Regulation of Runx2 Accumulation and Its Consequences

Osteoblasts are bone-forming cells and therefore they are responsible of the synthesis of type I collagen, the main component of bone matrix. However, there is an apparent disconnect between the regulation of osteoblast differentiation and bone formation since the synthesis of Type I collagen precedes the expression of Runx2, the earliest determinant of osteoblast differentiation. Recently, genetic experiments in the mouse have revealed the existence of an unexpected cross-regulation between bone and other organs. In particular this body of work has highlighted the importance of osteoblasts as endocrine cells to regulate whole-body glucose homeostasis by secretion of a hormone, osteocalcin. However, the fundamental question of why bone regulates glucose homeostasis remained to be answered. Therefore, in my thesis, considering that bone is a metabolically demanding organ that constantly renews itself, I hypothesized that characterizing the connection between the need of glucose as a main nutrient in osteoblasts and bone development will provide a key to deeper understanding of why bone regulates glucose homeostasis. My work shows here that glucose uptake through GLUT1 in osteoblasts is needed for osteoblast differentiation by suppressing the AMPK-dependent activation by phosphorylation at S148 of Smurf1 that targets Runx2 for degradation. I also uncovered the mechanism of action of Smurf1 in this setting. In a distinct but synergetic way, glucose uptake promotes bone formation by inhibiting a distinct function of AMPK. In turn, Runx2 favors Glut1 expression, and this feedforward regulation between Runx2 and Glut1 determines the onset of osteoblast differentiation during development and the extent of bone formation throughout life. Furthermore, I also identified that Smurf1 not only regulates osteoblast differentiation by targeting Runx2 for degradation but also contributes to whole-body glucose homeostasis by regulating the activation of osteocalcin by targeting the insulin receptor for degradation in vivo. These results identify Smurf1 as a determinant of osteoblast differentiation during development, of bone formation and glucose homeostasis post-natally. Most importantly, we show that these Smurf1 functions required AMPK-phosphorylation site S148 in vivo. Altogether, these results revealed the absolute necessity of glucose as a regulator of Runx2 accumulation during osteoblast differentiation and bone formation in vivo and highlight the fundamental importance of the intricate cross-talk between bone and whole-body glucose metabolism

Loss of Catalytically Inactive Lipid Phosphatase Myotubularin-related Protein 12 Impairs Myotubularin Stability and Promotes Centronuclear Myopathy in Zebrafish

X-linked myotubular myopathy (XLMTM) is a congenital disorder caused by mutations of the myotubularin gene, MTM1. Myotubularin belongs to a large family of conserved lipid phosphatases that include both catalytically active and inactive myotubularin-related proteins (i.e., “MTMRs”). Biochemically, catalytically inactive MTMRs have been shown to form heteroligomers with active members within the myotubularin family through protein-protein interactions. However, the pathophysiological significance of catalytically inactive MTMRs remains unknown in muscle. By in vitro as well as in vivo studies, we have identified that catalytically inactive myotubularin-related protein 12 (MTMR12) binds to myotubularin in skeletal muscle. Knockdown of the mtmr12 gene in zebrafish resulted in skeletal muscle defects and impaired motor function. Analysis of mtmr12 morphant fish showed pathological changes with central nucleation, disorganized Triads, myofiber hypotrophy and whorled membrane structures similar to those seen in X-linked myotubular myopathy. Biochemical studies showed that deficiency of MTMR12 results in reduced levels of myotubularin protein in zebrafish and mammalian C2C12 cells. Loss of myotubularin also resulted in reduction of MTMR12 protein in C2C12 cells, mice and humans. Moreover, XLMTM mutations within the myotubularin interaction domain disrupted binding to MTMR12 in cell culture. Analysis of human XLMTM patient myotubes showed that mutations that disrupt the interaction between myotubularin and MTMR12 proteins result in reduction of both myotubularin and MTMR12. These studies strongly support the concept that interactions between myotubularin and MTMR12 are required for the stability of their functional protein complex in normal skeletal muscles. This work highlights an important physiological function of catalytically inactive phosphatases in the pathophysiology of myotubular myopathy and suggests a novel therapeutic approach through identification of drugs that could stabilize the myotubularin-MTMR12 complex and hence ameliorate this disorder

Comparison of weighed food record procedures for the reference methods in two validation studies of food frequency questionnaires

Background: Although open-ended dietary assessment methods, such as weighed food records (WFRs), are generally considered to be comparable, differences between procedures may influence outcome when WFRs are conducted independently. In this paper, we assess the procedures of WFRs in two studies to describe their dietary assessment procedures and compare the subsequent outcomes. Methods: WFRs of 12 days (3 days for four seasons) were conducted as reference methods for intake data, in accordance with the study protocol, among a subsample of participants of two large cohort studies. We compared the WFR procedures descriptively. We also compared some dietary intake variables, such as the frequency of foods and dishes and contributing foods, to determine whether there were differences in the portion size distribution and intra- and inter-individual variation in nutrient intakes caused by the difference in procedures. Results: General procedures of the dietary records were conducted in accordance with the National Health and Nutrition Survey and were the same for both studies. Differences were seen in 1) selection of multiple days (non-consecutive days versus consecutive days); and 2) survey sheet recording method (individual versus family participation). However, the foods contributing to intake of energy and selected nutrients, the portion size distribution, and intra- and inter-individual variation in nutrient intakes were similar between the two studies. Conclusion: Our comparison of WFR procedures in two independent studies revealed several differences. Notwithstanding these procedural differences, however, the subsequent outcomes were similar

Use of vitamin supplements and risk of total cancer and cardiovascular disease among the Japanese general population: A population-based survey

<p>Abstract</p> <p>Background</p> <p>Despite the popular use of vitamin supplements and several prospective cohort studies investigating their effect on cancer incidence and cardiovascular disease (CVD), scientific data supporting their benefits remain controversial. Inconsistent results may be partly explained by the fact that use of supplements is an inconsistent behavior in individuals. We examined whether vitamin supplement use patterns affect cancer and CVD risk in a population-based cohort study in Japan.</p> <p>Methods</p> <p>A total of 28,903 men and 33,726 women in the Japan Public Health Center-based Prospective Study cohort, who answered questions about vitamin supplement use in the first survey from 1990-1994 and the second survey from 1995-1998, were categorized into four groups (never use, past use, recent use, and consistent use) and followed to the end of 2006 for cancer and 2005 for CVD. Sex-specific hazard ratios (HRs) and 95% confidence intervals (95% CIs) were used to describe the relative risks of cancer and CVD associated with vitamin supplement use.</p> <p>Results</p> <p>During follow-up, 4501 cancer and 1858 CVD cases were identified. Multivariate adjusted analysis revealed no association of any pattern of vitamin supplement use with the risk of cancer and CVD in men. In women, consistent use was associated with lower risk of CVD (HR 0.60, 95% CI 0.41-0.89), whereas past (HR 1.17, 95% CI 1.02-1.33) and recent use (HR 1.24, 95% CI 1.01-1.52) were associated with higher risk of cancer.</p> <p>Conclusions</p> <p>To our knowledge, this is the first prospective cohort study to examine simultaneously the associations between vitamin supplement use patterns and risk of cancer and CVD. This prospective cohort study demonstrated that vitamin supplement use has little effect on the risk of cancer or CVD in men. In women, however, consistent vitamin supplement use might reduce the risk of CVD. Elevated risk of cancer associated with past and recent use of vitamin supplements in women may be partly explained by preexisting diseases or unhealthy background, but we could not totally control for this in our study.</p

Smurf1 Inhibits Osteoblast Differentiation, Bone Formation, and Glucose Homeostasis through Serine 148

The E3 ubiquitin ligase Smurf1 targets the master regulator of osteoblast differentiation, Runx2, for degradation, yet the function of Smurf1, if any, during osteoblast differentiation in vivo is ill defined. Here, we show that Smurf1 prevents osteoblast differentiation by decreasing Runx2 accumulation in osteoblasts. Remarkably, mice harboring a substitution mutation at serine 148 (S148) in Smurf1 that prevents its phosphorylation by AMPK (Smurf1ki/ki) display a premature osteoblast differentiation phenotype that is equally severe as that of Smurf1−/− mice, as well as a high bone mass, and are also hyperinsulinemic and hypoglycemic. Consistent with the fact that Smurf1 targets the insulin receptor for degradation, there is, in Smurf1ki/ki mice, an increase in insulin signaling in osteoblasts that triggers a rise in the circulating levels of osteocalcin, a hormone that favors insulin secretion. These results identify Smurf1 as a determinant of osteoblast differentiation during the development of bone formation and glucose homeostasis post-natally and demonstrate the necessity of S148 for these functions

Feasibility of a community-adapted multi-domain intervention for dementia prevention among older adults: a research protocol

Abstract Background Multi-domain interventions effectively prevent dementia in clinical settings; however, their efficacy within local communities is unclear. This study assesses the feasibility of an adapted multi-domain intervention for dementia prevention in community-dwelling older adults. Methods The single-arm trial enrolls 60 participants from two Obu City communities, Japan. Primary outcome: participant retention in the adapted multi-domain intervention; secondary outcomes: health and implementation outcomes. Over 12 months, a team of researchers and public health nurse oversees the study in the first half, gradually shifting the management to public health nurses in the second half. Using the Framework for Reporting Adaptations and Modifications-Enhanced, the clinical programme is adjusted for the local community. It includes a 60-minute exercise and 30-minute group sessions, targeting lifestyle, diet, and social participation. Discussion This pioneer study evaluates the feasibility of an adapted intervention programme for dementia prevention in a community setting. Challenges in disseminating dementia prevention programmes warrant further investigation into effective implementation as well as strategies and methods to appeal to the target population. Upon confirming this programme’s feasibility, future studies can further evaluate its broader effectiveness. Trial registration The protocol is registered with the Clinical Trials Registry (UMIN-CTR) of the University Hospital’s Medical Information Network, under registration number UMIN000050581

Smoking cessation interventions and implementations across multiple settings in Japan: a scoping review and supplemental survey

Abstract Background Smoking is the leading risk factor for death worldwide. In Japan, although several evidence-based interventions (EBIs) for smoking cessation have been disseminated or adopted, there is a gap between scientific evidence and the actual implementation. This scoping review aimed to describe the knowledge gaps in local-level smoking cessation interventions in Japan, their implementation outcomes, implementation barriers and facilitators, and the use of implementation strategies. Methods This study comprised two approaches: (1) a comprehensive scoping review of primary and grey literature, and (2) a supplemental survey of organizations in the grey literature. For the scoping review, we included original studies or reports on smoking cessation interventions targeting adults aged 18 years and older, or providers of cessation support at various settings (community, workplace, school, and clinical settings) in Japan. The extracted data included basic characteristics, intervention categories, implementation outcomes, factors influencing implementation, and implementation strategies for each intervention. Responses to the supplemental survey were extracted same used for the scoping review. To gain a deeper understanding, semi-structured interviews were conducted with some of the organizations in the survey. Results A total of 600 interventions with 691 intervention components, based on EBIs in the 2020 US Surgeon General Report, from 498 articles were included in the data extraction; 32 of the 88 organizations responded to the survey. Regarding the overall knowledge about smoking cessation intervention components, behavioral counseling, and cessation medication in clinical settings were mostly reported (34.7%). Implementation outcomes were measured in 18 articles (3.0%) and penetration was mostly reported. Regarding influential factors, “available resources,” and “knowledge and beliefs about the intervention” for barriers, and “relative priority” for facilitators were mostly reported. Implementation strategies were measured in 29 articles (4.8%), and “Train and educate stakeholders” was mostly reported. Conclusions Most EBIs reported in the Japanese literature included smoking cessation treatments in clinical settings. While a few articles focused on the implementation indicators in Japan, significant knowledge and experience were extracted from the grey literature, especially in the workplace and community settings. Future research should focus more on implementation to reduce the knowledge gap regarding smoking cessation interventions