Anti-PEX19 monoclonal antibody, clone HU644

Peroxisomes constitute special cellular organelles which display a variety of metabolic functions including fatty acid oxidation and free radical elimination. Abundance of these flexible organelles varies in response to different environmental stimuli. It has been demonstrated that PEX11 beta, a peroxisomal membrane elongation factor, is involved in the regulation of size, shape and number of peroxisomes. To investigate the role of Pex11 beta in neural differentiation of mouse embryonic stem cells (mESCs), we generated a stably transduced mESCs line that derives the expression of a short hairpin RNA against Pex11 beta gene following doxycycline (Dox) induction. Knock-down of Pex11 beta, during neural differentiation, significantly reduced the expression of neural progenitor cells and mature neuronal markers (p<0.05) indicating that decreased expression of Pex11 beta suppresses neuronal maturation. Additionally, mRNA levels of other peroxisome-related genes such as PMP70, Pex11 alpha, Catalase, Pex19 and Pex5 were also significantly reduced by Pex11 beta knock-down (p<0.05). Interestingly, pretreatment of transduced mESCs with peroxisome proliferator-activated receptor c agonist (pioglitazone (Pio)) ameliorated the inhibitory effects of Pex11 beta knock down on neural differentiation. Pio also significantly (p<0.05) increased the expression of neural progenitor and mature neuronal markers besides the expression of peroxisomal genes in transduced mESC. Results elucidated the importance of Pex11 beta expression in neural differentiation of mESCs, thereby highlighting the essential role of peroxisomes in mammalian neural differentiation. The observation that Pio recovered peroxisomal function and improved neural differentiation of Pex11 beta knocked-down mESCs, proposes a potential new pharmacological implication of Pio for neurogenesis in patients with peroxisomal defects. (C) 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

Yarrowia lipolytica Pex23p and Saccharomyces cerevisiae Pex30p, Pex31p, and Pex32p comprise a family of dysferlin domain-containing peroxins. We show that the deletion of their Pichia pastoris homologues, PEX30 and PEX31, does not affect the function or division of methanol-induced peroxisomes but results in fewer and enlarged, functional, oleate-induced peroxisomes. Synthesis of Pex30p is constitutive, whereas that of Pex31p is oleate-induced but at a much lower level relative to Pex30p. Pex30p interacts with Pex31p and is required for its stability. At steady state, both Pex30p and Pex31p exhibit a dual localization to the endoplasmic reticulum (ER) and peroxisomes. However, Pex30p is localized mostly to the ER, whereas Pex31p is predominantly on peroxisomes. Consistent with ER-to-peroxisome trafficking of these proteins, Pex30p accumulates on peroxisomes upon overexpression of Pex31p. Additionally, Pex31p colocalizes with Pex30p at the ER in pex19 Delta cells and can be chased from the ER to peroxisomes in a Pex19p-dependent manner. The dysferlin domains of Pex30p and Pex31p, which are dispensable for their interaction, stability, and subcellular localization, are essential for normal peroxisome number and size. The growth environment-specific role of these peroxins, their dual localization, and the function of their dysferlin domains provide novel insights into peroxisome morphogenesis.