👤 Atousa Bahrami

Phosphorylation of alpha-synuclein (αsyn) at serine 129 (PS129) marks aggregates in synucleinopathies but also occurs physiologically, potentially signaling protein interactions during neuronal activity. Technical barriers, including postmortem dephosphorylation, have hindered the study of physiological PS129 in the human brain. Using biotinylation by antibody recognition (BAR) on surgically resected temporal lobectomy tissues (without post-mortem interval), we mapped physiological PS129 and total αsyn interactomes. BAR identified 1,095 interactions with 513 αsyn-specific, 524 shared, and 58 PS129-specific, mostly associated with vesicles at presynaptic nerve terminals. PS129-specific interactions were uniquely associated with postsynaptic density proteins SHANK1/3, DLGAP1-4, DLGAP1-3, and DLG2-4, as well as nuclear-associated proteins HUWE1, HNRNPM, RBM14, ITCH, OGT, PHF24, and PPP2R5E. Fluorescent staining confirmed physiological PS129 proximal to dendrites and within the nucleus. Confirmation in healthy cynomolgus macaques (62% αsyn and 41% PS129 overlap) demonstrated that the interactomes were physiological rather than disease- or aggregate-associated. We conclude that physiological PS129 plays a unique and underappreciated role in postsynaptic neurons extending from the postsynaptic active zone to the nucleus. These interactomes benchmark normal αsyn biology, illuminating the transition to synucleinopathy pathology. Disease-associated αsyn phosphorylation (PS129) was recently identified in healthy mammalian brain and may signal αsyn-protein interactions during neuronal activity. Here, we surmounted technical hurdles and characterized αsyn and PS129 interactomes directly in the human brain. Results showed a unique significance for PS129 in post-synaptic active zones and nuclear compartments, which was confirmed in healthy non-human primates. These αsyn interactomes will be a valuable reference for understanding synucleinopathy mechanisms in the context of normal αsyn biology. Show less

Breast cancer (BC) is the most common cancer diagnosed in the world and it is also the main leading cause of cancer deaths in women. Change in epigenetic mechanisms promotes BC initiation and progression. Histone deacetylase 8 (HDAC8) was found to act as a potential oncogene in different malignancies. For better understanding of the HDAC8 function in BC development, we investigated the effect of HDAC8 deletion on the expression of genes involved in signaling pathways. In this study, CRISPR technology was used to knockout the HDAC8 gene in MDA-MB-468, MDA-MB-231 and MCF-7 ​cell lines. For this purpose, two gRNAs were designed and cloned into the PX459 vector. The gRNA-containing vectors were transfected into the BC cell lines and then the effect of this deletion on the expression of genes involved in signaling pathway was determined using quantitative real-time PCR (qRT-PCR). Analysis of qRT-PCR results showed a reduction in the expression of studied genes in BC cell lines after deletion of the HDAC8 gene compared to untreated controls. Although this decline was not significant for FGF2 and FGFR1 genes, however the mTOR, IGF1R, INSR, VEGFA and VEGFR2 genes showed statistically significant reduction in the studied BC cell lines. In addition, the down-regulation of PDGFC and PDGFRA genes were only significant in the TNBC cell lines. Overall, our study showed that HDAC8 can exert its oncogenic effects by altering the expression level of molecules involved in some signaling pathways, and inhibiting HDAC8 can revert these effects. Show less

The aim of this study was to evaluate the association of MC4R rs17782313 and FTO rs9939609 polymorphisms with childhood obesity. A universal search was performed up to May 2021. A total of 31 studies including 13 studies with 9565 cases and 11956 controls on MC4R rs17782313 and 18 studies with 4789 cases and 15918 controls on FTO rs9939609 were selected. Pooled data showed that FTO rs9930506 and MC4R rs17782313 polymorphisms were significantly associated with obesity in children. Stratified analyses revealed that these genetic variants were associated with childhood obesity in Caucasian and Asian children. Show less

Pediatric osteosarcoma is characterized by multiple somatic chromosomal lesions, including structural variations (SVs) and copy number alterations (CNAs). To define the landscape of somatic mutations in pediatric osteosarcoma, we performed whole-genome sequencing of DNA from 20 osteosarcoma tumor samples and matched normal tissue in a discovery cohort, as well as 14 samples in a validation cohort. Single-nucleotide variations (SNVs) exhibited a pattern of localized hypermutation called kataegis in 50% of the tumors. We identified p53 pathway lesions in all tumors in the discovery cohort, nine of which were translocations in the first intron of the TP53 gene. Beyond TP53, the RB1, ATRX, and DLG2 genes showed recurrent somatic alterations in 29%-53% of the tumors. These data highlight the power of whole-genome sequencing for identifying recurrent somatic alterations in cancer genomes that may be missed using other methods. Show less

To identify sepsis-related dysregulations of protein expression in the liver, we used a baboon model of acute endotoxemia and performed comparative proteome analysis. Treatment with lipopolysaccharide (LPS) was followed by an early but long-lasting (5-48 h) generation of N-terminal fragments of carbamoyl phosphate synthase-1 (CPS-1), an abundant enzyme of the hepatic urea cycle, which is normally located in the mitochondrial matrix. In addition, we developed a new sandwich immunoassay to determine circulating CPS-1 in human and baboons. We found CPS-1 to be induced by LPS and to be released into the circulation of healthy humans and baboons as early as 4 to 5 h after stimulation. Similarly, CPS-1 levels increased after injection of gram-positive bacteria in another baboon model. Enhanced CPS-1 levels were also detected in serum of patients with sepsis. Our data demonstrate fragmentation of CPS-1 in the liver and early increase in circulating CPS-1 levels under septic conditions. We suggest that circulating CPS-1 might serve as a novel serum marker indicating mitochondrial impairment of the liver and/or the small intestine in critically ill patients. Show less