Biology subjects

Alam, P.

Publications and source records attributed to Alam, P..

2 recordsLinked to original sources

bioRxiv2021

Polarized α-synuclein trafficking and transcytosis across Brain Endothelial Cells via Rab7-decorated carriers

Parkinsons disease is mainly caused by aggregation of -synuclein (-syn) in the brain. Exchange of -syn between the brain and peripheral tissues could have important pathophysiological and therapeutic implications, but the trafficking mechanism of -syn across the blood brain barrier (BBB) remains unclear. In this study, we therefore investigated uptake and transport mechanisms of -syn monomers and oligomers across an in vitro BBB model system. Both -syn monomers and oligomers were internalized by primary brain endothelial cells, with increased restriction of oligomeric over monomeric transport. To enlighten the trafficking route of monomeric -syn in brain endothelial cells, we investigated co-localization of -syn and intracellular markers of vesicular transport. Here, we observed the highest colocalization with clathrin, Rab7 and VPS35, suggesting a clathrin-dependent internalization, preferentially followed by a late endosome retromer-connected trafficking pathway. Furthermore, STED microscopy revealed monomeric -syn trafficking via Rab7-decorated carriers. Knockdown of Caveolin1, VPS35, and Rab7 using siRNA did not affect monomeric -syn uptake into endothelial cells. However, it significantly reduced transcytosis of monomeric -syn in the luminal-abluminal direction, suggesting a polarized regulation of monomeric -syn vesicular transport. Our findings suggest a direct role for Rab7 in polarized trafficking of monomeric -syn across BBB endothelium, and the potential of Rab7 directed trafficking to constitute a target pathway for new therapeutic strategies against Parkinsons disease and related synucleinopathies. Significance StatementIn the submitted manuscript, we describe the use of a state-of-the-art porcine blood-brain barrier model based on primary cells to get information about this important issue. We identify several hitherto undescribed cellular pathways to mediate polarized transport of alpha-synuclein. One of these paths we find regulated by Rab7 and can be inhibited by targeting several intracellular proteins such as VPS35, Caveolin1 and Rab7. New knowledge describing brain endothelial intracellular transport systems are highly warranted for identifying new target to alleviate Parkinsons disease. We believe that our findings could be the seed to establish new therapeutic strategies against Parkinsons disease and related synucleinopathies.

cell biology↗

bioRxiv2021

Adipocyte deletion of the RNA binding protein HuR induces cardiac hypertrophy and fibrosis

Adipose tissue continues to gain appreciation for its broad role as an endocrine organ, and disruptions in adipose tissue homeostasis plays a central role in cardiovascular physiology. We have previously shown that expression of the RNA binding protein HuR in adipose tissue mediates energy expenditure, but the potential cardiovascular impacts of this finding have not been explored. We show here that adipose tissue-specific deletion of HuR (Adipo-HuR-/-) is sufficient to induce the spontaneous development of cardiac hypertrophy and fibrosis. Hearts from Adipo-HuR-/- mice have increased left ventricular (LV) ejection fraction, rate of pressure generation, and LV posterior wall thickness that is accompanied by an increase in LV/body weight ratio and hypertrophic gene expression. Furthermore, Adipo-HuR-/- hearts display increased fibrosis by picrosirius red staining and periostin expression. To identify underlying mechanisms, we applied both RNA-seq and weighted gene co-expression network analysis (WGCNA) to define HuR-dependent changes in gene expression as well as significant relationships between adipose tissue gene expression and LV mass. RNA-seq results demonstrate a significant increase in pro-inflammatory gene expression in the subcutaneous white adipose tissue (scWAT) from Adipo-HuR-/- mice that is accompanied by an increase in serum levels of both TNF- and IL-6. WGCNA identified a significant enrichment in inflammation, apoptosis/cell death, and vesicle-mediated transport genes among those whose expression most significantly associated with CVD in Adipo-HuR-/-. In conclusion, we demonstrate that the loss of HuR expression in adipose tissue promotes the development of cardiac hypertrophy and fibrosis, potentially through modulation of inflammation and vesicle-mediated transport in scWAT. NEW AND NOTEWORTHYThis work demonstrates the spontaneous development of cardiac hypertrophy and fibrosis upon adipose tissue-specific deletion of the RNA binding protein HuR that appears to be mechanistically driven by HuR-dependent changes in inflammatory and extracellular vesicle transport mediating genes in the subcutaneous white adipose tissue. These results suggest that loss of HuR expression in adipose tissue in obesity, as demonstrated in mouse and humans by our group and others, may contribute to obesity-mediated CVD.

physiology↗