Porphyromonas gingivalis, a periodontal pathogen, impairs post-infarcted myocardium by inhibiting autophagosome-lysosome fusion / 国际口腔科学杂志·英文版

While several previous studies have indicated the link between periodontal disease (PD) and myocardial infarction (MI), the underlying mechanisms remain unclear. Autophagy, a cellular quality control process that is activated in several diseases, including heart failure, can be suppressed by Porphyromonas gingivalis (P.g.). However, it is uncertain whether autophagy impairment by periodontal pathogens stimulates the development of cardiac dysfunction after MI. Thus, this study aimed to investigate the relationship between PD and the development of MI while focusing on the role of autophagy. Neonatal rat cardiomyocytes (NRCMs) and MI model mice were inoculated with wild-type P.g. or gingipain-deficient P.g. to assess the effect of autophagy inhibition by P.g. Wild-type P.g.-inoculated NRCMs had lower cell viability than those inoculated with gingipain-deficient P.g. This study also revealed that gingipains can cleave vesicle-associated membrane protein 8 (VAMP8), a protein involved in lysosomal sensitive factor attachment protein receptors (SNAREs), at the 47th lysine residue, thereby inhibiting autophagy. Wild-type P.g.-inoculated MI model mice were more susceptible to cardiac rupture, with lower survival rates and autophagy activity than gingipain-deficient P.g.-inoculated MI model mice. After inoculating genetically modified MI model mice (VAMP8-K47A) with wild-type P.g., they exhibited significantly increased autophagy activation compared with the MI model mice inoculated with wild-type P.g., which suppressed cardiac rupture and enhanced overall survival rates. These findings suggest that gingipains, which are virulence factors of P.g., impair the infarcted myocardium by cleaving VAMP8 and disrupting autophagy. This study confirms the strong association between PD and MI and provides new insights into the potential role of autophagy in this relationship.

ORP8 acts as a lipophagy receptor to mediate lipid droplet turnover

Lipophagy, the selective engulfment of lipid droplets (LDs) by autophagosomes for lysosomal degradation, is critical to lipid and energy homeostasis. Here we show that the lipid transfer protein ORP8 is located on LDs and mediates the encapsulation of LDs by autophagosomal membranes. This function of ORP8 is independent of its lipid transporter activity and is achieved through direct interaction with phagophore-anchored LC3/GABARAPs. Upon lipophagy induction, ORP8 has increased localization on LDs and is phosphorylated by AMPK, thereby enhancing its affinity for LC3/GABARAPs. Deletion of ORP8 or interruption of ORP8-LC3/GABARAP interaction results in accumulation of LDs and increased intracellular triglyceride. Overexpression of ORP8 alleviates LD and triglyceride deposition in the liver of ob/ob mice, and Osbpl8-/- mice exhibit liver lipid clearance defects. Our results suggest that ORP8 is a lipophagy receptor that plays a key role in cellular lipid metabolism.

Evidence of autophagic vesicles in a patient with Lisch corneal dystrophy / Evidência de vesículas autofágicas em paciente com distrofia corneana de Lisch

ABSTRACT Lisch corneal dystrophy is a rare corneal disease characterized by the distinctive feature of highly vacuolated cells. Although this feature is important, the nature of these vacuoles within corneal cells remains unknown. Here, we sought to analyze corneal cells from a patient diagnosed with Lisch dystrophy to characterize the vacuoles within these cells. Analyses using histopathology examination, confocal microscopy, and transmission electron microscopy were all consistent with previous descriptions of Lisch cells. Importantly, the vacuoles within these cells appeared to be autophagosomes and autolysosomes, and could be stained with an anti-microtubule-associated protein 1A/1B-light chain 3 (LC3) antibody. Taken together, these findings indicate that the vacuoles we observed within superficial corneal cells of a patient with Lisch corneal dystrophy constituted autophagosomes and autolysosomes; this finding has not been previously reported and suggests a need for further analyses to define the role of autophagy in this ocular disease.

RESUMO A distrofia corneana de Lisch é uma doença rara, caracterizada principalmente pela presença de células altamente vacuoladas. Embora esta característica seja importante, a natureza desses vacúolos dentro das células da córnea permanece des conhecida. Aqui, procuramos analisar as células da córnea de um paciente diagnosticado com distrofia de Lisch para caracte rizar os vacúolos dentro dessas células. Análises utilizando exame histopatológico, microscopia confocal e microscopia eletrônica de transmissão foram todas consistentes com descrições previas de células de Lisch. Importante, os vacúolos dentro dessas células pareciam ser autofagossomos e autolisossomos, e po deriam ser corados com um anticorpo proteico 1A/1B-cadeia leve 3 (LC3) da proteína anti-microtúbulo associado a microtúbulos. Em conjunto, esses achados indicam que os vacúolos observados nas células superficiais da córnea de um paciente com distrofia corneana de Lisch constituíram autofagossomos e autolisossomos. Esse achado não foi relatado anteriormente e sugere a necessidade de mais análises para definir o papel da autofagia nessa doença ocular.

ULK1 and JNK are involved in mitophagy incurred by LRRK2 G2019S expression

Mutations in LR RK2 (Leucine rich repeat kinase 2) are a major cause of Parkinson's disease (PD). We and others reported recently that expression of the pathogenic gainof-function mutant form of LRRK2, LRRK2 G2019S, induces mitochondrial fission in neurons through DLP1. Here we provide evidence that expression of LRRK2 G2019S stimulates mitochondria loss or mitophagy. We have characterized several LRRK2 interacting proteins and found that LRRK2 interacts with ULK1 which plays an essential role in autophagy. Knockdown of either ULK1 or DLP1 expression with shRNAs suppresses LRRK2 G2019S expression-induced mitochondrial clearance, suggesting that LRRK2 G2019S expression induces mitochondrial fission through DLP1 followed by mitophagy via an ULK1 dependent pathway. In addition to ULK1, we found that LRRK2 interacts with the endogenous MKK4/7, JIP3 and coordinates with them in the activation of JNK signaling. Interestingly, LRRK2 G2019S-induced loss of mitochondria can also be suppressed by 3 different JNK inhibitors, implying the involvement of the JNK pathway in the pathogenic mechanism of mutated LRRK2. Thus our findings may provide an insight into the complicated pathogenesis of PD as well as some clues to the development of novel therapeutic strategies.