Cellular adaptation to hypoxia through hypoxia inducible factors and beyond.

Molecular oxygen (O2) sustains intracellular bioenergetics and is consumed by numerous biochemical reactions, making it essential for most species on Earth. Accordingly, decreased oxygen concentration (hypoxia) is a major stressor that generally subverts life of aerobic species and is a prominent feature of pathological states encountered in bacterial infection, inflammation, wounds, cardiovascular defects and cancer. Therefore, key adaptive mechanisms to cope with hypoxia have evolved in mammals. Systemically, these adaptations include increased ventilation, cardiac output, blood vessel growth and circulating red blood cell numbers. On a cellular level, ATP-consuming reactions are suppressed, and metabolism is altered until oxygen homeostasis is restored. A critical question is how mammalian cells sense oxygen levels to coordinate diverse biological outputs during hypoxia. The best-studied mechanism of response to hypoxia involves hypoxia inducible factors (HIFs), which are stabilized by low oxygen availability and control the expression of a multitude of genes, including those involved in cell survival, angiogenesis, glycolysis and invasion/metastasis. Importantly, changes in oxygen can also be sensed via other stress pathways as well as changes in metabolite levels and the generation of reactive oxygen species by mitochondria. Collectively, this leads to cellular adaptations of protein synthesis, energy metabolism, mitochondrial respiration, lipid and carbon metabolism as well as nutrient acquisition. These mechanisms are integral inputs into fine-tuning the responses to hypoxic stress.

Opposing effects of TIGAR- and RAC1-derived ROS on Wnt-driven proliferation in the mouse intestine.

Reactive oxygen species (ROS) participate in numerous cell responses, including proliferation, DNA damage, and cell death. Based on these disparate activities, both promotion and inhibition of ROS have been proposed for cancer therapy. However, how the ROS response is determined is not clear. We examined the activities of ROS in a model of Apc deletion, where loss of the Wnt target gene Myc both rescues APC loss and prevents ROS accumulation. Following APC loss, Myc has been shown to up-regulate RAC1 to promote proliferative ROS through NADPH oxidase (NOX). However, APC loss also increased the expression of TIGAR, which functions to limit ROS. To explore this paradox, we used three-dimensional (3D) cultures and in vivo models to show that deletion of TIGAR increased ROS damage and inhibited proliferation. These responses were suppressed by limiting damaging ROS but enhanced by lowering proproliferative NOX-derived ROS. Despite having opposing effects on ROS levels, loss of TIGAR and RAC1 cooperated to suppress intestinal proliferation following APC loss. Our results indicate that the pro- and anti-proliferative effects of ROS can be independently modulated in the same cell, with two key targets in the Wnt pathway functioning to integrate the different ROS signals for optimal cell proliferation.

Corrigendum: Modulating the therapeutic response of tumours to dietary serine and glycine starvation.

This corrects the article DOI: 10.1038/nature22056.

Modulating the therapeutic response of tumours to dietary serine and glycine starvation.

The non-essential amino acids serine and glycine are used in multiple anabolic processes that support cancer cell growth and proliferation (reviewed in ref. 1). While some cancer cells upregulate de novo serine synthesis, many others rely on exogenous serine for optimal growth. Restriction of dietary serine and glycine can reduce tumour growth in xenograft and allograft models. Here we show that this observation translates into more clinically relevant autochthonous tumours in genetically engineered mouse models of intestinal cancer (driven by Apc inactivation) or lymphoma (driven by Myc activation). The increased survival following dietary restriction of serine and glycine in these models was further improved by antagonizing the anti-oxidant response. Disruption of mitochondrial oxidative phosphorylation (using biguanides) led to a complex response that could improve or impede the anti-tumour effect of serine and glycine starvation. Notably, Kras-driven mouse models of pancreatic and intestinal cancers were less responsive to depletion of serine and glycine, reflecting an ability of activated Kras to increase the expression of enzymes that are part of the serine synthesis pathway and thus promote de novo serine synthesis.

The intermediate-activity (L597V)BRAF mutant acts as an epistatic modifier of oncogenic RAS by enhancing signaling through the RAF/MEK/ERK pathway.

(L597V)BRAF mutations are acquired somatically in human cancer samples and are frequently coincident with RAS mutations. Germline (L597V)BRAF mutations are also found in several autosomal dominant developmental conditions known as RASopathies, raising the important question of how the same mutation can contribute to both pathologies. Using a conditional knock-in mouse model, we show that endogenous expression of (L597V)Braf leads to approximately twofold elevated Braf kinase activity and weak activation of the Mek/Erk pathway. This is associated with induction of RASopathy hallmarks including cardiac abnormalities and facial dysmorphia but is not sufficient for tumor formation. We combined (L597V)Braf with (G12D)Kras and found that (L597V)Braf modified (G12D)Kras oncogenesis such that fibroblast transformation and lung tumor development were more reminiscent of that driven by the high-activity (V600E)Braf mutant. Mek/Erk activation levels were comparable with those driven by (V600E)Braf in the double-mutant cells, and the gene expression signature was more similar to that induced by (V600E)Braf than (G12D)Kras. However, unlike (V600E)Braf, Mek/Erk pathway activation was mediated by both Craf and Braf, and ATP-competitive RAF inhibitors induced paradoxical Mek/Erk pathway activation. Our data show that weak activation of the Mek/Erk pathway underpins RASopathies, but in cancer, (L597V)Braf epistatically modifies the transforming effects of driver oncogenes.

Challenges of Diabetes Care in Older People With Type 2 Diabetes and the Role of Basal Insulin.

IN BRIEF The use of long-acting basal insulin analogs is a recommended strategy in older people with diabetes because of their lower risk of hypoglycemia compared to intermediate-acting insulins. In this article, we review the results from recent clinical trials of second-generation basal insulin preparations. We conclude that, although these preparations have improved the management of insulin-requiring older people with type 2 diabetes, there is a need for additional and more specific studies to address the complexities of hyperglycemia management in this population.

Occupational Therapist-Delivered Cognitive-Behavioral Therapy for Knee Osteoarthritis: A Randomized Pilot Study.

OBJECTIVE: This study assessed the feasibility and preliminary efficacy of an online-assisted, occupational therapist-delivered, cognitive-behavioral therapy intervention to promote physical function in patients with knee osteoarthritis (KOA). METHOD: Fifty-seven participants with KOA were randomized 2:1 to the Engage program (eight clinic-based sessions supported by online modules) or usual care. Using analysis of covariance, we estimated Engage's effect on physical function (Western Ontario and McMaster Universities Osteoarthritis Index's Physical Function subscale [WOMAC-PF]) at 6 mo. RESULTS: Data were analyzed on 46 completers. Engage was associated with a small effect (η² = 0.01) on the WOMAC-PF. More Engage participants than controls reported much or very much improvement (45% vs. 13%; p = .03). Satisfaction was high, and 30 of 31 participants attended six sessions or more. CONCLUSION: An online-supported cognitive-behavioral program for people with KOA delivered by occupational therapists is feasible and may contribute to improved physical function.

Serum vaspin concentration in elderly patients with type 2 diabetes mellitus and macrovascular complications.

BACKGROUND: Adipose tissue, an endocrine organ of the body, is involved in some obesity-related disease states such as insulin resistance, diabetes mellitus, and atherosclerosis. Vaspin is a novel adipocyte with insulin sensitizing effects. In this study, we planned to estimate serum vaspin concentrations as related to glycemic status and the presence of macrovascular complications among elderly patients with type-2 diabetes mellitus (T2DM). METHODS: A total of 230 elderly patients with T2DM were evaluated. These patients were divided into two groups: patients without complications (T2DM group, n = 110), and patients with macrovascular complications (T2DM + MC group, n = 120). In addition, 60 healthy elderly subjects were enrolled and assigned into the control group (NC group). Relevant parameters were matched for age and gender ratio. Serum vaspin concentrations were measured by Enzyme-linked immunosorbent assay (ELISA). Anthropometric measurements, plasma glucose and HbA1C levels, insulin concentration, liver and kidney functions, and lipid profile were measured for each participant. RESULTS: Serum vaspin concentrations were significantly higher in the T2DM group than in the T2DM + MC group (F = 13.122, P < 0.01). These concentrations were also significantly higher among females, compared to males (T = 3.567, P < 0.05). Logistic regression analysis revealed that serum vaspin concentration, systolic blood pressure, HDL-C and T2DM duration were independent influencing factors for diabetic macrovascular complications. CONCLUSION: Serum vaspin may be considered as a potential marker to assess the status of elderly patients with T2DM and the risk of developing serious macrovascular complications. Further prospective studies are warranted. TRIAL REGISTRATION: ChiCTR-OPC-14005698 , retrospectively registered on 20 Dec. 2014.

Exercise Prescriptions in Older Adults.

Regular physical activity and exercise are important for healthy aging and are beneficial for chronic disease management. Exercise prescriptions for older adults should account for the individual's health status and functional capacity. Any amount of exercise is better than being sedentary, even if health status prevents a person from achieving recommended goals. For most health outcomes, more benefits occur with physical activity performed at higher intensity, greater frequency, or longer duration. Guidelines recommend at least 150 minutes of moderate-intensity aerobic activity or 75 minutes of vigorous-intensity aerobic activity and at least two days of muscle-strengthening activities per week. Key components of the prescription include setting achievable activity goals, identifying barriers and providing potential solutions, and providing specific recommendations on the type, frequency, and intensity of activities. Older adults will derive distinct benefits from aerobic exercise, strength or resistance training, flexibility or stretching exercises, and balance training. Many community resources are available to help older adults begin a more active lifestyle.

A novel cell adhesion region in tropoelastin mediates attachment to integrin αVß5.

Tropoelastin protein monomers assemble to form elastin. Cellular integrin αVß3 binds RKRK at the C-terminal tail of tropoelastin. We probed cell interactions with tropoelastin by deleting the RKRK sequence to identify other cell-binding interactions within tropoelastin. We found a novel human dermal fibroblast attachment and spreading site on tropoelastin that is located centrally in the molecule. Inhibition studies demonstrated that this cell adhesion was not mediated by either elastin-binding protein or glycosaminoglycans. Cell interactions were divalent cation-dependent, indicating integrin dependence. Function-blocking monoclonal antibodies revealed that αV integrin(s) and integrin αVß5 specifically were critical for cell adhesion to this part of tropoelastin. These data reveal a common αV integrin-binding theme for tropoelastin: αVß3 at the C terminus and αVß5 at the central region of tropoelastin. Each αV region contributes to fibroblast attachment and spreading, but they differ in their effects on cytoskeletal assembly.

Longitudinal functional recovery after geriatric cardiac surgery.

BACKGROUND: Impaired functional and cognitive status is an important outcome for older adults undergoing major cardiac surgery. We conducted this pilot study to gauge feasibility of assessing these outcomes longitudinally, from preoperatively up to two time points postoperatively to assess for recovery. METHODS: We interviewed patients aged ≥ 65 y preoperatively and repeated functional and cognitive assessments at 4-6 wk and 4-6 mo postoperatively. Simple unadjusted linear regression was used to test whether baseline measures changed at each follow-up time point. Then we used a longitudinal model to predict postoperative recovery overall, adjusting for comorbidity. RESULTS: A total of 62 patients (age 74.7 ± 5.9) underwent scheduled cardiac surgery. Preoperative activities of daily living (ADL) impairment was associated with poorer functional recovery at 4-6 wk postoperatively with each baseline ADL impairment conferring recovery of 0.5 fewer ADLs (P < 0.05). By 4-6 mo, we could no longer detect a difference in recovery. Preoperative cognition and physical activity were not associated with postoperative changes in these domains. CONCLUSIONS: A preoperative and postoperative evaluation of function and cognition was integrated into the surgical care of older patients. Preoperative impairments in ADLs may be a means to identify patients who might benefit from careful postoperative planning, especially in terms of assistance with self-care during the first 4-6 wk after cardiac surgery.

Palliative care considerations in frail older adults.

Frailty is a common geriatric syndrome characterized by a decline in physical and cognitive abilities and an increased vulnerability to stressors such as illnesses and injuries. As the global population is aging, the prevalence of frailty is growing. Frail older adults are at substantial risk of developing mobility and self-care difficulties, hospitalization, and death. Frailty is also associated with a high symptom burden and psychosocial stress, including malnutrition, pain, fatigue, weakness, cognitive loss, depression, falls, and sleep disorders, among others. The role of palliative care is gaining attention in medical literature because frailty is associated with increased morbidity and mortality. While there are no specific guidelines yet for when palliative care should be consulted in older patients with frailty, it has been proposed that palliative care should be considered in frail patients with continued functional decline, increased healthcare utilization, and uncontrolled symptoms. Palliative care can aid in communication with patients and families, establishing goals of care and treatment preferences, improving pain and symptom control, addressing psychosocial and spiritual needs, advance care planning, caregiver needs, and end-of-life care. Once frailty is identified, a comprehensive evaluation of the patient's physical, psychosocial, and spiritual aspects of care is essential for establishing a patient-centered treatment plan. This paper aims to guide clinicians in providing patient-centered care for older adults with frailty in the outpatient setting. Through a comprehensive literature review, we describe the leading models of frailty, frailty screening tools used in the clinical setting, and the assessment and management of palliative care needs in frail patients. We also describe emerging models of care focusing on palliative care for older adults with frailty and discuss issues related to access to palliative care for this population.

Does computerized cognitive training improve diabetes self-management and cognition? A randomized control trial of middle-aged and older veterans with type 2 diabetes.

AIMS: This randomized control trial compared an adaptive computerized cognitive training intervention with a non-adaptive version. The primary hypothesis predicted better diabetes self-management in type 2 diabetes patients at 6 months post-intervention than baseline in the adaptive arm, with seven secondary outcomes. METHODS: Intent-to-treat analysis of veterans without dementia aged 55+ from the Bronx, NY and Ann Arbor, MI (N = 90/per arm) used linear mixed model analyses. RESULTS: Contrary to the hypothesis, only memory showed more improvement in the adaptive arm (p < 0.01). Post-hoc analyses combined the two arms; self-management improved at six-months post-intervention (p < 0.001). Memory, executive functions/attention, prospective memory, diastolic blood pressure, and systolic blood pressure improved (p < 0.05); hemoglobin A1c and medication adherence did not improve significantly. CONCLUSIONS: The adaptive computerized cognitive training was not substantially better than non-adaptive, but may improve memory. Post-hoc results for the combined arms suggest computer-related activities may improve diabetes self-management and other outcomes for middle-aged and older patients with type 2 diabetes. Practice effects or awareness of being studied cannot be ruled out.

Framework for virtual education of COVID-19 vaccines for Mandarin-speaking learners: an educational intervention module.

BACKGROUND: In the United States, patients with limited English proficiency face significant barriers to comprehending and acting upon health-related information, particularly during the COVID-19 pandemic. The ability of health professionals to communicate COVID-19-related information to Mandarin-speaking patients has proved critical in discussions about vaccine efficacy, side effects, and post-vaccine protection. METHODS: The authors created a one-hour educational module to help Mandarin-speaking medical students better convey COVID-19 vaccine information to Mandarin-only speakers. The module is composed of an educational guide, which introduced key terminology and addressed commonly asked questions, and pre- and post-surveys. The authors recruited 59 Mandarin-speaking medical students all of whom had previously completed a medical Mandarin elective. The module and surveys were distributed and completed in August 2021. Data analysis measured the change in aggregate mean for subjective five-point Likert-scale questions and change in percent accuracy for objective knowledge-based questions. RESULTS: 86.4% of participants were primary English speakers with variable levels of Mandarin proficiency. The educational module significantly improved participants' subjective comfort level in discussing the COVID-19 vaccine in English and Mandarin. The largest improvement in both English and Mandarin was demonstrated in participants' ability to explain differences between the COVID-19 vaccines, with an aggregate mean improvement of 0.39 for English and 1.48 for Mandarin. Survey respondents also demonstrated increased percent accuracy in knowledge-based objective questions in Mandarin. CONCLUSIONS: This module provides Mandarin-learning medical students with skills to deliver reliable information to the general population and acts as a model for the continued development of educational modules for multilingual medical professionals.

Mechanism of KMT5B haploinsufficiency in neurodevelopment in humans and mice.

Pathogenic variants in KMT5B, a lysine methyltransferase, are associated with global developmental delay, macrocephaly, autism, and congenital anomalies (OMIM# 617788). Given the relatively recent discovery of this disorder, it has not been fully characterized. Deep phenotyping of the largest (n = 43) patient cohort to date identified that hypotonia and congenital heart defects are prominent features that were previously not associated with this syndrome. Both missense variants and putative loss-of-function variants resulted in slow growth in patient-derived cell lines. KMT5B homozygous knockout mice were smaller in size than their wild-type littermates but did not have significantly smaller brains, suggesting relative macrocephaly, also noted as a prominent clinical feature. RNA sequencing of patient lymphoblasts and Kmt5b haploinsufficient mouse brains identified differentially expressed pathways associated with nervous system development and function including axon guidance signaling. Overall, we identified additional pathogenic variants and clinical features in KMT5B-related neurodevelopmental disorder and provide insights into the molecular mechanisms of the disorder using multiple model systems.

Physical Function in Middle-aged and Older Adults With Type 1 Diabetes: Long-term Follow-up of the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications Study.

OBJECTIVE: To describe the prevalence and clinical correlates of functional limitations in middle-aged and older adults with long-standing type 1 diabetes. RESEARCH DESIGN AND METHODS: Functional limitations were assessed for 1,094 participants in the Epidemiology of Diabetes Interventions and Complications (EDIC) study, a multicenter, longitudinal, observational follow-up of participants with type 1 diabetes randomly assigned to intensive or conventional diabetes therapy during the Diabetes Control and Complications Trial (DCCT). The primary outcome measure was a score <10 on the Short Physical Performance Battery (SPPB). The secondary outcome, self-reported functional limitation, was assessed by written questionnaire. Logistic regression models were used to assess associations of both outcomes with demographic and clinical factors (glycemic and nonglycemic factors, micro- and macrovascular complications, DCCT cohort, and treatment assignment). RESULTS: Participants were 53% male, with mean ± SD age 59.5 ± 6.8 years and diabetes duration 37.9 ± 4.9 years. The prevalence of SPPB score <10 was 21%. The prevalence of self-reported functional limitations was 48%. While DCCT treatment assignment was not associated with physical function outcomes measured ∼25 years after the end of the DCCT, the time-weighted mean DCCT/EDIC HbA1c was associated with both outcomes. Other clinical factors associated with both outcomes in multivariable analyses were BMI, general psychological distress, and cardiac autonomic neuropathy. CONCLUSIONS: Almost half of the middle-aged and older adults with long-standing type 1 diabetes reported functional limitations, which were associated with higher HbA1c and BMI, general psychological distress, and cardiac autonomic neuropathy. Future research is needed to determine whether these findings are generalizable.

Cotreatment with BCL-2 antagonist sensitizes cutaneous T-cell lymphoma to lethal action of HDAC7-Nur77-based mechanism.

Pan-histone deacetylase inhibitors, for example, vorinostat and panobinostat (LBH589; Novartis Pharmaceuticals, East Hanover, NJ), have shown clinical efficacy against advanced cutaneous T-cell lymphoma (CTCL). However, the molecular basis of this activity remains unclear. HDAC7, a class IIA histone deacetylase (HDAC), is overexpressed in thymocytes, where it represses expression of the proapoptotic nuclear orphan receptor Nur77. Here, we demonstrate that treatment with panobinostat rapidly inhibits the in vitro and intracellular activity, as well as the mRNA and protein levels of HDAC7, and induces expression and translocation of Nur77 to the mitochondria. There, Nur77 converts death resistance protein Bcl-2 into a killer protein, promoting cell death of cultured and patient-derived human CTCL cells. Treatment with panobinostat improved survival of athymic nude mice implanted with human CTCL cells. Ectopic expression of Nur77 induced apoptosis and sensitized HH cells to panobinostat, whereas combined knockdown of Nur77 and its family member Nor1 was necessary to inhibit panobinostat-induced apoptosis of CTCL cells. Cotreatment with the Bcl-2/Bcl-x(L) antagonist ABT-737 decreased resistance and synergistically induced apoptosis of human CTCL cells. These findings mechanistically implicate HDAC7 and Nur77 in sensitizing human CTCL cells to panobinostat as well as suggest that cotreatment with an anti-Bcl-2 agent would augment the anti-CTCL activity of panobinostat.

Geriatric conditions develop in middle-aged adults with diabetes.

BACKGROUND: Geriatric conditions, collections of symptoms common in older adults and not necessarily associated with a specific disease, increase in prevalence with advancing age. These conditions are important contributors to the complex health status of older adults. Diabetes mellitus is known to co-occur with geriatric conditions in older adults and has been implicated in the pathogenesis of some conditions. OBJECTIVE: To investigate the prevalence and incidence of geriatric conditions in middle-aged and older-aged adults with diabetes. DESIGN: Secondary analysis of nationally-representative, longitudinal health interview survey data (Health and Retirement Study waves 2004 and 2006). PARTICIPANTS: Respondents 51 years and older in 2004 (n=18,908). MAIN MEASURES: Diabetes mellitus. Eight geriatric conditions: cognitive impairment, falls, incontinence, low body mass index, dizziness, vision impairment, hearing impairment, pain. KEY RESULTS: Adults with diabetes, compared to those without, had increased prevalence and increased incidence of geriatric conditions across the age spectrum (p< 0.01 for each age group from 51-54 years old to 75-79 years old). Differences between adults with and without diabetes were most marked in middle-age. Diabetes was associated with the two-year cumulative incidence of acquiring new geriatric conditions (odds ratio, 95% confidence interval: 1.8, 1.6-2.0). A diabetes-age interaction was discovered: as age increased, the association of diabetes with new geriatric conditions decreased. CONCLUSIONS: Middle-aged, as well as older-aged, adults with diabetes are at increased risk for the development of geriatric conditions, which contribute substantially to their morbidity and functional impairment. Our findings suggest that adults with diabetes should be monitored for the development of these conditions beginning at a younger age than previously thought.

Domains 12 to 16 of tropoelastin promote cell attachment and spreading through interactions with glycosaminoglycan and integrins alphaV and alpha5beta1.

Elastin is an extracellular matrix component with key structural and biological roles in elastic tissues. Interactions between resident cells and tropoelastin, the monomer of elastin, underpin elastin's regulation of cellular processes. However, the nature of tropoelastin-cell interactions and the contributions of individual tropoelastin domains to these interactions are only partly elucidated. In this study, we identified and characterized novel cell-adhesive sites in the tropoelastin N-terminal region between domains 12 and 16. We found that this region interacts with αV and α5ß1 integrin receptors, which mediate cell attachment and spreading. A peptide sequence from within this region, spanning domains 14 to mid-domain 16, binds heparan sulfate through electrostatic interactions with peptide lysine residues and induces conformational ordering of the peptide. We propose that domains 14-16 direct initial cell attachment through cell-surface heparan sulfate glycosaminoglycans, followed by αV and α5ß1 integrin-promoted attachment and spreading on domains 12-16 of tropoelastin. These findings advance our mechanistic understanding of elastin matrix biology, with the potential to enhance tissue regenerative outcomes of elastin-based materials.

HDAC6 inhibition enhances 17-AAG--mediated abrogation of hsp90 chaperone function in human leukemia cells.

Histone deacetylase 6 (HDAC6) is a heat shock protein 90 (hsp90) deacetylase. Treatment with pan-HDAC inhibitors or depletion of HDAC6 by siRNA induces hyperacetylation and inhibits ATP binding and chaperone function of hsp90. Treatment with 17-allylamino-demothoxy geldanamycin (17-AAG) also inhibits ATP binding and chaperone function of hsp90, resulting in polyubiquitylation and proteasomal degradation of hsp90 client proteins. In this study, we determined the effect of hsp90 hyperacetylation on the anti-hsp90 and antileukemia activity of 17-AAG. Hyperacetylation of hsp90 increased its binding to 17-AAG, as well as enhanced 17-AAG-mediated attenuation of ATP and the cochaperone p23 binding to hsp90. Notably, treatment with 17-AAG alone also reduced HDAC6 binding to hsp90 and induced hyperacetylation of hsp90. This promoted the proteasomal degradation of HDAC6. Cotreatment with 17-AAG and siRNA to HDAC6 induced more inhibition of hsp90 chaperone function and depletion of BCR-ABL and c-Raf than treatment with either agent alone. In addition, cotreatment with 17-AAG and tubacin augmented the loss of survival of K562 cells and viability of primary acute myeloid leukemia (AML) and chronic myeloid leukemia (CML) samples. These findings demonstrate that HDAC6 is an hsp90 client protein and hyperacetylation of hsp90 augments the anti-hsp90 and antileukemia effects of 17-AAG.