PU.1 is linking the glycolytic enzyme HK3 in neutrophil differentiation and survival of APL cells

The transcription factor PU.1 is a master regulator of myeloid differentiation and function. On the other hand, only scarce information is available on PU.1-regulated genes involved in cell survival. We now identified the glycolytic enzyme hexokinase 3 (HK3), a gene with cytoprotective functions, as transcriptional target of PU.1. Interestingly, HK3 expression is highly associated with the myeloid lineage and was significantly decreased in acute myeloid leukemia patients compared with normal granulocytes. Moreover, HK3 expression was significantly lower in acute promyelocytic leukemia (APL) compared with non-APL patient samples. In line with the observations in primary APL patient samples, we observed significantly higher HK3 expression during neutrophil differentiation of APL cell lines. Moreover, knocking down PU.1 impaired HK3 induction during neutrophil differentiation. In vivo binding of PU.1 and PML-RARA to the HK3 promoter was found, and PML-RARA attenuated PU.1 activation of the HK3 promoter. Next, inhibiting HK3 in APL cell lines resulted in significantly reduced neutrophil differentiation and viability compared with control cells. Our findings strongly suggest that HK3 is: (1) directly activated by PU.1, (2) repressed by PML-RARA, and (3) functionally involved in neutrophil differentiation and cell viability of APL cells.

ATRA resolves the differentiation block in t(15;17) acute myeloid leukemia by restoring PU.1 expression

Tightly regulated expression of the transcription factor PU.1 is crucial for normal hematopoiesis. PU.1 knockdown mice develop acute myeloid leukemia (AML), and PU.1 mutations have been observed in some populations of patients with AML. Here we found that conditional expression of promyelocytic leukemia-retinoic acid receptor alpha (PML-RARA), the protein encoded by the t(15;17) translocation found in acute promyelocytic leukemia (APL), suppressed PU.1 expression, while treatment of APL cell lines and primary cells with all-trans retinoic acid (ATRA) restored PU.1 expression and induced neutrophil differentiation. ATRA-induced activation was mediated by a region in the PU.1 promoter to which CEBPB and OCT-1 binding were induced. Finally, conditional expression of PU.1 in human APL cells was sufficient to trigger neutrophil differentiation, whereas reduction of PU.1 by small interfering RNA (siRNA) blocked ATRA-induced neutrophil differentiation. This is the first report to show that PU.1 is suppressed in acute promyelocytic leukemia, and that ATRA restores PU.1 expression in cells harboring t(15;17).

Trastornos de autoagresión hacia las uñas. Autoagressive nail disoreders

Background and objective: Autoaggressive nail disorders span a wide range of clinical changes, but they often remain undiagnosed. This article is intended to help the practitioner to make the correct diagnosis and institute an accepted treatment. Material and method: The patient charts of 1800 patients seen by the author between the years 2000-2011 in 6 different European countries were evaluated using photographs of finger and toenails. Results: The most common condition is onycholysis induced by overzealous manicure. The habit tic of maniacally pushing back the proximal nail fold of one or both thumb nails is frequent and often misdiagnosed. Heller’s median canaliform dystrophy is probably also due to a similar injury mechanism. Onychophagia is relatively com- mon and seen both in children and adults. Onychotillomania is less frequent and almost exclusively seen in adults. Onychotemnomania is even less frequent. Onychoteiromania is sowhere between the latter two habits. Onychodaknomania is exceptional and usually a sign of an underlying psychiatric disorder. There was no substantial difference in the prevalence of these conditions among the different countries visited. Conclusions: Auto aggressive nail injury is common, but often difficult to diagnose. Patient care requires not only an in-depth knowledge of virtually all nail diseases, but also a cautious and empathic patient examination and treatment