IP3R2 regulates apoptosis by Ca2+ transfer through mitochondria-ER contacts in hypoxic photoreceptor injury.

Mitochondria-associated ER membranes (MAMs) are contact sites that enable bidirectional communication between the ER (endoplasmic reticulum) and mitochondria, including the transfer of Ca2+ signals. MAMs are essential for mitochondrial function and cellular energy metabolism. However, unrestrained Ca2+ transfer to the mitochondria can lead to mitochondria-dependent apoptosis. IP3R2 (Inositol 1,4,5-trisphosphate receptor 2) is an important intracellular Ca2+ channel. This study investigated the contribution of IP3R2-MAMs to hypoxia-induced apoptosis in photoreceptor cells. A photoreceptor hypoxia model was established by subretinal injection of hyaluronic acid (1%) in C57BL/6 mice and 1% O2 treatment in 661W cells. Transmission electron microscopy (TEM), ER-mitochondria colocalization, and the MAM reporter were utilized to evaluate MAM alterations. Cell apoptosis and mitochondrial homeostasis were evaluated using immunofluorescence (IF), flow cytometry, western blotting (WB), and ATP assays. SiRNA transfection was employed to silence IP3R2 in 661W cells. Upon hypoxia induction, MAMs were significantly increased in photoreceptors both in vivo and in vitro. This was accompanied by the activation of mitochondrial apoptosis and disruption of mitochondrial homeostasis. Elevated MAM-enriched IP3R2 protein levels induced by hypoxic injury led to mitochondrial calcium overload and subsequent photoreceptor apoptosis. Notably, IP3R2 knockdown not only improved mitochondrial morphology but also restored mitochondrial function in photoreceptors by limiting MAM formation and thereby attenuating mitochondrial calcium overload under hypoxia. Our results suggest that IP3R2-MAM-mediated mitochondrial calcium overload plays a critical role in mitochondrial dyshomeostasis, ultimately contributing to photoreceptor cell death. Targeting MAM constitutive proteins might provide an option for a therapeutic approach to mitigate photoreceptor death in retinal detachment.

TRIM25 inhibition attenuates inflammation, senescence, and oxidative stress in microvascular endothelial cells induced by hyperglycemia.

PURPOSES: This work aimed to assess the possible role of TRIM25 in regulating hyperglycemia-induced inflammation, senescence, and oxidative stress in retinal microvascular endothelial cells, all of which exert critical roles in the pathological process of diabetic retinopathy. METHODS: The effects of TRIM25 were investigated using streptozotocin-induced diabetic mice, human primary retinal microvascular endothelial cells cultured in high glucose, and adenoviruses for TRIM25 knockdown and overexpression. TRIM25 expression was evaluated by western blot and immunofluorescence staining. Inflammatory cytokines were detected by western blot and quantitative real-time PCR. Cellular senescence level was assessed by detecting senescent marker p21 and senescence-associated-ß-galactosidase activity. The oxidative stress state was accessed by detecting reactive oxygen species and mitochondrial superoxide dismutase. RESULTS: TRIM25 expression is elevated in the endothelial cells of the retinal fibrovascular membrane from diabetic patients compared with that of the macular epiretinal membrane from non-diabetic patients. Moreover, we have also observed a significant increase in TRIM25 expression in diabetic mouse retina and retinal microvascular endothelial cells under hyperglycemia. TRIM25 knockdown suppressed hyperglycemia-induced inflammation, senescence, and oxidative stress in human primary retinal microvascular endothelial cells while TRIM25 overexpression further aggregates those injuries. Further investigation revealed that TRIM25 promoted the inflammatory responses mediated by the TNF-α/NF-κB pathway and TRIM25 knockdown improved cellular senescence by increasing SIRT3. However, TRIM25 knockdown alleviated the oxidative stress independent of both SIRT3 and mitochondrial biogenesis. CONCLUSION: Our study proposed TRIM25 as a potential therapeutic target for the protection of microvascular function during the progression of diabetic retinopathy.

Diversity, pathogenicity and two new species of pestalotioid fungi (Amphisphaeriales) associated with Chinese Yew in Guangxi, China.

Chinese yew, Taxuschinensisvar.mairei is an endangered shrub native to south-eastern China and is widely known for its medicinal value. The increased cultivation of Chinese yew has increased the incidence of various fungal diseases. In this study, Pestalotioid fungi associated with needle spot of Chinese yew were isolated from Guangxi Province. Based on morphological examinations and multi-locus (ITS, tub2, tef-1α) phylogenies, these isolates were identified to five species, including two new species, Pestalotiopsistaxicola and P.multicolor, two potential novel Neopestalotiopsis species, Neopestalotiopsis sp. 3 and Neopestalotiopsis sp. 4, with a known Pestalotiopsis species (Pestalotiopsistrachycarpicola), firstly recorded from Chinese yew. These two new Pestalotiopsis species were morphologically and phylogenetically distinct from the extant Pestalotioid species in Chinese yew. Pathogenicity and culture characteristic tests of these five Pestalotioid species were also performed in this study. The pathogenicity test results revealed that Neopestalotiopsis sp. 3 can cause diseases in Chinese yew needles. These results have indicated that the diversity of Pestalotioid species associated with Chinese yew was greater than previously determined and provided helpful information for Chinese yew disease diagnosis and management.

TIN2 modulates FOXO1 mitochondrial shuttling to enhance oxidative stress-induced apoptosis in retinal pigment epithelium under hyperglycemia.

Progressive dysfunction of the retinal pigment epithelium (RPE) and the adjacent photoreceptor cells in the outer retina plays a pivotal role in the pathogenesis of diabetic retinopathy (DR). Here, we observed a marked increase in oxidative stress-induced apoptosis in parallel with higher expression of telomeric protein TIN2 in RPE cells under hyperglycemia in vivo and in vitro. Delving deeper, we confirm that high glucose-induced elevation of mitochondria-localized TIN2 compromises mitochondrial activity and weakens the intrinsic antioxidant defense, thereby leading to the activation of mitochondria-dependent apoptotic pathways. Mechanistically, mitochondrial TIN2 promotes the phosphorylation of FOXO1 and its relocation to the mitochondria. Such translocation of transcription factor FOXO1 not only promotes its binding to the D-loop region of mitochondrial DNA-resulting in the inhibition of mitochondrial respiration-but also hampers its availability to nuclear target DNA, thereby undermining the intrinsic antioxidant defense. Moreover, TIN2 knockdown effectively mitigates oxidative-induced apoptosis in diabetic mouse RPE by preserving mitochondrial homeostasis, which concurrently prevents secondary photoreceptor damage. Our study proposes the potential of TIN2 as a promising molecular target for therapeutic interventions for diabetic retinopathy, which emphasizes the potential significance of telomeric proteins in the regulation of metabolism and mitochondrial function. Created with BioRender ( https://www.biorender.com/ ).

PFKFB3 in neovascular eye disease: unraveling mechanisms and exploring therapeutic strategies.

BACKGROUND: Neovascular eye disease is characterized by pathological neovascularization, with clinical manifestations such as intraocular exudation, bleeding, and scar formation, ultimately leading to blindness in millions of individuals worldwide. Pathologic ocular angiogenesis often occurs in common fundus diseases including proliferative diabetic retinopathy (PDR), age-related macular degeneration (AMD), and retinopathy of prematurity (ROP). Anti-vascular endothelial growth factor (VEGF) targets the core pathology of ocular angiogenesis. MAIN BODY: In recent years, therapies targeting metabolism to prevent angiogenesis have also rapidly developed, offering assistance to patients with a poor prognosis while receiving anti-VEGF therapy and reducing the side effects associated with long-term VEGF usage. Phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3), a key enzyme in targeted metabolism, has been shown to have great potential, with antiangiogenic effects and multiple protective effects in the treatment of neovascular eye disease. In this review, we summarize the mechanisms of common types of neovascular eye diseases; discuss the protective effect and potential mechanism of targeting PFKFB3, including the related inhibitors of PFKFB3; and look forward to the future exploration directions and therapeutic prospects of PFKFB3 in neovascular eye disease. CONCLUSION: Neovascular eye disease, the most common and severely debilitating retinal disease, is largely incurable, necessitating the exploration of new treatment methods. PFKFB3 has been shown to possess various potential protective mechanisms in treating neovascular eye disease. With the development of several drugs targeting PFKFB3 and their gradual entry into clinical research, targeting PFKFB3-mediated glycolysis has emerged as a promising therapeutic approach for the future of neovascular eye disease.

TIN2-mediated reduction of mitophagy induces RPE senescence under high glucose.

The telomere-associated protein TIN2 localizes to both telomeres and mitochondria. Nevertheless, the impact of TIN2 on retinal pigment epithelial (RPE) cells in diabetic retinopathy (DR) remains unclear. This research aims to examine the role of TIN2 in the senescence of RPE and its potential as a therapeutic target. Western blotting and immunofluorescence staining were utilized to identify TIN2 expression and mitophagy. RT-qPCR was employed to identify senescent associated secretory phenotype (SASP) in ARPE-19 cells infected with TIN2 overexpression. To examine mitochondria and the cellular senescence of RPE, TEM, SA-ß-gal staining, and cell cycle analysis were used. The impact of TIN2 was examined using OCT and immunohistochemistry in mice. DHE staining and ZO-1 immunofluorescence were applied to detect RPE oxidative stress and tight junctions. Our research revealed that increased mitochondria-localized TIN2 aggravated the cellular senescence of RPE cells both in vivo and in vitro under hyperglycemia. TIN2 overexpression stimulated the mTOR signaling pathway in ARPE-19 cells and exacerbated the inhibition of mitophagy levels under high glucose, which can be remedied through the mTOR inhibitor, rapamycin. Knockdown of TIN2 significantly reduced senescence and mitochondrial oxidative stress in ARPE-19 cells under high glucose and restored retinal thickness and RPE cell tight junctions in DR mice. Our study indicates that increased mitochondria-localized TIN2 induced cellular senescence in RPE via compromised mitophagy and activated mTOR signaling. These results propose that targeting TIN2 could potentially serve as a therapeutic strategy in the treatment of DR.

UCP2-SIRT3 Signaling Relieved Hyperglycemia-Induced Oxidative Stress and Senescence in Diabetic Retinopathy.

Purpose: Diabetic retinopathy (DR) is one of the most common reasons for blindness. uncoupling protein 2 (UCP2), an uncoupling protein located in mitochondria, has been reported to be related to metabolic and vascular diseases. This research aimed to illustrate the function and mechanism of UCP2 in the pathogenesis of DR. Methods: Human epiretinal membranes were collected to investigate the expression of UCP2 by quantitative real-time polymerase chain reaction (qRT-PCR) and immunofluorescence. Primary human retinal microvascular endothelial cells (HRECs) were cultured in high glucose (HG) to establish an in vitro cell model for DR. Flow cytometry analysis was used to measure intracellular reactive oxygen species (ROS). Senescence levels were evaluated by the senescence-associated beta-galactosidase (SA-ß-gal) assay, the expression of senescence marker P21, and cell-cycle analysis. Adenovirus-mediated UCP2 overexpression or knockdown and specific inhibitors were administered to investigate the underlying regulatory mechanism. Results: Proliferative fibrovascular membranes from patients with DR illustrated the downregulation of UCP2 and sirtuin 3 (SIRT3) by qRT-PCR and immunofluorescence. Persistent hyperglycemia-induced UCP2 downregulation in the progress of DR and adenovirus-mediated UCP2 overexpression protected endothelial cells from hyperglycemia-induced oxidative stress and senescence. Under hyperglycemic conditions, UCP2 overexpression attenuated NAD+ downregulation; hence, it promoted the expression and activity of SIRT3, an NAD+-dependent deacetylase regulating mitochondrial function. 3-TYP, a selective SIRT3 inhibitor, abolished the UCP2-mediated protective effect against oxidative stress and senescence. Conclusions: UCP2 overexpression relieved oxidative stress and senescence based on a novel mechanism whereby UCP2 can regulate the NAD+-SIRT3 axis. Targeting oxidative stress and senescence amelioration, UCP2-SIRT3 signaling may serve as a method for the prevention and treatment of DR and other diabetic vascular diseases.

Enhancement of glycolysis-dependent DNA repair regulated by FOXO1 knockdown via PFKFB3 attenuates hyperglycemia-induced endothelial oxidative stress injury.

The accumulation of DNA damage induced by oxidative stress is a crucial pathogenic factor of endothelial loss in diabetic vascular complications, but it is still unknown whether aberrant glucose metabolism leads to defective DNA repair and accounts for hyperglycemia-induced endothelial oxidative stress injury. Here, we showed that Foxo1 knockdown alleviated diabetes-associated retinal DNA damage and vascular dysfunction. Mechanistically, FOXO1 knockdown avoided persistent DNA damage and cellular senescence under high glucose in endothelial cells by promoting DNA repair mediated by the MRN (MRE11-RAD50-NBS1 complex)-ATM pathway in response to oxidative stress injury. Moreover, FOXO1 knockdown mediated robust DNA repair by restoring glycolysis capacity under high glucose. During this process, the key glycolytic enzyme PFKFB3 was stimulated and, in addition to its promoting effect on glycolysis, directly participated in DNA repair. Under genotoxic stress, PFKFB3 relocated into oxidative stress-induced DNA damage sites and promoted DNA repair by interaction with the MRN-ATM pathway. Our study proposed that defective glycolysis-dependent DNA repair is present in diabetic endothelial cells and contributes to hyperglycemia-induced vascular dysfunction, which could provide novel therapeutic targets for diabetic vascular complications.

SYVN1 Promotes STAT3 Protein Ubiquitination and Exerts Antiangiogenesis Effects in Retinopathy of Prematurity Development.

Purpose: SYVN1, a gene involved in endoplasmic reticulum-associated degradation, has been found to exert a protective effect by inhibiting inflammation in retinopathy. This study aimed to clarify whether SYVN1 is involved in the pathogenesis of retinopathy of prematurity (ROP) and its potential as a candidate for target therapy. Methods: Human retinal microvascular endothelial cells (hRMECs) and a mouse model of oxygen-induced retinopathy (OIR) were used to reveal the retinopathy development-associated protein expression and molecular mechanism. An adenovirus overexpressing SYVN1 or vehicle control was injected intravitreally at postnatal day 12 (P12), and the neovascular lesions were evaluated in retinal flatmounts with immunofluorescence staining, and hematoxylin and eosin staining at P17. Visual function was assessed by using electroretinogram (ERG). Results: Endogenous SYVN1 expression dramatically decreased in hRMECs under hypoxia and in ROP mouse retinas. SYVN1 regulated the signal transducer and activator of transcription 3 (STAT3)/vascular endothelial growth factor (VEGF) axis. SYVN1 overexpression promoted ubiquitination and degradation of STAT3, decreased the levels of phospho-STAT3, secretion of VEGF, and formation of neovascularization in hRMECs, which could be rescued by STAT3 activator treatment. In addition, SYVN1 overexpression prevented neovascularization and extended physiologic retinal vascular development in the retinal tissues of OIR mice without affecting retinal function. Conclusions: SYVN1 has a protective effect against OIR, and the molecular mechanisms are partly through SYVN1-mediated ubiquitination of STAT3 and the subsequent downregulation of VEGF. These findings strongly support our assumption that SYVN1 confers ROP resistance and may be a potentially novel pharmaceutical target against proliferative retinopathy.

Can slide positivity rates predict malaria transmission?

BACKGROUND: Malaria is a significant threat to population health in the border areas of Yunnan Province, China. How to accurately measure malaria transmission is an important issue. This study aimed to examine the role of slide positivity rates (SPR) in malaria transmission in Mengla County, Yunnan Province, China. METHODS: Data on annual malaria cases, SPR and socio-economic factors for the period of 1993 to 2008 were obtained from the Center for Disease Control and Prevention (CDC) and the Bureau of Statistics, Mengla, China. Multiple linear regression models were conducted to evaluate the relationship between socio-ecologic factors and malaria incidence. RESULTS: The results show that SPR was significantly positively associated with the malaria incidence rates. The SPR (ß = 1.244, p = 0.000) alone and combination (SPR, ß = 1.326, p < 0.001) with other predictors can explain about 85% and 95% of variation in malaria transmission, respectively. Every 1% increase in SPR corresponded to an increase of 1.76/100,000 in malaria incidence rates. CONCLUSION: SPR is a strong predictor of malaria transmission, and can be used to improve the planning and implementation of malaria elimination programmes in Mengla and other similar locations. SPR might also be a useful indicator of malaria early warning systems in China.

Cost-effectiveness analysis of sugemalimab in combination with chemotherapy as first-line treatment in Chinese patients with metastatic NSCLC.

INTRODUCTION: Because of its low immunogenicity and associated risk of toxicity, sugemalimab is expected to reshape the first-line treatment landscape for non-small cell lung cancer (NSCLC) in China. However, it remains unclear whether the use of expensive sugemalimab is cost-effective in this population. METHODS: A Markov model was constructed based on the GEMSTONE-302 study to assess the efficacy of sugemalimab in combination with chemotherapy for first-line treatment of metastatic NSCLC. Efficacy and safety data were entered, with costs and utility values derived from the literature, and incremental cost-effectiveness ratios (ICERs) were estimated, and univariate sensitivity analyses and probabilistic sensitivity analyses were performed. We also considered cost-effectiveness in two different treatment regimen scenarios after disease progression. RESULTS: Compared with the placebo plus platinum-based chemotherapy, patients with metastatic NSCLC treated with sugemalimab plus platinum-based chemotherapy saw an increase of 0.56 life-years (LYs) and 0.41 quality-adjusted life-years (QALYs), and patients with squamous NSCLC resulted in an ICER per QALY of $45,280.02. Patients with nonsquamous metastatic NSCLC resulted in an ICER of $45,294.15 per QALY. Univariate sensitivity analysis showed that disease-free survival utility had the greatest impact on the results. Probabilistic sensitivity analysis (PSA) showed that when the willingness-to-pay (WTP) for QALYs was $27,354/QALY, sugemalimab, in combination with platinum-based chemotherapy, was more cost-effective than the placebo. CONCLUSION: From a Chinese health care system perspective, first-line treatment of squamous or nonsquamous metastatic NSCLC with sugemalimab plus platinum-based chemotherapy may have cost-effectiveness compared with placebo plus platinum-based chemotherapy at a WTP threshold of $27,354/QALY.

Secreted Protein Acidic and Rich in Cysteine Mediates the Development and Progression of Diabetic Retinopathy.

Backgrounds: Diabetic retinopathy (DR) is one of the most severe microvascular complications of diabetes mellitus (DM). Secreted protein acidic and rich in cysteine (SPARC) has been found to play an important role in many diseases, but its role and mechanism in DR remain unknown. Methods: We studied the role of SPARC and integrin ß1 in vascular pathophysiology and identified potential therapeutic translation. The SPARC levels were tested in human serum and vitreous by ELISA assay, and then the Gene Expression Omnibus (GEO) dataset was used to understand the key role of the target gene in DR. In human retinal capillary endothelial cells (HRCECs), we analyzed the mRNA and protein level by RT-PCR, immunohistochemistry, and Western blotting. The cell apoptosis, cell viability, and angiogenesis were analyzed by flow cytometry, CCK-8, and tube formation. Results: In this study, we investigated the role of SPARC in the development and progression of human DR and high glucose-induced HRCEC cells and found that the SPARC-ITGB1 signaling pathway mimics early molecular and advanced neurovascular pathophysiology complications of DR. The result revealed that DR patients have a high-level SPARC expression in serum and vitreous. Knockdown of SPARC could decrease the expressions of inflammatory factors and VEGFR, inhibit cell apoptosis and angiogenesis, and increase cell viability by regulating integrin ß1 in HRCECs. Conclusion: SPARC promotes diabetic retinopathy via the regulation of integrin ß1. The results of this study can provide a potential therapeutic application for the treatment of DR.

FBXW7 alleviates hyperglycemia-induced endothelial oxidative stress injury via ROS and PARP inhibition.

Diabetic retinopathy (DR) and other diabetic vascular complications are the leading cause of death and disability in patients with suboptimum glycemic control. In the pathogenesis of diabetic vascular diseases, hyperglycemia-induced oxidative stress, DNA damage, and poly-ADP-ribose-polymerase (PARP) hyperactivation play important roles in endothelial cell impairment. Adipose differentiation-related protein FBXW7 was reported to regulate PGC-1α stability and mitochondrial homeostasis. Here, we investigated the role and mechanism of FBXW7 in repairing endothelial oxidative stress injuries under hyperglycemic conditions. FBXW7 promoted the hampered activity of homologous recombination and non-homologues end joining pathway for repairing DNA double-strand breaks damage, an initiating factor for PARP hyperactivation and diabetic vascular complications. The abundant mobilization of DNA damage repair mediated by FBXW7 suppressed PARP activation, leading to downregulation of PARP expression and activity in both human endothelial cells and diabetic rat retinas. This provided a new method for PARP inhibition, superior to PARP inhibitors for treating diabetic vascular complication. Furthermore, FBXW7 rescued downregulated NAD+ levels and ameliorated mitochondrial dysfunction, thereby reducing superoxide production under hyperglycemic conditions. These effects reversed oxidative injury and vascular leakage in diabetic rat retina, providing a potential future treatment strategy.

C-CBL is required for inhibition of angiogenesis through modulating JAK2/STAT3 activity in ROP development.

PURPOSE: The incidence of retinopathy of prematurity (ROP) has increased continuously in recent years. However, the therapeutic effects of current treatments still remain undesired. This study aims to investigate the role of C-CBL in retinal angiogenesis in ROP and its potential as a therapeutic target. METHODS: Mouse retina microvascular endothelial cells (mRMECs) and induced experimental ROP/ oxygen-induced retinopathy (OIR) mice were employed to investigate the role of C-CBL in angiogenesis with combined molecular and cellular approaches, and histopathology methods. OIR mouse pups at postnatal day 12 (P12) were either injected intravitreally with adenovirus overexpressing c-Cbl or c-Cbl siRNA. Retinal neovascularization and avascular status were evaluated by retinal immunofluorescence (IF) staining, whole-mounts and hematoxylin and eosin (H&E) staining. RESULTS: C-CBL inhibits neovascularization by negatively regulating JAK2/STAT3/VEGF signaling axis in a ubiquitination-dependent manner. Knockdown of c-Cbl by siRNA reduced ubiquitin-mediated JAK2 degradation and increased levels of p-JAK2, p-STAT3, VEGF, and neovascularization in mRMECs, which can be reversed by JAK2 inhibitor treatment. While knockdown of c-Cbl significantly increased neovascular (NV) zone in the retinas, c-Cbl overexpression inhibited neovascularization in the retinal tissues in OIR mice. CONCLUSION: We found that C-CBL is required for anti-neovascularization process in ROP development by inhibiting JAK2/STAT3-dependent angiogenesis. Thus, our finding strongly suggest that C-CBL may be a potential novel therapeutic target for treating ROP.

Tolerance of Physocypria kraepelini (Crustacean, Ostracoda) to water-borne ammonia, phosphate and pH value.

This study evaluated the median lethal concentration (LC50) and safe concentration of water-borne ammonia, phosphate and pH value on Physocypria kraepelini, a freshwater Ostracoda with a static renewal test system. The results indicated that the LC50 values of ammonia for P kraepelini were 1026.71, 859.98, 771.79 and 583.82 mg/L at 24, 48, 72 and 96 h exposure, respectively, and the safe concentration range of ammonia for the long-term survival of P. kraepelini was less than 58.38 mg/L. The safe range of pH value for the survival of P. kraepelini was from 6.59 to 7.61. P. kraepelini has a high tolerance to ammonia, phosphate and pH value which are the main environmental factors in the serious eutrophication water.

Stable expression of antisense hTR inhibits in vitro pancreatic cancer cell growth.

OBJECTIVE: To clarify growth inhibition in pancreatic cancer cells by interference with the hTR component of the telomerase reverse transcriptase enzymatic complex. METHODS: A 593 bp full length hTR cDNA was subcloned into a mammalian expression vector pcDNA3.1(-) in the antisense orientation to construct an antisense hTR expression plasmid. These were introduced into panc1 cells, a human pancreatic carcinoma cell line, by lipofectin and G418-resistant stable transformants were expanded. Resulting stable clones were screened for the presence of the hTR insert by PCR with T7 and BGH reverse primers located on the flanks of the multiclonal site of the pcDNA3.1 vector. Cell growth rate, hTR expression, telomerase activity and anchorage-independent growth properties were analyzed. RESULTS: Significant downregulation of endogenous hTR was evident in the antisense-hTR transformed cells and telomerase activity was markedly decreased compared to control cells in standard TRAP assays. Furthermore, cell proliferation and the anchorage-independent growth ability in antisense-hTR expressing cells were significantly decreased compared with control parental cells. However, no crisis or senescence phenomena were observed. CONCLUSIONS: These data indicate that hTR may be a critical component of human telomerase activity and suggest that downregulation of the RNA component of human telomerase is a possible target for anticancer strategies.