The inflammasomes are multiprotein complexes sensing tissue damage and infectious agents to initiate innate immune responses. Different inflammasomes containing distinct sensor molecules exist. The ...NLRP3 inflammasome is unique as it detects a variety of danger signals. It has been reported that NLRP3 is recruited to mitochondria-associated endoplasmic reticulum membranes (MAMs) and is activated by MAM-derived effectors. Here, we show that in response to inflammasome activators, MAMs localize adjacent to Golgi membranes. Diacylglycerol (DAG) at the Golgi rapidly increases, recruiting protein kinase D (PKD), a key effector of DAG. Upon PKD inactivation, self-oligomerized NLRP3 is retained at MAMs adjacent to Golgi, blocking assembly of the active inflammasome. Importantly, phosphorylation of NLRP3 by PKD at the Golgi is sufficient to release NLRP3 from MAMs, resulting in assembly of the active inflammasome. Moreover, PKD inhibition prevents inflammasome autoactivation in peripheral blood mononuclear cells from patients carrying NLRP3 mutations. Hence, Golgi-mediated PKD signaling is required and sufficient for NLRP3 inflammasome activation.
SARS-CoV-2 non-structural protein Nsp14 is a highly conserved enzyme necessary for viral replication. Nsp14 forms a stable complex with non-structural protein Nsp10 and exhibits exoribonuclease and ...N7-methyltransferase activities. Protein-interactome studies identified human sirtuin 5 (SIRT5) as a putative binding partner of Nsp14. SIRT5 is an NAD-dependent protein deacylase critical for cellular metabolism that removes succinyl and malonyl groups from lysine residues. Here we investigated the nature of this interaction and the role of SIRT5 during SARS-CoV-2 infection. We showed that SIRT5 interacts with Nsp14, but not with Nsp10, suggesting that SIRT5 and Nsp10 are parts of separate complexes. We found that SIRT5 catalytic domain is necessary for the interaction with Nsp14, but that Nsp14 does not appear to be directly deacylated by SIRT5. Furthermore, knock-out of SIRT5 or treatment with specific SIRT5 inhibitors reduced SARS-CoV-2 viral levels in cell-culture experiments. SIRT5 knock-out cells expressed higher basal levels of innate immunity markers and mounted a stronger antiviral response, independently of the Mitochondrial Antiviral Signaling Protein MAVS. Our results indicate that SIRT5 is a proviral factor necessary for efficient viral replication, which opens novel avenues for therapeutic interventions.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Mitochondria are highly dynamic organelles subjected to fission and fusion events. During mitosis, mitochondrial fission ensures equal distribution of mitochondria to daughter cells. If and how this ...process can actively drive mitotic progression remains largely unknown. Here, we discover a pathway linking mitochondrial fission to mitotic progression in mammalian cells. The mitochondrial fission factor (MFF), the main mitochondrial receptor for the Dynamin-related protein 1 (DRP1), is directly phosphorylated by Protein Kinase D (PKD) specifically during mitosis. PKD-dependent MFF phosphorylation is required and sufficient for mitochondrial fission in mitotic but not in interphasic cells. Phosphorylation of MFF is crucial for chromosome segregation and promotes cell survival by inhibiting adaptation of the mitotic checkpoint. Thus, PKD/MFF-dependent mitochondrial fission is critical for the maintenance of genome integrity during cell division.
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•PKD and MFF drive mitotic mitochondrial fission and chromosome segregation•PKD but not AMPK directly phosphorylates MFF specifically during mitosis•PKD-phosphorylated MFF is required and sufficient for mitotic mitochondrial fission•PKD-phosphorylated MFF protects cells from mitotic checkpoint slippage
Pangou et al. show that PKD directly phosphorylates MFF specifically during mitosis to promote mitochondrial fission and proper chromosome segregation. PKD-dependent MFF phosphorylation inhibits adaptation of the mitotic checkpoint and provides a survival benefit to proliferating cells.
The posttranslational modification lysine malonylation is found in many proteins, including histones. However, it remains unclear whether histone malonylation is regulated or functionally relevant. ...Here, we report that availability of malonyl-co-enzyme A (malonyl-CoA), an endogenous malonyl donor, affects lysine malonylation, and that the deacylase SIRT5 selectively reduces malonylation of histones. To determine if histone malonylation is enzymatically catalyzed, we knocked down each of the 22 lysine acetyltransferases (KATs) to test their malonyltransferase potential. KAT2A knockdown in particular reduced histone malonylation levels. By mass spectrometry, H2B_K5 was highly malonylated and regulated by SIRT5 in mouse brain and liver. Acetyl-CoA carboxylase (ACC), the malonyl-CoA producing enzyme, was partly localized in the nucleolus, and histone malonylation increased nucleolar area and ribosomal RNA expression. Levels of global lysine malonylation and ACC expression were higher in older mouse brains than younger mice. These experiments highlight the role of histone malonylation in ribosomal gene expression.
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•Malonyl-CoA availability affects lysine malonylation•SIRT5 and KAT2A regulate histone malonylation•Histone malonylation increases ribosomal RNA expression•Lysine malonylation increases with age in mouse brain
Biological sciences; Molecular biology; Omics; Proteomics
Obesity and ageing predispose to numerous, yet overlapping chronic diseases. For example, metabolic abnormalities, including insulin resistance (IR) and type 2 diabetes (T2D) are important causes of ...morbidity and mortality. Low-grade chronic inflammation of tissues, such as the liver, visceral adipose tissue and neurological tissues, is considered a significant contributor to these chronic diseases. Thus, it is becoming increasingly important to understand what drives this inflammation in affected tissues. Recent evidence, especially in the context of obesity, suggests that the intestine plays an important role as the gatekeeper of inflammatory stimuli that ultimately fuels low-grade chronic tissue inflammation. In addition to metabolic diseases, abnormalities in the intestinal mucosal barrier have been linked to a range of other chronic inflammatory conditions, such as neurodegeneration and ageing. The flow of inflammatory stimuli from the gut is in part controlled by local immunological inputs impacting the intestinal barrier. Here, we will review the impact of obesity and ageing on the intestinal immune system and its downstream consequences on gut barrier function, which is strongly implicated in the pathogenesis of obesity and age-related diseases. In particular, we will discuss the effects of age-related intestinal dysfunction on neurodegenerative diseases.
Digenic Alport Syndrome Savige, Judy; Renieri, Alessandra; Ars, Elisabet ...
Clinical journal of the American Society of Nephrology,
11/2022, Letnik:
17, Številka:
11
Journal Article
Recenzirano
Odprti dostop
Digenic Alport syndrome refers to the inheritance of pathogenic variants in
plus
or
or in
plus
Where digenic Alport syndrome includes a pathogenic
variant, the consequences depend on the sex of the ...affected individual,
variant "severity," and the nature of the
or
change. A man with a pathogenic
variant has all his collagen IV
3
4
5-heterotrimers affected, and an additional
or
variant may not worsen disease. A woman with a pathogenic
variant has on average 50% of her heterotrimers affected, which is increased to 75% with a further
or
variant and associated with a higher risk of proteinuria. In digenic Alport syndrome with pathogenic
and
variants, 75% of the heterotrimers are affected. The
and
genes occur head-to-head on chromosome 2, and inheritance is autosomal dominant when both variants affect the same chromosome (
) or recessive when they affect different chromosomes (
). This form of digenic disease results in increased proteinuria and a median age of kidney failure intermediate between autosomal dominant and autosomal recessive Alport syndrome. Previous guidelines have suggested that all pathogenic or likely pathogenic digenic variants should be identified and reported. Affected family members should be identified, treated, and discouraged from kidney donation. Inheritance within a family is easier to predict if the two variants are considered independently and if
and
variants are known to be inherited on the same or different chromosomes.
A study of 269 children enrolled into a National Registry for children with persistent glomerular hematuria identified 131 individuals with genetically confirmed X-linked Alport Syndrome. A single ...variant c.1871G>A p.Gly624Asp (G624D) in COL4A5 was predominant and accounted for 39% of X-linked Alport Syndrome in unrelated Polish families (44 of 113). To evaluate its origins, the genetic variation in a 2.79 Mb segment encompassing the COL4A5 locus on chromosome X was assessed. All G624D alleles were found on the same rare haplotype background, indicating a founder effect dating back to the 12-13th century. The phenotypic data of 131 children with X-linked Alport Syndrome and their 195 affected adult relatives revealed that the G624D variant was associated with a significantly milder clinical course in comparison to other pathogenic COL4A5 variants. Furthermore the clinical course of this genetically uniform cohort was milder than that observed in individuals with other COL4A5 missense mutations. In spite of the benign clinical manifestation throughout childhood and early adulthood, the G624D variant confers significant risk for both kidney failure and deafness in males, albeit 20-30 years later than that observed in individuals with other COL4A5 pathogenic variants (50% cumulative risk of starting dialysis at 54 years (95% confidence interval: 50-62) v. 26 years (95% confidence interval: 22-30)). Thus, males with G624D are candidates for existing and emerging therapies for Alport Syndrome.
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Plusieurs études ont découvert et renforcé l'implication de la dynamique mitochondriale dans le cancer. J'ai découvert un rôle inattendu des protéines kinases de la famille PKD dans la fission ...mitochondriale. La perte de l'activité PKD a conduit à un blocage de la fission et a entraîné une élongation significative des mitochondries par fusion continue. D'un point de vue mécanique, nous avons montré que les protéines PKD régulent la dynamique mitochondriale en activant le facteur de fission mitochondrial (MFF) par phosphorylation de plusieurs sites. MFF agit comme un récepteur principal de la GTPase DRP1, qui resserre les mitochondries, et il est essentiel à une bonne division mitochondriale. Les trois membres de la famille PKD peuvent phosphoryler MFF. La phosphorylation de MFF est médiée par PKD et la fragmentation mitochondriale se produit pendant la mitose. Comme démontré dans études sur les phosphoprotéomes, la phosphorylation du MFF est augmentée dans les cancers très mitotiques. Ainsi, l'axe de signalisation PKD-MFF régulant la dynamique mitochondriale en mitose pourrait devenir une voie thérapeutique attrayante pour le traitement du cancer.
Over the last two decades, multiple studies have uncovered and strengthen the implication of mitochondrial dynamics in cancer. During my thesis, I discovered an unanticipated role for the PKD kinase family in mitochondrial fission. Loss of PKD activity led to blockade of mitochondrial fission and resulted in a significant elongation of mitochondria by unopposed fusion. Mechanistically, we showed that PKDs regulated mitochondrial dynamics by activating the mitochondrial fission factor (MFF) through phosphorylation of multiple sites. MFF acts as a main receptor for the large GTPase DRP1, which constricts mitochondria, and it is critical for proper mitochondrial division. All three PKD family members could phosphorylate MFF. PKD-mediated MFF phosphorylation and mitochondrial fragmentation occurred specifically during mitosis. As MFF phosphorylation was found to be significantly upregulated in highly mitotic cancers, which was evidenced in several global phosphoproteome studies, the discovered PKD-MFF signaling axis regulating mitochondrial dynamics in mitosis could become an attractive therapeutic avenue for cancer treatment.
The article presents research experiences from a qualitative project concerning foreign-born academics in Poland, constituting one category of highly skilled migrants. It describes consecutive stages ...of the research process, problematizing methodological issues such as using the onomastic method and languages other than Polish, as well as not stigmatizing minority groups. In every part we make recommendations about possible decisions in further research projects.
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