Biology subjects

Ho, M. S.

Publications and source records attributed to Ho, M. S..

3 recordsLinked to original sources

bioRxiv2023

The autophagy protein Atg9 functions in glia and contributes to parkinsonian symptoms in a Drosophila model of Parkinson's disease

Parkinsons disease (PD) is a progressive neurodegenerative disorder characterized by the motor deficits, selective loss of dopaminergic (DA) neurons, and the brain accumulation of -synuclein (-syn)-composed protein aggregates called Lewy bodies (LBs). Whereas dysfunction in the protein degradation pathway, like autophagy in neurons, has been demonstrated as a critical mechanism for eliminating protein aggregates in PD, how protein aggregates are eliminated in the other brain cell type, glia, is less well characterized. In the present study, we show that Atg9, the only transmembrane protein in the core autophagy pathway, is highly expressed in Drosophila adult brain glia. Results from immunostaining and live-cell imaging analysis reveal that a significant portion of Atg9 localizes to the trans-Golgi network (TGN), autophagosomes, and lysosomes in glia; Atg9 is persistently in contact with these organelles. Lacking glial atg9 reduces the number of omegasome and autophagosome and impairs autophagic substrate degradation, suggesting that glial Atg9 participates in the early steps of autophagy, hence the control of autophagic degradation. Importantly, loss of glial atg9 induces parkinsonian symptoms in Drosophila including progressive DA neuron loss and locomotion deficits. Our findings identify a functional role of Atg9 in glial autophagy and establish a potential link between glial autophagy and PD. These results provide new insights on the underlying mechanism of PD.

neuroscience↗

bioRxiv2023

A Pvr-AP-1-Mmp1 signaling pathway is activated in astrocytes upon traumatic brain injury

Traumatic brain injury (TBI) caused by external mechanical forces is a major health burden worldwide, but the underlying mechanism in glia remains largely unclear. We report herein that Drosophila adults exhibit a defective blood-brain-barrier (BBB), elevated innate immune responses, and astrocyte swelling upon consecutive strikes with a high-impact trauma device. RNA sequencing (RNA-seq) analysis of these astrocytes revealed upregulated expression of genes encoding PDGF and VEGF receptor-related (Pvr, a receptor tyrosine kinase (RTK)), adaptor protein complex 1 (AP-1, a transcription factor complex of the c-Jun N-terminal Kinase (JNK) pathway) composed of Jun-related antigen (Jra) and kayak (kay), and matrix metalloproteinase 1 (Mmp1) following TBI. Interestingly, Pvr is both required and sufficient for AP-1 and Mmp1 upregulation, while knockdown of AP-1 expression in the background of Pvr overexpression in astrocytes rescued Mmp1 upregulation upon TBI, indicating that Pvr acts as the upstream receptor for the downstream AP-1-Mmp1 transduction. Moreover, dynamin-associated endocytosis was found to be an important regulatory step in downregulating Pvr signaling. Our results identify a new Pvr-AP-1-Mmp1 signaling pathway in astrocytes in response to TBI, providing potential targets for developing new therapeutic strategies of TBI. Main PointsO_LIThe study provided RNA-seq data of astrocytes following traumatic brain injury (TBI) C_LIO_LIGenes involved in endocytic trafficking are upregulated in astrocytes after TBI C_LIO_LIA new Pvr-AP-1-Mmp1 pathway is activated in astrocytes following TBI. C_LIO_LIInhibition of endocytosis in astrocytes upregulates the Pvr-AP-1-Mmp1 signaling. C_LI

neuroscience↗

bioRxiv2021

A LRRK2/dLRRK-mediated lysosomal pathway that contributes to glial cell death and DA neuron survival

Mutations in leucine-rich repeat kinase 2 (LRRK2) are the most common cause of familial and sporadic Parkinsons disease (PD). A plethora of evidence has indicated a role for LRRK2 in endolysosomal trafficking in neurons, while LRRK2 function in glia, although highly expressed, remains largely unknown. Here we present evidence that LRRK2/dLRRK mediates a glial lysosomal pathway that contributes to the mechanism of PD. Independent of its kinase activity, glial LRRK2/dLRRK knockdown in the immortalized microglial cells or flies results in enlarged and swelling lysosomes fewer in number. These lysosomes are less mobile, wrongly acidified, and exhibit defective membrane permeability and reduced activity of the lysosome hydrolase cathespin B. In addition, microglial LRRK2 depletion causes increased Caspase 3 levels, leading to glial apoptosis, dopaminergic neurodegeneration, and locomotor deficits in an age-dependent manner. Taken together, these findings demonstrate a functional role of LRRK2/dLRRK in regulating the glial lysosomal pathway; deficits in lysosomal biogenesis and function linking to glial apoptosis potentially underlie the mechanism of DA neurodegeneration, contributing to the progression of PD.

neuroscience↗