Changes in Liver Lipidomic Profile in G2019S-LRRK2 Mouse Model of Parkinson's Disease

The identification of Parkinson's disease (PD) biomarkers has become a main goal for the diagnosis of this neurodegenerative disorder. PD has not only been intrinsically related to neurological problems, but also to a series of alterations in peripheral metabolism. The purpose of this study was to identify metabolic changes in the liver in mouse models of PD with the scope of finding new peripheral biomarkers for PD diagnosis. To achieve this goal, we used mass spectrometry technology to determine the complete metabolomic profile of liver and striatal tissue samples from WT mice, 6-hydroxydopamine-treated mice (idiopathic model) and mice affected by the G2019S-LRRK2 mutation in LRRK2/PARK8 gene (genetic model). This analysis revealed that the metabolism of carbohydrates, nucleotides and nucleosides was similarly altered in the liver from the two PD mouse models. However, long-chain fatty acids, phosphatidylcholine and other related lipid metabolites were only altered in hepatocytes from G2019S-LRRK2 mice. In summary, these results reveal specific differences, mainly in lipid metabolism, between idiopathic and genetic PD models in peripheral tissues and open up new possibilities to better understand the etiology of this neurological disorder.

Protocols to induce and study ciliogenesis

Primary cilia (PC) are sensory organelles that function as cellular antennas, transmitting signals between the extracellular and intracellular spaces in many vertebrate tissues. The cell generates and assembles PC through a highly regulated process called ciliogenesis. This complex process is involved in several physiological functions, including embryonic development, locomotion, cell cycle regulation or energetic homeostasis control. In general, when a cell finishes its cell division, the oldest centriole usually migrates to the plasma membrane and becomes a basal body that gives rise to the formation of a cilium. For this reason, the presence of cilia is incompatible with cell division, so when a cell is going to divide, the cilium and the basal body disappear. Ciliogenesis is triggered by various stimuli, all of them related to cell cycle blockade. This cell cycle, and ciliogenesis induction, can be observed by: (1) the influence of growth factors (lack of serum and consequent inability to promote cell cycle exit and increase the proportion of cells in G₀); (2) pharmacological cell cycle inhibitors (staurosporine or etoposide); or (3) physiological cell cycle inhibition (excessive contact between neighboring cells). Evaluation of ciliogenesis induction is vitally important for the study of diseases related to ciliary dysfunction, called ciliopathies. That is why the use of correct protocols for inducing cilia formation and an accurate posterior visualization of the cilia after performing said protocols are essential parts in the study of these diseases. To facilitate this task, here we described detailed protocols to induce ciliogenesis in vitro and visualize PC by immunofluorescence microscopy in cultured cells.