Biogenesis of peroxisomes: isolation and characterization of two distinct peroxisomal populations from normal and regenerating rat liver.

Abstract

Abstract. According to Poole et al. (1970. J. Cell Biol. 45:408-415), newly synthesized peroxisomal proteins are incorporated uniformly into peroxisomes (PO) of different size classes, suggesting that rat hepatic PO form a homogeneous population. There is however increasing cytochemical and biochemical evidence that PO in rat liver are heterogenous, undergoing significant modulations in shape and size in process of PO morphogenesis (Yamamoto and Fahimi, 1987. J. Cell Biol. 105:713-722). In the present study, the kinetics of incorporation of newly synthesized proteins into distinct PO-subpopulations have been studied using short-term in vivo labeling (5-90 min). Two distinct "heavy" and "light" crude PO fractions were prepared by differential pelleting from normal and regenerating liver, and highly purified PO were subsequently isolated by density-dependent metrizamide gradient centrifugation according to V61kl and Fahimi (1985. Eur. J. Biochem. 149:25%265). The peroxisomal fractions banded at 1.20 and 1.24 g x cm -3. They differed in their mean diameters and form-factors and particularly in respect to the activity of/3-oxidation enzymes which was higher in the "light" PO. Whereas the "light" PO exhibited a single immunoreactive band with the antibody to the 70-kD peroxisomal membrane protein the "heavy" PO contained an additional (68 kD) band. In pulse-labeling experiments "light" PO showed clearly a higher initial rate of incorporation than the "heavy" PO. The relative specific activity in the "heavy" PO fraction, however increased progressively reaching that of "light" PO by 90 min. These observations provide evidence for the existence of different PO populations in rat liver which differ in their morphological and biochemical properties as well as in their rates of incorporation of new proteins.

Endotoxin induces structure-function alterations of rat liver peroxisomes: Kupffer cells released factors as possible modulators

“…Peroxisomes of different densities have been described in normal 52 and regenerating rat liver. 53 Furthermore, peroxisomes are induced by conditions such as hypolipidemic drugs treatment, 50 cold shock, 54 and ischemia and reperfusion. 55 Under these conditions, an additional catalase peak is present in the lighter part of the gradient.…”

“…55 Under these conditions, an additional catalase peak is present in the lighter part of the gradient. Therefore, lighter peroxisomes may represent peroxisomes in the process of maturation, 50,53 or peroxisomal particles generated due to fragmentation of peroxisomal reticulum. 52 The additional peak of peroxisomes in LPS-treated liver represents peroxisomes undergoing autophagy by lysosomes.…”

Peroxisome elongation and constriction but not fission can occur independently of dynamin-like protein 1

“…MBGV-GP, encoding the glycoprotein GP of the Marburg virus, as well as MBGV-GP-specific polyclonal antibodies were kindly provided by Dr S. Becker (University of Marburg, Germany) (Becker et al, 1996). Rabbit polyclonal anti-PMP70 (peroxisomal membrane protein 70) antibodies (Luers et al, 1993) were a gift from Dr A. Völkl (University of Heidelberg, Germany). The rabbit polyclonal anti-DLP1 antibody was described previously (Yoon et al, 1998).…”

Peroxisome Subpopulations of the Rat Liver: Isolation by Immune Free Flow Electrophoresis

“…However, it is quite difficult to purify a definite PO subpopulation by conventional gradient centrifugation because of the very similar sedimentation properties among the subsets and to other subcellular organelles, particularly microsomes. Therefore, even in the subfractionation of rat liver, only POs banding at a density of ‫32.1ف‬ g/cm 3 are obtained in highly purified form (Lüers et al 1993), whereas additional fractions to be collected appear less pure.…”

“…The heterogeneity of peroxisomes (POs) is a wellknown phenomenon that is substantiated or at least supported by several lines of evidence: (a) the demonstration of distinct types of the organelle exhibiting differences in size, shape, and protein composition even in the same tissue (Angermüller and Fahimi 1988;Schrader et al 1994); (b) the isolation of subpopulations by density gradient centrifugation that diverge in their buoyant densities (Aikawa et al 1991;Klucis et al 1991;Lüers et al 1993;Wilcke et al 1995); and (c) the identification of so-called peroxisomal "ghosts" instead of intact POs in severe peroxisomal disorders such as the Zellweger syndrome (Santos et al 1988). Despite the accumulation of such data, a detailed characterization of appropriately divergent subsets of POs has yet to be performed.…”