Ed that the mitochondrial membrane proteins, translocase inner membrane 23 (TIM23), and translocase outer mitochondrial membrane 20 (TOMM20), were increased in the cerebellum in ET cases vs. controls (TIM23: 1.3660.11 in ET cases vs. 1.0060.08 in controls, p = 0.02; TOMM20: 1.6360.87 1379592 in ET cases vs. 1.0060.14 in controls, p = 0.03) (Figure 3A?C).This increase in mitochondrial mass suggests that the decrease in AVs observed in ET cerebellum may be due to impaired AV formation. In contrast, we found that similar mitochondrial protein levels were present in the occipital cortex of both ET cases and controls (TIM23: 1.0060.16 in ET cases vs. 1.0060.Autophagy in Essential TremorFigure 1. Decreased LC3-II levels in the cerebellum of essential tremor (ET) cases and controls. LC3-II and b-actin levels in cerebellar homogenates were determined by Western blot in 10 ET cases and 11 controls. Two LC3 antibodies were used, LC3 antibody, Novus Biologicals 1384 (top panel), and LC3-II specific antibody Novus Biologicals 19167 (third panel) and the representative bands were shown (A). LC3-II levels (mean 6 SD) were significantly lower in ET cases vs. controls (B). In a linear regression model, ET disease duration inversely correlated with LC3-II level (C).When dividing our sample into three categories, ET cases with the longest disease duration had the most diminished LC3-II levels, followed by ET cases with shorter duration disease and then controls (D). ET cases displayed lower levels of calbindin than age-matched controls, consistent with PC cell loss (A, E). We also determined the LC3-II and b-actin levels in the occipital cortex in 7 ET cases and 9 controls and the representative blots were shown (F). ET cases and controls exhibited similar LC3-II levels in the occipital cortex (mean 6 SD) (G). doi:10.1371/journal.pone.0053040.gin controls; TOMM20: 1.1160.25 in ET cases vs. 1.0060.20 in controls) (Figure 3D ). We next investigated the two best characterized regulators of macroautophagy initiation: mammalian target of rapamycin (mTOR) and beclin-1. mTOR phosphorylates ULK1/2 and Atg13 complexes to inhibit autophagy, whereas GDC-0032 beclin-1 is required for Vps34 and other protein complexes to induce autophagy [25]. Thus, mTOR serves to inhibit, and beclin-1, 24195657 to promote macroautophagy. As we could not detect mTOR and phosphorylated mTOR on Western blot, like others [26,27], possibly due to the large molecular weight of mTOR and the specificity of the antibodies against post-mortem human samples. We utilized the mTOR downstream effectors, phosphorylated S6K (pS6K) and S6K as reliable readouts for mTOR activity S6K is a ribosomal serine/threonine kinase and, upon phosphorylation by mTOR, S6K facilitates ribosomal biogenesis. ET cases had a similar pS6K/S6K ratio as controls (0.8860.27 vs. 1.0060.44, p = 0.47), GDC-0980 site suggesting that the differences in mTOR activity do not directly account for the decreased LC3-II in ET (Figure 3G, H). In contrast, we found that beclin-1 level was decreased in ET cases vs. controls (0.4260.13 vs. 1.0060.35, p,0.0001)(Figure 3G, I). In a linear regression model, beclin-1 level was correlated with LC3-II level (r2 = 0.46, p,0.001), suggesting that beclin-1 could be an important rate-limiting molecule for AV formation in PCs and that beclin-1 deficiency could play a role in autophagic dysfunction in ET.DiscussionWe observed lower LC3-II protein levels in the ET cerebellum and fewer AVs in the PCs in ET. These observations suggest that.Ed that the mitochondrial membrane proteins, translocase inner membrane 23 (TIM23), and translocase outer mitochondrial membrane 20 (TOMM20), were increased in the cerebellum in ET cases vs. controls (TIM23: 1.3660.11 in ET cases vs. 1.0060.08 in controls, p = 0.02; TOMM20: 1.6360.87 1379592 in ET cases vs. 1.0060.14 in controls, p = 0.03) (Figure 3A?C).This increase in mitochondrial mass suggests that the decrease in AVs observed in ET cerebellum may be due to impaired AV formation. In contrast, we found that similar mitochondrial protein levels were present in the occipital cortex of both ET cases and controls (TIM23: 1.0060.16 in ET cases vs. 1.0060.Autophagy in Essential TremorFigure 1. Decreased LC3-II levels in the cerebellum of essential tremor (ET) cases and controls. LC3-II and b-actin levels in cerebellar homogenates were determined by Western blot in 10 ET cases and 11 controls. Two LC3 antibodies were used, LC3 antibody, Novus Biologicals 1384 (top panel), and LC3-II specific antibody Novus Biologicals 19167 (third panel) and the representative bands were shown (A). LC3-II levels (mean 6 SD) were significantly lower in ET cases vs. controls (B). In a linear regression model, ET disease duration inversely correlated with LC3-II level (C).When dividing our sample into three categories, ET cases with the longest disease duration had the most diminished LC3-II levels, followed by ET cases with shorter duration disease and then controls (D). ET cases displayed lower levels of calbindin than age-matched controls, consistent with PC cell loss (A, E). We also determined the LC3-II and b-actin levels in the occipital cortex in 7 ET cases and 9 controls and the representative blots were shown (F). ET cases and controls exhibited similar LC3-II levels in the occipital cortex (mean 6 SD) (G). doi:10.1371/journal.pone.0053040.gin controls; TOMM20: 1.1160.25 in ET cases vs. 1.0060.20 in controls) (Figure 3D ). We next investigated the two best characterized regulators of macroautophagy initiation: mammalian target of rapamycin (mTOR) and beclin-1. mTOR phosphorylates ULK1/2 and Atg13 complexes to inhibit autophagy, whereas beclin-1 is required for Vps34 and other protein complexes to induce autophagy [25]. Thus, mTOR serves to inhibit, and beclin-1, 24195657 to promote macroautophagy. As we could not detect mTOR and phosphorylated mTOR on Western blot, like others [26,27], possibly due to the large molecular weight of mTOR and the specificity of the antibodies against post-mortem human samples. We utilized the mTOR downstream effectors, phosphorylated S6K (pS6K) and S6K as reliable readouts for mTOR activity S6K is a ribosomal serine/threonine kinase and, upon phosphorylation by mTOR, S6K facilitates ribosomal biogenesis. ET cases had a similar pS6K/S6K ratio as controls (0.8860.27 vs. 1.0060.44, p = 0.47), suggesting that the differences in mTOR activity do not directly account for the decreased LC3-II in ET (Figure 3G, H). In contrast, we found that beclin-1 level was decreased in ET cases vs. controls (0.4260.13 vs. 1.0060.35, p,0.0001)(Figure 3G, I). In a linear regression model, beclin-1 level was correlated with LC3-II level (r2 = 0.46, p,0.001), suggesting that beclin-1 could be an important rate-limiting molecule for AV formation in PCs and that beclin-1 deficiency could play a role in autophagic dysfunction in ET.DiscussionWe observed lower LC3-II protein levels in the ET cerebellum and fewer AVs in the PCs in ET. These observations suggest that.
