Hepatocyte nuclear factor 4α multiple isoforms, their functions, and their interactomes.

Hepatocyte nuclear factor 4-alpha (HNF4α) is a master regulator gene belonging to the nuclear receptor superfamily and is involved in regulating a wide range of critical biological processes in different organs. Structurally, the HNF4A locus is organized into two independent promoters and is subjected to alternative splicing to produce twelve distinct isoforms. However, little is known about the biological impact of each isoform and the mechanisms by which they regulate transcription. Proteomic analyses have led to the identification of proteins that interact with specific HNF4α isoforms. The identification and validation of these interactions and their roles in the co-regulation of targeted gene expression are essential to better understand the role of this transcription factor in different biological processes and pathologies. This review addresses the discoveries of different HNF4α isoforms and the main functions of the P1 and P2 isoform subgroups. It also provides information on the most recent focus areas in research on the nature and function of proteins associated with each of the isoforms in some biological contexts.

Human Hepatocyte Nuclear Factor 4-α Encodes Isoforms with Distinct Transcriptional Functions.

HNF4α is a nuclear receptor produced as 12 isoforms from two promoters by alternative splicing. To characterize the transcriptional capacities of all 12 HNF4α isoforms, stable lines expressing each isoform were generated. The entire transcriptome associated with each isoform was analyzed as well as their respective interacting proteome. Major differences were noted in the transcriptional function of these isoforms. The α1 and α2 isoforms were the strongest regulators of gene expression whereas the α3 isoform exhibited significantly reduced activity. The α4, α5, and α6 isoforms, which use an alternative first exon, were characterized for the first time, and showed a greatly reduced transcriptional potential with an inability to recognize the consensus response element of HNF4α. Several transcription factors and coregulators were identified as potential specific partners for certain HNF4α isoforms. An analysis integrating the vast amount of omics data enabled the identification of transcriptional regulatory mechanisms specific to certain HNF4α isoforms, hence demonstrating the importance of considering all isoforms given their seemingly diverse functions.

P1 promoter-driven HNF4α isoforms are specifically repressed by ß-catenin signaling in colorectal cancer cells.

HNF4α is a key nuclear receptor for regulating gene expression in the gut. Although both P1 and P2 isoform classes of HNF4α are expressed in colonic epithelium, specific inhibition of P1 isoforms is commonly found in colorectal cancer. Previous studies have suggested that P1 and P2 isoforms might regulate different cellular functions. Despite these advances, it remains unclear whether these isoform classes are functionally divergent in the context of human biology. Here, the consequences of specific inhibition of P1 or P2 isoform expression was measured in a human colorectal cancer cell transcriptome. Results indicate that P1 isoforms were specifically associated with the control of cell metabolism, whereas P2 isoforms globally supported aberrant oncogenic signalization, promoting cancer cell survival and progression. P1 promoter-driven isoform expression was found to be repressed by ß-catenin, one of the earliest oncogenic pathways to be activated during colon tumorigenesis. These findings identify a novel cascade by which the expression of P1 isoforms is rapidly shut down in the early stages of colon tumorigenesis, allowing a change in HNF4α-dependent transcriptome, thereby promoting colorectal cancer progression.This article has an associated First Person interview with the first author of the paper.

Transcription factor CUX1 is required for intestinal epithelial wound healing and targets the VAV2-RAC1 Signalling complex.

Intestinal epithelial cells form a protective barrier in limiting gut luminal content potentially harmful to the host. Upon gut epithelium injury, several signals instruct epithelial cells to undergo a rapid healing process. Defects in this process induce inflammatory responses and can further evolve into chronic gut inflammatory diseases. We previously identified the transcription factor CUX1 as crucial for protecting against experimental colitis in mice. However, the precise molecular mechanisms by which CUX1 intervenes during this biological process are unknown. Our aim was to evaluate CUX1 biological and functional roles during intestinal epithelial cell wound healing. RNAi knockdown of CUX1 in intestinal epithelial cells revealed a crucial role for this regulator in migratory response following wounding assays. Gene expression profiling identified several gene transcripts modulated in absence of CUX1 during wound healing for which a significant number was associated with cell motility and cytoskeleton function. Chromatin immunoprecipitation assays identified the guanine nucleotide exchange factor Vav2 gene as a direct target for CUX1. Coincidently, reduction of VAV2 in absence of CUX1 was associated with a significant decrease of RAC1 activity in response to epithelial wounding. Our results identify a novel pathway by which CUX1 regulates normal intestinal epithelial cell restitution.

The G protein-coupled P2Y6 receptor promotes colorectal cancer tumorigenesis by inhibiting apoptosis.

Colorectal tumors are immersed in an array of tumor-promoting factors including extracellular nucleotides such as uridine 5'­diphosphate (UDP). UDP is the endogenous agonist of the G protein-coupled P2Y6 receptor (P2Y6R), which may contribute to the formation of a tumor-promoting microenvironment by coordinating resistance to apoptosis. Colorectal cancer (CRC) was chemically induced in P2ry6 knockout (P2ry6-/-) mice using azoxymethane and dextran sulfate sodium challenges. Mice were euthanatized and their tumor load determined. Fixed tissues were stained for histological and immunohistochemistry analysis. Tumoroids were also prepared from CRC tumors resected from P2ry6+/+ mice to determine the role of P2Y6R in resistance to apoptosis, whereas HT29 carcinoma cells were used to elucidate the signaling mechanism involved in P2Y6R anti-apoptotic effect. P2ry6-/- mice developed a reduced number of colorectal tumors with apparent tumors having smaller volumes. Overall dysplastic score was significantly lower in P2ry6-/- animals. Stimulation of P2Y6R with the selective agonist MRS2693 protected HT-29 cells from TNFα-induced apoptosis. This protective effect was mediated by the stabilizing phosphorylation of the X-linked inhibitor of apoptosis protein (XIAP) by AKT. Using CRC-derived tumoroids, P2Y6R activation was found to contribute to chemoresistance since addition of the P2Y6R agonist MRS2693 significantly prevented the cytotoxic effect of 5-fluorouracil. The present study shows that sustained activation of P2Y6R may contribute to intestinal tumorigenesis by blocking the apoptotic process and by contributing to chemoresistance, a substantial concern in the treatment of patients with CRC. These results suggest that P2Y6R may represent a prime target for reducing colorectal carcinogenesis.

Epithelial Src homology region 2 domain-containing phosphatase-1 restrains intestinal growth, secretory cell differentiation, and tumorigenesis.

Shp-1 (Src homology region 2 domain-containing protein tyrosine phosphatase-1) is a phosphatase that is highly expressed in hematopoietic and epithelial cells. Whereas its function is largely characterized in hematopoietic cells, its role in epithelial cells, such as intestinal epithelial cells (IECs), is not well known. Here, we generated mice with an IEC-specific knockout of Shp-1 (Src homology region 2 domain-containing phosphatase-1; Shp-1IEC-KO). We showed that the loss of epithelial Shp-1 leads to an intestinalomegaly that is associated with an increase in epithelial cell proliferation and size. Histologic analysis demonstrates significant perturbation of the crypt-villus architecture with an apparent increase in the number of goblet and Paneth cells and increased expression of their respective markers {Muc2 (mucin 2), αDef, and Sox9 [SRY (sex determining region Y)-box 9]}. Expansion of intermediate cells-common progenitors of goblet and Paneth cell lineages-is also observed in Shp-1IEC-KO mice. Although sustained activation of Wnt/ß-catenin and PI3K/Akt/mammalian target of rapamycin signaling is observed, Shp-1IEC-KO mice fail to develop any intestinal tumors after 15 mo; however, the loss of Shp-1 in IECs markedly enhances tumor load ApcMin/+ mice. These findings show a novel role for Shp-1 in the regulation of IEC growth and secretory lineage allocation, possibly via modulation of PI3K/Akt-dependent signaling pathways. Finally, Shp-1 does not function as a classic tumor suppressor gene in the intestinal epithelium.-Leblanc, C., Langlois, M.-J., Coulombe, G., Vaillancourt-Lavigueur, V., Jones, C., Carrier, J. C., Boudreau, F., Rivard, N. Epithelial Src homology region 2 domain-containing phosphatase-1 restrains intestinal growth, secretory cell differentiation, and tumorigenesis.

Phenotypic Analysis of Organoids by Proteomics.

The development of 3D cell cultures into self-organizing organ-like structures named organoids provides a model that better reflects in vivo organ physiology and their functional properties. Organoids have been established from several organs, such as the intestine, prostate, brain, liver, kidney and pancreas. With recent advances in high-throughput and -omics profiling technologies, it is now possible to study the mechanisms of cellular organisation at the systems level. It is therefore not surprising that these methods are now used to characterize organoids at the transcriptomic, proteomic, chromatin state and transcription factor DNA-binding levels. These approaches can therefore provide a wealth of information regarding both the mechanisms involved in different diseases, and those involved in cell responses to different conditions, in a more in vivo setting. The authors provide an overview of the potential applications of quantitative mass spectrometry with organoid culture, and how the use of large-scale proteome measurements is emerging in different organoid systems.

Subcellular proteomics analysis of different stages of colorectal cancer cell lines.

Studying cell differentiation and transformation allows a better understanding of the mechanisms involved in the initiation and the evolution of cancer. The role of proteins which participate in these processes is dependent on their location within the cell. Determining the subcellular localization of proteins or the changes in localization is, therefore, paramount in elucidating their role. Using quantitative mass spectrometry, we characterized the protein expression and subcellular localization of nearly 5000 proteins from seven different colorectal cancer (CRC) cell lines, as well as normal colon fibroblasts and intestinal epithelial cells. This cellular characterization allowed the identification of colon cancer-associated proteins with differential expression patterns as well as deregulated protein networks and pathways. Indeed, our results demonstrate differential expression of proteins involved in cell adhesion, cytoskeleton, and transcription in colon cancer cells compared to normal colon-derived cells. Pathway analyses identified different cellular functions, including endocytosis and eIF2 signaling, whose deregulation correlates with mutations found in the different CRC phenotypes. Our results provide an unbiased, quantitative and high-throughput approach to measure changes in protein expression and subcellular protein locations in different CRC cell lines.

Identification of GATA-4 as a novel transcriptional regulatory component of regenerating islet-derived family members.

Intestinal epithelial cells are exposed to luminal bacterial threat and require adequate defense mechanisms to ensure host protection and epithelium regeneration against possible deleterious damage. Differentiated intestinal epithelial cells produce antimicrobial and regenerative components that protect against such challenges. Few intestinal specific transcription factors have been identified to control the switching from repression to activation of this class of gene. Herein, we show that gene transcription of some regenerating islet-derived (REG) family members is dependent on the transcription factor GATA-4. Silencing of GATA-4 expression in cultured intestinal epithelial cells identified Reg3ß as a target gene using an unbiased approach of gene expression profiling. Co-transfection and RNA interference assays identified complex GATA-4-interactive transcriptional components required for the activation or repression of Reg3ß gene activity. Conditional deletion of Gata4 in the mouse intestinal epithelium supported its regulatory role for Reg1, Reg3α, Reg3ß and Reg3γ genes. Reg1 dramatic down-modulation of expression in Gata4 conditional null mice was associated with a significant decrease in intestinal epithelial cell migration. Altogether, these results identify a novel and complex role for GATA-4 in the regulation of REG family members gene expression.

Distinct Roles for Intestinal Epithelial Cell-Specific Hdac1 and Hdac2 in the Regulation of Murine Intestinal Homeostasis.

The intestinal epithelium responds to and transmits signals from the microbiota and the mucosal immune system to insure intestinal homeostasis. These interactions are in part conveyed by epigenetic modifications, which respond to environmental changes. Protein acetylation is an epigenetic signal regulated by histone deacetylases, including Hdac1 and Hdac2. We have previously shown that villin-Cre-inducible intestinal epithelial cell (IEC)-specific Hdac1 and Hdac2 deletions disturb intestinal homeostasis. To determine the role of Hdac1 and Hdac2 in the regulation of IEC function and the establishment of the dual knockout phenotype, we have generated villin-Cre murine models expressing one Hdac1 allele without Hdac2, or one Hdac2 allele without Hdac1. We have also investigated the effect of short-term deletion of both genes in naphtoflavone-inducible Ah-Cre and tamoxifen-inducible villin-Cre(ER) mice. Mice with one Hdac1 allele displayed normal tissue architecture, but increased sensitivity to DSS-induced colitis. In contrast, mice with one Hdac2 allele displayed intestinal architecture defects, increased proliferation, decreased goblet cell numbers as opposed to Paneth cells, increased immune cell infiltration associated with fibrosis, and increased sensitivity to DSS-induced colitis. In comparison to dual knockout mice, intermediary activation of Notch, mTOR, and Stat3 signaling pathways was observed. While villin-Cre(ER) Hdac1 and Hdac2 deletions led to an impaired epithelium and differentiation defects, Ah-Cre-mediated deletion resulted in blunted proliferation associated with the induction of a DNA damage response. Our results suggest that IEC determination and intestinal homeostasis are highly dependent on Hdac1 and Hdac2 activity levels, and that changes in the IEC acetylome may alter the mucosal environment.

SHP-2 Phosphatase Prevents Colonic Inflammation by Controlling Secretory Cell Differentiation and Maintaining Host-Microbiota Homeostasis.

Polymorphisms in the PTPN11 gene encoding for the tyrosine phosphatase SHP-2 were described in patients with ulcerative colitis. We have recently demonstrated that mice with an intestinal epithelial cell-specific deletion of SHP-2 (SHP-2(IEC-KO) ) develop severe colitis 1 month after birth. However, the mechanisms by which SHP-2 deletion induces colonic inflammation remain to be elucidated. We generated SHP-2(IEC-KO) mice lacking Myd88 exclusively in the intestinal epithelium. The colonic phenotype was histologically analyzed and cell differentiation was determined by electron microscopy and lysozyme or Alcian blue staining. Microbiota composition was analyzed by 16S sequencing. Results show that innate defense genes including those specific to Paneth cells were strongly up-regulated in SHP-2-deficient colons. Expansion of intermediate cells (common progenitors of the Goblet and Paneth cell lineages) was found in the colon of SHP-2(IEC-KO) mice whereas Goblet cell number was clearly diminished. These alterations in Goblet/intermediate cell ratio were noticed 2 weeks after birth, before the onset of inflammation and were associated with significant alterations in microbiota composition. Indeed, an increase in Enterobacteriaceae and a decrease in Firmicutes were observed in the colon of these mice, indicating that dysbiosis also occurred prior to inflammation. Importantly, loss of epithelial Myd88 expression inhibited colitis development in SHP-2(IEC-KO) mice, rescued Goblet/intermediate cell ratio, and prevented NFκB hyperactivation and inflammation. These data indicate that SHP-2 is functionally important for the maintenance of appropriate barrier function and host-microbiota homeostasis in the large intestine. J. Cell. Physiol. 231: 2529-2540, 2016. © 2016 The Authors. Journal of Cellular Physiology published by Wiley Periodicals, Inc.

Bmp signaling in colonic mesenchyme regulates stromal microenvironment and protects from polyposis initiation.

In the colon, myofibroblasts are primary contributors in the establishment of the microenvironment involved in tissue homeostasis. Alterations in myofibroblast functions lead to changes resulting in a toxic microenvironment nurturing tumorigenesis. Bone morphogenetic proteins (Bmps) are morphogens known to play key roles in adult gut homeostasis. Studies in genetically-modified mice have shown that Bmp disruption in all cell layers leads to the development of gut polyposis. In contrast, our studies showed that loss of Bmp exclusively in the gastrointestinal epithelium resulted in increased epithelial proliferation without polyposis initiation, thus suggesting a key role for mesenchymal Bmp signaling in polyposis initiation. In order to identify the role of mesenchymal Bmp signaling on the microenvironment and its impact on colonic mucosa, a mouse model was generated with suppression of Bmp signaling exclusively in myofibroblasts (Bmpr1aΔMES). Bmpr1aΔMES mice exhibited increased subepithelial proliferation with changes in cellular composition leading to the development of a primed stroma with modulation of extracellular matrix proteins, immune cells and cytokines as early as 90 days of age. This microenvironmental deregulation was associated with increased polyposis initiation at one year of age. These results are the first to demonstrate that mesenchymal Bmpr1a inactivation alone is sufficient to prompt an expansion of myofibroblasts leading to the development of a reactive mesenchyme that contributes to polyposis initiation in the colon. These findings support the novel concept that inhibition of Bmp signaling in mesenchymal cells surrounding the normal epithelium leads to important changes instructing a toxic microenvironment sufficient to induce colonic polyposis.

Cathepsin B promotes colorectal tumorigenesis, cell invasion, and metastasis.

Cathepsin B is a cysteine proteinase that primarily functions as an endopeptidase within endolysosomal compartments in normal cells. However, during tumoral expansion, the regulation of cathepsin B can be altered at multiple levels, thereby resulting in its overexpression and export outside of the cell. This may suggest a possible role of cathepsin B in alterations leading to cancer progression. The aim of this study was to determine the contribution of intracellular and extracellular cathepsin B in growth, tumorigenesis, and invasion of colorectal cancer (CRC) cells. Results show that mRNA and activated levels of cathepsin B were both increased in human adenomas and in CRCs of all stages. Treatment of CRC cells with the highly selective and non-permeant cathepsin B inhibitor Ca074 revealed that extracellular cathepsin B actively contributed to the invasiveness of human CRC cells while not essential for their growth in soft agar. Cathepsin B silencing by RNAi in human CRC cells inhibited their growth in soft agar, as well as their invasion capacity, tumoral expansion, and metastatic spread in immunodeficient mice. Higher levels of the cell cycle inhibitor p27(Kip1) were observed in cathepsin B-deficient tumors as well as an increase in cyclin B1. Finally, cathepsin B colocalized with p27(Kip1) within the lysosomes and efficiently degraded the inhibitor. In conclusion, the present data demonstrate that cathepsin B is a significant factor in colorectal tumor development, invasion, and metastatic spreading and may, therefore, represent a potential pharmacological target for colorectal tumor therapy.

Contribution of Sp1 to Telomerase Expression and Activity in Skin Keratinocytes Cultured With a Feeder Layer.

The growth of primary keratinocytes is improved by culturing them with a feeder layer. The aim of this study was to assess whether the feeder layer increases the lifespan of cultured epithelial cells by maintaining or improving telomerase activity and expression. The addition of an irradiated fibroblast feeder layer of either human or mouse origin (i3T3) helped maintain telomerase activity as well as expression of the transcription factor Sp1 in cultured keratinocytes. In contrast, senescence occurred earlier, together with a reduction of Sp1 expression and telomerase activity, in keratinocytes cultured without a feeder layer. Telomerase activity was consistently higher in keratinocytes grown on the three different feeder layers tested relative to cells grown without them. Suppression of Sp1 expression by RNA inhibition (RNAi) reduced both telomerase expression and activity in keratinocytes and also abolished their long-term growth capacity suggesting that Sp1 is a key regulator of both telomerase gene expression and cell cycle progression of primary cultured human skin keratinocytes. The results of the present study therefore suggest that the beneficial influence of the feeder layer relies on its ability to preserve telomerase activity in cultured human keratinocytes through the maintenance of stable levels of Sp1 expression.

Evaluation of a Web-based tailored intervention (TAVIE en santé) to support people living with HIV in the adoption of health promoting behaviours: an online randomized controlled trial protocol.

BACKGROUND: Long-term use of antiretroviral therapy, normal aging, and presence of certain risk factors are associated with metabolic disorders that predispose persons living with HIV to diabetes and cardiovascular diseases. The emergence and progression of these disorders can be prevented by adopting healthy behaviours. Based on the theory of planned behaviour, the Web-based tailored intervention TAVIE en santé was developed. The aim of this study is to evaluate the effectiveness of TAVIE en santé in order to support people living with HIV in the adoption of health promoting behaviours. METHODS/DESIGN: An online randomized controlled trial with parallel-groups will be conducted across Canada. To participate in this study, people living with HIV must be: ≥ 18 years, able to read/understand French or English, have access to the Internet. A convenience sample of 750 participants will be randomly assigned either to an experimental group (TAVIE en santé, n = 375) or to a control group (websites, n = 375) (1:1 allocation ratio). The TAVIE en santé intervention is composed of seven interactive computer sessions, lasting between 5 and 10 min. The sessions, hosted by a virtual nurse, aim to develop and strengthen skills required for behaviour change. The control group will receive a validated list of five predetermined conventional health-related Websites. The adoption of health behaviour (smoking cessation or physical activity or healthy eating) is the principal outcome. Cognitions (intention, attitude, perceived behavioral control) are the secondary outcomes. Health indicators will also be assessed. All outcomes will be measured with a self-administered online questionnaire and collected three times: at baseline, 3 and 6 months after. The principal analyses will focus on differences between the two trial groups using Intention-to-Treat analysis. DISCUSSION: This study will yield new results about the efficacy of Web-based tailored health behaviours change interventions in the context of chronic disease. The TAVIE en santé intervention could constitute an accessible complementary service in support of existing specialized services to support people living with HIV adopt health behaviors. TRIAL REGISTRATION: NCT02378766 , assigned on March 3th 2015.

Rationale, design and baseline characteristics of a randomized controlled trial of a web-based computer-tailored physical activity intervention for adults from Quebec City.

BACKGROUND: The relationship between physical activity and cardiovascular disease (CVD) protection is well documented. Numerous factors (e.g. patient motivation, lack of facilities, physician time constraints) can contribute to poor PA adherence. Web-based computer-tailored interventions offer an innovative way to provide tailored feedback and to empower adults to engage in regular moderate- to vigorous-intensity PA. To describe the rationale, design and content of a web-based computer-tailored PA intervention for Canadian adults enrolled in a randomized controlled trial (RCT). METHODS/DESIGN: 244 men and women aged between 35 and 70 years, without CVD or physical disability, not participating in regular moderate- to vigorous-intensity PA, and familiar with and having access to a computer at home, were recruited from the Quebec City Prospective Urban and Rural Epidemiological (PURE) study centre. Participants were randomized into two study arms: 1) an experimental group receiving the intervention and 2) a waiting list control group. The fully automated web-based computer-tailored PA intervention consists of seven 10- to 15-min sessions over an 8-week period. The theoretical underpinning of the intervention is based on the I-Change Model. The aim of the intervention was to reach a total of 150 min per week of moderate- to vigorous-intensity aerobic PA. DISCUSSION: This study will provide useful information before engaging in a large RCT to assess the long-term participation and maintenance of PA, the potential impact of regular PA on CVD risk factors and the cost-effectiveness of a web-based computer-tailored intervention. TRIAL REGISTRATION: ISRCTN36353353 registered on 24/07/2014.

The acetylome regulators Hdac1 and Hdac2 differently modulate intestinal epithelial cell dependent homeostatic responses in experimental colitis.

Histone deacetylases (Hdac) remove acetyl groups from proteins, influencing global and specific gene expression. Hdacs control inflammation, as shown by Hdac inhibitor-dependent protection from dextran sulfate sodium (DSS)-induced murine colitis. Although tissue-specific Hdac knockouts show redundant and specific functions, little is known of their intestinal epithelial cell (IEC) role. We have shown previously that dual Hdac1/Hdac2 IEC-specific loss disrupts cell proliferation and determination, with decreased secretory cell numbers and altered barrier function. We thus investigated how compound Hdac1/Hdac2 or Hdac2 IEC-specific deficiency alters the inflammatory response. Floxed Hdac1 and Hdac2 and villin-Cre mice were interbred. Compound Hdac1/Hdac2 IEC-deficient mice showed chronic basal inflammation, with increased basal disease activity index (DAI) and deregulated Reg gene colonic expression. DSS-treated dual Hdac1/Hdac2 IEC-deficient mice displayed increased DAI, histological score, intestinal permeability, and inflammatory gene expression. In contrast to double knockouts, Hdac2 IEC-specific loss did not affect IEC determination and growth, nor result in chronic inflammation. However, Hdac2 disruption protected against DSS colitis, as shown by decreased DAI, intestinal permeability and caspase-3 cleavage. Hdac2 IEC-specific deficient mice displayed increased expression of IEC gene subsets, such as colonic antimicrobial Reg3b and Reg3g mRNAs, and decreased expression of immune cell function-related genes. Our data show that Hdac1 and Hdac2 are essential IEC homeostasis regulators. IEC-specific Hdac1 and Hdac2 may act as epigenetic sensors and transmitters of environmental cues and regulate IEC-mediated mucosal homeostatic and inflammatory responses. Different levels of IEC Hdac activity may lead to positive or negative outcomes on intestinal homeostasis during inflammation.

Participation in regular leisure-time physical activity among individuals with type 2 diabetes not meeting Canadian guidelines: the influence of intention, perceived behavioral control, and moral norm.

BACKGROUND: Most people with type 2 diabetes do not engage in regular leisure-time physical activity. The theory of planned behavior and moral norm construct can enhance our understanding of physical activity intention and behavior among this population. PURPOSE: This study aims to identify the determinants of both intention and behavior to participate in regular leisure-time physical activity among individuals with type 2 diabetes who not meet Canada's physical activity guidelines. METHOD: By using secondary data analysis of a randomized computer-tailored print-based intervention, participants (n = 200) from the province of Quebec (Canada) completed and returned a baseline questionnaire measuring their attitude, perceived behavioral control, and moral norm. One month later, they self-reported their level of leisure-time physical activity. RESULTS: A hierarchical regression equation showed that attitude (beta = 0.10, P < 0.05), perceived behavioral control (beta = 0.37, P < 0.001), and moral norm (beta = 0.45, P < 0.001) were significant determinants of intention, with the final model explaining 63% of the variance. In terms of behavioral prediction, intention (beta = 0.34, P < 0.001) and perceived behavioral control (beta = 0.16, P < 0.05) added 17% to the variance, after controlling the effects of the experimental condition (R (2) = 0.04, P < 0.05) and past participation in leisure-time physical activity (R (2) = 0.22, P < 0.001). The final model explained 43% of the behavioral variance. Finally, the bootstrapping procedure indicated that the influence of moral norm on behavior was mediated by intention and perceived behavioral control. CONCLUSION: The determinants investigated offered an excellent starting point for designing appropriate counseling messages to promote leisure-time physical activity among individuals with type 2 diabetes.

Psychosocial determinants of healthy sleep habits in adults with type 1 and type 2 diabetes.

Background: Many adults with type 1 (T1D) and type 2 diabetes (T2D) have inadequate sleep increasing their risk of hyperglycemia and developing complications. The objective was to identify psychosocial determinants of healthy sleep habits (HSH) among adults with T1D and T2D. Methods: The two HSH were: avoiding screen use in bed and having sleep regularity. Adults (≥18 years) with T1D and T2D were invited to complete an anonymous online survey. The questionnaires were based on the Reasoned Action Approach and formative qualitative research previously conducted in 56 adults with T1D and T2D. Habit was included as an additional variable for screen use in bed. Results: In total, 320 adults with diabetes (T1D: 39%; T2D: 61%) completed the questionnaires (screen use in bed: 174; sleep timing: 146). Close to 75% of participants reported screen use in bed and close to 90% reported sleep timing variability in the last month. Perceived behavioral control (PBC) to avoid screen use in bed (ß = -0.4486, p < 0.0001), habit of using screens in bed (ß = 0.4002; p < 0.0001), and age (ß = -0.0202; p = 0.0086) were determinants of screen use in bed, and this model explained 71% of the variance. PBC for sleep regularity (ß = -0.2909; p = 0.0004) and being female (ß = 0.5057; p = 0.0069) were determinants of sleep timing variability, and this model explained 28% of the variance. The most important beliefs associated with each HSH were identified to obtain information to design targeted interventions. Conclusions: Few adults with diabetes have HSH. Screen use in bed was strongly influenced by habit and the results suggest that both HSH are not easy to adopt among adults with diabetes. Younger adults with diabetes should be prioritized for screen use in bed, while females with diabetes should be prioritized for sleep timing variability. Adults with diabetes should have access to behavior change interventions to encourage them to adopt HSH.

ASCL2 is a key regulator of the proliferation-differentiation equilibrium in the esophageal epithelium.

The esophagus is protected from the hostile environment by a stratified epithelium, which renews rapidly. Homeostasis of this epithelium is ensured by a rare population of stem cells in the basal layer: Keratin 15+ (Krt15+) cells. However, little is known about the molecular mechanisms regulating their distinct features, namely self-renewal, potency and epithelial regeneration. Achaete-scute family BHLH transcription factor 2 (ASCL2) is strongly upregulated in Krt15+ stem cells and is known to contribute to stem cell maintenance in other tissues. Herein, we investigated the role of ASCL2 in maintaining homeostasis under normal and stress conditions in the esophageal epithelium. ASCL2 overexpression severely dysregulated cell differentiation and cell fate. Proliferation was also reduced due potentially to a blockage in the G1 phase of the cell cycle or an induction of quiescence. Mass spectrometry analysis confirmed alterations in several proteins associated with differentiation and the cell cycle. In addition, overexpression of ASCL2 enhanced resistance to radiation and chemotherapeutic drugs. Overall, these results denote the role of ASCL2 as a key regulator of the proliferation-differentiation equilibrium in the esophageal epithelium.