The RNA-binding proteins LIN28A and LIN28B have diverse functions in embryonic stem cells, cellular reprogramming, growth, and oncogenesis. Many of these effects occur via direct inhibition of Let-7 microRNAs (miRNAs), although Let-7-independent effects have been surmised. We report that intestine targeted expression of LIN28B causes intestinal hypertrophy, crypt expansion, and Paneth cell loss. Furthermore, LIN28B fosters intestinal polyp and adenocarcinoma formation. To examine potential Let-7-independent functions of LIN28B, we pursued ribonucleoprotein cross-linking, immunoprecipitation, and high-throughput sequencing (CLIP-seq) to identify direct RNA targets. This revealed that LIN28B bound a substantial number of mRNAs and modestly augmented protein levels of these target mRNAs in vivo. Conversely, Let-7 had a profound effect; modulation of Let-7 levels via deletion of the mirLet7c2/mirLet7b genes recapitulated effects of Lin28b overexpression. Furthermore, intestine-specific Let-7 expression could reverse hypertrophy and Paneth cell depletion caused by Lin28b. This was independent of effects on insulin-PI3K-mTOR signaling. Our study reveals that Let-7 miRNAs are critical for repressing intestinal tissue growth and promoting Paneth cell differentiation. Let-7-dependent effects of LIN28B may supersede Let-7-independent effects on intestinal tissue growth. In summary, LIN28B can definitively act as an oncogene in the absence of canonical genetic alterations.

Cardiac amyloidosis is an under-recognized and potentially fatal cause of heart failure and other cardiovascular manifestations. It is caused by deposition of misfolded precursor proteins as fibrillary amyloid deposits in cardiac tissues. The two primary subtypes of systemic amyloidosis causing cardiac involvement are immunoglobulin light chain (AL), a plasma cell dyscrasia, and transthyretin (ATTR), itself subdivided into a hereditary subtype caused by a gene mutation of the ATTR protein, and an age-related wild type, which occurs in the absence of a gene mutation. Clinical recognition requires a high index of suspicion, inclusive of the extracardiac manifestations of both subtypes. Diagnostic workup includes screening for serum and/or R ESUM E L'amylose cardiaque est une cause sous-reconnue et potentiellement mortelle d'insuffisance cardiaque et d'autres manifestations cardiovasculaires. Elle est caus ee par le d epôt, dans les tissus cardiaques, de prot eines pr ecurseurs mal repli ees prenant la forme de fibrilles amyloïdes. On distingue deux grands sous-types d'amylose syst emique entraînant une atteinte cardiaque : l'amylose à chaînes l egères d'immunoglobulines (AL), une forme de dyscrasie plasmocytaire; et l'amylose à transthyr etine (ATTR), dont il existe un sous-type h er editaire, caus e par une mutation du gène codant pour la TTR, et un sous-type à TTR sauvage, li e au vieillissement et se produisant en l'absence de mutation g enique. La reconnaissance clinique n ecessite

Pancreatic exocrine cell plasticity can be observed during development, pancreatitis with subsequent regeneration, and also transformation. For example, acinar-ductal metaplasia (ADM) occurs during acute pancreatitis and might be viewed as a prelude to pancreatic intraepithelial neoplasia (PanIN) and pancreatic ductal adenocarcinoma (PDAC) development. To elucidate regulatory processes that overlap ductal development, ADM, and the progression of normal cells to PanIN lesions, we undertook a systematic approach to identify the Prrx1 paired homeodomain Prrx1 transcriptional factor as a highly regulated gene in these processes. Prrx1 annotates a subset of pancreatic ductal epithelial cells in Prrx1creER T2 -IRES-GFP mice. Furthermore, sorted Prrx1 + cells have the capacity to self-renew and expand during chronic pancreatitis. The two isoforms, Prrx1a and Prrx1b, regulate migration and invasion, respectively, in pancreatic cancer cells. In addition, Prrx1b is enriched in circulating pancreatic cells (Pdx1cre;LSL-Kras G12D/+ ;p53 fl/+ ;R26YFP). Intriguingly, the Prrx1b isoform, which is also induced in ADM, binds the Sox9 promoter and positively regulates Sox9 expression. This suggests a new hierarchical scheme whereby a Prrx1-Sox9 axis may influence the emergence of acinar-ductal metaplasia and regeneration. Furthermore, our data provide a possible explanation of why pancreatic cancer is skewed toward a ductal fate.

IMPORTANCE Childhood abuse significantly increases the risk of developing posttraumatic stress disorder (PTSD), often accompanied by symptoms of borderline personality disorder (BPD) and other co-occurring mental disorders. Despite the high prevalence, systematic evaluations of evidence-based treatments for PTSD after childhood abuse are sparse.OBJECTIVE To compare the efficacy of dialectical behavior therapy for PTSD (DBT-PTSD), a new, specifically designed, phase-based treatment program, against that of cognitive processing therapy (CPT), one of the best empirically supported treatments for PTSD.