels requires further delineation. In this study, we investigated the physiological role of bcl-2 in development of retinal vasculature and retinal neovascularization during oxygen-induced ischemic retinopathy (OIR). Mice deficient in bcl-2 exhibited a significant decrease in retinal vascular density compared to wild-type mice. This was attributed to a decreased number of endothelial cells and pericytes in retinas from bcl-2-/- mice. We observed, in bcl-2-/- mice, delayed development of retinal vasculature and remodeling, and a significant decrease in the number of major arteries, which branch off from near the optic nerve. Interestingly, hyaloid vessel regression, an apoptosis-dependent process, was not affected in the absence of bcl-2. The retinal vasculature of bcl-2-/- mice exhibited a similar sensitivity to hyperoxia-mediated vessel obliteration compared to wild-type mice during OIR. However, the degree of ischemia-induced retinal neovascularization was significantly reduced in bcl-2-/- mice. These results suggest that expression of bcl-2 is required for appropriate development of retinal vasculature as well as its neovascularization during OIR.

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