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Morgan NE, Cutrona MB, Simpson JC. Multitasking Rab Proteins in Autophagy and Membrane Trafficking: A Focus on Rab33b. Int J Mol Sci 2019; 20:ijms20163916. [PMID: 31408960 PMCID: PMC6719199 DOI: 10.3390/ijms20163916] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Revised: 07/30/2019] [Accepted: 08/09/2019] [Indexed: 12/25/2022] Open
Abstract
Autophagy (particularly macroautophagy) is a bulk degradation process used by eukaryotic cells in order to maintain adequate energy levels and cellular homeostasis through the delivery of long-lived proteins and organelles to the lysosome, resulting in their degradation. It is becoming increasingly clear that many of the molecular requirements to fulfil autophagy intersect with those of conventional and unconventional membrane trafficking pathways. Of particular interest is the dependence of these processes on multiple members of the Rab family of small GTP binding proteins. Rab33b is a protein that localises to the Golgi apparatus and has suggested functions in both membrane trafficking and autophagic processes. Interestingly, mutations in the RAB33B gene have been reported to cause the severe skeletal disorder, Smith–McCort Dysplasia; however, the molecular basis for Rab33b in this disorder remains to be determined. In this review, we focus on the current knowledge of the participation of Rab33b and its interacting partners in membrane trafficking and macroautophagy, and speculate on how its function, and dysfunction, may contribute to human disease.
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Affiliation(s)
- Niamh E Morgan
- School of Biology and Environmental Science & Conway Institute of Biomolecular and Biomedical Research, University College Dublin (UCD), D04 N2E5 Dublin, Ireland
| | - Meritxell B Cutrona
- School of Biology and Environmental Science & Conway Institute of Biomolecular and Biomedical Research, University College Dublin (UCD), D04 N2E5 Dublin, Ireland
| | - Jeremy C Simpson
- School of Biology and Environmental Science & Conway Institute of Biomolecular and Biomedical Research, University College Dublin (UCD), D04 N2E5 Dublin, Ireland.
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Huang L, Urasaki A, Inagaki N. Rab33a and Rab33ba mediate the outgrowth of forebrain commissural axons in the zebrafish brain. Sci Rep 2019; 9:1799. [PMID: 30755680 PMCID: PMC6372587 DOI: 10.1038/s41598-018-38468-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 12/19/2018] [Indexed: 12/20/2022] Open
Abstract
Rab small GTPases play key roles in intracellular membrane trafficking. Rab33a promotes axon outgrowth of cultured rat hippocampal neurons by mediating the anterograde axonal transport of Golgi-derived vesicles and the concomitant exocytosis of these vesicles at the growth cone. However, the functions of Rab33 in vivo are unclear. Here, we show that zebrafish rab33a and rab33ba are orthologs of mammalian Rab33a and Rab33b, respectively. They are expressed in the developing brain, including in neurons of the telencephalic dorsorostral cluster and the diencephalic ventrorostral cluster, which project axons to form the anterior and postoptic commissures, respectively. Although rab33a single mutant and rab33ba single mutant fish did not show remarkable defects, fish carrying the rab33a;rab33ba double mutations displayed dysgenesis of the anterior and postoptic commissures. Single-cell labeling in the telencephalic dorsorostral cluster demonstrated that the rab33a;rab33ba double mutation inhibits axonal extension in the anterior commissure. These results suggest that Rab33a and Rab33ba mediate axon outgrowth and the formation of the forebrain commissures in the zebrafish brain in a cooperative manner.
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Affiliation(s)
- Liguo Huang
- Laboratory of Systems Neurobiology and Medicine, Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan
| | - Akihiro Urasaki
- Laboratory of Systems Neurobiology and Medicine, Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan
| | - Naoyuki Inagaki
- Laboratory of Systems Neurobiology and Medicine, Division of Biological Science, Nara Institute of Science and Technology, Ikoma, Nara, 630-0192, Japan.
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Suzuki A, Iwata J. Molecular Regulatory Mechanism of Exocytosis in the Salivary Glands. Int J Mol Sci 2018; 19:E3208. [PMID: 30336591 PMCID: PMC6214078 DOI: 10.3390/ijms19103208] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 10/10/2018] [Accepted: 10/11/2018] [Indexed: 12/12/2022] Open
Abstract
Every day, salivary glands produce about 0.5 to 1.5 L of saliva, which contains salivary proteins that are essential for oral health. The contents of saliva, 0.3% proteins (1.5 to 4.5 g) in fluid, help prevent oral infections, provide lubrication, aid digestion, and maintain oral health. Acinar cells in the lobular salivary glands secrete prepackaged secretory granules that contain salivary components such as amylase, mucins, and immunoglobulins. Despite the important physiological functions of salivary proteins, we know very little about the regulatory mechanisms of their secretion via exocytosis, which is a process essential for the secretion of functional proteins, not only in salivary glands, but also in other secretory organs, including lacrimal and mammary glands, the pancreas, and prostate. In this review, we discuss recent findings that elucidate exocytosis by exocrine glands, especially focusing on the salivary glands, in physiological and pathological conditions.
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Affiliation(s)
- Akiko Suzuki
- Department of Diagnostic & Biomedical Sciences, The University of Texas Health Science Center at Houston School of Dentistry, Houston, TX 77054, USA.
- Center for Craniofacial Research, The University of Texas Health Science Center at Houston School of Dentistry, Houston, TX 77054, USA.
| | - Junichi Iwata
- Department of Diagnostic & Biomedical Sciences, The University of Texas Health Science Center at Houston School of Dentistry, Houston, TX 77054, USA.
- Center for Craniofacial Research, The University of Texas Health Science Center at Houston School of Dentistry, Houston, TX 77054, USA.
- Program of Biochemistry and Cell Biology, The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, TX 77030, USA.
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Banworth MJ, Li G. Consequences of Rab GTPase dysfunction in genetic or acquired human diseases. Small GTPases 2018. [PMID: 29239692 DOI: 10.1080/215412481397833] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2023] Open
Abstract
Rab GTPases are important regulators of intracellular membrane trafficking in eukaryotes. Both activating and inactivating mutations in Rab genes have been identified and implicated in human diseases ranging from neurological disorders to cancer. In addition, altered Rab expression is often associated with disease prognosis. As such, the study of diseases associated with Rabs or Rab-interacting proteins has shed light on the important role of intracellular membrane trafficking in disease etiology. In this review, we cover recent advances in the field with an emphasis on cellular mechanisms.
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Affiliation(s)
- Marcellus J Banworth
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
| | - Guangpu Li
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
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Saitoh E, Sega T, Imai A, Isemura S, Kato T, Ochiai A, Taniguchi M. The PBII gene of the human salivary proline-rich protein P-B produces another protein, Q504X8, with an opiorphin homolog, QRGPR. Arch Oral Biol 2018; 88:10-18. [PMID: 29339256 DOI: 10.1016/j.archoralbio.2018.01.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 01/09/2018] [Accepted: 01/09/2018] [Indexed: 12/27/2022]
Abstract
OBJECTIVES The NCBI gene database and human-transcriptome database for alternative splicing were used to determine the expression of mRNAs for P-B (SMR3B) and variant form of P-B. The translational product from the former mRNA was identified as the protein named P-B, whereas that from the latter has not yet been elucidated. In the present study, we investigated the expression of P-B and its variant form at the protein level. DESIGN To identify the variant protein of P-B, (1) cationic proteins with a higher isoelectric point in human pooled whole saliva were purified by a two dimensional liquid chromatography; (2) the peptide fragments generated from the in-solution of all proteins digested with trypsin separated and analyzed by MALDI-TOF-MS; and (3) the presence or absence of P-B in individual saliva was examined by 15% SDS-PAGE. RESULTS The peptide sequences (I37PPPYSCTPNMNNCSR52, C53HHHHKRHHYPCNYCFCYPK72, R59HHYPCNYCFCYPK72 and H60HYPCNYCFCYPK72) present in the variant protein of P-B were identified. The peptide sequence (G6PYPPGPLAPPQPFGPGFVPPPPPPPYGPGR36) in P-B (or the variant) and sequence (I37PPPPPAPYGPGIFPPPPPQP57) in P-B were identified. The sum of the sequences identified indicated a 91.23% sequence identity for P-B and 79.76% for the variant. There were cases in which P-B existed in individual saliva, but there were cases in which it did not exist in individual saliva. CONCLUSIONS The variant protein is produced by excising a non-canonical intron (CC-AC pair) from the 3'-noncoding sequence of the PBII gene. Both P-B and the variant are subject to proteolysis in the oral cavity.
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Affiliation(s)
- Eiichi Saitoh
- Graduate School of Technology, Niigata Institute of Technology, Niigata 945-1195, Japan.
| | - Takuya Sega
- Graduate School of Technology, Niigata Institute of Technology, Niigata 945-1195, Japan
| | - Akane Imai
- Department of Dental Hygiene, The Nippon Dental University College at Niigata, Niigata 951-8580, Japan
| | - Satoko Isemura
- Department of Dental Hygiene, The Nippon Dental University College at Niigata, Niigata 951-8580, Japan
| | - Tetsuo Kato
- Laboratory of Chemistry, Tokyo Dental College, Tokyo 101-0062, Japan
| | - Akihito Ochiai
- Department of Materials Science and Technology, Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan
| | - Masayuki Taniguchi
- Department of Materials Science and Technology, Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan
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Banworth MJ, Li G. Consequences of Rab GTPase dysfunction in genetic or acquired human diseases. Small GTPases 2017; 9:158-181. [PMID: 29239692 DOI: 10.1080/21541248.2017.1397833] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Rab GTPases are important regulators of intracellular membrane trafficking in eukaryotes. Both activating and inactivating mutations in Rab genes have been identified and implicated in human diseases ranging from neurological disorders to cancer. In addition, altered Rab expression is often associated with disease prognosis. As such, the study of diseases associated with Rabs or Rab-interacting proteins has shed light on the important role of intracellular membrane trafficking in disease etiology. In this review, we cover recent advances in the field with an emphasis on cellular mechanisms.
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Affiliation(s)
- Marcellus J Banworth
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
| | - Guangpu Li
- a Department of Biochemistry and Molecular Biology , University of Oklahoma Health Sciences Center , Oklahoma City , OK , USA
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RAB37 interacts directly with ATG5 and promotes autophagosome formation via regulating ATG5-12-16 complex assembly. Cell Death Differ 2017; 25:918-934. [PMID: 29229996 PMCID: PMC5943352 DOI: 10.1038/s41418-017-0023-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 10/24/2017] [Accepted: 10/24/2017] [Indexed: 02/07/2023] Open
Abstract
Intracellular membrane trafficking is essential for eukaryotic cell existence. Here, we show that RAB37 activation through GTP binding recruits ATG5-12 to isolation membrane and promotes autophagosome formation through the ATG5-ATG12-ATG16L1 complex. RAB37 is localized on the isolation membrane. It can bind directly with ATG5 and promotes formation of the ATG5-12-16 complex. Mutation analysis reveals that GTP-bound RAB37 exhibits an enhanced interaction with ATG5-12 and GDP-stabilised mutation impairs the interaction. RAB37 promotes ATG5-12 interaction with ATG16L1, thus facilitates lipidation of LC3B in a GTP-dependent manner to enhance autophagy. Notably, ablation of RAB37 expression affects the complex formation and decreases autophagy, whereas forced RAB37 expression promotes autophagy and also suppresses cell proliferation. Our results demonstrate a role of RAB37 in autophagosome formation through a molecular connection of RAB37, ATG5-12, ATG16L1 up to LC3B, suggesting an organiser role of RAB37 during autophagosomal membrane biogenesis. These findings have broad implications for understanding the role of RAB vesicle transport in autophagy and cancer.
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Gomi H, Osawa H, Uno R, Yasui T, Hosaka M, Torii S, Tsukise A. Canine Salivary Glands: Analysis of Rab and SNARE Protein Expression and SNARE Complex Formation With Diverse Tissue Properties. J Histochem Cytochem 2017; 65:637-653. [PMID: 28914590 DOI: 10.1369/0022155417732527] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The comparative structure and expression of salivary components and vesicular transport proteins in the canine major salivary glands were investigated. Histochemical analysis revealed that the morphology of the five major salivary glands-parotid, submandibular, polystomatic sublingual, monostomatic sublingual, and zygomatic glands-was greatly diverse. Immunoblot analysis revealed that expression levels of α-amylase and antimicrobial proteins, such as lysozyme, lactoperoxidase, and lactoferrin, differed among the different glands. Similarly, Rab proteins (Rab3d, Rab11a, Rab11b, Rab27a, and Rab27b) and soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptor (SNARE) proteins VAMP4, VAMP8, syntaxin-2, syntaxin-3, syntaxin-4, and syntaxin-6 were expressed at various levels in individual glands. mmunohistochemistry of Rab3d, Rab11b, Rab27b, VAMP4, VAMP8, syntaxin-4, and syntaxin-6 revealed their predominant expression in serous acinar cells, demilunes, and ductal cells. The VAMP4/syntaxin-6 SNARE complex, which is thought to be involved in the maturation of secretory granules in the Golgi field, was found more predominantly in the monostomatic sublingual gland than in the parotid gland. These results suggest that protein expression profiles in canine salivary glands differ among individual glands and reflect the properties of their specialized functions.
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Affiliation(s)
- Hiroshi Gomi
- Department of Veterinary Anatomy, College of Bioresource Sciences, Nihon University, Fujisawa, Japan
| | - Hiromi Osawa
- Department of Veterinary Anatomy, College of Bioresource Sciences, Nihon University, Fujisawa, Japan
| | - Rie Uno
- Department of Veterinary Anatomy, College of Bioresource Sciences, Nihon University, Fujisawa, Japan
| | - Tadashi Yasui
- Department of Veterinary Anatomy, College of Bioresource Sciences, Nihon University, Fujisawa, Japan
| | - Masahiro Hosaka
- Laboratory of Molecular Life Sciences, Department of Biotechnology, Akita Prefectural University, Akita, Japan
| | - Seiji Torii
- Laboratory of Secretion Biology, Institute for Molecular and Cellular Regulation, Gunma University, Maebashi, Japan
| | - Azuma Tsukise
- Department of Veterinary Anatomy, College of Bioresource Sciences, Nihon University, Fujisawa, Japan
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The small GTPase, Rab27, and its effectors and regulators participate in granule exocytosis by parotid acinar cells. J Oral Biosci 2017. [DOI: 10.1016/j.job.2016.10.003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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