Loss of Chondroitin Sulfate Modification Causes Inflammation and Neurodegeneration in skt Mice

Abstract

One major aspect of the aging process is the onset of chronic, low-grade inflammation that is highly associated with agerelated diseases. The molecular mechanisms that regulate these processes have not been fully elucidated. We have identified a spontaneous mutant mouse line, small with kinky tail (skt), that exhibits accelerated aging and age-related disease phenotypes including increased inflammation in the brain and retina, enhanced age-dependent retinal abnormalities including photoreceptor cell degeneration, neurodegeneration in the hippocampus, and reduced lifespan. By positional cloning, we identified a deletion in chondroitin sulfate synthase 1 (Chsy1) that is responsible for these phenotypes in skt mice. CHSY1 is a member of the chondroitin N-acetylgalactosaminyltransferase family that plays critical roles in the biosynthesis of chondroitin sulfate, a glycosaminoglycan (GAG) that is attached to the core protein to form the chondroitin sulfate proteoglycan (CSPG). Consistent with this function, the Chsy1 mutation dramatically decreases chondroitin sulfate GAGs in the retina and hippocampus. In addition, macrophage and neutrophil populations appear significantly altered in the bone marrow and spleen of skt mice, suggesting an important role for CHSY1 in the functioning of these immune cell types. Thus, our study reveals a previously unidentified impact of CHSY1 in the retina and hippocampus. Specifically, chondroitin sulfate (CS) modification of proteins by CHSY1 appears critical for proper regulation of immune cells of the myeloid lineage and for maintaining the integrity of neuronal tissues, since a defect in this gene results in increased inflammation and abnormal phenotypes associated with age-related diseases.

Conditionally immortalised leukaemia initiating cells co-expressing Hoxa9/Meis1 demonstrate microenvironmental adaptation properties ex vivo while maintaining myelomonocytic memory

“…To study H9M-ciMPs under myelomonocytic DOX+/DOX- conditions, we focused on 8 H9M-ciMP cell lines originating from pre-selected MRV and MRV* derived cell lines. These cell lines had RVIs in the vicinity of the Ninj2 gene promoting neurite outgrowth 12 , Vps45 ( vacuolar protein sorting 45)/ Otud7b (OTU domain containing 7B) 25 , 26 , Plet1 (placenta expressed transcript 1) 27 , Thada (thyroid adenoma associated) 28 , Cmah 23 , 24 , and Chsy1 (chondroitin sulfate synthase 1) 29 (Supplementary Table S1 , S2 ).…”

“…Ninj2 was previously reported to contribute to neurite outgrowth and enhance growth, survival and proliferation of glioma and colorectal cancer cells 12 , 36 , 37 . Another candidate that survived, cell line #40, was characterised by RVI into the vicinity of the Chsy1 gene, which is involved in neutrophil and macrophage survival and differentiation 29 .

Figure 3 Selection and characterisation of H9M-ciMPs under stem cell maintaining conditions and doxycycline application.

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“…ON/OFF/re-ON experiments) under myelomonocytic conditions revealed selective H9M-ciMP survival and reversibility. Thus, five H9M-ciMP cell lines with RVIs into loci of Ninj2 12 (#1, 5), Vps45 / Otud7b 25 , 26 (#11), Plet1 27 (#12) or Chsy1 29 (#40) showed rapid restoration of exponential growth after DOX reapplication, which was related to slower differentiation after DOX removal and probably longer LIC preservation.…”

“…The insertional analysis identified a number of potential genes involved in cancerogenesis, immune response, differentiation and metabolism, which may potentially cooperate with Hoxa9/Meis1 in cell line establishment (Supplementary Table S2 ). Hypothesising that insertional dysregulation of these genes could contribute to H9M-ciMP survival/differentiation under suboptimal intrinsic and extrinsic conditions, we initially focused on eight H9M-ciMP cell lines that had RVIs in the loci of Ninj2 12 (#1, 5), Vps45/Otud7b 25 , 26 (#11), Plet1 27 / Thada 28 (#12), Cmah 24 (#24, 25, 29) and Chsy1 29 (#40) (Supplementary Table S1 , S2 ).…”

Identification of a 9‐gene prognostic signature for breast cancer

“…Syntaxin-binding protein 3 (STXBP3) is involved in fatty acid-induced insulin resistance in skeletal muscle cells. 25 In chronic lymphocytic leukemia, lipoprotein lipase can cooperate with STXBP3 to promote chronic lymphocytic leukemia cells apoptosis. 26 Protein kinase N2 (PKN2) is a serine…”