RecQ helicases, highly conserved proteins with pivotal roles in DNA replication, DNA repair and homologous recombination, are crucial for maintaining genomic integrity. Mutations in RECQL4 have been associated with various human diseases, including Rothmund–Thomson syndrome. RECQL4 is involved in regulating major DNA repair pathways, such as homologous recombination and nonhomologous end joining (NHEJ). RECQL4 has more prominent single-strand DNA annealing activity than helicase activity. Its ability to promote DNA damage repair and the precise role of its DNA annealing activity in DNA repair are unclear. Here we demonstrate that PARP1 interacts with RECQL4, increasing its single-stranded DNA strand annealing activity. PARP1 specifically promoted RECQL4 PARylation at both its N- and C-terminal regions, promoting RECQL4 recruitment to DNA double-strand breaks (DSBs). Inhibition or depletion of PARP1 significantly diminished RECQL4 recruitment and occupancy at specific DSB sites on chromosomes. After DNA damage, PARG dePARylated RECQL4 and stimulated its end-joining activity. RECQL4 actively displaced replication protein A from single-stranded DNA, promoting microhomology annealing in vitro. Furthermore, depletion of PARP1 or RECQL4 substantially impacted classical-NHEJ- and alternative-NHEJ-mediated DSB repair. Consequently, the combined activities of PARP1, PARG and RECQL4 modulate DNA repair. Cells have mechanisms to repair DNA damage, which is crucial for preventing diseases such as cancer. The authors wanted to understand how another protein, PARP1, affects the role of RECQL4 in DNA repair. The study involved laboratory experiments using human cells to see how RECQL4 and PARP1 interact. PARP1 helps recruit RECQL4 to sites of DNA damage and enhances its ability to repair DNA by promoting the strand annealing process. However, when RECQL4 is modified by PARP1 through PARylation, its repair activity is reduced. Another protein, PARG, can reverse this modification, restoring the function of RECQL4. The results suggest that the interaction between RECQL4 and PARP1 is important for efficient DNA repair. This understanding could lead to new strategies for treating diseases related to DNA repair defects, such as cancer. This summary was initially drafted using artificial intelligence, then revised and fact-checked by the author.

RecQ helicases, highly conserved proteins with pivotal roles in DNA replication, DNA repair, and homologous recombination, are crucial for maintaining genomic integrity. Mutations in RECQL4 have been associated with various human diseases, including Rothmund-Thomson syndrome. RECQL4 is involved in regulating major DNA repair pathways, such as homologous recombination (HR) and non-homologous end repair (NHEJ). RECQL4 has a more prominent single-strand DNA annealing activity than helicase activity. Its recruitment to DNA damage and the precise role of its DNA annealing activity in DNA repair is unclear. This study reveals that PARP1 interacts with RECQL4, enhancing its single-stranded DNA (ssDNA) strand annealing activity. PARP1 specifically promotes - RECQL4-PAR binding at both its N- and C-terminal regions, promoting RECQL4’s recruitment to DNA double-strand break (DSB). Inhibition or depletion of PARP1 significantly diminishes RECQL4 recruitment and occupancy at specific DSB sites on chromosomes. RECQL4 actively displaces replication protein A (RPA) from ssDNA, promoting microhomology annealing in vitro. Further, depletion of PARP1 or RECQL4 substantially impacts classical-NHEJ (c-NHEJ) and alternative-NHEJ (alt-NHEJ)-mediated DSB repair. Consequently, the combined activities of PARP1 and RECQL4 modulate DNA repair.

RecQ helicases, highly conserved proteins with pivotal roles in DNA replication, DNA repair, and homologous recombination, are crucial for maintaining genomic integrity. Mutations in RECQL4 have been associated with various human diseases, including Rothmund-Thomson syndrome. RECQL4 is involved in regulating major DNA repair pathways, such as homologous recombination (HR) and non-homologous end repair (NHEJ). RECQL4 has a more prominent single-strand DNA annealing activity than helicase activity. Its recruitment to DNA damage and the precise role of its DNA annealing activity in DNA repair is unclear. This study reveals that PARP1 interacts with RECQL4, enhancing its single-stranded DNA (ssDNA) strand annealing activity. PARP1 specifically promotes - RECQL4-PARylation at both its N- and C-terminal regions, promoting RECQL4’s recruitment to DNA double-strand break (DSB). Inhibition or depletion of PARP1 significantly diminishes RECQL4 recruitment and occupancy at specific DSB sites on chromosomes. RECQL4 actively displaces replication protein A (RPA) from ssDNA, promoting microhomology annealing in vitro. Further, depletion of PARP1 or RECQL4 substantially impacts classical-NHEJ (c-NHEJ) and alternative-NHEJ (alt-NHEJ)-mediated DSB repair. Consequently, the combined activities of PARP1 and RECQL4 modulate DNA repair.

Olfactory dysfunction is a prevalent symptom and an early marker of age-related neurodegenerative diseases in humans, including Alzheimer's and Parkinson's Diseases. However, as olfactory dysfunction is also a common symptom of normal aging, it is important to identify associated behavioral and mechanistic changes that underlie olfactory dysfunction in nonpathological aging. In the present study, we systematically investigated age-related behavioral changes in four specific domains of olfaction and the molecular basis in C57BL/6J mice. Our results showed that selective loss of odor discrimination was the earliest smelling behavioral change with aging, followed by a decline in odor sensitivity and detection while odor habituation remained in old mice. Compared to behavioral changes related with cognitive and motor functions, smelling loss was among the earliest biomarkers of aging. During aging, metabolites related with oxidative stress, osmolytes, and infection became dysregulated in the olfactory bulb, and G protein coupled receptor-related signaling was significantly down regulated in olfactory bulbs of aged mice. Poly ADP-ribosylation levels, protein expression of DNA damage markers, and inflammation increased significantly in the olfactory bulb of older mice. Lower NAD+ levels were also detected. Supplementation of NAD+ through NR in water improved longevity and partially enhanced olfaction in aged mice. Our studies provide mechanistic and biological insights into the olfaction decline during aging and highlight the role of NAD+ for preserving smelling function and general health.

Aging is accompanied by a decline in DNA repair efficiency, which leads to the accumulation of different types of DNA damage. Age-associated chronic inflammation and generation of reactive oxygen species exacerbate the aging process and age-related chronic disorders. These inflammatory processes establish conditions that favor accumulation of DNA base damage, especially 8-oxo-7,8 di-hydroguanine (8-oxoG), which in turn contributes to various age associated diseases. 8-oxoG is repaired by 8-oxoG glycosylase1 (OGG1) through the base excision repair (BER) pathway. OGG1 is present in both the cell nucleus and in mitochondria. Mitochondrial OGG1 has been implicated in mitochondrial DNA repair and increased mitochondrial function. Using transgenic mouse models and cell lines that have been engineered to have enhanced expression of mitochondria-targeted OGG1 (mtOGG1), we show that elevated levels of mtOGG1 in mitochondria can reverse aging-associated inflammation and improve functions. Old male mtOGG1Tg mice show decreased inflammation response, decreased TNFα levels and multiple pro-inflammatory cytokines. Moreover, we observe that male mtOGG1Tg mice show resistance to STING activation. Interestingly, female mtOGG1Tg mice did not respond to mtOGG1 overexpression. Further, HMC3 cells expressing mtOGG1 display decreased release of mtDNA into the cytoplasm after lipopolysacchride induction and regulate inflammation through the pSTING pathway. Also, increased mtOGG1 expression reduced LPS-induced loss of mitochondrial functions. These results suggest that mtOGG1 regulates age-associated inflammation by controlling release of mtDNA into the cytoplasm.

Alterations in olfactory functions are proposed to be early biomarkers for neurodegeneration. Many neurodegenerative diseases are age-related, including two of the most common, Parkinson's disease (PD) and Alzheimer's disease (AD). The establishment of biomarkers that promote early risk identification is critical for the implementation of early treatment to postpone or avert pathological development. Olfactory dysfunction (OD) is seen in 90% of early-stage PD patients and 85% of patients with early-stage AD, which makes it an attractive biomarker for early diagnosis of these diseases. Here, we systematically review widely applied smelling tests available for humans as well as olfaction assessments performed in some animal models and the relationships between OD and normal aging, PD, AD, and other conditions. The utility of OD as a biomarker for neurodegenerative disease diagnosis and future research directions are also discussed.

Testicular carcinoid tumours are very rare and account for less than 1% of all testicular neoplasms.1 These tumours may be classified into three distinct groups, most commonly (1) primary testicular carcinoid, (2) carcinoid differentiation within a mature teratoma, and (3) metastases from an extra-testicular source. Testicular carcinoid tumours do not follow the age category of men affected most commonly by germ cell tumours (20-40 years), cases have been reported ranging in age from ten to eighty-three years.2 Presentation of carcinoid tumours may be with self-detected testicular mass or testicular ache as with common testicular tumours, or uncommonly with carcinoid syndrome. We report a case of primary carcinoid tumour of the testis without features of carcinoid syndrome.

Biologically-based approaches to large-scale solar power generation promise low cost durable technologies that will exhibit the self-repairing capabilities of photosynthetic organisms1–3 (Basic Research Needs for Solar Energy Utilization, U.S. Department of Energy, Washington DC, 2005; J. Barber and B. Andersson, Trends Biochem. Sci., 1992, 17, 61; A. Huijser et al., J. Phys. Chem. C, 2007, 111, 11726). Most proposed approaches however utilize photosynthetic proteins extracted from organisms4–6 (S. A. Trammell et al., J. Phys. Chem. C, 2007, 111, 17122; R. Das et al., Nano Lett., 2004, 4, 1079; E. Greenbaum, Science, 1985, 230, 1375) and forgo the self-repair capabilities of organisms resulting in short-lived power generation. Beginning with two non-descript graphite electrodes and marine sediment and seawater, we report here a proof-of-concept demonstration of a self-assembling and self-repairing microbial photoelectrochemical solar cell that generates electricity from sunlight7 (S. A. Licht, Nature, 1987, 330, 148). Time records of voltage and current generated by this solar cell reveal a circadian rhythm consistent with a photosynthetic nature. This result supports the interpretation that the electrode reactions are catalyzed by self-maintaining biofilms spontaneously formed on each electrode surface, and that the electrode reactants are photosynthetically regenerated from the electrode products by a self-maintaining spontaneously formed photosynthetic consortium. Our finding suggests a strait-forward approach toward durable biologically-based solar power generation.

The novel insulin receptor substrate protein APS is highly expressed in insulin-sensitive tissues and plays an important role in insulin-mediated glucose uptake and GLUT4 translocation via the Cbl/CAP pathway. Tyrosine phosphorylation of APS leads to recruitment of c-Cbl and Crk, while overexpression of APS mutant inhibits GLUT4 translocation in response to insulin, but the regulation of APS expression in skeletal muscle has not been previously reported. L6 myoblasts were differentiated in 2% FBS and serum starved for 24h prior to stimulation for 24h with either insulin 1 microM (n=6), rosiglitazone 10 microM (n=6), resistin 500 nM (n=6) or the MAP kinase inhibitor PD098059 50 microM (n=6) for 30 min, followed by insulin 1 microM for 24h. Semi-quantitative real-time RT-PCR was used to determine the expression of APS mRNA relative to the control gene TF2D. APS expression was markedly upregulated by myoblast differentiation (0.55+/-0.08 versus 1.14+/-0.08, p=0.001), and this effect was augmented by addition of rosiglitazone 10 microM for 24h to the differentiated myotubes (1.50+/-0.09, p=0.025). Insulin caused a 3.1-fold decrease in APS mRNA expression (0.37+/-0.01 versus 1.14+/-0.08, p=0.001), an effect that was attenuated by the MAP kinase inhibitor PD098059 (0.80+/-0.03, p=0.001). Exposure to resistin produced a modest decrease (1.4-fold) in myotube expression of APS (0.8+/-0.09, p=0.025). In conclusion, this is the first study to show that exposure to insulin markedly reduces the expression of APS in skeletal muscle via a MAP kinase dependent pathway, whereas myocyte differentiation and rosiglitazone increase APS expression. Changes in APS expression may be important in the aetiology and therapeutic reversal of insulin resistance in skeletal muscle.

Protein kinase C (PKC)-β and other PKC isozymes have been implicated in the loss of endothelial barrier function in diabetic microangiopathy. The effects of a PKC-β-specific inhibitor, LY379196, on hyperpermeability responses to high-glucose, angiotensin II, α-thrombin and endothelin-1 were evaluated using an in vitro model of human pulmonary artery endothelial cell monolayers. LY379196 attenuated the increase in transendothelial albumin flux induced by glucose 40 mM (e.g. 411±160% [high-glucose] vs. 167+37% [high-glucose+LY379196], P<0.001) and angiotensin II 10 μM (e.g. 121±12% vs. 246±35%, P<0.01); endothelin-1 had no significant effect on monolayer permeability. LY379196 had no significant effect on the marked hyperpermeability response to α-thrombin 1 μM. Thus, two major pathways involved in vascular leakage in diabetic microangiopathy are amenable to therapeutic blockade by PKC-β inhibition.

Aims: The regulation of uncoupling protein‐3 (UCP‐3) expression in muscle remains unclear, specifically in relation to dietary and drug treatments. The present study evaluated the effects of oleic acid and rosiglitazone on UCP‐3 mRNA expression in differentiated L6 myotubes. Methods: L6 myocytes were cultured and differentiated prior to exposure to rosiglitazone 10 µmol/l, oleic acid 100 µmol/l, or the combination, for 24 h, prior to semiquantitative evaluation of UCP‐3 mRNA relative to GAPDH mRNA by RT‐PCR. Results: Exposure to oleic acid produced a significant increase in UCP‐3 mRNA (0.012 ± 0.007 vs. 0.0011 ± 0.0006 for untreated cells, relative to GAPDH mRNA, p < 0.001). Rosiglitazone alone had no effect on UCP‐3 expression and nor did the glitazone affect oleic‐acid‐induced upregulation of UCP‐3. Conclusions: In L6 myotubes, 24‐h exposure to oleic acid produced a 10‐fold increase in UCP‐3 mRNA expression, but rosiglitazone had no effect. Oleic‐acid‐induced upregulation of UCP‐3 was not affected (positively or negatively) by glitazone exposure.

BACKGROUND Increases in PKC-theta (the major isoenzymic form of PKC in skeletal muscle) protein and isozyme activity have been reported in skeletal muscle from patients with type 2 diabetes mellitus (T2DM) and dietary-induced rodent models of insulin resistance, but the underlying biochemical mechanism is unclear and muscle PKC-theta mRNA expression has not been previously reported in patients with T2DM or in relation to in-vivo measurements of insulin sensitivity. METHODS Diet-only treated patients with T2DM (n=7) and healthy nondiabetic controls (n=7) of similar BMI attended the clinical research unit on two occasions, 1 week apart, for a skeletal muscle biopsy 2 h after a 75-g oral glucose load and measurement of whole-body insulin sensitivity using the euglycaemic hyperinsulinaemic clamp. RESULTS Type 2 DM patients were insulin resistant (M-value 3.0 +/- 0.4 vs. 8.6 +/- 0.8 mg glucose kg(-1) min(-1)) with fasting hyperinsulinaemia (306 +/- 116 vs. 34 +/- 9 pmol L(-1), P<0.001) and hypertriglyceridaemia (3.6 +/- 0.7 vs. 1.3 +/- 0.3 mmol L(-1), P<0.01) relative to controls. Semi-quantitative RT-PCR showed that expression of PKC-theta mRNA (relative to GAPDH mRNA) was 6-fold higher in T2DM subjects (0.63 + 0.25% vs. 0.09 + 0.07%, P<0.001), whereas there was no difference in expression of PKC-alpha mRNA between the two groups. Expression of PKC-theta mRNA was inversely correlated with insulin sensitivity (M) and positively correlated with fasting serum insulin concentration (P<0.02). CONCLUSIONS This is the first clinical study of PKC-theta mRNA expression in human diabetic skeletal muscle. The results indicate that transcriptional up-regulation of PKC-theta may at least partly contribute to the increased muscle PKC-theta signalling in T2DM, and that PKC-theta mRNA may be inversely related to in-vivo insulin sensitivity.

Peripheral and pulmonary oedema has emerged as the most common drug-related side effect of rosiglitazone in clinical practice, but the underlying mechanisms are not clear. Fluid retention and changes in vascular tone could contribute to oedema formation, but the interpretation of clinical and in vivo studies is particularly difficult and the direct effects of thiazolidinediones on endothelial barrier function have not been previously reported.

Protein kinase C (PKC) is a family of multifunctional isozymes that plays an important role in the regulation of intracellular insulin signal transduction in various insulin-sensitive tissues. This article highlights current understanding on the mechanism of PKC-induced insulin resistance in skeletal muscle, a major target site for insulin-mediated glucose disposal. Initial, apparently contradictory findings on the role of PKC on insulin action can be explained on the basis that certain PKC isoforms (e.g., -zeta and -lambda) have been identified as downstream targets of PI3-kinase activation, while DAG-sensitive PKCs (e.g., -theta and -epsilon) have negative regulatory effects on insulin signaling. Hence, pharmacological therapies targeting specific PKC isoforms could enhance insulin action and improve glycemic control in patients with impaired glucose tolerance and overt diabetes.

We previously reported that proinflammatory mediator bradykinin (BK) induces cyclooxygenase (COX)-2 expression in human airway smooth muscle (HASM), but the mechanism is unknown in any biological system. Here, we studied the role of specific protein kinase C (PKC) isozyme(s) in COX-2 expression. Among the eight PKC isozymes present in HASM cells, the Ca2+-independent PKC-delta and -epsilon and the Ca2+-dependent PKC-alpha and -betaI were translocated to the nucleus upon BK stimulation. BK-induced COX-2 expression and prostaglandin E2 (PGE2) accumulation were mimicked by the direct PKC activator phorbol 12-myristate 13-acetate (PMA) and inhibited by the broad spectrum PKC inhibitor bisindolylmaleimide I. However, the selective Ca2+-dependent PKC isozyme inhibitor Go 6976 had no effect. Furthermore, the membrane-permeable calcium chelator BAPTA-AM had no effect on BK-induced COX-2 expression and COX activity despite its inhibition of PGE2 accumulation, suggesting the involvement of Ca2+-independent PKC isozymes. Rottlerin, a PKC-delta inhibitor, also had no effect, likely implicating PKC-epsilon. BK-stimulated transcriptional activation of a COX-2 promoter reporter construct was enhanced by overexpression of wild-type PKC-epsilon and abolished by a dominant negative PKC-epsilon, but it was not affected by wild-type or dominant negative PKC-alpha or -delta. Collectively, our results demonstrate that PKC-e mediates BK-induced COX-2 expression in HASM cells.

The insulinotropic agent, exendin-4, is a long-acting analogue of glucagon-like peptide-1 (GLP-1) which improves glucose tolerance in humans and animals with diabetes, but the underlying mechanisms and the effects of exendin-4 on peripheral (muscle/fat) insulin action are unclear. Previous in vivo and clinical studies have been difficult to interpret because of complex, simultaneous changes in insulin and glucagon levels and possible effects on hepatic metabolism. Thus, the comparative effects of exendin-4 and GLP-1 on insulin-stimulated 2-[3H]deoxyglucose (2-DOG) uptake were measured in fully differentiated L6 myotubes and 3T3-adipocytes, including co-incubation with inhibitors of the PI-3-kinase (wortmannin) and mitogen-activated protein (MAP) kinase (PD098059) pathways. In L6 myotubes, there was a concentration-dependent and PI-3-kinase-dependent increase in insulin-stimulated 2-DOG uptake with exendin-4 and GLP-1, e.g. for exendin-4 the C(I-200) value (concentration of insulin required to increase 2-DOG uptake 2-fold) decreased from 1.3 +/- 1.4 x 10(-7)M (insulin alone, n=16) to 5.9 +/- 1.3 x 10(-8)M (insulin+exendin-4 0.1nM, n=18, P<0.03). A similar insulin-sensitizing effect was observed with exendin-4 in 3T3-adipocytes, but GLP-1 had no effect on adipocyte insulin sensitivity. In conclusion, this is the first direct evidence showing that exendin-4 increases insulin-stimulated glucose uptake in muscle and fat derived cells via a pathway that involves PI-3-kinase activation. Furthermore, the contrasting responses of exendin and GLP-1 in 3T3-adipocytes suggest that the peripheral insulin-sensitizing effect of exendin-4 (in contrast to the insulinotropic effect) does not involve the GLP-1 receptor pathway.

OBJECTIVES:the tissue renin-angiotensin system (RAS), which plays an important role in vascular structure and function, is regulated in part by an insertion-deletion polymorphism of the angiotensin converting enzyme (ACE) gene. We hypothesised that ACE genotype might affect rate of AAA expansion via modulating long-term structural changes associated with RAS activation.METHODS:fifty-eight patients (50 M, mean age 70 years, mean initial aneurysm size 4.3 cm) with current or previous AAA and serial (>3) annual ultrasound measurements of antero-posterior AAA size provided a sample of leucocyte DNA for ACE genotyping. AAA expansion rate (cm per year) for individual subjects was calculated by linear regression.RESULTS:median AAA expansion rate was 0.28 cm/year (range 0-1.8 cm/year), and the genotype distribution included DD (n=14), DI (n=29) and II (n=15). Corresponding median AAA expansion rates for each of the three genetic subgroups were 0.22, 0.32 and 0.30 cm/year, respectively (p=0.6, nonparametric).CONCLUSIONS:the wide inter-individual variability in AAA expansion rate is likely to reflect complex genetic and environmental interactions, but the lack of any relationship with ACE genotype suggests that differences in vascular ACE activity in aortic tissue are not major determinants of the variability in rate of AAA dilatation.