Muler, I. | bioRxiv Science

bioRxiv2020

An instructive role for IL7RA in the development of human B-cell precursor leukemia.

B-cell precursor acute lymphoblastic leukemia (BCP-ALL) is preceded by a clinically silent pre-leukemia. Experimental models that authentically re-capitulate disease initiation and progression in human cells are lacking. We previously described activating mutations in interleukin 7 receptor alpha (IL7RA) that are associated with the poor-prognosis Philadelphia-like (Ph-like) subtype of BCP-ALL. Whether IL7RA signaling has a role in initiation of human BCP-ALL is unknown. IL7RA is essential for mouse B-cell development; however, patients with truncating IL7RA germline mutations develop normal mature B-cell populations. Herein, we explore the consequences of aberrant IL7RA signaling activation in human hematopoietic progenitors on malignant B-cell development. Transplantation of human cord-blood hematopoietic progenitors transduced with activated mutant IL7RA into NOD/LtSz-scid IL2R{gamma}null mice resulted in B-cell differentiation arrest with aberrant expression of CD34+ and persistence of pro-B cells that survive despite failing to achieve productive rearrangement of immunoglobulin V(D)J gene segments. Activation of IL7RA signaling enhanced self-renewal and facilitated the development of a BCP-ALL in secondary transplanted mice. The development of leukemia was associated with spontaneous acquired deletions in CDKN2A/B and IKZF1 similar to what is observed in Ph-like BCP-ALL in humans. Single cell gene expression analysis suggested that pre-leukemic cells resided within a subpopulation of early B-cell precursors with CD34+CD10highCD19low immunophenotype. The development of a bona fide BCP-ALL from IL7RA transduced cells supports the hypothesis that aberrant activation of the IL7RA pathway in human B-cell lineage progenitors has an instructive role by creating a pre-leukemic state which is vulnerable to transformation. These are the first demonstrations of a role for IL7RA in human B-cell differentiation and of a de-novo Ph-like BCP-ALL development from normal human hematopoietic progenitors in vivo.

cancer biology↗

bioRxiv2019

Comprehensive post mortem brain samples analysis detects global reduction of multiple proteasome subunits expression in schizophrenia

OBJECTIVEA main challenge in the study of schizophrenia is its high heterogeneity. While it is generally accepted that there exist several biological mechanisms that may define distinct schizophrenia subtypes, they havent been identified yet. We applied comprehensive gene expression analysis, searching for molecular signals that differentiate patients with schizophrenia from healthy controls, and examined whether the identified signal characterizes a particular subgroup of the patients. METHODSWe performed transcriptome sequencing of 14 superior temporal gyrus (STG) samples of relatively young (mean age: 44) subjects with schizophrenia and 15 matched controls from the Stanley Medical Research Institute. Analyses of differential expression and pathway enrichment were applied and the results were compared with those obtained from an independent cohort of elderly (mean age: 74) patients. Replicability was then tested on six additional independent datasets of various brain regions. RESULTSThe two STG cohorts of relatively young and elderly subjects showed high replicability. Pathway enrichment analysis of the down-regulated genes pointed to proteasome-related pathways. Meta-analysis of differential expression identified down-regulation of 12 of 39 proteasome subunits in schizophrenia. Down-regulation of multiple proteasome subunits was replicated in six additional datasets (overall 8 cohorts, with 267 schizophrenia and 266 control samples, from 5 brain regions, were studied). This signal was concentrated in a subgroup of the patients. CONCLUSIONSWe detect global down-regulation of proteasome subunits in a subgroup of the patients with schizophrenia. The proteasome is a major intracellular protein degradation system, where ubiquitinated proteins (proteins bound by the small protein called ubiquitin) are targeted for degradation. We hypothesize that the down-regulation we detect leads to proteasome dysfunction that causes accumulation of ubiquitinated proteins. Such accumulation has recently been identified, also in a subgroup of the studied patients with schizophrenia. Thus, down-regulation of proteasome subunits might define a biological subtype of schizophrenia.

neuroscience↗