Sea urchin testicular cells evaluated by fluorescence microscopy of unfixed tissue

Simpson, Marcia V.; Poccia, Dominic

doi:10.1002/mrd.1120170205

Cited by 12 publications

(1 citation statement)

References 11 publications

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“…On the basis of in vivo labeling experiments with our polyspermic system and many studies on gametogenesis and mitosis progression that suggested that histone phosphorylation/dephosphorylation events accompany gross changes in chromatin condensation (Green and Poccia, 1985;Simpson and Poccia, 1987;Green and Poccia, 1988;Roberge Th'ng et al, 1990;Oliva and Dixon, 1991;Green et al, 1993;Green et al, 1994), we postulated that phos-phorylation of the sperm-specific histones SpH1 and SpH2B would be required to alter the affinities of their highly basic N-terminal extensions (and the Sp H1 C-terminal extension) with the negatively charged backbone of chromatin linker DNA to permit postfertilization chromatin decondensation (Green and Poccia, 1988).…”

Section: Phosphorylation Of Sperm-specific Histones and Sperm Lamin Bmentioning

confidence: 99%

A sea urchin cell-free system to study male pronuclear assembly and activation

Poccia

2016

Int. J. Dev. Biol.

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Typically sperm nuclei are genetically inert and contain extremely compacted chromatin. Following fertilization, the first steps in their conversion to somatic nuclei (male pronuclei) which will support further development involve chromatin decondensation and the formation of a new nuclear envelope. We have studied the reactivation of sea urchin sperm nuclei in a cell-free system derived from homogenates of activated sea urchin egg cytoplasm. The cell-free system has provided several novel insights including requirements for sperm-specific histone phosphorylation on N- and C-terminal extensions and disassembly of the sperm nuclear lamina for decondensation, the utilization of remnant regions of the sperm nuclear envelope to direct polarized binding and fusion of egg membranes to form the new nuclear envelope, and a role for phosphoinositide metabolism in initiation of membrane fusion through binding of a minor membrane fraction enriched in PtdIns (4,5)P, PLCγ and SFK1 which locally produces a fusigenic lipid, diacylglycerol.

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Section: Phosphorylation Of Sperm-specific Histones and Sperm Lamin Bmentioning

confidence: 99%

A sea urchin cell-free system to study male pronuclear assembly and activation

Poccia

2016

Int. J. Dev. Biol.

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Phosphorylation at clustered -Ser-Pro-X-Lys/Arg- motifs in sperm-specific histones H1 and H2B.

1990

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Sea urchin sperm‐specific histones H1 and H2B have distinctive N‐terminal, and in the case of H1 also C‐terminal, domains containing repeats of a basic motif (‐Ser‐Pro‐Lys/Arg‐Lys/Arg‐ or a closely related sequence). The histones in spermatids (the precursors of sperm) are phosphorylated, and the unphosphorylated histones of mature sperm are rephosphorylated upon fertilization. These changes correlate with finely tuned changes in chromatin packing in the nucleus, and the domains responsible are evidently the N‐terminal domains. We show that in spermatids there are six tandemly repeated phosphorylation sites in the N‐terminal domain of H1 (a typical cAMP dependent protein kinase site is not phosphorylated) and that H2B is phosphorylated in the N‐terminal domain at two or three sites in the case of H2B1 and four sites in H2B2. The consensus sequence for phosphorylation is ‐Ser‐Pro‐X‐Lys/Arg‐, where X is Thr, Gln, Lys or Arg. There is an additional phosphorylated site in the C‐terminal domain of H1 but most (or possibly all) copies of the consensus motif, which are here dispersed, are not phosphorylated. The negative charge introduced upon phosphorylation would be expected to weaken or abolish electrostatic interaction with DNA of this motif, which also occurs, and is phosphorylated, in somatic H1s.

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Histone-DNA interactions and their modulation by phosphorylation of -Ser-Pro-X-Lys/Arg- motifs.

et al. 1991

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The sea urchin sperm‐specific histones H1 and H2B are multiply phosphorylated in spermatids, dephosphorylated in the final stages of spermatogenesis to give mature sperm, and rephosphorylated upon fertilization. Phosphorylation in spermatids, and probably at fertilization, occurs at repeated ‐Ser‐Pro‐X‐Basic‐motifs in the distinctive N‐terminal basic domains of both histones and at the end of the much longer C‐terminal domain of H1. Here we identify the consequences of multiple phosphorylation through comparison of some physical and biochemical properties of spermatid (phosphorylated) and sperm (dephosphorylated) chromatin and histones. Study of the DNA binding properties of the intact histones and isolated basic domains suggests that phosphorylation at three dispersed sites in the C‐terminal tail of H1 has little effect on its overall DNA binding affinity, whereas, strikingly, binding of the N‐terminal domains of H2B and H1 is abolished by phosphorylation at four or six tandemly repeated sites respectively. Together with the relative timing of events in vivo, this suggests that phosphorylation/dephosphorylation of the N‐terminal (and distal end of the C‐terminal) tail of H1, and/or the N‐terminal tail of H2B, effectively controls intermolecular interactions between adjacent chromatin filaments, and hence chromatin packing in the sperm nucleus.

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Sea urchin testicular cells evaluated by fluorescence microscopy of unfixed tissue

Cited by 12 publications

References 11 publications

A sea urchin cell-free system to study male pronuclear assembly and activation

A sea urchin cell-free system to study male pronuclear assembly and activation

Phosphorylation at clustered -Ser-Pro-X-Lys/Arg- motifs in sperm-specific histones H1 and H2B.

Histone-DNA interactions and their modulation by phosphorylation of -Ser-Pro-X-Lys/Arg- motifs.

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