Developmental cell最新文献

Solubility regulates protein function, but how it is governed by aging remains elusive. Here, we utilized mass spectrometry to define the relative composition of the soluble and insoluble tissue/organ fractions during mouse aging. In the young, there is a wide (∼100-1,000×) range of insoluble/soluble protein ratios that differ tissue-specifically. With aging, some proteins become relatively more insoluble, while others are conversely regulated or unaffected. Age-related insoluble/soluble changes are not merely dictated by histological similarity, diverge in related tissues with distinct degeneration propensities, and correlate tissue-specifically with structural features. Proteins that become age-insoluble in multiple organs include aggregation-prone circulating factors and ectopically expressed proteins. For instance, although primarily expressed by the epidermis, hornerin insolubility increases with aging in skeletal muscle, and experimental hornerin upregulation causes muscle weakness. Thus, age-insoluble proteins are useful biomarkers but can also contribute to age-related functional decline, highlighting a multifaceted remodeling of the insolubilome with aging.

Accessing ongoing RNA polymerase II (RNA Pol II) activity in specific cell types within intact tissue is critical to reveal regulatory mechanisms of development. We developed precision run-on in cell-type-specific in vivo system followed by sequencing (PReCIS-seq), a method combining Cre-inducible GFP tagging of endogenous RNA Pol II with transcriptional run-on and GFP immunoprecipitation, to map transcriptionally engaged RNA Pol II genome-wide in targeted cell types of mouse tissues. Applied to keratinocytes within intact skin, PReCIS-seq demonstrates that transcriptionally activated functions of biological transitions generally employ both RNA Pol II promoter-recruitment and promoter-proximal pause-release mechanisms. A global RNA Pol II regulatory polarization features extreme pausing levels at cellular safeguarding vs. lineage identity genes across development and homeostasis. This polarization is associated with distinct proximal-promoter structures, distinguishing high-paused genes with restricted RNA Pol II pause-release from low-paused genes undergoing rapid RNA Pol II firing into productive elongation. PReCIS-seq also identifies active enhancers based on divergent transcription. This approach enables high-resolution, cell-type-specific analysis of RNA Pol II dynamics in intact tissues across mammalian development, homeostasis, and disease.

Sepsis is a life-threatening condition characterized by a dysregulated host innate immune response to pathogen infection. Here, we identify a pathological role for bromodomain-containing 3 (BRD3) in driving septic shock by upregulating aconitate decarboxylase 1 (ACOD1) in monocytes and macrophages via a non-canonical pathway. Mechanistically, lipopolysaccharide triggers an interaction between BRD3 and tripartite motif containing 21 (TRIM21), which activates CREB binding lysine acetyltransferase (CREBBP) via its E3 ligase activity, facilitating CREBBP's binding to and acetylation of cyclic adenosine monophophate (cAMP)-response-element-binding protein 1 (CREB1). BRD3 then recognizes and phosphorylates acetylated CREB1 at the transcription-activating site, thereby upregulating ACOD1 transcription. In four murine models of infection, myeloid-specific Brd3 deletion (Brd3^Mye-/-) or pharmacological intervention using small-molecule inhibitor OTX015 confers significant protection, reducing systemic inflammation and organ injury, similar to the effects observed in Acod1^Mye-/- mice. In patients with sepsis, elevated BRD3 levels correlate with accelerated inflammation, increased disease severity, and a greater risk of in-hospital death. These findings establish BRD3 as a potential therapeutic target for managing infection-associated immune dysregulation.