RNA/DNA Binding Protein TDP43 Regulates DNA Mismatch Repair Genes with Implications for Genome Stability.

TDP43 is an RNA/DNA binding protein increasingly recognized for its role in neurodegenerative conditions including amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). As characterized by its aberrant nuclear export and cytoplasmic aggregation, TDP43 proteinopathy is a hallmark feature in over 95% of ALS/FTD cases, leading to the formation of detrimental cytosolic aggregates and a reduction in nuclear functionality within neurons. Building on our prior work linking TDP43 proteinopathy to the accumulation of DNA double-strand breaks (DSBs) in neurons, the present investigation uncovers a novel regulatory relationship between TDP43 and DNA mismatch repair (MMR) gene expressions. Here, we show that TDP43 depletion or overexpression directly affects the expression of key MMR genes. Alterations include MLH1, MSH2, MSH3, MSH6, and PMS2 levels across various primary cell lines, independent of their proliferative status. Our results specifically establish that TDP43 selectively influences the expression of MLH1 and MSH6 by influencing their alternative transcript splicing patterns and stability. We furthermore find aberrant MMR gene expression is linked to TDP43 proteinopathy in two distinct ALS mouse models and post-mortem brain and spinal cord tissues of ALS patients. Notably, MMR depletion resulted in the partial rescue of TDP43 proteinopathy-induced DNA damage and signaling. Moreover, bioinformatics analysis of the TCGA cancer database reveals significant associations between TDP43 expression, MMR gene expression, and mutational burden across multiple cancers. Collectively, our findings implicate TDP43 as a critical regulator of the MMR pathway and unveil its broad impact on the etiology of both neurodegenerative and neoplastic pathologies.

PAD2 dysregulation and aberrant protein citrullination feature prominently in reactive astrogliosis and myelin protein aggregation in sporadic ALS.

Alteration in protein citrullination (PC), a common posttranslational modification (PTM), contributes to pathogenesis in various inflammatory disorders. We previously reported that PC and protein arginine deiminase 2 (PAD2), the predominant enzyme isoform that catalyzes this PTM in the central nervous system (CNS), are altered in mouse models of amyotrophic lateral sclerosis (ALS). We now demonstrate that PAD2 expression and PC are altered in human postmortem ALS spinal cord and motor cortex compared to controls, increasing in astrocytes while trending lower in neurons. Furthermore, PC is enriched in protein aggregates that contain the myelin proteins PLP and MBP in ALS. These results confirm our findings in ALS mouse models and suggest that altered PAD2 and PC contribute to neurodegeneration in ALS.

Protein citrullination marks myelin protein aggregation and disease progression in mouse ALS models.

Increased protein citrullination (PC) and dysregulated protein arginine deiminase (PAD) activity have been observed in several neurodegenerative diseases. PC is a posttranslational modification catalyzed by the PADs. PC converts peptidyl-arginine to peptidyl-citrulline, thereby reducing the positive charges and altering structure and function of proteins. Of the five PADs, PAD2 is the dominant isoform in the central nervous system (CNS). Abnormal PC and PAD dysregulation are associated with numerous pathological conditions, including inflammatory diseases and neurodegeneration. Animal model studies have shown therapeutic efficacy from inhibition of PADs, thus suggesting a role of PC in pathogenesis. To determine whether PC contribute to amyotrophic lateral sclerosis (ALS), a deadly neurodegenerative disease characterized by loss of motor neurons, paralysis, and eventual death, we investigated alterations of PC and PAD2 in two different transgenic mouse models of ALS expressing human mutant SOD1G93A and PFN1C71G, respectively. PC and PAD2 expression are altered dynamically in the spinal cord during disease progression in both models. PC and PAD2 increase progressively in astrocytes with the development of reactive astrogliosis, while decreasing in neurons. Importantly, in the spinal cord white matter, PC accumulates in protein aggregates that contain the myelin proteins PLP and MBP. PC also accumulates progressively in insoluble protein fractions during disease progression. Finally, increased PC and PAD2 expression spatially correlate with areas of the CNS with the most severe motor neuron degeneration. These results suggest that altered PC is an integral part of the neurodegenerative process and potential biomarkers for disease progression in ALS. Moreover, increased PC may contribute to disease-associated processes such as myelin protein aggregation, myelin degeneration, and astrogliosis.

Exposure to prolonged unpredictable light impairs spatial memory via induction of oxidative stress and tumor necrosis factor-alpha in rats.

OBJECTIVES: The human body physiology rapidly changes and adapt to several environmental stimuli, including light. Abnormal artificial light exposures have been shown to affect sleep cycle, cognition, and mood. Although studies have reported inconsistent effects of short-term or constant long-term light exposures, human exposures to artificial lights occur at varying, unpredictable times and duration daily. Here, we studied the effects of long-term unpredictable light exposure on learning, memory, oxidative status, and associated cytokines in rats. METHODS: Artificial lighting was provided using an array of white light-emitting diodes coupled to a microcontroller that switches them on or off at unpredictable times and duration (light intensity = 200 ± 20 lx). Within the last eight days of 40 days exposure, animals were subjected to open field test, Morris water maze, and novel object recognition behavioral paradigms. Brain levels of malondialdehyde (MDA), superoxide dismutase (SOD), catalase, reduced glutathione (GSH), glutathione S-transferase (GST), tumor necrosis factor-alpha (TNF-α), and vascular endothelial growth factor (VEGF) were assayed. RESULTS: Exposed rats showed impaired spatial learning and memory (p<0.05), but no changes in object recognition memory or locomotor activity. Oxidative stress analyses also revealed significant changes in the concentrations of MDA, SOD, catalase, and GSH levels (p<0.05), not GST. Similarly, there was an increased TNF-α expression (p<0.05), not VEGF. CONCLUSIONS: We conclude that oxidative stress is involved in memory impairment in rats exposed to prolonged unpredictable lights, which again suggests the detrimental effects of extended light exposure on the nervous system.

Increasing the availability and quality of caesarean section in Tanzania.

OBJECTIVE: To describe the results of increasing availability and quality of caesarean deliveries and anaesthesia in rural Tanzania. DESIGN: Before-after intervention study design. SETTINGS: Rural Tanzania. METHODS: Ten health centres located in rural areas were upgraded to provide comprehensive emergency obstetric care (CEmOC) and the four related district hospitals were supported. Upgrading entailed constructing and equipping maternity blocks, operation rooms and laboratories; installing solar systems, backup generators and water supply systems. Associate clinicians were trained in anaesthesia and in CEmOC. Mentoring and audit of reasons for caesarean section (CS) and maternal deaths were carried out. Measures of interest were compared using analysis of variance (ANOVA) statistical tests. MAIN OUTCOME MEASURES: Trends in CS rates, proportion of unjustified CS, use of spinal anaesthesia, and the risk of death from complications related to CS and anaesthesia. RESULTS: During the audit period (2012-2014), 5868 of 58 751 deliveries were by CS (10%). The proportion of CS considered to be unjustified decreased from 30 to 17% in health centres (P = 0.02) and from 37 to 20% in hospitals (P < 0.001). Practice of spinal anaesthesia for CS increased from 10% to 64% in hospitals (P < 0.001). Of 110 maternal deaths, 18 (16.4%) were associated with complications of CS, giving a risk of 3.1 per 1000 CS; three (2.7%) were judged to be anaesthetic-associated deaths with a risk of 0.5 per 1000 caesarean deliveries. CONCLUSIONS: Increasing availability and quality of CS by improving infrastructure, training and audit of reasons for CS is feasible, acceptable and required in low resource settings. TWEETABLE ABSTRACT: Increasing availability and quality of CS in rural Africa is feasible.

The effects of a pre-season treatment with effective antimalarials on subsequent malaria morbidity in under five-year-old children living in high and seasonal malaria transmission area of Burkina Faso.

OBJECTIVES: To evaluate the effects of pre-season treatment with single dose of sulfadoxine-pyrimethamine (SP) or artemether-lumefantrine (AL) on subsequent malaria morbidity in under-fives. METHODS: A cohort of 156 children was enrolled for longitudinal follow-up. Children received curative therapy with SP or AL, and a third group received no treatment. Participants were home-visited twice a week with blood smears taken from children with fever (axillary T° ≥ 37.5 °C) or history of fever. To assess the time to re-infection, a blood film was also systematically obtained from pre-treated children every 2 weeks. RESULTS: The mean time to the first malaria infection was 36 days in the SP arm and 26 days in the AL arm (P=0.006). The incidence density of malaria infection was similar in both groups (86.5%vs. 92.3%, P=0.52). The mean time to the first malaria episode was 47 days in the SP arm and 32 days in the AL arm (P<0.001). The incidence of malaria episodes was significantly higher in the group pre-treated with AL (45.7 per 1000 child days-at-risk CI 95% [35-56]) than in the control group (10.7 per 1000 child days-at-risk CI 95% [7-15]); P<0.001). CONCLUSIONS: Our findings suggest that the radical clearance of parasitemia with AL may increase susceptibility to malaria infection and clinical malaria episodes.

Making a friend from a foe: expressing a GroEL gene from the whitefly Bemisia tabaci in the phloem of tomato plants confers resistance to tomato yellow leaf curl virus.

Some (perhaps all) plant viruses transmitted in a circulative manner by their insect vectors avoid destruction in the haemolymph by interacting with GroEL homologues, ensuring transmission. We have previously shown that the phloem-limited begomovirus tomato yellow leaf curl virus (TYLCV) interacts in vivo and in vitro with GroEL produced by the whitefly vector Bemisia tabaci. In this study, we have exploited this phenomenon to generate transgenic tomato plants expressing the whitefly GroEL in their phloem. We postulated that following inoculation, TYLCV particles will be trapped by GroEL in the plant phloem, thereby inhibiting virus replication and movement, thereby rendering the plants resistant. A whitefly GroEL gene was cloned in an Agrobacterium vector under the control of an Arabidopsis phloem-specific promoter, which was used to transform two tomato genotypes. During three consecutive generations, plants expressing GroEL exhibited mild or no disease symptoms upon whitefly-mediated inoculation of TYLCV. In vitro assays indicated that the sap of resistant plants contained GroEL-TYLCV complexes. Infected resistant plants served as virus source for whitefly-mediated transmission as effectively as infected non-transgenic tomato. Non-transgenic susceptible tomato plants grafted on resistant GroEL-transgenic scions remained susceptible, although GroEL translocated into the grafted plant and GroEL-TYLCV complexes were detected in the grafted tissues.

Small high density lipoprotein subclasses: some of their physico-chemical properties and stability in solution.

Small high density lipoproteins (SHDL) contribute to the protection from atherosclerosis, but detailed information about their properties is not available yet. We isolated four of the smallest HDL subclasses that contain apoA-I alone, the small lipoprotein A-I (SLpAI), by their separation on gradient polyacrylamide gel followed by electroelution. Their physico-chemical properties were calculated from their displacement in non-denaturing gradient polyacrylamide gel under the effect of electrical potential. The properties are: Stokes' radii 2.96-3.56 nm; molecular masses 42-70 kDa; net negative charge 7.2-13.5; surface charge densities 3139-4069 -esu.cm(-2); surface potentials 10.6-15.7 -mV; coefficients of friction 5.74-6.90 x 10(-8) g.s(-1); and diffusion coefficients 5.76-6.94 x 10(-7) cm(2).s(-1). We found that these particles were of low stability as they underwent molecular transformation into larger particles on storage. The estimated dimensions of these particles do not support ellipsoidal shape, therefore, the most probable shape is spherical; consequently, their hydrated characteristics were estimated. We conclude that these particles have high values of negative surface charge and diffusion coefficients, and are of low stability. Their small Stokes' radii were similar to each other and they are spherical and highly hydrated.

[Epidemiology and control of bacterial meningitis in children less than 1 year in Niamey (Niger)]. / Epidémiologie et contrôle des méningites bactériennes chez les enfants de moins d'un an à Niamey (Niger).

A bacteriological and epidemiological study of bacterial meningitis occurring in infants under one year of age was performed from September 1981 to June 1997 in Niamey, a city of 575,000 residents, located within the African meningitis belt. Cases of meningitis were defined either by culture of the cerebrospinal fluid (CSF), specific antigen agglutination, staining or cell counts of the CSF. Over the 16 years involving both epidemic and non epidemic periods, 1,481 infant's CSF were analysed, representing 20% out of the total CSF samples. The average of annual incidence rates was 511.4 cases per 100,000 infants under one year. Haemophilus influenzae b represented 35.1% of the cases, Streptococcus pneumoniae 26.3% and Neisseria meningitidis 17.6%. The other bacteria represented 5.5% and, for 15.5% out of the analysed CSF, the causative agent was not identified. The average annual mortality rate was 146.9 deaths for 100,000 infants under one year. The specific case fatality rates were 43% for H. influenzae b, 58.9% for S. pneumoniae and 17.8% for N. meningitidis. This study showed that in Niamey, as in the rest of the meningitis belt, S. pneumoniae and H. influenzae b were the main causes of bacterial meningitis occurring in infants under one year. However, the specific incidence of N1 meningitidis was identical for every age group between 0 and 20 years, and varied from 45 per 100,000 during non epidemic year to 550 per 100,000 during epidemic year. Immunisation with conjugate vaccines, particularly anti-Haemophilus vaccine appears to be the best preventive measure. The systematic use of ceftriaxone in infants, during meningococcal meningitis either epidemics or not, is highly recommended.