Molecular Markers for Granulovacuolar Degeneration Are Present in Rimmed Vacuoles

Abstract

BackgroundRimmed vacuoles (RVs) are round-oval cytoplasmic inclusions, detected in muscle cells of patients with myopathies, such as inclusion body myositis (IBM) and distal myopathy with RVs (DMRV). Granulovacuolar degeneration (GVD) bodies are spherical vacuoles containing argentophilic and hematoxyphilic granules, and are one of the pathological hallmarks commonly found in hippocampal pyramidal neurons of patients with aging-related neurodegenerative diseases, such as Alzheimer's disease and Parkinson's disease. These diseases are common in the elderly and share some pathological features. Therefore, we hypothesized that mechanisms of vacuolar formation in RVs and GVD bodies are common despite their role in two differing pathologies. We explored the components of RVs by immunohistochemistry, using antibodies for GVD markers.MethodsSubjects included one AD case, eight cases of sporadic IBM, and three cases of DMRV. We compared immunoreactivity and staining patterns for GVD markers. These markers included: (1) tau-modifying proteins (caspase 3, cyclin-dependent kinase 5 [CDK5], casein kinase 1δ [CK1δ], and c-jun N-terminal kinase [JNK]), (2) lipid raft-associated materials (annexin 2, leucine-rich repeat kinase 2 [LRRK2], and flotillin-1), and (3) other markers (charged multi-vesicular body protein 2B [CHMP2B] and phosphorylated transactive response DNA binding protein-43 [pTDP43]) in both GVD bodies and RVs. Furthermore, we performed double staining of each GVD marker with pTDP43 to verify the co-localization.ResultsGVD markers, including lipid raft-associated proteins and tau kinases, were detected in RVs. CHMP2B, pTDP43, caspase 3, LRRK2, annexin 2 and flotillin-1 were detected on the rim and were diffusely distributed in the cytoplasm of RV-positive fibers. CDK5, CK1δ and JNK were detected only on the rim. In double staining experiments, all GVD markers colocalized with pTDP43 in RVs.ConclusionsThese results suggest that RVs of muscle cells and GVD bodies of neurons share a number of molecules, such as raft-related proteins and tau-modifying proteins.

Midget retinal ganglion cell dendritic and mitochondrial degeneration is an early feature of human glaucoma

“…3A and C). The appearance of vacuoles is an age- and disease-related change observed in neurons in aged rodents (de Estable-Puig and Estable-Puig, 1975) and post-mortem human tissue from various dementias (Ball and Lo, 1977; Nakamori et al , 2013). Granulovacuolar degeneration bodies, a hallmark of Alzheimer’s disease, are late-stage autophagocytic vacuoles, the accumulation of which may relate to incomplete autophagy (Funk et al , 2011).…”

Untangling the origin and function of granulovacuolar degeneration bodies in neurodegenerative proteinopathies

“…However, in the GVB model in cultured neurons EEA1 was absent from GVBs – whereas early endosomes were clearly detected in a punctate staining pattern –, indicating a more prominent involvement of late than early stage endosomal proteins in GVBs. In line with this, also the membrane-associated protein Flotillin-1 that localizes to the plasma membrane as well as the membrane of late endosomes and lysosomes, co-localizes with GVBs in the human and mouse brain [ 95 , 148 ]. Flotillin-1 is additionally being used as an exosomal membrane marker, raising the possibility that some GVBs undergo exocytosis, although GVBs are typically not observed in association with the plasma membrane and to date experimental data supporting GVB release is lacking.…”

“…This suggest that selective targeting or degradation mechanisms are at play in GVBs. Furthermore, a plethora of other proteins involved in various cellular processes have been found in GVBs (for a tabular overview of GVB-localizing proteins discovered till 2016 see [ 65 ]; in our literature search, we additionally came across publications reporting GVB localization in tissue for PKR [ 135 ], phosphorylated p300 [ 5 ], PICALM [ 2 ], annexin2 [ 95 ], LRRK2 [ 95 ] and reticulon-3 [ 36 ] and publications after 2016 showed the GVB localization of TMEM230 [ 119 ], Dvl3 [ 93 ], rapsyn [ 93 ], APC [ 93 ], PrP [ 142 ], Golgin A4 [ 69 ], phosphorylated (S65) ubiquitin [ 45 ], SSBP1 [ 45 ], nucleolin [ 38 ], SIL1 [ 73 ], NF-κB [ 145 ], GM130 [ 148 ], β-COP [ 148 ], matrin-3 [ 148 ], G3BP [ 148 ] and immunoreactivity of GVBs for an anti-sialic acid antibody [ 94 ] (for phospho-specific antibodies see Table 3 )). In conclusion, regardless of the presence of proteolytic activity markers, the GVB core harbors a variety of proteins, including various markers of cellular stress and potentially harmful proteins.…”

Expression of Concern: Molecular Markers for Granulovacuolar Degeneration Are Present in Rimmed Vacuoles

“…The Funding Statement for this article [ 1 ] states that the study received funding from the Smoking Research Foundation, which according to [ 2 ] has received financial support from the tobacco industry. In light of this issue the PLOS ONE article [ 1 ] does not comply with the journal’s policy on Funding from Tobacco Companies [ 3 ] which was implemented in 2010. Therefore, the PLOS ONE Editors issue this Expression of Concern.…”

“…We regret that this concern was not identified and addressed prior to the article’s [ 1 ] publication.…”