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Clarke RA, Govindaraju H, Beretta M, Olzomer E, Lawther AJ, Walker AK, Fang Z, Eapen V, Hyams TC, Killingsworth M, Bridge W, Turner N, Siddiqui KS. Immp2l Enhances the Structure and Function of Mitochondrial Gpd2 Dehydrogenase. Int J Mol Sci 2024; 25:990. [PMID: 38256063 PMCID: PMC10815762 DOI: 10.3390/ijms25020990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 12/25/2023] [Accepted: 12/28/2023] [Indexed: 01/24/2024] Open
Abstract
'Inner mitochondrial membrane peptidase 2 like' (IMMP2L) is a nuclear-encoded mitochondrial peptidase that has been conserved through evolutionary history, as has its target enzyme, 'mitochondrial glycerol phosphate dehydrogenase 2' (GPD2). IMMP2L is known to cleave the mitochondrial transit peptide from GPD2 and another nuclear-encoded mitochondrial respiratory-related protein, cytochrome C1 (CYC1). However, it is not known whether IMMP2L peptidase activates or alters the activity or respiratory-related functions of GPD2 or CYC1. Previous investigations found compelling evidence of behavioural change in the Immp2lKD-/- KO mouse, and in this study, EchoMRI analysis found that the organs of the Immp2lKD-/- KO mouse were smaller and that the KO mouse had significantly less lean mass and overall body weight compared with wildtype littermates (p < 0.05). Moreover, all organs analysed from the Immp2lKD-/- KO had lower relative levels of mitochondrial reactive oxygen species (mitoROS). The kidneys of the Immp2lKD-/- KO mouse displayed the greatest decrease in mitoROS levels that were over 50% less compared with wildtype litter mates. Mitochondrial respiration was also lowest in the kidney of the Immp2lKD-/- KO mouse compared with other tissues when using succinate as the respiratory substrate, whereas respiration was similar to the wildtype when glutamate was used as the substrate. When glycerol-3-phosphate (G3P) was used as the substrate for Gpd2, we observed ~20% and ~7% respective decreases in respiration in female and male Immp2lKD-/- KO mice over time. Together, these findings indicate that the respiratory-related functions of mGpd2 and Cyc1 have been compromised to different degrees in different tissues and genders of the Immp2lKD-/- KO mouse. Structural analyses using AlphaFold2-Multimer further predicted that the interaction between Cyc1 and mitochondrial-encoded cytochrome b (Cyb) in Complex III had been altered, as had the homodimeric structure of the mGpd2 enzyme within the inner mitochondrial membrane of the Immp2lKD-/- KO mouse. mGpd2 functions as an integral component of the glycerol phosphate shuttle (GPS), which positively regulates both mitochondrial respiration and glycolysis. Interestingly, we found that nonmitochondrial respiration (NMR) was also dramatically lowered in the Immp2lKD-/- KO mouse. Primary mouse embryonic fibroblast (MEF) cell lines derived from the Immp2lKD-/- KO mouse displayed a ~27% decrease in total respiration, comprising a ~50% decrease in NMR and a ~12% decrease in total mitochondrial respiration, where the latter was consistent with the cumulative decreases in substrate-specific mediated mitochondrial respiration reported here. This study is the first to report the role of Immp2l in enhancing Gpd2 structure and function, mitochondrial respiration, nonmitochondrial respiration, organ size and homeostasis.
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Affiliation(s)
- Raymond A. Clarke
- Discipline of Psychiatry, University of New South Wales, Sydney, NSW 2052, Australia; (A.K.W.); (V.E.)
- Ingham Institute for Applied Medical Research, Sydney, NSW 2170, Australia; (Z.F.); (T.C.H.); (M.K.)
- Academic Unit of Infant Child and Adolescent Services (AUCS), South Western Sydney Local Health District, Liverpool, NSW 2170, Australia
| | - Hemna Govindaraju
- Department of Pharmacology, School of Biomedical Sciences, University of New South Wales, Sydney, NSW 2052, Australia; (H.G.); (N.T.)
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia
| | - Martina Beretta
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia; (M.B.); (E.O.); (W.B.)
| | - Ellen Olzomer
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia; (M.B.); (E.O.); (W.B.)
| | - Adam J. Lawther
- Laboratory of ImmunoPsychiatry, Neuroscience Research Australia, Randwick, NSW 2031, Australia;
| | - Adam K. Walker
- Discipline of Psychiatry, University of New South Wales, Sydney, NSW 2052, Australia; (A.K.W.); (V.E.)
- Laboratory of ImmunoPsychiatry, Neuroscience Research Australia, Randwick, NSW 2031, Australia;
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
| | - Zhiming Fang
- Ingham Institute for Applied Medical Research, Sydney, NSW 2170, Australia; (Z.F.); (T.C.H.); (M.K.)
| | - Valsamma Eapen
- Discipline of Psychiatry, University of New South Wales, Sydney, NSW 2052, Australia; (A.K.W.); (V.E.)
- Ingham Institute for Applied Medical Research, Sydney, NSW 2170, Australia; (Z.F.); (T.C.H.); (M.K.)
- Academic Unit of Infant Child and Adolescent Services (AUCS), South Western Sydney Local Health District, Liverpool, NSW 2170, Australia
| | - Tzipi Cohen Hyams
- Ingham Institute for Applied Medical Research, Sydney, NSW 2170, Australia; (Z.F.); (T.C.H.); (M.K.)
| | - Murray Killingsworth
- Ingham Institute for Applied Medical Research, Sydney, NSW 2170, Australia; (Z.F.); (T.C.H.); (M.K.)
- NSW Health Pathology, Liverpool Hospital Campus, Liverpool, NSW 2107, Australia
| | - Wallace Bridge
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia; (M.B.); (E.O.); (W.B.)
| | - Nigel Turner
- Department of Pharmacology, School of Biomedical Sciences, University of New South Wales, Sydney, NSW 2052, Australia; (H.G.); (N.T.)
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia
| | - Khawar Sohail Siddiqui
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia; (M.B.); (E.O.); (W.B.)
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Lawther AJ, Zieba J, Fang Z, Furlong TM, Conn I, Govindaraju H, Choong LLY, Turner N, Siddiqui KS, Bridge W, Merlin S, Hyams TC, Killingsworth M, Eapen V, Clarke RA, Walker AK. Antioxidant Behavioural Phenotype in the Immp2l Gene Knock-Out Mouse. Genes (Basel) 2023; 14:1717. [PMID: 37761857 PMCID: PMC10531238 DOI: 10.3390/genes14091717] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 08/16/2023] [Accepted: 08/21/2023] [Indexed: 09/29/2023] Open
Abstract
Mitochondrial dysfunction is strongly associated with autism spectrum disorder (ASD) and the Inner mitochondrial membrane protein 2-like (IMMP2L) gene is linked to autism inheritance. However, the biological basis of this linkage is unknown notwithstanding independent reports of oxidative stress in association with both IMMP2L and ASD. To better understand IMMP2L's association with behaviour, we developed the Immp2lKD knockout (KO) mouse model which is devoid of Immp2l peptidase activity. Immp2lKD -/- KO mice do not display any of the core behavioural symptoms of ASD, albeit homozygous Immp2lKD -/- KO mice do display increased auditory stimulus-driven instrumental behaviour and increased amphetamine-induced locomotion. Due to reports of increased ROS and oxidative stress phenotypes in an earlier truncated Immp2l mouse model resulting from an intragenic deletion within Immp2l, we tested whether high doses of the synthetic mitochondrial targeted antioxidant (MitoQ) could reverse or moderate the behavioural changes in Immp2lKD -/- KO mice. To our surprise, we observed that ROS levels were not increased but significantly lowered in our new Immp2lKD -/- KO mice and that these mice had no oxidative stress-associated phenotypes and were fully fertile with no age-related ataxia or neurodegeneration as ascertained using electron microscopy. Furthermore, the antioxidant MitoQ had no effect on the increased amphetamine-induced locomotion of these mice. Together, these findings indicate that the behavioural changes in Immp2lKD -/- KO mice are associated with an antioxidant-like phenotype with lowered and not increased levels of ROS and no oxidative stress-related phenotypes. This suggested that treatments with antioxidants are unlikely to be effective in treating behaviours directly resulting from the loss of Immp2l/IMMP2L activity, while any behavioural deficits that maybe associated with IMMP2L intragenic deletion-associated truncations have yet to be determined.
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Affiliation(s)
- Adam J. Lawther
- Laboratory of ImmunoPsychiatry, Neuroscience Research Australia, Randwick, NSW 2031, Australia
| | - Jerzy Zieba
- Laboratory of ImmunoPsychiatry, Neuroscience Research Australia, Randwick, NSW 2031, Australia
- Department of Psychology, University of Rzeszow, 35-310 Rzeszow, Poland
| | - Zhiming Fang
- Discipline of Psychiatry and Mental Health, University of New South Wales, Sydney, NSW 2052, Australia
- Ingham Institute for Applied Medical Research, Sydney, NSW 2170, Australia; (T.C.H.)
| | - Teri M. Furlong
- School of Biomedical Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Illya Conn
- Laboratory of ImmunoPsychiatry, Neuroscience Research Australia, Randwick, NSW 2031, Australia
- Schizophrenia Research Laboratory, Neuroscience Research Australia, Randwick, NSW 2031, Australia
| | - Hemna Govindaraju
- Department of Pharmacology, School of Biomedical Sciences, University of New South Wales, Sydney, NSW 2052, Australia
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia
| | - Laura L. Y. Choong
- Department of Pharmacology, School of Biomedical Sciences, University of New South Wales, Sydney, NSW 2052, Australia
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia
| | - Nigel Turner
- Department of Pharmacology, School of Biomedical Sciences, University of New South Wales, Sydney, NSW 2052, Australia
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia
| | - Khawar Sohail Siddiqui
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Wallace Bridge
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, NSW 2052, Australia
| | - Sam Merlin
- Medical Science, School of Science, Western Sydney University, Campbelltown, Sydney, NSW 2751, Australia
| | - Tzipi Cohen Hyams
- Ingham Institute for Applied Medical Research, Sydney, NSW 2170, Australia; (T.C.H.)
| | - Murray Killingsworth
- Ingham Institute for Applied Medical Research, Sydney, NSW 2170, Australia; (T.C.H.)
- NSW Health Pathology, Liverpool Hospital Campus, 1 Campbell Street, Liverpool, NSW 2107, Australia
| | - Valsamma Eapen
- Discipline of Psychiatry and Mental Health, University of New South Wales, Sydney, NSW 2052, Australia
- Ingham Institute for Applied Medical Research, Sydney, NSW 2170, Australia; (T.C.H.)
- Academic Unit of Infant Child and Adolescent Services (AUCS), South Western Sydney Local Health District, Liverpool, NSW 2170, Australia
| | - Raymond A. Clarke
- Discipline of Psychiatry and Mental Health, University of New South Wales, Sydney, NSW 2052, Australia
- Ingham Institute for Applied Medical Research, Sydney, NSW 2170, Australia; (T.C.H.)
- Academic Unit of Infant Child and Adolescent Services (AUCS), South Western Sydney Local Health District, Liverpool, NSW 2170, Australia
| | - Adam K. Walker
- Laboratory of ImmunoPsychiatry, Neuroscience Research Australia, Randwick, NSW 2031, Australia
- Discipline of Psychiatry and Mental Health, University of New South Wales, Sydney, NSW 2052, Australia
- Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
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