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Age‐induced decline in osteogenic potential of bone marrow mesenchymal stem cells (BMSCs) potentiates osteoporosis and increases the risk for bone fractures. Despite epidemiology studies reporting concurrent development of vascular and bone diseases in the elderly, the underlying mechanisms for the vascular‐bone cross‐talk in aging are largely unknown. In this study, we show that accelerated endothelial aging deteriorates bone tissue through paracrine repression of Wnt‐driven‐axis in BMSCs. Here, we utilize physiologically aged mice in conjunction with our transgenic endothelial progeria mouse model (Hutchinson‐Gilford progeria syndrome; HGPS) that displays hallmarks of an aged bone marrow vascular niche. We find bone defects associated with diminished BMSC osteogenic differentiation that implicate the existence of angiocrine factors with long‐term inhibitory effects. microRNA‐transcriptomics of HGPS patient plasma combined with aged‐vascular niche analyses in progeria mice reveal abundant secretion of Wnt‐repressive microRNA‐31‐5p. Moreover, we show that inhibition of microRNA‐31‐5p as well as selective Wnt‐activator CHIR99021 boosts the osteogenic potential of BMSCs through de‐repression and activation of the Wnt‐signaling, respectively. Our results demonstrate that the vascular niche significantly contributes to osteogenesis defects in aging and pave the ground for microRNA‐based therapies of bone loss in elderly. [ABSTRACT FROM AUTHOR]

A-type lamins form a filamentous meshwork beneath the nuclear membrane that anchors large heterochromatic genomic regions at the nuclear periphery. A-type lamins also exist as a dynamic, non-filamentous pool in the nuclear interior, where they interact with lamin-associated polypeptide 2 alpha (LAP2α). Both proteins associate with largely overlapping euchromatic genomic regions in the nucleoplasm, but the functional significance of this interaction is poorly understood. Here, we report that LAP2α relocates towards regions containing myogenic genes in the early stages of muscle differentiation, possibly facilitating efficient gene regulation, while lamins A and C mostly associate with genomic regions away from these genes. Strikingly, upon depletion of LAP2α, A-type lamins spread across active chromatin and accumulate at regions of active H3K27ac and H3K4me3 histone marks in the vicinity of myogenic genes whose expression is impaired in the absence of LAP2α. Reorganization of A-type lamins on chromatin is accompanied by depletion of the active chromatin mark H3K27ac and a significantly impaired myogenic differentiation. Thus, the interplay of LAP2α and A-type lamins is crucial for proper positioning of intranuclear lamin A/C on chromatin to allow efficient myogenic differentiation., (© The Author(s) 2024. Published by Oxford University Press on behalf of Nucleic Acids Research.)