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Principal Investigator: Saher Sue Hammoud
Organization: WAYNE STATE UNIVERSITY
Fiscal Year: 2024
Award: $658,633
Funding agency: Eunice Kennedy Shriver National Institute of Child Health and Human Development
Natural fertilization and embryo development require heathy spermatozoa to carry male genetic material to
fertilize the egg. During the final phase of spermatogenesis, the spermatids undergo dramatic changes including
the formation of the flagella, condensation of chromatin and so on. A spermatid-specific structure, the manchette,
is believed to play an essential role during spermiogenesis. Two functions for the manchette have been proposed:
1) transporting cargo proteins by intra-manchette transport (IMT) for sperm flagella assembly and 2) remodeling
chromatin by replacing histones with germ cell-specific nuclear proteins. However, little is known about how
protein complexes are assembled and transported in the manchette, or the manchette contributes to chromatin
remodeling; and the IMT process has never been observed. The long-term objective of this research is to explore
the mechanisms of meiosis-expressed gene 1 (MEIG1) complex in IMT for sperm flagella formation and in
remodeling the chromatin for normal embryogenesis. The proposed studies are based our findings that MEIG1
plays an indispensable role in normal sperm flagella formation and chromatin remodeling. MEIG1 is present in
the whole cell bodies in the spermatocytes and rounds spermatids, but it is recruited to the manchette by Parkin
co-regulated gene (PACRG). MEIG1/PACRG localization in the manchette is dependent on a PACRG binding
partner, the axonemal dynein light intermediate chain 1 (DNALI1). DNALI1 is a binding partner of cytoplasmic
dynein heavy chain 1 (DHC1), which directly binds to microtubules for cargo transport. Both DNALI1 and DHC1
are localized to the manchette independent of PACRG and MEIG1. More recently, intracytoplasmic sperm
injection (ICSI) using sperm from the PACRG mutant mice and a Meig1 KO mouse revealed failure of normal
embryogenesis, indicating a functional defect of sperm chromatin in these KO/mutant mice. Based on these
observations, we propose that MEIG1 complex plays important roles in transporting cargos through IMT for
sperm tail formation and in the formation of male-germ cell specific chromatin essential for normal
embryogenesis. To test these hypotheses, we propose the following studies.1: To dissect a motor-based
complex in the manchette and study its role in sperm formation; 2: To establish an in vivo system to investigate
the protein traffic through IMT; and 3: To examine the contribution and mechanisms of the MEIG1 complex for
remodeling nuclear chromatin during spermiogenesis. We expect that DNALI1/DHC1 motors form a cargo
transport system with MEIG1 complex in elongating spermatids for normal sperm formation; the dynamic traffic
process of IMT can be visualized in live germ cells using knock-in mouse models to express fluorescence-tagged
proteins; and MEIG1 complex plays an essential role in for chromatin remodeling by replacing histones with male
germ cell-specific nuclear proteins. The proposed studies will dissect the macromolecular complexes in the
manchette that are essential for spermiogenesis and establish an in vivo system to study IMT. The proposed
studies will also reveal a novel mechanism in chromatin remodeling for normal embryogenesis.
Terms: <Amino Acids><Antigens><Binding><Cell Body><Cell Nucleus><Cells><Chromatin><Chromatin Structure><Chromosome Mapping><Comet Assay><Complex><Cytoplasm><DNA Damage><DNA Injury><Defect><Dynein><Dynein ATPase><Dynein Adenosine Triphosphatase><Dynein Adenosinetriphosphatase><Embryo Development><Embryogenesis><Embryonic Development><Failure><Fertilization><Fertilized Egg><Fertilized Ovum><Flagella><Fluorescence><Gametes><Gene Localization><Gene Mapping><Gene Mapping Genetics><Genes><Genetic Alteration><Genetic Change><Genetic Materials><Genetic defect><Genome><Germ Cells><Germ-Line Cells><Histones><ICSI><Injections><Intracytoplasmic Sperm Injections><KI mice><KO mice><Knock-in Mouse><Knock-out><Knock-out Mice><Knockout><Knockout Mice><Light><Linkage Mapping><M Phase><Macromolecular Complexes><Male Contraception><Male Contraceptive Agents><Male Contraceptives><Male Infertility><Mediating><Meiosis><Mice><Mice Mammals><Micro-tubule><Microtubules><Mitosis><Mitosis Stage><Modeling><Molecular><Molecular Interaction><Molecular Transport><Motor><Murine><Mus><Mutant Strains Mice><Mutation><Nuclear><Nuclear Proteins><Nucleus><Null Mouse><Parkin><Parkin gene><Pattern><Phase><Phenotype><Photoradiation><Physical condensation><Play><Probability><Process><Protein Trafficking><Proteins><Proteomics><Reproductive Cells><Research><Role><Sex Cell><Single-Cell Gel Electrophoresis><Sperm><Sperm Flagellum><Sperm Head><Sperm Tail><Sperm Transport><Spermatids><Spermatoblasts><Spermatocytes><Spermatogenesis><Spermatozoa><Spermiocytes><Spermiogenesis><Structure><System><Testing><Time><Total Human and Non-Human Gene Mapping><Transport Process><Visualization><aminoacid><chromatin remodeling><comparative><condensation><contraceptive target><driving force><fertilizations><gene interaction><genetic mapping><genome mutation><immunogen><in vivo><initial cell><knockin mice><male><male antifertility drug><male germ cells><meiotic><mouse model><mouse mutant><murine model><mutant mouse model><novel><parkin protein><protein complex><protein transport><recruit><sexual cell><social role><sperm cell><spermatozoon head><spermatozoon tail><spermid><spermoblast><zoosperm><zygote>