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Hepatocellular carcinoma (HCC) is the most common primary liver cancer worldwide and no pharmacological treatment is available that can achieve complete remission of HCC. Phospholysine phosphohistidine inorganic pyrophosphate phosphatase (LHPP) is a recently identified HCC tumor suppressor gene which plays an important role in the development of HCC and its inactivation and reactivation has been shown to result in respectively HCC tumorigenesis and suppression. Small activating RNAs (saRNAs) have been used to achieve targeted activation of therapeutic genes for the restoration of their encoded protein through the RNAa mechanism. Here we designed and validated saRNAs that could activate LHPP expression at both the mRNA and protein levels in HCC cells. Activation of LHPP by its saRNAs led to the suppression of HCC proliferation, migration and the inhibition of Akt phosphorylation. When combined with targeted anticancer drugs ( e . g ., regorafenib), LHPP saRNA exhibited synergistic effect in inhibiting in vitro HCC proliferation and in vivo antitumor growth in a xenograft HCC model. Findings from this study provides further evidence for a tumor suppressor role of LHPP and potential therapeutic value of restoring the expression of LHPP by saRNA for the treatment of HCC.

Adhesion G protein-coupled receptors are elusive in terms of their structural information and ligands. Here, we solved the cryogenic-electron microscopy (cryo-EM) structure of apo-ADGRG2, an essential membrane receptor for maintaining male fertility, in complex with a Gs trimer. Whereas the formations of two kinks were determinants of the active state, identification of a potential ligand-binding pocket in ADGRG2 facilitated the screening and identification of dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate and deoxycorticosterone as potential ligands of ADGRG2. The cryo-EM structures of DHEA–ADGRG2–Gs provided interaction details for DHEA within the seven transmembrane domains of ADGRG2. Collectively, our data provide a structural basis for the activation and signaling of ADGRG2, as well as characterization of steroid hormones as ADGRG2 ligands, which might be used as useful tools for further functional studies of the orphan ADGRG2.The description of the cryo-EM structure of an orphan adhesion GPCR–Gs protein complex in apo state facilitates the screening and identification of potential ligands of ADGRG2.

Background: Cadmium (Cd), a common environmental heavy metal and endocrine disruptor, is known to exert toxic effects on the testes. However, the mechanisms accounting for its toxicity in mature spermatozoa remain unclear. Methods: Adult male C57BL/6 mice were orally administered with CdCl 2 for 5 weeks at 3 mg·kg -1 ·day -1 . Additionally, mouse spermatozoa were incubated in vitro with different doses of CdCl 2 (0, 10, 50, 250 µM). Several sperm functions including the sperm motility, viability and acrosome reaction (AR) ratio were then examined. Furthermore, the current and expression levels of both the sperm-specific Ca 2+ channel (CatSper) and the sperm-specific K + channel (KSper) were evaluated by patch-clamping and western blotting, respectively. Results: Our data showed that the motility, viability and AR of sperm exposed to cadmium significantly decreased in vivo and in vitro. Interestingly, these changes were correlated with changes in CatSper but not KSper. Conclusion: The findings indicate sperm dysfunction during both chronic and acute cadmium exposure as well as a specific role for CatSper in the reproductive toxicity of cadmium.

Following entry into the female reproductive tract, mammalian sperm undergo a maturation process termed capacitation that results in competence to fertilize ova. Associated with capacitation is an increase in membrane conductance to both Ca ²⁺ and K ⁺, leading to an elevation in cytosolic Ca ²⁺ critical for activation of hyperactivated swimming motility. In mice, the Ca ²⁺ conductance (alkalization-activated Ca ²⁺-permeable sperm channel, CATSPER) arises from an ensemble of CATSPER subunits, whereas the K ⁺ conductance (sperm pH-regulated K ⁺ current, KSPER) arises from a pore-forming ion channel subunit encoded by the slo3 gene (SLO3) subunit. In the mouse, both CATSPER and KSPER are activated by cytosolic alkalization and a concerted activation of CATSPER and KSPER is likely a common facet of capacitation-associated increases in Ca ²⁺ and K ⁺ conductance among various mammalian species. The properties of heterologously expressed mouse SLO3 channels differ from native mouse KSPER current. Recently, a potential KSPER auxiliary subunit, leucine-rich-repeat-containing protein 52 (LRRC52), was identified in mouse sperm and shown to shift gating of SLO3 to be more equivalent to native KSPER. Here, we show that genetic KO of LRRC52 results in mice with severely impaired fertility. Activation of KSPER current in sperm lacking LRRC52 requires more positive voltages and higher pH than for WT KSPER. These results establish a critical role of LRRC52 in KSPER channels and demonstrate that loss of a non-pore-forming auxiliary subunit results in severe fertility impairment. Furthermore, through analysis of several genotypes that influence KSPER current properties we show that in vitro fertilization competence correlates with the net KSPER conductance available for activation under physiological conditions. Significance Mammalian sperm fertility depends on coordinated activation of two sperm-specific ion channels, the alkalization-activated Ca ²⁺-permeable sperm channel and a sperm pH-regulated K ⁺ current (KSPER) channel; both are required for fertility. In the mouse, the KSPER channel is thought to involve a complex of a pore-forming ion channel protein and subunit encoded by the slo3 gene subunit and the leucine-rich-repeat-containing protein 52 (LRRC52) auxiliary subunit. We now show that KO of LRRC52 results in severely compromised fertility and shifts KSPER current activation away from the physiological range. Furthermore, utilizing genotypes with differing average amounts of KSPER current, we show that sperm fertility exhibits a steep dependence on the amount of available KSPER current. The results establish that LRRC52 is a critical determinant of sperm KSPER function and essential to support normal fertility.

Centenarians, who show mild infections and low incidence of tumors, are the optimal model to investigate healthy aging. However, longevity related immune characteristics has not been fully revealed largely due to lack of appropriate controls. In this study, single‐cell transcriptomic analysis of peripheral blood mononuclear cells (PBMCs) derived from seven centenarians (CEN), six centenarians’ offspring (CO), and nine offspring spouses or neighbors (Control, age‐matched to CO) are performed to investigate the shared immune features between CEN and CO. The results indicate that among all 12 T cell clusters, the cytotoxic‐phenotype‐clusters (CPC) and the naïve‐phenotype‐clusters (NPC) significantly change between CEN and ontrol. Compared to Control, both CEN and CO are characterized by depleted NPC and increased CPC, which is dominated by CD8+ T cells. Furthermore, CPC from CEN and CO share enhanced signaling pathways and transcriptional factors associated with immune response, and possesse similar T‐cell‐receptor features, such as high clonal expansion. Interestingly, rather than a significant increase in GZMK+ CD8 cells during aging, centenarians show accumulation of GZMB+ and CMC1+ CD8 T cells. Collectively, this study unveils an immune remodeling pattern reflected by both quantitative increase and functional reinforcement of cytotoxic T cells which are essential for healthy aging. Immune remodeling patterns of quantitative increase and functional reinforcement of cytotoxic T‐cells in centenarian and their offspring, assessed by single‐cell RNA sequencing, fluorescence activated cell sorting and T cell receptor sequencing, provides insight into successful interventions against aging and exposes the path for healthy aging.

KSper, a pH-dependent K+ current in mouse spermatozoa that is critical for fertility, is activated by alkalization in the range of pH 6.4–7.2 at membrane potentials between –50 and 0 mV. Although the KSper pore-forming subunit is encoded by the Slo3 gene, heterologously expressed Slo3 channels are largely closed at potentials negative to 0 mV at physiological pH. Here we identify a Slo3-associating protein, LRRC52 (leucine-rich repeat-containing 52), that shifts Slo3 gating into a range of voltages and pH values similar to that producing KSper current activation. Message for LRRC52, a homolog of the Slo1-modifying LRRC26 protein, is enriched in testis relative to other homologous LRRC subunits and is developmentally regulated in concert with that for Slo3. LRRC52 protein is detected only in testis. It is markedly diminished from Slo3–/– testis and completely absent from Slo3–/– sperm, indicating that LRRC52 expression is critically dependent on the presence of Slo3. We also examined the ability of other LRRC subunits homologous to LRRC26 and LRRC52 to modify Slo3 currents. Although both LRRC26 and LRRC52 are able to modify Slo3 function, LRRC52 is the stronger modifier of Slo3 function. Effects of other related subunits were weaker or absent. We propose that LRRC52 is a testis-enriched Slo3 auxiliary subunit that helps define the specific alkalization dependence of KSper activation. Together, LRRC52 and LRRC26 define a new family of auxiliary subunits capable of critically modifying the gating behavior of Slo family channels.

Aim: Argonaute2 (AGO2) protein is the active part of RNA-induced silencing complex, cleaving the target mRNA strand complementary to their bound siRNA. An increasing number of miRNAs has been identified as essential to angiogenesis of hepatocellular carcinoma (HCC). In this study we investigated how AGO2 affected HCC angiogenesis. Methods: Human HCC cell lines HepG2, Hep3B, Huh7, SMMC-7721, Bel-7404, MHCC97-H and LM-3, and human umbilical vein endothelial cells (HUVEC) were tested. The expression of AGO2 in HCC cells was knocked down with siRNA and restored using recombinant adenovirus expressing Ago2. The levels of relevant mRNAs and proteins were examined using RT-PCR, Western blot and EILSA. Nude mice were implanted with Huh7 or SMMC-7721 cells, and tumor volumes were measured. After the mice were euthanized, the xenograft tumors were used for immunohistological analysis. Results: In 6 HCC cell lines, AGO2 protein expression was significantly correlated with VEGF expression (r=+0.79), and with VEGF secretion (r=+0.852). Knockdown of Ago2 in Huh7 cells and SMMC-7721 cells substantially decreased VEGF expression, whereas the restoration of AGO2 reversed both VEGF expression and secretion. Furthermore, knockdown of Ago2 significantly up-regulated the expression of PTEN (a tumor suppressor involved in the inhibition of HCC angiogenesis), and vice versa. Moreover, the specific PTEN inhibitor bisperoxovanadate (7, 14, 28 nmol/L) dose-dependently restored the expression of VEGF and the capacity of HCC cells to induce HUVECs to form capillary tubule structures. In the xenograft nude mice, knockdown of Ago2 markedly suppressed the tumor growth and decreased PTEN expression and CD31-positive microvascular in the xenograft tumors. Conclusion: A direct relationship exists between the miRNA processing machinery AGO2 and HCC angiogenesis that is mediated by the AGO2/PTEN/VEGF signaling pathway. The results suggest the high value of Ago2 knockdown in anti-angiogenesis therapy for HCC.

Sperm-specific K+ ion channel (KSper) and Ca2+ ion channel (CatSper), whose elimination causes male infertility in mice, determine the membrane potential and Ca2+ influx, respectively. KSper and CatSper can be activated by cytosolic alkalization, which occurs during sperm going through the alkaline environment of the female reproductive tract. However, which intracellular pH (pHi) regulator functionally couples to the activation of KSper/CatSper remains obscure. Although Na+/H+ exchangers (NHEs) have been implicated to mediate pHi in sperm, there is a lack of direct evidence confirming the functional coupling between NHEs and KSper/CatSper. Here, 5-(N,N-dimethyl)-amiloride (DMA), an NHEs inhibitor that firstly proved not to affect KSper/CatSper directly, was chosen to examine NHEs function on KSper/CatSper in mouse sperm. The results of patch clamping recordings showed that, when extracellular pH was at the physiological level of 7.4, DMA application caused KSper inhibition and the depolarization of membrane potential when pipette solutions were not pH-buffered. In contrast, these effects were minimized when pipette solutions were pH-buffered, indicating that they solely resulted from pHi acidification caused by NHEs inhibition. Similarly, DMA treatment reduced CatSper current and intracellular Ca2+, effects also dependent on the buffer capacity of pH in pipette solutions. The impairment of sperm motility was also observed after DMA incubation. These results manifested that NHEs activity is coupled to the activation of KSper/CatSper under physiological conditions.

Mouse spermatozoa express a pH-dependent K⁺ current (KSper) thought to be composed of subunits encoded by the Slo3 gene. However, the equivalence of KSper and S/o3-dependent current remains uncertain, because heterologous expression of S/o3 results in currents that are less effectively activated by alkalization than are native KSper currents. Here, we show that genetic deletion of S/o3 abolishes all pH-dependent K⁺ current at physiological membrane potentials in corpus epididymal sperm. A residual pH-dependent outward current (l Kres ) is observed in Slo3 -/- sperm at potentials of > 0 mV. Differential inhibition of KSper/Slo3 and l kres by clofilium reveals that the amplitude of l Kres is similar in both wild-type (wt) and Slo3 -/- sperm. The properties of l Kres suggest that it likely represents outward monovalent cation flux through CatSper channels. Thus, KSper/Slo3 may account for essentially all mouse sperm K⁺ current and is the sole pH-dependent K⁺ conductance in these sperm. With physiological ionic gradients, alkalization depolarizes Slo3 -/- spermatozoa, presumably from CatSper activation, in contrast to Slo3/KSper-mediated hyperpolarization in wt sperm. Slo3 -/- male mice are infertile, but Slo3 -/- sperm exhibit some fertility within in vitro fertilization assays. Slo3 -/- sperm exhibit a higher incidence of morphological abnormalities accentuated by hypotonic challenge and also exhibit deficits in motility in the absence of bicarbonate, revealing a role of KSper under unstimulated conditions. Together, these results show that KSper/Slo3 is the primary spermatozoan K⁺ current, that KSper may play a critical role in acquisition of normal morphology and sperm motility when faced with hyperosmotic challenges, and that Slo3 is critical for fertility.

Background The pH and voltage-regulated Slo3 K+ channel, a homologue of the Ca2+- and voltage-regulated Slo1 K+ channel, is thought to be primarily expressed in sperm, but the properties of Slo3 studied in heterologous systems differ somewhat from the native sperm KSper pH-regulated current. There is the possibility that critical partners that regulate Slo3 function remain unidentified. The extensive amino acid identity between Slo3 and Slo1 suggests that auxiliary β subunits regulating Slo1 channels might coassemble with and modulate Slo3 channels. Four distinct β subunits composing the KCNMB family are known to regulate the function and expression of Slo1 Channels. Methodology/Principal Findings To examine the ability of the KCNMB family of auxiliary β subunits to regulate Slo3 function, we co-expressed Slo3 and each β subunit in heterologous expression systems and investigated the functional consequences by electrophysiological and biochemical analyses. The β4 subunit produced an 8–10 fold enhancement of Slo3 current expression in Xenopus oocytes and a similar enhancement of Slo3 surface expression as monitored by YFP-tagged Slo3 or biotin labeled Slo3. Neither β1, β2, nor β3 mimicked the ability of β4 to increase surface expression, although biochemical tests suggested that all four β subunits are competent to coassemble with Slo3. Fluorescence microscopy from β4 KO mice, in which an eGFP tag replaced the deleted exon, revealed that β4 gene promoter is active in spermatocytes. Furthermore, quantitative RT-PCR demonstrated that β4 and Slo3 exhibit comparable mRNA abundance in both testes and sperm. Conclusions/Significance These results argue that, for native mouse Slo3 channels, the β4 subunit must be considered as a potential interaction partner and, furthermore, that KCNMB subunits may have functions unrelated to regulation of the Slo1 α subunit.