Page last updated: 2024-10-24

G2/MI transition of meiotic cell cycle

Definition

Target type: biologicalprocess

The cell cycle process in which a cell progresses from meiotic G2 phase to M phase of meiosis I. [PMID:15084480]

The G2/M transition in the meiotic cell cycle represents a critical checkpoint that ensures proper chromosome duplication and alignment before the cell commits to division. This transition is orchestrated by a complex interplay of regulatory proteins, particularly cyclin-dependent kinases (CDKs) and their regulatory subunits, cyclins.

**1. Activation of CDK1:**
The key player in the G2/M transition is CDK1, also known as the maturation promoting factor (MPF). It remains inactive throughout G2 phase but becomes activated in response to rising levels of cyclin B. The binding of cyclin B to CDK1 forms the active MPF complex.

**2. Phosphorylation of Key Substrates:**
Activated MPF initiates a cascade of phosphorylation events targeting specific proteins involved in chromosome condensation, nuclear envelope breakdown, spindle assembly, and activation of other downstream signaling pathways.

**3. Chromosome Condensation:**
MPF-mediated phosphorylation of condensin proteins, a complex of proteins responsible for packaging DNA into compact chromosomes, triggers the condensation of replicated chromosomes. This allows for efficient segregation during meiosis.

**4. Nuclear Envelope Breakdown (NEBD):**
MPF also phosphorylates lamins, proteins that make up the nuclear lamina, causing the nuclear envelope to fragment. This allows the chromosomes to attach to the mitotic spindle.

**5. Spindle Assembly:**
MPF phosphorylation of various spindle components, such as microtubule-associated proteins, promotes microtubule polymerization and spindle formation. The spindle apparatus, composed of microtubules, will eventually pull sister chromatids apart during meiosis.

**6. Checkpoint Regulation:**
The G2/M transition is tightly regulated by a checkpoint mechanism that ensures proper chromosome duplication and alignment. If errors are detected, the checkpoint machinery halts the cell cycle and activates repair pathways.

**7. Meiosis-Specific Features:**
Meiosis is characterized by two rounds of division, producing four haploid gametes from a single diploid cell. During the first meiotic division (Meiosis I), homologous chromosomes pair up and exchange genetic material through a process called crossing over. This genetic recombination increases genetic diversity. MPF activity plays a key role in regulating this complex process.

**8. Entry into Meiosis I:**
The G2/M transition initiates the first meiotic division, leading to the separation of homologous chromosomes. The transition into meiosis II, the second division, is regulated by a similar mechanism involving a second wave of MPF activation.

**9. Exit from Meiosis:**
After the completion of meiosis II, MPF activity is downregulated, allowing the cell to exit meiosis and enter a quiescent state until fertilization occurs.'
"

Proteins (1)

ProteinDefinitionTaxonomy
G2/mitotic-specific cyclin-B2A G2/mitotic-specific cyclin-B2 that is encoded in the genome of human. [PRO:DNx, UniProtKB:O95067]Homo sapiens (human)

Compounds (51)

CompoundDefinitionClassesRoles
bisindolylmaleimide ibisindolylmaleimide I: a bis(indolyl)maleimide
bisindolylmaleimide ivindoles;
maleimides
boheminebohemine : Purine substituted on C-2, C-6 and N-9 with (3-hydroxypropyl)amino, benzylamino and isopropyl groups respectively; a synthetic, cell-permeable, cyclin-dependent kinase (CDK) inhibitor that is structurally similar to olomoucine and roscovitine.purinesEC 2.7.11.22 (cyclin-dependent kinase) inhibitor
indirubin-3'-monoximeindirubin-3'-monoxime : A member of the class of biindoles that is indirubin in which the keto group at position 3' has undergone condensation with hydroxylamine to form the corresponding oxime.

indirubin-3'-monoxime: has antiangiogenic activity
nsc 664704kenpaullone : An indolobenzazepine that is paullone in which the hydrogen at position 9 is replaced by a bromo substituent. It is an ATP-competitive inhibitor of cyclin-dependent kinases (CDKs) and glycogen synthase kinase 3beta (GSK3beta).

kenpaullone: inhibits CDK1/cyclin B; structure in first source
indolobenzazepine;
lactam;
organobromine compound
cardioprotective agent;
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor;
EC 2.7.11.26 (tau-protein kinase) inhibitor;
geroprotector
nu2058NU2058: structure in first source
nu6102NU6102: structure in first source
olomoucineolomoucine : A 9H-purine that is substituted by a (2-hydroxyethyl)nitrilo, benzylnitrilo and a methyl group at positions 2,6 and 9, respectively. It is a cyclin-dependent kinase inhibitor.

olomoucine: inhibits protein P34CDC2
2,6-diaminopurines;
ethanolamines
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor
indirubin
indigohydroxyindoles
2-phenylindolealpha-phenylindole: RN given refers to parent cpdphenylindole
staurosporineindolocarbazole alkaloid;
organic heterooctacyclic compound
apoptosis inducer;
bacterial metabolite;
EC 2.7.11.13 (protein kinase C) inhibitor;
geroprotector
cyc 202seliciclib : 2,6-Diaminopurine carrying benzylamino, (2R)-1-hydroxybutan-2-yl and isopropyl substituents at C-6, C-2-N and N-9 respectively. It is an experimental drug candidate in the family of pharmacological cyclin-dependent kinase (CDK) inhibitors.2,6-diaminopurinesantiviral drug;
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor
sb 216763indoles;
maleimides
paullonepaullone : An indolobenzazepine that is 5,6,7,12-tetrahydroindolo[3,2-d][1]benzazepine carrying an oxo substituent at position 6.

paullone: structure in first source
indolobenzazepine;
lactam
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor;
EC 2.7.11.26 (tau-protein kinase) inhibitor
nu 6027
meridianin gmeridianin G: from the tunicate Aplidium meridianum; structure in first source
5-iodoindirubin-3'-monoxime5-iodoindirubin-3'-monoxime: inhibits GSK-3beta
7-n-butyl-6-(4'-hydroxyphenyl)-5h-pyrrolo(2,3b)pyrazine
6-bromoindirubin-3'-oxime6-bromoindirubin-3'-oxime : A member of the class of biindoles that is indirubin substituted at position 6 by a bromo group and in which the keto group at position 3' has undergone condensation with hydroxylamine to form the corresponding oxime.

6-bromoindirubin-3'-oxime: structure in first source
purvalanol bpurvalanol B: protein kinase inhibitor; structure in first sourcepurvalanolprotein kinase inhibitor
purvalanol a6-((3-chloro)anilino)-2-(isopropyl-2-hydroxyethylamino)-9-isopropylpurine: purvalanol A is the (1R)-isomer;purvalanol
cgp 60474substituted aniline
bms 387032N-(5-(((5-(1,1-dimethylethyl)-2-oxazolyl)methyl)thio)-2-thiazolyl)-4-piperidinecarboxamide: a CDK2 inhibitor with antineoplastic activity; structure in first source

N-(5-{[(5-tert-butyl-1,3-oxazol-2-yl)methyl]sulfanyl}-1,3-thiazol-2-yl)piperidine-4-carboxamide : A secondary carboxamide resulting from the formal condensation of the carboxy group of piperidine-4-carboxylic acid with the amino group of 5-{[(5-tert-butyl-1,3-oxazol-2-yl)methyl]sulfanyl}-1,3-thiazol-2-amine. It is an ATP-competitive inhibitor of CDK2, CDK7 and CDK9 kinases and exhibits anti-cancer properties.
1,3-oxazoles;
1,3-thiazoles;
organic sulfide;
piperidinecarboxamide;
secondary carboxamide
angiogenesis inhibitor;
antineoplastic agent;
apoptosis inducer;
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor
7-butyl-6-(4-methoxyphenyl)-5H-pyrrolo[2,3-b]pyrazinepyrroles
4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione4-benzyl-2-methyl-1,2,4-thiadiazolidine-3,5-dione: a GSK3beta inhibitor

TDZD-8 : A member of the class of thiadiazolidines that is 1,2,4-thiadiazolidine-3,5-dione which is substituted by a methyl group at position 2 and by a benzyl group at position 4. It is a non-ATP competitive inhibitor of glycogen synthase kinase 3beta (GSK3beta). An experimental compound which was being developed for the potential treatment of Alzheimer's disease.
benzenes;
thiadiazolidine
anti-inflammatory agent;
antineoplastic agent;
apoptosis inducer;
EC 2.7.11.26 (tau-protein kinase) inhibitor;
neuroprotective agent
sb 4152863-(3-chloro-4-hydroxyphenylamino)-4-(4-nitrophenyl)-1H-pyrrole-2,5-dione: a glycogen synthase kinase-3 inhibitor; structure in first sourceC-nitro compound;
maleimides;
monochlorobenzenes;
phenols;
secondary amino compound;
substituted aniline
antioxidant;
apoptosis inducer;
EC 2.7.11.26 (tau-protein kinase) inhibitor;
neuroprotective agent
alsterpaullonealsterpaullone : An organic heterotetracyclic compound that is 1,3-dihydro-2H-1-benzazepin-2-one which shares its 4-5 bond with the 3-2 bond of 5-nitro-1H-indole.

alsterpaullone: structure in first source
C-nitro compound;
caprolactams;
organic heterotetracyclic compound
anti-HIV-1 agent;
antineoplastic agent;
apoptosis inducer;
EC 2.7.11.1 (non-specific serine/threonine protein kinase) inhibitor;
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor;
EC 2.7.11.26 (tau-protein kinase) inhibitor
quercetin7-hydroxyflavonol;
pentahydroxyflavone
antibacterial agent;
antineoplastic agent;
antioxidant;
Aurora kinase inhibitor;
chelator;
EC 1.10.99.2 [ribosyldihydronicotinamide dehydrogenase (quinone)] inhibitor;
geroprotector;
phytoestrogen;
plant metabolite;
protein kinase inhibitor;
radical scavenger
apigeninChamomile: Common name for several daisy-like plants (MATRICARIA; TRIPLEUROSPERMUM; ANTHEMIS; CHAMAEMELUM) native to Europe and Western Asia, now naturalized in the United States and Australia.trihydroxyflavoneantineoplastic agent;
metabolite
luteolin3'-hydroxyflavonoid;
tetrahydroxyflavone
angiogenesis inhibitor;
anti-inflammatory agent;
antineoplastic agent;
apoptosis inducer;
c-Jun N-terminal kinase inhibitor;
EC 2.3.1.85 (fatty acid synthase) inhibitor;
immunomodulator;
nephroprotective agent;
plant metabolite;
radical scavenger;
vascular endothelial growth factor receptor antagonist
kaempferol7-hydroxyflavonol;
flavonols;
tetrahydroxyflavone
antibacterial agent;
geroprotector;
human blood serum metabolite;
human urinary metabolite;
human xenobiotic metabolite;
plant metabolite
harmineharmine : A harmala alkaloid in which the harman skeleton is methoxy-substituted at C-7.

Harmine: Alkaloid isolated from seeds of PEGANUM HARMALA; ZYGOPHYLLACEAE. It is identical to banisterine, or telepathine, from Banisteria caapi and is one of the active ingredients of hallucinogenic drinks made in the western Amazon region from related plants. It has no therapeutic use, but (as banisterine) was hailed as a cure for postencephalitic PARKINSON DISEASE in the 1920's.
harmala alkaloidanti-HIV agent;
EC 1.4.3.4 (monoamine oxidase) inhibitor;
metabolite
chrysinchrysin : A dihydroxyflavone in which the two hydroxy groups are located at positions 5 and 7.7-hydroxyflavonol;
dihydroxyflavone
anti-inflammatory agent;
antineoplastic agent;
antioxidant;
EC 2.7.11.18 (myosin-light-chain kinase) inhibitor;
hepatoprotective agent;
plant metabolite
fisetin3'-hydroxyflavonoid;
7-hydroxyflavonol;
tetrahydroxyflavone
anti-inflammatory agent;
antioxidant;
EC 5.99.1.3 [DNA topoisomerase (ATP-hydrolysing)] inhibitor;
geroprotector;
metabolite;
plant metabolite
alvocidibalvocidib : A synthetic dihydroxyflavone that is 5,7-dihydroxyflavone which is substituted by a 3-hydroxy-1-methylpiperidin-4-yl group at position 8 and by a chlorine at the 2' position (the (-)-3S,4R stereoisomer). A cyclin-dependent kinase 9 (CDK9) inhibitor, it has been studied for the treatment of acute myeloid leukaemia, arthritis and atherosclerotic plaque formation.

alvocidib: structure given in first source
dihydroxyflavone;
hydroxypiperidine;
monochlorobenzenes;
tertiary amino compound
antineoplastic agent;
antirheumatic drug;
apoptosis inducer;
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor
su 9516
(E)-3-(2-Hydroxyphenyl)-2-propenalcinnamaldehydes
arcyriaflavin aarcyriaflavin A: from marine ascidian, Eudistoma sp.; structure given in first sourceindolocarbazole
pd 0183812PD 0183812: inhibits CDK4 and CDK6; structure in first source
jnj-7706621sulfonamide
olomoucine iiolomoucine II: structure in first source
1-azakenpaullone1-azakenpaullone : An organic heterotetracyclic compound that is 7,12-dihydropyrido[3',2':2,3]azepino[4,5-b]indole substituted at positions 6 and 9 by oxo and bromo groups respectively.lactam;
organic heterotetracyclic compound;
organobromine compound;
organonitrogen heterocyclic compound
EC 2.7.11.26 (tau-protein kinase) inhibitor;
Wnt signalling activator
2-[(3-iodophenyl)methylthio]-5-pyridin-4-yl-1,3,4-oxadiazolearyl sulfide
b 43RK-24466 : A member of the class of pyrrolopyrimidines that is 7H-pyrrolo[2,3-d]pyrimidine substituted by amino, 4-phenoxyphenyl, and cyclopentyl groups at positions 4, 5 and 7, respectively. It is a potent inhibitor of Lck that inhibits Lck (64-509) and LckCD isoforms (IC50 of less than 1 and 2 nM, respectively).aromatic amine;
aromatic ether;
cyclopentanes;
primary amino compound;
pyrrolopyrimidine
EC 2.7.10.2 (non-specific protein-tyrosine kinase) inhibitor;
geroprotector
aminopurvalanol aaminopurvalanol A: casein kinase I alpha inhibitor; structure in first sourcemonochlorobenzenes;
purvalanol
protein kinase inhibitor
chir 99021CHIR 99021 : A member of the class of aminopyrimidines that is 2-aminopyrimidine substituted at positions N2, 5 and 6 by (5-cyanopyridin-2-yl)ethyl, 4-methylimidazol-2-yl and 2,4-dichlorophenyl groups respectively.

Chir 99021: structure in first source
aminopyridine;
aminopyrimidine;
cyanopyridine;
diamine;
dichlorobenzene;
imidazoles;
secondary amino compound
EC 2.7.11.26 (tau-protein kinase) inhibitor
meridianin ameridianin A: structure in first source
cx 4945
can 508CAN 508: has antiangiogenic activity; structure in first source

CAN-508 : A member of the class of pyrazoles that is 1H-pyrazole substituted by amino, (4-hydroxyphenyl)diazenyl, and amino groups at positions 3, 4 and 5, respectively. It is a CDK9 inhibitor (IC50 = 0.35 muM) with 38-fold selectivity for CDK9/cyclin T over other CDK/cyclin complexes.
aromatic amine;
monoazo compound;
phenols;
pyrazoles
angiogenesis inhibitor;
antineoplastic agent;
apoptosis inducer;
EC 2.7.11.22 (cyclin-dependent kinase) inhibitor
hymenialdisine