Cytosolic PINK1 promotes the targeting of ubiquitinated proteins to the aggresome-autophagy pathway during proteasomal stress

During proteasomal stress, cells can alleviate the accumulation of polyubiquitinated proteins by targeting them to perinuclear aggresomes for autophagic degradation, but the mechanism underlying the activation of this compensatory pathway remains unclear. Here we report that PINK1-s, a short form of Parkinson disease (PD)-related protein kinase PINK1 (PTEN induced putative kinase 1), is a major regulator of aggresome formation. PINK1-s is extremely unstable due to its recognition by the N-end rule pathway, and tends to accumulate in the cytosol during proteasomal stress. Overexpression of PINK1-s induces aggresome formation in cells with normal proteasomal activities, while loss of PINK1-s function leads to a significant decrease in the efficiency of aggresome formation induced by proteasomal inhibition. PINK1-s exerts its effect through phosphorylation of the ubiquitin-binding protein SQSTM1 (sequestosome 1) and increasing its ability to sequester polyubiquitinated proteins into aggresomes. These findings pinpoint PINK1-s as a sensor of proteasomal activities that transduces the proteasomal impairment signal to the aggresome formation machinery.     

Bullous pemphigoid‐like skin blistering disease in a rhesus macaque (Macaca mulatta)

Autoimmune bullous disease is very uncommon in non‐human primates. We observed a bullous skin disease in a male rhesus monkey while conducting porcine islet xenotransplantation. Fifty days after the transplantation, multiple bullous skin lesions were observed. There was no mucosal involvement. Skin biopsy results demonstrated a subepidermal blister with no necrotic keratinocytes. Immunofluorescent staining showed linear IgG deposition at the roof of the blister. These skin lesions spontaneously disappeared. Considering these results, this monkey was diagnosed with bullous pemphigoid (BP). As far as we know, this is the first report of BP in non‐human primates.     

α-Galactosidase delivery using 30Kc19-human serum albumin nanoparticles for effective treatment of Fabry disease

Fabry disease is a genetic lysosomal storage disease caused by deficiency of α-galactosidase, the enzyme-degrading neutral glycosphingolipid that is transported to lysosome. Glycosphingolipid accumulation by this disease causes multi-organ dysfunction and premature death of the patient. Currently, enzyme replacement therapy (ERT) using recombinant α-galactosidase is the only treatment available for Fabry disease. To maximize the efficacy of treatment, enhancement of cellular delivery and enzyme stability is a challenge in ERT using α-galactosidase. In this study, protein nanoparticles using human serum albumin (HSA) and 30Kc19 protein, originating from silkworm, were used to enhance the delivery and intracellular α-galactosidase stability. 30Kc19-HSA nanoparticles loaded with the α-galactosidase were formed by desolvation method. 30Kc19-HSA nanoparticles had a uniform spherical shape and were well dispersed in cell culture media. 30Kc19-HSA nanoparticles had negligible toxicity to human cells. The nanoparticles exhibited enhanced cellular uptake and intracellular stability of delivered α-galactosidase in human foreskin fibroblast. Additionally, they showed enhanced globotriaosylceramide degradation in Fabry patients’ fibroblasts. It is expected that 30Kc19-HSA protein nanoparticles could be used as an effective tool for efficient delivery and enhanced stability of drugs.     

The non-coding RNA composition of the mitotic chromosome by 5′-tag sequencing

Mitotic chromosomes are one of the most commonly recognized sub-cellular structures in eukaryotic cells. Yet basic information necessary to understand their structure and assembly, such as their composition, is still lacking. Recent proteomic studies have begun to fill this void, identifying hundreds of RNA-binding proteins bound to mitotic chromosomes. However, by contrast, there are only two RNA species (U3 snRNA and rRNA) that are known to be associated with the mitotic chromosome, suggesting that there are many mitotic chromosome-associated RNAs (mCARs) not yet identified. Here, using a targeted protocol based on 5′-tag sequencing to profile the mammalian mCAR population, we report the identification of 1279 mCARs, the majority of which are ncRNAs, including lncRNAs that exhibit greater conservation across 60 vertebrate species than the entire population of lncRNAs. There is also a significant enrichment of snoRNAs and specific SINE RNAs. Finally, ∼40% of the mCARs are presently unannotated, many of which are as abundant as the annotated mCARs, suggesting that there are also many novel ncRNAs in the mCARs. Overall, the mCARs identified here, together with the previous proteomic and genomic data, constitute the first comprehensive catalogue of the molecular composition of the eukaryotic mitotic chromosomes.     

Aminoacyl-tRNA synthetase-interacting multifunctional protein 1 suppresses tumor growth in breast cancer-bearing mice by negatively regulating myeloid-derived suppressor cell functions

Myeloid-derived suppressor cells (MDSCs) are one of the most important cell types that contribute to negative regulation of immune responses in the tumor microenvironment. Recently, aminoacyl-tRNA synthetase-interacting multifunctional protein 1 (AIMP1), a novel pleiotropic cytokine, was identified as an antitumor protein that inhibits angiogenesis and induces antitumor responses. However, the effect of AIMP1 on MDSCs in the tumor environment remains unclear. In the present study, we demonstrated that AIMP1 significantly inhibited tumor growth in 4T1 breast cancer-bearing mice and reduced MDSCs population of tumor sites and spleens of tumor-bearing mice. AIMP1 reduced expansion of MDSCs from bone marrow-derived cells in the tumor-conditioned media. AIMP1 also negatively regulated suppressive activities of MDSCs by inhibiting IL-6 and NO production, and Arg-1 expression. Furthermore, treatment of breast cancer-bearing mice with AIMP1 decreased the capacity of MDSCs to suppress T cell proliferation and Treg cell induction. Western blot and inhibition experiments showed that downregulation of MDSCs functions by AIMP1 may result from attenuated activation of STATs, Akt, and ERK. These findings indicate that AIMP1 plays an essential role in negative regulation of suppressive functions of MDSCs. Therefore, it has a significant potential as a therapeutic agent for cancer treatment.     

Effects of IP<Subscript>3</Subscript>R2 Receptor Deletion in the Ischemic Mouse Retina

Glial cells in the diseased nervous system undergo a process known as reactive gliosis. Gliosis of retinal Müller glial cells is characterized by an upregulation of glial fibrillary acidic protein and frequently by a reduction of inward K⁺ current amplitudes. Purinergic signaling is assumed to be involved in gliotic processes. As previously shown, lack of the nucleotide receptor P2Y₁ leads to an altered regulation of K⁺ currents in Müller cells of the ischemic retina. Here, we asked first whether this effect is mediated by the IP₃ receptor subtype 2 (IP₃R2) known as the major downstream signaling target of P2Y₁ in Müller cells. The second question was whether lack of IP₃R2 affects neuronal survival in the control and ischemic retina. Ischemia was induced in wild type and IP₃R2-deficient (IP ₃ R2 ^?/?) mice by transient elevation of the intraocular pressure. Immunostaining and TUNEL labelling were used to quantify neuronal cell loss. The downregulation of inward K⁺ currents in Müller cells from ischemic IP ₃ R2 ^?/? retinae was less strong than in wild type animals. The reduction of the number of cells in the ganglion cell layer and of calretinin- and calbindin-positive cells 7 days after ischemia was similar in wild type and IP ₃ R2 ^?/? mice. However, IP₃R2 deficiency led to an increased number of TUNEL-positive cells in the outer nuclear layer at 1 day and to an enhanced postischemic loss of photoreceptors 7 days after ischemia. This implies that IP₃R2 is involved in some but not all aspects of signaling in Müller cells after an ischemic insult.     

Seasonal changes in blood cells and biochemical parameters in the Mongolian hamster (<Emphasis Type="Italic">Allocricetulus curtatus</Emphasis>)

It was shown previously that the Mongolian hamster (Allocricetulus curtatus) is a mammalian species with irregular short hibernation. The purpose of the present study was to determine how this status affects seasonal changes in the biochemical and hematological parameters in A. curtatus males under a natural temperature and light regime. It was found that a reduction in circulating white blood cells, specifically lymphocytes, neutrophils, eosinophils, basophils, and monocytes, occurred in winter and bilirubin levels increased in spring. These characteristics make Mongolian hamsters closer to the true hibernating species. At the same time, the character of seasonal changes in the number of red blood cells, glucose, total protein, creatinine, and albumin is closer to species with torpor.