Loss of Lamin A leads to the nuclear translocation of AGO2 and compromised RNA interference.

In mammals, RNA interference (RNAi) was historically studied as a cytoplasmic event; however, in the last decade, a growing number of reports convincingly show the nuclear localization of the Argonaute (AGO) proteins. Nevertheless, the extent of nuclear RNAi and its implication in biological mechanisms remain to be elucidated. We found that reduced Lamin A levels significantly induce nuclear influx of AGO2 in SHSY5Y neuroblastoma and A375 melanoma cancer cell lines, which normally have no nuclear AGO2. Lamin A KO manifested a more pronounced effect in SHSY5Y cells compared to A375 cells, evident by changes in cell morphology, increased cell proliferation, and oncogenic miRNA expression. Moreover, AGO fPAR-CLIP in Lamin A KO SHSY5Y cells revealed significantly reduced RNAi activity. Further exploration of the nuclear AGO interactome by mass spectrometry identified FAM120A, an RNA-binding protein and known interactor of AGO2. Subsequent FAM120A fPAR-CLIP, revealed that FAM120A co-binds AGO targets and that this competition reduces the RNAi activity. Therefore, loss of Lamin A triggers nuclear AGO2 translocation, FAM120A mediated RNAi impairment, and upregulation of oncogenic miRNAs, facilitating cancer cell proliferation.

GTPBP8 plays a role in mitoribosome formation in human mitochondria.

Mitochondrial gene expression relies on mitoribosomes to translate mitochondrial mRNAs. The biogenesis of mitoribosomes is an intricate process involving multiple assembly factors. Among these factors, GTP-binding proteins (GTPBPs) play important roles. In bacterial systems, numerous GTPBPs are required for ribosome subunit maturation, with EngB being a GTPBP involved in the ribosomal large subunit assembly. In this study, we focus on exploring the function of GTPBP8, the human homolog of EngB. We find that ablation of GTPBP8 leads to the inhibition of mitochondrial translation, resulting in significant impairment of oxidative phosphorylation. Structural analysis of mitoribosomes from GTPBP8 knock-out cells shows the accumulation of mitoribosomal large subunit assembly intermediates that are incapable of forming functional monosomes. Furthermore, fPAR-CLIP analysis reveals that GTPBP8 is an RNA-binding protein that interacts specifically with the mitochondrial ribosome large subunit 16 S rRNA. Our study highlights the role of GTPBP8 as a component of the mitochondrial gene expression machinery involved in mitochondrial large subunit maturation.

Integrative transcriptomic and proteomic profiling of the effects of cell confluency on gene expression.

In this study we examine the impact of cell confluency on gene expression. We focused on Argonaute (AGO) protein dynamics and associated gene and protein expression in HEK293, A375, and SHSY5Y cell lines. As a consequence of cell confluency, AGO2 protein translocates into the nucleus. Therefore, we generated transcriptomic data using RNA sequencing to compare gene expression in subconfluent versus confluent cells, which highlighted significant alterations in gene regulation patterns directly corresponding to changes in cell density. Our study also encompasses miRNA profiling data obtained through small RNA sequencing, revealing miRNA expressional changes dependent on cellular confluency, as well as cellular localization. Finally, we derived proteomic data from mass spectrometry analyses following AGO1-4 immunoprecipitation, providing a comprehensive view of AGO interactome in both nuclear and cytoplasmic compartments under varying confluency. These datasets offer a detailed exploration of the cellular and molecular dynamics, influenced by cell confluency, presenting a valuable resource for further research in cellular biology, particularly in understanding the basic mechanisms of cell density in cancer cells.

Membrane-bound Glucose regulated protein 78 interacts with alpha-2-macroglobulin to promote actin reorganization in sperm during epididymal maturation.

Glucose regulated protein 78 (GRP78) is expressed on cell surface in exceptional conditions as seen in cancer cells and macrophages. We have reported its membrane localization in sperm. The functional significance of its surface localization in sperm is an enigma. Alpha-2-macroglobulin (α2M) reportedly binds surface GRP78, regulating macrophage motility. Additionally, seminal plasma α2M levels are low in cases of asthenozoospermia. We investigated the functional relevance of sperm surface GRP78 and α2M crosstalk using testicular sperm (Tsp; immature) and caudal sperm (Cdsp; mature) from adult Holtzman rats. α2M colocalized and interacted with GRP78 and was significantly higher in Cdsp. Cofilin pathway proteins were detected in Tsp and Cdsp, however the pathway was highly active in Cdsp. Tsp surface GRP78 tyrosine phosphorylation and [Ca2+]i levels increased significantly on exposure to activated α2M (α2M*). This binding activated Rac/Cdc42, and consequently PAK, leading to LIMK and cofilin phosphorylation and thus promoting actin reorganization. Cofilin translocation from the sperm tail to the head in the presence of α2M* possibly prevented F-actin depolymerization in the tail. Thus, profiles observed with Cdsp could be re-created upon exposure of Tsp with α2M*. We conclude that α2M secreted into seminiferous tubule fluid by Sertoli cells, may be activated by proteinases in the epididymis and may bind to sperm surface GRP78 during epididymal transit, thereby facilitating sperm motility via actin reorganization. As F-actin is required for maintaining structural integrity and hyperactivated motility in sperm, our finding has significant implications in light of our previous reports of reduced GRP78 phosphorylation and the actin-based motility pathway being significantly altered in asthenozoospermia.

Glucose Regulated Protein 78 Phosphorylation in Sperm Undergoes Dynamic Changes during Maturation.

GRP78, a resident endoplasmic reticulum (ER) chaperone involved in protein transport, folding and assembly, has been reported in sperm. It is shown to be localized in the neck region of human sperm. We have previously reported GRP78 to be less phosphorylated in asthenozoosperm.The present study aimed to determine whether sperm GRP78 undergoes phosphorylation changes during epididymal maturation and whether there are any differences in GRP78 phosphoforms in asthenozoosperm vis-à-vis normozoosperm. Testicular- and cauda epididymal- sperm from adult male Holtzman rats, and semen ejaculates collected from normal and asthenozoospermic individuals were investigated. DIGE carried out to determine phosphorylation of GRP78 in asthenozoosperm and normal sperm reveals a shift in the location of GRP78 of asthenozoosperm towards the alkaline pH, indicative of reduced GRP78 phosphorylation. Immunoprecipitation studies using antibodies specific to GRP78, serine-, threonine-, and tyrosine phosphorylation and Pan phospho antibody demonstrates GRP78 to be phosphorylated at all three residues in rat spermatozoa. Phosphatase assays using Calf intestinal alkaline phosphatase and Lambda protein phosphatase followed by nanofluidic proteomic immunoassay (NIA) show that in rat, GP4.96, GP4.94 and GP4.85 are the three phosphoforms in mature (caudal) sperm as against two phosphoforms GP4.96and GP4.94in immature (testicular) sperm. In mature human sperm GP5.04, GP4.96, and GP4.94were the 3 phosphoforms observed. GP4.94[P = 0.014]andGP5.04 [P = 0.02] are significantly reduced in asthenozoosperm. Ours is the first report indicating GRP78 in sperm to be phosphorylated at serine, threonine and tyrosine residues contrary to published literature reporting GRP78 not to be tyrosine phosphorylated. We report the presence of GRP78 phosphoforms in rat- and human- sperm and our data suggest that GRP78 phosphorylation in sperm undergoes spatial reorganization during epididymal maturation. Significant differences observed in 2 out of 3 phosphoforms in asthenozoosperm suggest that GRP78 phosphorylation may have functional relevance in sperm with consequent clinical implications.

Erratum to: A novel ELISA for diagnosis of Glanzmann's thrombasthenia and the heterozygote carriers.

Erratum to: Annals of Hematology 91(6): 917­921. DOI 10.1007/s00277-011-1390-1 . The authors inadvertently omitted 2 fellow authors from the author list: Dr. Diego Butera should be listed as the fourth author. His affiliation is Lowy Cancer Research Centre and Prince of Wales Clinical School, University of New South Wales, Sydney, NSW, Australia. His contributions are as follows: Designed, synthesized and produced EcAPv. He has no competing interests to declare. Dr. Geraldo S. Magalhaes should be listed as the fifth author. His affiliation is Laboratory of Immunopathology, Butantan Institute, São Paulo, SP, Brazil. His contributions are as follows: Produced more EcAPv when requested in October 2009. He has no competing interests to declare.

Sperm phosphoproteome profiling by ultra performance liquid chromatography followed by data independent analysis (LC-MS(E)) reveals altered proteomic signatures in asthenozoospermia.

Sperm motility is an important prerequisite for successful fertilization and is regulated by cyclic AMP activated protein kinase A which phosphorylates flagella proteins like axonemal dynein and initiates motility. Increase in calcium influx reverses this process by dephosphorylation that is mediated by calcineurin. Analyzing the phosphoenriched fractions of spermatozoa lysates from eight normozoospermic-, and asthenozoospermic-samples, respectively, by Nano UPLC-MS(E), the present study investigates the phosphoproteins involved in sperm motility in an attempt to identify the key pathways regulating sperm motility and likely to be altered in spermatozoa of asthenozoospermic individuals. 66 phosphoproteins were differentially regulated in asthenozoospermia. The deregulated proteins comprised predominantly the HSPs, cytoskeletal proteins, proteins associated with the fibrous sheath, and those associated with energy metabolism. EM analysis of these spermatozoa demonstrated significant defects in mitochondria, and fibrous sheath and these defects could be correlated with the altered proteome. Pathway analysis revealed that carbohydrate and energy metabolism, cAMP mediated PKA signaling, PI3K/AKT signaling and pathway regulating actin based motility by Rho were significantly altered indicating that motility in spermatozoa is regulated through the concerted effort of these pathways. The data identified signature molecules that have the potential as biomarkers for diagnosing etiology of asthenozoospermia.

A novel ELISA for diagnosis of Glanzmann's thrombasthenia and the heterozygote carriers.

A sensitive and specific sandwich ELISA was developed for the diagnosis of Glanzmann's thrombasthenia (GT) and the heterozygote carriers of the disease using whole blood platelets. The assay used anti-CD36 antibody to capture platelets from platelet-rich plasma which was subsequently treated with a bioengineered disintegrin/alkaline phosphatase hybrid protein specific for GP IIb/IIIa. The test allows large number of samples to be typed and can also be used on stored samples. The assay correctly diagnosed 40 normal healthy individuals, 10 GT cases, 10 heterozygotes, 3 Bernard-Soulier syndrome cases and 2 type 3 GT cases. ELISA plates were stable at room temperature up to 3 weeks without any loss of activity. This novel and simple test can be widely used for heterozygote detection besides diagnosing GT cases without using a sophisticated flow cytometer or a platelet aggregometer and has wide applicability in countries like India where many of these cases remain undiagnosed due to the lack of diagnostic facilities.