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Lyons PJ. Inactive metallopeptidase homologs: the secret lives of pseudopeptidases. Front Mol Biosci 2024; 11:1436917. [PMID: 39050735 PMCID: PMC11266112 DOI: 10.3389/fmolb.2024.1436917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2024] [Accepted: 06/25/2024] [Indexed: 07/27/2024] Open
Abstract
Inactive enzyme homologs, or pseudoenzymes, are proteins, found within most enzyme families, that are incapable of performing catalysis. Rather than catalysis, they are involved in protein-protein interactions, sometimes regulating the activity of their active enzyme cousins, or scaffolding protein complexes. Pseudoenzymes found within metallopeptidase families likewise perform these functions. Pseudoenzymes within the M14 carboxypeptidase family interact with collagens within the extracellular space, while pseudopeptidase members of the M12 "a disintegrin and metalloprotease" (ADAM) family either discard their pseudopeptidase domains as unnecessary for their roles in sperm maturation or utilize surface loops to enable assembly of key complexes at neuronal synapses. Other metallopeptidase families contain pseudopeptidases involved in protein synthesis at the ribosome and protein import into organelles, sometimes using their pseudo-active sites for these interactions. Although the functions of these pseudopeptidases have been challenging to study, ongoing work is teasing out the secret lives of these proteins.
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Affiliation(s)
- Peter J. Lyons
- Department of Biology, Andrews University, Berrien Springs, MI, United States
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2
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Jääskeläinen I, Petäistö T, Mirzarazi Dahagi E, Mahmoodi M, Pihlajaniemi T, Kaartinen MT, Heljasvaara R. Collagens Regulating Adipose Tissue Formation and Functions. Biomedicines 2023; 11:biomedicines11051412. [PMID: 37239083 DOI: 10.3390/biomedicines11051412] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 04/28/2023] [Accepted: 05/03/2023] [Indexed: 05/28/2023] Open
Abstract
The globally increasing prevalence of obesity is associated with the development of metabolic diseases such as type 2 diabetes, dyslipidemia, and fatty liver. Excess adipose tissue (AT) often leads to its malfunction and to a systemic metabolic dysfunction because, in addition to storing lipids, AT is an active endocrine system. Adipocytes are embedded in a unique extracellular matrix (ECM), which provides structural support to the cells as well as participating in the regulation of their functions, such as proliferation and differentiation. Adipocytes have a thin pericellular layer of a specialized ECM, referred to as the basement membrane (BM), which is an important functional unit that lies between cells and tissue stroma. Collagens form a major group of proteins in the ECM, and some of them, especially the BM-associated collagens, support AT functions and participate in the regulation of adipocyte differentiation. In pathological conditions such as obesity, AT often proceeds to fibrosis, characterized by the accumulation of large collagen bundles, which disturbs the natural functions of the AT. In this review, we summarize the current knowledge on the vertebrate collagens that are important for AT development and function and include basic information on some other important ECM components, principally fibronectin, of the AT. We also briefly discuss the function of AT collagens in certain metabolic diseases in which they have been shown to play central roles.
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Affiliation(s)
- Iida Jääskeläinen
- ECM-Hypoxia Research Unit, Faculty of Biochemistry and Molecular Medicine, University of Oulu, 90014 Oulu, Finland
| | - Tiina Petäistö
- ECM-Hypoxia Research Unit, Faculty of Biochemistry and Molecular Medicine, University of Oulu, 90014 Oulu, Finland
| | - Elahe Mirzarazi Dahagi
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Montréal, QC H3A 0C7, Canada
| | - Mahdokht Mahmoodi
- Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montréal, QC H3A 0C7, Canada
| | - Taina Pihlajaniemi
- ECM-Hypoxia Research Unit, Faculty of Biochemistry and Molecular Medicine, University of Oulu, 90014 Oulu, Finland
| | - Mari T Kaartinen
- Department of Anatomy and Cell Biology, Faculty of Medicine and Health Sciences, McGill University, Montréal, QC H3A 0C7, Canada
- Faculty of Dental Medicine and Oral Health Sciences, McGill University, Montréal, QC H3A 0C7, Canada
- Division of Experimental Medicine, Faculty of Medicine and Health Sciences, McGill University, Montréal, QC H3A 0C7, Canada
| | - Ritva Heljasvaara
- ECM-Hypoxia Research Unit, Faculty of Biochemistry and Molecular Medicine, University of Oulu, 90014 Oulu, Finland
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Jager M, Lee MJ, Li C, Farmer SR, Fried SK, Layne MD. Aortic carboxypeptidase-like protein enhances adipose tissue stromal progenitor differentiation into myofibroblasts and is upregulated in fibrotic white adipose tissue. PLoS One 2018; 13:e0197777. [PMID: 29799877 PMCID: PMC5969754 DOI: 10.1371/journal.pone.0197777] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Accepted: 05/08/2018] [Indexed: 02/06/2023] Open
Abstract
White adipose tissue expands through both adipocyte hypertrophy and hyperplasia and it is hypothesized that fibrosis or excess accumulation of extracellular matrix within adipose tissue may limit tissue expansion contributing to metabolic dysfunction. The pathways that control adipose tissue remodeling are only partially understood, however it is likely that adipose tissue stromal and perivascular progenitors participate in fibrotic remodeling and also serve as adipocyte progenitors. The goal of this study was to investigate the role of the secreted extracellular matrix protein aortic carboxypeptidase-like protein (ACLP) on adipose progenitor differentiation in the context of adipose tissue fibrosis. Treatment of 10T1/2 mouse cells with recombinant ACLP suppressed adipogenesis and enhanced myofibroblast differentiation, which was dependent on transforming growth factor-β receptor kinase activity. Mice fed a chronic high fat diet exhibited white adipose tissue fibrosis with elevated ACLP expression and cellular fractionation of these depots revealed that ACLP was co-expressed with collagens primarily in the inflammatory cell depleted stromal-vascular fraction (SVF). SVF cells isolated from mice fed a high fat diet secreted increased amounts of ACLP compared to low fat diet control SVF. These cells also exhibited reduced adipogenic differentiation capacity in vitro. Importantly, differentiation studies in primary human adipose stromal cells revealed that mature adipocytes do not express ACLP and exogenous ACLP administration blunted their differentiation potential while upregulating myofibroblastic markers. Collectively, these studies identify ACLP as a stromal derived mediator of adipose progenitor differentiation that may limit adipocyte expansion during white adipose tissue fibrosis.
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Affiliation(s)
- Mike Jager
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Mi-Jeong Lee
- Section of Endocrinology, Diabetes, and Nutrition, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Chendi Li
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Stephen R. Farmer
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Susan K. Fried
- Section of Endocrinology, Diabetes, and Nutrition, Department of Medicine, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Matthew D. Layne
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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Xu Q, Liu W, Liu X, Otkur W, Hayashi T, Yamato M, Fujisaki H, Hattori S, Tashiro SI, Ikejima T. Type I collagen promotes primary cilia growth through down-regulating HDAC6-mediated autophagy in confluent mouse embryo fibroblast 3T3-L1 cells. J Biosci Bioeng 2017; 125:8-14. [PMID: 28811097 DOI: 10.1016/j.jbiosc.2017.07.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2017] [Revised: 07/13/2017] [Accepted: 07/17/2017] [Indexed: 01/06/2023]
Abstract
Primary cilia are microtubule-based organelles that extend from nearly all vertebrate cells. Abnormal ciliogenesis and cilia length are suggested to be associated with hypertension and obesity as well as diseases such as Meckel-Gruber syndrome. Extracellular matrix (ECM), comprising cellular microenvironment, influences cell shape and proliferation. However, influence of ECM on cilia biogenesis has not been well studied. In this study we examined the effects of type I collagen (col I), the major component of ECM, on primary cilia growth. When cultured on collagen-coated dishes, confluent 3T3-L1 cells were found to exhibit fibroblast-like morphology, which was different from the cobblestone-like shape on non-coated dishes. The level of autophagy in the cells cultured on col I-coated dishes was attenuated compared with the cells cultured on non-coated dishes. The cilia of the cells cultured on col I-coated dishes became longer, accompanying increased expression of essential proteins for cilia assembly. Transfection of the siRNA targeting microtubule-associated protein light chain 3 (LC3) further enhanced the length of primary cilia, suggesting that col I positively regulated cilia growth through inhibition of autophagy. Histone deacetylase 6 (HDAC6), which was suggested as a mediator of autophagy in our previous study on primary cilia, was down-regulated with col I. 3T3-L1 cells treated with the siRNA against HDAC6 reduced the autophagy level and enhanced collagen-induced cilia elongation, implying that HDAC6 was involved in mediating autophagy. In conclusion, col I promotes cilia growth through repressing the HDAC-autophagy pathway that can be involved in the interaction between primary cilia and col I.
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Affiliation(s)
- Qian Xu
- China-Japan Research Institute of Medical and Pharmaceutical Sciences, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Weiwei Liu
- China-Japan Research Institute of Medical and Pharmaceutical Sciences, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Xiaoling Liu
- China-Japan Research Institute of Medical and Pharmaceutical Sciences, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Wuxiyar Otkur
- China-Japan Research Institute of Medical and Pharmaceutical Sciences, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Toshihiko Hayashi
- China-Japan Research Institute of Medical and Pharmaceutical Sciences, Shenyang Pharmaceutical University, Shenyang 110016, China
| | - Masayuki Yamato
- Waseda University Joint Institution for Advanced Biomedical Sciences, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuju-ku, Tokyo 162-8666, Japan
| | - Hitomi Fujisaki
- Nippi Research Institute of Biomatrix, 520-11 Kuwabara, Toride, Ibaraki 302-0017, Japan
| | - Shunji Hattori
- Nippi Research Institute of Biomatrix, 520-11 Kuwabara, Toride, Ibaraki 302-0017, Japan
| | - Shin-Ichi Tashiro
- Department of Medical Education & Primary Care, Kyoto Prefectural University of Medicine, Kajiicho 465, Kamikyo-ku, Kyoto City, Kyoto 602-8566, Japan
| | - Takashi Ikejima
- China-Japan Research Institute of Medical and Pharmaceutical Sciences, Shenyang Pharmaceutical University, Shenyang 110016, China.
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Genetic Manipulation with Viral Vectors to Assess Metabolism and Adipose Tissue Function. Methods Mol Biol 2017; 1566:109-124. [PMID: 28244045 DOI: 10.1007/978-1-4939-6820-6_11] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Viral vectors have become widely used tools for genetic manipulation of adipose tissues to understand the biology and function of adipocytes in metabolism. There are a number of different viral vectors commonly used: retrovirus, lentivirus, adenovirus, and adeno-associated virus (AAV). Here, we review examples from the literature and describe methods to transduce adipocytes and adipose tissues using retrovirus, lentivirus, adenovirus, and AAV to ascertain gene function in adipose biology.
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Kim YH, Barclay JL, He J, Luo X, O'Neill HM, Keshvari S, Webster JA, Ng C, Hutley LJ, Prins JB, Whitehead JP. Identification of carboxypeptidase X (CPX)-1 as a positive regulator of adipogenesis. FASEB J 2016; 30:2528-40. [PMID: 27006448 DOI: 10.1096/fj.201500107r] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2015] [Accepted: 03/10/2016] [Indexed: 01/13/2023]
Abstract
Adipose tissue expansion occurs through a combination of hypertrophy of existing adipocytes and generation of new adipocytes via the process of hyperplasia, which involves the proliferation and subsequent differentiation of preadipocytes. Deficiencies in hyperplasia contribute to adipose tissue dysfunction and the association of obesity with chronic cardiometabolic diseases. Thus, increased understanding of hyperplastic pathways may be expected to afford novel therapeutic strategies. We have reported that fibroblast growth factor (FGF)-1 promotes proliferation and differentiation of human preadipocytes and recently demonstrated that bone morphogenetic protein and activin membrane-bound inhibitor (BAMBI) is a central, proximal effector. Herein, we describe the identification and characterization of carboxypeptidase X (CPX)-1, a secreted collagen-binding glycoprotein, as a novel downstream effector in human primary and Simpson-Golabi-Behmel syndrome preadipocytes. CPX-1 expression increased after treatment of preadipocytes with FGF-1, BAMBI knockdown, or induction of differentiation. CPX-1 knockdown compromised preadipocyte differentiation coincident with reduced collagen expression. Furthermore, preadipocytes differentiated on matrix derived from CPX-1 knockdown cells exhibited reduced Glut4 expression and insulin-stimulated glucose uptake. Finally, CPX-1 expression was increased in adipose tissue from obese mice and humans. Collectively, these findings establish CPX-1 as a positive regulator of adipogenesis situated downstream of FGF-1/BAMBI that may contribute to hyperplastic adipose tissue expansion via affecting extracellular matrix remodeling.-Kim, Y.-H., Barclay, J. L., He, J., Luo, X., O'Neill, H. M., Keshvari, S., Webster, J. A., Ng, C., Hutley, L. J., Prins, J. B., Whitehead, J. P. Identification of carboxypeptidase X (CPX)-1 as a positive regulator of adipogenesis.
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Affiliation(s)
- Yu-Hee Kim
- Metabolic Medicine Group, Mater Research Institute, University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Johanna L Barclay
- Metabolic Medicine Group, Mater Research Institute, University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Jingjing He
- Metabolic Medicine Group, Mater Research Institute, University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Xiao Luo
- Metabolic Medicine Group, Mater Research Institute, University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Hayley M O'Neill
- Metabolic Medicine Group, Mater Research Institute, University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Sahar Keshvari
- Metabolic Medicine Group, Mater Research Institute, University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Julie A Webster
- Metabolic Medicine Group, Mater Research Institute, University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Choaping Ng
- Metabolic Medicine Group, Mater Research Institute, University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Louise J Hutley
- Metabolic Medicine Group, Mater Research Institute, University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Johannes B Prins
- Metabolic Medicine Group, Mater Research Institute, University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
| | - Jonathan P Whitehead
- Metabolic Medicine Group, Mater Research Institute, University of Queensland, Translational Research Institute, Brisbane, Queensland, Australia
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Carboxypeptidase X-1 (CPX-1) is a secreted collagen-binding glycoprotein. Biochem Biophys Res Commun 2015; 468:894-9. [PMID: 26603934 DOI: 10.1016/j.bbrc.2015.11.053] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Accepted: 11/11/2015] [Indexed: 11/23/2022]
Abstract
Carboxypeptidase X-1 (CPX-1) is an atypical member of the carboxypeptidase (CP) family of proteins involved in a variety of physiological and pathological processes. However, unlike most other family members CPX-1 lacks catalytic activity making its biological function unclear. CPX-1 contains a 160 amino acid discoidin domain (DSD) that serves as a binding domain in other proteins prompting us to investigate a putative functional role for this domain in CPX-1. Sequence alignment confirmed the overarching homology between the DSD of CPX-1 and other DSDs whilst more detailed analysis revealed conservation of the residues known to form the collagen-binding trench within the DSD of the discoidin domain receptors (DDRs) 1 and 2. Biochemical characterisation of transiently expressed human CPX-1 revealed that CPX-1 was secreted in an N-glycosylation-dependent manner as treatment with the N-glycosylation inhibitor tunicamycin inhibited secretion concomitant with a reduction in CPX-1 mobility on Western blot. Using a collagen pull-down assay we found that secreted CPX-1 bound collagen and this appeared independent of N-glycosylation as treatment with PNGaseF did not affect binding. Further analysis under non-reducing and reducing (+DTT) conditions revealed that CPX-1 was secreted in both monomeric and dimeric forms and only the former bound collagen. Finally, mutation of a key residue situated within the putative collagen-binding trench within the DSD of CPX-1 (R192A) significantly reduced secretion and collagen-binding by 40% and 60%, respectively. Collectively these results demonstrate that CPX-1 is a secreted collagen-binding glycoprotein and provide a foundation for future studies investigating the function of CPX-1.
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DNA microarray analysis of genes differentially expressed in adipocyte differentiation. J Biosci 2014; 39:415-23. [DOI: 10.1007/s12038-014-9412-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
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Tumelty KE, Smith BD, Nugent MA, Layne MD. Aortic carboxypeptidase-like protein (ACLP) enhances lung myofibroblast differentiation through transforming growth factor β receptor-dependent and -independent pathways. J Biol Chem 2013; 289:2526-36. [PMID: 24344132 DOI: 10.1074/jbc.m113.502617] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Idiopathic pulmonary fibrosis (IPF) is a chronic and fatal lung disease characterized by the overgrowth, hardening, and scarring of lung tissue. The exact mechanisms of how IPF develops and progresses are unknown. IPF is characterized by extracellular matrix remodeling and accumulation of active TGFβ, which promotes collagen expression and the differentiation of smooth muscle α-actin (SMA)-positive myofibroblasts. Aortic carboxypeptidase-like protein (ACLP) is an extracellular matrix protein secreted by fibroblasts and myofibroblasts and is expressed in fibrotic human lung tissue and in mice with bleomycin-induced fibrosis. Importantly, ACLP knockout mice are significantly protected from bleomycin-induced fibrosis. The goal of this study was to identify the mechanisms of ACLP action on fibroblast differentiation. As primary lung fibroblasts differentiated into myofibroblasts, ACLP expression preceded SMA and collagen expression. Recombinant ACLP induced SMA and collagen expression in mouse and human lung fibroblasts. Knockdown of ACLP slowed the fibroblast-to-myofibroblast transition and partially reverted differentiated myofibroblasts by reducing SMA expression. We hypothesized that ACLP stimulates myofibroblast formation partly through activating TGFβ signaling. Treatment of fibroblasts with recombinant ACLP induced phosphorylation and nuclear translocation of Smad3. This phosphorylation and induction of SMA was dependent on TGFβ receptor binding and kinase activity. ACLP-induced collagen expression was independent of interaction with the TGFβ receptor. These findings indicate that ACLP stimulates the fibroblast-to-myofibroblast transition by promoting SMA expression via TGFβ signaling and promoting collagen expression through a TGFβ receptor-independent pathway.
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Affiliation(s)
- Kathleen E Tumelty
- From the Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118
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