JRAB/MICAL-L2 undergoes liquid–liquid phase separation to form tubular recycling endosomes

Elongated tubular endosomes play essential roles in diverse cellular functions. Multiple molecules have been implicated in tubulation of recycling endosomes, but the mechanism of endosomal tubule biogenesis has remained unclear. In this study, we found that JRAB/MICAL-L2 induces endosomal tubulation via activated Rab8A. In association with Rab8A, JRAB/MICAL-L2 adopts its closed form, which functions in the tubulation of recycling endosomes. Moreover, JRAB/MICAL-L2 induces liquid–liquid phase separation, initiating the formation of tubular recycling endosomes upon overexpression. Between its N-terminal and C-terminal globular domains, JRAB/MICAL-L2 contains an intrinsically disordered region, which contributes to the formation of JRAB/MICAL-L2 condensates. Based on our findings, we propose that JRAB/MICAL-L2 plays two sequential roles in the biogenesis of tubular recycling endosomes: first, JRAB/MICAL-L2 organizes phase separation, and then the closed form of JRAB/MICAL-L2 formed by interaction with Rab8A promotes endosomal tubulation

分子内結合が調節するJRABのLIMドメインによるアクチン細胞骨格の再編成

JRAB/MICAL-L2 is an effector protein of Rab13, a member of the Rab family of small GTPase. JRAB/MICAL-L2 consists of a calponin homology domain, a LIM domain, and a coiled-coil domain. JRAB/MICAL-L2 engages in intramolecular interaction between the N-terminal LIM domain and the C-terminal coiled-coil domain, and changes its conformation from closed to open under the effect of Rab13. Open-form JRAB/MICAL-L2 induces the formation of peripheral ruffles via an interaction between its calponin homology domain and filamin. Here, we report that the LIM domain, independent of the C-terminus, is also necessary for the function of open-form JRAB/MICAL-L2. In mechanistic terms, two zinc finger domains within the LIM domain bind the first and second molecules of actin at the minus end, potentially inhibiting the depolymerization of actin filaments (F-actin). The first zinc finger domain also contributes to the intramolecular interaction of JRAB/MICAL-L2. Moreover, the residues of the first zinc finger domain that are responsible for the intramolecular interaction are also involved in the association with F-actin. Together, our findings show that the function of open-form JRAB/MICAL-L2 mediated by the LIM domain is fine-tuned by the intramolecular interaction between the first zinc finger domain and the C-terminal domain

Functionally confirmed compound heterozygous ADAM17 missense loss-of-function variants cause neonatal inflammatory skin and bowel disease 1

A disintegrin and metalloprotease 17 (ADAM17) is the major sheddase that processes more than 80 substrates, including tumour necrosis factor-α (TNFα). The homozygous genetic deficiency of ADAM17 causing a complete loss of ADAM17 expression was reported to be linked to neonatal inflammatory skin and bowel disease 1 (NISBD1). Here we report for the first time, a family with NISBD1 caused by functionally confirmed compound heterozygous missense variants of ADAM17, namely c.1699T>C (p.Cys567Arg) and c.1799G>A (p.Cys600Tyr). Both variants were detected in two siblings with clinical features of NISBD1, such as erythroderma with exudate in whole body, recurrent skin infection and sepsis and prolonged diarrhoea. In a cell-based assay using Adam10/17 double-knockout mouse embryonic fibroblasts (Adam10/17−/− mEFs) exogenously expressing each of these mutants, phorbol 12-myristate 13-acetate-stimulated shedding was strongly reduced compared with wild-type ADAM17. Thus, in vitro functional assays demonstrated that both missense variants cause the loss-of-function of ADAM17, resulting in the development of NISBD1. Our study further expands the spectrum of genetic pathology underlying ADAM17 in NISBD1 and establishes functional assay systems for its missense variants

JRAB shifts “dancing style” of cell clusters

In fundamental biological processes, cells often move in groups, a process termed collective cell migration. Collectively migrating cells are much better organized than a random assemblage of individual cells. Many molecules have been identified as factors involved in collective cell migration, and no one molecule is adequate to explain the whole picture. Here we show that JRAB/MICAL-L2, an effector protein of Rab13 GTPase, provides the “law and order” allowing myriad cells to behave as a single unit just by changing its conformation. First, we generated a structural model of JRAB/MICAL-L2 by a combination of bioinformatic and biochemical analyses and showed how JRAB/MICAL-L2 interacts with Rab13 and how its conformational change occurs. We combined cell biology, live imaging, computational biology, and biomechanics to show that impairment of conformational plasticity in JRAB/MICAL-L2 causes excessive rigidity and loss of directionality, leading to imbalance in cell group behavior. This multidisciplinary approach supports the concept that the conformational plasticity of a single molecule provides “law and order” in collective cell migration

Attitudes toward and current status of disclosure of secondary findings from next-generation sequencing: a nation-wide survey of clinical genetics professionals in Japan

The management of secondary findings (SFs), which are beyond the intended purpose of the analysis, from clinical comprehensive genomic analysis using next generation sequencing (NGS) presents challenges. Policy statements regarding their clinical management have been announced in Japan and other countries. In Japan, however, the current status of and attitudes of clinical genetics professionals toward reporting them are unclear. We conducted a questionnaire survey of clinical genetics professionals at two time points (2013 and 2019) to determine the enforcement of the SF management policy in cases of comprehensive genetic analysis of intractable diseases and clinical cancer genome profiling testing. According to the survey findings, 40% and 70% of the respondents stated in the 2013 and 2019 surveys, respectively, that they had an SF policy in the field of intractable diseases, indicating that SF policy awareness in Japan has changed significantly in recent years. Furthermore, a total of 80% of respondents stated that their facility had established a policy for clinical cancer genome profiling testing in the 2019 survey. In both surveys, the policies included the selection criteria for genes to be disclosed and the procedure to return SFs, followed by recommendations and proposals regarding SFs in Japan and other countries. To create a better list of the genes to be disclosed, further examination is needed considering the characteristics of each analysis

Application of layered poly (L-lactic acid) cell free scaffold in a rabbit rotator cuff defect model

<p>Abstract</p> <p>Background</p> <p>This study evaluated the application of a layered cell free poly (L-lactic acid) (PLLA) scaffold to regenerate an infraspinatus tendon defect in a rabbit model. We hypothesized that PLLA scaffold without cultivated cells would lead to regeneration of tissue with mechanical properties similar to reattached infraspinatus without tendon defects.</p> <p>Methods</p> <p>Layered PLLA fabric with a smooth surface on one side and a pile-finished surface on the other side was used. Novel form of layered PLLA scaffold was created by superimposing 2 PLLA fabrics. Defects of the infraspinatus tendon were created in 32 rabbits and the PLLA scaffolds were transplanted, four rabbits were used as normal control. Contralateral infraspinatus tendons were reattached to humeral head without scaffold implantation. Histological and mechanical evaluations were performed at 4, 8, and 16 weeks after operation.</p> <p>Results</p> <p>At 4 weeks postoperatively, cell migration was observed in the interstice of the PLLA fibers. Regenerated tissue was directly connected to the bone composed mainly of type III collagen, at 16 weeks postoperatively. The ultimate failure load increased in a time-dependent manner and no statistical difference was seen between normal infraspinatus tendon and scaffold group at 8 and 16 weeks postoperatively. There were no differences between scaffold group and reattach group at each time of point. The stiffness did not improve significantly in both groups.</p> <p>Conclusions</p> <p>A novel form of layered PLLA scaffold has the potential to induce cell migration into the scaffold and to bridge the tendon defect with mechanical properties similar to reattached infraspinatus tendon model.</p

A Cluster of Respiratory Syncytial Virus Infections in a Hospital Ward for Adult Immunocompromised Patients

Four male patients admitted to the same ward in the first half of September 201Y were identified to have respiratory syncytial virus（RSV）infection. Their ages ranged from 49 to 85 years（median 72.5）. One patient was infected with human immunodeficiency virus and three patients had hematological malignancies. Following immuno-chromatological testing with a nasal cavity swab, RSV infection was diagnosed. Although blood and sputum cultures were performed in three patients, no significant bacteria were detected. Two cases responded to supportive therapy. However, one patient died secondary to multiple myeloma, and another patient developed pneumonia and died with an exacerbation of leukemia. RSV infections in immunocompromised hosts are associated with a poor prognosis. Early diagnosis will facilitate isolation of infected individuals to prevent hospital outbreaks

Ketone bodies : A double-edged sword for mammalian life span.

Accumulating evidence suggests health benefits of ketone bodies, and especially for longevity. However, the precise role of endogenous ketogenesis in mammalian life span, and the safety and efficacy of the long-term exogenous supplementation of ketone bodies remain unclear. In the present study, we show that a deficiency in endogenous ketogenesis, induced by whole-body Hmgcs2 deletion, shortens life span in mice, and that this is prevented by daily ketone body supplementation using a diet containing 1,3-butanediol, a precursor of β-hydroxybutyrate. Furthermore, feeding the 1,3-butanediol-containing diet from early in life increases midlife mortality in normal mice, but in aged mice it extends life span and prevents the high mortality associated with atherosclerosis in ApoE-deficient mice. By contrast, an ad libitum low-carbohydrate ketogenic diet markedly increases mortality. In conclusion, endogenous ketogenesis affects mammalian survival, and ketone body supplementation may represent a double-edged sword with respect to survival, depending on the method of administration and health status

緊張性振動反射が動作学習に与える影響 : 脳血管障害患者の肘関節伸展動作に着目して

本研究は脳血管障害患者8名を対象に麻痺側肘関節伸展動作の介入時に、緊張性振動反射（Tonic Vibration Reflex; TVR）を用いる事での動作学習への効果とその持続時間について明らかにする事を目的とした。研究デザインはクロスオーバー比較試験であり、条件①（肘関節屈曲伸展動作を自動運動で30回実施する条件）、条件②（条件①実施の際、肘関節伸展時に上腕三頭筋へのTVR を与えて実施する条件）の2条件である。各介入5、10分後にactive-ROMを測定して効果を検討した。介入5分後では両群共に条件②が条件①よりも有意に肘関節伸展角度が大きかった。介入10分後では両群共に条件間で有意差を示さなかった。このことからTVRを用いた機能的介入は即時効果としての促通効果に繋がる一方で、長期的な効果は認められなかった。これは本研究での介入期間が短すぎたことから、運動段階での内在的Feedbackに繋がらなかった事で忘却したものと考えられたThe purpose of this study was to examine effective use of TVR（Tonic Vibration Reflex） in motor training. Research Condition 1： The first condition consists of extending and flexing of a test subject\u27s elbow joint 30times without the use of TVR with a range of motion test of five and ten minutes. Research Condition 2： The second condition consists of using TVR on the triceps of the test subject\u27s elbow joint before extending and flexing the test subject\u27s elbow joint again 30times with a range of motion test of five and ten minutes. Results： After completing both tests, results shows that there is a significant and visible difference of the extension angle of the elbow joint while using TVR during the first five minutes of testing with both research conditions. However, there was not any significant or visible difference after the use of TVR after the ten minutes intervals of testing. Conclusion： TVR has an immediate effect in motor training. However, the TVR effect is only for a short amount of time. The possible reason for these results may be the short amount of time that was used to conduct the testing