Lentiviral vector-mediated RNA interference targeted against prohibitin inhibits apoptosis of the retinoic acid-resistant acute promyelocytic leukemia cell line NB4-R1

Role of Prohibitins in Aging and Therapeutic Potential Against Age-Related Diseases

A decline in mitochondrial function has long been associated with age-related health decline. Several lines of evidence suggest that interventions that stimulate mitochondrial autophagy (mitophagy) can slow aging and prolong healthy lifespan. Prohibitins (PHB1 and PHB2) assemble at the mitochondrial inner membrane and are critical for mitochondrial homeostasis. In addition, prohibitins (PHBs) have diverse roles in cell and organismal biology. Here, we will discuss the role of PHBs in mitophagy, oxidative phosphorylation, cellular senescence, and apoptosis. We will also discuss the role of PHBs in modulating lifespan. In addition, we will review the links between PHBs and diseases of aging. Finally, we will discuss the emerging concept that PHBs may represent an attractive therapeutic target to counteract aging and age-onset disease.

Prohibitin 1 (PHB1) controls growth and development and regulates proliferation and apoptosis in Schistosoma japonicum

Schistosomiasis is a zoonotic parasitic disease caused by the trematode blood flukes of the genus Schistosoma. The prodigious egg output of females is the main cause of the disease in definitive hosts, while the female worm relies on continuous pairing with the male worm to fuel the growth and maturation of the reproductive organs and egg production. Prohibitin, which contains the functionally interdependent PHB1 and PHB2 subunits in human and some other species, has been proposed to participate in the cell proliferation and apoptosis regulation in mammals. However, little is known about the function of PHB homolog in the growth and reproductive development of schistosomes. Here, we reported the Phb1 gene that was structurally and evolutionarily conserved in Schistosoma japonicum when compared with that of other species from Caenorhabditis elegans to human. Real-time PCR detected that SjPhb1 was highly transcribed in the vitellaria of female worms. SjPhb1 knockdown achieved through the dsRNA-mediated RNAi in vivo resulted in retarded growth, decreased pairing, and fecundity in adult worms, as well as attenuated pathogenicity or virulence of worms to their hosts. Cell proliferation and apoptosis examination found decreased cell proliferation and increased cell apoptosis in SjPhb1 dsRNA-treated worms. Therefore, our study provides the first characterization of S. japonicum PHB1 and reveals its fundamental role in the regulation of growth and development of S. japonicum by specific dsRNA-mediated RNAi in vivo. Our findings prompt for a promising molecular of schistosomes that can be targeted to effectively retard the growth and development of the schistosomes.

Significance of prohibitin domain family in tumorigenesis and its implication in cancer diagnosis and treatment

Prohibitin (PHB) was originally isolated and characterized as an anti-proliferative gene in rat liver. The evolutionarily conserved PHB gene encodes two human protein isoforms with molecular weights of ~33 kDa, PHB1 and PHB2. PHB1 and PHB2 belong to the prohibitin domain family, and both are widely distributed in different cellular compartments such as the mitochondria, nucleus, and cell membrane. Most studies have confirmed differential expression of PHB1 and PHB2 in cancers compared to corresponding normal tissues. Furthermore, studies verified that PHB1 and PHB2 are involved in the biological processes of tumorigenesis, including cancer cell proliferation, apoptosis, and metastasis. Two small molecule inhibitors, Rocaglamide (RocA) and fluorizoline, derived from medicinal plants, were demonstrated to interact directly with PHB1 and thus inhibit the interaction of PHB with Raf-1, impeding Raf-1/ERK signaling cascades and significantly suppressing cancer cell metastasis. In addition, a short peptide ERAP and a natural product xanthohumol were shown to target PHB2 directly and prohibit cancer progression in estrogen-dependent cancers. As more efficient biomarkers and targets are urgently needed for cancer diagnosis and treatment, here we summarize the functional role of prohibitin domain family proteins, focusing on PHB1 and PHB2 in tumorigenesis and cancer development, with the expectation that targeting the prohibitin domain family will offer more clues for cancer therapy.

Targeting prohibitins induces apoptosis in acute myeloid leukemia cells

Fluorizoline is a new synthetic molecule that induces apoptosis by selectively targeting prohibitins (PHBs). In this study, the pro-apoptotic effect of fluorizoline was assessed in two cell lines and 21 primary samples from patients with debut of acute myeloid leukemia (AML). Fluorizoline induced apoptosis in AML cells at concentrations in the low micromolar range. All primary samples were sensitive to fluorizoline irrespectively of patients' clinical or genetic features. In addition, fluorizoline inhibited the clonogenic capacity and induced differentiation of AML cells. Fluorizoline increased the mRNA and protein levels of the pro-apoptotic BCL-2 family member NOXA both in cell lines and primary samples analyzed. These results suggest that targeting PHBs could be a new therapeutic strategy for AML.

Multifaceted role of prohibitin in cell survival and apoptosis

Human eukaryotic prohibitin (prohibitin-1 and prohibitin-2) is a membrane protein with different cellular localizations. It is involved in multiple cellular functions, including energy metabolism, proliferation, apoptosis, and senescence. The subcellular localization of prohibitin may determine its functions. Membrane prohibitin regulate the cellular signaling of membrane transport, nuclear prohibitin control transcription activation and the cell cycle, and mitochondrial prohibitin complex stabilize the mitochondrial genome and modulate mitochondrial dynamics, mitochondrial morphology, mitochondrial biogenesis, and the mitochondrial intrinsic apoptotic pathway. Moreover, prohibitin can translocates into the nucleus or the mitochondria under apoptotic signals and the subcellular shuttling of prohibitin is necessary for apoptosis process. Apoptosis is the process of programmed cell death that is important for the maintenance of normal physiological functions. Consequently, any alteration in the content, post-transcriptional modification (i.e. phosphorylation) or the nuclear or mitochondrial translocation of prohibitin may influence cell fate. Understanding the mechanisms of the expression and regulation of prohibitin may be useful for future research. This review provides an overview of the multifaceted and essential roles played by prohibitin in the regulation of cell survival and apoptosis.

Paeoniflorin ameliorates acute myocardial infarction of rats by inhibiting inflammation and inducible nitric oxide synthase signaling pathways

Paeoniflorin (PF) is the main active component of the commonly used Traditional Chinese Medicine peony, Paeonia Suffruticosa. PF has diverse biological functions and exhibits anti‑oxidative, anti‑inflammatory and anti‑apoptotic activity. Inducible nitric oxide synthase (iNOS) is a catalyzing enzyme that is involved in the synthesis of nitric oxide (NO). NO has an important regulatory role in the cardiovascular, immune and nervous systems. PF has previously been demonstrated to inhibit the gene expression of iNOS. The present study aimed to identify a potentially novel cytoprotective function of PF, and to elucidate its effects against myocardial ischemic damage in a rat model of acute myocardial infarction (AMI). PF was able to significantly decrease the myocardial infarct size as well as the activities of creatine kinase (CK), the MB isoenzyme of CK, lactate dehydrogenase and cardiac troponin T. In addition, in the PF‑treated groups, the expression levels of tumor necrosis factor‑α, interleukin (IL)‑1β, IL‑6 and nuclear factor‑κB were markedly inhibited. Furthermore, treatment with PF inhibited the activities and protein expression levels of iNOS. Decreased caspase‑3 and caspase‑9 activities were also observed in the AMI rat model treated with various doses of PF. The results of the present study indicated that the cardioprotective effects of PF may be associated with the inhibition of inflammation and iNOS signaling pathways.

Protective effect of alpha-synuclein knockdown on methamphetamine-induced neurotoxicity in dopaminergic neurons

The over-expression of α-synuclein is a major factor in the death of dopaminergic neurons in a methamphetamine-induced model of Parkinson's disease. In the present study, α-synuclein knockdown rats were created by injecting α-synuclein-shRNA lentivirus stereotaxically into the right striatum of experimental rats. At 2 weeks post-injection, the rats were injected intraperitoneally with methamphetamine to establish the model of Parkinson's disease. Expression of α-synuclein mRNA and protein in the right striatum of the injected rats was significantly downregulated. Food intake and body weight were greater in α-synuclein knockdown rats, and water intake and stereotyped behavior score were lower than in model rats. Striatal dopamine and tyrosine hydroxylase levels were significantly elevated in α-synuclein knockdown rats. Moreover, superoxide dismutase activity was greater in α-synuclein knockdown rat striatum, but the levels of reactive oxygen species, malondialdehyde, nitric oxide synthase and nitrogen monoxide were lower compared with model rats. We also found that α-synuclein knockdown inhibited methamphetamine-induced neuronal apoptosis. These results suggest that α-synuclein has the capacity to reverse methamphetamine-induced apoptosis of dopaminergic neurons in the rat striatum by inhibiting oxidative stress and improving dopaminergic system function.

Curcumin inhibits mitochondrial injury and apoptosis from the early stage in EAE mice

The exact pathophysiological change concerning mitochondrial injury and oligodendrocyte apoptosis in MS and EAE model is still unknown. Whether curcumin is able to inhibit mitochondrial injury and suppress the apoptosis in the early stages of MS/EAE is still unclear. We first explored mitochondrial injury and apoptosis at different time points p.i. in C57 BL/6 EAE mice. We then explored the effects of curcumin on mitochondria and apoptosis. Results showed that mitochondrial injury can be observed 3 days p.i. Apoptosis in the spinal cord occurred 3 days p.i. and the apoptotic cells were shown to be oligodendrocytes and neuronal cells. Curcumin significantly reduced the number of apoptotic cells and inhibited the upregulation of cyt-c, caspase-9, and caspase-3 at 7 days p.i. in the EAE mice. These observations demonstrate that mitochondrial injury and oligodendrocyte/neuronal apoptosis occur in the early stages of EAE. Curcumin can inhibit apoptosis in EAE mice which maybe act through protection of mitochondrial injury and inhibition of the intrinsic apoptotic pathway.