Analyzing Mitochondrial Function in a Drosophila melanogaster PINK1B9-Null Mutant Using High-resolution Respirometry

Summary

Here we present a high-resolution respirometry protocol to analyze bioenergetics in PINK1^B9-null mutant fruit flies. The method uses the Substrate-Uncoupler-Inhibitor-Titration (SUIT) protocol.

Abstract

Neurodegenerative diseases, including Parkinson's Disease (PD), and cellular disturbances such as cancer are some of the disorders that disrupt energy metabolism with impairment of mitochondrial functions. Mitochondria are organelles that control both energy metabolism and cellular processes involved in cell survival and death. For this reason, approaches to evaluate mitochondrial function can offer important insights into cellular conditions in pathological and physiological processes. In this regard, high-resolution respirometry (HRR) protocols allow evaluation of the whole mitochondrial respiratory chain function or the activity of specific mitochondrial complexes. Furthermore, studying mitochondrial physiology and bioenergetics requires genetically and experimentally tractable models such as Drosophila melanogaster.

This model presents several advantages, such as its similarity to human physiology, its rapid life cycle, easy maintenance, cost-effectiveness, high throughput capabilities, and a minimized number of ethical concerns. These attributes collectively establish it as an invaluable tool for dissecting complex cellular processes. The present work explains how to analyze mitochondrial function using the Drosophila melanogaster PINK1^B9-null mutant. The pink1 gene is responsible for encoding PTEN-induced putative kinase 1, through a process recognized as mitophagy, which is crucial for the removal of dysfunctional mitochondria from the mitochondrial network. Mutations in this gene have been associated with an autosomal recessive early-onset familial form of PD. This model can be used to study mitochondrial dysfunction involved in the pathophysiology of PD.

Introduction

Mitochondria are cellular organelles that control important functions, including apoptotic regulation, calcium homeostasis, and participation in biosynthetic pathways. By possessing autonomous genetic material, they are capable of contributing to cellular maintenance and repair processes. Their structure houses the electron transport chain and oxidative phosphorylation, both crucial for cellular energy^1,2,3. In particular, energy control is achieved through adenosine triphosphate (ATP) production via oxidative phosphorylation (OXPHOS)². Disruption of e....

Protocol

We used the strains w¹¹¹⁸ (white) and w[*] Pink1[B9]/FM7i, P{w[+mC]=ActGFP}JMR3 (referred to as Pink1^B9) (FlyBase ID: FBgn0029891) from the Bloomington Drosophila stock center (ID number: 34749). In this study, male D. melanogaster PINK1^B9-null mutants are compared with male D. melanogaster from the w¹¹¹⁸ strain, which is used as a control group (genetic background). Other parameters must be analyzed concomitantly with the respi.......

Discussion

HRR is a powerful technique for studying mitochondrial respiration and energy metabolism in D. melanogaster and other organisms. It provides a detailed and quantitative assessment of mitochondrial function, allowing researchers to gain insights into the bioenergetics of the cells. The protocol presented here describes the evaluation of mitochondrial respiratory chain function and the activity of specific mitochondrial complexes using the SUIT protocol in D. melanogaster. The SUIT protocol involves syste.......

Materials

Name	Company	Catalog Number	Comments
ADP	Sigma-Aldrich	A5285	Adenosine 5′-diphosphate sodium sal (CAS number 72696-48-1); ≥95%; molecular weight = 501.31 g/mol.
Ágar	Kasv	K25-1800	For bacteriologal use
Antimycin-A	Sigma-Aldrich	A8674	Antimycin A from Streptomyces sp. (CAS number 1397-94-0); molecular weight  540 g/mol;
Bovine Serum Albumin (BSA)	Sigma-Aldrich	A7030	Bovine Serum Albumin (CAS number 9048-46-8); pH 7,0 ≥ 98%
Datlab software	Oroboros Instruments, Innsbruck, Austria	20700	Software for data acquisition and analysis
Digitonin	Sigma-Aldrich	D 5628	CAS number 11024-24-1
Distilled water
Drosophila melanogaster strain w[*] Pink1[B9]/FM7i, P{w[+mC]=ActGFP}JMR3			Obtained from Bloomington Drosophila stock center
Drosophila melanogaster strain w1118			Obtained  from the Federal University of Santa Maria
EGTA	Sigma-Aldrich	E8145	Ethylene glycol-bis(2-aminoethylether)-N,N,N',N'-tetraacetic acid (CAS number 13638-13-3); ≥97%; molecular weight =468.28 g/mol
FCCP	Sigma-Aldrich	C2920	Carbonyl cyanide 4- (trifluoromethoxy)phenylhydrazone  (CAS number 370-86-5); ≥98% (TLC), powder
GraphPad Prism version 8.0.1.			Software for data acquisition and analysis
Hepes	Sigma-Aldrich	H4034	4-(2-Hydroxyethyl)piperazine-1-ethanesulfonic acid (CAS number 7365-45-9); ≥99,5% (titration), cell cultured tested; molecular weight = 238.30 g/mol
High-resolution respirometer Oxygraph O2K	Oroboros Instruments, Innsbruck, Austria	10022-02	Startup O2K respirometer kit
KH2PO4	Sigma-Aldrich	P5379	Monopotassium phosphate (CAS number 7778-77-0); Reagente Plus, molecular weigt = 136.09 g/mol
KOH	Sigma-Aldrich	211473	Potassium hydroxide (CAS number 1310-58-3); ACS reagent, ≥85%, pellets
Malate	Sigma-Aldrich	M1296	Malonic acid (CAS number 141-82-2); 99%, molecular weight = 104.06 g/mol). A solution is pH adjusted to approximately 7.0.
Malic acid	Sigma-Aldrich	M1000	(S)-(−)-2-Hydroxysuccinic acid (CAS number 97-67-6); ≥95% ; molecular weight = 134.09 g/mol
MES	Sigma-Aldrich	M3671	2-(N-Morpholino)ethanesulfonic acid (CAS number 4432-31-9); ≥99% (titration); molecular weight = 195.24 g/mol
MgCl2	Sigma-Aldrich	M8266	Magnesium chloride (CAS number 7786-30-3); anhydrous, ≥98%, molecular weight = 95.21 g/mol
Microcentrifuge tubes	Eppendorf
O2K-Titration Set	Oroboros Instruments, Innsbruck, Austria	20820-03	Hamilton syringes with different volumes
Oligomycin	Sigma-Aldrich	O 4876	Oligomycin from Streptomyces diastatochromogenes (CAS number  1404-19-9); ≥90% total oligomycins basis (HPLC)
Pistil to homogenization
Proline	Sigma-Aldrich	P0380	L-Proline (CAS number 147-85-3); powder; 99%; molecular weight = 115.13 g/mol
Pyruvate	Sigma-Aldrich	P2256	Sodium pyruvate (CAS number 113-24-6), ≥99%; molecular weight = 110.04 g/mol
Rotenone	Sigma-Aldrich	R8875	Rotetone (CAS number 83-79-4); ≥95%, molecular weight 394.42 g/ mol
Succinate	Sigma-Aldrich	S 2378	Sodium succinate dibasic hexahydrate (CAS number 6106-21-4); ≥99%
Sucrose	Merck	107,651,000	Sucrose for microbiology use (CAS number 57-50-1)
Taurine	Sigma-Aldrich	T0625	CAS number 107-35-7