Article

Tyrosine phosphoproteome of hamster spermatozoa: role of glycerol-3-phosphate dehydrogenase 2 in sperm capacitation.

Centre for Cellular and Molecular Biology, Hyderabad, Andhra Pradesh, India.
Proteomics (impact factor: 4.43). 05/2009; 9(7):1809-26. DOI:10.1002/pmic.200800519 pp.1809-26
Source: PubMed

ABSTRACT Capacitation confers on the spermatozoa the competence to fertilize the oocyte. At the molecular level, a cyclic adenosine monophosphate (cAMP) dependent protein tyrosine phosphorylation pathway operates in capacitated spermatozoa, thus resulting in tyrosine phosphorylation of specific proteins. Identification of these tyrosine-phosphorylated proteins and their function with respect to hyperactivation and acrosome reaction, would unravel the molecular basis of capacitation. With this in view, 21 phosphotyrosine proteins have been identified in capacitated hamster spermatozoa out of which 11 did not identify with any known sperm protein. So, in the present study attempts have been made to ascertain the role of one of these eleven proteins namely glycerol-3-phosphate dehydrogenase 2 (GPD2) in hamster sperm capacitation. GPD2 is phosphorylated only in capacitated hamster spermatozoa and is noncanonically localized in the acrosome and principal piece in human, mouse, rat, and hamster spermatozoa, though in somatic cells it is localized in the mitochondria. This noncanonical localization may imply a role of GPD2 in acrosome reaction and hyperactivation. Further, enzymatic activity of GPD2 during capacitation correlates positively with hyperactivation and acrosome reaction thus demonstrating that GPD2 may be required for sperm capacitation.

0 0
 · 
0 Bookmarks
 · 
24 Views
  • Source
    Article: Functional cooperation between CREM and GCNF directs gene expression in haploid male germ cells.
    Mirjana Rajkovic, K Alexander H Iwen, Peter J Hofmann, Angelika Harneit, Joachim M Weitzel
    [show abstract] [hide abstract]
    ABSTRACT: Cellular differentiation and development of germ cells critically depend on a coordinated activation and repression of specific genes. The underlying regulation mechanisms, however, still lack a lot of understanding. Here, we describe that both the testis-specific transcriptional activator CREMtau (cAMP response element modulator tau) and the repressor GCNF (germ cell nuclear factor) have an overlapping binding site which alone is sufficient to direct cell type-specific expression in vivo in a heterologous promoter context. Expression of the transgene driven by the CREM/GCNF site is detectable in spermatids, but not in any somatic tissue or at any other stages during germ cell differentiation. CREMtau acts as an activator of gene transcription whereas GCNF suppresses this activity. Both factors compete for binding to the same DNA response element. Effective binding of CREM and GCNF highly depends on composition and epigenetic modification of the binding site. We also discovered that CREM and GCNF bind to each other via their DNA binding domains, indicating a complex interaction between the two factors. There are several testis-specific target genes that are regulated by CREM and GCNF in a reciprocal manner, showing a similar activation pattern as during spermatogenesis. Our data indicate that a single common binding site for CREM and GCNF is sufficient to specifically direct gene transcription in a tissue-, cell type- and differentiation-specific manner.
    Nucleic Acids Research 04/2010; 38(7):2268-78. · 8.03 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

21 phosphotyrosine proteins
 
acrosome reaction
 
capacitated hamster spermatozoa
 
capacitated spermatozoa
 
capacitation correlates
 
cyclic adenosine monophosphate
 
eleven proteins
 
hamster sperm capacitation
 
hamster spermatozoa
 
molecular basis
 
molecular level
 
noncanonical localization
 
noncanonically localized
 
principal piece
 
somatic cells
 
specific proteins
 
sperm capacitation
 
sperm protein
 
tyrosine phosphorylation
 
tyrosine-phosphorylated proteins
 

Venkatesh Kota