Retinoblastoma ( Rb ) promotes senescence of corneal endothelial cells by inhibiting the activation of E2F2

Background Senescence-like changes occur in aging Corneal endothelial cells (CECs), and these changes are associated with decreased vision and age-related corneal diseases. such as Fuchs endothelial dystrophy (FED), chronic corneal allograft dysfunction (CCAD). Such changes have also been shown to cultured cell in vitro after passaging. Therefore, studying the mechanism of CEC senescence would aid in the development of anti-senescence treatment, which would benefit FED and CCAD. The tumor suppressor retinoblastoma (RB) gene product pRB triggers senescent growth arrest when inactivated. In this study, we used siRNA treatment to evaluate whether RB knockdown could suppress CEC senescence, and we investigated relevant molecular mechanisms.Methods RCECs were obtained and were cultured with or without siRb. Senescent cells were detected with a β-galactosidase senescence staining kit. The gene p21, which is associated with a senescent phenotype, was measured by RT-PCR. The morphology and migration of cultured RCECs were examined by phase-contrast microscopy. ZO-1 and N-Cadherin, which are involved in pump and barrier functions, were assessed by immunofluorescence. Cell cycle assessment was performed using a flow cytometer (BD FACSCalibur).Results As the cells were passaged, the number of senescent RCECs, the levels of the senescence-related gene p21, and the levels of senescence-associated secretory factors increased. SiRNA-mediated knockdown of RB led to suppression of cell senescence and the SASP. Furthermore, RB intervention increased the numbers of cells at the G2/M and S phase but did not influence the cell function or migratory ability. Knockdown of RB promoted the activation of E2F2.Conclusions We demonstrated that as the cells increased in passage number, the number of senescent RCECs, the levels of the senescence-related genes p21, and the levels of senescence-associated secretory factors increased. Retinoblastoma (Rb) promoted the senescence of corneal endothelial cells by inhibiting the activation of E2F2.

Tumor Milieu Controlled by RB Tumor Suppressor

The RB gene is one of the most frequently mutated genes in human cancers. Canonically, RB exerts its tumor suppressive activity through the regulation of the G1/S transition during cell cycle progression by modulating the activity of E2F transcription factors. However, aberration of the RB gene is most commonly detected in tumors when they gain more aggressive phenotypes, including metastatic activity or drug resistance, rather than accelerated proliferation. This implicates RB controls’ malignant progression to a considerable extent in a cell cycle-independent manner. In this review, we highlight the multifaceted functions of the RB protein in controlling tumor lineage plasticity, metabolism, and the tumor microenvironment (TME), with a focus on the mechanism whereby RB controls the TME. In brief, RB inactivation in several types of cancer cells enhances production of pro-inflammatory cytokines, including CCL2, through upregulation of mitochondrial reactive oxygen species (ROS) production. These factors not only accelerate the growth of cancer cells in a cell-autonomous manner, but also stimulate non-malignant cells in the TME to generate a pro-tumorigenic niche in a non-cell-autonomous manner. Here, we discuss the biological and pathological significance of the non-cell-autonomous functions of RB and attempt to predict their potential clinical relevance to cancer immunotherapy.

Evaluasi Resistensi dan Daya Hasil Enam Klon Harapan Kentang Transgenik Terhadap Serangan Penyakit Hawar Daun (Evaluation of Resistance to Late Blight and Tuber Yield of Six Potential Potato Transgenic Clones)

<p>Penyakit hawar daun (Phytophthora infestans) merupakan salah satu penyakit utama pada tanaman kentang. Kerusakan yang berat akibat penyakit hawar daun dapat menyebabkan kehilangan hasil panen sampai 80%. Gen pembawa ketahanan terhadap penyakit hawar daun dikenal dengan nama gen RB dan telah berhasil dimasukkan ke dalam genom kentang dan menghasilkan kentang transgenik. Tujuan penelitian untuk menguji ketahanan enam klon kentang transgenik terhadap serangan penyakit hawar daun (P. infestans) dan daya hasil. Penelitian dilakukan di Lapangan Uji Terbatas Desa Citere, Kecamatan Pangalengan, Kabupaten Bandung, 1.400 m di atas permukaan laut. Rancangan percobaan menggunakan rancangan petak terpisah, dengan petak utama perlakuan tidak disemprot fungisida dan disemprot fungisida dua kali seminggu dan anak petak 10 genotipe kentang yang terdiri atas enam hibrida kentang transgenik, satu genotipe kentang transgenik Katahdin SP951 sebagai pembanding resisten dan tiga varietas pembanding rentan kentang nontransgenik Granola, Atlantic, dan Katahdin. Jumlah ulangan tiga kali dengan populasi tanaman terdiri atas 50 tanaman/plot. Pengamatan dilakukan terhadap vigor tanaman, insiden serangan hawar daun, dan komponen hasil. Hasil pengamatan menunjukkan bahwa untuk vigor tanaman tidak terjadi interaksi serta antarperlakuan tidak berbeda nyata. Genotipe yang resisten terhadap hawar daun adalah klon 20, 27, 65, dan 66 setara dengan kontrol positif Katahdin SP951 dan nyata lebih resisten dari varietas pembanding Granola, Atlantic, dan Katahdin. Klon yang resisten terhadap hawar daun menampilkan hasil yang tinggi pada plot tidak disemprot fungisida, sementara pada plot disemprot fungisida 20 kali semua genotipe menampilkan hasil optimalnya. Tingkat kehilangan hasil mencapai 18,8–84,4%. Genotipe dengan intensitas serangan hawar daun tinggi memiliki tingkat kehilangan hasil yang juga tinggi. Klon 20 dan 27 menampilkan daya hasil yang relatif tinggi dengan penundaan penggunaan fungisida 7 minggu setelah tanam.</p><p><strong>Keywords</strong></p><p>Genotipe; <em>P. infestans; Solanum tuberosum</em> L</p><p><strong>Abstract</strong></p><p>Late blight (Phytophthora infestans) is one of main potato diseases. Due to severe damage to late blight potato, crop will be cause lost of harvest up to 80%. Gene carriers of resistance to late blight known as the RB gene and have been incorporate into the genom of potato and produce transgenic potato. The objective of the research was to test six advanced transgenic potato clones for resistance to late blight (Phytophthora infestans). The research was conducted at Confined Field Trial at Citere Village, Pangalengan District Bandung (1,400 m above sea level). The experimental design was split plot. The main plot was spray with fungicides twice/week and was replicated three times. Subplot were 10 potato genotypes, consists of six transgenic potato hybrids, transgenic Katahdin SP951 as resistant check and three varieties of nontransgenic as susceptible check, i.e. Granola, Atlantic, and Katahdin. An experimental unit consists of 50 plants/plot, every treatment with three replicates. Plant observed were plant vigor, intensity of late blight damage, tuber yield component, and lost of yield. The result showed that there were no interaction of plant vigor and also all the treatmens were not significantly different. Transgenic potato clones of 20, 27, 65, 66, and Katahdin SP951 were resistant to late blight compare to check varieties of Granola, Atlantic, and Katahdin. The highest yielding at none spraying of fungicides were obtained from the resistance clones. Whereas, on the 20 sprayed fungicides all of the clones were high yielding. Tuber yield lossed ranged from 18,8–84,4%, the susceptible genotypes were also showed high losses. Clones 20 and 27 showed reletive high yielding and can be delayed application fungicides for period of 7 weeks after planting. </p>