Male germ cells contain a large number of isoprotein variants for common enzymes and structural proteins. The long term objective of this study is to understand the biological importance of isozyme/isoprotein substitutions in the mammalian testis and the mechanisms that regulate spermatogenesis. Specifically, efforts will focus on the mechanisms regulating the coordinate up-regulation and down-regulation of the cytochromes c in the mammalian testis.
In specific aim 1, mice lacking the testis/male germ cell-specific cytochrome cT isoprotein will be produced by gene targeting to determine whether cytochrome cT is essential for spermatogenesis and examine the mechanism of cross-talk between the two testicular cytochromes c genes in the cytochrome cT deficient mice.
In specific aim 2, in vitro analyses of the putative cis-acting DNA elements and the transacting protein factors that bind to these putative elements to regulate the somatic cell-type, cytochrome cs, and the male germ cell-type, cytochrome cT, expression will be conducted.
In specific aim 3, the mechanism(s) by which the 5' untranslated regions of the cytochrome cT mRNAs modulate translation of the isoprotein will be studied. The experiments described in this proposal will attempt to determine the mechanisms whereby a ubiquitous mitochondrial protein is replaced at a specific stage of male germ cell differentiation by a testis specific protein variant and whether this coordinate regulation of gene expression is a prerequisite for normal spermatogenesis and maintenance of fertility. In addition, these studies may elucidate a mechanism of general interest for the coordinate down-regulation and up-regulation of specific genes in highly differentiated mammalian cells.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD011878-21
Application #
2673436
Study Section
Special Emphasis Panel (ZRG2-REN (02))
Project Start
1979-09-30
Project End
2002-05-31
Budget Start
1998-06-01
Budget End
1999-05-31
Support Year
21
Fiscal Year
1998
Total Cost
Indirect Cost
Name
University of Pennsylvania
Department
Obstetrics & Gynecology
Type
Schools of Medicine
DUNS #
042250712
City
Philadelphia
State
PA
Country
United States
Zip Code
19104
Syed, V; Hecht, N B (2002) Disruption of germ cell-Sertoli cell interactions leads to spermatogenic defects. Mol Cell Endocrinol 186:155-7
Syed, V; Hecht, N B (2001) Selective loss of Sertoli cell and germ cell function leads to a disruption in sertoli cell-germ cell communication during aging in the Brown Norway rat. Biol Reprod 64:107-12
Chennathukuzhi, V M; Lefrancois, S; Morales, C R et al. (2001) Elevated levels of the polyadenylation factor CstF 64 enhance formation of the 1kB Testis brain RNA-binding protein (TB-RBP) mRNA in male germ cells. Mol Reprod Dev 58:460-9
Syed, V; Gomez, E; Hecht, N B (1999) mRNAs encoding a von Ebner's-like protein and the Huntington disease protein are induced in rat male germ cells by Sertoli cells. J Biol Chem 274:10737-42
Syed, V; Gomez, E; Hecht, N B (1999) Messenger ribonucleic acids encoding a serotonin receptor and a novel gene are induced in Sertoli cells by a secreted factor(s) from male rat meiotic germ cells. Endocrinology 140:5754-60
Syed, V; Hecht, N B (1998) Rat pachytene spermatocytes down-regulate a polo-like kinase and up-regulate a thiol-specific antioxidant protein, whereas sertoli cells down-regulate a phosphodiesterase and up-regulate an oxidative stress protein after exposure to methoxyethanol and met Endocrinology 139:3503-11
Gu, W; Hecht, N B (1997) The enzymatic activity of Cu/Zn superoxide dismutase does not fluctuate in mouse spermatogenic cells despite mRNA changes. Exp Cell Res 232:371-5
Yiu, G K; Murray, M T; Hecht, N B (1997) Deoxyribonucleic acid-protein interactions associated with transcriptional initiation of the mouse testis-specific cytochrome c gene. Biol Reprod 56:1439-49
Yiu, G K; Hecht, N B (1997) Novel testis-specific protein-DNA interactions activate transcription of the mouse protamine 2 gene during spermatogenesis. J Biol Chem 272:26926-33
Choi, Y C; Aizawa, A; Hecht, N B (1997) Genomic analysis of the mouse protamine 1, protamine 2, and transition protein 2 gene cluster reveals hypermethylation in expressing cells. Mamm Genome 8:317-23

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