Interaction of a Novel Chaperone PhLP2A With the Heat Shock Protein Hsp90

The evolutionarily conserved PhLP3 is essential for sperm development in Drosophila melanogaster

Phosducin-like proteins (PhLP) are thioredoxin domain-containing proteins that are highly conserved across unicellular and multicellular organisms. PhLP family proteins are hypothesized to function as co-chaperones in the folding of cytoskeletal proteins. Here, we present the initial molecular, biochemical, and functional characterization of CG4511 as Drosophila melanogaster PhLP3. We cloned the gene into a bacterial expression vector and produced enzymatically active recombinant PhLP3, which showed similar kinetics to previously characterized orthologues. A fly strain homozygous for a P-element insertion in the 5' UTR of the PhLP3 gene exhibited significant downregulation of PhLP3 expression. We found these male flies to be sterile. Microscopic analysis revealed altered testes morphology and impairment of spermiogenesis, leading to a lack of mature sperm. Among the most significant observations was the lack of actin cones during sperm maturation. Excision of the P-element insertion in PhLP3 restored male fertility, spermiogenesis, and seminal vesicle size. Given the high level of conservation of PhLP3, our data suggests PhLP3 may be an important regulator of sperm development across species.

PDCL3 is a prognostic biomarker associated with immune infiltration in hepatocellular carcinoma

BACKGROUND

Phosducin-like 3 (PDCL3) is a member of the photoreceptor family, characterized by a thioredoxin-like structural domain and evolutionary conservation. It plays roles in angiogenesis and apoptosis. Despite its significance, research on the biological role of PDCL3 in liver hepatocellular carcinoma (LIHC) remains limited. This study aims to explore the prognostic value and potential mechanisms of PDCL3 in cancer, particularly in LIHC, through bioinformatics analysis.

METHODS

RNA-seq data and corresponding clinical information for pan-cancer and LIHC were extracted from the TCGA database to analyze PDCL3 expression and survival prognosis. Differential expression of PDCL3 was analyzed using the HPA database. GO and KEGG enrichment analysis were performed for PDCL3-associated genes. The relationship between PDCL3 expression and various immune cell types was examined using the TIMER website. Clinical samples were collected, and immunohistochemistry and immunofluorescence experiments were conducted to validate the differential expression of PDCL3 in LIHC and normal tissues. In vitro assays, including CCK-8, wound healing, Transwell, and colony formation experiments, were employed to determine the biological functions of PDCL3 in LIHC cells.

RESULTS

Analysis from TIMER, GEPIA, UALCAN, and HPA databases revealed differential expression of PDCL3 in various tumors. Prognostic analysis from GEPIA and TCGA databases indicated that high PDCL3 expression was associated with poorer clinical staging and prognosis in LIHC. Enrichment analysis of PDCL3-associated genes revealed its involvement in various immune responses. TCGA and TIMER databases showed that high PDCL3 expression in LIHC decreased tumor immune activity by reducing macrophage infiltration. PDCL3 exhibited positive correlations with multiple immune checkpoint genes. Immunohistochemistry (IHC) and immunofluorescence (IF) experiments confirmed elevated PDCL3 expression in LIHC tissues compared to adjacent normal tissues. In vitro experiments demonstrated that PDCL3 promoted LIHC cell proliferation, migration, invasion, and colony-forming ability.

CONCLUSION

PDCL3 is highly expressed in various cancer types. Our study suggests that elevated PDCL3 expression in hepatocellular carcinoma is associated with poorer prognosis and may serve as a potential diagnostic biomarker for LIHC. PDCL3 may regulate the biological functions of LIHC by modulating immune infiltration. However, the precise regulatory mechanisms of PDCL3 in cancer warrant further investigation.

Advancing ASMS with LC-MS/MS for the discovery of novel PDCL2 ligands from DNA-encoded chemical library selections

BACKGROUND

A safe, effective, and reversible nonhormonal male contraceptive drug is greatly needed for male contraception as well as for circumventing the side effects of female hormonal contraceptives. Phosducin-like 2 (PDCL2) is a testis-specific phosphoprotein in mice and humans. We recently found that male PDCL2 knockout mice are sterile due to globozoospermia caused by impaired sperm head formation, indicating that PDCL2 is a potential target for male contraception. Herein, our study for the first time developed a biophysical assay for PDCL2 allowing us to screen a series of small molecules, to study structure-activity relationships, and to discover two PDCL2 binders with novel chemical structure.

OBJECTIVE

To identify a PDCL2 ligand for therapeutic male contraception, we performed DNA-encoded chemical library (DECL) screening and off-DNA hit validation using a unique affinity selection mass spectrometry (ASMS) biophysical profiling strategy.

MATERIALS AND METHODS

We employed the screening process of DECL, which contains billions of chemically unique DNA-barcoded compounds generated through individual sequences of reactions and different combinations of functionalized building blocks. The structures of the PDCL2 binders are proposed based on the sequencing analysis of the DNA barcode attached to each individual DECL compound. The proposed structure is synthesized through multistep reactions. To confirm and determine binding affinity between the DECL identified molecules and PDCL2, we developed an ASMS assay that incorporates liquid chromatography with tandem mass spectrometry (LC-MS/MS).

RESULTS

After a screening process of PDCL2 with DECLs containing >440 billion compounds, we identified a series of hits. The selected compounds were synthesized as off-DNA small molecules, characterized by spectroscopy data, and subjected to our ASMS/LC-MS/MS binding assay. By this assay, we discovered two novel compounds, which showed good binding affinity for PDCL2 in comparison to other molecules generated in our laboratory and which were further confirmed by a thermal shift assay.

DISCUSSION AND CONCLUSION AND RELEVANCE

With the ASMS/LC-MS/MS assay developed in this paper, we successfully discovered a PDCL2 ligand that warrants further development as a male contraceptive.

PPT1 regulation of HSP90α depalmitoylation participates in the pathogenesis of hyperandrogenism

Ovarian granulosa cells (GCs) in the follicle are the important mediator of steroidogenesis and foster oocyte maturation. Evidences suggested that the function of GCs could be regulated by S-palmitoylation. However, the role of S-palmitoylation of GCs in ovarian hyperandrogenism remains elusive. Here, we demonstrated that the protein from GCs in ovarian hyperandrogenism phenotype mouse group exhibits lower palmitoylation level compared with that in the control group. Using S-palmitoylation-enriched quantitative proteomics, we identified heat shock protein isoform α (HSP90α) with lower S-palmitoylation levels in ovarian hyperandrogenism phenotype group. Mechanistically, S-palmitoylation of HSP90α modulates the conversion of androgen to estrogens via the androgen receptor (AR) signalling pathway, and its level is regulated by PPT1. Targeting AR signaling by using dipyridamole attenuated ovarian hyperandrogenism symptoms. Our data help elucidate ovarian hyperandrogenism from perspective of protein modification and provide new evidence showing that HSP90α S-palmitoylation modification might be a potential pharmacological target for ovarian hyperandrogenism treatment.

Characterization of SPINK2, SPACA7 and PDCL2: Effect of immunization on fecundity, sperm function and testicular transcriptome

Testicular factors play a vital role in spermatogenesis. We characterized the functional role of rat Spink2, Spaca7 and Pdcl2 genes. Their primary, secondary and tertiary structure were deduced in silico. The genes of rat Spink2, Spaca7 and Pdcl2 mRNA were predominantly expressed in the testis. SPINK2, SPACA7 and PDCL2 protein expression was evident in all the cell types of testis and on spermatozoa. Ablation of each of these proteins by active immunization resulted in reduced fecundity and sperm count. Damage to the anatomical architecture of testis and epididymis was evident. In SPINK2 immunized rats, 283 genes were differentially regulated while it was 434 and 872 genes for SPACA7 and PDCL2 respectively. Genes that were differentially regulated in the testis of SPINK2 immunized rats primarily belonged to extracellular exosome formation, extracellular space and response to drugs. SPACA7 ablation affected genes related to extracellular space, oxidation-reduction processes, endoplasmic reticulum membrane and response to drugs. Differential gene expression was observed for nuclear function, protein binding and positive regulation of transcription from RNA polymerase II promoter in testis of PDCL2 immunized rats. Results of our study demonstrate the role of SPINK2, SPACA7 and PDCL2 in spermatogenesis and in important molecular processes that may dictate testicular function and other physiological responses as well.

Mutations in Hsp90 Cochaperones Result in a Wide Variety of Human Disorders

The Hsp90 molecular chaperone, along with a set of approximately 50 cochaperones, mediates the folding and activation of hundreds of cellular proteins in an ATP-dependent cycle. Cochaperones differ in how they interact with Hsp90 and their ability to modulate ATPase activity of Hsp90. Cochaperones often compete for the same binding site on Hsp90, and changes in levels of cochaperone expression that occur during neurodegeneration, cancer, or aging may result in altered Hsp90-cochaperone complexes and client activity. This review summarizes information about loss-of-function mutations of individual cochaperones and discusses the overall association of cochaperone alterations with a broad range of diseases. Cochaperone mutations result in ciliary or muscle defects, neurological development or degeneration disorders, and other disorders. In many cases, diseases were linked to defects in established cochaperone-client interactions. A better understanding of the functional consequences of defective cochaperones will provide new insights into their functions and may lead to specialized approaches to modulate Hsp90 functions and treat some of these human disorders.

Recent advances in understanding the role of proteostasis

Maintenance of a functional proteome is achieved through the mechanism of proteostasis that involves precise coordination between molecular machineries assisting a protein from its conception to demise. Although each organelle within a cell has its own set of proteostasis machinery, inter-organellar communication and cell non-autonomous signaling bring forth the multidimensional nature of the proteostasis network. Exposure to extrinsic and intrinsic stressors can challenge the proteostasis network, leading to the accumulation of aberrant proteins or a decline in the proteostasis components, as seen during aging and in several diseases. Here, we summarize recent advances in understanding the role of proteostasis and its regulation in aging and disease, including monogenetic and infectious diseases. We highlight some of the emerging as well as unresolved questions in proteostasis that need to be addressed to overcome pathologies associated with damaged proteins and to promote healthy aging.

Human Hsp90 cochaperones: perspectives on tissue-specific expression and identification of cochaperones with similar in vivo functions

The Hsp90 molecular chaperone is required for the function of hundreds of different cellular proteins. Hsp90 and a cohort of interacting proteins called cochaperones interact with clients in an ATP-dependent cycle. Cochaperone functions include targeting clients to Hsp90, regulating Hsp90 ATPase activity, and/or promoting Hsp90 conformational changes as it progresses through the cycle. Over the last 20 years, the list of cochaperones identified in human cells has grown from the initial six identified in complex with steroid hormone receptors and protein kinases to about fifty different cochaperones found in Hsp90-client complexes. These cochaperones may be placed into three groups based on shared Hsp90 interaction domains. Available evidence indicates that cochaperones vary in client specificity, abundance, and tissue distribution. Many of the cochaperones have critical roles in regulation of cancer and neurodegeneration. A more limited set of cochaperones have cellular functions that may be limited to tissues such as muscle and testis. It is likely that a small set of cochaperones are part of the core Hsp90 machinery required for the folding of a wide range of clients. The presence of more selective cochaperones may allow greater control of Hsp90 activities across different tissues or during development.

AT-533, a novel Hsp90 inhibitor, inhibits breast cancer growth and HIF-1α/VEGF/VEGFR-2-mediated angiogenesis in vitro and in vivo

The inhibition of angiogenesis is suggested to be an attractive strategy for cancer therapeutics. Heat shock protein 90 (Hsp90) is closely related to tumorigenesis as it regulates the stabilization and activated states of many client proteins that are essential for cell survival and tumor growth. Here, we investigated the mechanism whereby AT-533, a novel Hsp90 inhibitor, inhibits breast cancer growth and tumor angiogenesis. Based on our results, AT-533 suppressed the tube formation, cell migration, and invasion of human umbilical vein endothelial cells (HUVECs), and was more effective than the Hsp90 inhibitor, 17-AAG. Furthermore, AT-533 inhibited angiogenesis in the aortic ring, Matrigel plug, and chorioallantoic membrane (CAM) models. Mechanically, AT-533 inhibited the activation of VEGFR-2 and the downstream pathways, including Akt/mTOR/p70S6K, Erk1/2 and FAK, in HUVECs, and the viability of breast cancer cells and the HIF-1α/VEGF signaling pathway under hypoxia. In vivo, AT-533 also inhibited tumor growth and angiogenesis by inducing apoptosis and the HIF-1α/VEGF signaling pathway in breast cancer cells. Taken together, our findings indicate that the Hsp90 inhibitor, AT-533, suppresses breast cancer growth and angiogenesis by blocking the HIF-1α/VEGF/VEGFR-2 signaling pathway. AT-533 may thus be a potentially useful drug candidate for breast cancer therapy.

Effects of ginsenoside Rb1 on oxidative stress injury in rat spinal cords by regulating the eNOS/Nrf2/HO-1 signaling pathway

The present study aimed to investigate whether ginsenoside Rb1 (G-Rb1) attenuates spinal cord injury-associated oxidative stress in rats by regulating the endothelial nitric oxide synthase eNOS/nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase (HO)-1 signaling pathway. Sprague Dawley rats were randomly divided into the sham operation group (S group), spinal cord injury group (SCI group), G-Rb1 treatment group (G-Rb1 group) and SCI+G-Rb1+Inhibitor L-name group (L-name group). The posterior limb function was evaluated via the Basso, Beattie and Bresnahan scoring method. The levels of superoxide dismutase (SOD), malondialdehyde (MDA), catalase (CAT) and glutathione (GSH) in serum were measured by ELISA. The pathological changes in the spinal cord were observed by H&E staining. Reverse transcription-quantitative polymerase chain reaction and western blot analyses were used to detect eNOS, phosphorylated (p)-eNOS, heat shock protein (HSP)90, Nrf2 and NAD(P)H quinone dehydrogenase 1 (Nqo1) at the mRNA and protein level. Immunohistochemistry was used to detect the expression of Nrf2 and p-eNOS. Compared with the S group, the scores of spinal cord function in the SCI group were significantly lower, and the levels of MDA were significantly increased, while the levels of SOD, CAT and GSH protein in spinal cord were significantly decreased (P<0.05). The spinal cord tissue exhibited hemorrhage, neuronal degeneration/necrosis, as well as mononuclear cell and lymphocyte infiltration. The eNOS, HSP90, Nrf2, Nqo1 and HO-1 mRNA levels were decreased (P<0.05). Compared with those in the SCI group, the spinal cord function score in the G-Rb1 group were significantly higher and the serum MDA content was significantly decreased, while the activity of SOD, CAT and GSH was significantly increased (P<0.05). The degeneration/necrosis of spinal cord neurons was attenuated, inflammatory cell infiltration was significantly reduced and the levels of eNOS, HSP90, Nrf2, Nqo1 and HO-1 were significantly upregulated (P<0.05). In the group that was administered the eNOS inhibitor L-name, the levels of eNOS, HSP90, Nrf2, Nqo1 and HO-1 were significantly decreased. In conclusion, G-Rb1 attenuates oxidative stress in injured spinal cords. The mechanism may at least in part involve the eNOS/Nrf2/HO-1 pathway.

CacyBP/SIP, a Hsp90 binding chaperone, in cellular stress response

CacyBP/SIP interacts with Hsp90 and is able to protect proteins from denaturation and/or aggregation induced by elevated temperature. In this work we studied the influence of different stress factors on CacyBP/SIP level in HEp-2 cells. We have found that H₂O₂ and radicicol treatment resulted in a significant increase (up to 40%) in the CacyBP/SIP level. We have also found that HEp-2 cells overexpressing CacyBP/SIP were more resistant to stress-induced death. Further studies have revealed that the Hsf1 transcription factor binds to the CacyBP/SIP gene promoter and up-regulates CacyBP/SIP expression under stress conditions. To check whether the CacyBP/SIP protein might play a role in stress responses in vivo, we analyzed its level in selected brain structures of control and stressed mice. We have found that the level of the CacyBP/SIP protein was higher in the thalamus/hypothalamus, hippocampus and brainstem of stressed mice. Thus, the presented results clearly indicate that CacyBP/SIP is involved in cellular stress response.

Genome-wide scan for runs of homozygosity identifies potential candidate genes associated with local adaptation in Valle del Belice sheep

Background

Because very large numbers of single nucleotide polymorphisms (SNPs) are now available throughout the genome, they are particularly suitable for the detection of genomic regions where a reduction in heterozygosity has occurred and they offer new opportunities to improve the accuracy of inbreeding (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$F$$\end{document}F) estimates. Runs of homozygosity (ROH) are contiguous lengths of homozygous segments of the genome where the two haplotypes inherited from the parents are identical. Here, we investigated the occurrence and distribution of ROH using a medium-dense SNP panel to characterize autozygosity in 516 Valle del Belice sheep and to identify the genomic regions with high ROH frequencies.

Results

We identified 11,629 ROH and all individuals displayed at least one ROH longer than 1 Mb. The mean value of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$F$$\end{document}F estimated from ROH longer than1 Mb was 0.084 ± 0.061. ROH that were shorter than 10 Mb predominated. The highest and lowest coverages of Ovis aries chromosomes (OAR) by ROH were on OAR24 and OAR1, respectively. The number of ROH per chromosome length displayed a specific pattern, with higher values for the first three chromosomes. Both number of ROH and length of the genome covered by ROH varied considerably between animals. Two hundred and thirty-nine SNPs were considered as candidate markers that may be under directional selection and we identified 107 potential candidate genes. Six genomic regions located on six chromosomes, corresponding to ROH islands, are presented as hotspots of autozygosity, which frequently coincided with regions of medium recombination rate. According to the KEGG database, most of these genes were involved in multiple signaling and signal transduction pathways in a wide variety of cellular and biochemical processes. A genome scan revealed the presence of ROH islands in genomic regions that harbor candidate genes for selection in response to environmental stress and which underlie local adaptation.

Conclusions

These results suggest that natural selection has, at least partially, a role in shaping the genome of Valle del Belice sheep and that ROH in the ovine genome may help to detect genomic regions involved in the determinism of traits under selection.

Electronic supplementary material

The online version of this article (10.1186/s12711-017-0360-z) contains supplementary material, which is available to authorized users.