Saturated fatty acid alters embryonic cortical neurogenesis through modulation of gene expression in neural stem cells
JOURNAL OF NUTRITIONAL BIOCHEMISTRY
Authors: Ardah, Mustafa T.; Parween, Shama; Varghese, Divya S.; Emerald, Bright Starling; Ansari, Suraiya A.
Abstract
A perturbed maternal metabolic environment such as chronically elevated circulating free fatty acids have been shown to affect stem cell fate during embryonic neurogenesis. However, molecular mechanisms behind this are not well defined, especially in human. Here in using directed differentiation of human embryonic stem cells (hESCs) into cortical neurons as model, we show that chronically elevated saturated fatty acid (palmitate) results in decreased proliferation of neural stem cells and increased differentiation into neurons. This phenotype could be due to palmitate mediated increased expression of key genes needed for neuronal differentiation such as EOMES, TBRI, NEURODI and RELN and reduced expression of SREBP regulated lipogenic genes at early stages of cortical differentiation. Furthermore, palmitate treatment increased histone acetylation globally and at select gene promoters among affected genes. We also found differential expression of several lncRNAs associated with cellular stress and metabolic diseases in the presence of palmitate including BDNF-AS suggesting the contribution of additional epigenetic regulatory mechanisms. Together, our results show that saturated fatty acid affects developmental neurogenesis through modulation of gene expression and through epigenetic regulatory mechanisms. (C) 2018 Elsevier Inc. All rights reserved.
Endogenous antigen presentation impacts on T-box transcription factor expression and functional maturation of CD8(+) T cells
BLOOD
Authors: Smith, Corey; Elhassen, Diah; Gras, Stephanie; Wynn, Katherine K.; Dasari, Vijayendra; Tellam, Judy; Tey, Siok-Keen; Rehan, Sweera; Liu, Yu Chih; Rossjohn, Jamie; Burrows, Scott R.; Khanna, Rajiv
Abstract
T-box transcription factors T-bet (Tbx21) and Eomesodermin (Eomes) are critical players in CD8(+) cytotoxic T lymphocyte effector function and differentiation, but how the expression of these transcription factors is regulated remains poorly defined. Here we show that dominant T cells directed toward human CMV, expressing significantly higher levels of T-bet with graded loss of Eomes expression (T-bet(hi)Eomes(hi/lo)), are more efficient in recognizing endogenously processed peptide-major histocompatibility complexes (pMHC) compared with subdominant virus-specific T cells expressing lower levels of T-bet and high levels of Eomes (T-bet(int)Eomes(hi)). Paradoxically, the T-bet(hi)Eomes(hi/lo) dominant populations that efficiently recognized endogenous antigen demonstrated lower intrinsic avidity for pMHC, whereas T-bet(int) Eomes(hi) subdominant populations were characterized by higher pMHC avidity and less efficient recognition of virus-infected cells. Importantly, differential endogenous viral antigen recognition by CMV-specific CD8(+) T cells also correlated with the differentiation status and expression of perforin, granzyme B and K. Furthermore, we demonstrate that the expression of T-bet correlates with clonal expansion, differentiation status, and expression of perforin, granzyme B and K in antigen-specific T cells. These findings illustrate how endogenous viral antigen presentation during persistent viral infection may influence the transcriptional program of virus-specific T cells and their functional profile in the peripheral blood of humans. (Blood. 2012;120(16):3237-3245)