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M. M. Kapustei and P. V. Slyusarchuk
Theor. Probability and Math. Statist. 99 (2020), 101-111.
Abstract, references and article information

Recently, I have been re-reading Michel Houellebecq’s 2015 novel Submission. It’s about a hedonistic literature professor who sleeps with his students, has the diet of a frat boy, and occasionally does “work” researching an obscure (at least, to me) 19th-century … Continue reading →

Chief Secretary Matthew Cheung today chaired the fourth meeting of the Anti-epidemic Fund Steering Committee, during which the funding commitment for 33 measures under the second-round of the fund was approved.

The Legislative Council Finance Committee last Saturday approved a funding application of $137.5 billion, including an injection of $120.5 billion to the Anti-epidemic Fund to roll out the second round of measures to provide further assistance or relief to the public and enterprises hard hit by the current epidemic or affected by anti-epidemic measures.

Mr Cheung said: "The pandemic has caused an unprecedented impact on Hong Kong's economy and various sectors have been hard hit.

“The Government will take resolute and unprecedented measures to expeditiously relieve the imminent needs of the businesses and members of the public.

"To provide assistance and relief to relevant enterprises and members of the public as soon as possible, I have asked the bureaus and departments to implement the measures at full steam to address the pressing needs of the community promptly and achieve the effect of safeguarding jobs and supporting enterprises."

Separately, the Education Bureau said the Finance Committee’s approval of the funding application for the second round of the fund and other relief measures included a one-off interest-free deferral of loan repayment for two years to self-financing post-secondary institutions under the Start-up Loan Scheme, non-profit-making international schools and student loan repayers.

All borrowers of the Tertiary Student Finance Scheme - Publicly-funded Programmes, Financial Assistance Scheme for Post-secondary Students, Non-means-tested Loan Scheme for Full-time Tertiary Students, Non-means-tested Loan Scheme for Post-secondary Students and Extended Non-means-tested Loan Scheme will be offered an interest-free deferral of loan repayment from April 1 this year to March 31, 2022, including their loan instalments and interests.

The annual administrative fee of $180 charged on the non-means-tested loan repayers during the suspension period will be waived. The risk-adjusted-factor rate for setting the interest rate will also be maintained at zero.

Additionally, support for the construction sector will be enhanced.

The Development Bureau today said a one-off subsidy of $7,500 will be offered to each eligible construction worker.

More than 530,000 workers will benefit from the subsidy, including workers of construction sites as well as those registered under the Electrical & Mechanical Services Department, the Buildings Department, the Water Supplies Department and the Fire Services Department.

At the same time, a one-off subsidy will be provided to 30,000 construction-related enterprises, generally small-scaled, which cannot benefit from the first round of the Anti-epidemic Fund.

Each eligible contractor, specialist contractor, works contractor and supplier can receive a one-off subsidy of $20,000, while minor works contractors, registered contractors of electrical, gas, lift, escalator and fire service installation along with suppliers of construction-related machinery and equipment rental can receive $10,000 each.

About 600 consultant firms offering engineering, architectural and related professional services will receive a subsidy of $50,000 each to support professionals in the sector.

The Government will also provide a direct subsidy of $3 million to each non-profit-making organisation running the 10 projects under the Revitalising Historic Buildings Through Partnership Scheme, PMQ and the Energizing Kowloon East - Fly the Flyover Operation.

The Government said it will continue to spare no effort in improving workers' benefits and protection and enhance occupational safety and health in various industries at a pace commensurate with Hong Kong's overall socio-economic development.

The Government made the statement today in response to the demands of different labour groups, noting that it would take into account both employees' interests and employers' abilities to afford the benefits, despite the severe blow dealt by the COVID-19 epidemic to the local economy.

"The seasonally adjusted unemployment and underemployment rates for January to March this year have soared to their highest levels in recent years. The labour market will continue to face significant pressure in the near term.

“The Government has rolled out relief measures of unprecedented scale, including the one-off measures in the 2020-21 Budget and two rounds of measures under the Anti-epidemic Fund (AEF) totalling $287.5 billion, with a view to preserving the vitality of the economy and relieving people's financial burden.

“The Government will launch as soon as possible the Employment Support Scheme under the second round of the AEF, with a total commitment of $81 billion, to provide time-limited financial support to employers to help them retain employees who will otherwise be made redundant.”

Moreover, the Government explained that it has earmarked $6 billion to create around 30,000 time-limited jobs in the public and private sectors in the coming two years for people with different skills and academic qualifications.

It emphasised that the Labour Department will raise the ceiling of on-the-job training allowance payable to employers under the Employment Programme for the Elderly & Middle-aged, the Youth Employment & Training Programme and the Work Orientation & Placement Scheme in the second half of this year.

It will also launch a pilot scheme to encourage eligible participants of these programmes to undergo and complete the training by offering a retention allowance.

On improvements to other labour benefits, the Government pointed out that it is working at full steam on the preparatory work to abolish the arrangement of 'offsetting' severance payments and long service payments with employers' mandatory contributions under the Mandatory Provident Fund System.

It stressed that it will strive to introduce the enabling bill into the Legislative Council by the end of this year, aiming to secure its passage by 2022.

Meanwhile, the Government introduced the Employment (Amendment) Bill 2019 into LegCo on January 8 this year. The bill, which proposes to extend statutory maternity leave by four weeks, is now being handled by the LegCo Panel on Manpower.

The Chief Executive announced on January 14 this year 10 new initiatives on improving people's livelihood, one of which is to increase progressively the number of statutory holidays so that it will be on par with that of general holidays.

The Government stated that it will work out the relevant proposal, invite the Labour Advisory Board to discuss, and will facilitate and support its work.

The Minimum Wage Commission is conducting a new round of review on the Statutory Minimum Wage rate and will submit a report on its recommendation to the Chief Executive in Council by end-October.

The Government added that it attaches great importance to employees' occupational safety and health.

It said the Labour Department has been adjusting its strategies of inspection and enforcement, publicity and promotion, education and training according to the occupational safety and health risk levels of different industries as well as taking sufficient precautionary measures to prevent accidents by driving employers and employees to work together.

(To watch the full media session with sign language interpretation, click here.)

Chief Executive Carrie Lam today said the prevailing chairwoman of the Legislative Council House Committee should have the responsibility and power to deal with the matters of the committee.

Mrs Lam made the statement ahead of the Executive Council meeting this morning, noting LegCo President Andrew Leung had sought advice from outside senior counsel on how to address the delay in electing the committee’s chairman.

She said the senior counsels have observed that many of the matters raised in the House Committee’s meetings by the presiding member in the past six months have been irrelevant to the purpose of electing the committee’s chairman and vice-chairman.

“The second point that the senior counsels have observed during their very detailed scrutiny of the deliberations is that there was at least one occasion on March 13 in the House Committee meeting that gave people a very clear impression that the delaying of the election by the presiding member of the House Committee was quite deliberate and deliberate for political reasons.

“And the third thing that I observed from the senior counsels’ advice is, having regard to all these circumstances, they are of the firm view - this is the word taken from the senior counsels’ statement - that the prevailing chairwoman of the House Committee should have the responsibility and the power to deal with the business of the House Committee.”

The Chief Executive added that she expects the committee’s prevailing chairwoman Starry Lee to exercise her power.

Chief Secretary Matthew Cheung today chaired the Anti-epidemic Fund Steering Committee's fifth meeting to examine the implementation progress of the host of measures launched under the fund.

The committee noted the details of over 20 second-round relief measures have been announced since the Legislative Council Finance Committee approved the $120.5 billion injection to the fund on April 18.

Other measures will be launched as soon as possible to provide timely relief to the affected sectors and individuals. 

The committee also noted that the fund has paid out over $13 billion, and many businesses and members of the public have gradually received subsidies.

Mr Cheung said the measures aim to preserve employment and assist the self-employed, provide additional relief to those sectors hard hit by the pandemic and pave the way for the post-pandemic economic recovery. 

“We will continue to process applications and disburse subsidies as soon as possible to help businesses and members of the public tackle the challenges caused by the pandemic and to support enterprises, safeguard jobs and relieve people’s burden," he stressed. 

For the Retail Sector Subsidy Scheme which provides a one-off subsidy of $80,000 to eligible retailers, about 93,000 applications were received.

The committee was pleased to note that the scheme has been disbursing subsidies progressively and over $2.7 billion in subsidies have been approved so far, involving about 33,000 applications.

The Development Bureau today briefed the Land & Development Advisory Committee on the major recommendations of the Planning & Urban Design Review for Developments at Kai Tak Runway Tip (KTRT).

Members noted the planning objectives, design principles and key study recommendations for the KTRT developments, including the existing and planned public open spaces as well as the Tourism Node site included in the 2020-21 Land Sale Programme.

They generally supported the recommendations of the KTRT study and provided comments on various aspects, such as ways to attract people to KTRT, the connectivity to and within the area, and promotion of healthy city and kid-friendly concepts.

The committee was also briefed on the proposed two-envelope tender arrangement, which refers to evaluation of both design and price proposals, for disposal of Site 3 of the New Central Harbourfront.

With a total area of 4.75 hectares, the site will comprise a commercial development in separate blocks mainly for office and retail, with a total gross floor area not exceeding 150,000 sq m, to be built alongside a spacious public open space of no less than 25,000 sq m to be opened round-the-clock.

There will be a continuous landscaped deck spanning across the site in a north-south direction, allowing visitors to walk all the way from the hinterland of the Central Business District to the harbourfront.

While noting that the two-envelope approach was rather unconventional for government land sale, members agreed that the approach would allow both quality and price considerations to be taken into account, and the setting of a reserve price would ensure reasonable protection to public revenue.

VOLUME 285 (2010) PAGES 13742–13747In Fig. 1E, passage 10, the splicing of a non-adjacent lane from the same immunoblot was not marked. This error has now been corrected and does not affect the results or conclusions of this work.jbc;295/16/5533/F1F1F1Figure 1E.

VOLUME 295 (2020) PAGES 3285–3300An incorrect graph was used in Fig. 5C. This error has now been corrected. Additionally, some of the statistics reported in the legend and text referring to Fig. 5C were incorrect. The F statistics for Fig. 5C should state Fken(3,16) = 7.454, p < 0.01; FCCCP(1,16) = 102.9, p < 0.0001; Finteraction(3,16) = 7.480, p < 0.01. This correction does not affect the results or conclusions of this work.jbc;295/17/5835/F5F1F5Figure 5C.

Accumulating evidence suggests that brown adipose tissue (BAT) is a potential therapeutic target for managing obesity and related diseases. PGAM family member 5, mitochondrial serine/threonine protein phosphatase (PGAM5), is a protein phosphatase that resides in the mitochondria and regulates many biological processes, including cell death, mitophagy, and immune responses. Because BAT is a mitochondria-rich tissue, we have hypothesized that PGAM5 has a physiological function in BAT. We previously reported that PGAM5-knockout (KO) mice are resistant to severe metabolic stress. Importantly, lipid accumulation is suppressed in PGAM5-KO BAT, even under unstressed conditions, raising the possibility that PGAM5 deficiency stimulates lipid consumption. However, the mechanism underlying this observation is undetermined. Here, using an array of biochemical approaches, including quantitative RT-PCR, immunoblotting, and oxygen consumption assays, we show that PGAM5 negatively regulates energy expenditure in brown adipocytes. We found that PGAM5-KO brown adipocytes have an enhanced oxygen consumption rate and increased expression of uncoupling protein 1 (UCP1), a protein that increases energy consumption in the mitochondria. Mechanistically, we found that PGAM5 phosphatase activity and intramembrane cleavage are required for suppression of UCP1 activity. Furthermore, utilizing a genome-wide siRNA screen in HeLa cells to search for regulators of PGAM5 cleavage, we identified a set of candidate genes, including phosphatidylserine decarboxylase (PISD), which catalyzes the formation of phosphatidylethanolamine at the mitochondrial membrane. Taken together, these results indicate that PGAM5 suppresses mitochondrial energy expenditure by down-regulating UCP1 expression in brown adipocytes and that its phosphatase activity and intramembrane cleavage are required for UCP1 suppression.

Knowledge of the molecular events in mitochondrial DNA (mtDNA) replication is crucial to understanding the origins of human disorders arising from mitochondrial dysfunction. Twinkle helicase is an essential component of mtDNA replication. Here, we employed atomic force microscopy imaging in air and liquids to visualize ring assembly, DNA binding, and unwinding activity of individual Twinkle hexamers at the single-molecule level. We observed that the Twinkle subunits self-assemble into hexamers and higher-order complexes that can switch between open and closed-ring configurations in the absence of DNA. Our analyses helped visualize Twinkle loading onto and unloading from DNA in an open-ringed configuration. They also revealed that closed-ring conformers bind and unwind several hundred base pairs of duplex DNA at an average rate of ∼240 bp/min. We found that the addition of mitochondrial single-stranded (ss) DNA–binding protein both influences the ways Twinkle loads onto defined DNA substrates and stabilizes the unwound ssDNA product, resulting in a ∼5-fold stimulation of the apparent DNA-unwinding rate. Mitochondrial ssDNA-binding protein also increased the estimated translocation processivity from 1750 to >9000 bp before helicase disassociation, suggesting that more than half of the mitochondrial genome could be unwound by Twinkle during a single DNA-binding event. The strategies used in this work provide a new platform to examine Twinkle disease variants and the core mtDNA replication machinery. They also offer an enhanced framework to investigate molecular mechanisms underlying deletion and depletion of the mitochondrial genome as observed in mitochondrial diseases.

S-Palmitoylation is a reversible post-translational lipid modification that dynamically regulates protein functions. Voltage-gated sodium channels are subjected to S-palmitoylation and exhibit altered functions in different S-palmitoylation states. Our aim was to investigate whether and how S-palmitoylation regulates Nav1.6 channel function and to identify S-palmitoylation sites that can potentially be pharmacologically targeted. Acyl-biotin exchange assay showed that Nav1.6 is modified by S-palmitoylation in the mouse brain and in a Nav1.6 stable HEK 293 cell line. Using whole-cell voltage clamp, we discovered that enhancing S-palmitoylation with palmitic acid increases Nav1.6 current, whereas blocking S-palmitoylation with 2-bromopalmitate reduces Nav1.6 current and shifts the steady-state inactivation in the hyperpolarizing direction. Three S-palmitoylation sites (Cys1169, Cys1170, and Cys1978) were identified. These sites differentially modulate distinct Nav1.6 properties. Interestingly, Cys1978 is exclusive to Nav1.6 among all Nav isoforms and is evolutionally conserved in Nav1.6 among most species. Cys1978 S-palmitoylation regulates current amplitude uniquely in Nav1.6. Furthermore, we showed that eliminating S-palmitoylation at specific sites alters Nav1.6-mediated excitability in dorsal root ganglion neurons. Therefore, our study reveals S-palmitoylation as a potential isoform-specific mechanism to modulate Nav activity and neuronal excitability in physiological and diseased conditions.

tRNAs universally carry a CCA nucleotide triplet at their 3'-ends. In eukaryotes, the CCA is added post-transcriptionally by the CCA-adding enzyme (CAE). The mitochondrion of the parasitic protozoan Trypanosoma brucei lacks tRNA genes and therefore imports all of its tRNAs from the cytosol. This has generated interest in the tRNA modifications and their distribution in this organism, including how CCA is added to tRNAs. Here, using a BLAST search for genes encoding putative CAE proteins in T. brucei, we identified a single ORF, Tb927.9.8780, as a potential candidate. Knockdown of this putative protein, termed TbCAE, resulted in the accumulation of truncated tRNAs, abolished translation, and inhibited both total and mitochondrial CCA-adding activities, indicating that TbCAE is located both in the cytosol and mitochondrion. However, mitochondrially localized tRNAs were much less affected by the TbCAE ablation than the other tRNAs. Complementation assays revealed that the N-terminal 10 amino acids of TbCAE are dispensable for its activity and mitochondrial localization and that deletion of 10 further amino acids abolishes both. A growth arrest caused by the TbCAE knockdown was rescued by the expression of the cytosolic isoform of yeast CAE, even though it was not imported into mitochondria. This finding indicated that the yeast enzyme complements the essential function of TbCAE by adding CCA to the primary tRNA transcripts. Of note, ablation of the mitochondrial TbCAE activity, which likely has a repair function, only marginally affected growth.

Coenzyme Q (Qn) is a vital lipid component of the electron transport chain that functions in cellular energy metabolism and as a membrane antioxidant. In the yeast Saccharomyces cerevisiae, coq1–coq9 deletion mutants are respiratory-incompetent, sensitive to lipid peroxidation stress, and unable to synthesize Q6. The yeast coq10 deletion mutant is also respiratory-deficient and sensitive to lipid peroxidation, yet it continues to produce Q6 at an impaired rate. Thus, Coq10 is required for the function of Q6 in respiration and as an antioxidant and is believed to chaperone Q6 from its site of synthesis to the respiratory complexes. In several fungi, Coq10 is encoded as a fusion polypeptide with Coq11, a recently identified protein of unknown function required for efficient Q6 biosynthesis. Because “fused” proteins are often involved in similar biochemical pathways, here we examined the putative functional relationship between Coq10 and Coq11 in yeast. We used plate growth and Seahorse assays and LC-MS/MS analysis to show that COQ11 deletion rescues respiratory deficiency, sensitivity to lipid peroxidation, and decreased Q6 biosynthesis of the coq10Δ mutant. Additionally, immunoblotting indicated that yeast coq11Δ mutants accumulate increased amounts of certain Coq polypeptides and display a stabilized CoQ synthome. These effects suggest that Coq11 modulates Q6 biosynthesis and that its absence increases mitochondrial Q6 content in the coq10Δcoq11Δ double mutant. This augmented mitochondrial Q6 content counteracts the respiratory deficiency and lipid peroxidation sensitivity phenotypes of the coq10Δ mutant. This study further clarifies the intricate connection between Q6 biosynthesis, trafficking, and function in mitochondrial metabolism.

Barttin is the accessory subunit of the human ClC-K chloride channels, which are expressed in both the kidney and inner ear. Barttin promotes trafficking of the complex it forms with ClC-K to the plasma membrane and is involved in activating this channel. Barttin undergoes post-translational palmitoylation that is essential for its functions, but the enzyme(s) catalyzing this post-translational modification is unknown. Here, we identified zinc finger DHHC-type containing 7 (DHHC7) protein as an important barttin palmitoyl acyltransferase, whose depletion affected barttin palmitoylation and ClC-K-barttin channel activation. We investigated the functional role of barttin palmitoylation in vivo in Zdhhc7−/− mice. Although palmitoylation of barttin in kidneys of Zdhhc7−/− animals was significantly decreased, it did not pathologically alter kidney structure and functions under physiological conditions. However, when Zdhhc7−/− mice were fed a low-salt diet, they developed hyponatremia and mild metabolic alkalosis, symptoms characteristic of human Bartter syndrome (BS) type IV. Of note, we also observed decreased palmitoylation of the disease-causing R8L barttin variant associated with human BS type IV. Our results indicate that dysregulated DHHC7-mediated barttin palmitoylation appears to play an important role in chloride channel dysfunction in certain BS variants, suggesting that targeting DHHC7 activity may offer a potential therapeutic strategy for reducing hypertension.

Kindlins are focal adhesion proteins that regulate integrin activation and outside-in signaling. The kindlin family consists of three members, kindlin-1, -2, and -3. Kindlin-2 is widely expressed in multiple cell types, except those from the hematopoietic lineage. A previous study has reported that the Drosophila Fit1 protein (an ortholog of kindlin-2) prevents abnormal spindle assembly; however, the mechanism remains unknown. Here, we show that kindlin-2 maintains spindle integrity in mitotic human cells. The human neuroblastoma SH-SY5Y cell line expresses only kindlin-2, and we found that when SH-SY5Y cells are depleted of kindlin-2, they exhibit pronounced spindle abnormalities and delayed mitosis. Of note, acetylation of α-tubulin, which maintains microtubule flexibility and stability, was diminished in the kindlin-2–depleted cells. Mechanistically, we found that kindlin-2 maintains α-tubulin acetylation by inhibiting the microtubule-associated deacetylase histone deacetylase 6 (HDAC6) via a signaling pathway involving AKT Ser/Thr kinase (AKT)/glycogen synthase kinase 3β (GSK3β) or paxillin. We also provide evidence that prolonged hypoxia down-regulates kindlin-2 expression, leading to spindle abnormalities not only in the SH-SY5Y cell line, but also cell lines derived from colon and breast tissues. The findings of our study highlight that kindlin-2 regulates mitotic spindle assembly and that this process is perturbed in cancer cells in a hypoxic environment.