Project description:AFF4 was discovered as a scaffold protein of Super Elongation Complex (SEC) and exhibites an essential function on osteogenesis, tumorigenesis and odontogenesis. However, the adipogenic biological functions of AFF4 need further explorations. Here, we demonstrate that knockdown of AFF4 inhibits adipogenesis in both human mesenchymal stem cells (hMSCs) and lineage-committed 3T3-L1 preadipocytes. Conditional knocking down of Aff4 in transgenic mouse presents a thin body phenotype and impeded adipogenesis. Mechanistically, we define autophagy signaling as a crucial downstream of AFF4 through the combination of RNA-seq and ChIP-seq analyses. Depletion of AFF4 mediates the transcription of crutial autophagy genes ATG5 and ATG16L1. Simultaneous overexpression of ATG5 and ATG16L1 rescues the lineage commitment of AFF4-deficient cells. Our data elucidate that AFF4 is indispensable for adipogenic differentiation and reveal a novel mechanism for adipogenesis at transcriptional level.
Project description:Transcriptional elongation is a universal and critical step during gene expression. The super elongation complex (SEC) regulates the rapid transcriptional induction by mobilizing paused RNA polymerase II (Pol II). Dysregulation of SEC is closely associated with human diseases. However, the physiological role of SEC during development and homeostasis remains largely unexplored. Here we studied the function of SEC in adipogenesis by manipulating an essential scaffold protein AF4/FMR2 family member 4 (AFF4), which assembles and stabilizes SEC. Knockdown of AFF4 in human mesenchymal stem cells (hMSCs) and mouse 3T3-L1 preadipocytes inhibits cellular adipogenic differentiation. Overexpression of AFF4 enhances adipogenesis and ectopic adipose tissue formation. We further generate Fabp4-cre driven adipose-specific Aff4 knockout mice and find that AFF4 deficiency impedes adipocyte development and white fat depot formation. Mechanistically, we discover AFF4 regulates autophagy during adipogenesis. AFF4 directly binds to autophagy-related protein ATG5 and ATG16L1, and promotes their transcription. Depleting ATG5 or ATG16L1 abrogates adipogenesis in AFF4-overepressing cells, while overexpression of ATG5 and ATG16L1 rescues the impaired adipogenesis in Aff4-knockout cells. Collectively, our results unveil the functional importance of AFF4 in regulating autophagy and adipogenic differentiation, which broaden our understanding of the transcriptional regulation of adipogenesis.
Project description:Viruses manipulate cellular metabolism and macromolecule recycling processes like autophagy. Dysregulated metabolism might lead to excessive inflammatory and autoimmune responses as observed in severe and long COVID-19 patients. Here we show that SARS-CoV-2 modulates cellular metabolism and reduces autophagy. Accordingly, compound-driven induction of autophagy limits SARS-CoV-2 propagation. In detail, SARS-CoV-2-infected cells show accumulation of key metabolites, activation of autophagy inhibitors (AKT1, SKP2) and reduction of proteins responsible for autophagy initiation (AMPK, TSC2, ULK1), membrane nucleation, and phagophore formation (BECN1, VPS34, ATG14), as well as autophagosome-lysosome fusion (BECN1, ATG14 oligomers). Consequently, phagophore-incorporated autophagy markers LC3B-II and P62 accumulate, which we confirm in a hamster model and lung samples of COVID-19 patients. Single-nucleus and single-cell sequencing of patient-derived lung and mucosal samples show differential transcriptional regulation of autophagy and immune genes depending on cell type, disease duration, and SARS-CoV-2 replication levels. Targeting of autophagic pathways by exogenous administration of the polyamines spermidine and spermine, the selective AKT1 inhibitor MK-2206, and the BECN1-stabilizing anthelmintic drug niclosamide inhibit SARS-CoV-2 propagation in vitro with IC<sub>50</sub> values of 136.7, 7.67, 0.11, and 0.13 μM, respectively. Autophagy-inducing compounds reduce SARS-CoV-2 propagation in primary human lung cells and intestinal organoids emphasizing their potential as treatment options against COVID-19.
Project description:The P-TEFb-containing super elongation complex (SEC) plays the essential role in transcriptional elongation control. The AF4/FMR2 family members AFF1 and AFF4 are the central scaffold proteins of SEC, associated with different human diseases. However, their specific roles in transcriptional control remain unclear. Here, we report that AFF1 and AFF4 show distinct genomic distribution patterns around TSS. AFF1 binds upstream of TSS, while AFF4 is enriched downstream of TSS. Pol II occupancies are reduced genome-widely after depletion of AFF1, but not AFF4. Interestingly, in a subset of active genes with broad AFF4 binding signature, AFF4 disruption causes slow elongation and early termination, while AFF1 deletion mirrors the transcriptional defects observed in the fast Pol II mutant. Furthermore, AFF4 knockdown leads to increased AFF1 levels at chromatin, and vice versa. In summary, our data demonstrate that AFF1 and AFF4 function, to some extent, antagonistically to ensure proper Pol II transcription.
Project description:The P-TEFb-containing super elongation complex (SEC) plays the essential role in transcriptional elongation control. The AF4/FMR2 family members AFF1 and AFF4 are the central scaffold proteins of SEC, associated with different human diseases. However, their specific roles in transcriptional control remain unclear. Here, we report that AFF1 and AFF4 show distinct genomic distribution patterns around TSS. AFF1 binds upstream of TSS, while AFF4 is enriched downstream of TSS. Pol II occupancies are reduced genome-widely after depletion of AFF1, but not AFF4. Interestingly, in a subset of active genes with broad AFF4 binding signature, AFF4 disruption causes slow elongation and early termination, while AFF1 deletion mirrors the transcriptional defects observed in the fast Pol II mutant. Furthermore, AFF4 knockdown leads to increased AFF1 levels at chromatin, and vice versa. In summary, our data demonstrate that AFF1 and AFF4 function, to some extent, antagonistically to ensure proper Pol II transcription.
Project description:The P-TEFb-containing super elongation complex (SEC) plays the essential role in transcriptional elongation control. The AF4/FMR2 family members AFF1 and AFF4 are the central scaffold proteins of SEC, associated with different human diseases. However, their specific roles in transcriptional control remain unclear. Here, we report that AFF1 and AFF4 show distinct genomic distribution patterns around TSS. AFF1 binds upstream of TSS, while AFF4 is enriched downstream of TSS. Pol II occupancies are reduced genome-widely after depletion of AFF1, but not AFF4. Interestingly, in a subset of active genes with broad AFF4 binding signature, AFF4 disruption causes slow elongation and early termination, while AFF1 deletion mirrors the transcriptional defects observed in the fast Pol II mutant. Furthermore, AFF4 knockdown leads to increased AFF1 levels at chromatin, and vice versa. In summary, our data demonstrate that AFF1 and AFF4 function, to some extent, antagonistically to ensure proper Pol II transcription.
Project description:The P-TEFb-containing super elongation complex (SEC) plays the essential role in transcriptional elongation control. The AF4/FMR2 family members AFF1 and AFF4 are the central scaffold proteins of SEC, associated with different human diseases. However, their specific roles in transcriptional control remain unclear. Here, we report that AFF1 and AFF4 show distinct genomic distribution patterns around TSS. AFF1 binds upstream of TSS, while AFF4 is enriched downstream of TSS. Pol II occupancies are reduced genome-widely after depletion of AFF1, but not AFF4. Interestingly, in a subset of active genes with broad AFF4 binding signature, AFF4 disruption causes slow elongation and early termination, while AFF1 deletion mirrors the transcriptional defects observed in the fast Pol II mutant. Furthermore, AFF4 knockdown leads to increased AFF1 levels at chromatin, and vice versa. In summary, our data demonstrate that AFF1 and AFF4 function, to some extent, antagonistically to ensure proper Pol II transcription.
Project description:The P-TEFb-containing super elongation complex (SEC) plays the essential role in transcriptional elongation control. The AF4/FMR2 family members AFF1 and AFF4 are the central scaffold proteins of SEC, associated with different human diseases. However, their specific roles in transcriptional control remain unclear. Here, we report that AFF1 and AFF4 show distinct genomic distribution patterns around TSS. AFF1 binds upstream of TSS, while AFF4 is enriched downstream of TSS. Pol II occupancies are reduced genome-widely after depletion of AFF1, but not AFF4. Interestingly, in a subset of active genes with broad AFF4 binding signature, AFF4 disruption causes slow elongation and early termination, while AFF1 deletion mirrors the transcriptional defects observed in the fast Pol II mutant. Furthermore, AFF4 knockdown leads to increased AFF1 levels at chromatin, and vice versa. In summary, our data demonstrate that AFF1 and AFF4 function, to some extent, antagonistically to ensure proper Pol II transcription.
Project description:Loss-of-function mutations in Foxn1 or Aff4 cause similar defects in skin morphology. To determine whether these similar phenotypes result from similar changes in gene expression, skin from wild-type, Foxn1-null, or Aff4 conditional knockout (cko) mice was analysed by RNA-seq at a time when the animals were attempting to grow their first hair coats (P6).