👤 Joseph L Alcon

Progression in Alzheimer's disease (AD) involves three main interrelated biological axes-tau deposition, neurodegeneration, and neuroinflammation-that jointly drive cognitive decline. Although several cerebrospinal fluid (CSF) and plasma biomarkers along these axes are well validated for diagnosis, their value for prognosis remains uncertain. We assessed how baseline markers of each axis predict cognitive trajectories in biomarker-confirmed AD. We included 136 A + T + N + individuals (median follow-up = 24 months [IQR 12-24]; mean = 17.6 months [SD = 12.4]). Tau-deposition markers (CSF p-Tau181; plasma p-Tau181 and p-Tau217), neurodegeneration markers (CSF t-Tau; CSF and plasma neurofilament light chain, NfL) and a neuroinflammation marker (plasma glial fibrillary acidic protein, GFAP) were quantified using CLEIA, ELISA or Simoa, and stratified into tertiles. Participants were classified by age at onset, clinical phenotype, and APOE ε4 status. Cognition was assessed annually with a comprehensive neuropsychological battery. Linear mixed-effects models (MMRM) were used to test biomarker-cognition associations and interactions with clinical variables. Elevated CSF p-Tau181 and NfL levels were associated with greater decline in memory and executive function. Among plasma biomarkers, p-Tau217 and GFAP showed the strongest associations with widespread cognitive decline, particularly in language, visuospatial, and executive domains. These associations were independent of age at onset, clinical phenotype, and APOE ε4 status. Our findings highlight the potential prognostic value of fluid biomarkers in AD, especially CSF p-Tau181 and NfL, and plasma p-Tau217 and GFAP. These results suggest promise for improving disease monitoring, although prognostic utility at the individual level remains uncertain. Show less

Calcineurin is a serine/threonine protein phosphatase that plays a critical role in many physiologic processes such as T-cell activation, skeletal myocyte differentiation, and cardiac hypertrophy. We previously showed that active MEKK3 is capable of stimulating calcineurin/nuclear factor of activated T-cells (NFAT) signaling in cardiac myocytes through phosphorylation of modulatory calcineurin-interacting protein 1 (MCIP1). However, the protein kinases that function downstream of MEKK3 to mediate MCIP1 phosphorylation and the mechanism of MCIP1-mediated calcineurin regulation have not been defined. Here, we show that MEK5 and big MAP kinase 1 (BMK1) function downstream of MEKK3 in a signaling cascade that induces calcineurin activity through phosphorylation of MCIP1. Genetic studies showed that BMK1-deficient mouse lung fibroblasts failed to mediate MCIP1 phosphorylation and activate calcineurin/NFAT in response to angiotensin II, a potent NFAT activator. Conversely, restoring BMK1 to the deficient cells restored angiotensin II-mediated calcineurin/NFAT activation. Thus, using BMK1-deficient mouse lung fibroblast cells, we provided the genetic evidence that BMK1 is required for angiotensin II-mediated calcineurin/NFAT activation through MICP1 phosphorylation. Finally, we discovered that phosphorylated MCIP1 dissociates from calcineurin and binds with 14-3-3, thereby relieving its inhibitory effect on calcineurin activity. In summary, our findings reveal a previously unrecognized essential regulatory role of mitogen-activated protein kinase signaling in calcineurin activation through the reversible phosphorylation of a calcineurin-interacting protein, MCIP1. Show less