PLEIAD/SIMC1/C5orf25, a Novel Autolysis Regulator for a Skeletal-Muscle-Specific Calpain, CAPN3, Scaffolds a CAPN3 Substrate, CTBP1

AbstractCAPN3/p94/calpain-3 is a skeletal-muscle-specific member of the calpain protease family. Multiple muscle cell functions have been reported for CAPN3, and mutations in this protease cause limb-girdle muscular dystrophy type 2A. Little is known about the molecular mechanisms that allow CAPN3 to be so multifunctional. One hypothesis is that the very rapid and exhaustive autolytic activity of CAPN3 needs to be suppressed by dynamic molecular interactions for specific periods of time. The previously identified interaction between CAPN3 and connectin/titin, a giant molecule in muscle sarcomeres, supports this assumption; however, the regulatory mechanisms of non-sarcomere-associated CAPN3 are unknown. Here, we report that a novel CAPN3-binding protein, PLEIAD [Platform element for inhibition of autolytic degradation; originally called SIMC1/C5orf25 (SUMO-interacting motif containing protein 1/chromosome 5 open reading frame 25)], suppresses the protease activity of CAPN3. Database analyses showed that PLEIAD homologs, like CAPN3 homologs, are evolutionarily conserved in vertebrates. Furthermore, we found that PLEIAD also interacts with CTBP1 (C-terminal binding protein 1), a transcriptional co-regulator, and CTBP1 is proteolyzed in COS7 cells expressing CAPN3. The identified cleavage sites in CTBP1 suggested that it undergoes functional modification upon its proteolysis by CAPN3, as well as by conventional calpains. These results indicate that PLEIAD can shift its major function from CAPN3 suppression to CAPN3-substrate recruitment, depending on the cellular context. Taken together, our data suggest that PLEIAD is a novel regulatory scaffold for CAPN3, as reflected in its name

Need for Flexible Adjustment of the Treatment Schedule for Aprepitant Administration against Erlotinib-Induced Refractory Pruritus and Skin Rush

Common dermatological side-effects associated with erlotinib, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI), include pruritus and skin rash, which are mediated by substance P, leading to the occasional discontinuation of cancer treatment. Aprepitant is an antagonist of neurokinin-1 receptor, through which substance P activates the pruritogens. Thus, aprepitant is expected to offer a promising option for the treatment of erlotinib-induced pruritus. However, the appropriate treatment schedule for aprepitant administration is under consideration. Here, we discuss the need for flexible adjustment of the treatment schedule for aprepitant administration against erlotinib-induced refractory pruritus and skin rush. A 71-year-old female smoker presented with stage IV EGFR-mutated lung adenocarcinoma. She was started on erlotinib at 150 mg/day. However, by 28 days, severe pruritus and acneiform skin rush resistant to standard therapies occurred, resulting in the interruption of erlotinib therapy. After recovery, she was restarted on erlotinib at 100 mg/day. However, severe pruritus and skin rush developed again within 2 weeks. Then, we started the first 3-day dose of aprepitant (125 mg on day 1, 80 mg on day 3, and 80 mg on day 5) based on the results of the previous prospective study, which showed the success rate of 100% with at least the second dose of aprepitant. However, the pruritus and skin rush exacerbated again within 4 weeks. Therefore, we started the second 3-day dose of aprepitant, but in vain. At this point, as the patient-centered medicine, bi-weekly schedule of the 3-day dose of aprepitant was considered and, then, adopted. As the results, the pruritus and skin rush remained well-controlled throughout the subsequent treatment with erlotinib

Detection of Transgenes in Gene Delivery Model Mice by Adenoviral Vector Using ddPCR

With the rapid progress of genetic engineering and gene therapy, the World Anti-Doping Agency has been alerted to gene doping and prohibited its use in sports. However, there is no standard method available yet for the detection of transgenes delivered by recombinant adenoviral (rAdV) vectors. Here, we aim to develop a detection method for transgenes delivered by rAdV vectors in a mouse model that mimics gene doping. These rAdV vectors containing the mCherry gene was delivered in mice through intravenous injection or local muscular injection. After five days, stool and whole blood samples were collected, and total DNA was extracted. As additional experiments, whole blood was also collected from the mouse tail tip until 15 days from injection of the rAdv vector. Transgene fragments from different DNA samples were analyzed using semi-quantitative PCR (sqPCR), quantitative PCR (qPCR), and droplet digital PCR (ddPCR). In the results, transgene fragments could be directly detected from blood cell fraction DNA, plasma cell-free DNA, and stool DNA by qPCR and ddPCR, depending on specimen type and injection methods. We observed that a combination of blood cell fraction DNA and ddPCR was more sensitive than other combinations used in this model. These results could accelerate the development of detection methods for gene doping

Disruption of Tacc3 function leads to in vivo tumor regression

The formation of the bipolar spindle is responsible for accurate chromosomal segregation during mitosis. The dynamic instability of microtubules has an important role in this process, and has been shown to be an effective target for cancer chemotherapy. Several agents that target non-microtubule mitotic proteins, including the motor protein Eg5, Aurora kinases and Polo-like kinases, are currently being developed as chemotherapeutic drugs. However, because the efficacies of these drugs remain elusive, new molecular targets that have essential roles in tumor cells are desired. Here, we provide in vivo evidence that transforming acidic coiled-coil-3 (Tacc3) is a potential target for cancer chemotherapy. Using MRI, we showed that Tacc3 loss led to the regression of mouse thymic lymphoma in vivo, which was accompanied by massive apoptosis. By contrast, normal tissues, including the thymus, showed no overt abnormalities, despite high Tacc3 expression. in vitro analysis indicated that Tacc3 depletion induced multi-polar spindle formation, which led to mitotic arrest, followed by apoptosis. Similar responses have been observed in Burkitt\u27s lymphoma and T-ALL. These results show that Tacc3 is a vulnerable component of the spindle assembly in lymphoma cells and is a promising cancer chemotherapy targe