MERIT40 cooperates with BRCA2 to resolve DNA interstrand cross-links

MERIT40 is an essential component of the RAP80 ubiquitin recognition complex that targets BRCA1 to DNA damage sites. Although this complex is required for BRCA1 foci formation, its physiologic role in DNA repair has remained enigmatic, as has its relationship to canonical DNA repair mechanisms. Surprisingly, we found that Merit40^−/− mice displayed marked hypersensitivity to DNA interstrand cross-links (ICLs) but not whole-body irradiation. MERIT40 was rapidly recruited to ICL lesions prior to FANCD2, and Merit40-null cells exhibited delayed ICL unhooking coupled with reduced end resection and homologous recombination at ICL damage. Interestingly, Merit40 mutation exacerbated ICL-induced chromosome instability in the context of concomitant Brca2 deficiency but not in conjunction with Fancd2 mutation. These findings implicate MERIT40 in the earliest stages of ICL repair and define specific functional interactions between RAP80 complex-dependent ubiquitin recognition and the Fanconi anemia (FA)–BRCA ICL repair network.     

Anticancer activity of fungal taxol derived from Botryodiplodia theobromae Pat., an endophytic fungus,against 7, 12 dimethyl benz(a)anthracene (DMBA)-induced mammary gland carcinogenesis in Sprague dawley rats

Breast cancer is the second most prevalent cancer worldwide and their incidence increases gradually. Taxol (paclitaxel), a potent anticancer drug, is naturally isolated from the bark of the Pacific yew. Taxol is widely used in the treatment of ovarian, lung and breast cancer. The increased demand for taxol, coupled with its limited availability from the protected Pacific yew, has had researchers scrambling for alternate sources. The purpose of the present study is to investigate chemopreventive effect of fungal taxol derived from a novel endophytic fungus Botryodiplodia theobromae Pat., isolated from a medicinal plant Morinda citrifolia Linn. The fungal taxol is found to be active against the 7, 12 dimethyl benz(a)anthracene (DMBA)-induced mammary gland carcinogenesis in Sprague dawley rats. The enzymic and non-enzymic antioxidants i.e. superoxide dismutase (SOD), catalase (CAT), glutatione peroxidase (GPx), glutatione-S-transferase (GST), reduced glutathione (GSH), vitamin C and vitamin E were evaluated in control and experimental groups. Lipid peroxides levels (LPO) were also tested. Histological analysis of breast tissue was analyzed by haematoxylin and eosin staining to assess the cytoprotective role of fungal taxol active against breast cancer. Immunohistochemical analyses were also performed to evaluate the effect of fungal taxol on the inflammatory marker such as Cyclooxygenase-2 (COX-2) in control and experimental groups. The results showed that the fungal taxol significantly suppresses the DMBA-induced breast cancer in Sprague dawley rats.     

Renal adenocarcinoma presenting as a groin swelling: a case report

Renal cell carcinoma (RCC) is known to have myriad presentations due to the extremely vascular nature of the organ. RCC are known to metastasize extensively to various organs of the body. We report a case of a 70-years-old male who presented with multiple inguinal lymph node enlargements which on excision biopsy showed metastatic adenocarcinomatous deposit. Search for the primary revealed a RCC arising from the left kidney. Inguinal lymph nodal metastasis, an uncommon site of distant metastasis in renal neoplasm, as a fi rst clinical sign leading to the diagnosis is not yet reported in literature.     

Qualitative assessment of published studies on pulpotomy medicaments for primary molar teeth

The aim of the present study was to perform a qualitative assessment of published clinical studies, using the Medline database between 2006 and 2016, on commonly used pulpotomy medicaments. Standardized criteria proposed by Fuks and Papagiannoulis in 2006 was used by three independent examiners who assessed a total of 64 studies and graded the papers as grades A (38‐42), B1 (32‐37), B2 (25‐31), or C (<25) based on the score obtained. Dropout rates were calculated based on the initial sample and the final sample used for analysis. Only three papers were grade A, two of which were parts of the same clinical study with results presented at 24 and 42 months, respectively. Twelve papers were graded B1, 19 were graded B2, and 30 were graded C. The quality of evidence seemed greatest for formocresol (2 grade A, 21 grade B), followed by electro surgery (1 grade A study), calcium hydroxide (11 grade B studies), and ferric sulfate (11 grade B studies). The current qualitative assessment clearly highlights the inadequacies in the published studies, especially the study design and clinical and radiographic criteria, thus provides a basis for formulating specific guidelines for researchers embarking on conducting clinical trials on pulpotomy medicaments.     

Successful timely minimally invasive management of grade 4 renal injury in children: a report of two cases

Expectant management of renal injuries has become the standard of care but most of such experience has been with adult patients. Although some recent reports suggest equally comparable results in pediatric populations too, there is a paucity of data. We report our experience with two children who sustained grade 4 renal injury due to blunt trauma, which was managed successfully by endourological intervention facilitating preservation of renal units and review the current literature.     

Ocimum sanctum Linn. (Holy Basil) ethanolic leaf extract protects against 7,12-dimethylbenz(a)anthracene-induced genotoxicity, oxidative stress, and imbalance in xenobiotic-metabolizing enzymes

The present study was designed to evaluate the protective effects of ethanolic Ocimum sanctum leaf extract against 7,12-dimethylbenz[a]anthracene (DMBA)-induced genotoxicity, oxidative stress, and imbalance in xenobiotic-metabolizing enzymes. Four different concentrations of ethanolic O. sanctum leaf extract (100, 200, 300, and 400 mg/kg of body weight) were administered to Wistar rats by intragastric intubation for five consecutive days followed by intraperitoneal injection of DMBA (35 mg/kg of body weight) 90 minutes after the final dose of the extract. Administration of DMBA increased bone marrow micronuclei, phase I enzymes, lipid peroxidation, and protein carbonyl formation. This was accompanied by a significant decrease in the activities of phase II detoxification enzymes and antioxidants in the liver, erythrocytes, and bone marrow. Pretreatment with ethanolic O. sanctum leaf extract at a concentration of 300 mg/kg of body weight significantly reduced micronuclei formation and phase I enzymes as well as lipid and protein oxidation with enhanced antioxidant and phase II enzyme activities. The results of the present study suggest that ethanolic O. sanctum leaf extract inhibits DMBA-induced genotoxicity and oxidative stress by modulating xenobiotic-metabolizing enzymes, reducing the extent of lipid and protein oxidation and up-regulating antioxidant defenses.     

Lysophosphatidic acid receptors 1 and 2 play roles in regulation of vascular injury responses but not blood pressure

Phenotypic modulation of vascular smooth muscle cells (SMCs) is essential for the development of intimal hyperplasia. Lysophosphatidic acid (LPA) is a serum component that can promote phenotypic modulation of cultured SMCs, but an endogenous role for this bioactive lipid as a regulator of SMC function in vivo has not been established. Ligation injury of the carotid artery in mice increased levels in the vessel of both autotaxin, the lysophospholipase D enzyme responsible for generation of extracellular LPA, and 2 LPA responsive G protein-coupled receptors 1 (LPA1) and 2 (LPA2). LPA1(-/-)2(-/-) mice were partially protected from the development of injury-induced neointimal hyperplasia, whereas LPA1(-/-) mice developed larger neointimal lesions after injury. Growth in serum, LPA-induced extracellular signal-regulated protein kinase activation, and migration to LPA and serum were all attenuated in SMCs isolated from LPA1(-/-)2(-/-) mice. In contrast, LPA1(-/-) SMCs exhibited enhanced migration resulting from an upregulation of LPA3. However, despite their involvement in intimal hyperplasia, neither LPA1 nor LPA2 was required for dedifferentiation of SMCs following vascular injury or dedifferentiation of isolated SMCs in response to LPA or serum in vitro. Similarly, neither LPA1 nor LPA2 was required for LPA to elicit a transient increase in blood pressure following intravenous administration of LPA to mice. These results identify a role for LPA1 and LPA2 in regulating SMC migratory responses in the context of vascular injury but suggest that additional LPA receptor subtypes are required for other LPA-mediated effects in the vasculature.     

Ribosome–SRP–FtsY cotranslational targeting complex in the closed state

The signal recognition particle (SRP)-dependent pathway is essential for correct targeting of proteins to the membrane and subsequent insertion in the membrane or secretion. In Escherichia coli, the SRP and its receptor FtsY bind to ribosome–nascent chain complexes with signal sequences and undergo a series of distinct conformational changes, which ensures accurate timing and fidelity of protein targeting. Initial recruitment of the SRP receptor FtsY to the SRP–RNC complex results in GTP-independent binding of the SRP–FtsY GTPases at the SRP RNA tetraloop. In the presence of GTP, a closed state is adopted by the SRP–FtsY complex. The cryo-EM structure of the closed state reveals an ordered SRP RNA and SRP M domain with a signal sequence-bound. Van der Waals interactions between the finger loop and ribosomal protein L24 lead to a constricted signal sequence-binding pocket possibly preventing premature release of the signal sequence. Conserved M-domain residues contact ribosomal RNA helices 24 and 59. The SRP–FtsY GTPases are detached from the RNA tetraloop and flexible, thus liberating the ribosomal exit site for binding of the translocation machinery.The Escherichia coli signal recognition particle (SRP) is a complex consisting of the universally conserved protein Ffh and 4.5S RNA, which adopts a hairpin structure (1). Ffh is composed of the N-terminal domain, the G domain that harbors GTPase activity, and the C-terminal methionine-rich M domain that interacts with 4.5S RNA (2, 3) and with the signal sequence (4, 5). The N and G domains form a compact structural and functional unit termed “the NG domain.” Targeting of ribosome-nascent chain complexes (RNC) containing a signal sequence depends on the interaction of the RNC–SRP complex with the SRP receptor FtsY, which is membrane associated (6–9). FtsY and Ffh interact via their homologous NG domains and form a composite GTPase active site (10, 11). Crystal structures of the M domain reveal a hydrophobic groove used to capture signal sequences (4, 5, 12).Protein targeting is driven by highly regulated conformational rearrangements of SRP and FtsY as well as GTP hydrolysis. SRP recognizes and tightly binds to RNCs displaying a signal sequence (cargo). Next, RNC-bound SRP efficiently recruits FtsY to form a nucleotide-independent, transient early state that rearranges to a GTP-stabilized closed state (13). Ultimately, in the activated state, handover of the RNC to the Sec translocon takes place, followed by GTP hydrolysis and disassembly of the SRP–FtsY complex (14–16). These distinct conformational transitions are regulated by the ribosome and translocon in the membrane, leading to a switch from cargo recognition by SRP to cargo release (17, 18).Cryo-EM structures of bacterial SRP-bound RNCs revealed a tight cargo-recognition complex (19, 20). In the SRP–FtsY early complex an overall detachment of SRP from the ribosome was observed (21). In this state, the G domain of FtsY contacts the conserved SRP RNA tetraloop, and Ffh and FtsY interact via their N domains (21) forming a pseudosymmetric V-shaped complex positioned above the ribosomal tunnel exit. The active sites of the GTPase domains are apart from each other, explaining why the early state is inactive in GTP hydrolysis (13, 21, 22).GTP is required for SRP and FtsY to rearrange into the closed state. FRET experiments indicate that, in this state, the Ffh–FtsY NG domains adopt a conformation that resembles the intimate heterodimeric architecture observed in crystal structures (10, 11, 13). The complete SRP was crystallized in complex with the FtsY NG domain in the closed/activated state showing the NG domains docked at the distal end of the RNA hairpin (23, 24). Single-molecule total internal reflection fluorescence microscopy directly demonstrated that the Ffh–FtsY NG domains need to relocate from the tetraloop to the RNA distal end to become activated for GTP hydrolysis and to progress further in the targeting reaction (24).Although the early, closed, and activated SRP–FtsY targeting complexes have been well-characterized biochemically, the generation of distinct, conformationally homogenous closed and activated ribosome–SRP–FtsY complexes for structural studies proved to be exceedingly difficult, because the ribosome stabilizes the early state (13). We overcame this challenge by developing a robust complex preparation strategy, and describe here the cryo-EM structure of the closed state of the RNC–SRP–FtsY complex at a resolution of 5.7 Å.     

Nature nominee quercetin's anti‐influenza combat strategy—Demonstrations and remonstrations

Nature's providences are rather the choicest remedies for human health and welfare. One such is quercetin, which is nature's nominee for cancer cure and recently demonstrated against influenza attack. Quercetin is highly recognized for its anticancer applications. This review emphasizes on yet another gift that this compound has to offer for mankind, which is none other than combating the deadly evasive influenza virus. The chemistry of this natural bioflavonoid and its derivatives and its modus operandi against influenza virus is consolidated into this review. The advancements and achievements made in the anti‐influenza clinical history are also documented. Further, the challenges facing the progress of this compound to emerge as a predominant anti‐influenza drug are discussed, and the future perspective for breaking its limitations through integration with nanoplatforms is envisioned.