Biology subjects

Youssef, M. M. M.

Publications and source records attributed to Youssef, M. M. M..

3 recordsLinked to original sources

bioRxiv2024

Knockout of Dectin-1 does not modify disease onset or progression in a MATR3 S85C knock-in mouse model of ALS

Microglia have been increasingly implicated in neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). Dectin-1, encoded by the Clec7a gene, is highly upregulated in a specific microglial response state called disease-associated microglia (DAM) in various neurodegenerative conditions. However, the role of Dectin-1 in ALS is undetermined. Here, we show that Clec7a mRNA upregulation occurs in central nervous system (CNS) regions that exhibit neurodegeneration in a MATR3 S85C knock-in mouse model (Matr3S85C/S85C) of ALS. Furthermore, a significant increase in the number of Dectin-1+ microglia coincides with the onset of motor deficits, and this number increases with disease severity. We demonstrate that the knockout of Dectin-1 does not affect survival, motor function, neurodegeneration, or microglial responses in Matr3S85C/S85Cmice. These findings suggest that Dectin-1 does not play a role in modifying ALS onset or progression but could potentially serve as a valuable biomarker for ALS severity. Subject areasPhysiology; Molecular biology; Neuroscience; Immunology HighlightsO_LIClec7a upregulation is confined to central nervous system regions that exhibit overt neurodegeneration in a MATR3 S85C knock-in mouse model of ALS C_LIO_LIThe appearance of Dectin-1+ microglia coincides with the onset of motor deficits, and its number increases with disease progression C_LIO_LIKnockout of Dectin-1 does not modify survival, motor deficits, neurodegeneration, or microglial responses in MATR3 S85C knock-in mice C_LI

neuroscience↗

bioRxiv2022

TOB is an effector of the hippocampus-mediated acute stress response

Stress affects behavior and involves critical dynamic changes at multiple levels ranging from molecular pathways to neural circuits and behavior. Abnormalities at any of these levels lead to decreased stress resilience and pathological behavior. However, temporal modulation of molecular pathways underlying stress response remains poorly understood. Transducer of ErbB2.1, known as TOB, (TOB1) is involved in different physiological functions, including cellular stress and immediate response to stimulation. In this study, we investigated the role of TOB in the brains stress machinery at molecular, neural circuit, and behavioral levels. Interestingly, TOB protein levels increased after mice were exposed to acute stress. At the neural circuit level, functional magnetic resonance imaging (fMRI) suggested that intra-hippocampal and hippocampal-prefrontal connectivity were dysregulated in Tob knockout (Tob-KO) mice. Electrophysiological recordings in hippocampal slices showed increased postsynaptic AMPAR-mediated neurotransmission, accompanied by decreased GABA neurotransmission and subsequently altered Excitatory/Inhibitory balance after Tob deletion. At the behavioral level, Tob-KO mice show abnormal, hippocampus-dependent, contextual fear conditioning and extinction, and depression-like behaviors. On the other hand, increased anxiety observed in Tob-KO mice is hippocampus-independent. At the molecular level, we observed decreased stress-induced LCN2 expression and ERK phosphorylation, as well as increased MKP-1 expression. This study suggests that TOB serves as an important modulator in hippocampal stress signaling machinery. In summary, we show a molecular pathway and neural circuit mechanism by which TOB deletion contributes to expression of pathological stress-related behavior.

neuroscience↗

bioRxiv2021

Synaptotagmin 2 is ectopically overexpressed in excitatory presynapses of a widely used CaMK2a-Cre mouse line

The CaMKII-Cre mouse line, one of the earliest established Cre driver lines, has resulted in over 800 papers to date. Here, we demonstrate that the second most widely used CaMKII-Cre line, Tg(Camk2a-cre)2Gsc (or CamiCre), shows ectopic overexpression of synaptotagmin 2, the most efficient Ca2+ sensor for fast synchronous neurotransmitter release, in excitatory presynapses of Cre+ brains. Moreover, RNA-seq analysis showed aberrant expression in Cre+ hippocampus, including upregulation of immediate early genes, such as Arc and Fos, and genes presumably derived from bacterial artificial chromosome transgene, such as Slc6a7. Most importantly, CamiCre+ mice showed functional phenotypes, such as hyperactivity and enhanced associative learning, suggesting neural activities are affected. These unexpected results suggest difficulties in interpreting results from studies using the CamiCre line and raise awareness of potential pitfalls in the use of Cre driver lines in general.

genetics↗