The Amino-Terminus of Nitric Oxide Sensitive Guanylyl Cyclase α1 Does Not Affect Dimerization but Influences Subcellular Localization

BACKGROUND: Nitric oxide sensitive guanylyl cyclase (NOsGC) is a heterodimeric enzyme formed by an α- and a β₁-subunit. A splice variant (C-α₁) of the α₁-subunit, lacking at least the first 236 amino acids has been described by Sharina et al. 2008 and has been shown to be expressed in differentiating human embryonic cells. Wagner et al. 2005 have shown that the amino acids 61-128 of the α₁-subunit are mandatory for quantitative heterodimerization implying that the C-α₁-splice variant should lose its capacity to dimerize quantitatively. METHODOLOGY/PRINCIPAL FINDINGS: In the current study we demonstrate preserved quantitative dimerization of the C-α₁-splice by co-purification with the β₁-subunit. In addition we used fluorescence resonance energy transfer (FRET) based on fluorescence lifetime imaging (FLIM) using fusion proteins of the β₁-subunit and the α₁-subunit or the C-α₁ variant with ECFP or EYFP. Analysis of the respective combinations in HEK-293 cells showed that the fluorescence lifetime was significantly shorter (≈0.3 ns) for α₁/β₁ and C-α₁/β₁ than the negative control. In addition we show that lack of the amino-terminus in the α₁ splice variant directs it to a more oxidized subcellular compartment. CONCLUSIONS/SIGNIFICANCE: We conclude that the amino-terminus of the α₁-subunit is dispensable for dimerization in-vivo and ex-vivo, but influences the subcellular trafficking

Experimental traumatic brain injury

Traumatic brain injury, a leading cause of death and disability, is a result of an outside force causing mechanical disruption of brain tissue and delayed pathogenic events which collectively exacerbate the injury. These pathogenic injury processes are poorly understood and accordingly no effective neuroprotective treatment is available so far. Experimental models are essential for further clarification of the highly complex pathology of traumatic brain injury towards the development of novel treatments. Among the rodent models of traumatic brain injury the most commonly used are the weight-drop, the fluid percussion, and the cortical contusion injury models. As the entire spectrum of events that might occur in traumatic brain injury cannot be covered by one single rodent model, the design and choice of a specific model represents a major challenge for neuroscientists. This review summarizes and evaluates the strengths and weaknesses of the currently available rodent models for traumatic brain injury

Cardiac adaptation to obesity and hypertension after heart transplantation

AbstractObesity and hypertension frequently develop after heart transplantation. The cardiac adaptation to obesity and hypertension was studied by determining hemodynamic and echocardiographic indexes in 10 obese hypertensive patients (body mass index ≥27.8 kg/m2in men or ≥ 27.3 kg/m2in women) matched by mean arterial pressure, age and gender with 10 nonobese hypertensive patients 1 year after cardiac transplantation. Cardiac output was 30% greater (p < 0.02) and systemic vascular resistance 25% lower (p < 0.01) in the obese than in the nonobese patients. Right ventricular systolic and pulmonary artery systolic, diastolic and mean pressures were also significantly higher (p < 0.05) in the obese patients. Left ventricular end-diastolic diameter was 25% greater (p < 0.05), left ventricular mass 28% greater (p < 0.02) and left ventricular end-diastolic volume 20% higher (p < 0.01) in the obese subjects. Left ventricular ejection fraction was significantly lower in the obese than in the nonobese subjects (34% vs. 51%, p < 0.05).These results indicate that the cardiac adaptation to obesity and hypertension after heart transplantation consists of left ventricular dilation and an increase in left ventricular mass associated with an increased cardiac output and lower peripheral vascular resistance. These adaptive changes that occur in obese hypertensive patients after heart transplantation might increase the long-term risk of graft failure, as suggested by their lower left ventricular ejection fraction 1 year after transplantation