Immigrant family skills-building to prevent tobacco use in Latino youth: study protocol for a community-based participatory randomized controlled trial.

BACKGROUND: Despite declines over recent years, youth tobacco and other substance use rates remain high. Latino youth are at equal or increased risk for lifetime tobacco, alcohol, marijuana, and other illicit drug use compared with their white peers. Family plays an important and influential role in the lives of youth, and longitudinal research suggests that improving parenting skills may reduce youth substance use. However, few interventions are oriented towards immigrant Latino families, and none have been developed and evaluated using a community-based participatory research (CBPR) process that may increase the effectiveness and sustainability of such projects. Therefore, using CBPR principles, we developed a randomized clinical trial to assess the efficacy of a family-skills training intervention to prevent tobacco and other substance use intentions in Latino youth. METHODS/DESIGN: In collaboration with seven Latino community-serving agencies, we will recruit and randomize 336 immigrant families, into intervention or delayed treatment conditions. The primary outcome is youth intention to smoke 6 months post intervention. The intervention consists of eight parent and four youth sessions targeting parenting skills and parent-youth relational factors associated with lower smoking and other substance use in youth. DISCUSSION: We present the study protocol for a family intervention using a CBPR randomized clinical trial to prevent smoking among Latino youth. The results of this trial will contribute to the limited information on effective and sustainable primary prevention programs for tobacco and other substance use directed at the growing US Latino communities. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01442753.

A novel domain mediates insulin-induced proteasomal degradation of insulin receptor substrate 1 (IRS-1).

Insulin receptor substrate-1 (IRS-1) plays a pivotal role in insulin signaling, therefore its degradation is exquisitely regulated. Here, we show that insulin-stimulated degradation of IRS-1 requires the presence of a highly conserved Ser/Thr-rich domain that we named domain involved in degradation of IRS-1 (DIDI). DIDI (amino acids 386-430 of IRS-1) was identified by comparing the intracellular degradation rate of several truncated forms of IRS-1 transfected into CHO cells. The isolated DIDI domain underwent insulin-stimulated Ser/Thr phosphorylation, suggesting that it serves as a target for IRS-1 kinases. The effects of deletion of DIDI were studied in Fao rat hepatoma and in CHO cells expressing Myc-IRS-1(WT) or Myc-IRS-1(Δ386-430). Deletion of DIDI maintained the ability of IRS-1(Δ386-434) to undergo ubiquitination while rendering it insensitive to insulin-induced proteasomal degradation, which affected IRS-1(WT) (80% at 8 h). Consequently, IRS-1(Δ386-434) mediated insulin signaling (activation of Akt and glycogen synthesis) better than IRS-1(WT). IRS-1(Δ386-434) exhibited a significant greater preference for nuclear localization, compared with IRS-1(WT). Higher nuclear localization was also observed when cells expressing IRS-1(WT) were incubated with the proteasome inhibitor MG-132. The sequence of DIDI is conserved more than 93% across species, from fish to mammals, as opposed to approximately 40% homology of the entire IRS-1. These findings implicate DIDI as a novel, highly conserved domain of IRS-1, which mediates its cellular localization, rate of degradation, and biological activity, with a direct impact on insulin signal transduction.