Central role of Prominin-1 in lipid rafts during liver regeneration

The Impact of Glycosylation on the Functional Activity of CD133 and the Accuracy of Its Immunodetection

The membrane glycoprotein CD133 (prominin-1) is widely regarded as the main molecular marker of cancer stem cells, which are the most malignant cell subpopulation within the tumor, responsible for tumor growth and metastasis. For this reason, CD133 is considered a promising prognostic biomarker and molecular target for antitumor therapy. Under normal conditions, CD133 is present on the cell membrane in glycosylated form. However, in malignancies, altered glycosylation apparently leads to changes in the functional activity of CD133 and the availability of some of its epitopes for antibodies. This review focuses on CD133's glycosylation in human cells and its impact on the function of this glycoprotein. The association of CD133 with proliferation, differentiation, apoptosis, autophagy, epithelial-mesenchymal transition, the organization of plasma membrane protrusions and extracellular trafficking is discussed. In this review, particular attention is paid to the influence of CD133's glycosylation on its immunodetection. A list of commercially available and custom antibodies with their characteristics is provided. The available data indicate that the development of CD133-based biomedical technologies should include an assessment of CD133's glycosylation in each tumor type.

Emerging roles of prominin-1 (CD133) in the dynamics of plasma membrane architecture and cell signaling pathways in health and disease

Prominin-1 (CD133) is a cholesterol-binding membrane glycoprotein selectively associated with highly curved and prominent membrane structures. It is widely recognized as an antigenic marker of stem cells and cancer stem cells and is frequently used to isolate them from biological and clinical samples. Recent progress in understanding various aspects of CD133 biology in different cell types has revealed the involvement of CD133 in the architecture and dynamics of plasma membrane protrusions, such as microvilli and cilia, including the release of extracellular vesicles, as well as in various signaling pathways, which may be regulated in part by posttranslational modifications of CD133 and its interactions with a variety of proteins and lipids. Hence, CD133 appears to be a master regulator of cell signaling as its engagement in PI3K/Akt, Src-FAK, Wnt/β-catenin, TGF-β/Smad and MAPK/ERK pathways may explain its broad action in many cellular processes, including cell proliferation, differentiation, and migration or intercellular communication. Here, we summarize early studies on CD133, as they are essential to grasp its novel features, and describe recent evidence demonstrating that this unique molecule is involved in membrane dynamics and molecular signaling that affects various facets of tissue homeostasis and cancer development. We hope this review will provide an informative resource for future efforts to elucidate the details of CD133's molecular function in health and disease.

Identification of a cryptic functional apolipophorin-III domain within the Prominin-1 gene of Litopenaeus vannamei

The Apolipophorin-III (apoLp-III) is reported as an essential protein element in lipids transport and incorporation in lepidopterans. Structurally, apoLp-III has an α-helix bundle structure composed of five α-helices. Interestingly, classic studies proposed a structural switch triggered by its interaction with lipids, where the α-helix bundle opens. Currently, the study of the apoLp-III has been limited to insects, with no homologs identified in other arthropods. By implementing a structure-based search with the Phyre2 algorithm surveying the shrimp Litopenaeus vannamei's transcriptome, we identified a putative apoLp-III in this farmed penaeid (LvApoLp-III). Unlike canonical apoLp-III, the LvApoLp-III was identified as an internal domain within the transmembrane protein Prominin-1. Structural modeling using the template-based Phyre2 and template-free AlphaFold algorithms rendered two distinct structural topologies: the α-helix bundle and a coiled-coil structure. Notably, the secondary structure composition on both models was alike, with differences in the orientation and distribution of the α-helices and hydrophobic moieties. Both models provide insights into the classical structural switch induced by lipids in apoLp-III. To corroborate structure/function inferences, we cloned the synthetic LvApoLp-III domain, overexpressed, and purified the recombinant protein. Circular dichroism measurements with the recombinant LvApoLp-III agreed with the structural models. In vitro liposome interaction demonstrated that the apoLp-III domain within the PROM1 of L.vannamei associated similarly to exchangeable apolipoproteins. Altogether, this work reports the presence of an apolipophorin-III domain in crustaceans for the first time and opens questions regarding its function and importance in lipid metabolism or the immune system.

Signaling pathways of liver regeneration: Biological mechanisms and implications

The liver possesses a unique regenerative ability to restore its original mass, in this regard, partial hepatectomy (PHx) and partial liver transplantation (PLTx) can be executed smoothly and safely, which has important implications for the treatment of liver disease. Liver regeneration (LR) can be the very complicated procedure that involves multiple cytokines and transcription factors that interact with each other to activate different signaling pathways. Activation of these pathways can drive the LR process, which can be divided into three stages, namely, the initiation, progression, and termination stages. Therefore, it is important to investigate the pathways involved in LR to elucidate the mechanism of LR. This study reviews the latest research on the key signaling pathways in the different stages of LR.

PROM1-mediated cell signal transduction in cancer stem cells and hepatocytes

Prominin-1 (PROM1), also called CD133, is a penta-span transmembrane protein that is localized in membrane protrusions, such as microvilli and filopodia. It is known to be expressed in cancer stem cells and various progenitor cells of bone marrow, liver, kidney, and intestine. Accumulating evidence has revealed that PROM1 has multiple functions in various organs, such as eye, tooth, peripheral nerve, and liver, associating with various molecular protein partners. PROM1 regulates PKA-induced gluconeogenesis, TGFβ-induced fibrosis, and IL-6-induced regeneration in the liver, associating with Radixin, SMAD7, and GP130, respectively. In addition, PROM1 is necessary to maintain cancer stem cell properties by activating PI3K and β-Catenin. PROM1-deficienct mice also show distinct phenotypes in eyes, brain, peripheral nerves, and tooth. Here, we discuss recent findings of PROM1-mediated signal transduction. [BMB Reports 2023; 56(2): 65-70].