Human LAMP2 (Lysosome-associated membrane glycoprotein 2) ELISA Kit

AimAutophagy is a subcellular degradation mechanism important for muscle maintenance. Hypertension induces well-characterized pathological changes to the heart and is associated with impaired function and increased apoptotic signalling in skeletal muscle. We examined whether essential hypertension affects several autophagy markers in skeletal and cardiac muscle. MethodsImmunoblotting and qRT-PCR were used to measure autophagy-related proteins/mRNA in multiple skeletal muscles as well as left ventricle (LV) of spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY). ResultsSkeletal muscles of hypertensive rats had decreased (P<0.01) cross-sectional area of type I fibres (e.g. soleus WKY: 2952.964.4m(2) vs. SHR: 2579.9 +/- 85.8m(2)) and a fibre redistribution towards a fast' phenotype. Immunoblot analysis revealed that some SHR skeletal muscles displayed a decreased LC3II/I ratio (P<0.05), but none showed differences in p62 protein. LC3 and LAMP2 mRNA levels were increased approx. 2-3-fold in all skeletal muscles (P<0.05), while cathepsin activity, cathepsin L mRNA and Atg7 protein were increased 16-17% (P<0.01), 2-3-fold (P<0.05) and 29-49% (P<0.01), respectively, in fast muscles of hypertensive animals. Finally, protein levels of BAG3, a marker of chaperone-assisted selective autophagy, were 18-25% lower (P<0.05) in SHR skeletal muscles. In the LV of SHR, LC3I and p62 protein were elevated 34% (P<0.05) and 47% (P<0.01), respectively. Furthermore, p62 mRNA was 68% higher (P<0.05), while LAMP2 mRNA was 45% lower (P<0.05), in SHR cardiac muscle. There was no difference in Beclin1, Atg7, Bnip3 or BAG3 protein in the LV between strains. ConclusionThese results suggest that autophagy is altered in skeletal and cardiac muscle during hypertension.

Loss of function of the FIG4 gene causes Charcot-Marie-Tooth disease (CMT)-4J with many features also found in motor neuron disease (MND). Mechanisms for the degeneration are unknown. We investigated this using Fig4-deficient pale tremor (plt) mice, a mouse model of CMT4J. Ultrastructural studies in sensory neurons of dorsal root ganglion (DRG) confirmed abundant vacuoles with membrane disruption. The vacuoles became detectable as early as postnatal day 4 in the DRG. However, the vacuoles were absent or minimal in the spinal motor neurons or cortical neurons in 2- to 5-week-old plt mice. Instead, a large number of electron-dense organelles, reminiscent of those in lysosomal storage disorders, accumulated in the motor neurons, but not in the sensory neurons of DRG. This accumulation was associated with increased levels of lysosomal proteins, such as LAMP2 and NPC1, but not mannose-6-phosphate receptor, an endosomal protein that is usually excluded from the lysosomes. Our results suggest that Fig4 deficiency affects motor neurons differently from sensory neurons by mechanisms involving excessive retention of molecules in lysosomes or disruption of vacuolated organelles. These two distinct pathological changes may contribute to neuronal degeneration.