Pb exposure reduces the expression of SNX6 and Homer1 in offspring rats and PC12 cells

Comparative Study of Time-Dependent Aluminum Exposure and Post-Exposure Recovery Shows Better Improvement in Synaptic Changes and Neuronal Pathology in Rat Brain After Short-Term Exposure

Aluminum is a ubiquitous metal that causes multiple brain pathologies such as, cognitive dysfunction and Alzheimer's disease like symptoms. Exposure to aluminum through drinking water is responsible for hampering learning and memory. This study aimed to compare (1) the time-dependent effect of aluminum exposure (keeping total exposure of 5850 mg/kg same) in two durations, 30 and 45 days, and (2) to compare post-exposure self-recovery effect after 20 days in both (30 and 45 days exposure) groups. Rats were given 130 and 195 mg/kg of AlCl₃·6H₂O for 45 and 30 days respectively, to see the time-dependent exposure effect. At the end of exposure, rats were given distilled water and allowed to self-recover for 20 days to study the recovery. Expression levels of synaptic genes (Syp, SNAP25, Nrxn1/2, PSD95, Shank1/2, Homer1, CamkIV, Nrg1/2 and Kalrn) were measured using qPCR and compared in the exposure and recovery groups. Cellular morphology of the rat brain cortex and hippocampus was also investigated. Damage in lipid and protein profile was measured by employing FTIR. Results showed downregulation of mRNA expression of synaptic genes, plaques deposition, disorganization in lipid and protein profile by increasing membrane fluidity, and disorder and alteration of protein secondary structure after both exposure periods. However, better improvement/recovery in these parameters were observed in recovery group of 30 days aluminum exposure compared to 45 days aluminum exposure group. Taken together, these results suggested that short-term exposure resulted in better restoration of lipid and protein profile after time-dependent exposure of aluminum than prolonged exposure.

Mechanism of autophagy mediated by IGF-1 signaling pathway in the neurotoxicity of lead in pubertal rats

Lead can damage neuron synapses in the hippocampus and cause synaptic plasticity losses, and learning, memory, and intelligence impairments. Previous studies have focused on the functional and structural plasticity of hippocampal synapses; however, the specific molecular mechanisms behind such impairments are not fully understood. This study aimed to elucidate the molecular mechanisms of cognitive impairment in rats following chronic lead exposure and mitigate or prevent lead toxicity in the central nervous system. We found that lead exposure caused significant damage to rat nervous systems, that is, compared with the control group, the lead treatment group had more autophagosomes in their hippocampal neurons; lower serum and hippocampal IGF-1 levels; lower hippocampal IGF-1, IGF-1R, PI3K, Akt, and mTOR gene expression; and upregulated hippocampal autophagy-associated proteins levels. Brain stereotactic technology was used to conduct autophagy inhibitor in vivo intervention experiments, and the results of these experiments suggest that the autophagy inhibitor DC661 inhibited lead-exposure-induced autophagy and autophagy-related gene expression in the rat hippocampus, possibly through activation of the IGF-1 pathway. Overall, our findings suggest that lead might activate hippocampal autophagy through the IGF-1/PI3K/Akt/mTOR signaling pathway. Therefore, this study provides a novel molecular mechanism underlying developmental toxicity in pubertal rats induced by lead exposure and provides a new target for anticipation and reversal of such neurotoxicity.

Polyethyleneimine-Functionalized Carbon Nanotube/Graphene Oxide Composite: A Novel Sensing Platform for Pb(II) Acetate in Aqueous Solution

Heavy metal pollution is posing a severe health risk on living organisms. Therefore, significant research efforts are focused on their detection. Here, we developed a sensing platform sensor for the selective detection of lead(II) acetate. The sensor is based on self-assembled polyethyleneimine-functionalized carbon nanotubes (PEI-CNTs) and graphene oxide films deposited onto gold interdigitated electrodes. The graphene-based nanostructure showed a resistive behavior, and the fabricated layer-by-layer film was used to detect Pb(II) acetate in an aqueous solution by comparison of three electrochemical methods: impedance spectroscopy, amperometry, and potentiometry stripping analysis. The results obtained from different methods show that the detection limit was down to 36 pmol/L and the sensitivity up to 4.3 μAL/μmol, with excellent repeatability. The detection mechanism was associated with the high affinity of heavy metal ions with the functional groups present in the PEI-CNTs and GO, allowing high performance and sensitivity. The achieved results are important for the research toward integrated monitoring and sensing platforms for Pb(II) contamination in drinking water.

Homer1 is a Potential Biomarker for Prognosis in Human Colorectal Carcinoma, Possibly in Association with G3BP1 Signaling

Background

Homer scaffolding protein 1 (Homer1) is a postsynaptic scaffold protein that regulates the structure and function of excitatory synaptic as well as its intracellular signal transduction. However, the role of Homer1 in colorectal cancer as well as the underlying molecular mechanisms has not been elucidated.

Materials and Methods

To evaluate the alternations of gene expression during colorectal cancer, Homer1 expression was analyzed using the gene expression profiling interactive analysis and Oncomine analyses. The prognostic value of Homer1 expression was validated by our own colorectal cancer specimens using RT-PCR. Then, the cell viability, migration and invasion of colorectal cancer cell lines were detected by CCK-8 and transwell assay.

Results

We obtained the following important results. (1) Homer1 expression was significantly higher in colorectal cancer than normal samples. (2) Among patients with colorectal cancer, those with higher Homer1 expression had a lower survival rate. (3) The major mutation type of Homer1 in colorectal cancer samples was missense mutation. (4) Homer1 was able to promote colorectal cancer cell proliferation, migration, and invasion through up-regulating G3BP1 in vitro.

Conclusion

Our findings suggest that Homer1 may play a role in malignancy of colorectal cancer mainly through the G3BP1 signaling pathway, which might be a potential indicator of poor prognosis.