Mechanism Underlying IKK Activation Mediated by the Linear Ubiquitin Chain Assembly Complex (LUBAC)

The linear ubiquitin chain assembly complex (LUBAC) ligase, consisting of HOIL-1L, HOIP, and SHARPIN, specifically generates linear polyubiquitin chains. LUBAC-mediated linear polyubiquitination has been implicated in NF-κB activation. NEMO, a component of the IκB kinase (IKK) complex, is a substrate of LUBAC, but the precise molecular mechanism underlying linear chain-mediated NF-κB activation has not been fully elucidated. Here, we demonstrate that linearly polyubiquitinated NEMO activates IKK more potently than unanchored linear chains. In mutational analyses based on the crystal structure of the complex between the HOIP NZF1 and NEMO CC2-LZ domains, which are involved in the HOIP-NEMO interaction, NEMO mutations that impaired linear ubiquitin recognition activity and prevented recognition by LUBAC synergistically suppressed signal-induced NF-κB activation. HOIP NZF1 bound to NEMO and ubiquitin simultaneously, and HOIP NZF1 mutants defective in interaction with either NEMO or ubiquitin could not restore signal-induced NF-κB activation. Furthermore, linear chain-mediated activation of IKK2 involved homotypic interaction of the IKK2 kinase domain. Collectively, these results demonstrate that linear polyubiquitination of NEMO plays crucial roles in IKK activation and that this modification involves the HOIP NZF1 domain and recognition of NEMO-conjugated linear ubiquitin chains by NEMO on another IKK complex

Gab1 and Mapk Signaling Are Essential in the Hair Cycle and Hair Follicle Stem Cell Quiescence

SummaryGab1 is a scaffold protein that acts downstream of receptor tyrosine kinases. Here, we produced conditional Gab1 mutant mice (by K14- and Krox20-cre) and show that Gab1 mediates crucial signals in the control of both the hair cycle and the self-renewal of hair follicle stem cells. Remarkably, mutant hair follicles do not enter catagen, the destructive phase of the hair cycle. Instead, hair follicle stem cells lose quiescence and become exhausted, and thus no stem cell niches are established in the bulges. Moreover, conditional sustained activation of Mapk signaling by expression of a gain-of-function Mek1DD allele (by Krox20-cre) rescues hair cycle deficits and restores quiescence of the stem cells. Our data thus demonstrate an essential role of Gab1 downstream of receptor tyrosine kinases and upstream of Shp2 and Mapk in the regulation of the hair cycle and the self-renewal of hair follicle stem cells

Ureteral stent replacement in women

Purpose : To evaluate the efficacy of the direct grasping technique using pean forceps under fluoroscopic guidance for ureteral stent replacement in women. Methods : Between April 2018 and September 2020, 28 female patients underwent ureteral stent replacements at our facility, and 184 stent replacement procedures were performed. A total of 127 stents were replaced using pean forceps under fluoroscopic guidance (pean forceps group), and 57 stents were replaced using the cystoscope (cystoscopy group). Clinical characteristics and surgical outcomes were compared between the groups. Results : All stents were successfully replaced. There was a statistically significant difference in the procedure time between the two groups (median [interquartile range], pean forceps group : 10.8 [8.2–13.9] minutes vs. cystoscopy group : 15.8 [11.1–20.9] minutes, P < 0.001). There were no intraoperative complications in either group and no difference in the incidence of postoperative complications (pean forceps group : 1.6% vs. cystoscopy group : 1.8%, P = 1.000). Fluoroscopy time was longer in the pean forceps group, although this difference was not statistically significant (pean forceps group : 38.9 [22.6–60.1] seconds vs. cystoscopy group : 33.0 [20.0–48.9] seconds, P = 0.0558). Conclusion : The direct grasping technique using pean forceps under fluoroscopy may be a beneficial alternative to cystoscopy for ureteral stent replacement in women

Early urinary catheter removal in stroke

Objective : The aim of the present study was to identify factors related to the success of trial without catheter (TWOC) in patients with stroke and to examine the effect of the timing of urinary catheter removal on the course of stroke. Methods : Patients who were admitted to the Stroke Care Unit of our institution between March 2018 and October 2021 were included. To identify factors related to success of TWOC, a multivariate analysis was performed on the patient’s condition at admission and catheter indwelling time. The patients were divided into two groups by the timing of catheter removal, and we assessed the relationship between the timing of catheter removal successful TWOC and recovery of physical function. Results : A total of 118 patients were included. The presence of comorbidities and scores of severity and function at admission were not predictors of successful voiding. The time to achieve voiding sussess was significantly shorter in the early catheter removal group than in the later group (p < 0.005). Interestingly, the early group also showed better improvements in physical function. Conclusion : Early removal of catheters may lead to early recovery of bladder function, improvement of physical function, and lower risk of complications in patients with stroke

Impact of body composition on mRCC Prognosis

Purpose : This study aimed to analyze the impact of patients’ nutritional status and changes in body composition on the prognosis of metastatic renal cell carcinoma (mRCC) patients who received systemic therapy with tyrosine kinase inhibitors (TKIs). Methods : A total of 57 mRCC patients who received systemic therapy with TKIs as first-line therapy at our facility between November 2004 and October 2018 were included. The Prognostic Nutritional Index (PNI) was used to evaluate their nutritional status. The volumes of skeletal muscle mass and fat tissue were calculated using the SYNAPSE VINCENT system. The effects of nutritional status and body composition of mRCC patients on progression-free survival (PFS) and overall survival (OS) were analyzed using Cox regression methods. Results : Low PNI at the start of systemic therapy was a significant prognostic predictor for OS (HR 3.807 [95% CI 1.205-12.027], P = 0.046), and it was related to loss of muscle mass three months after systemic therapy. Although the loss of muscle mass at the start of systemic therapy was not associated with OS, loss of muscle mass during treatment predicted worse OS. Conclusions : Nutritional status of mRCC patients may predict changes in body composition and be associated with their prognosis

MYC is essential for the formation and maintenance of germinal centers

Germinal centers (GC) are sites of intense B cell proliferation, central for T cell dependent antibody responses. However, the role of MYC, a key cell cycle regulator, in this process has been questioned. Here, we identified MYC positive B cell subpopulations in immature and mature GCs, and show through genetic ablation of Myc that they play indispensable roles in GC formation and maintenance. The identification of these functionally critical cellular subsets has important implications for human B cell lymphomagenesis, which mostly originates from GC B cells and frequently involves MYC chromosomal translocations. As these translocations are generally dependent on transcription of the recombining partner loci, the MYC positive GC subpopulations may be at a particularly high risk for malignant transformation

成熟T細胞の生存はHOIPを介するシグナルに依存する

T cell development in the thymus is controlled by a multistep process. The NF-κB pathway regulates T cell development as well as T cell activation at multiple differentiation stages. The linear ubiquitin chain assembly complex (LUBAC) is composed of Sharpin, HOIL-1L and HOIP, and it is crucial for regulating the NF-κB and cell death pathways. However, little is known about the roles of LUBAC in T-cell development and activation. Here, we show that in T-HOIPΔlinear mice lacking the ubiquitin ligase activity of LUBAC, thymic CD4+ or CD8+ T cell numbers were markedly reduced with severe defects in NKT cell development. HOIPΔlinear CD4+ T cells failed to phosphorylate IκBα and JNK through T cell receptor-mediated stimulation. Mature CD4+ and CD8+ T cells in T-HOIPΔlinear mice underwent apoptosis more rapidly than control T cells, and it was accompanied by lower CD127 expression on CD4+CD24low and CD8+CD24low T cells in the thymus. The enforced expression of CD127 in T-HOIPΔlinear thymocytes rescued the development of mature CD8+ T cells. Collectively, our results showed that LUBAC ligase activity is key for the survival of mature T cells, and suggest multiple roles of the NF-κB and cell death pathways in activating or maintaining T cell-mediated adaptive immune responses

IgG1 B cell receptor signaling is inhibited by CD22 and promotes the development of B cells whose survival is less dependent on Igα/β

We describe a mouse strain in which B cell development relies either on the expression of membrane-bound immunoglobulin (Ig) γ1 or μ heavy chains. Progenitor cells expressing γ1 chains from the beginning generate a peripheral B cell compartment of normal size with all subsets, but a partial block is seen at the pro– to pre–B cell transition. Accordingly, γ1-driven B cell development is disfavored in competition with developing B cells expressing a wild-type (WT) IgH locus. However, the mutant B cells display a long half-life and accumulate in the mature B cell compartment, and even though partial truncation of the Igα cytoplasmic tail compromises their development, it does not affect their maintenance, as it does in WT cells. IgG1-expressing B cells showed an enhanced Ca2+ response upon B cell receptor cross-linking, which was not due to a lack of inhibition by CD22. The enhanced Ca2+ response was also observed in mature B cells that had been switched from IgM to IgG1 expression in vivo. Collectively, these results suggest that the γ1 chain can exert a unique signaling function that can partially replace that of the Igα/β heterodimer in B cell maintenance and may contribute to memory B cell physiology

A propensity score matching study on robot-assisted radical cystectomy for older patients : comparison of intracorporeal ileal conduit and cutaneous ureterostomy

Background: Robot-assisted radical cystectomy (RARC) and intracorporeal urinary diversion are less invasive than conventional procedures. However, for older patients, cutaneous ureterostomy (CUS) may be preferred because urinary diversion using the intestine has a high incidence of perioperative complications and is highly invasive. The purpose of this study was to demonstrate the safety and efficacy of intracorporeal ileal conduit (ICIC) compared with CUS in patients aged 75 years or older who underwent RARC. Methods: From October 2014 to December 2021, 82 patients aged 75 years or older who underwent RARC at Tokushima University Hospital, Tokushima Prefectural Central Hospital, or Ehime Prefectural Central Hospital were retrospectively reviewed. Of these, 52 and 25 patients who underwent ICIC and CUS, respectively, were included. After adjusting the patients’ characteristics using propensity score-matching, surgical results and prognoses were retrospectively compared. The propensity score was based on age, Eastern Cooperative Oncology Group Performance Status Scale (ECOG-PS), American Society of Anesthesiologists physical status classification (ASA-PS), clinical tumor stage, and neoadjuvant chemotherapy. Results: The median age was lower in the ICIC group compared with the CUS group, and the proportion of high-risk cases (ECOG-PS ≥ 2 or ASA-PS ≥ 3) did not differ. The median operation time was longer in the ICIC group, and estimated blood loss was higher, compared with the CUS group. There were no significant differences in the incidence of complications within the first 30 postoperative days, incidence of complications 30–90 days after surgery, 2 year overall survival, 2-year cancer-specific survival, and 2-year recurrence-free survival. The stent-free rate was significantly lower in the CUS group than that in the ICIC group. Conclusion: In older patients, the ICIC group showed non-inferior surgical and oncological outcomes compared with the CUS group. Urinary diversion following RARC in older patients should be carefully selected by considering not only the age but also the general condition (including comorbidities) of the patient