The role of RAB10 and RAB29 in endolysosomal trafficking alterations mediated by pathogenic LRRK2
Year: 2024
Type: dissertation
Abstract: Point mutations in the gene encoding the Leucine-Rich Repeat Kinase 2 (LRRK2) are \nthe most common cause of autosomal dominant familial Parkinson’s Disease, while certain \nvariants can also increase risk of developing sporadic PD. LRRK2 has been implicated in \nseveral cellular processes including mitochondrial function, cytoskeletal dynamics and \nvesicular trafficking events. The latter include endocytosis, autophagy, retromer-mediated \nrecycling and endolysosomal trafficking pathways. The exact molecular mechanisms \nresponsible for the LRRK2-mediated defects in these trafficking pathways remain largely \nunknown. \nA subset of the RAB family of small GTPases including RAB8A and RAB10 have been \nidentified to act as LRRK2 substrates, and RAB29 is an important LRRK2 interacting protein. \nPrevious work showed that pathogenic LRRK2 mediates defects in the endolysosomal \ndegradation and recycling of the Epidermal Growth Factor Receptor (EGFR) by \nphosphorylating and inactivating RAB8A, which causes a decrease in RAB7A activity. Here, \nwe analyzed the role of the most prominent LRRK2 kinase substrate RAB10 and the role of \nthe LRRK2 interactor RAB29 in the trafficking defects mediated by pathogenic G2019S \nLRRK2. We find that expression of active RAB10 rescues the G2019S LRRK2-mediated \nphenotypes on endolysosomal trafficking, while RAB10 knockdown mimics those defects \nwhich correlates with a decrease in RAB7A activity, identical to that previously described \nfor RAB8A. \nThe EGFR endolysosomal trafficking impairments caused by either G2019S LRRK2 \nexpression or RAB10 knockdown results in the accumulation of EGF in a RAB4-positive \nendocytic recycling compartment, which is reversed by active RAB7A, active RAB8A or \nactive RAB10 expression but not by either of their WT or inactive versions. \nFurthermore, we find that WT RAB29, previously reported to recruit LRRK2 to the \nGolgi Apparatus (GA), efficiently rescues G2019S LRRK2-caused impairments in EGFR \ndegradation and reverts the accumulation of EGF in a RAB4-positive endocytic recycling \ncompartment, without causing LRRK2 recruitment to the Golgi apparatus. Inactive variants \nof RAB29 are unable to rescue the described impairments. Upon higher expression levels, \nWT RAB29 is able to recruit LRRK2 to the Golgi apparatus but fails to rescue the G2019S \nLRRK2-mediated deficits in EGFR trafficking. \nFinally, WT RAB29 but not its inactive variants reverts the described EGFR \ntrafficking impairments mediated by not only G2019S LRRK2 expression, but also by knockdown of either RAB8A or RAB10 or dominant-negative RAB7A expression, in a \nmanner which is independent of Golgi apparatus structural integrity. \nTogether, these data suggest a mechanism underlying the endolysosomal trafficking \ndeficits mediated by pathogenic LRRK2 by which it phosphorylates RAB8A and RAB10 thus \ncausing their inactivation, which also leads to a decrease in RAB7A activity. We find that \nRAB8A and RAB10 play redundant roles in regulating EGFR recycling and endolysosomal \ntrafficking events. Lastly, we report a novel role for RAB29 in regulating endocytic recycling \nand endolysosomal trafficking events which is independent on its role at the Golgi complex.
Author: Romo Lozano, María
Language: English
Subfield: Cell Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W7024563873