Post-meiotic Shifts in HSPA2/HSP70.2 Chaperone Activity during Mouse Spermatogenesis

Govin, Jérôme; Caron, Cécile; Escoffier, Emmanuelle; Ferro, Myriam; Kuhn, Lauriane; Rousseaux, Sophie; Eddy, Edward M.; Garin, Jérôme; Khochbin, Saadi

doi:10.1074/jbc.m608147200

Cited by 106 publications

(93 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Third, a phosphoproteome analysis of mutant testes revealed that HSPA2 (Hsp70.2) may be a target of PPP1CC (Henderson et al 2010). HSPA2 protein decorates the synaptonemal complex of pachytene spermatocytes, and is also present in a cloud of puncta over the chromatin (Govin et al 2006, Henderson et al 2010; this latter pattern is missing from Ppp1cc mutant spermatocytes, supporting the intriguing possibility that dephosphorylated HSPA2 performs a second function, different from that identified by the null mutation and related to conditioning of the germ cell chromatin in preparation for the major morphological changes the cells are about to embark upon. Furthermore, HSPA2 is highly expressed by spermatocytes and spermatids in the human testes (Son et al 1999).…”

Section: Discussionmentioning

confidence: 99%

Loss of protein phosphatase 1cγ (PPP1CC) leads to impaired spermatogenesis associated with defects in chromatin condensation and acrosome development: an ultrastructural analysis

Forgione¹,

Vogl²,

Varmuza³

2010

Reproduction

View full text Add to dashboard Cite

Human male infertility affects w5% of men, with one-third suffering from testicular failure, likely the result of an underlying genetic abnormality that disrupts spermatogenesis during development. Mouse models of male infertility such as the Ppp1cc knockout mouse display very similar phenotypes to humans with testicular failure. Male Ppp1cc mutant mice are sterile due to disruptions in spermatogenesis that begin during prepubertal testicular development, and continue into adulthood, often resulting in loss of germ cells to the point of Sertoli cell-only syndrome. The current study employs light and electron microscopy to identify new morphological abnormalities in Ppp1cc mutant seminiferous epithelium. This study reveals that germ cells become delayed in their development around stages VII and VIII of spermatogenesis. Loss of these cells likely results in the reduced numbers of elongating spermatids and spermatozoa previously observed in mutant animals. Interestingly, Ppp1cc mutants also display reduced numbers of spermatogonia compared with their wild-type counterparts. Using electron microscopy, we have shown that junction complexes in Ppp1cc mutants are ultrastructurally normal, and therefore do not contribute to the breakdown in tissue architecture seen in mutants. Electron microscopy revealed major acrosomal and chromatin condensation defects in Ppp1cc mutants. Our observations are discussed in the context of known molecular changes in Ppp1cc mutant testes.

show abstract

Section: Discussionmentioning

confidence: 99%

Loss of protein phosphatase 1cγ (PPP1CC) leads to impaired spermatogenesis associated with defects in chromatin condensation and acrosome development: an ultrastructural analysis

Forgione¹,

Vogl²,

Varmuza³

2010

Reproduction

View full text Add to dashboard Cite

show abstract

“…The testis HSP70-null male mice are infertile due to meiotic arrest in spermatocytes (17,37,39), and HSP70 may be essential in the later stages of spermatogenesis that involve SIP and SSTK. To our knowledge, SIP represents the first demonstration of a germ cell-specific cochaperone for a protein kinase that requires the HSP90 machinery for activation, and in addition to Cdc37, is only the second cochaperone identified that plays a role in protein kinase maturation.…”

Section: Discussionmentioning

confidence: 99%

Identification of a Novel HSP70-binding Cochaperone Critical to HSP90-mediated Activation of Small Serine/Threonine Kinase

Jha

Wong

Zerfas

et al. 2010

Journal of Biological Chemistry

View full text Add to dashboard Cite

We previously reported the identification of small serine/ threonine kinase (SSTK) that is expressed in postmeiotic germ cells, associates with HSP90, and is indispensable for male fertility. Sperm from SSTK-null mice cannot fertilize eggs in vitro and are incapable of fusing with eggs that lack zona pellucida. Here, using the yeast two-hybrid screen, we have discovered a novel SSTK-interacting protein (SIP) that is expressed exclusively in testis. The gene encoding SIP is restricted to mammals and encodes a 125-amino acid polypeptide with a predicted tetratricopeptide repeat domain. SIP is co-localized with SSTK in the cytoplasm of spermatids as they undergo restructuring and chromatin condensation, but unlike SSTK, is not retained in the mature sperm. SIP binds to SSTK with high affinity (K d ϳ10 nM), and the proteins associate with each other when co-expressed in cells. In vitro, SIP inhibited SSTK kinase activity, whereas the presence of SIP in cells resulted in enzymatic activation of SSTK without affecting Akt or MAPK activity. SIP was found to be associated with cellular HSP70, and analyses with purified proteins revealed that SIP directly bound HSP70. Importantly, SSTK recruited SIP onto HSP90, and treatment of cells with the specific HSP90 inhibitor, 17-allylamino-17-demethoxygeldanamycin, completely abolished SSTK catalytic activity. Hence, these findings demonstrate that HSP90 is essential for functional maturation of the kinase and identify SIP as a cochaperone that is critical to the HSP90-mediated activation of SSTK.Protein phosphorylation plays important roles during spermatogenesis (1, 2). A number of protein kinases are expressed in testis, and several of them are essential for male fertility (3). For example, disruption of the Camk4 which is involved in postmeiotic chromatin condensation, results in impaired spermiogenesis and male sterility (4). Targeted deletion of the casein kinase 2␣Ј catalytic subunit leads to oligozoospermia and extensive degeneration of germ cells at all stages of spermatogenesis (5), and Cdk2 is essential for completing mitotic division in germ cells (6). Three members of the testis-specific serine threonine kinase (TSSK) 2 family, namely TSSK1, TSSK2, and the small serine/threonine kinase (SSTK, also known as TSSK6), are expressed postmeiotically and are essential for male fertility (7-13).SSTK is one of the smallest protein kinases, consists only of N-and C-lobes of a kinase catalytic domain, and forms stable associations with heat shock protein (HSP) 70 and 90 (7). Targeted deletion of Sstk in mice resulted in male infertility without any other visible somatic defects. SSTK-null sperm could not fertilize eggs in vitro and are incapable of fusing with eggs that lack zona pellucida (9). SSTK expression first appears in elongating spermatids as they undergo cellular remodeling and chromatin condensation, and the kinase is retained in mature sperm. However, the in vivo substrate(s) for SSTK, the mechanism of activation, and the specific function that SSTK performs in spe...

show abstract

“…Our work revealed new functions for HSPA2 during post-meiotic phases, when it becomes specifically associated with transition proteins [Govin et al 2006a]. This heat shock protein appeared, therefore, as the first identified chaperone for the non-histone testis-specific DNA-packaging proteins.…”

Section: Identification and Functional Investigations Of Selected Facmentioning

confidence: 90%

“…Altogether, these data suggest that the action of Brdt on hyperacetylated chromatin is crucial for the subsequent stages of genome reorganizations which could cooperate with tH2B/H2AL2 nucleosomes to mediate histone replacement by TPs. Additionally, we could show that in elongating spermatids, these TPs are chaperoned by HSPA2 [Govin et al 2006a], a factor which has been shown to also play a critical meiotic role by mediating the desynapsis of synaptonemal complexes [Eddy 1998]. It is also tempting to propose that HSPA2 also contributes to the exchange of histones by TPs and uses its ATPase domain to facilitate nucleosome disassembly and the incorporation of TPs.…”

Section: Identification and Functional Investigations Of Selected Facmentioning

confidence: 99%

Combined proteomic andin silicoapproaches to decipher post-meiotic male genome reprogramming in mice

Rousseaux¹,

Khochbin²

2012

Systems Biology in Reproductive Medicine

Self Cite

View full text Add to dashboard Cite

During the post-meiotic maturation of the male gamete, the haploid genome undergoes major structural transitions, leading to its extreme compaction in a unique specialized structure. Although this process is highly conserved and crucial for the production of male gametes suitable for procreation, its molecular basis has remained unexplored for many years. In particular, the factors driving these events remain to be discovered. Our group has combined specific proteomic approaches with in silico analyses of available expression and sequence data in order to identify chromatin-associated factors as candidates involved in post meiotic reprogramming of the male genome of mice. Here we survey these approaches and the major results obtained. The systematic identification and the functional characterization of several of these factors has led to the proposal of the first working models, guiding us toward the understanding of this unique and very fundamental process, which has long remained one of the black boxes of modern biology.

show abstract

Post-meiotic Shifts in HSPA2/HSP70.2 Chaperone Activity during Mouse Spermatogenesis

Cited by 106 publications

References 19 publications

Loss of protein phosphatase 1cγ (PPP1CC) leads to impaired spermatogenesis associated with defects in chromatin condensation and acrosome development: an ultrastructural analysis

Loss of protein phosphatase 1cγ (PPP1CC) leads to impaired spermatogenesis associated with defects in chromatin condensation and acrosome development: an ultrastructural analysis

Identification of a Novel HSP70-binding Cochaperone Critical to HSP90-mediated Activation of Small Serine/Threonine Kinase

Combined proteomic andin silicoapproaches to decipher post-meiotic male genome reprogramming in mice

Contact Info

Product

Resources

About