Rapamycin and Chloroquine: The In Vitro and In Vivo Effects of Autophagy-Modifying Drugs Show Promising Results in Valosin Containing Protein Multisystem Proteinopathy

Abstract

Mutations in the valosin containing protein (VCP) gene cause hereditary Inclusion body myopathy (hIBM) associated with Paget disease of bone (PDB), frontotemporal dementia (FTD), more recently termed multisystem proteinopathy (MSP). Affected individuals exhibit scapular winging and die from progressive muscle weakness, and cardiac and respiratory failure, typically in their 40s to 50s. Histologically, patients show the presence of rimmed vacuoles and TAR DNA-binding protein 43 (TDP-43)-positive large ubiquitinated inclusion bodies in the muscles. We have generated a VCPR155H/+ mouse model which recapitulates the disease phenotype and impaired autophagy typically observed in patients with VCP disease. Autophagy-modifying agents, such as rapamycin and chloroquine, at pharmacological doses have previously shown to alter the autophagic flux. Herein, we report results of administration of rapamycin, a specific inhibitor of the mechanistic target of rapamycin (mTOR) signaling pathway, and chloroquine, a lysosomal inhibitor which reverses autophagy by accumulating in lysosomes, responsible for blocking autophagy in 20-month old VCPR155H/+ mice. Rapamycin-treated mice demonstrated significant improvement in muscle performance, quadriceps histological analysis, and rescue of ubiquitin, and TDP-43 pathology and defective autophagy as indicated by decreased protein expression levels of LC3-I/II, p62/SQSTM1, optineurin and inhibiting the mTORC1 substrates. Conversely, chloroquine-treated VCPR155H/+ mice revealed progressive muscle weakness, cytoplasmic accumulation of TDP-43, ubiquitin-positive inclusion bodies and increased LC3-I/II, p62/SQSTM1, and optineurin expression levels. Our in vitro patient myoblasts studies treated with rapamycin demonstrated an overall improvement in the autophagy markers. Targeting the mTOR pathway ameliorates an increasing list of disorders, and these findings suggest that VCP disease and related neurodegenerative multisystem proteinopathies can now be included as disorders that can potentially be ameliorated by rapalogs.

Countervailing, time-dependent effects on host autophagy promote intracellular survival of Leishmania

“…These findings were strengthened by monitoring levels of p62 under the conditions above, as shown in Supplementary Fig 3 (lanes 3 & 4). Notably, leishmania did not affect accumulation of LC3-II in response to chloroquine (Fig 2A & B), that acts through a distinct pathway from that of rapamycin (30,31). These findings further indicate that the inhibitory effect of leishmania infection on autophagy is selective.…”

Chloroquine improves left ventricle diastolic function in streptozotocin-induced diabetic mice

“…CQ accumulates LC3-II, a key step in autophagosome formation, by preventing the degradation of LC3-II-containing autolysosomes 23. The adaptor protein p62 (sequestosome-1) can bind directly to LC3 to facilitate degradation of ubiquitinated protein aggregated by autophagy 24. The accumulation of p62 was associated with decreased autophagy by CQ (Figure 4).…”

Activation of the NLRP3 Inflammasome Is Associated with Valosin-Containing Protein Myopathy

“…Muscle pathology leads to an increase in autophagy markers such as sequestosome 1 (p62/ SQSTM1 ) [27, 42, 43]. The p62/ SQSTM1 interacts with the autophagic effector protein Light Chain 3 (LC3-I/II) to mediate the uptake of aggregated proteins [44, 45]. Inclusions seen in the muscles and brain of VCP patients contain ubiquitin, beta amyloid, p62/ SQSTM1 and TDP-43 (‘classic’ hallmark markers of VCP disease) are also observed in other neurodegenerative disorders, such as Alzheimer disease (AD) and more recently Amyotrophic Lateral Sclerosis (ALS), thus implicating common inflammatory pathways in their pathogenesis [46–50].…”